Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The effect of stratification of microplankton communities in the northern Strait of Georgia Haigh, Rowan 1988

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1988_A6_7 H34.pdf [ 15.19MB ]
Metadata
JSON: 831-1.0053243.json
JSON-LD: 831-1.0053243-ld.json
RDF/XML (Pretty): 831-1.0053243-rdf.xml
RDF/JSON: 831-1.0053243-rdf.json
Turtle: 831-1.0053243-turtle.txt
N-Triples: 831-1.0053243-rdf-ntriples.txt
Original Record: 831-1.0053243-source.json
Full Text
831-1.0053243-fulltext.txt
Citation
831-1.0053243.ris

Full Text

THE EFFECT OF STRATIFICATION ON MICROPLANKTON COMMUNITIES IN THE NORTHERN STRAIT OF GEORGIA by ROWAN HAIGH B.Sc. U n i v e r s i t y of B r i t i s h Columbia 1980 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department of Oceanography) We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA February 1988 © Rowan Haigh, 1988 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 DE-6(3/81) i i ABSTRACT The northern S t r a i t of Georgia (NSG) and adjacent Malaspina Complex of i n l e t s (MC) were s t u d i e d to determine the e f f e c t of s t r a t i f i c a t i o n on microplankton communities. The NSG was dominated by n a n o f l a g e l l a t e s i n s p r i n g . There was no evidence of a v e r n a l diatom bloom in the S t r a i t , perhaps due to wind turbu l e n c e or microzooplankton g r a z i n g . In e a r l y summer regimes were conducive to diatom growth but the northern S t r a i t was e x p e r i e n c i n g a "mild" red t i d e . By l a t e summer, diatoms bloomed and p r e v a i l e d , presumably, t i l l the f a l l d e c l i n e . S t r a t i f i c a t i o n was g r e a t e s t i n l a t e summer, due c h i e f l y to temperature, with reduced surface s a l i n i t i e s on the east s i d e from F r a s e r River r u n o f f . At t h i s time b i o l o g i c a l p a r t i t i o n i n g was pronounced, r e s u l t i n g i n a mosaic of organismal groups. Although s t r a t i f i c a t i o n had d e c l i n e d by e a r l y autumn, the mosaicism was maintained and strengthened. Diatoms were most abundant i n the north and on the west s i d e where s t r a t i f i c a t i o n was l e a s t , i n areas of t i d a l t u r b u l e n c e . P h o t o s y n t h e t i c n a n o f l a g e l l a t e s and p h o t o s y n t h e t i c d i n o f l a g e l l a t e s favoured the more s t r a t i f i e d east s i d e . C i l i a t e d i s t r i b u t i o n s m i r r o r e d those of the n a n o f l a g e l l a t e s . The MC was thought to be a more s t r a t i f i e d v e r s i o n of the NSG but i t was found to be a f a i r l y mixed water body due to t i d a l a c t i o n . I t was s h e l t e r e d from winds which allowed the e a r l y blooming of diatoms. These were maintained f o r s e v e r a l months by a t i d a l j e t through Malaspina I n l e t t h at probably i n j e c t e d n u t r i e n t s i n t o the j u n c t i o n of Malaspina, Okeover, and L a n c e l o t I n l e t s . P r i n c i p a l components a n a l y s i s was used to reduce the d i m e n s i o n a l i t y of the b i o l o g i c a l d a t a s e t , and c a n o n i c a l c o r r e l a t i o n a n a l y s i s allowed the c o u p l i n g of environmental data to the b i o l o g i c a l p r i n c i p a l components. I t was found that PCI r e f l e c t e d g e n e r a l biomass while PC's II and I I I were most o f t e n r e l a t e d t o depth and l o c a t i o n . These l a t t e r two were u t i l i s e d to r e s o l v e the s p e c i e s i n f o r m a t i o n i n three-dimensions. In g e n e r a l , n a n o f l a g e l l a t e s populated s u r f a c e waters whereas diatoms tended to occupy deeper depths. M u l t i p l e r e g r e s s i o n a n a l y s i s was performed on organismal groups to e x p l o r e how biomass was a f f e c t e d by s t r a t i f i c a t i o n , p y c n o c l i n e depth, s u r f a c e temperature ( s e a s o n a l i t y ) , n i t r a t e , and g r a z i n g . i v TABLE OF CONTENTS ABSTRACT i i LIST OF TABLES v i LIST OF FIGURES ix ACKNOWLEDGEMENTS x i i i 1 . INTRODUCTION 1 2. METHODS 17 2.1 Study S i t e s 17 2.1.1 Northern S t r a i t of Georgia 17 2.1.2 Malaspina Complex 22 2.2 Pump Sampling System 22 2.3 N i t r a t e 23 2.4 C h l o r o p h y l l 24 2.5 Phytoplankton 27 2.6 Volume to Carbon Conversion 29 3. RESULTS 36 3.1 Depth-Location A n a l y s i s v i a Ca n o n i c a l C o r r e l a t i o n .. 36 3.1.1 M u l t i v a r i a t e S t a t i s t i c s 36 3.1.2 March, 1986 40 3.1.2.1 N . S t r a i t of Georgia vs Malaspina Complex . 40 3.1.2.2 Northern S t r a i t of Georgia 49 3.1.3 A p r i l , 1986 56 3.1.3.1 N . S t r a i t of Georgia vs Malaspina Complex . 56 3.1.3.2 Northern S t r a i t of Georgia 64 3.1.4 June, 1 986 71 3.1.4.1 N . S t r a i t of Georgia vs Malaspina Complex . 71 3.1.4.2 Northern S t r a i t of Georgia 79 3.1 .5 August, 1 986 85 3.1.5.1 N . S t r a i t of Georgia vs Malaspina Complex . 85 3.1.5.2 Northern S t r a i t of Georgia 93 3.1.6 September, 1986 99 3.1.6.1 N . S t r a i t of Georgia vs Malaspina Complex . 99 3.1.6.2 Northern S t r a i t of Georgia 107 3.1.7 C h l o r o p h y l l Maxima Biomass Dominants 113 3.1.8 CCA Summary 117 3.2 ORGANISMAL TRENDS WITH STRATIFICATION 119 3.2.1 March 119 3.2.2 A p r i l 1 32 3.2.3 June 144 3.2.4 August 1 56 3.2.5 September 169 3.3 MULTIPLE REGRESSION ANALYSIS 181 3.3.1 S t a t i s t i c a l Background 181 3.3.2 Regression Analyses 185 4. DISCUSSION 217 4.1 Absence of a S p r i n g Bloom 217 4.2 Advanced E c o l o g i c a l S t a b i l i t y 222 4.3 B i o l o g i c a l Mosaicism 225 4.4 Phytoplankton Succession 231 4.5 Comparison with Other Areas 234 5. CONCLUSIONS 241 6. SUGGESTIONS FOR FURTHER RESEARCH 245 v i REFERENCES 247 APPENDIX 1. SPECIES OF THE NSG AND MC 263 APPENDIX 2. SPECIES OF SPECIAL INTEREST 268 Alexandrium o s t e n f e l d i i 268 Chaetoceros convolutus 268 Dict y o c h a speculum 269 Dinophysis acuminata 269 Din o p h y s i s f o r t i i 270 Dinophysis norvegica 270 Dinophysis ovum 270 Dinophysis spp 271 Gymnodinium sanguineum 271 Heterosigma akashiwo 271 N o c t i l u c a s c i n t i l l a n s 272 Protogonyaulax c a t e n e l l a 272 Prorocentrum g r a c i l e 272 Protogonyaulax tamarensis 273 APPENDIX 3. Unknown f l a g e l l a t e s 287 v i i LIST OF TABLES Table 1 . Species codes 30 Table 2. Species c o r r e l a t i o n s with p r i n c i p a l components, NSG+MC, March, 1986 . 45 Table 3. C o r r e l a t i o n s with c a n o n i c a l v a r i a t e s , NSG+MC, March, 1986 47 Table 4. Species c o r r e l a t i o n s with p r i n c i p a l components, NSG, March, 1986 53 Table 5. C o r r e l a t i o n s with c a n o n i c a l v a r i a t e s , NSG, March, 1986 54 Table 6. Species c o r r e l a t i o n s with p r i n c i p a l components, NSG+MC, A p r i l , 1986 . . 60 Table 7. C o r r e l a t i o n s with c a n o n i c a l v a r i a t e s , NSG+MC, A p r i l , 1986 62 Table 8. Species c o r r e l a t i o n s with p r i n c i p a l components, NSG, A p r i l , 1986 68 Table 9. C o r r e l a t i o n s with c a n o n i c a l v a r i a t e s , NSG, A p r i l , 1986 69 Table 10. Species c o r r e l a t i o n s with p r i n c i p a l components, NSG+MC, June, 1986 75 Table 11. C o r r e l a t i o n s with c a n o n i c a l v a r i a t e s , NSG+MC, June, 1986 77 Table 12. Species c o r r e l a t i o n s with p r i n c i p a l components, NSG, June, 1986 82 Table 13. C o r r e l a t i o n s with c a n o n i c a l v a r i a t e s , NSG, June, v i i i 1986 83 Table 14. Species c o r r e l a t i o n s with p r i n c i p a l components, NSG+MC, August, 1986 89 Table 15. C o r r e l a t i o n s with c a n o n i c a l v a r i a t e s , NSG+MC, August, 1986 91 Table 16. Species c o r r e l a t i o n s with p r i n c i p a l components, NSG, August, 1986 96 Table 17. C o r r e l a t i o n s with c a n o n i c a l v a r i a t e s , NSG, August, 1986 97 Table 18. Species c o r r e l a t i o n s with p r i n c i p a l components, NSG+MC, September, 1986 103 Table 19. C o r r e l a t i o n s with c a n o n i c a l v a r i a t e s , NSG+MC, September, 1986 1 05 Table 20. Species c o r r e l a t i o n s with p r i n c i p a l components, NSG, September, 1 986 110 Table 21. C o r r e l a t i o n s with c a n o n i c a l v a r i a t e s , NSG, September, 1986 111 Table 22. C h l o r o p h y l l maxima biomass dominants 116 Table 23. Species observed i n the NSG & MC 264 ix LIST OF FIGURES Fi g u r e 1. Study area with s t a t i o n p o s i t i o n s 18 F i g u r e 2. P r e d i c t e d t i d a l c u r r e n t d i r e c t i o n at sample times 21 F i g u r e 3. Species c o r r e l a t i o n s with PCs II & I I I , NSG vs MC, March, 1986 48 F i g u r e 4. Species c o r r e l a t i o n s with PCs II & I I I , NSG, March, 1986 55 F i g u r e 5. Species c o r r e l a t i o n s with PCs II & I I I , NSG vs MC, A p r i l , 1 986 63 F i g u r e 6. Species c o r r e l a t i o n s with PCs II & I I I , NSG, A p r i l , 1986 70 F i g u r e 7. Species c o r r e l a t i o n s with PCs II & I I I , NSG vs MC, June, 1986 78 F i g u r e 8. Species c o r r e l a t i o n s with PCs II & I I I , NSG, June, 1986 84 F i g u r e 9. Species c o r r e l a t i o n s with PCs II & I I I , NSG vs MC, August, 1986 92 F i g u r e 10. Species c o r r e l a t i o n s with PCs II & I I I , NSG, August, 1986 98 F i g u r e 11. Species c o r r e l a t i o n s with PCs II & I I I , NSG vs MC, September, 1986 106 F i g u r e 12. Species c o r r e l a t i o n s with PCs II & I I I , NSG, September, 1986 112 F i g u r e 13. S t r a t i f i c a t i o n c ontours, NSG, March, 1 986 123 X F i g u r e 14. Organismal biomass contours, NSG, March, 1986 ..123 F i g u r e 15. S t r a t i f i c a t i o n and biomass along t r a n s e c t s i n the NSG, March, 1986 128 F i g u r e 16. S t r a t i f i c a t i o n and biomass along t r a n s e c t s i n the MC, March, 1986 128 F i g u r e 17. S t r a t i f i c a t i o n contours, NSG, A p r i l , 1986 135 F i g u r e 1 8 . Organismal biomass contours, NSG, A p r i l , 1986 ..135 F i g u r e 19. S t r a t i f i c a t i o n and biomass along t r a n s e c t s i n the NSG, A p r i l , 1986 . . 140 F i g u r e 20. S t r a t i f i c a t i o n and biomass along t r a n s e c t s i n the MC, A p r i l , 1 986 1 40 F i g u r e 21. S t r a t i f i c a t i o n contours, NSG, June, 1986 147 F i g u r e 22. Organismal biomass contours, NSG, June, 1986 ...147 F i g u r e 23. S t r a t i f i c a t i o n and biomass along t r a n s e c t s i n the NSG, June, 1986 152 F i g u r e 24. S t r a t i f i c a t i o n and biomass along t r a n s e c t s i n the MC, June, 1986 152 F i g u r e 25. S t r a t i f i c a t i o n contours, NSG, August, 1986 160 F i g u r e 26. Organismal biomass contours, NSG, August, 1986 .160 F i g u r e 27. S t r a t i f i c a t i o n and biomass along t r a n s e c t s i n the NSG, August, 1986 165 F i g u r e 28. S t r a t i f i c a t i o n and biomass along t r a n s e c t s i n the MC, August, 1986 165 F i g u r e 29. S t r a t i f i c a t i o n contours, NSG, September, 1986 ..172 F i g u r e 30. Organismal biomass contours, NSG, September, 1986 172 F i g u r e 31. S t r a t i f i c a t i o n and biomass along t r a n s e c t s i n the NSG, September, 1986 177 F i g u r e 32. S t r a t i f i c a t i o n and biomass along t r a n s e c t s i n the MC, September, 1986 177 F i g u r e 33. Organismal r e g r e s s i o n c o e f f i c i e n t s 197 F i g u r e 34. Diatom r e g r e s s i o n a n a l y s i s ..197 F i g u r e 35. Diatom r e g r e s s i o n c o e f f i c i e n t s 197 F i g u r e 36. Lower biomass diatom r e g r e s s i o n a n a l y s i s 201 F i g u r e 37. Higher biomass diatom r e g r e s s i o n a n a l y s i s 201 F i g u r e 38. P h o t o s y n t h e t i c d i n o f l a g e l l a t e r e g r e s s i o n a n a l y s i s ..201 F i g u r e 39. H e t e r o t r o p h i c d i n o f l a g e l l a t e r e g r e s s i o n a n a l y s i s 205 F i g u r e 40. H e t e r o t r o p h i c d i n o f l a g e l l a t e r e g r e s s i o n c o e f f i c i e n t s 205 F i g u r e 41. Gyrodinium r e g r e s s i o n a n a l y s i s 205 F i g u r e 42. P r o t o p e r i d i n i u m r e g r e s s i o n a n a l y s i s 209 F i g u r e 43. P h o t o s y n t h e t i c n a n o f l a g e l l a t e r e g r e s s i o n a n a l y s i s 209 F i g u r e 44. H e t e r o t r o p h i c n a n o f l a g e l l a t e r e g r e s s i o n a n a l y s i s 209 F i g u r e 45. P h o t o s y n t h e t i c f l a g e l l a t e r e g r e s s i o n a n a l y s i s ..213 F i g u r e 46. Mesodinium rubrum r e g r e s s i o n a n a l y s i s 213 F i g u r e 47. H e t e r o t r o p h i c c i l i a t e r e g r e s s i o n a n a l y s i s 213 F i g u r e 48. D i s t r i b u t i o n of Alexandrium o s t e n f e l d i i i n the NSG 274 F i g u r e 49. D i s t r i b u t i o n of Chaetoceros convolutus i n the NSG 275 F i g u r e 50. D i s t r i b u t i o n of D i c t y o c h a speculum i n the NSG ..276 F i g u r e 51. D i s t r i b u t i o n of D i n o p h y s i s acuminata i n the NSG 277 F i g u r e 52. D i s t r i b u t i o n of Dinophysis f o r t i i i n the NSG ...277 F i g u r e 53. D i s t r i b u t i o n of Dinophysis norveqica i n the NSG 278 F i g u r e 54. D i s t r i b u t i o n of Dinophysis ovum i n the NSG 279 F i g u r e 55. D i s t r i b u t i o n of Dinophysis spp. In the NSG 280 F i g u r e 56. D i s t r i b u t i o n of Gymnodinium sanquineum i n the NSG 281 F i g u r e 57. D i s t r i b u t i o n of Heterosigma akashiwo i n the NSG 282 F i g u r e 58. D i s t r i b u t i o n of N o c t i l u c a s c i n t i l l a n s i n the NSG 283 F i g u r e 59. D i s t r i b u t i o n of Protoqonyaulax c a t e n e l l a i n the NSG 284 F i g u r e 60. D i s t r i b u t i o n of Prorocentrum g r a c i l e i n the NSG 285 F i g u r e 61. D i s t r i b u t i o n of Protoqonyaulax tamarensis i n the NSG 286 ACKNOWLEDGEMENTS I wish to express deep g r a t i t u d e towards my s u p e r v i s o r , Dr. F.J.R. "Max" T a y l o r . H i s support and good humour helped make the study a p l e a s a n t e x p e r i e n c e . His w i l l i n g n e s s to l e t me e x p l o r e at my own pace allowed me t o l e a r n many i n v a l u a b l e t h i n g s . I would a l s o l i k e to thank my committee members, Dr. P.J. H a r r i s o n and Dr. T.R. Parsons, who were always w i l l i n g to o f f e r a d v i c e . There were many others i n the Oceanography Department who l e n t a hand or dispensed t h e i r wisdom f r e e l y , e s p e c i a l l y the boys i n Dr. H a r r i s o n ' s l a b as w e l l as the summer h e l p e r s Sharon MacKinnon, M i c h e l Junger, and James Custance H e r r i n g t o n . Thank you a l l . The l a b would have been f a r l e s s e njoyable had i t not been f o r the humour of the NEPCC c u r a t o r s . F i r s t there was the ever-amused Ms. Judy Acreman who k i n d l y imparted a l l her diatom knowledge (save those dreaded i c e diatoms). Next came the e b u l l i e n t E l a i n e Simons (Elbabe) with u p l i f t i n g t a i l s of K i s s y . T h a n k f u l l y both were t o l e r a n t of my blackboard f a n t a s i e s . I s a l u t e my t h e s i s comrades Peter C l i f f o r d , S h i r l e y French, and Pat O'Brien without whom the r e would have been no sympathetic persons to share t h e s i s - w r i t i n g woes. I am most g r a t e f u l t o the s t a f f a t the B i o s c i e n c e s Data Centre, A l i s t a i r B l a c h f o r d , S h i r l e y Ludwig, and C h a r l e s Mathieson. They made computing easy and were always h e l p f u l when c o n d i t i o n s were l e a d i n g t o i n s a n i t y . F i n a l l y , I wish to thank Darren (Demon Chaos Uhuru I r ) and Mousie f o r t h e i r emotional support and deep i n s i g h t . 1 1. INTRODUCTION In theory, phytoplankton s u c c e s s i o n i n temperate areas i s an o r d e r l y , almost p r e d i c t a b l e c y c l e , e x e m p l i f i e d by R i l e y (1942), Takahashi et a l . (1977), and H a l l e g r a e f f and Reid (1986). Takahashi et a l . (1977) found t h a t i n Saanich I n l e t there i s a main bloom of diatoms i n s p r i n g which d e p l e t e the upper waters of n i t r a t e , f o l l o w e d by p e r i o d i c summer blooms, l a s t i n g a few days or weeks. These sm a l l e r blooms are a r e s u l t of o c c a s i o n a l turbulence which i n t r o d u c e s n i t r a t e i n t o a n u t r i e n t - l i m i t e d euphotic zone. Then, i n autumn there i s u s u a l l y a second diatom bloom r e s u l t i n g from f a l l storms pumping n u t r i e n t s back i n t o the upper l a y e r s where l i g h t i s s t i l l s u f f i c i e n t f o r growth. Winter i s dominated by n a n o f l a g e l l a t e s which, presumably, are the only organisms a b l e to t o l e r a t e such low l i g h t l e v e l s (Watanabe, 1978). Margalef (1958) recognised four s u e c e s s i o n a l stages: Stage I i s c h a r a c t e r i s e d by s m a l l - c e l l e d diatoms with l a r g e s u r f a c e area to volume r a t i o s and high d i v i s i o n r a t e s (1-2 d i v - d a y - 1 ) . T h i s maximising of s u r f a c e area i s a good a d a p t a t i o n to i n c r e a s e the a v a i l a b l e pigment's e f f i c i e n c y , i n e f f e c t maximising p h o t o s y n t h e s i s per u n i t volume by de c r e a s i n g s e l f - s h a d i n g of c h l o r o p l a s t s (Taguchi,1976). C h a r a c t e r i s t i c of Stage I are Skeletonema costatum, L e p t o c y l i n d r u s minimus, and T h a l a s s i o s i r a n o r d e n s k i o e l d i i . Stage II i s a mixed community of l a r g e r diatoms with l a r g e s u r f a c e area to volume r a t i o s and lower growth r a t e s . C h a r a c t e r i s t i c s p e c i e s are T h a l a s s i o s i r a  r o t u l a , Detonula pumila, Chaetoceros spp., and R h i z o s o l e n i a spp. Stage III occurs when the water column has remained s t r a t i f i e d and n u t r i e n t s have been exhausted i n the upper euphotic. Stage II diatoms sink out of t h i s zone as an adaptive s t r a t e g y ( S t e e l e & Yentsch, 1960) and 2 d i n o f l a g e l l a t e s are favoured because of t h e i r m o t i l i t y which allows them to s e l e c t the environment that best s u i t s them. Often they w i l l swim up to the s u r f a c e d u r i n g the day f o r p h o t o s y n t h e s i s ( p o s i t i v e p h o t o t a x i s ) and down to the n u t r i c l i n e at night f o r n i t r a t e uptake ( p o s i t i v e g e o t a x i s ) . Eppley et a l , (1968) found t h i s g e n e r a l response i s true f o r Gonyaulax p o l y e d r a as d i d Hasle (1950) f o r Gonyaulax  polyedra and Prorocentrum micans; however, the l a t t e r a l s o found a reverse m i g r a t i o n p a t t e r n f o r Ceratium  t r i p o s . Stage IV, termed "red t i d e " , occurs i f the water has remained calm f o r a number of weeks. As Margalef's s u c c e s s i o n a l sequence proceeds, the d i v e r s i t y w i l l i n c r e a s e to a c e r t a i n p o i n t , then decrease (Margalef, 1958). T h i s h e t e r o g e n e i t y i s t i e d to t u r b u l e n c e which a l s o decreases along the s u c c e s s i o n a l pathway. Heterogeneity can occur not only i n the h o r i z o n t a l d i r e c t i o n but a l s o i n the v e r t i c a l , which i s b a s i c a l l y what happens when the seasonal thermocline develops. Besides the change i n s p e c i e s d i v e r s i t y there are changes i n d i v e r s i t y of pigments (Margalef, 1963). As s u c c e s s i o n u n f o l d s , the p r o p o r t i o n of c h i a to t o t a l pigment complexes supposedly decreases, r e f l e c t i n g the s h i f t from diatom dominance to f l a g e l l a t e dominance. F l a g e l l a t e s are composed of groups such as e u g l e n o i d s , n a n o f l a g e l l a t e s , d i n o f l a g e l l a t e s , e t c . which c o l l e c t i v e l y c o n t a i n a wide a r r a y of c h l o r o p h y l l s (b&c) and a c c e s s o r y pigments ( f u c o x a n t h i n , p e r i d i n i n , e t c . ) . Another i n t e r e s t i n g f e a t u r e p o i n t e d out by Margalef (1963) i s that e a r l y s u c c e s s i o n a l s p e c i e s are much e a s i e r to c u l t u r e than l a t e r stage s p e c i e s . T h i s former group seems to have the a b i l i t y to produce i t s own growth f a c t o r s (e.g., v i t a m i n s ) whereas the l a t t e r group i s dependent on e x t e r n a l sources. To 3 make up f o r t h i s d e f i c i e n c y , l a t e r s u c c e s s i o n a l s p e c i e s are more able to produce t o x i c compounds which may confer an adaptive advantage v i a b i o c h e m i c a l e x c l u s i o n . P r o v a s o l i (1979) d i s c u s s e d s t u d i e s which found a l g a l e x c r e t i o n of Vitamin B12 b i n d e r s and suggested that these binders l i m i t s p e c i e s r e q u i r i n g t h i s growth f a c t o r . Margalef (1978) suggested that the most important f a c t o r s c o n t r o l l i n g phytoplankton dynamics and s u c c e s s i o n are n u t r i e n t f l u x and t u r b u l e n c e . Margalef et a_l. ( 1 979) i n t r o d u c e d a phytoplankton "mandala" which i s based on n u t r i e n t c o n c e n t r a t i o n , t u r b u l e n c e , and s t r a t i f i c a t i o n . These parameters are probably the three b a s i c d r i v i n g f o r c e s of s u c c e s s i o n along with l i g h t i r r a d i a n c e s . U l t i m a t e l y i n temperate zones, these f a c t o r s are determined by s e a s o n a l i t y . Sverdrup's (1953) model of c r i t i c a l depth d e s c r i b e s p h o t o s y n t h e t i c p r o d u c t i o n and r e s p i r a t o r y breakdown of organic matter with depth. P h o t o s y n t h e t i c p r o d u c t i o n decreases l o g a r i t h m i c a l l y with depth while r e s p i r a t i o n i s independent of depth. R e s p i r a t i o n w i l l be somewhat e l e v a t e d near the s u r f a c e when temperatures are higher ( G i l m a r t i n , 1964). The compensation depth has been d e f i n e d as the depth at which p h o t o s y n t h e s i s equals r e s p i r a t i o n while c r i t i c a l depth d e s c r i b e s the depth at which t o t a l p r o d u c t i o n of o r g a n i c matter equals the t o t a l breakdown over the water column. The r a t i o of c r i t i c a l depth to compensation depth i n c r e a s e s as the season advances. The model i s q u i t e t h e o r e t i c a l and s u b j e c t to numerous assumptions which are probably e a s i l y v i o l a t e d i n nature. However, i t s 4 c o n t r i b u t i o n to our understanding of why blooms should occur i s without q u e s t i o n . A bloom w i l l occur only when the depth of mixing i s l e s s than the c r i t i c a l depth, otherwise r e s p i r a t o r y use of organic matter w i l l exceed the p h o t o s y n t h e t i c p r o d u c t i o n . In winter the depth of mixing w i l l be g r e a t e r not only because there i s seasonal t u r b u l e n c e due to wind but a l s o because the ambient l i g h t i r r a d i a n c e i s l e s s . Consequently, both the compensation and c r i t i c a l depths w i l l be nearer the s u r f a c e . Under winter c o n d i t i o n s one would expect a complete absence of p r o d u c t i o n , r e s u l t i n g i n Margalef's infamous " v o i d " (Margalef et a l . , 1979). In f a c t , winter has a f a i r l y s u b s t a n t i a l p o p u l a t i o n of n a n o f l a g e l l a t e s because some of Sverdrup's assumptions may not be t r u e . F i r s t l y , t urbulence may not be s u f f i c i e n t to mix phytoplankton evenly throughout the mixed l a y e r , r e s u l t i n g i n a g r e a t e r p r o p o r t i o n of c e l l s above the compensation depth (Sverdrup, 1953) and a g r e a t e r than p r e d i c t e d p r o d u c t i o n . Secondly, even i f turbulence i s strong, s p e c i e s showing p o s i t i v e p h o t o t a x i s w i l l be c o n c e n t r a t e d more i n s u r f a c e waters and again p r o d u c t i o n w i l l be underestimated. Ryther (1956) assumed that the r a t i o of p h o t o s y n t h e s i s to r e s p i r a t i o n at l i g h t s a t u r a t i o n i s approximately 10 so that winter p o p u l a t i o n s would be producing j u s t enough to maintain themselves. As the seasons advance from winter to s p r i n g , ambient l i g h t i n c r e a s e s which deepens the compensation depth, while wind turbu l e n c e may a l s o decrease somewhat, reducing the depth of mixing. A l s o , i n c r e a s e d i n s o l a t i o n r e s u l t s i n s u r f a c e warming 5 and the beginnings of thermal s t r a t i f i c a t i o n . In March and A p r i l , s u r f a c e temperatures i n the S t r a i t of Georgia i n c r e a s e d u r i n g the day, but the heat i s d i s s i p a t e d d u r i n g the night ( T u l l y and Dodimead, 1957). Presumably, the p y c n o c l i n e begins near the s u r f a c e and as i t gains s t r e n g t h , i.e., as the d e n s i t y g r a d i e n t becomes steeper, i t i s a l s o pushed deeper by winds. At some degree of s t r a t i f i c a t i o n , the d e n s i t y g r a d i e n t w i l l be s u f f i c i e n t to e f f e c t i v e l y act as a b a r r i e r to v e r t i c a l mixing from above. The e f f e c t of s t r a t i f i c a t i o n i s to i n c r e a s e the average i r r a d i a n c e of t h i s upper mixed zone and consequently deepen the compensation depth. There have been some d i f f e r e n c e s of o p i n i o n as to whether the s p r i n g bloom r e s u l t s s o l e l y from i n c r e a s e d seasonal i r r a d i a n c e or from the g r e a t e r average l i g h t i r r a d i a n c e due to s t r a t i f i c a t i o n . Sverdrup (1953) t e s t e d h i s model on o b s e r v a t i o n s from Weathership "M" i n the Norwegian Sea. In the s p r i n g of 1949, he found that the i n i t i a l phytoplankton i n c r e a s e was due to a seasonal i n c r e a s e i n compensation depth and not s t r a t i f i c a t i o n . Parsons and LeBrasseur (1968) a p p l i e d Sverdrup's model to data obtained from Ocean Weather S t a t i o n "P" i n the NE P a c i f i c . They found that the i n i t i a l p r o d u c t i o n i n c r e a s e i n March was due to i n c r e a s e d i r r a d i a n c e whereas i n A p r i l the pro d u c t i o n responded to both higher l i g h t l e v e l s and s t r a t i f i c a t i o n . By May any p r o d u c t i o n i n c r e a s e was due p r i m a r i l y to s t r a t i f i c a t i o n . O v e r a l l , they concluded that higher i r r a d i a n c e was twice as important to phytoplankton growth r a t e s as i n c r e a s e d s t r a t i f i c a t i o n . Sakshaug and Myklestad (1973), 6 studying Trondheimsfjord i n Norway, found that s p r i n g diatom growth began i n c r e a s i n g at i r r a d i a n c e s of 120-140 l y d a y " 1 . They f e l t that the i n c r e a s e was due mainly to t h i s i n c r e a s e d l i g h t r a t h e r than the degree of tu r b u l e n c e (which does not r e a l l y i n d i c a t e the e f f e c t of s t r a t i f i c a t i o n ) . However, diatom growth in t h i s f j o r d i n c r e a s e d even when the upper mixed l a y e r reached 30-50 m. The only o c c a s i o n when the s p r i n g bloom developed p o o r l y was i n 1966 when the mixed l a y e r extended down to 100-150 m. Conversely, G i l m a r t i n (1964), who s t u d i e d p r o d u c t i v i t y i n Indian Arm near Vancouver, found that a p r o d u c t i o n i n c r e a s e i n March was not a s s o c i a t e d with any marked r a d i a n t i n c r e a s e and i m p l i c a t e d s t r a t i f i c a t i o n as the main f a c t o r r e s p o n s i b l e . Pingree et a l . (1976) found that i n the C e l t i c Sea thermal s t r a t i f i c a t i o n developed e a r l i e s t i n areas with lower t i d a l stream amplitudes, and i t was at these s i t e s t h a t phytoplankton f i r s t i n c r e a s e d . Semina (1960) observed biomass i n c r e a s i n g with s t r a t i f i c a t i o n due to s p r i n g r u n o f f and m e l t i n g i c e i n the western B e r i n g Sea and o f f the Kamchatka c o a s t . M a r s h a l l (1958) noted that p r o d u c t i o n i n c r e a s e d i n A r c t i c waters (March-April) before i t d i d i n the A t l a n t i c (May-June). In the former r e g i o n the c r i t i c a l depth exceeded the depth of mixing e a r l i e r because melt water produced p y c n o c l i n e s at 10-25 m, e f f e c t i v e l y d e c r e a s i n g the depth of mixing. S t r a t i f i c a t i o n may have no e f f e c t i n shallow seas i f the c r i t i c a l depth i s g r e a t e r than the bottom depth (e.g., western Hecate S t r a i t , Perry et a l . , 1983). I t t h e r e f o r e seems that s t r a t i f i c a t i o n ' s e f f e c t on the i n i t i a l 7 s p r i n g p r o d u c t i v i t y i n c r e a s e i s s i t e dependent. In the Norwegian Sea and perhaps the Norwegian f j o r d s , wind t u r b u l e n c e i s h i g h whereas the C e l t i c Sea, i f not l e s s t u r b u l e n t , i s s u b j e c t to g r e a t e r i n s o l a t i o n , being f u r t h e r south. Indian Arm i s d e f i n i t e l y l e s s exposed than these r e g i o n s , being s i t u a t e d w i t h i n B.C.'s mainland coast and a d d i t i o n a l p r o t e c t i o n i s a f f o r d e d by Vancouver I s l a n d . Cushing (1962) modifed Sverdrup's model and came up with a way of e s t i m a t i n g the c r i t i c a l depth which p r e d i c t s f i e l d o b s e r v a t i o n s b e t t e r . B a s i c a l l y , he allowed f o r the i n h i b i t i o n of p h o t o s y n t h e s i s at high l i g h t i r r a d i a n c e s , and r a t h e r than using a c o e f f i c i e n t of l i g h t e x t i n c t i o n , he i n t r o d u c e d the e x t i n c t i o n of energy. Cushing's model determines how the p o t e n t i a l p r o d u c t i v e r a t e i s a f f e c t e d by v e r t i c a l mixing. Sverdrup's o r i g i n a l model p r e d i c t e d no p r o d u c t i o n i n winter because the depth of mixing exceeded the c r i t i c a l depth, when i n f a c t , examples of s u b s t a n t i a l winter p r o d u c t i o n were known. Using energy e x t i n c t i o n c o e f f i c i e n t s , Cushing c a l c u l a t e d monthly p o t e n t i a l p r o d u c t i v e r a t e s , Rp, which are r a t e s that algae would t h e o r e t i c a l l y achieve i f they remained i n the p h o t i c zone. Next, compensation depths, Dc, were c a l c u l a t e d from estimates of t o t a l a v a i l a b l e energy f o r p h o t o s y n t h e s i s reduced by the a p p r o p r i a t e energy e x t i n c t i o n c o e f f i c i e n t s . T h e o r e t i c a l l y , Dc should be the depth at which Rp i s zero. The l a s t v a r i a b l e needed i s the depth of mixing, Dm, determined as the depth of f r i c t i o n a l r e s i s t a n c e ( d e r i v e d from average wind s t r e n g t h measurements). P r o d u c t i v e r a t e s are then c a l c u l a t e d 8 thus: R = Rp x (Dc/Dm) (1) Dc/Dm i s an i n d i c a t i o n of mixing. The model p r e d i c t s that there i s enough p o t e n t i a l p r o d u c t i v e energy i n winter to give r i s e to s u b s t a n t i a l p r o d u c t i o n i f wind t u r b u l e n c e remains low. Thus, whether s t r a t i f i c a t i o n or seasonal l i g h t t r i g g e r s blooms, depends on how much wind the area r e c e i v e s . In G i l m a r t i n ' s (1964) study, l i g h t energy remained constant and so d i d Dc and Rp while the depth of mixing decreased due to perhaps a s l a c k e n i n g i n winter winds. At Sverdrup's (1953) Weathership "M" winds were of gr e a t e r magnitude and more co n s t a n t . The depth of mixing stayed constant while seasonal l i g h t i n c r e a s e d , r e s u l t i n g i n Dc and Rp i n c r e a s i n g . In l e s s extreme s i t u a t i o n s there w i l l be both a seasonal l i g h t i n c r e a s e as w e l l as a decrease i n seasonal t u r b u l e n c e . S t r a t i f i c a t i o n can be determined by an input of heat from the atmosphere or s a l i n i t y from t e r r i g e n o u s r u n o f f . The e f f e c t s t r a t i f i c a t i o n w i l l have on p r o d u c t i o n depends on how e f f e c t i v e the d e n s i t y b a r r i e r i s a g a i n s t v e r t i c a l mixing by wind. I f winds remain s t r o n g a l l s p r i n g , s t r a t i f i c a t i o n w i l l not be able to b u i l d up s u f f i c i e n t p o t e n t i a l energy to decrease the depth of mixing and pro d u c t i o n w i l l depend mostly on the seasonal l i g h t i n c r e a s e . The lower the winds are, the e a r l i e r s t r a t i f i c a t i o n can have an e f f e c t . When the l i g h t regime has become more f a v o u r a b l e , n a n o f l a g e l l a t e s i n c r e a s e d r a m a t i c a l l y , but are e v e n t u a l l y 9 surpassed by diatoms (Watanabe, 1978) which have higher growth r a t e s at these i r r a d i a n c e s (Eppley et a l . , 1969). N u t r i e n t s are in good supply due to winter mixing so that the diatoms bloom and e v e n t u a l l y use up the s u r f a c e n u t r i e n t s . The s p r i n g bloom of diatoms i s more or l e s s common to a l l temperate water bodies due to the mechanisms a s s o c i a t e d with s e a s o n a l i t y at these l a t i t u d e s . Once the bloom has ended, phytoplankton dynamics of l a t e s p r i n g and e a r l y summer depend very much on l o c a t i o n . In the case of Trondheimsfjord i n Norway (Sakshaug and Myklestad, 1973), a second s p r i n g bloom occ u r r e d a s s o c i a t e d with b r a c k i s h runoff d u r i n g May and June. There was a l s o a net seasonal t r a n s p o r t of phytoplankton p o p u l a t i o n s seaward and continuous p o p u l a t i o n replenishment. T h i s second bloom was found to be f a r more u n p r e d i c t a b l e than the f i r s t as r i v e r d i s c h a r g e p a t t e r n s were q u i t e v a r i a b l e from year to year. G i l m a r t i n ' s (1964) study of Indian Arm only found one s p r i n g bloom i n May, which began when the s p r i n g runoff slackened. Production was probably s t i l l o c c u r r i n g d u r i n g the d i s c h a r g e but the net t r a n s p o r t out of the i n l e t was g r e a t e r than the i n c r e a s e i n phytoplankton biomass. For i n s t a n c e , d u r i n g the 1959 s p r i n g d i s c h a r g e , t r a n s p o r t sometimes exceeded 400 m 3*s" 1 which meant a volume equal to the upper 10 m of the f j o r d was t r a n s p o r t e d out every f i v e days. T h i s t r a n s p o r t a l s o served to e n t r a i n n u t r i e n t s and introduce "seed s t o c k " from deeper l a y e r s . Takahashi et a_l. (1977) s t u d i e d Saanich I n l e t on Vancouver I s l a n d and found that a f t e r the main diatom bloom there were 10 p e r i o d i c ephemeral summer blooms. These events were the r e s u l t of o c c a s i o n a l wind turbulence which would introduce n i t r a t e and s i l i c a t e i n t o the upper waters, or by freshwater i n t r u s i o n from the F r a s e r R i v e r . Parsons et a_l. (1983) found that t i d a l turbulence i n well-mixed Prevost Passage o u t s i d e Saanich I n l e t was probably r e s p o n s i b l e f o r s u p p l y i n g n i t r a t e to the i n l e t d u r i n g i t s phytoplankton p r o d u c t i o n . There was a p e r i o d i c i t y of 14 days in c h l o r o p h y l l c o n c e n t r a t i o n , with maxima corres p o n d i n g to times of lowest t i d a l h e ight (and t h e r e f o r e lowest t i d a l streaming or t u r b u l e n c e ) . T h i s p e r i o d i c i t y c o i n c i d e d with the lunar c y c l e such that maximal turbu l e n c e o c c u r r e d with s p r i n g t i d e s . The l a g was suggested to be the response time a phytoplankton p o p u l a t i o n takes to u t i l i s e an i n j e c t i o n of n u t r i e n t s and show an i n c r e a s e i n biomass. Balch (1981) found a s i m i l a r phenomenon near Monhegan I s l a n d o f f the coast of Maine, where s p r i n g t i d e s i n c r e a s e d h o r i z o n t a l and v e r t i c a l t u r b u l e n c e , r e s u l t i n g i n an i n c r e a s e i n phytoplankton abundance. Once s t r a t i f i c a t i o n has been e s t a b l i s h e d , i t s e f f e c t on s u c c e s s i o n depends not only on the degree of s t r a t i f i c a t i o n but more importantly on i t s d u r a t i o n . Wind turbulence due to p e r i o d i c storms can d i s t u r b s t r a t i f i c a t i o n enough to allow upward mixing of n u t r i e n t - r i c h water i n t o the euphotic zone. T h i s a c t i o n w i l l have a g r e a t e r e f f e c t on communities which have developed under low n u t r i e n t c o n d i t i o n s . For example, a d i n o f l a g e l l a t e community might have been e s t a b l i s h e d because these organisms can compensate f o r l o w - n u t r i e n t s u r f a c e waters 11 by v e r t i c a l m i g r a t i o n to the n u t r i c l i n e . An i n o c u l a t i o n of n i t r a t e may be s u f f i c i e n t to upset t h i s community i f diatoms are a b l e to u t i l i s e the new source of n i t r a t e . The degree of d i s t u r b a n c e to the s t a b i l i t y of t h i s s u c c e s s i o n a l stage w i l l depend on the l e n g t h of time the p e r t u r b i n g f o r c e p e r s i s t s , the magnitude of the p e r t u r b a t i o n , and the a b i l i t y of any competing organisms to take advantage of the changed c o n d i t i o n s . Thus a storm, depending on i t s degree, may serve to enhance the community which e x i s t s , i n t r o d u c e an e a r l i e r stage of s u c c e s s i o n which soon develops back to the stage before p e r t u r b a t i o n , or a l t e r the stage completely r e s u l t i n g i n a new e q u i l i b r i u m ( G a r r i s o n , 1979; R i c k l e f s , 1973). Another, more r e g u l a r p e r t u r b i n g f o r c e i s that due to t i d e s . The e f f e c t s of a r e g u l a r p e r i o d i c i t y i n t i d a l streaming were mentioned above (Parsons et a l , 1983; B a l c h , 1981). The most i n f l u e n t i a l s t u d i e s on t i d a l e f f e c t s were c a r r i e d out on the c o n t i n e n t a l s h e l f around the United Kingdom. O r i g i n a l l y , Simpson and Hunter (1974) observed temperature d i s c o n t i n u i t i e s i n the I r i s h Sea between well-mixed and s t r a t i f i e d water masses. They assumed d e n s i t y to be a f u n c t i o n of temperature, d i s m i s s i n g s a l i n i t y as a source of buoyancy. At the t r a n s i t i o n between buoyancy gain due to h e a t i n g and l o s s of p o t e n t i a l energy due to t i d a l mixing there i s a f r o n t d e f i n e d by the s t r a t i f i c a t i o n parameter h « u s ~ 3 , where h = water column depth and us = observed s u r f a c e t i d a l v e l o c i t y amplitude. T h i s parameter v a r i e d from 65 to 100 i n f r o n t a l r e g i o n s . S t r a t i f i e d water columns have two p h y s i c a l l y d i s t i n c t 12 communities separated by a p y c n o c l i n e . The upper water community i s n u t r i e n t - p o o r and l i g h t - r i c h while the community below the p y c n o c l i n e i s n u t r i e n t - r i c h and l i g h t - p o o r . There i s some v e r t i c a l t r a n s p o r t between the two l a y e r s , e i t h e r by d i f f u s i o n or t u r b u l e n c e i n the r e g i o n of the p y c n o c l i n e . Pingree et a l . (1978) were ab l e to a c c u r a t e l y p r e d i c t areas which were well-mixed or s t r a t i f i e d , and the l o c a t i o n of the f r o n t a l boundaries between these two c o n d i t i o n s . They used the i n v e r s e of Simpson and Hunter's (1974) s t r a t i f i c a t i o n parameter, s u b s t i t u t i n g average t i d a l v e l o c i t y f o r observed s u r f a c e v e l o c i t y : E = l o g 1 0 [Cd-|u| 3-h" 1] cm 2-s- 3 (2) where, Cd = drag c o e f f i c i e n t = 2.5-10" 3 u = v e r t i c a l l y i n t e g r a t e d M 2 t i d a l v e l o c i t y ( cm«s" 1), overbar denotes average value over one complete t i d a l c y c l e . h = depth of water column (cm) E d e s c r i b e s the energy d i s s i p a t i o n per u n i t mass which takes the value -1.5 i n the t r a n s i t i o n a l f r o n t a l region between well-mixed (E>-1) and w e l l - s t r a t i f i e d (E<-2) water masses. Pingree (1978) d e s c r i b e d the same model but r e t a i n e d Simpson and Hunter's (1974) o r i e n t a t i o n so that the s t r a t i f i c a t i o n parameter i s d e s c r i b e d thus: S = l o g 1 0 [ h - ( C d . I u 1 3 ) " 1 ] (3) In t h i s form, the c r i t i c a l boundary value i s 1.5, while S<1 f o r mixed water and S>2 f o r s t r a t i f i e d water. He a l s o used a s c a l e d depth parameter, Hb, where Hb = water depth/Secchi D i s c depth. These two parameters are p l o t t e d a g a i n s t each other to form an 13 SH-diagram from which one can p r e d i c t s p r i n g phytoplankton development. For l a r g e v a l u e s of S, s t r a t i f i c a t i o n i s most a f f e c t e d by weather; f o r i n t e r m e d i a t e v a l u e s , both weather and t i d e s are important; while f o r low v a l u e s , t i d a l mixing predominates. From c a l c u l a t i o n s , Pingree et a l . (1978) found that mixing by t i d e s was probably more important to phytoplankton d i s t r i b u t i o n s i n summer than wind mixing. The former takes p l a c e predominantly near the bottom while the l a t t e r mostly a f f e c t s the s u r f a c e . Winds would have the g r e a t e s t e f f e c t on f r o n t s where the g r a d i e n t of E/S i s s m a l l , i_.e. , where the t r a n s i t i o n a l zone i s widest, and l i t t l e e f f e c t where g r a d i e n t s are l a r g e . In the well-mixed r e g i o n , diatoms were the most abundant p h y t o p l a n k t e r s . N a n o f l a g e l l a t e s were more abundant in s u r f a c e waters o v e r l y i n g a w e l l - e s t a b l i s h e d t h e r m o c l i n e . Pingree et a l . (1978) were ab l e to p a r t i t i o n the three main p h o t o s y n t h e t i c groups by the degree of temperature s t r a t i f i c a t i o n . In s h e l f areas where the s u r f a c e to bottom AT<3°C, a mixture of diatoms and d i n o f l a g e l l a t e s p r e v a i l e d ; when 3°C < AT < 6°C, d i n o f l a g e l l a t e s dominated; and when AT>6°C, n a n o f l a g e l l a t e s outnumbered a l l other forms. What these groups re p r e s e n t , a c c o r d i n g to the authors, i s a p o t e n t i a l s u c c e s s i o n a l s e r i e s which occurs upon establishment of the t h e r m o c l i n e . The most p r o d u c t i v e regions on the European S h e l f i n summer are a s s o c i a t e d with the f r o n t a l boundary areas where n u t r i e n t s and l i g h t are optimal f o r phytoplankton growth. In s t r a t i f i e d areas the average l i g h t experienced by an a l g a l c e l l i s high but 14 n u t r i e n t s are l i m i t i n g whereas i n mixed waters, n u t r i e n t s are hi g h but l i g h t i s l i m i t i n g . C o m plications a r i s e dependent on v a r i a b l e depths. For i n s t a n c e , when waters are mixed i n an area of i n t e r m e d i a t e depth, the l i g h t i s not l i m i t i n g and n u t r i e n t s may be s u p p l i e d from u p w e l l i n g so that p r o d u c t i o n i s h i g h e s t on the mixed s i d e of the f r o n t . Parsons et a l . (1981) used Pingree's (1978) s t r a t i f i c a t i o n parameter, e x c l u d i n g the drag c o e f f i c i e n t , to expl o r e c h i a p a t t e r n s i n the S t r a i t of Georgia d u r i n g summer. (A number of s t r a t i f i c a t i o n parameter contour maps has been p u b l i s h e d by Stronach,1982, f o r the S t r a i t ) . When the drag c o e f f i c i e n t , Cd, i s excluded (assumed to be c o n s t a n t ) , the parameter w i l l equal -1.0 i n f r o n t a l zones, be l e s s than -1.0 i n t u r b u l e n t waters, and be g r e a t e r than -1.0 i n s t r a t i f i e d waters. Parsons et a l . (1981) found that v a l u e s of the parameter were l e s s than -2 i n t u r b u l e n t passages at e i t h e r end of the S t r a i t . In these areas, h i g h l e v e l s of c h i a occu r r e d due to the i n t r u s i o n of n u t r i e n t - r i c h water e n t e r i n g the S t r a i t . The e f f e c t of t i d a l t u r b u l e n c e i n the north through D i s c o v e r y Passage extended down the west s i d e of the S t r a i t as f a r south as Denman I s l a n d . C h l o r o p h y l l maxima i n the north and south tended to be somewhat on the s t r a t i f i e d s i d e of the c r i t i c a l -1 v a l u e . A p o t e n t i a l source of e r r o r i n the above model i s the assumption that heat f l u x i s the s o l e source of water buoyancy, whereas freshwater r u n o f f from the Fr a s e r River i s a major c o n t r i b u t o r to s t r a t i f i c a t i o n i n the S t r a i t of Georgia, e s p e c i a l l y i n the south. A f a i r amount of t u r b i d i t y due to s i l t 1 5 i s a s s o c i a t e d with t h i s freshwater l e n s . Thus the e x t i n c t i o n c o e f f i c i e n t s are s i g n i f i c a n t l y higher than those found i n the C e l t i c Sea. Parsons et a l . (1981) noted that n o r t h of Texada I s l a n d c h l o r o p h y l l f l u o r e s c e n c e was s i g n i f i c a n t l y c o r r e l a t e d to s u r f a c e temperature. One would thus expect the s t r a t i f i c a t i o n parameter to be a b e t t e r p r e d i c t o r of c h l o r o p h y l l i n the northern S t r a i t of Georgia. Few s t u d i e s on phytoplankton have been undertaken i n the northern S t r a i t of Georgia and these were part of l a r g e r p r o j e c t s l o o k i n g at the S t r a i t as a whole (see the review by H a r r i s o n et a l . , 1983). Stephens e_t a_l. (1969) presented a few seasonal maps of Skeletonema costatum, Ditylum b r i g h t w e l l i i , and R h i z o s o l e n i a s t o l t e r f o t h i i . Parsons e_t a l . - (1981), as p r e v i o u s l y d e s c r i b e d , found areas of high c h i a a s s o c i a t e d with the t i d a l l y - a c t i v e northern passages which they a t t r i b u t e d to diatom biomass. The study was l i m i t e d to a time of f a i r l y w e l l - e s t a b l i s h e d s t r a t i f i c a t i o n and only at the s u r f a c e l a y e r . The northern S t r a i t of Georgia (herein d e s i g n a t e d NSG) was s e l e c t e d f o r the present study because i t promised a v a r i e t y of mixing regimes i n which to examine phytoplankton communities. On the west s i d e (Vancouver I s l a n d s i d e ) the D i s c o v e r y Passage t i d a l j e t has been shown to have a marked i n f l u e n c e on n u t r i e n t regimes ( P r i c e e_t a_l., 1985) due to t u r b u l e n t mixing p r o c e s s e s . The east s i d e has been shown to be i n f l u e n c e d by the F r a s e r River plume ( T u l l y and Dodimead, 1957; Mackas et a_l., 1980). T h e r e f o r e , one would expect the east si d e to be more s t r a t i f i e d than the west due to s a l i n i t y f l u x and lower t i d a l t u r b u l e n c e . 16 The hypothesis put forward was that diatoms w i l l dominate on the t i d a l l y - m i x e d west s i d e while n a n o f l a g e l l a t e s and d i n o f l a g e l l a t e s w i l l p r e f e r the s t r a t i f i e d east s i d e . Adjacent to the NSG l i e s a smal l complex of i n l e t s , termed the Malaspina Complex (designated MC) which was thought to be an even more s t r a t i f i e d regime due to i t s s h e l t e r e d nature. T h i s complex was in c l u d e d i n the study f o r comparison. A l s o explored i n the t h e s i s i s phytoplankton community response to depth. Most p r e v i o u s s t u d i e s have been l i m i t e d to phytoplankton as a whole and o f t e n only at a s i n g l e depth. Foremost i n s t u d i e s on c h l o r o p h y l l maxima and depth d i s t r i b u t i o n s are those of C u l l e n et a l . (1982) and Reid et a l . (1978) who have performed e x t e n s i v e s t a t i s t i c a l a n a l y ses of the s t r u c t u r e of phytoplankton communities at v a r i o u s d i s t a n c e s o f f the c o a s t of southern C a l i f o r n i a . They have e f f e c t i v e l y d e s c r i b e d how communities compare w i t h i n the c h l o r o p h y l l maximum and w i t h i n surface l a y e r s , as w e l l as between the two depths. For the NSG, the hypothesis was t h a t , with respect to depth, communities w i l l vary more i n s t r a t i f i e d waters with f l a g e l l a t e d forms more abundant i n s u r f a c e l a y e r s and diatoms deeper down. 17 2. METHODS 2.j_ Study S i t e s j2«l»l Northern S t r a i t of Georgia The northern S t r a i t of Georgia l i e s i n a roughly NW-SE d i r e c t i o n between 49°42'N and 50°02'N l a t i t u d i n a l l y and between 124°32'W and 125°10'W l o n g i t u d i n a l l y . For the sake of c l a r i t y , t h i s t h e s i s d e s c r i b e s the main a x i s (34 km) of the S t r a i t as running north-south and the c r o s s - s t r a i t a x i s (26 km) as being east-west. The study area i t s e l f approximates a r e c t a n g l e bounded on the north by Quadra, Marina, and C o r t e s I s l a n d s , on the south by a l i n e from Cape Lazo to Powell R i v e r , on the east by the mainland and Malaspina P e n i n s u l a , and on the west by Vancouver I s l a n d ( F i g . 1). Within the study area are three main i s l a n d s (Hernando, Savary, and Harwood) and numerous sma l l e r i s l a n d s such as Twin, M i t l e n a t c h , and the Copeland group. A l s o w i t h i n the area are a few r e e f s (Grant and M y s t e r y ) . The depth of the S t r a i t v a r i e s c o n s i d e r a b l y from shallow s h o a l s to the deep c e n t r a l b a s i n (^ 300 m). The p h y s i c a l oceanography of the S t r a i t of Georgia i s d e s c r i b e d i n some d e t a i l by both T u l l y and Dodimead (1957) and Waldichuk (1957) from which the f o l l o w i n g d e s c r i p t i o n i s p i e c e d together f o r the NSG. During winter (mid-September to m i d - A p r i l ) winds are predominantly from the southeast while i n summer, n o r t h w e s t e r l i e s p r e v a i l . In the southern S t r a i t winds are c y c l o n i c , as are wind-driven c u r r e n t s , whereas winds i n the NSG appear to be u n i d i r e c t i o n a l depending on the season. The e a s t e r n LEGEND N.Strait of Georgia Cape Lazo Comox Baynes Sound Denman Island Texada Island Malaspina S t r a i t Powell River Harwood Island Savary Island Hernando Island Copeland Group Malaspina Peninsula Coode Peninsula Malaspina Inlet Okeover Inlet Lancelot Inlet Theodosia Inlet Desolation Sound Twin Islands Cortes Island Marina Island S u t i l Channel Quadra Island Cape Mudge Discovery Passage Campbell River Mitlenatch Island 19 s i d e i s s u b j e c t e d to stronger winds. T u l l y and Dodimead (1957) suggested that d u r i n g SE winds, water i s f l u s h e d out through the northern passages while f l u s h i n g i s out through the south d u r i n g NW winds. Taking i n t o account the c r o s s - s e c t i o n a l area of c r i t i c a l p o i n t s i n the northern passages and i n the southern entrances to the S t r a i t , Waldichuk (1957) assumed that most of the f l u s h i n g must be through the south. The above authors suggested that s t r a t i f i e d waters enter the northern passageways from the S t r a i t . They are mixed to homogeneity and re t u r n e d to the S t r a i t . The NSG experiences two f l o o d i n g t i d e s , one from the north and the other from the south, which meet somewhere near Cape Lazo. On a f l o o d t i d e , water flows southward from Discovery Passage to Cape Lazo. The t i d e from the south flows northward at a l l p o i n t s a c r o s s the S t r a i t . Where they meet, both flows are d e f l e c t e d to the e a s t . There i s a l s o a flow northward through S u t i l Channel and D e s o l a t i o n Sound. As the f l o o d d i e s down, the i n f l u e n c e of the west-side t i d a l j e t weakens and most of the flow i n the NSG i s northwards. Upon ebbing, the t i d a l flow through D i s c o v e r y Passage becomes northward and f a i r l y s trong (>1.6 km'h"-1 ) whereas waters i n the NSG show a very confused p a t t e r n . E v e n t u a l l y waters flow southward from S u t i l Channel and D e s o l a t i o n Sound and throughout most of the NSG, the only d i f f e r e n t flow being northward through D i s c o v e r y Passage. For each s t a t i o n the t i d a l c u r r e n t d i r e c t i o n has been 20 determined f o r the time of sampling from t i d a l models (Canadian Hydrographic S e r v i c e , 1983) to get a rough idea of h o r i z o n t a l water t r a n s p o r t ( F i g . 2). I t was assumed r e s i d u a l flows would be minimal over the two days r e q u i r e d to sample the study a r e a . As t i d a l c u r r e n t s i n the NSG are u n i f o r m l y < 0.4 km«h~ 1 (Can. Hydrogr. Serv., 1983) and as the average time between s t a t i o n s was 1 h, a water body would have t r a v e l l e d 0.4 km and thus would not be "resampled". In f a c t , d u r i n g a maximum-flood t i d a l c y c l e of 8 h, a p a r c e l of water would have only t r a v e l l e d 3.2 km which i s s t i l l l e s s than i n t e r - s t a t i o n d i s t a n c e s of 6.5-8.5 km. The stages of the spring-neap t i d a l c y c l e d u r i n g samplings are a v a i l a b l e i n Haigh (1988). A g r i d was set up such that t r a n s e c t s ran a c r o s s the S t r a i t , each having f i v e s t a t i o n s along i t s l e n g t h . The s t a t i o n s were evenly spaced so that each t r a n s e c t c o n t a i n e d two near-shore s t a t i o n s , one s t a t i o n m i d - S t r a i t , and two s t a t i o n s between m i d - S t r a i t and e i t h e r shore. Transect 1 was southernmost, Transect 5 northernmost. During 1986, sampling was undertaken f i v e times, the f i r s t t hree (March 18-19, A p r i l 22-23, and June 25-26) aboard the C.S.S. V e c t o r , the l a s t two (August 12-13 and September 16-17) aboard the C.S.S. R e v i s o r . Due to the behaviour of c e r t a i n phytoplankton s p e c i e s , notably v e r t i c a l l y m i g r a t i n g d i n o f l a g e l l a t e s , sampling was always done duri n g the d a y l i g h t hours i n an e f f o r t to minimise some of the v a r i a t i o n due to d i e l p e r i o d i c i t y . Environmental ( i n c l u d i n g CTD values) and b i o l o g i c a l data are a v a i l a b l e i n Haigh (1988). June 25-26 22 2.J_.2 Malaspina Complex The Malaspina Complex i s comprised of three i n l e t s : Malaspina, Okeover, and L a n c e l o t . Malaspina I n l e t connects the complex to D e s o l a t i o n Sound, running i n the same d i r e c t i o n as the NSG but on the other s i d e of Malaspina P e n i n s u l a . Okeover i s b a s i c a l l y an extension of Malaspina, a l s o running p a r a l l e l to the NSG, but i s p a r t i a l l y cut o f f from Malaspina by Coode P e n i n s u l a . J o i n i n g these two i n l e t s at a 45° angle to Malaspina i s L a n c e l o t I n l e t , running north-south. At the j u n c t i o n of these three i n l e t s i s the deepest part of the complex where a depth of 134 m i s reached. Malaspina i s f a i r l y shallow (50 m) whereas the other two range from 60-80 m. S t a t i o n s were set up such that each i n l e t had One s t a t i o n at i t s end and one i n the middle. The seventh s t a t i o n was p l a c e d at the j u n c t i o n of the three i n l e t s ( F i g . 1). Environmental and b i o l o g i c a l data f o r t h i s r e gion are a v a i l a b l e i n Haigh (1988). 2.2 Pump Sampling System The sampling system c o n s i s t e d of a diaphragm pump connected by the intake v a l v e to a 20 m hose ( r e - e n f o r c e d 2.5 cm diameter) which would b r i n g up water from depth. The water was passed from the pump to a bubble t r a p , then through a Turner 111 fluorometer connected to a ch a r t r e c o r d e r . The end of the sampling hose was attac h e d to a weighted winch l i n e t h a t was lowered down to 20 m at a constant slow speed. Taking i n t o account a l a g time (time water takes to pass from the hose opening, through the system, 23 to the f l u o r o m e t e r ) , determined from an i n j e c t e d c h l o r o p h y l l s p i k e , one c o u l d get a f l u o r o m e t r i c p r o f i l e of the 20 m water column and the depth of the c h l o r o p h y l l maximum. As a matter of convention, samples were always taken at 0 and 20 m, p l u s two i n t e r m e d i a t e depths depending on the f l u o r o m e t r i c t r a c e . Samples were drawn from the o u t l e t hose once the water had passed through the fluorometer, p e r m i t t i n g a match of r e l a t i v e f l u o r e s c e n c e with a p a r t i c u l a r sample. Sampling was done on the r e t u r n to the s u r f a c e from lower depths. Thus, from each s t a t i o n , four samples of water were obtained which were taken to the s h i p ' s l a b o r a t o r y f o r immediate p r o c e s s i n g as f o l l o w s . 2.3 N i t r a t e With a 60 ml s y r i n g e , 50 ml of the seawater sample was taken up and a Swinnex f i l t e r h o l d e r , c o n t a i n i n g a precombusted (at 480°C f o r 5 h) g l a s s f i b r e (GF/F) 2.5 cm diameter f i l t e r , was a t t a c h e d . The seawater was then pushed very g e n t l y through the f i l t e r so that the c e l l s would be entrapped without r u p t u r i n g and thereby r e l e a s i n g n u t r i e n t s . T h i s f i r s t 50 ml was used as a wash for both the 30 ml Nalgene sample b o t t l e s and the f i l t e r apparatus. The Swinnex holder was then removed and a f u r t h e r 50 ml of seawater taken up. The f i r s t 20 ml was used as a f u r t h e r wash and the l a s t 30 ml c o l l e c t e d f o r n u t r i e n t a n a l y s i s . The sample b o t t l e s were immediately p l a c e d i n the f r e e z e r to a v o i d b a c t e r i a l a c t i v i t y u n t i l a n a l y s i s back i n the l a b . N i t r a t e a n a l y s i s was done on an Auto-Analyzer. The n i t r a t e 24 i s reduced to n i t r i t e by passin g the sample through a cadmium column (Wood et a l . , 1967). T h i s n i t r i t e i s f u r t h e r reduced with s u l f a n i l a m i d e then N-(1-naphthyl)-ethylenediamine to produce a red dye t h a t r e f l e c t s the n i t r i t e c o n c e n t r a t i o n by i t s c o l o u r . T h i s dye runs through a spectrophotometer which measures the o p t i c a l d e n s i t y at a wavelength of 540 nm. As the above method a c t u a l l y measures n i t r i t e , r e s u l t s r e f l e c t both the n i t r a t e and n i t r i t e c o n c e n t r a t i o n s . One assumes n i t r i t e i s n e g l i g i b l e . U s u a l l y , four standards were made (5,10,20,30 uli N0 3) with 3% NaCl as the base. The r e s u l t a n t o p t i c a l d e n s i t i e s were then reg r e s s e d on n i t r a t e c o n c e n t r a t i o n s and the r e g r e s s i o n l i n e used to c a l c u l a t e the sample N0 3 c o n c e n t r a t i o n s . N i t r a t e data are a v a i l a b l e i n Haigh (1988). 2.4 C h l o r o p h y l l For each depth at each s t a t i o n , 250 ml of sample seawater was vacuum f i l t e r e d through a Whatman GF/F 4.7 cm g l a s s f i b r e f i l t e r . To prevent the rupture- of c e l l s , and subsequent l o s s of c h l o r o p h y l l , no more than 10 mm Hg pressure was used. Parsons et a l . (1984) suggest a p p l y i n g a few drops of MgC0 3 to reduce c h l o r o p h y l l degradation; however, Holm-Hansen and Reimann (1978) found t h a t t h i s r e s u l t s i n slower f i l t r a t i o n r a t e s and l o s s of phaeopigments by a d s o r p t i o n onto MgC0 3. They a l s o found no s i g n i f i c a n t l o s s of c h l o r o p h y l l a without MgC0 3. The MgC0 3 s o l u t i o n was not used i n t h i s study. Once the water had f i l t e r e d through, the d i s c with entrapped c e l l s was f o l d e d in h a l f and placed i n t o an a c e t a t e 25 envelope normally used f o r photographic n e g a t i v e s . The d i s c was then p l a c e d i n t o a d e s i c c a t o r ( p a i l with D r i e r i t e ) and f r o z e n immediately to prevent degradation of the c h l o r o p h y l l . Holm-Hansen and Reimann (1978) maintained that f r o z e n c h l o r o p h y l l samples remain u n a l t e r e d f o r a l e a s t 3 weeks a f t e r c o l l e c t i o n . Back in the l a b , the frozen samples were ground i n 3 ml of 90% acetone (over i c e with the l i g h t s out) f o r 30-60 s. A f u r t h e r 6 ml of 90% acetone was added to the pulp and the e x t r a c t i o n mixture was f i l t e r e d through f r i t t e d g l a s s to r i d the acetone with c h l o r o p h y l l of the g l a s s f i b r e s . The e x t r a c t e d c h l o r o p h y l l was t r a n s f e r r e d to a c e t o n e - r i n s e d c u v e t t e s and s t o r e d i n the r e f r i g e r a t o r t i l l a batch of ten to twenty was completed. The c h l o r o p h y l l was measured u s i n g a Turner Designs fluorometer with a Corning CS 5-60 e x c i t a t i o n f i l t e r and a Corning CS 2-64 emission f i l t e r . The l a t t e r serves to measure mostly c h i a by absorbing only 10% of the l i g h t f l u o r e s c e d by c h i a but over 80% of the l i g h t f l u o r e s c e d by c h i c (Holm-Hansen et a l . , 1965). To c o r r e c t f o r phaeopigments, a l l the c h l o r o p h y l l was degraded to phaeopigments by adding 2 drops of 10% HC1 to each cuvette (Parsons et a l . , 1984). A f t e r the c u v e t t e s had been shaken and allowed to stand f o r a t l e a s t 30 s, a second reading was taken. The r e s u l t a n t drop i n the reading, termed the " a c i d f a c t o r " , has been r e p o r t e d as 1.6-1.8 f o r h e a l t h y marine phytoplankton c u l t u r e s by Yentsch and Menzel (1963). Holm-Hansen et a l . (1965) found that the a c i d f a c t o r v a r i e d among s p e c i e s 26 and n a t u r a l p o p u l a t i o n s (e.g., from 0.9 i n an ocean sample from 2,500 m depth to 3.0 i n a l a b o r a t o r y c u l t u r e of C o c c o l i t h u s  h u x l e y i ) . The l a t t e r authors a l s o found that c h o i c e of emission f i l t e r s can a f f e c t the f a c t o r . The a c i d f a c t o r s used i n t h i s r e p o r t were 3.26 f o r f l u o r o m e t r i c readings l e s s than or equal to 53 (before a c i d a d d i t i o n ) , and 3.18 f o r readings g r e a t e r than 53. A f t e r r e p a i r s to the fluorometer, the a c i d f a c t o r s were 3.26 f o r readings l e s s than or equal to 298, and 3.16 f o r readings g r e a t e r than 298. The equations to convert these f l u o r o m e t r i c readings to c h l o r o p h y l l values were m o d i f i c a t i o n s of Parsons e_t a l . 's (1984) equations. Where they used "door f a c t o r s " f o r the Turner 111 fluorometer, t h i s r e p o r t uses a d i r e c t r e g r e s s i o n of f l u o r o m e t r i c readings on measured pure c h i a c o n c e n t r a t i o n s . The r e g r e s s i o n was n o n - l i n e a r over a wide range of c h l o r o p h y l l v a l u e s (0-1000 mg c h i a «1~ 1) and was best f i t t e d by d i f f e r e n t r e g r e s s i o n l i n e s at d i s c r e t e i n t e r v a l s . The r e s u l t i n g equations were thus: (1) Before Repairs (a) T<=53 Chi a /Phaeo = (1.75 (b) 53<T<=250 Chi a /Phaeo = (2.29 (c) T>250 Chi a /Phaeo = (2.29 x T + 0.082) x Vac/Vsw x T + 107) x Vac/Vsw x T +107) x Vac/Vsw 27 (2) A f t e r Repairs (a) T<=298 Chi a /Phaeo = (1.35 x T - 0.851) x Vac/Vsw (b) T>298 Chi a /Phaeo = (1.01 x T + 75.3) x Vac/Vsw where: T = (AF/(AF-1)) x (Rb-Ra) f o r c h l o r o p h y l l a T = (AF/(AF-1)) x (AFxRa-Rb) f o r phaeopigments Rb = F l u o r o m e t r i c reading before a c i d a d d i t i o n Ra = F l u o r o m e t r i c reading a f t e r a c i d a d d i t i o n AF = A c i d f a c t o r Vac = Volume acetone used f o r e x t r a c t i o n (L) Vsw = Volume seawater f i l t e r e d (L) C h l o r o p h y l l data are a v a i l a b l e i n Haigh (1988). 2.5 Phytoplankton For c e l l counts, 125 ml of seawater was preserved with Lugol's S o l u t i o n (with a c e t i c a c i d ) . These samples were s e a l e d with e l e c t r i c i a n ' s tape and s t o r e d i n the dark- u n t i l a n a l y s i s . A n a l y s i s e n t a i l e d s e t t l i n g e i t h e r 10 or 50 ml of sample seawater, depending on the estimated biomass based on the f l u o r e s c e n c e p r o f i l e s . The Utermohl or i n v e r t e d microscope method (see Halse, 1978) was employed. Paasche (1960) noted that a problem when using 50 ml chambers i s that Chaetoceros spp. do not always s e t t l e , presumably due to thermal c u r r e n t s w i t h i n the column or adhesion to the chamber w a l l s . When 10 ml was s e t t l e d , the columns were l e f t f o r 24 hours; when 50 ml s e t t l e d , they were l e f t f o r 48 hours. 28 Venrick (1978) presented a d e t a i l e d account of how many c e l l s to count and the t h e o r e t i c a l c o n s i d e r a t i o n s behind v a r i o u s methods. Acco r d i n g to Lund et a l . (1958), counting 100 c e l l s i n t o t a l g i v e s a p r e c i s i o n of ± 20% while counting 400 c e l l s g i v e s ± 10%. Holmes and Widrig (1956) e x p l o r e d the p r e c i s i o n of abundance estimates by the Utermohl sedimentation method and found the degree of p r e c i s i o n i s a f u n c t i o n of the number of organisms counted. They suggested counting a minimum of 15-30 specimens of any one organism. A l s o , i n d i v i d u a l s of chain-forming s p e c i e s are not s e l e c t e d at random from the o r i g i n a l sample so that although the accuracy f o r these s p e c i e s i n c r e a s e s with i n c r e a s i n g numbers counted, i t does so at a slower r a t e than f o r the s i n g l e - c e l l e d s p e c i e s . Another p o i n t brought out by Holmes and W i d r i g (1956) i s that d i s t r i b u t i o n s i n nature are non-homogeneous, t h e r e f o r e one should sample a s p e c i f i c area more than once (take r e p l i c a t e samples). These e x t r a samples need not add to the burdensome task of c o u n t i n g as they can be q u a n t i t a t i v e l y combined before enumeration. Plankton i d e n t i f i c a t i o n was performed to s p e c i e s l e v e l wherever p o s s i b l e . References used f o r diatom i d e n t i f i c a t i o n i n c l u d e d Cupp (1943), Brunei (1962), Hendey (1964), Shim (1977), and Hustedt (1985). References f o r d i n o f l a g e l l a t e s were S c h i l l e r (1933,1937), Abe (1981), and Dodge (1982), while n a n o f l a g e l l a t e r e f e r e n c e s i n c l u d e d Buchanan (1966) and Watanabe (1976). Due to the l a r g e s i z e range of the organisms i n v o l v e d , counting was done at three l e v e l s of m a g n i f i c a t i o n . For the n a n o f l a g e l l a t e s , random f i e l d s at high power (500x) were counted 29 u n t i l approximately 200 c e l l s i n t o t a l were seen. The only p i c o p l a n k t e r enumerated was Micromonas p u s i l l a as c y a n o b a c t e r i a appeared to be r e l a t i v e l y sparse. The common l a r g e r organisms such as diatoms were counted by employing a g r i d of 45 f i e l d s of medium power (200x) which covered most areas of the counting chamber bottom. Species that were e s p e c i a l l y numerous were only counted u n t i l t h e i r t o t a l reached 200. F i n a l l y , f o r the l a r g e r and/or rare s p e c i e s , the e n t i r e chamber bottom was scanned at low power (78.75x). For the sake of e a s i e r data m a n i p u l a t i o n a l l species/groups were coded as presented i n Table 1. These codes are used e x t e n s i v e l y i n f o l l o w i n g t a b l e s . C e l l c o n c e n t r a t i o n s are a v a i l a b l e i n Haigh (1988). 2.6 Volume to Carbon Conversion C e l l counts were converted to biomass, expressed as c e l l carbon, which has been found to be more e c o l o g i c a l l y meaningful i n p r o d u c t i v i t y experiments (Wujek, 1966; Smayda, 1978). In t h i s study biomass allows comparison amongst s p e c i e s groups as w e l l as organismal groups. C o n t r i b u t i o n s to standing stock are more r e a d i l y apparent. Paasche (1960) used l i n e a r r e g r e s s i o n a n a l y s i s to argue f o r the use of c e l l s u r f a c e area r a t h e r than c e l l number or c e l l volume as the best p r e d i c t o r of s t a n d i n g stock. C e l l numbers, he suggested, w i l l over-emphasise the r o l e played by small c e l l s while c e l l volumes w i l l over-emphasise the importance of l a r g e forms. The t r a n s f o r m a t i o n to c e l l carbon f i r s t e n t a i l e d the measuring of c e l l dimensions so that a volume c o u l d be a t t a i n e d . Where p o s s i b l e , at l e a s t ten c e l l s per 30 TABLE 1. Species Codes Actund = Actinoptychus undulatus Alexan = Alexandrium o s t e n f e l d i i Amph i d = Amphidinium spp. Apedin = A p e d i n e l l a s p i n i f e r a A s t g l a = A s t e r i o n e l l a g l a c i a l i s B a l l o o u n i d e n t i f i e d d i n o f l a g e l l a t e B i d l o n = O d o n t e l l a l o n g i c r u r i s C e n t r i = u n i d e n t i f i e d c e n t r i c diatoms C e r a t i = Ceratium spp. Chacnv = Chaetoceros convolutus Chacom Chaetoceros compressus Chacst = Chaetoceros c o n s t r i c t u s Chadeb = Chaetoceros d e b i l i s Chadec = Chaetoceros d e c i p i e n s Chaeib = Chaetoceros e i b e n i i Chaeto = Chaetoceros spp. Chalac — Chaetoceros l a c i n i o s u s Chasoc = Chaetoceros s o c i a l i s Choano = C h o a n o f l a g e l l a t e s Chryso = Chrysochromulina spp. C i l i a t = H e t e r o t r o p h i c c i l i a t e s C o r c r i = Corethron c r i o p h i l u m Corymb = Corymbellus aureus C o s c i n = C o s c i n o d i s c u s spp. Coswai = C o s e i n o d i s c u s w a i l e s i i Crypto = cryptomonads C y l i n d = C y l i n d r o t h e c a spp. Detpum = Detonula pumila D i c r a t D i c r a t e r i a sp. Dicspe D i c t y o c h a speculum Dinobr = Dinobryon sp. Dinoph Dinophysis spp. D i p l o p = d i p l o p s a l o i d s Dispse = Dissodinium pseudolunula D i t b r i = Ditylum b r i g h t w e l l i i Ebr i a = E b r i a t r i p a r t i t a E n s i c u = E n s i c u l i f e r a sp. Euczoo = Eucampia zoodiacus Eutrep = E u t r e p t i e l l a spp. F r a g i l = F r a g i l a r i a spp. Fuzzba = u n i d e n t i f i e d c i l i a t e Glenod = u n i d . t h e c a t e d i n o f l a g e l l a t e s Gonyau = Gonyaulax spp. Gramar = Grammatophora marina Gymnod = gymnodinoids Gyrodi = Gyrodinium spp. Hetaka = Heterosigma akashiwo Hetmas = Heteromastix sp. H e t t r i = Heterocapsa t r i q u e t r a 31 TABLE 1. (Cont'd) Katodi = Katodinium rotundatum K o f v e l = K o f o i d i n i u m v e l l e l o i d e s Leptoc = L e p t o c y l i n d r u s spp. Licmop = Licmophora spp. Melmon = M e l o s i r a m o n i l i f o r m i s Mesrub = Mesodinium rubrum Micrac = Micracanthodinium sp. M i c r o f = u n i d e n t i f i e d n a n o f l a g e l l a t e s Microm = Micromonas p u s i l l a Navicu = n a v i c u l o i d s Nitpac = N i t z s c h i a p a c i f i c a N i t z s c = N i t z s c h i a spp. Nocsc i = N o c t i l u c a s c i n t i l l a n s Ochrom = Ochromonas sp. Odoaur = O d o n t e l l a a u r i t a Oxyoxy = Oxyphysis oxytoxoides P a r s u l = P a r a l i a s u l c a t a Pennat = u n i d e n t i f i e d pennate diatoms Ple u r o = Pleurosigma/Gyrosigma spp. Polkof = P o l y k r i k o s k o f o i d i i Procat = Protogonyaulax c a t e n e l l a Progrc = Prorocentrum g r a c i l e Protam = Protogonyaulax tamarensis Protop = P r o t o p e r i d i n i u m spp. Pyrami = Pyramimonas spp. R h i d e l = R h i z o s o l e n i a d e l i c a t u l a Rhi f r a = R h i z o s o l e n i a f r a g i l i s s i m a R h i s e t = R h i z o s o l e n i a s e t i g e r a R h i s t o = R h i z o s o l e n i a s t o l t e r f o t h i i Rhizos = R h i z o s o l e n i a sp. S c r i p p = S c r i p p s i e l l a t r o c h o i d e a Skecos = Skeletonema costatum S t e n i p = Stephanopyxis n i p p o n i c a S t e t u r = Stephanopyxis t u r r i s T e t r a s = T e t r a s e l m i s spp. Thaaes = T h a l a s s i o s i r a a e s t i v a l i s Thaags = T h a l a s s i o s i r a a n g s t i i Thaang = T h a l a s s i o s i r a a n g u s t e - l i n e a t a Thaecc = T h a l a s s i o s i r a e c c e n t r i c a T h a f r a = T h a l a s s i o t h r i x f r a u e n f e l d i i Thalas = T h a l a s s i o s i r a spp. Than i t = Thalassionema n i t z s c h i o i d e s Thanor = T h a l a s s i o s i r a n o r d e n s k i o e l d i i Tharot = T h a l a s s i o s i r a r o t u l a T r o l e p = T r o p i d o n e i s l e p i d o p t e r a Unknow = u n i d e n t i f i e d f l a g e l l a t e s Z o o f l a = z o o f l a g e l l a t e s 32 sp e c i e s were measured, however, due to the r a r i t y of some sp e c i e s fewer c e l l s were used, and i n some cases, estimates from the l i t e r a t u r e had to s u f f i c e . Some c e l l s have p e r f e c t geometric volumes (e.g., C o s c i n o d i s c u s ) which are easy to c a l c u l a t e . Other s p e c i e s take on more b i z a r r e forms such as P r o t o p e r i d i n i u m depressum. In these cases the c e l l s were approximated to the nearest geometric volumes such as e l l i p s o i d s . No doubt e r r o r i s int r o d u c e d here, as mentioned by Paasche (1960) who found an extreme example where the Chaetoceros d e b i l i s t o t a l c e l l volume of a whole p o p u l a t i o n was overestimated by 100%. F o l l o w i n g are the volumes used and t h e i r equations: (1) C y l i n d e r (2) Squashed c y l i n d e r (3) Spheroid (4) E l l i p s o i d (5) Rectangular box (6) T r i a n g u l a r box (7) Cone V = (L x ir x d 2 ) / 4 V = (L x 7T x d 1 x d2)/4 V = (tr x d 3 ) / 6 V = (L x 7T x d 2 ) / 6 V = L x w x h V = (L x w x h)/2 V = (h x 7r x d 2 ) / l 2 where; L = l e n g t h (um) w = width (txm) d = diameter (um) h = height (am) Volume equations are a l s o presented i n E d l e r (1979). The equations used i n t h i s study f o r c o n v e r t i n g c e l l volume to carbon were e x t r a c t e d from v a r i o u s sources. Strathman (1967) 33 g i v e s two equations, one f o r diatoms and one from other phytoplankton. The reason f o r s e p a r a t i n g out diatoms i s that these organisms have l a r g e vacuoles which are not c o n t r i b u t i n g to carbon content. In f a c t , Strathman (1967) found that plasma volume would g i v e a more p r e c i s e estimate of c e l l carbon but t h i s volume i s hard to measure. His equations are thus: (1) Diatoms: l o g C = 0.758 x l o g V - 0.422 (2) Other Phytoplankton: l o g C = 0.866 x l o g V - 0.460 where: C = pg O c e l l " 1 V = /xm 3«cell" 1 ( o r d i n a r y volume) Eppley et §_1. (1970) presented s i m i l a r c o n v e r s i o n equations to those above as d i d Taguchi (1976) f o r diatoms. E d l e r (1979) presented simple l i n e a r c o n v e r s i o n s . A f t e r a long search, i t was found that there were no r e a l equations f o r c o n v e r t i n g volume to carbon f o r h e t e r o t r o p h i c d i n o f l a g e l l a t e s or even n a n o f l a g e l l a t e s . Most authors tend to use phytoplankton equations when e s t i m a t i n g h e t e r o t r o p h i c c e l l carbon (e.g., Reid et a l . , 1970). T h i s author had no o p t i o n but to do the same. The l a r g e d i n o f l a g e l l a t e s N o c t i l u c a and Ko f o i d i n i u m a l s o present problems as to use t h e i r apparent volumes g r o s s l y over-estimates carbon content. These d i n o f l a g e l l a t e s c o n s i s t mostly of a f l u i d - f i l l e d vacuole with accumulated l i g h t e r ions such as. Na + r e l a t i v e to K +, and NH a ( K e s s e l e r , 1966). Dewey (1976) presented a graph of c e l l carbon vs c e l l diameter f o r N o c t i l u c a m i l i a r i s (= s c i n t i l l a n s ) from which t h i s author has 34 e x t r a c t e d v a l u e s and c a l c u l a t e d a new r e g r e s s i o n of c e l l carbon vs c e l l volume, presented below: log C = 1.60 x l o g V - 8.98 r 2 = 0.364 where: C = pg O c e l l " 1 V = M m 3 • c e l l " 1 L a s t l y , an equation f o r c i l i a t e s was needed as these organisms had been enumerated under t h i s general category. Mesodinium rubrum was kept separate as i t c o n t a i n s p h o t o s y n t h e t i c endosymbionts ( T a y l o r et a l . , 1969; T a y l o r et a l . , 1971; Blackbourn et a l . , 1973; Oakley & T a y l o r , 1978) and can c o n t r i b u t e g r e a t l y to l o c a l primary p r o d u c t i v i t y (Lindholm, 1985). Again, e x t r a c t e d data were used to c a l c u l a t e a general c o n v e r s i o n equation. Beers & Stewart (1970) s t u d i e d microzooplankton and one of t h e i r groups was " C i l i a t a other than T i n t i n n i d a " which c o n s i s t e d mostly of Strombidium s p e c i e s (as was the case i n the present data) with an average volume of 1800 M m 3 . From t a b l e s of average numerical abundance and organic carbon from three nearshore s t a t i o n s o f f La J o l l a , the average c e l l carbon was 399 pg O c e l l " 1 . The equation i s thus: C(pg O c e l l " 1 ) = 0.22 x V ( u m 3 - c e l l " 1 ) T h i s r e s u l t s i n a s i g n i f i c a n t d i s c r e p a n c y with the c i l i a t e c o n v e r s i o n value i n E d l e r (1979) who r e p o r t e d a value e x a c t l y h a l f of that above (0.11). For the m u l t i v a r i a t e s t a t i s t i c s used here, t h i s d i f f e r e n c e i n p o s s i b l e biomass i s not important 35 because changes i n v a r i a n c e are u t i l i s e d . However, f o r biomass d i s t r i b u t i o n a l s t u d i e s i n t h i s r e p o r t , one must keep i n mind that a biomass o v e r e s t i m a t i o n f o r the c i l i a t e s i s p o s s i b l e . For comparisons with s t u d i e s using the B a l t i c Sea c o n v e r s i o n of c i l i a t e volume to biomass, one should halve the values r e p o r t e d here. Biomass c o n c e n t r a t i o n s f o r organisms s t u d i e d are a v a i l a b l e i n Haigh (1988). 36 3. RESULTS 3_.J_ Depth-Location A n a l y s i s v i a Canonical C o r r e l a t i o n 3_.J_.J_ M u l t i v a r i a t e S t a t i s t i c s T h i s t h e s i s makes use of a few m u l t i v a r i a t e techniques which allow the manipulation of the l a r g e amounts of data o f t e n obtained i n phytoplankton f i e l d s t u d i e s . A l l data analyses and gr a p h i c s were performed by the B i o s c i e n c e s Data Centre's VAX-11/750 minicomputer running the Berkeley UNIX 4.3 o p e r a t i n g system. The s t a t i s t i c a l package used i s simply c a l l e d "S" (Becker & Chambers, 1984). P r i n c i p a l Components A n a l y s i s (PCA) i s p a r t i c u l a r l y u s e f u l as i t reduces the d i m e n s i o n a l i t y of a d a t a s e t . Some u s e f u l r e f e r e n c e s on PCA are B l a c k i t h & Reyment (1971), Pimentel (1979), and Se a l (1964). In essence, the data are p l a c e d i n t o n-dimensional space using the o r i g i n a l v a r i a b l e s (phytoplankton s p e c i e s ) as the axes so that a c l o u d of p o i n t s r e s u l t s . Using matrix a l g e b r a , the s t a t i s t i c then c r e a t e s a new f i r s t a x i s along the g r e a t e s t e l o n g a t i o n of the c l o u d , thus accounting f o r the maximum v a r i a n c e . The second new a x i s i s pl a c e d through the next g r e a t e s t e l o n g a t i o n p r o v i d e d i t i s orthogonal (at r i g h t angles) to the f i r s t . The t h i r d i s pl a c e d along the next g r e a t e s t e l o n g a t i o n provided i t i s orthogonal to the f i r s t two. In t h i s way each new a x i s i s c r e a t e d so that a new set of axes has been formed. The data p o i n t s are not changed with respect to each other: e f f e c t i v e l y the o r i g i n a l axes have been r o t a t e d and the c e n t r o i d d e s i g n a t e d (0,0). T h i s new s t r u c t u r e now has axes that account f o r maximal v a r i a n c e by the f i r s t axes, .i.e. , each 37 s u c c e s s i v e a x i s accounts f o r l e s s of the system's t o t a l v a r i a n c e . Note that the t o t a l v a r i a n c e has not changed but i s p a r t i t i o n e d d i f f e r e n t l y . A l s o each a x i s i s completely independent of any other, meaning they are completely u n c o r r e l a t e d with each o t h e r . Before one can use t h i s s t a t i s t i c , the nature of the raw data must be examined. I f the v a r i a b l e s are represented by d i f f e r e n t u n i t s of measurement, they should be s t a n d a r d i s e d , u s u a l l y by d i v i d i n g each v a r i a b l e by i t s standard d e v i a t i o n (Pimentel ,1979). T h i s r e s u l t s i n a c o r r e l a t i o n matrix, i . e . , a d i s p e r s i o n of z-s c o r e s . However, i f a l l the v a r i a b l e s share a common u n i t of measurement, as here, one can use the cov a r i a n c e m a t r i x . I t i s c o n v e n t i o n a l to transform using l o g a r i t h m s , t h i s being e s p e c i a l l y a p p r o p r i a t e f o r phytoplankton data as these can range from very low values f o r rare s p e c i e s t o very high v a l u e s f o r bloom organisms. Logarithms of v a r i a b l e s a l s o approximate m u l t i v a r i a t e n o r m a l i t y . The t r a n s f o r m a t i o n used i n t h i s study was l n (biomass + 1). Once the PCA has been executed, a set of new axes and transformed v a r i a b l e s (components) are r e t u r n e d . One can c a l c u l a t e the percent v a r i a n c e accounted f o r by each a x i s and decide how many of the new components one wishes to use i n a n a l y s i n g the system. E i g e n v e c t o r s are composed of elements which are the c o s i n e s between the o r i g i n a l v a r i a b l e s and the PC axes. As the angle approaches 0°, the c o s i n e approaches 1, and the b e t t e r the f i t . Pimentel (1979) s t a t e s that the e i g e n v e c t o r s can be i n t e r p r e t e d 38 with respect to the o r i g i n a l v a r i a b l e s by o b serving the o r i g i n a l v a r i a b l e s ' c o n t r i b u t i n g magnitudes and d i r e c t i o n s . I f a l l the s i g n s are the same the r e s u l t i s a "general component" whereas e i g e n v e c t o r s with mixed sig n s are termed " b i p o l a r components". Goodman et a l . (1984) were able to use e i g e n v e c t o r a n a l y s i s e f f e c t i v e l y , but i n order to be a l i t t l e more robust one should c o r r e l a t e the o r i g i n a l v a r i a b l e s to the transformed v a r i a b l e s ( G i t t i n s , 1985) thereby d e r i v i n g a " c o r r e l a t i o n s t r u c t u r e " which can be t e s t e d f o r s i g n i f i c a n c e . P r i n c i p a l Components A n a l y s i s i s a good way to reduce data by p u t t i n g more infor m a t i o n i n t o fewer v a r i a b l e s . One can use the PCA as an a n a l y t i c t o o l f o r p a t t e r n e x p l o r a t i o n i n i t s e l f , however, as t h i s study had concomitant environmental data, C a n o n i c a l C o r r e l a t i o n A n a l y s i s (CCA) was used to attempt to e x p l a i n phytoplankton d i s t r i b u t i o n s dependent on environmental parameters. The most thorough and i l l u m i n a t i n g account of CCA i s given by G i t t i n s (1985). C a n o n i c a l C o r r e l a t i o n A n a l y s i s b a s i c a l l y f i n d s the maximum c o v a r i a t i o n between two s e t s of v a r i a b l e s . E i t h e r set of v a r i a b l e s can be used to p r e d i c t the other or both s e t s can s i m u l t aneously p r e d i c t each other. In t h i s study, i t i s u n l i k e l y that the b i o l o g i c a l v a r i a b l e s were a f f e c t i n g the environmental ones, t h e r e f o r e t h i s i n t e r a c t i o n was ignored. If the b i o l o g i c a l v a r i a b l e s ( P r i n c i p a l Components) are designated p, and the environmental v a r i a b l e s designated q, there i s some sample s i z e N which i s minimally a c c e p t a b l e . Pimentel (1979) s t a t e s that N should be g r e a t e r than p+q +1 whereas G i t t i n s (1985) p l a c e s 39 N>4x(p+q). A c a n o n i c a l s t r u c t u r e ( e q u i v a l e n t to PCA's c o r r e l a t i o n s t r u c t u r e ) can be formed a f t e r the a n a l y s i s on the s t a n d a r d i s e d data m a t r i c e s . T h i s time there w i l l be two kinds of c o r r e l a t i o n s : 1) i n t r a s e t c o r r e l a t i o n s which r e l a t e the c a n o n i c a l v a r i a t e s and observed v a r i a b l e s of the same domain, and 2) i n t e r s e t c o r r e l a t i o n s which r e l a t e the c a n o n i c a l v a r i a t e s of one domain to the observed v a r i a b l e s of the o t h e r . Whenever a c o r r e l a t i o n i s squared one can get a p r o p o r t i o n of v a r i a n c e e x p l a i n e d . Therefore the squared i n t r a s e t c o r r e l a t i o n i s the p r o p o r t i o n of v a r i a n c e of a given v a r i a b l e e x p l a i n e d by a c a n o n i c a l v a r i a t e of the same domain. A l t e r n a t e l y , the squared i n t e r s e t c o r r e l a t i o n i s the p r o p o r t i o n of v a r i a n c e of a given v a r i a b l e p r e d i c t a b l e by a c a n o n i c a l v a r i a t e of the other domain. F u r t h e r , one can c a l c u l a t e the percent v a r i a n c e e x t r a c t e d by a c a n o n i c a l v a r i a t e which s i g n i f i e s the v a r i a n c e common to both a measurement domain and a p a r t i c u l a r c a n o n i c a l v a r i a t e ( G i t t i n s ,1985). Redundancy i s perhaps the most u s e f u l measure. Redundancy measures the a c t u a l o v e r l a p between s e t s i n c a n o n i c a l space (Pimentel, 1979). A c a n o n i c a l v a r i a t e ' s redundancy i s consequently a u s e f u l index of the p r e d i c t i v e or explanatory power of the c a n o n i c a l v a r i a t e with respect to the other domain ( G i t t i n s ,1985). T o t a l redundancy w i l l t h e r e f o r e g i v e an idea of the v a r i a n c e of one v a r i a b l e set accounted f o r by the other. 40 3.1.2 March, 1986 3.J_.2.J_ N . S t r a i t of Georgia vs Malaspina Complex In t o t a l there were 64 samples (16 s t a t i o n s with 4 depths each) f o r each month, and these w i l l be r e f e r r e d t o as cases. For a meaningful PCA, one should have fewer v a r i a b l e s than cases. T h e r e f o r e , a f t e r an o r i g i n a l grouping of the rare s p e c i e s i n t o t h e i r r e s p e c t i v e genera (e.g., P r o t o p e r i d i n i u m ) , only those " s p e c i e s " which oc c u r r e d i n g r e a t e r than 10% of the cases were used i n the PCA. The c a n o n i c a l s t r u c t u r e i s shown i n Table 2. As s t a t e d e a r l i e r , one can probably assume that the phytoplankton are not a f f e c t i n g the environmental v a r i a b l e s used i n the a n a l y s i s . O r i g i n a l l y there were a l s o v a l u e s f o r sigma-t ( d e n s i t y ) , c h l o r o p h y l l a, and phaeopigments but these were excluded. The l a t t e r two are o b v i o u s l y f u n c t i o n s of the phytoplankton present and c o u l d not r e a l i s t i c a l l y be thought to c o n t r o l the communities. Density i s a f u n c t i o n of temperature and s a l i n i t y and i s t h e r e f o r e a d e r i v e d v a r i a b l e . Pimentel (1979) warns a g a i n s t u s i n g d e r i v e d v a r i a b l e s f o r a v a r i e t y of reasons. A l s o , d e n s i t y changes w i l l more or l e s s be determined by e i t h e r temperature or s a l i n i t y , depending on the regime. In an e s t u a r i n e system such as the southern S t r a i t of Georgia, s a l i n i t y u s u a l l y accounts f o r most of the d e n s i t y f l u c t u a t i o n (LeBlond, 1983). C a n o n i c a l a n a l y s i s normally r e t u r n s two s e t s of v a r i a t e s , each r e l a t e d to the o r i g i n a l domains. Because t h i s study assumes the phytoplankton are not a f f e c t i n g the environment ( a c t u a l l y 41 they do a l t e r c e r t a i n parameters such as n i t r a t e ) only the environmental c a n o n i c a l v a r i a t e s (v) w i l l be used. The f i r s t three c a n o n i c a l v a r i a t e s have been r e t a i n e d (Table 3) and the others d i s c a r d e d as these l a t t e r each account f o r l e s s than 1% of the b i o l o g i c a l domain's v a r i a n c e . The percent v a r i a n c e accounted f o r by the f i r s t p r i n c i p a l component i s 45%, which i s l a r g e f o r a phytoplankton study ( c f . E s t r a d a , 1979; Blasco et a l . , 1980; Goodman et a l . , 1984; Matta & M a r s h a l l , 1984; Kaneta et a l . , 1985; V a l e n t i n et a l . , 1985;). According to B l a c k i t h & Reyment (1971) i t i s usual i n p h y t o s o c i o l o g i c a l s t u d i e s f o r the f i r s t PC a x i s to r e f l e c t abundance. A l l e n & Koonce (1973) found t h e i r f i r s t a x i s to be a biomass st a n d i n g crop a x i s . From the c o r r e l a t i o n s t r u c t u r e i n Table 2, one can see that many s p e c i e s are s i g n i f i c a n t l y (p<=0.0l) c o r r e l a t e d with PC a x i s 1. From t h i s p o i n t on i t i s assumed that s p e c i e s a s s o c i a t e d with any p a r t i c u l a r PC w i l l be s i g n i f i c a n t l y c o r r e l a t e d . Note t h a t the s p e c i e s with h i g h l y p o s i t i v e c o r r e l a t i o n s (r>0.90) — Chaetoceros s o c i a l i s (0.94), Corymbellus aureus (0.96), Detonula pumila (0.98), L e p t o c y l i n d r u s (0.90), and T h a l a s s i o s i r a n o r d e n s k i o e l d i i (0.92) — were a l l extremely abundant i n the Malaspina Complex. Those s p e c i e s with s i g n i f i c a n t n e gative c o r r e l a t i o n s , e s p e c i a l l y cryptomonads (-0.60), u n i d e n t i f i e d thecate d i n o f l a g e l l a t e s (-0.64), m i s c e l l a n e o u s n a n o f l a g e l l a t e s (-0.53), and Micromonas  p u s i l l a (-0.52), are f o r the most p a r t n a n o f l a g e l l a t e s and small d i n o f l a g e l l a t e s which formed the dominant biomass i n the northern S t r a i t of Georgia i n March. 42 PCI i s c o r r e l a t e d with CVI (0.62) which d e s c r i b e s waters of the MC with reduced temperatures and n i t r a t e s , thus c o n f i r m i n g the s p e c i e s o b s e r v a t i o n s made above. N e g a t i v e l y c o r r e l a t e d s p e c i e s of PCI w i l l be l o c a t e d i n the NSG i n areas where temperatures and n i t r a t e s are h i g h e r . A l s o c o r r e l a t e d with PCI i s CVIII (0.36) which d e s c r i b e s higher temperatures and reduced s a l i n i t i e s and n i t r a t e s which d e s c r i b e s the MC i n general r e l a t i v e to the NSG. Increased temperatures are known to i n c r e a s e diatoms' range of l i g h t t o l e r a n c e (Watanabe,1978) so that t h i s f a c t p l u s an i n c r e a s e i n s t r a t i f i c a t i o n due to temperature (hence a b e t t e r l i g h t regime) would favour diatom growth. I t was found that PC's II and III were q u i t e u s e f u l i n d e s c r i b i n g s p e c i e s d i s t r i b u t i o n s with l o c a t i o n and depth. T h e r e f o r e , F i g u r e 3 p r e s e n t s the s p e c i e s c o r r e l a t i o n s with these two components which are c h a r a c t e r i s e d as f o l l o w s . PCII i s r e l a t e d to both CVI (-0.47) and CVII (-0.58), the former d e s c r i b i n g l o c a t i o n as above and the l a t t e r d e s c r i b i n g depth. N e g a t i v e l y c o r r e l a t e d s p e c i e s with PCII such as E u t r e p t i e l l a (-0.76), A p e d i n e l l a s p i n i f e r a (-0.65), c i l i a t e s (-63.), and T e t r a s e l m i s (-0.59) are t h e r e f o r e more abundant in the s u r f a c e waters of the MC and northern s e c t i o n of the NSG. D i c r a t e r i a (0.33) i s the only s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n so we are l e f t to assume t h i s s p e c i e s i s found more at depth i n the NSG. I t i s i n t e r e s t i n g to note that a l l s p e c i e s showing s i g n i f i c a n t c o r r e l a t i o n s with PCII are m o t i l e . PCIII i s p o s i t i v e l y c o r r e l a t e d with CVI (0.52) and 43 n e g a t i v e l y with CVII (-0.45), t h e r e f o r e , s p e c i e s p o s i t i v e l y a s s o c i a t e d with PCIII w i l l be more abundant i n the MC and northern NSG's deeper waters. Such organisms are c h o a n o f l a g e l l a t e s (0.53), z o o f l a g e l l a t e s (0.42), P r o t o p e r i d i n i u m (0.36), and E u t r e p t i e l l a (0.35). Most s i g n i f i c a n t s p e c i e s c o r r e l a t i o n s , however, are negative so that they are found more in NSG's s u r f a c e waters. Some of the more h i g h l y c o r r e l a t e d organisms are mi s c e l l a n e o u s n a n o f l a g e l l a t e s (-0.55), Th. a e s t i v a l i s (-0.51), Chrysochromulina (-0.49), Mesodinium  rubrum (-0.49), and C y l i n d r o t h e c a (-0.47). PCIV i s mostly a f f e c t e d by CVIII (-0.26) and thus d e s c r i b e s c o l d e r temperatures with higher s a l i n i t i e s and n i t r a t e s . Ch. convolutus (0.49) has been d e s c r i b e d as a c o l d water s p e c i e s ( r e f ) while M. rubrum (0.41) p r e f e r s c o n d i t i o n s of up w e l l i n g where temperatures are presumably c o o l e r (Bary,l953; Fonds & Eisma,l967; Ryther,1967). Most c o r r e l a t e d with c o l d e r temperatures i s the prasinophyte Pyramimonas (0.65) while gymnodinoids (-0.37) and T e t r a s e l m i s (-0.45) are o c c u r r i n g i n the warmer waters. PCV i s l e a s t e x p l a i n e d by the r e t a i n e d c a n o n i c a l v a r i a t e s . There i s a weak c o r r e l a t i o n with CVII (0.14) which i s h i g h l y s u r f a c e o r i e n t e d with reduced s a l i n i t y and n i t r a t e . Gyrodinium (0.48) and Cos e i n o d i s c u s (0.36) are p o s i t i v e l y r e l a t e d to the su r f a c e waters. T h i s diatom i s u s u a l l y a r a t h e r heavy organism so that there may be a c e r t a i n amount of turbulence i n v o l v e d which would keep C o s c i n o d i s c u s suspended i n the upper l a y e r s . Grontved (1952) found oleaginous s u r f a c e patches of 44 C o s c i n o d i s c u s coneinnus i n the North Sea d u r i n g a p e r i o d of thermal s t r a t i f i c a t i o n . Because v e r t i c a l a d v e c tion was probably minimal, he a t t r i b u t e d the diatom's buoyancy to i n c r e a s e d o i l c o n t e n t . Responding n e g a t i v e l y to CVII, and thus i n d i c a t i n g a p r e f e r e n c e f o r deeper waters, are Th. a e s t i v a l i s (-0.48) and T h a l a s s i o t h r i x f r a u e n f e l d i i (-0.32). The above a n a l y s i s has p i c k e d out a few t r e n d s . Most of the v a r i a n c e i s l o c a t i o n - and d e p t h - r e l a t e d . There were two very d i f f e r e n t communities i n March, c o n s i s t i n g of s u r f a c e - o r i e n t e d n a n o f l a g e l l a t e s i n the NSG and diatoms i n the MC. The l a t t e r organisms comprised the m a j o r i t y of the biomass. The redundancy val u e s f o r the CV's i n d i c a t e l i t t l e of the v a r i a t i o n i n the phytoplankton domain i s being e x p l a i n e d by elements of the environmental domain. In f a c t , i f one removes the redundancies due to l o c a t i o n and depth, one sees that roughly 2% of the v a r i a n c e of the b i o l o g i c a l v a r i a b l e s i s e x p l a i n e d by temperature a l o n e . S a l i n i t y and n i t r a t e are of l i t t l e consequence at t h i s time of year, other than the former's c o n t r i b u t i o n to s t r a t i f i c a t i o n . 45 TABLE 2 Species Corre la t ions with P r i n c i p a l Components N .Str .Georg ia and Malaspina, March,1986 Code Species PCI PCI I PCI 11 PCIV PCV 1 Amph i d 0.16 0.00 0.16 - 0 . 0 2 0.15 2 Apedin 0 . 1 0 -0.65* 0.11 -0.22 - 0 . 2 1 3 C e r a t i 0.85* -0.24 -0.09 0.00 - 0 . 1 0 4 Chacnv 0.31 -0.06 0.21 0.49* 0.23 5 Chadeb 0 . 8 6 * -0.04 -0.07 -0.05 0.19 6 Chadec 0.81* 0 . 0 2 0.08 - 0 . 0 2 -0.05 7 Chaeto 0.80* -0.03 -0.23 0.04 0.06 8 Chasoc 0.94* -0.06 0 . 1 0 -0.09 -0.07 9 Choano 0.06 -0.49* 0.53* 0.27 0.04 10 Chryso -0.34* 0.08 -0.49* 0 . 0 2 0.00 1 1 C i l i a t -0.32* -0.63* -0.35* 0.04 0 . 2 0 12 C o r c r i -0.13 -0.27 0 . 1 2 -0.22 0.29 13 Corymb 0.96* 0 . 0 2 - 0 . 0 1 0.00 0.06 1 4 Cose in 0.83* 0.13 0 . 1 0 - 0 . 0 1 0.36 1 5 Crypto -0.60* -0.47* - 0 . 2 0 0.03 0.25 16 C y l i n d 0.69* 0.22 -0.47* 0 . 0 2 0 . 0 1 17 Detpum 0.98* -0.05 0.08 -0.05 -0.07 18 Dicrat -0.08 0.33* -0.44* - 0 . 0 1 0.05 19 Dicspe 0.39* -0.44* -0.34* 0.07 0 . 0 2 2 0 Diplop 0.67* 0.04 -0.14 -0.05 -0.28 21 D i t b r i 0.44* 0.09 0.07 0.05 0.11 22 Euczoo 0.69* -0.09 - 0 . 0 1 0.18 0.13 23 Eutrep -0.03 -0.76* 0.35* -0.14 - 0 . 1 8 24 Glenod -0.64* -0.32* -0.38* -0.17 0 . 0 2 25 Gonyau 0.62* - 0 . 1 0 - 0 . 0 1 0.17 - 0 . 1 2 * S ign i f i cant at the 2.5% c r i t i c a l l e v e l 46 TABLE 2 (Cont'd) Species Corre la t ions with P r i n c i p a l Components N .Str .Georg ia and Malaspina, March,1986 Code Spec ies PCI PCII PCI 11 PCIV PCV 26 Gymnod -0.35* -0.24 0.09 -0.37* 0.14 27 Gyrodi -0.25 -0.38* -0.03 0.32* 0.48* 28 Katodi -0.13 0.11 -0.33* -0.17 -0.13 29 Leptoc 0.90* 0.08 0.14 -0.01 -0.09 30 Licmop -0.18 0.31 -0.21 0.08 -0.05 31 Mesrub 0.19 -0.46* -0.49* 0.41* 0.28 32 Microf -0.53* 0.20 -0.55* 0.17 -0.11 33 Microm -0.52* -0.16 -0.35* -0.08 0.07 34 Navicu 0.60* -0.10 0.10 -0.19 0.11 35 Nitzsc 0.60* 0.02 -0.22 -0.10 0.02 36 Pennat 0.58* 0.20 -0.46* - 0 . 18 -0.07 37 Pleuro 0.29 0.08 -0.13 -0.10 0.21 38 Protop 0.51* -0.35* 0.36* -0.02 0.09 39 Pyrami -0.43* -0.23 0.01 0.65* 0.02 40 Rhifra 0.53* 0.05 0.06 0.10 0.09 41 Scripp 0.82* -0.21 -0.06 0.08 -0.17 42 Skecos 0.27 -0.24 -0.41* 0.22 0.22 43 Stenip 0.83* 0.08 0.04 -0.17 0.09 44 Tetras -0.34* -0.59* -0.25 -0.45* 0.27 45 Thaaes 0.50* -0.18 -0.51* 0.06 -0.48* 46 Thaags 0.73* 0.17 0.13 0.19 0.20 47 Thaang 0.58* -0.09 -0.21 -0.17 0.24 48 Thaecc 0.82* 0. 12 -0.11 -0.15 0.08 49 Thafra 0.40* -0.24 0.01 -0.01 -0.32* 50 Thanit 0.46* 0.24 -0.10 -0.23 0.11 51 Thanor 0.92* 0.08 -0.01 -0.00 0.10 52 Tharot 0.71* 0.04 -0.33* 0.20 0.18 53 Zoofla 0.44* -0.26 0.42* 0.27 -0.27 * S i g n i f i c a n t at the 2.5% c r i t i c a l l eve l 47 TABLE 3 Corre la t ions with Canonical Variates N . S t r . Georgia and Malaspina Complex March 18-19 Canonical Var ia te v1 v2 v3 Comm C o r r e l . C o e f f . ( R ) 0. .42 0. 34 0. .25 R-squared 0, .18 0. 1 2 0. .06 Environment Location 0. .95 -0 . 08 0. .09 0. 91 Depth -0. .09 - o . 98 -0. .08 0. 98 Temperature -0. .32 0. 1 1 0. .76 0. 69 S a l i n i t y -0. .07 - o . 35 -0. .29 0. 21 Ni tra te -0, .55 - o . 30 -0. .25 0. 45 Variance extracted 0, .26 . 0. 24 0. .15 0. 65 Phytoplankton Pr in Comp I 0. .62 - o . 05 0. .36 0. 51 Pr in Comp II -0. .47 - o . 58 0. . 1 5 0. 58 Pr in Comp III 0. .52 -0 . 45 -0. .29 0. 56 Pr in Comp IV -0. .01 0. 16 -0. .26 0. 09 Pr in Comp V -0. .03 0. 1 4 0. , 1 1 0. 03 Redundancy 0, .16 0. 07 0. .02 0. 25 48 F i g u r e 3. Species C o r r e l a t i o n s w i t h PC's I I S I I I NSG vs MC, March 18-19, 1986. Environmental c o r r e l a t i o n s w i t h each component are d e f i n e d . + 've - NSG. Deep -*ve - MC, Surface C o r r e l a t i o n w i t h PCII 49 3_.J_.2.2 Northern S t r a i t of Georgia The northern S t r a i t of Georgia (NSG) i n March was dominated by c i l i a t e s (33% of biomass), Gyrodinium (20%), cryptomonads (15%), and Chrysochromulina (14%), the l a t t e r two being the p h o t o s y n t h e t i c dominants. In an attempt to r e s o l v e t h i s r e gion's ecology without the i n t e r f e r e n c e of the o b v i o u s l y d i f f e r e n t Malaspina Complex, a CCA was performed s p e c i f i c to the NSG. Before running the PCA f o r data r e d u c t i o n , the number of s p e c i e s had to be reduced below the number of cases (48). Only those s p e c i e s o c c u r r i n g i n at l e a s t 10% of the samples were used so that the new set of v a r i a b l e s numbered 42 i n s t e a d of 58. These phytoplankton v a r i a b l e s were c o l l a p s e d i n t o 5 p r i n c i p a l components c o n t a i n i n g 55% of the o r i g i n a l i n f o r m a t i o n and used as the b i o l o g i c a l domain. The environmental domain c o n s i s t e d of t r a n s e c t number, running from 1 f o r the southernmost t r a n s e c t to 5 f o r the northernmost; s t a t i o n , 1 f o r the westernmost s t a t i o n w i t h i n a t r a n s e c t , 3 f o r the middle s t a t i o n , and 5 f o r the easternmost s t a t i o n ; depth of the sample; temperature; s a l i n i t y ; and n i t r a t e . The PCA's c o r r e l a t i o n s t r u c t u r e i s presented i n Table 4 and the CCA's c a n o n i c a l s t r u c t u r e i n Table 5. The f i r s t t hree c a n o n i c a l v a r i a t e s have been r e t a i n e d , accounting f o r 16.2%, 10.8%, and 5.7% of the b i o l o g i c a l domain's v a r i a n c e , r e s p e c t i v e l y . F i g u r e 4 p r e s e n t s the s p e c i e s c o r r e l a t i o n s with depth and l o c a t i o n . PCI i s i n f l u e n c e d g r e a t l y by CVI (0.93) which i s g e o g r a p h i c a l i n nature. In going from south to north and from west to e a s t , the temperature decreases as does the n i t r a t e . 50 Presumably, S t a t i o n 1a (near Comox) has the h i g h e s t temperatures and n i t r a t e s and S t a t i o n 5e the lowest. R e a l i s t i c a l l y , the anomalous Stn 1a i s probably dominating the v a r i a n c e . Species i n c r e a s i n g along t h i s d i a g o n a l l o c a t i o n v e c t o r are c h o a n o f l a g e l l a t e s (0.80), E u t r e p t i e l l a (0.79), P r o t o p e r i d i n i u m (0.55), A. s p i n i f e r a (0.53), z o o f l a g e l l a t e s (0.52), and Gyrodinium (0.45). Those organisms de c r e a s i n g i n t h i s g eneral d i r e c t i o n and t h e r e f o r e responding favourably to Stn l a ' s warmer temperatures are C y l i n d r o t h e c a (-0.75), pennate diatoms (-0.66), D i c r a t e r i a (-0.61), m i s c e l l a n e o u s n a n o f l a g e l l a t e s (-0.60), Th. e c c e n t r i c a (-0.52), Chrysochromulina (-0.49), and Th. r o t u l a (-0.44). PCII i s n e g a t i v e l y c o r r e l a t e d with CVII (-0.80), a strong depth v a r i a t e which i s c h a r a c t e r i s e d by a s a l i n i t y change. Species p o s i t i v e l y c o r r e l a t e d with PCII are t h e r e f o r e s t r o n g l y s u r f a c e s t r a t i f i e d where s a l i n i t i e s are reduced. These organisms are c i l i a t e s (0.75), M . rubrum (0.73), D i c t y o c h a speculum (0.62), Gyrodinium (0.61), u n i d e n t i f i e d thecate d i n o f l a g e l l a t e s (0.60), and cryptomonads (0.54). The only organism f a v o u r i n g deeper waters i s L e p t o c y l i n d r u s (-0.45), probably the s m a l l e r minimus. L i g h t l e v e l s must be very low i n deeper waters at t h i s time of year and organisms tend to be s m a l l , and t h e i r p l a s t i d s occupy a r e l a t i v e l y l a r g e r percent of t h e i r t o t a l volume. By maximising t h i s , a c e l l experiences g r e a t e r i r r a d i a n c e per volume (Taguchi, 1976). PCIII i s p o s i t i v e l y c o r r e l a t e d with CVIII (0.63) which i s another g e o g r a p h i c a l v a r i a t e . T h i s time as one heads north and 51 west, the temperature shows a s l i g h t i n c r e a s e , a trend o c c u r r i n g o u t s i d e the dominance of Stn l a ' s h i g h temperatures. I n c r e a s i n g along t h i s NW d i a g o n a l v e c t o r are T e t r a s e l m i s (0.63), Thalassionema n i t z s c h i o i d e s (0.61), Th. a n g u s t e - l i n e a t a (0.41), and Pleurosigma (0.41). I n c r e a s i n g i n a s o u t h e a s t e r l y d i r e c t i o n are Pyramimonas (-0.65), Ch. convolutus (-0.45), and m i s c e l l a n e o u s n a n o f l a g e l l a t e s (-0.37). I t i s i n t e r e s t i n g to note the s e p a r a t i o n of the two prasinophyte genera, T e t r a s e l m i s and Pyramimonas. Perhaps e c o l o g i c a l s e p a r a t i o n of these p r a s i n o p h y t e s depends on temperature. PCIV i s not e x p l a i n e d by any of the three v a r i a t e s . P o s i t i v e c o r r e l a t i o n s with PCIV are shown by Th. a e s t i v a l i s (0.66) and z o o f l a g e l l a t e s (0.54) while cryptomonads (-0.45), Ch. d e b i l i s (-0.42), and Corethron c r i o p h i l u m (-0.41) are n e g a t i v e l y c o r r e l a t e d . PCV i s p o s i t i v e l y c o r r e l a t e d with the NW-SE c r o s s - s t r a i t v a r i a t e CVIII (0.37) which would probably be near s t a t i o n 5a ( c l o s e s t t o D i s c o v e r y Passage's t i d a l j e t ) . A l s o a f f e c t i n g PCV i s the depth v a r i a t e CVII (0.19) so that the s p e c i e s i n t h i s area may tend towards depth. P o s i t i v e s p e c i e s c o r r e l a t i o n s are P r o t o p e r i d i n i u m (0.56), Th. a n g u s t e - l i n e a t a (0.42), Amphidinium (0.42), and Th. n o r d e n s k i o e l d i i (0.38). Perhaps P r o t o p e r i d i n i u m s p e c i e s are g r a z i n g the two T h a l a s s i o s i r a s p e c i e s i n t h i s a r e a . Contrary to PCIII, where T e t r a s e l m i s and Th. a n g u s t e - l i n e a t a are c o - o c c u r r i n g , here the prasinophyte has a n e g a t i v e c o r r e l a t i o n with PCV. T e t r a s e l m i s may be o c c u r r i n g i n the same region but i s removed depthwise, p r e f e r r i n g the s u r f a c e waters. 5 2 The p a t t e r n emerging from t h i s a n a l y s i s i s one where s p e c i e s were changing i n a d i a g o n a l c r o s s - s t r a i t f a s h i o n due mostly to temperature d i f f e r e n c e s . In the NE corner, c h o a n o f l a g e l l a t e s , E u t r e p t i e l l a , P r o t o p e r i d i n i u m , A. s p i n i f e r a , and Gyrodinium became more numerous. The SW was more favourable to C y l i n d r o t h e c a , D i c r a t e r i a , Chrysochromulina, T h a l a s i o s i r a  e c c e n t r i c a , and Th. r o t u l a . In the NW T e t r a s e l m i s , Thalassionema  n i t z s c h i o i d e s , Th. a n g u s t e - l i n e a t a , and Pleurosiqma i n c r e a s e d while i n the SE Pyramimonas and Chaetoceros convolutus were more abundant than elsewhere. S a l i n i t y d i f f e r e n c e s were causing a v e r t i c a l s p e c i e s s e p a r a t i o n which i n v o l v e d the high biomass s p e c i e s , a l l found c l o s e r to the s u r f a c e . Deep water communities were depauperate at t h i s time of year due to the l i g h t l i m i t a t i o n . L e p t o c y l i n d r u s minimus seemed to be well-adapted to the low l i g h t l e v e l s at depth. 53 TABLE 4 Species C o r r e l a t i o n s with P r i n c i p a l Components Northern S t r a i t of Georgia, March,1986 Code Species PCI PCII PCI 11 PCIV PCV 1 Amphid 0.10 -0. 17 0.14 -0.27 0.42* 2 Apedin 0.53* 0.17 0.07 0.02 -0.11 3 Chacnv 0.31 0.28 -0.45* -0.13 -0.15 4 Chadeb -0.25 0.31 0.08 -0.42* -0.03 5 Chaeto -0.38* 0.50* -0.03 0.07 -0.02 6 Choano 0.80* -0.02 -0.18 -0.10 -0.07 7 Chryso -0.49* 0.20 -0.04 -0.02 0.16 8 C i l i a t 0.22 0.75* 0.18 -0.09 -0.17 9 C o r c r i 0.30 0.07 0.06 -0.41* -0.32 10 Crypto 0.31 0.54* 0.08 -0.45* 0.01 1 1 C y l i n d -0.75* 0.24 0.00 0.06 -0.07 12 D i c r a t -0.61* -0.10 -0.09 -0.23 -0.00 13 Dicspe -0.02 0.62* 0.17 0.26 0.12 14 D i p l o p -0.32 -0.29 0.14 0.16 -0.07 15 D i t b r i -0.07 0.08 0.10 0.21 0.11 16 Eutrep 0.79* 0. 16 0.38* 0.26 0.07 17 Glenod -0.19 0.60* 0.28 -0.04 0.07 18 Gymnod 0.25 0.03 0.38* 0.15 -0.19 19 Gyrodi 0.45* 0.61* -0.02 -0.05 -0.08 20 Katodi -0.37* -0.04 0.02 0.24 -0.29 21 Leptoc -0.07 -0.45* -0.08 0.08 0.17 22 Licmop -0.37* -0.09 -0.18 0.07 0. 16 23 Mesrub -0.03 0.73* -0.14 -0.23 0.28 24 M i c r o f -0.60* 0.18 -0.37* 0.06 -0.32 25 Microm -0.19 0.21 0.05 -0.21 -0.18 26 Navicu 0.02 -0.00 0.07 -0.12 -0.09 27 N i t z s c -0.31 0. 14 0.14 -0.05 -0. 13 28 Pennat -0.66* 0.18 0.15 0.18 -0.27 29 Pl e u r o -0.24 0.04 0.41* 0.14 0.19 30 Protop 0.55* 0.05 0.34 -0.03 0.56* 31 Pyrami 0.31 0.46* -0.65* -0.00 -0.11 32 Skecos -0.14 0.67* -0.14 -0.11 -0.19 33 S t e n i p -0.21 -0.13 0.37* 0.01 -0.07 34 T e t r a s 0.20 0.46* 0.63* -0.17 -0.42* 35 Thaaes -0.39* 0.34 0.08 0.66* -0.07 36 Thaang -0.25 0. 17 0.41 0.01 0.42* 37 Thaecc -0.52* 0.16 0.31 0.03 0.20 38 Th a f r a 0.23 0.05 -0.06 0.20 -0.04 39 Th a n i t -0.36 0.01 0.61* 0.22 0.23 40 Thanor -0.36 0.25 0.03 -0.23 0.38* 41 Tharot -0.44* 0.50* -0.19 -0.09 0.35 42 Z o o f l a 0.52* 0.07 -0.28 0.54* 0.11 * S i g n i f i c a n t at the 2.5% c r i t i c a l l e v e l 54 TABLE 5 Correlations with Canonical Variates Northern S t r a i t of Georgia March 18-19 Canonical Variate v1 v2 v3 Comm Correl.COeff.(R) 0. 42 0. 38 0. 33 R-squared 0. 18 0. 15 0. 1 1 Environment Transect 0. 75 -0. 13 0. 58 0.94 Station 0. 63 0. 1 1 -o. 68 0.96 Depth 0. 06 0. 97 0. 10 0.99 Temperature -0. 55 -0. 05 0. 33 0.67 S a l i n i t y 0. 13 0. 31 0. 18 0.59 Nitrate -0. 31 0. 20 0. 16 0.66 Variance extracted 0. 20 0. 16 0. 14 0.50 Phytoplankton Prin Comp I 0. 93 -0. 15 0. 04 0.89 Prin Comp II -0. 16 -0. 80 -o. 06 0.68 Prin Comp III -0. 07 -0. 17 0. 63 0.45 Prin Comp IV 0. 06 0. 02 0. 02 0.08 Prin Comp V 0. 00 0. 19 0. 37 0.23 Redundancy 0. 1 6 0. 1 1 0. 06 0.33 55 F i g u r e 4 . Species C o r r e l a t i o n s w i t h PC's I I S I I I N.Str.Georgia, March 18-19. 1986. Environmental c o r r e l a t i o n s w i t h each component are d e f i n e d . M M M o Q_ x: 4J O d io o O nt o +'va - Surface, Less saline -'ve - Deep, More saline * o C o o ft 4J (0 CU 2 ? C o a o I 10 o I Tetraa Cll lat Leptoc ?^ ~——————•=»==:=— Byrodl V. ****.."*•"••—Chaeto V ^-T " " ^ ^ Ske^oa Mearub Micro f \ Chacnv c. c a a e i-i c o a o x u 4J 4J n a as a x o C JC 4J *> C 3 o o Z CO Tharot o - 0 . 6 \ \ \ \ pyraml J. o to > > - 0 . 4 - 0 . 2 0.0 0.2 0.4 C o r r e l a t i o n w i t h PCII 0.6 56 3.K3 A p r i 1, 1986 3_._KJ3.J_ N . S t r a i t of Georgia vs Malaspina Complex The phytoplankton data f o r A p r i l , 1986, were reduced as d e s c r i b e d e a r l i e r down to 5 p r i n c i p a l components c o n t a i n i n g 70% of the t o t a l v a r i a n c e (Table 6). These components were then used i n the c a n o n i c a l c o r r e l a t i o n a n a l y s i s with the environmental v a r i a b l e s : l o c a t i o n , depth, temperature, s a l i n i t y , and n i t r a t e . The r e s u l t s are presented i n Table 7 as a c a n o n i c a l s t r u c t u r e . Only the f i r s t two c a n o n i c a l v a r i a t e s c o n t r i b u t e meaningful i n f o r m a t i o n to the c a n o n i c a l model, having redundancies of 13.2% and 6.0%, r e s p e c t i v e l y . Together they e x t r a c t 57.7% of the environmental v a r i a n c e . F i g u r e 5 p r e s e n t s the s p e c i e s c o r r e l a t i o n s with depth and l o c a t i o n . From CVI one can see that l o c a t i o n (0.77) i s a determinant of PCI as w e l l as reduced s a l i n i t i e s (-0.74) and n i t r a t e s (-0.62). T h i s means that a l l the p o s i t i v e s p e c i e s c o r r e l a t i o n s with PCI are dominant phytoplankton i n the MC. The most h i g h l y c o r r e l a t e d s p e c i e s are O d o n t e l l a l o n g i c r u r i s (0.92), Chaetoceros  e i b e n i i (0.98), Ch. s o c i a l i s (0.94), C y l i n d r o t h e c a (0.94), Eucampia zoodiacus (0.98), N i t z s c h i a p a c i f i c a (0.93), N o c t i l u c a  s c i n t i l l a n s (0.97), R h i z o s o l e n i a d e l i c a t u l a (0.98), and R. s e t i q e r a (0.98). The MC has maintained i t s diatom c h a r a c t e r , however, the s p e c i e s have s h i f t e d to those more c h a r a c t e r i s t i c of a l a t e r stage i n s u c c e s s i o n , i n d i c a t e d by Chaetoceros and R h i z o s o l e n i a spp. (Margalef, 1958; Margalef, 1962; H a r r i s o n et a l . , 1983). A l s o n o t i c e the s i g n i f i c a n t c o n t r i b u t i o n s by N. s c i n t i l l a n s , a phagotroph, and P r o t o p e r i d i n i u m , a diatom 57 grazer (Gaines & T a y l o r , 1984; Jacobson & Anderson,1986). The negative c o r r e l a t i o n s c h a r a c t e r i s i n g PCI are s p e c i e s a s s o c i a t e d with the NSG: Ch. convolutus (-0.91), Corethron c r i o p h i l u m (-0.94), Skeletonema costatum (-0.53), T h a l a s s i o s i r a a e s t i v a l i s (-0.57), Th. e c c e n t r i c a (-0.56), and Th. n o r d e n s k i o e l d i i (-0.54). N o t i c e how the NSG has more of a diatom community than i n March. A l l the g r e a t e s t negative c o r r e l a t i o n s are with diatoms which are not biomass dominants in A p r i l . T h i s group t h e r e f o r e seems to p r e f e r higher s a l i n i t y waters of the NSG, and as there i s no depth s p e c i f i c i t y one can assume the more s a l i n e waters of the S t r a i t ' s west Side are i n d i c a t e d . PCII i s c h a r a c t e r i s e d by m o t i l e forms (except Th. r o t u l a (0.63)) which i n c l u d e u n i d e n t i f i e d thecate d i n o f l a g e l l a t e s (0.78), A. s p i n i f e r a (0.71), a " f u z z y " c i l i a t e (0.63), Mesodinium rubrum (0.62), E u t r e p t i e l l a (0.57), and S c r i p p s i e l l a  t r o c h o i d e a (0.53). A l l s i g n i f i c a n t c o r r e l a t i o n s are p o s i t i v e f o r t h i s component which i s mostly a f f e c t e d by CVII (0.29). T h i s v a r i a t e i s a warm temperature, low s a l i n i t y one found roughly i n the upper l a y e r s of the NSG's water column. An i n s p e c t i o n of s a l i n i t y p r o f i l e s suggests that CVII i s even more s p e c i f i c i n that i t c h a r a c t e r i s e s the e a s t e r n NSG where s a l i n i t i e s are n o t i c e a b l y l e s s at the s u r f a c e than those on the western s i d e . O v e r a l l , however, s t r a t i f i c a t i o n i s being h i g h l i g h t e d and the s p e c i e s of PCII are found i n the upper l a y e r s of these waters. PCIII i s a f f e c t e d by CVII (-0.63) but i n a negative way. T h e r e f o r e , the upper waters of the e a s t e r n NSG with warmer temperatures and reduced s a l i n i t i e s i s a good environment f o r 58 c i l i a t e s (-0.31), D i c r a t e r i a (-0.43), and T e t r a s e l m i s (-0.53). Conversely, the deeper waters of the MC are c h a r a c t e r i s e d by C. d e b i l i s (0.39), Th. a e s t i v a l i s (0.32), Th. e c c e n t r i c a (0.46), and Th. n o r d e n s k i o e l d i i (0.52). PCIV i s not e x p l a i n e d by e i t h e r c a n o n i c a l v a r i a t e very w e l l . N e v e r t h e l e s s , i t i s mostly a f f e c t e d by CVII (-0.13), here denoting the MC's deeper waters. The s p e c i e s responding p o s i t i v e l y are Th. a e s t i v a l i s (0.46), R. f r a g i l i s s i m a (0.40), Thalassionema n i t z s c h i o i d e s (0.39), Ch. c o n s t r i c t u s (0.34), Ch. d e b i l i s (0.34), and S c r i p p s i e l l a (0.33). Those s p e c i e s showing an opposite response are Micromonas p u s i l l a (-0.47), M. rubrum (-0.45), E u t r e p t i e l l a (-0.35), and Amphidinium (-0.34). I n t e r p r e t a t i o n i s d i f f i c u l t and s i g n i f i c a n c e probably low. In g e n e r a l , there i s a s e p a r a t i o n of diatoms and f l a g e l l a t e s based p a r t l y on depth and p a r t l y on l o c a t i o n . PCV i s n e g a t i v e l y a f f e c t e d by the l o c a t i o n v a r i a t e CVI (-0.25). I t s d i r e c t i o n p l a c e s i t somewhere i n the NSG where s a l i n i t i e s are higher and n i t r a t e r e p l e t e . N e g a t i v e l y a f f e c t i n g PCV i s a l s o CVII (-0.20) which d e s c r i b e s deeper, c o o l e r , more s a l i n e waters of the MC. Responding p o s i t i v e l y to the above regimes are Th. r o t u l a (0.56), Licmophora (0.46), Detonula  pumila (0.45), T h a l a s s i o t h r i x f r a u e n f e l d i i (0.37), and T. n i t z s c h i o i d e s (0.33). The only n e g a t i v e l y a s s o c i a t e d s p e c i e s i s the " f u z z y " c i l i a t e (-0.52) which would appear to be found i n s u r f a c e waters that are warmer and l e s s s a l i n e . In f a c t , t h i s c i l i a t e was h i g h l y abundant i n s u r f a c e waters of Stn 1e. Redundancy values f o r the v a r i a t e s show that l o c a t i o n i s 59 the b i g g e s t source of e x p l a i n e d v a r i a n c e and i s the major d i s c r i m i n a t o r of PCI. Depth i s s t i l l of secondary importance and we see that NSG's upper waters are q u i t e d i s t i n g u i s h e d s p e c i e s - w i s e , having a range of m o t i l e forms. I n t e r e s t i n g l y , s t r a t i f i c a t i o n i n the NSG i s brought f o r t h as a t e m p e r a t u r e - s a l i n i t y phenomenon while the MC i s c h a r a c t e r i s e d by lower s a l i n i t i e s and n i t r a t e s without s t r a t i f i c a t i o n being of major importance to s p e c i e s d i f f e r e n c e s . 60 TABLE 6 Species Corre la t ions with P r i n c i p a l Components N .Str .Georg ia and Malaspina, Apr i l ,1986 Code Species PCI PCII PCI 11 PCIV PCV 1 Actund 0.86* -0.02 0.09 -0.12 0.18 2 Amphid 0.33 -0.02 -0.10 -0.34* 0.16 3 Apedin -0.22 0.71* -0.26 0.03 -0.14 4 Balloo -0.27 0.11 -0.14 0.09 0.01 5 Bidlon 0.92* 0.06 -0.06 0.10 -0.10 6 Chacnv -0.91* 0.04 0.07 -0.17 -0.08 7 Chacst 0.67* -0.11 -0.26 0.34* -0.18 8 Chadeb 0.61* 0.24 0.39* 0.34* 0.07 9 Chadec 0.89* 0.05 0.11 0.02 -0.12 10 Chaeib 0.98* -0.02 -0.01 -0.02 0.05 1 1 Chaeto 0.49* 0.22 0.32* 0.32* -0.06 12 Chasoc 0.94* 0.10 -0.01 0.00 0.07 13 Choano 0.28 -0.10 -0.09 -0.17 0.19 14 Chryso -0.32* 0.04 -0.00 -0.25 0.19 1 5 C i l i a t -0.48* 0.37* -0.31 -0.16 -0.07 16 Corcr i -0.93* 0.07 0.06 -0.12 0.01 17 Coscin 0.83* -0.25 -0.01 0.07 0.15 18 Crypto -0.40* 0.46* -0.19 -0.32* -0.02 19 Cy l ind 0.94* 0.01 -0.02 -0.01 0.14 20 Detpum -0.21 0.23 0.10 0.19 0.45* 21 Dicrat -0.18 0.27 -0.43* -0.22 0.20 22 Dicspe 0.47* 0.40* 0.12 0.22 -0.13 23 Diplop 0.64* 0.44* -0.18 0 . 1 9 -0.10 24 Dispse 0.83* 0.15 -0.02 0.05 -0.02 25 D i t b r i -0.07 0.21 0.17 0.09 -0.00 26 Ebr ia - 0 . 1 9 0.11 0.24 0.38* -0.13 27 Euczoo 0.98* 0.02 0.02 -0.02 0.05 28 Eutrep -0.02 0.57* -0.15 -0.35* -0.03 29 Fuzzba 0.12 0.63* 0.19 0.06 -0.52* 30 Glenod 0.14 0.78* -0.08 -0.03 -0.13 * S ign i f i cant at the 2.5% c r i t i c a l l e v e l 61 TABLE 6 (Cont'd) Species Corre la t ions with P r i n c i p a l Components N.Str .Georg ia and Malaspina, Apri l ,1986 Code Species PCI PCII PCI 11 PCIV PCV 31 Gonyau 0.79* 0 . 1 8 0.17 -0.20 0.09 32 Gymnod 0.43* 0.28 -0.03 -0.16 0.20 33 Gyrodi -0.15 0.13 -0.15 0.16 0.28 34 Leptoc 0.51* 0.26 0.22 0.20 0.10 35 Licmop -0.13 0.09 0.11 -0.19 0.46* 36 Mesrub -0.04 0.62* 0.15 -0.45* 0.04 37 Microm -0.36* 0.19 -0.20 -0.47* 0.11 38 Navicu 0.71* 0.25 -0.03 0.08 -0.09 39 Nitpac 0.93* -0.06 0.10 -0.11 -0.00 40 Nitzsc 0.36* -0.04 0.09 0.27 0.12 41 Nocsc i 0.97* -0.03 -0.02 0.03 0.09 42 Pennat 0.43* -0.08 -0.27 -0.03 -0.05 43 Pleuro 0.78* 0.11 0.15 0.11 0.09 44 Protop 0.45* 0.20 -0.23 0.06 0.08 45 Rhidel 0.98* 0.00 0.02 -0.02 0.02 46 Rhi fra -0.19 0.29 0.13 0.40* 0.17 47 Rhiset 0.97* 0.05 0.00 -0.05 0.00 48 Scripp 0.19 0.53* -0.14 0.33* -0.01 49 Skecos -0.53* -0.10 0.02 0.18 0.08 50 Stenip -0.27 0.08 0.22 0.19 -0.14 51 Tetras -0.23 0.43* -0.53* 0.14 0.01 52 Thaaes -0.57* 0.14 0.32* 0.46* 0.19 53 Thaecc -0.56* 0.17 0.46* -0.21 -0.07 54 Thafra 0.05 0.36* -0.03 -0.03 0.37* 55 Thalas 0.52* -0.24 0.50* -0.27 -0.15 56 Thanit -0.23 0.06 0.08 0.39* 0.34* 57 Thanor -0.54* 0.01 0.52* 0.15 0.04 58 Tharot -0.23 0.63* 0.03 -0.01 0.56* 59 Zoofla 0.26 0.15 0.15 -0.17 0.13 * S ign i f i cant at the 2.5% c r i t i c a l l e v e l 62 TABLE 7 C o r r e l a t i o n s with C a n o n i c a l V a r i a t e s N.Str. Georgia and Malaspina Complex A p r i l 22-23 C a n o n i c a l V a r i a t e v1 v2 Comm C o r r e l . C o e f f . ( R ) 0. 40 0, .33 R-squared 0. 16 0, . 1 1 Environment L o c a t i o n 0. 77 -o, .57 0. 91 Depth -0. 12 -0, .49 0. 26 Temperature -0. 08 0, .56 0. 32 S a l i n i t y -0. 74 -0. .66 0. 99 N i t r a t e -0. 62 -o. .16 0. 41 Variance e x t r a c t e d 0. 31 0. .27 0. 58 Phytoplankton P r i n Comp 1 0. 86 -0. .07 0. 74 P r i n Comp 2 -0. 04 •o. .29 0. 08 P r i n Comp 3 -0. 02 -o. .63 0. 40 P r i n Comp 4 -o. 10 -o. .13 0. 03 P r i n Comp 5 -o. 25 -0. .20 0. 10 Redundancy 0. 1 3 0. ,06 0. 19 63 F i g u r e 5 . S p e c i e s C o r r e l a t i o n s w i t h P C ' s I I S I I I NSG vs MC. A p r i l 22-23. 1986. Environmental c o r r e l a t i o n s w i t h each component are d e f i n e d . CO o • o cu o +'ve • NSG su r f a c e -*ve - MC deep M M M U Q. x: * o C o o •r* +J 10 i-» CU CU I* o I 10 Thai08 \ \ \ \ Thanor o '-0.4 Thaecc / Chadeb / / Thaaes Chaeto A / / / / // Fuzzba /// D i c s p e - < ^ - M B 8 r u b fr ^a^" Tharot a a a %• a c a 3 o CD •o CO U CO X z Blenod 1 co a > > -0.2 0.0 0.2 0.4 0.6 0.8 C o r r e l a t i o n w i t h PCII 64 3 3 „ 2 Northern S t r a i t of Georgia The dominants are the same i n A p r i l as they were i n March, but i n a d i f f e r e n t o r d e r : Chrysochromulina (27% of the t o t a l biomass), c i l i a t e s (22%), cryptomonads (19%), and Gyrodinium (12%). A f t e r s e l e c t i o n of those s p e c i e s o c c u r r i n g i n at l e a s t 10% of the samples, the phytoplankton v a r i a b l e s were reduced to 48 from 78. C o l l a p s e d i n t o 5 p r i n c i p a l components i s 49% of the s p e c i e s i n f o r m a t i o n ( c o r r e l a t i o n s t r u c t u r e i n Table 8) which i s used i n the CCA with t r a n s e c t , s t a t i o n , depth, temperature, s a l i n i t y , and n i t r a t e (Table 9). The f i r s t t h ree c a n o n i c a l v a r i a t e s , e x t r a c t i n g 61.6% of the environmental domain's v a r i a n c e , are e x p l a i n i n g 9.0%, 6.6%, and 1.8% of the b i o l o g i c a l v a r i a n c e , r e s p e c t i v e l y . F i g u r e 6 prese n t s s p e c i e s c o r r e l a t i o n s with depth and l o c a t i o n . PCI i s c h a r a c t e r i s e d by CVI (0.53) which i s dominated by the s t a t i o n v a r i a b l e (-0.82) i n d i c a t i n g the western s i d e . Transect (-0.42) a l s o a f f e c t s t h i s v a r i a t e , i n d i c a t i n g a southern t r e n d . In these two d i r e c t i o n s , s a l i n i t y i n c r e a s e s along with n i t r a t e . A l s o c o r r e l a t e d i s CVII (-0.23) which d e s c r i b e s warmer, l e s s s a l i n e s u r f a c e waters of the southern r e g i o n . Species p o s i t i v e l y c o r r e l a t e d with PCI are thus more abundant along the Vancouver I s l a n d s i d e and f u r t h e r south where temperatures are somewhat warmer. They i n c l u d e Th. r o t u l a (0.79), S c r i p p s i e l l a (0.59), A. s p i n i f e r a (0.65), u n i d e n t i f i e d thecate d i n o f l a g e l l a t e s (0.60), T e t r a s e l m i s (0.59), and T. f r a u e n f e l d i i (0.50). Species more a s s o c i a t e d with the deeper e a s t e r n and northern waters are N. p a c i f i c a (-0.50) and a small 65 T h a l a s s i o s i r a sp. (-0.59). I t i s presumed t h a t s p e c i e s are i n o c u l a t e d i n t o the S t r a i t v i a D e s o l a t i o n Sound s i n c e the MC's dominant i s N. p a c i f i c a . Whether or not t h i s diatom . was i n t r o d u c e d from Malaspina or the northern passages i n general i s not known. The MC seems a l i k e l y source as i t s i n t e r n a l c o n c e n t r a t i o n of t h i s diatom was very high and appeared to be r a d i a t i n g outward to D e s o l a t i o n Sound through Malaspina I n l e t . PCII i s p o s i t i v e l y c o r r e l a t e d with CVII (0.67) d e s c r i b i n g the deeper northern waters where Ch. d e b i l i s (0.74), Th. a e s t i v a l i s (0.68), Th. n o r d e n s k i o e l d i i (0.60), E b r i a  t r i p a r t i t a (0.44), Pleurosigma (0.38), L e p t o c y l i n d r u s (0.38), and T. n i t z s c h i o i d e s (0.37) are found. There appears to be no g r a z i n g p r e s s u r e due to P r o t o p e r i d i n i u m . The n e g a t i v e l y c o r r e l a t e d s p e c i e s with t h i s component favour southern s u r f a c e waters and are Micromonas p u s i l i a (-0.55), c i l i a t e s (-0.53), D i c r a t e r i a (-0.48), E u t r e p t i e l l a (-0.41), and cryptomonads (-0.40), again suggesting c i l i a t e s as g r a zers on n a n o f l a g e l l a t e s . PCI 11 i s c o r r e l a t e d to C V s I (0.20) and II (0.18) which r e s p e c t i v e l y d e s c r i b e southwestern waters with higher s a l i n i t i e s and n i t r a t e s , and deeper northern waters with reduced temperatures and i n c r e a s e d s a l i n i t i e s . The two s p e c i e s c o r r e l a t e d with PCIII are M. rubrum (0.66) and Licmophora (0.39). A l l the component-variate c o r r e l a t i o n s are low r e s u l t i n g i n a communality value of .07 which i n d i c a t e s a poor c a n o n i c a l model f o r PCIII. T h i s component i s i n f l u e n c e d by the undoubtedly s i g n i f i c a n t v a r i a n c e i n t r o d u c e d by the unknown "f u z z y " c i l i a t e 66 which appeared i n abundance only i n the su r f a c e waters of Stn 1e. Opposite t h i s c i l i a t e i s the p h o t o s y n t h e t i c Mesodinium. The reason f o r such a s e p a r a t i o n may be n i t r a t e , where high values occur with the former and low valu e s with the l a t t e r . As a l l s i g n i f i c a n t s p e c i e s c o r r e l a t i o n s with PCIV are negati v e , t h i s component i s n e g a t i v e l y a s s o c i a t e d with CVI (0.49) which i s thus d e s c r i b i n g waters of the east and north with reduced s a l i n i t i e s and n i t r a t e s . PCIV i s a l s o a s s o c i a t e d with CVIII (-0.38) which d e s c r i b e s s u r f a c e waters of the west and north with reduced s a l i n i t i e s and n i t r a t e s . M. rubrum (-0.53), Ch. d e c i p i e n s (-0.50), the "f u z z y " c i l i a t e (-0.49), a small T h a l a s s i o s i r a sp. (-0.46), and u n i d e n t i f i e d thecate d i n o f l a g e l l a t e s (-0.40) are s i g n i f i c a n t l y c o r r e l a t e d with these two northern regimes on e i t h e r s i d e of the S t r a i t . PCV i s n e g a t i v e l y c o r r e l a t e d w i t h CVIII (-0.34) which would t r a n s l a t e as deeper SE waters with higher s a l i n i t i e s and n i t r a t e s . A l s o n e g a t i v e l y c o r r e l a t e d i s CVI (-0.29) meaning NE waters with reduced s a l i n i t i e s and n i t r a t e s . Species f a v o u r i n g these e a s t e r n regimes are L e p t o c y l i n d r u s (0.56), z o o f l a g e l l a t e s (0.54), Chrysochromulina (0.48), Th. e c c e n t r i c a (0.39), and M. pusi11a (0.37). Conversely, s p e c i e s p r e f e r r i n g a western regime, with reduced s a l i n i t i e s and n i t r a t e s at the s u r f a c e i n the north and higher s a l i n i t i e s and n i t r a t e s i n the south, are E. t r i p a r t i t a (-0.54) and d i p l o p s a l o i d s (-0.49), two he t e r o t r o p h s . In A p r i l the complexity has i n c r e a s e d s i n c e March even though the major s p e c i e s have remained the same. There are 6 7 d e f i n i t e d i f f e r e n c e s i n s p e c i e s composition from north to south as w e l l as from east to west. A l s o , there i s now a d e f i n i t e deep water assemblage of diatoms which i n h a b i t the northern waters whereas the deeper water s p e c i e s of the south are a mixture of diatoms and n a n o f l a g e l l a t e s . 68 TABLE 8 Species C o r r e l a t i o n s with P r i n c i p a l Components Northern S t r a i t of Georgia, A p r i l , 1 9 8 6 Code Species PCI PCII PCIII PCIV PCV 1 Amph i d 0.01 -0.32 0.20 -0.00 0.23 2 Apedin 0.65* -0.20 0.09 -0.24 -0.25 3 B a l l o o 0.19 -0.07 -0.06 0.16 -0.11 4 Chacnv -0.22 -0.21 -0.21 -0.09 0.36 5 Chadeb 0.13 0.74* 0.08 -0.01 0.09 6 Chadec -0.18 0.25 -0.09 -0.50* -0.22 7 Chaeto 0.06 0.60* -0.08 0.06 -0.25 8 Chasoc 0.35 0.08 0.01 -0.10 0.17 9 Choano -0.07 -0.21 0.04 0.02 0.31 10 Chryso 0.35 -0.32 -0.08 -0.26 0.48* 1 1 C i l i a t 0.40* -0.53* 0.07 -0.14 -0.18 12 C o r c r i 0.17 -0.27 0.12 -0.04 0.30 13 Crypto 0.46* -0.40 -0.03 -0.27 0.27 14 C y l i n d 0.14 -0.01 0.20 0.24 -0.05 15 Detpum 0.42* 0.24 0.20 0.13 0.31 16 D i c r a t 0.39* -0.48* 0.11 -0.04 -0.08 17 Dicspe 0.10 0.36 -0.05 0.17 -0.26 18 D i p l o p 0.35 0.05 0.08 0.16 -0.49* 19 D i t b r i 0.05 0.29 0.16 -0.03 -0.20 20 E b r i a 0.11 0.44* -0.16 -0.17 -0.54* 21 Eutrep 0.42* -0.40* -0.07 -0.11 0.30 22 Fuzzba 0.30 0.19 -0.73* -0.49* 0.01 23 Glenod 0.60* -0.07 0.08 -0.40* -0.02 24 Gymnod 0.27 -0.21 0.22 0.10 0.04 25 Gyrodi 0.39* -0.08 0.09 0.33 -0.25 26 Leptoc 0.20 0.38* -0.07 0.06 0.56* 27 Licmop 0.14 -0.01 0.39* 0.09 0.31 28 Mesrub 0.20 0.00 0.66* -0.53* -0.19 29 Microm 0.25 -0.55 0.03 -0.16 0.37* 30 Navicu 0.30 0.06 -0.18 -0.23 0.17 31 Nitpac -0.50* 0.10 0.23 -0.17 0.28 32 N i t z s c 0.18 0.25 -0.04 0.24 -0.15 33 Pennat 0.07 -0.35 -0.20 -0.12 -0.04 34 Pleuro 0.06 0.38* 0.04 0.08 0.03 35 Protop 0.39* -0.22 0.11 0.08 -0.11 36 R h i f r a 0.45* 0.36 -0. 16 0.10 0.12 37 S c r i p p 0.65* 0.16 -0.08 0.08 -0.10 38 Skecos 0.26 0.11 -0.22 0.09 -0. 15 39 S t e n i p 0.05 0.29 -0.21 -0.11 -0.06 40 T e t r a s 0.56* -0.34 -0.23 0.26 0.09 41 Thaaes 0.20 0.68* 0.13 0.29 -0.11 42 Thaecc -0.15 0.24 -0.05 -0.01 0.39* 43 Thafra 0.50* 0.03 0.20 0.09 -0.02 44 Thalas -0.59* 0.30 0.08 -0.46* 0.19 45 Than i t 0.37* 0.37* 0.21 0.25 -0.20 46 Thanor -0.04 0.60 -0.02 0.16 0.34 47 Tharot 0.79* 0.14 0.24 -0.17 0.30 48 Zo o f l a 0.03 0.03 -0.05 0.02 0.54* * S i g n i f i c a n t at the 2.5% c r i t i c a l l e v e l 69 TABLE 9 C o r r e l a t i o n s with C a n o n i c a l V a r i a t e s Northern S t r a i t of Georgia A p r i l 22-23 Ca n o n i c a l V a r i a t e v i v2 v3 Comm C o r r e l . C o e f f . ( R ) 0. 37 0. 34 0. 24 R-squared 0. 13 0. 1 1 0. 06 Environment Transect -0. 42 0. 77 0. 40 0.92 S t a t i o n -0. 82 - o . 16 - o . 55 0.99 Depth 0. 14 0. 40 - o . 44 0.37 Temperature 0. 1.5 -0. 39 -0. 1 1 0.19 S a l i n i t y 0. 44 0. 86 - o . 21 0.99 N i t r a t e • 0. 27 0. 09 - o . 39 0.23 V a r i a n c e e x t r a c t e d 0. 19 0. 28 0. 14 0.61 Phytoplankton P r i n Comp I 0. 53 -0. 23 0. 1 1 0.35 P r i n Comp II 0. 17 0. 67 0. 16 0.51 P r i n Comp III 0. 20 0. 18 - o . 00 0.07 P r i n Comp IV 0. 49 0. 06 -0. 38 0.38 P r i n Comp V -0. 29 0. 19 - o . 34 0.23 Redundancy 0. 09 0. 07 0. 02 0.18 70 F i g u r e 6. S p e c i e s C o r r e l a t i o n s w i t h P C ' s I I S I I I N.Str.Georgia, A p r i l 22-23. 19B6. Environmental c o r r e l a t i o n s w i t h each component are d e f i n e d . 03 o (0 o* +'ve - North deep -*ve - South surface M ° CJ Q_ JC C o cu o o o M88PUb Llcmop ll n D c o c a? n Thanit io cu Dicrat C l l i a t — Microffl Crypto-Eutrep Thaaea (0 c c o CJ o I o I to o I ^ _ — Chadab ^ . a - C — — ~ P l e u r o i o — — y — Thanor an \ —_ LsBtoc""""" ^ Lap toe ""chaeto Ebrla 0 n o o o a rt c o +» e a 0 *> o n c 0 *» S c * J2 +> z 3 O . CO 0 u . 0 a *-0 c 0 3 -a o c c *J *1 fc. 3 o o Z CO 0 0 > > o '-0.6 Puzzba I _L -0.4 -0.2 0.0 0.2 0.4 C o r r e l a t i o n w i t h PCII 0.6 71 3.1.4 June, 1986 N . S t r a i t of Georgia vs Malaspina Complex Data r e d u c t i o n v i a PCA was performed as p r e v i o u s l y and the sp e c i e s i n f o r m a t i o n c o l l a p s e d i n t o 5 p r i n c i p a l components acco u n t i n g f o r 57% of the v a r i a n c e . The r e s u l t a n t c o r r e l a t i o n s t r u c t u r e i s presented i n Table 10. The r e s u l t s of the c a n o n i c a l c o r r e l a t i o n a n a l y s i s of these f i v e components with l o c a t i o n , depth, temperature, s a l i n i t y , and n i t r a t e are presented as a c a n o n i c a l s t r u c t u r e i n Table 11. The f i r s t two c a n o n i c a l v a r i a t e s e x p l a i n 12.3% and 8.0% of the b i o l o g i c a l v a r i a n c e while a l l o t h e r s f o l l o w i n g have very s m a l l redundancies. T h e r e f o r e , only the f i r s t two v a r i a t e s are presented, e x t r a c t i n g 80.3% of the environmental domain's v a r i a n c e . Species c o r r e l a t i o n s with depth and l o c a t i o n are presented i n F i g u r e 7. Once again there are many s i g n i f i c a n t c o r r e l a t i o n s between s p e c i e s and PCI, i n d i c a t i n g biomass. T h i s component i s p o s i t i v e l y c o r r e l a t e d with CVI (0.54) and CVII (0.60). The former c a n o n i c a l v a r i a t e i s b a s i c a l l y one c h a r a c t e r i s i n g the upper s t r a t i f i e d waters of the MC as i n d i c a t e d by higher temperatures (0.58), lower s a l i n i t i e s (-0.54), and very low n i t r a t e (-0.74) while the l a t t e r i s very s i m i l a r i n that i t c h a r a c t e r i s e s the upper s t r a t i f i e d NSG waters with higher temperatures (0.66), lower s a l i n i t i e s (-0.50), and low n i t r a t e (-0.63). The main d i f f e r e n c e between these v a r i a t e s i s the c o n t r i b u t i o n of the depth v a r i a b l e i n that the NSG i s c h a r a c t e r i s e d by strong s p e c i e s s t r a t i f i c a t i o n near the su r f a c e (depth = -0.82). T h e r e f o r e , PCI i s not d i s t i n g u i s h i n g between 72 l o c a t i o n so much as c h a r a c t e r i s i n g the upper s t r a t i f i e d waters common to both areas at t h i s time of year. The s p e c i e s most h i g h l y c o r r e l a t e d with t h i s s u r f a c e s p e c i e s component are Heterocapsa t r i q u e t r a (0.89), c i l i a t e s (0.88), Protogonyaulax  c a t e n e l l a (0.87), Dinophysis (0.83), and A p e d i n e l l a s p i n i f e r a (0.83). Not s u r p r i s i n g l y , the m a j o r i t y of p o s i t i v e c o r r e l a t i o n s are with f l a g e l l a t e d s p e c i e s which are able to take advantage of these summer s t r a t i f i e d waters. The only s i g n i f i c a n t negative c o r r e l a t i o n s , i n d i c a t i n g an absence from these c o n d i t i o n s , are with Chaetoceros convolutus (-0.41) and A s t e r i o n e l l a q l a c i a l i s (-0.34). T h i s i s c o n s i s t e n t with the e x p e c t a t i o n that diatoms w i l l sink out of calm, n i t r a t e - d e p l e t e d s u r f a c e waters. PCII i s n e g a t i v e l y c o r r e l a t e d with CVI (-0.66), denoting intermediate waters of the NSG where temperatures are lower and s a l i n i t i e s and n i t r a t e s h i g h e r , and p o s i t i v e l y with CVII (0.45), the s u r f a c e waters of the NSG. Together, the focus seems to be on NSG waters and the s p e c i e s that are found mostly i n s u r f a c e waters and a l s o at depth. Such organisms are E n s i c u l i f e r a (0.55), Ochromonas (0.51), D i c r a t e r i a (0.42), and Gyrodinium (0.33). Conversely, s p e c i e s which are found mostly i n the MC's deeper waters and to a l e s s e r extent i t s s u r f a c e waters i n c l u d e z o o f l a g e l l a t e s other than c h o a n o f l a g e l l a t e s (-0.64), Micracanthadinium (-0.61), Oxyphysis oxytoxoides (-0.56), Pleurosiqma (-0.51), S c r i p p s i e l l a (-0.45), and N o c t i l u c a  s c i n t i l l a n s (-0.42). In g e n e r a l , these organisms are those of PCI's s u r f a c e s p e c i e s assemblage which are able to u t i l i s e depths below the upper zone of s t r a t i f i c a t i o n . I t would appear 73 that s p e c i e s of the NSG are more s u r f a c e a s s o c i a t e d than those i n the MC. PCIII has a weak c o r r e l a t i o n with CVII (0.24), the s t r o n g l y s u r f a c e - a s s o c i a t e d NSG v a r i a t e . The organisms of t h i s group are c h a r a c t e r i s e d by the misc e l l a n e o u s z o o f l a g e l l a t e s (0.47), O. oxytoxoides (0.45), Detonula pumila (0.42), C o s e i n o d i s c u s (0.37), and Prorocentrum q r a c i l e (0.33). Negative c o r r e l a t i o n s i n d i c a t e a st r o n g tendency towards depth and are more l i k e l y found i n the MC (e.g., Katodinium rotundatum (-0.48) and S c r i p p s i e l l a t r o c h o i d e a (-0.40)). PCIV i s not c o r r e l a t e d with e i t h e r v a r i a t e and i s thus f i n d i n g s p e c i e s s e p a r a t i o n based on some other e c o l o g i c a l i n d i c a t o r . P o s i t i v e l y c o r r e l a t e d are P. g r a c i l e (0.39) while most c o r r e l a t i o n s are negat i v e , i n c l u d i n g Amphidinium (-0.43), Mesodinium rubrum (-0.32) and v a r i o u s diatoms. PCV i s another component which i s hard to i n t e r p r e t . One can say that when Pleurosiqma occurs (0.39), a host of other diatoms, as w e l l as Pyramimonas (-0.45) and P o l y k r i k o s k o f o i d i i (-0.33), do not. There i s a weak c o r r e l a t i o n with CVI (0.21) so th a t Pleurosiqma may be more abundant i n upper waters of the MC while the other diatoms are more depth s p e c i f i c i n the NSG. I t i s i n t e r e s t i n g to note that P. k o f o i d i i , a h e t e r o t r o p h i c d i n o f l a g e l l a t e , i s o c c u r r i n g with these other s p e c i e s . The phytoplankton have d e f i n i t e l y become more d i v e r s e s i n c e s p r i n g and the environmental i n t e r a c t i o n s have i n c r e a s e d the system's v e r t i c a l b i o l o g i c a l complexity. In June there i s a major d i s c r i m i n a t i o n of s u r f a c e s t r a t i f i e d waters with t h e i r 74 i n c r e a s e d temperatures, reduced s a l i n i t i e s , and reduced n i t r a t e s . W i t hin t h i s s t r a t i f i e d zone some organisms are more s p e c i f i c to e i t h e r the NSG or MC. In g e n e r a l , however, the two s t r a t i f i e d regimes share many of the s t a b l e community s p e c i e s . 75 TABLE 10 Species Corre la t ions with P r i n c i p a l Components N .Str .Georg ia and Malaspina, June,1986 Code Spec ies PCI PCII PCIII PCIV PCV 1 Actund 0.18 -0.54* 0.14 -0.30 0.01 2 Alexan 0.35* -0.45* 0.16 -0.26 -0.26 3 Amphid 0.53* 0.11 0.00 -0.43 0.08 4 Apedin 0.82* 0.16 0.10 0.16 -0.10 5 Astgla -0.34* 0.02 -0.10 -0.06 -0.20 6 Cerat i 0.75* -0.16 -0.02 0.07 0.04 7 Chacnv -0.41* 0.20 -0 . 1 3 -0.26 0.09 8 Chadeb -0.10 -0.01 0.23 -0.25 -0.53* 9 Chaeto -0.02 -0.06 0.25 0.04 -0.43* 10 Choano -0.02 -0.06 0.27 -0.19 0.00 1 1 Chryso 0.74* -0.27 0.26 0.15 -0.10 12 C i l i a t 0.88* 0.22 -0.07 0.00 -0.08 13 Cose in 0.20 -0.01 0.37* -0.42* 0.18 1 4 Crypto 0.79* 0.13 0.06 -0.10 0.01 15 Cy l ind -0.30 0.16 0. 1 4 -0.23 -0.20 16 Detpum 0.09 -0.22 0.42* -0.10 -0.28 17 Dicrat 0.41* 0.42* 0.05 0.10 -0.35* 18 Dicspe 0.65* 0.23 -0.23 -0.25 0.03 19 Dinoph 0.83* -0.19 0.06 -0.12 0.16 20 Diplop 0.22 -0.10 -0.31 -0.12 -0.28 21 Ensicu 0.52* 0.55* 0.22 -0.32 0.03 22 Euczoo 0.11 0.17 -0.00 -0.28 -0.41* 23 Eutrep 0.77* 0.03 0.11 -0.00 -0.01 24 Glenod 0.79* 0.20 -0 . 14 -0.09 -0.07 25 Gonyau 0.71* 0.10 -0.16 -0.22 0.29 26 Gymnod 0.75* 0.19 0.13 0.01 0.12 27 Gyrodi 0.66* 0.33* -0.01 0.23 -0.08 28 Hetaka 0.35* -0.08 -0.12 0.12 -0.15 29 Hetmas 0.58* -0.15 0.26 0.09 0.25 30 H e t t r i 0.89* 0.08 -0.02 0.12 -0.10 31 Katodi 0.32 0.20 -0.48* -0.09 0.04 * S ign i f i cant at the 2.5% c r i t i c a l l eve l 76 TABLE 10 (Cont'd) Species Corre la t ions with P r i n c i p a l Components N .Str .Georg ia and Malaspina, June,1986 Code Spec ies PCI PCII PCI 11 PCIV PCV 32 Leptoc -0.18 0.09 0.23 -0.39* -0.43* 33 Mesrub 0.57* -0.05 0.28 -0.32 0.26 34 Micrac 0.36* -0.61* 0.26 0.27 -0.02 35 Microf 0.34* -0.70* -0.34* -0.08 -0.26 36 Microm 0.46* 0.1 4 0.15 0.00 -0.06 37 Navicu -0.24 -0.23 -0.04 -0.25 -0.24 38 Nitpac -0.31 0.08 0.18 -0.46* -0.25 39 Nitzsc -0.21 -0.09 0.04 -0.35* -0.23 40 Nocsci 0.63* -0.42* 0.29 0.14 -0.06 41 Ochrom 0.41* 0.51* 0.21 0.23 -0.11 42 Oxyoxy 0.38* -0.56* 0.45* 0.10 -0.20 43 Pleuro -0.09 -0.51* 0.28 -0.21 0.39* 44 Polkof 0.47* 0.25 -0.30 0.06 -0.33* 45 Procat 0.87* -0.19 0.00 0. 14 0.08 46 Progrc 0.59* -0.30 0.33* 0.39* -0.14 47 Protam 0.67* -0.10 -0.32 0.19 0.08 48 Protop 0.77* 0.06 0.05 -0.04 0.01 49 Pyrami 0.12 0.08 -0.09 0.01 -0.45* 50 Rhidel 0.19 -0.13 0.06 -0.40* 0.05 51 Rhi fra -0.18 -0.24 -0.00 0.03 -0.09 52 Rhiset -0.03 -0.22 0.27 -0.50* -0.44* 53 Rhizos -0.08 -0.35* -0.27 -0.14 0.04 54 Scripp 0.59* -0.45* -0.40* -0.14 0.10 55 Skecos -0.36* 0.07 -0.27 -0.12 -0.19 56 Tetras 0.79* 0.29 0.16 0.03 -0.04 57 Thaecc -0.43* -0.37* -0.12 -0.21 0.05 58 Thafra -0.44* 0.00 -0.13 -0 . 17 0.03 59 Thalas 0.48* 0.01 -0.03 -0.38* 0. 17 60 Thanit -0.30 0.15 0.01 -0.11 -0.37* 61 Tharot -0.18 -0.31 -0.17 -0.22 0.09 62 Zoofla 0.25 -0.64* 0.47* 0.12 0.10 * S i g n i f i c a n t at the 2.5% c r i t i c a l l e v e l TABLE 11 Corre la t ions with Canonical Var iates N . S t r . Georgia and Malaspina Complex June 25-26 Canonical Variate v1 v2 Comm C o r r e l . C o e f f . ( R ) 0. 40 0. 36 R-squared 0. 16 0. 1 3 Environment Location 0. 85 -0 . 48 0.96 Depth -0 . 38 -0 . 82 0.81 Temperature 0. 58 0. 66 0.77 S a l i n i t y -0 . 54 - o . 50 0.54 Ni tra te - 0 . 74 - o . 63 0.94 Variance extracted 0. 41 0. 39 0.80 Phytoplankton Prin Comp I 0. 54 0. 60 0.66 Pr in Comp II -0 . 66 0. 45 0.64 Pr in Comp III -0 . 06 0. 24 0.06 Pr in Comp IV -0 . 04 -0 . 01 0.00 Prin Comp V 0. 21 -0 . 08 0.05 Redundancy 0. 12 0. 08 0.20 78 F i g u r e 7. S p e c i e s C o r r e l a t i o n s w i t h P C ' s I I S I I I NSG vs MC, June 25-26. 1986. Environmental c o r r e l a t i o n s w i t h each component are d e f i n e d . +'ve - NSG deep and surface -'ve - MC surface and deep Zoofla oxyoxy X Pleuro Micrac v Oetpum \ Progrc \ Coscln Nocaci \ Alexen Actund-. ^ a ^. V <>lv V \ En8icu Ochrom •icrat 6yrodi Thaecc Microf o '-O.B Rhlzoa / / / Scrlpp Katodi o o o u 3 n o o a TJ CD CO CJ Z X a> > « > -0.6 -0.4 -0.2 0.0 0.2 C o r r e l a t i o n w i t h PCII 0.4 7 9 3_. J _ . 4 . 2: Northern S t r a i t of Georgia At the sampling time i n June, the NSG was dominated by c i l i a t e s on a biomass b a s i s ( 4 4 % ) followed by Heterosigma  akashiwo ( 1 1 % ) , Gyrodinium ( 1 0 % ) , and cryptomonads ( 7 % ) . The dominants are s t i l l very s i m i l a r t o A p r i l . U n l i k e March and A p r i l , the percent occurrence used to reduce the phytoplankton v a r i a b l e s below the number of cases ( 4 8 ) before employing the PCA was 3 0 % . T h i s a c t i o n reduced the v a r i a b l e s from 7 8 to 4 8 . The f i r s t 5 p r i n c i p a l components c o n t a i n 66% of the s p e c i e s i n f o r m a t i o n and the c o r r e l a t i o n s t r u c t u r e i s shown in Table 1 2 . These components were then used i n a CCA with the environmental v a r i a b l e s t r a n s e c t , s t a t i o n , depth, temperature, s a l i n i t y , and n i t r a t e . The c a n o n i c a l s t r u c t u r e i s presented i n Table 1 3 . The f i r s t two c a n o n i c a l v a r i a t e s have been r e t a i n e d f o r i n t e r p r e t a t i o n , e x t r a c t i n g 7 1 . 4 % of the environmental v a r i a n c e and i n d i v i d u a l l y e x p l a i n i n g 1 2 . 8 % and 7 . 8 % of the b i o l o g i c a l v a r i a n c e . N o t i c e the i n t e r s e t communality f o r the s t a t i o n v a r i a b l e which i s only 1 8 . 6 % accounted f o r i n the r e t a i n e d environmental domain. F i g u r e 8 p r e s e n t s s p e c i e s c o r r e l a t i o n s with depth and l o c a t i o n . PCI i s p o s i t i v e l y c o r r e l a t e d with CVI ( 0 . 8 2 ) which d e s c r i b e s NW s u r f a c e waters where temperatures are e l e v a t e d , s a l i n i t i e s low, and n i t r a t e s reduced. PCI i s a l s o n e g a t i v e l y c o r r e l a t e d with CVII ( - 0 . 3 1 ) though not as s t r o n g l y as with CVI. T h i s l a t t e r v a r i a t e d e s c r i b e s southern s u r f a c e waters with e l e v a t e d temperatures and reduced s a l i n i t i e s and n i t r a t e s . Together then, PCI s p e c i e s with p o s i t i v e c o r r e l a t i o n s are those 80 that occupy the NSG's upper, s t r a t i f i e d waters, e s p e c i a l l y i n the northwest where high biomass of most groups o c c u r s . Such sp e c i e s i n c l u d e H. t r i q u e t r a (0.93), c i l i a t e s (0.92), P. c a t e n e l l a (0.87), A. s p i n i f e r a (0.86), T e t r a s e l m i s (0.85), and u n i d e n t i f i e d thecate d i n o f l a g e l l a t e s (0.85). The negative c o r r e l a t i o n s are going to be s p e c i e s of the deep water diatom community, e s p e c i a l l y i n the SE, and are T h a l a s s i o s i r a  e c c e n t r i c a (-0.45) and T h a l a s s i o t h r i x f r a u e n f e l d i i (-0.41). PCII i s p o s i t i v e l y c o r r e l a t e d with CVII (0.65) denoting northern deep waters with lower temperatures and higher s a l i n i t i e s and n i t r a t e s . Of l e s s magnitude i s PCII's c o r r e l a t i o n with CVI (0.34) which denotes NW s u r f a c e waters as above. Micromonas p u s i l l a (0.81), S. t r o c h o i d e a (0.58), a R h i z o s o l e n i a sp. (0.51), Protogonyaulax tamarensis (0.46), and H. akashiwo (0.45) are favoured i n these northern waters whereas E n s i c u l i f e r a (-0.49) and Ochromonas (-0.46) occur i n southern waters. PCIII i s responding to CVII (-0.19), the southern s u r f a c e water v a r i a t e . These s u r f a c e waters are c h a r a c t e r i s e d by R h i z o s o l e n i a s e t i g e r a (0.72), N i t z s c h i a spp. (0.59), L e p t o c y l i n d r u s (0.55), N i t z s c h i a pac i f i c a (0.52), and E. zoodiacus (0.41). There are no s i g n i f i c a n t negative c o r r e l a t i o n s . PCIV i s n e g a t i v e l y c o r r e l a t e d with CVII (-0.20), the southern s u r f a c e water v a r i a t e . Species f a v o u r i n g these waters are m i s c e l l a n e o u s Chaetoceros spp. (0.44), P. g r a c i l e (0.43), and Ochromonas (0.40). Negative c o r r e l a t i o n s d e s c r i b e s p e c i e s 81 found i n northern waters: Gonyaulax (-0.45) and E n s i c u l i f e r a (-0.37). Obviously, t h i s l a t t e r d i n o f l a g e l l a t e must be found throughout the NSG as above i t was found to be s i g n i f i c a n t l y a s s o c i a t e d with the south. I t i s not i n c o n c e i v a b l e to have a bimodal d i s t r i b u t i o n of E n s i c u l i f e r a . PCV i s p o s i t i v e l y c o r r e l a t e d with CVII (0.16), here i n d i c a t i n g northern deep water. The only s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n i s that of M. rubrum (0.36). The only negative a s s o c i a t i o n i s that of E. zoodiacus (-0.41) making t h i s diatom more i n d i c a t i v e of southern s u r f a c e waters as above. June pres e n t s a p i c t u r e whereby the e n t i r e s t r a i t i s i n an advanced stage of s t a b i l i t y , with a host of f l a g e l l a t e d organisms occupying the upper waters (Margalef, 1958). There are deep water diatom communities but these are reduced i n numbers as w e l l as d i v e r s i t y . There a l s o seem to be north-south and east-west d i f f e r e n c e s i n s p e c i e s composition, although no adequate e x p l a n a t i o n as to why these p a t t e r n s e x i s t i s obtained from t h i s a n a l y s i s . I t appears that the northwest i s important to biomass generation which probably occurs v i a the t i d a l j e t ' s n u t r i e n t pump-turbulence a c t i o n i n an otherwise s t a b l e water body. Aside from t h i s , n orth-south d i f f e r e n c e s account f o r the S t r a i t ' s remaining s p e c i e s d i f f e r e n c e s with very l i t t l e east-west v a r i a b i l i t y . 82 TABLE 12 Species C o r r e l a t i o n s with P r i n c i p a l Components Northern S t r a i t of Georgia, June,1986 Code Spec i e s PCI PCII PCIII PCIV PCV 1 Amphid 0.61* -0.06 0.37* -0.29 0.13 2 Apedin 0.86* -0.07 -0.14 -0.07 -0.18 3 C e r a t i 0.76* 0.09 -0.12 0.09 -0.27 4 Chacnv -0.36 -0.08 0.24 -0.15 0.16 5 Chaeto -0.12 -0.03 0.29 0.44* -0.14 6 Choano -0.04 -0.09 0.02 -0.15 0.07 7 Chryso 0.74* -0.06 0.06 0.27 -0.23 8 C i l i a t 0.92* -0.03 0.08 -0.00 -0.02 9 Cose i n 0.20 -0.25 0.04 -0.06 0.34 10 Crypto 0.81* -0.16 0.13 -0.01 -0.05 1 1 C y l i n d -0.25 -0.21 0.32 -0.01 0.02 12 D i c r a t 0.66* -0.06 0.11 0.38* -0.04 13 Dicspe 0.82* -0.01 0.17 -0.19 -0.22 14 Dinoph 0.83* -0.04 0.04 -0.23 -0.00 15 D i p l o p 0.33 0.29 0.40* 0.24 0.29 16 E n s i c u 0.62* -0.49* 0.09 -0.37* -0.11 1 7 Euczoo 0.10 0.00 0.41* -0.09 -0.40* 18 Eutrep 0.78* -0.07 -0.08 0.09 0.06 19 Glenod 0.85* -0.05 0.23 -0.04 -0.03 20 Gonyau 0.71* 0.02 -0.01 -0.45* 0.20 21 Gymnod 0.79* -0.24 -0.10 0.08 0.06 22 Gyrodi 0.72* -0.16 -0.17 0.15 0.09 23 Hetaka 0.18 0.45* 0.05 -0.01 0.10 24 Hetmas 0.61* -0.18 -0.17 0.11 0.19 25 H e t t r i 0.93* 0.05 -0.05 0.12 -0.13 26 Leptoc -0.21 -0.15 0.55* 0.15 -0.00 27 Mesrub 0.71* -0.27 0.12 -0.04 0.36 28 Mi c r o f 0.28 0.81* 0.21 -0.03 -0.28 29 Microm 0.54* -0.07 -0.04 0.34 -0.05 30 Nitpac -0.21 -0.29 0.52* 0.12 -0.05 31 N i t z s c -0.12 0.00 0.59* 0.26 0.19 32 Nocsci 0.64* 0.14 -0.06 0.20 -0.13 33 Ochrom 0.47* -0.46* 0.07 0.40* 0. 12 34 Polkof 0.61* 0.13 0.22 0.34 0.35 35 Procat 0.87* 0.13 -0.21 0.21 -0.01 36 Progrc 0.52* -0.11 -0.15 0.43* -0.21 37 Protam 0.70* 0.46* -0.35 0.11 0.12 38 Protop 0.80* -0.10 0.00 0.02 0.07 39 R h i d e l 0.31 -0.03 0.25 0.19 0.20 40 Rhi s e t -0.03 -0.05 0.72* 0.19 -0.19 41 Rhizos -0.06 0.51* 0.19 -0.03 0.02 42 S c r i p p 0.52* 0.58* 0.11 -0.31 0.31 43 Skecos -0.28 0.34 0.05 -0.08 -0.03 44 T e t r a s 0.85* -0.22 -0.04 0.08 -0.02 45 Thaecc -0.45* 0.33 0.09 0.02 -0.11 46 Thafra -0.41* 0.03 0.06 -0.23 0.11 47 Thai as. 0.61* -0.14 0.20 -0. 14 -0.22 48 Than i t -0.25 -0.03 0.28 0.22 0.01 * S i g n i f i c a n t at the 2.5% c r i t i c a l l e v e l TABLE 13 Corre la t ions with Canonical Var iates Northern S t r a i t of Georgia June 25-26 Canonical Var iate v1 v2 Comm C o r r e l . C o e f f . ( R ) 0. 40 0. 35 R-squared 0. 16 0. 12 Environment Transect 0. 51 0. 77 0.86 Stat ion -0 . 43 -o. 07 0.19 Depth -0 . 68 0. 60 0.83 Temperature 0. 71 -o. 56 0.81 S a l i n i t y -0 . 65 0. 58 0.76 Ni tra te -0 . 79 0. 47 0.85 Variance extracted 0. 41 0. 31 0.72 Phytoplankton Prin Comp I 0. 82 -0 . 31 0.77 Prin Comp II 0. 34 0. 65 0.54 Prin Comp III -0 . 10 -0 . 19 0.05 Prin Comp IV -0 . 07 -o. 20 0.05 Prin Comp V -0 . 01 0. 16 0.03 Redundancy 0. 13 0. 08 0.21 84 F i g u r e B . S p e c i e s C o r r e l a t i o n s w i t h P C ' s I I S I I I N.Str.Georgia. June 25-26. 1986. Environmental c o r r e l a t i o n s w i t h each component are d e f i n e d . CJ Q. JC •P c o 1-t 4J ID t-t CU c t_ o CJ CO o 10 o cu o o d cu o I +'ve - Northwest surface, North deep -*ve - Southeast deep. South surface Nltpac Rhlset I I I Nltzsc Leptoc | | I I I I I I I I Euczoo Ensleu Ochrom Amphld • • • I \ I II nil \ in \ \in \ tin \ tin Ml Dlplop / Rhizos Mlcrof \ ! / Hetaka —fy&s&z 0 o 0 »- a c o 3 O o n c c *> 4J 3 C O O CO z 0 o > > V o '-0. Protam J 6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 C o r r e l a t i o n w i t h PCII 85 3.1.5 August, 1986 3.1.5.1 N . S t r a i t of Georgia vs Malaspina Complex The data r e d u c t i o n was b a s i c a l l y the same as f o r the p r e v i o u s months except that the cut o f f f o r the percentage occurrence l e v e l was i n c r e a s e d to 25% because the s p e c i e s i n v o l v e d were much more numerous and the biomass more evenly d i s t r i b u t e d among them. T h i s a c t i o n was necessary i n order to reduce the number of b i o l o g i c a l v a r i a b l e s below the number of cases ( s t a t i o n samples). Because of t h i s i n c r e a s e d d i v e r s i t y there was l e s s cumulative v a r i a n c e e x t r a c t e d by the f i r s t f i v e p r i n c i p a l components (48%) than p r e v i o u s l y . A l s o the f i r s t component has only e x t r a c t e d 16% of the o v e r a l l v a r i a n c e . The c o r r e l a t i o n s t r u c t u r e f o r the PCA i s shown i n Table 14 and the r e s u l t s of the CCA are given i n Table 15. The f i r s t four c a n o n i c a l v a r i a t e s c o n t r i b u t e s i g n i f i c a n t l y to e x p l a i n i n g the b i o l o g i c a l domain's v a r i a n c e and are thus r e t a i n e d . Together they e x t r a c t 97.2% of the environmental v a r i a n c e and s e p a r a t e l y e x p l a i n 12.6%, 6.7%, 3.4%, and 1.1% of the b i o l o g i c a l v a r i a n c e . Up t i l l now, t h i s a n a l y s i s has had only two important c a n o n i c a l v a r i a t e s . F i g u r e 9 p r e s e n t s s p e c i e s c o r r e l a t i o n s with depth and l o c a t i o n . PCI i s c h a r a c t e r i s e d p o s i t i v e l y by CVIV (0.39) and n e g a t i v e l y by CVIII (-0.37). The former v a r i a t e appears to be d e s c r i b i n g s u r f a c e waters with higher s a l i n i t i e s and reduced n i t r a t e whereas the l a t t e r being negative i s s o l e l y concerned with waters of lower s a l i n i t i e s and lower n i t r a t e . B a s i c a l l y , the two together are saying that the PCI s p e c i e s are o c c u r r i n g 86 i n a l l s a l i n i t i e s and that t h e i r growth i s reducing the n i t r a t e . The m a j o r i t y of sp e c i e s i n t h i s regime are diatoms that have presumably broken the s o l e dominance of June's m o t i l e organisms. The p o s i t i v e l y c o r r e l a t e d s p e c i e s with PCI i n c l u d e N i t z s c h i a  p a c i f i c a (0.85), Chaetoceros d e b i l i s (0.79), C y l i n d r o t h e c a (0.78), Skeletonema costatum (0.76), Ch. s o c i a l i s (0.76), and A s t e r i o n e l l a g l a c i a l i s (0.75) as w e l l as the overwhelming bulk of Chaetoceros s p e c i e s dominating the phytoplankton biomass. N o t i c e there are v i r t u a l l y no negative c o r r e l a t i o n s . PCII i s mainly dominated by CVI (0.65) which i s a s s o c i a t e d with deeper waters and t h e i r reduced temperatures and e l e v a t e d s a l i n i t i e s and n i t r a t e v a l u e s . CVII (-0.44) a l s o a f f e c t s t h i s component and i s i n d i c a t i v e of s p e c i e s belonging to one of the two r e g i o n s . T h e r e f o r e , PCII appears to be d i s t i n g u i s h i n g s p e c i e s c h a r a c t e r i s t i c of the NSG's deeper water community. The most h i g h l y c o r r e l a t e d are N i t z s c h i a spp. (0.53), Ch. convolutus (0.50), T r o p i d o n e i s l e p i d o p t e r a (0.48), n a v i c u l o i d s (0.45), m i s c e l l a n e o u s pennate diatoms (0.43), and A. g l a c i a l i s (0.40). The negative c o r r e l a t i o n s are probably s p e c i e s common i n the MC's s u r f a c e waters and i n c l u d e Alexandrium o s t e n f e l d i i (-0.64), Ceratium (-0.64), R h i z o s o l e n i a s e t i g e r a (-0.57), Chrysochromulina (-0.56), m i s c e l l a n e o u s n a n o f l a g e l l a t e s (-0.55), T e t r a s e l m i s (-0.54), R. d e l i c a t u l a (-0.54), and Micromonas  p u s i l i a (-0.51). PCIII i s c h a r a c t e r i s e d by the same two c a n o n i c a l v a r i a t e s as the l a s t component except that the c o r r e l a t i o n with CVII (0.50) has i n c r e a s e d i n magnitude and the d i r e c t i o n i s reversed 87 ( i . e . , p o s i t i v e i n s t e a d of n e g a t i v e ) . One would assume t h i s to mean that PCI II i s d e s c r i b i n g the deep water community of the MC. Here the s p e c i e s are Actinoptychus undulatus (0.65), T h a l a s s i o s i r a a e s t i v a l i s (0.62), Th. a n q s t i i (0.53), T h a l a s s i o t h r i x f r a u e n f e l d i i (0.50), and R. s e t i q e r a (0.41). A l t e r n a t i v e l y , the n e q a t i v e l y c o r r e l a t e d s p e c i e s of the NSG's upper waters are S c r i p p s i e l l a t r o c h o i d e a (-0.70), Prorocentrum  q r a c i l e (-0.53), Dinophysis (-0.51), c i l i a t e s (-0.44), gymnodinoids (-0.39), Ochromonas (-0.39), Heterosigma akashiwo (-0.34), and Gonyaulax (-0.34). I t would appear from these two components that there i s s p e c i e s s t r a t i f i c a t i o n i n both areas, c h a r a c t e r i s e d by f l a g e l l a t e d forms i n the s u r f a c e waters and diatoms i n the deeper, n u t r i e n t - r i c h waters. The s p e c i e s compositions of these two zones, however, are d i f f e r e n t f o r the two ar e a s . PCIV i s most c o r r e l a t e d with CVIII (0.48) which i s the higher s a l i n i t y , n i t r a t e r e p l e t e v a r i a t e , but CVI which e x p l a i n s more of the b i o l o g i c a l v a r i a n c e , i s a l s o c o r r e l a t e d (-0.21). PCIV i s probably best d e s c r i b e d as corresponding to deeper waters i n g e n e r a l , with a small c o n t r i b u t i o n from the MC's s u r f a c e waters (CVIV=.28). The only s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s with PCIV are H. akashiwo (0.49) and Chaetoceros  e i b e n i i (0.33), a diatom which was f a i r l y s p e c i f i c to the MC. Organisms c o r r e l a t e d with the lower s a l i n i t y , n i t r a t e reduced c o n d i t i o n s i n upper l a y e r s are Mesodinium rubrum (-0.55). Pleurosigma (-0.54), and Cose i n o d i scus (-0.52). From past a n a l y s e s , M. rubrum was found a s s o c i a t e d with upwelling 88 c o n d i t i o n s but here the s a l i n i t y - n i t r a t e p a t t e r n i s not that of u p w e l l i n g . However, upw e l l i n g might h e l p keep such heavy diatoms as Pleurosiqma and C o s c i n o d i s c u s suspended. PCV i s simply i s o l a t i n g a s e c t i o n of the MC's waters (from CVII (0.32)) which i s c h a r a c t e r i s e d by Ch. e i b e n i i (0.41). The negative PC c o r r e l a t i o n s i n d i c a t e an absence of these s p e c i e s from t h i s area and are probably not e c o l o g i c a l l y meaningful. O v e r a l l , t h i s a n a l y s i s was most i n f o r m a t i v e i n d e s c r i b i n g PC's II and III which had 65.6% and 58.1% of t h e i r r e s p e c t i v e v a r i a n c e s e x p l a i n e d by the two c a n o n i c a l v a r i a t e s . I t shows an i n c r e a s i n g complexity compared to June. There seemed to be d e f i n i t e s t r a t i f i e d communities with f l a g e l l a t e d forms found c h i e f l y i n upper waters and an a p p a r e n t l y healthy diatom p o p u l a t i o n at deeper l e v e l s . U n l i k e June, the two areas were not dominated by a background assemblage of common st r a t i f i e d - c o m m u n i t y s p e c i e s , but e x h i b i t e d t h e i r own p o p u l a t i o n s w h i l s t f o l l o w i n g s i m i l a r e c o l o g i c a l s t r a t e g i e s . Both areas had upper water f l a g e l l a t e p o p u l a t i o n s and deeper diatom p o p u l a t i o n s , but s p e c i e s compositions were d i f f e r e n t between the a r e a s . 89 TABLE 14 Species C o r r e l a t i o n s with P r i n c i p a l Components N.Str.Georgia and Malaspina, August,1986 Code Species PCI PCII PCI 11 PCIV PCV 1 Actund 0. 15 -0.21 0.65* -0.24 0.12 2 Alexan 0.08 -0.64* -0.38* 0.28 0.04 3 Amphid -0.15 -0.07 0.31 -0.29 -0.09 4 A s t g l a 0.75* 0.40* -0.09 0.08 0.06 5 C e r a t i 0.27 -0.64* -0.01 -0.13 -0.43* 6 Chacnv 0.37* 0.50* -0.39* -0.27 -0.16 7 Chacom 0.58* 0.01 -0.07 0.09 0.19 8 Chacst 0.72* 0.21 -0.04 -0.07 0.12 9 Chadeb 0.79* 0.30 -0.20 -0.00 0.05 10 Chadec 0.61* -0.02 -0.14 0.27 0.27 1 1 Chaeib 0.32* -0.13 0.33* 0.33* 0.41* 12 Chaeto 0.41* 0.09 0.20 0.03 0.02 13 Chalac 0.70* 0.26 -0.13 0.21 0.25 14 Chasoc 0.76* 0.32* -0.20 0.19 -0.03 15 Choano 0.25 0.06 0.31 -0.10 0.08 16 Chryso 0.44* -0.56* -0.21 -0.17 -0.09 17 C i l i a t 0.11 -0.07 -0.44* 0.03 -0.18 18 Co s c i n 0.59* 0.01 0.13 -0.19 -0.15 19 Coswai 0.20 -0.42* -0.29 -0.52* 0.29 20 Crypto 0.33* -0.22 -0.05 -0.19 -0.28 21 C y l i n d 0.78* 0.30 0.05 -0.10 0.01 22 Detpum 0.22 -0.49* 0.24 -0.20 0.17 23 D i c r a t 0.25 0.01 0.16 0.03 -0.37* 24 Dicspe 0.34* -0.45* -0.05 -0.07 -0.52* 25 Dinoph 0.36* -0.10 -0.51* 0. 14 0.26 26 D i p l o p 0.1 7 0.05 -0.35* 0.07 -0.26 27 D i t b r i 0.64* -0.20 0.10 0.14 -0.12 28 Euczoo 0.74* 0.01 -0.18 0.16 0.07 29 Glenod 0.04 -0.34* -0.16 -0.49* 0.18 30 Gonyau 0.23 -0.14 -0.34* -0.36* -0.03 31 Gymnod -0.13 -0.37* -0.39* 0.08 0.32* 32 Gyrodi 0.17 0.12 -0.26 -0.29 0.13 * S i g n i f i c a n t at the 2.5% c r i t i c a l l e v e l 90 TABLE 14 (Cont'd) Species Corre la t ions with P r i n c i p a l Components N .Str .Georg ia and Malaspina, August,1986 Code Spec ies PCI PCII PCIII PCIV PCV 33 Hetaka 0.02 -0.23 -0.34* 0.49* 0.00 34 Hetmas 0.44* -0.21 -0.10 -0.17 -0.21 35 Leptoc 0.54* -0.40* 0.25 0.11 -0.02 36 Mesrub 0.13 -0.18 -0.25 -0.55* 0.24 37 Microf 0.25 -0.55* 0.08 0.27 -0.02 38 Microm 0.39* -0.51* -0.09 -0.17 0.03 39 Navicu 0.42* 0.45* 0.24 -0.08 -0.05 40 Nitpac 0.85* 0.02 -0.03 -0.01 -0.08 41 Nitzsc 0.72* 0.53* -0.04 0.08 0.03 42 Ochrom 0 . 1 8 0.01 -0.39* -0.02 -0.50* 43 Pennat 0.70* 0.43* 0.11 -0.10 0.06 44 Pleuro 0.33* -0.06 0.14 -0.54* 0.00 45 Progrc 0.15 -0.29 -0.53* 0.13 0.12 46 Protop 0.56* -0.20 -0.15 0.01 -0.02 47 Rhidel 0.08 -0.54* 0.02 0.30 -0.05 48 Rhi fra 0.55* -0.08 -0.21 0.02 -0.12 49 Rhiset 0.20 -0.57* 0.41* 0.24 0.05 50 Scripp 0.01 -0.31 -0.70* -0.01 0. 14 51 Skecos 0.76* 0.24 -0.27 0.16 -0.02 52 Stetur 0.45* 0.32* -0.04 0.23 -0.30 53 Tetras 0.27 -0.54* -0.13 0.10 -0.19 54 Thaaes 0.39* 0.07 0.62* -0.06 0.11 55 Thaags 0.09 -0.45* 0.53* -0.13 0.07 56 Thaang 0.28 -0.23 0.20 -0.37* -0.24 57 Thaecc 0.46* 0.05 0.07 -0.40* -0.21 58 Thafra 0.39* 0.20 0.50* 0.19 -0.24 59 Thanit 0.27 0.02 0.40* 0.27 0.03 60 Thanor 0.23 0.14 0.14 -0.21 0.18 61 Tharot 0.71* -0.31 0.04 0.01 -0.05 62 Trolep 0.41* 0.48* 0.01 0.07 -0.01 63 Zoofla 0.27 -0.43* 0.37* 0.09 0.18 * S i g n i f i c a n t at the 2.5% c r i t i c a l l e v e l 91 TABLE 15 Corre la t ions with Canonical Var iates N . S t r . Georgia and Malaspina Complex August 12-13 Canonical Var iate v1 v2 v3 v4 Comm C o r r e l . C o e f f . ( R ) 0 .40 0. 34 0. 29 0. 22 R-squared 0 .16 0. 12 0. 08 0. 05 Envi ronment Locat ion 0 .00 0. 95 -0 . 05 0. 26 0.97 Depth 0 .91 0. 09 0. 05 -0 . 26 0.91 Temperature -0 .99 0. 06 0. 04 0. 08 0.99 S a l i n i t y 0 .88 -o. 23 0. 35 0. 22 1 .00 Ni tra te 0 .83 0. 1 1 0. 37 -o. 37 0.99 Variance extracted 0 .66 0. 20 0. 05 0. 07 0.98 Phytoplankton Pr in Comp I -0 .00 -0 . 1 2 -0 . 37 0. 39 0.30 Pr in Comp II 0 .65 -o. 44 0. 20 0. 05 0.66 Pr in Comp III 0 .57 0. 50 -o. 06 0. 05 0.58 P r i n Comp IV -0 .21 0. 1 2 0. 48 0. 28 0.37 Pr in Comp V 0 .08 0. 32 0. 05 0. 03 0 .11 Redundancy 0 .13 0. 07 0. 03 0. 01 0.24 92 F i g u r e 9. S p e c i e s C o r r e l a t i o n s w i t h P C ' s I I & I I I NSG vs MC, August 12-13, 1986. Environmental c o r r e l a t i o n s w i t h each component are d e f i n e d . +'ve - NSG, Deep -'ve - MC. Surface Actund Thaags \ Rhlset \ V Zoof l a \ \ \ Chaelb Microf wndei mrzrr:* Ceratl - ; •leaps————: Microm Tetraa " " " - s r " ^ ^ 61anod _r \\ 0m / / / / ? I * . Coawai ' , / / ii t v HBtBKB B o n y a u / l D l p l o p _ Alexan eymnod / / /,Ochrom / / Cil iat / / ' / / Dlnoph Progrc Navicu ^ . -* Pennat =^=— Trolep „ ~ Nitzac """~~Astgla v. Chasoc Chacnv / / I / Scripp _L _L v u 0 «-a c o 3 o on a . to U CD z z o > -0.6 -0.4 -0.2 0.0 0.2 C o r r e l a t i o n w i t h PCII 0.4 93 3.K5.2 Northern S t r a i t of Georgia The dominants of t h i s r e g i o n have completely s h i f t e d to diatom s p e c i e s : Chaetoceros compressus (18%), Ch. d e b i l i s (15%), Skeletonema costatum (11%), and R h i z o s o l e n i a f r a g i l i s s i m a ( 6 % ) . To reduce the o r i g i n a l 87 s p e c i e s to fewer than 48, those s p e c i e s o c c u r r i n g i n l e s s than 45% of the samples were excluded. T h i s r e s u l t e d i n 47 r e t a i n e d s p e c i e s f o r the PCA which c o l l a p s e d 55% of the i n f o r m a t i o n i n t o 5 p r i n c i p a l components. The c o r r e l a t i o n s t r u c t u r e i s shown i n Table 16 and the c a n o n i c a l s t r u c t u r e i n Table 17. The f i r s t three c a n o n i c a l v a r i a t e s are r e t a i n e d , c o l l e c t i v e l y e x t r a c t i n g 82% of the environmental v a r i a n c e while e x p l a i n i n g 9.0%, 6.0%, and 5.4% of the b i o l o g i c a l v a r i a n c e each. Fi g u r e 10 presents s p e c i e s c o r r e l a t i o n s with depth and l o c a t i o n . PCI i s n e g a t i v e l y c o r r e l a t e d with CVIII (-0.67) and only c o r r e l a t e d s i g n i f i c a n t l y i n a negative f a s h i o n with s p e c i e s . CVIII t h e r e f o r e s i g n i f i e s an i n c r e a s e i n these s p e c i e s as one goes north and a s l i g h t i n c r e a s e as one heads e a s t . Accompanying these d i r e c t i o n v e c t o r s i s a decrease i n temperature and n i t r a t e . The s p e c i e s most c o r r e l a t e d with t h i s t r e n d are Ch. d e b i l i s (-0.91), Ch. s o c i a l i s ( - 0 . 9 1 ) , N i t z s c h i a spp. (-0.88), A. g l a c i a l i s (-0.86), N. p a c i f i c a (-0.85), and C y l i n d r o t h e c a (-0.83). In g e n e r a l , PCI d e s c r i b e s the northern bloom of diatoms c h a r a c t e r i s e d by the Chaetoceros s p e c i e s . .PCII i s n e g a t i v e l y c o r r e l a t e d with CVI (-0.79) so that p o s i t i v e l y c o r r e l a t e d s p e c i e s , Ch. e i b e n i i (0.38), Thalassionema  n i t z s c h i o i d e s (0.38), and T. f r a u e n f e l d i i (0.37) are f a v o u r i n g 94 the western s i d e , with a tendency towards the north, i n deep waters where the temperature i s low, the s a l i n i t y h igh, and the n i t r a t e h i g h . T h i s group of th r e e diatoms i s a l s o p a r t of the much l a r g e r bloom i n the no r t h . N e g a t i v e l y c o r r e l a t e d s p e c i e s such as Ceratium (-0.71), Ochromonas (-0.63), A. o s t e n f e l d i i (-0.60), Chrysochromulina (-0.55), and Dictyocha speculum (-0.55) are a l l m o t i l e and found more along the eastern s i d e , with a tendency to the south, i n s u r f a c e waters of high temperatures, low s a l i n i t i e s , and low n i t r a t e s . PCIII i s p o s i t i v e l y c o r r e l a t e d with CVII (0.71) which shows a strong west si d e tendency, with s u r f a c e waters that are warm and n i t r a t e reduced. Species f a v o u r i n g t h i s regime are Stephanopyxis t u r r i s (0.61), Dinophysis (0.48), A. o s t e n f e l d i i (0.47), Ch. e i b e n i i (0.46), and T. n i t z s c h i o i d e s (0.38). The l a t t e r two diatoms are a l s o found deeper i n these waters whereas T. f r a u e n f e l d i i remains i n the deeper l a y e r s . The n e g a t i v e l y c o r r e l a t e d cryptomonads (-0.52) and Th. e c c e n t r i c a (-0.50) are found more on the east s i d e a t depth where temperatures are c o o l e r and n i t r a t e h i g h e r . The cryptophytes are a l s o found i n sur f a c e waters (see PCI). A l l s i g n i f i c a n t s p e c i e s c o r r e l a t i o n s with PCIV are negative so that P C I V s negative c o r r e l a t i o n with CVII (-0.21) i n d i c a t e s northern waters with an e a s t e r n tendency and s l i g h t l y lower temperatures and n i t r a t e s . Responding to these northern waters are M. rubrum (-0.62), gymnodinoids (-0.53), Ch. d e c i p i e n s (-0.37), and c h o a n o f l a g e l l a t e s (-0.33). PCV i s not accounted f o r i n any great d e t a i l , having an 95 i n t r a s e t communality of 1.3%. Along PCV Th. a e s t i v a l i s (0.43) f i n d s i t s e l f opposed to Ch. convolutus (-0.53), Gyrodinium (-0.47), and M. rubrum (-0.39). The August a n a l y s i s has r e s u l t e d i n r e t a i n e d v a r i a t e s which account f o r very l i t t l e of the north-south v a r i a t i o n (0.34) i n the environmental data, a f a c t r e f l e c t e d i n the b i o l o g i c a l a n a l y s i s . Other than the diatom biomass i n c r e a s e from south to no r t h , most of the e c o l o g i c a l i n f o r m a t i o n and v a r i a t i o n occurs along the east-west a x i s . There are two d i f f e r e n t s e t s of s t r a t i f i e d communities on e i t h e r s i d e of the s t r a i t . The west s i d e has s u r f a c e waters c h a r a c t e r i s e d by a few d i n o f l a g e l l a t e s and diatoms whereas i t s deeper waters have three diatoms s p e c i f i c to them. The east s i d e ' s s u r f a c e waters are f l a g e l l a t e dominated while i t s deeper waters are a mixture of diatoms and n a n o f l a g e l l a t e s . 96 TABLE 16 Species Corre la t ions with P r i n c i p a l Components Northern S t r a i t of Georgia, August,1986 Code Spec ies PCI PCII PCI 11 PCIV PCV 1 Alexan 0.11 -0.60* 0.47* -0.18 0.15 2 Amphid 0.00 0.03 -0.28 0.06 -0.29 3 Astg la -0.86* 0.05 0.01 -0.11 -0.10 4 C e r a t i -0.21 -0.71* -0.21 0.26 -0.13 5 Chacnv -0.30 -0.24 -0.18 -0.20 -0.53* 6 Chacom -0.55* -0.01 -0.04 -0.32 -0.03 7 Chacst -0.72* 0.05 -0.29 -0.11 0.22 8 Chadeb -0.91* 0.02 0.15 0.03 0.08 9 Chadec -0.55* 0.02 0.21 -0.37* -0.29 10 Chaeib -0.45* 0.38* 0.46* -0.21 -0.21 1 1 Chaeto -0.45* 0.14 -0.16 -0.01 0.21 12 Chalac -0.61* 0.26 0.23 -0.16 -0.15 13 Chasoc -0.91* -0.04 0.03 -0.01 0.00 14 Choano -0.46* 0.02 -0.24 -0.33 0.26 15 Chryso -0.25 -0.55* -0.15 -0.13 -0.25 16 C i l i a t -0.12 -0.47* -0.03 0.04 -0.11 17 Cose in -0.48* -0.08 0.07 0.23 0.06 18 Crypto 0.02 -0.39* -0.52* 0.16 -0.11 19 C y l i n d -0.83* 0.01 -0.13 -0.00 0.03 20 Dicrat -0.27 -0.11 0.27 0.31 -0.15 21 Dicspe -0.26 -0.55* -0.14 0.47* -0.21 22 Dinoph -0.08 -0.42* 0.48* -0.37* 0.13 23 Diplop -0.13 -0.27 0.31 0.15 -0.32 24 D i t b r i -0.62* -0.35 -0.17 0.01 0.30 25 Euczoo -0.70* -0.23 0.23 -0.25 0.11 26 Gymnod 0.32 -0.39* 0.19 -0.53* 0.36 27 Gyrodi -0.30 -0 . 10 -0.25 -0.27 -0.47* 28 Hetmas -0.36 -0.38* -0.02 0.05 -0.14 29 Leptoc -0.58* -0.17 0.04 0.09 0.22 30 Mesrub 0.14 -0.26 -0.29 -0.62* -0.39* 31 Microm -0.19 -0.41* -0.23 -0.17 -0.04 32 Navicu -0.56* 0.26 -0.12 -0.08 -0.22 33 Nitpac -0.85* -0.14 0.03 0.04 0.08 34 Nitzsc -0.88* 0.23 -0.08 -0.00 0.03 35 Ochrom 0.03 -0.63* 0.32 0.36 0.10 36 Pennat -0.81* 0.08 -0 . 14 -0.07 -0.11 37 Pleuro -0.31 -0.35 -0.29 -0.11 0.29 38 Protop -0.48* -0.32 0.30 -0.03 -0.13 39 Rhi fra -0.31 -0.28 0.02 0.06 0.05 40 Rhiset -0.46* -0.13 0.14 0.01 0.07 41 Skecos -0.85* -0.31 0.08 -0.07 0.15 42 Stetur -0.43* 0.03 0.61* 0.33 -0.17 43 Thaaes -0.58* 0.32 -0.18 0.15 0.43* 44 Thaecc -0.31 -0.27 -0.50* 0.08 -0.06 45 Thafra -0.62* 0.37* 0.04 0.34 -0.06 46 Thanit -0.40* 0.38* 0.38* 0.27 -0.03 47 Tharot -0.61* -0.25 -0.13 -0.03 0.03 * S i g n i f i c a n t at the 2.5% c r i t i c a l l e v e l 97 TABLE 17 Corre la t ions with Canonical Var iates Northern S t r a i t of Georgia August 12-13 Canonical Var ia te v1 v2 v3 Comm C o r r e l . C o e f f . ( R ) 0 .37 0. 33 0. 32 R-sguared 0 . 1 3 o. 1 1 0. 10 Environment Transect -0 .27 0. 1 1 0. 50 0.34 Stat ion 0 .47 -o. 76 0. 18 0.82 Depth -0 .83 -o. 45 0. 07 0.90 Temperature 0 .91 0. 27 -0 . 18 0.93 S a l i n i t y -0 .99 0. 04 - 0 . 08 0.99 Ni trate -0 .83 -0 . 47 -0 . 20 0.95 Variance extracted 0 .58 0. 18 0. 06 0.82 Phytoplankton Pr in Comp I 0 . 1 7 -o. 1 5 -0 . 67 0.49 Pr in Comp II -0 .79 0. 03 -0 . 1 3 0.65 Prin Comp III 0 .07 0. 71 -0 . 10 0.52 Pr in Comp IV -0 .07 0. 10 -0 . 21 0.06 Pr in Comp V -0 .08 -o. 09 0. 01 0.01 Redundancy 0 .09 0. 06 0. 05 0.20 98 F i g u r e 10. S p e c i e s C o r r e l a t i o n s w i t h P C ' s I I £ I I I N.Str.Georgia. August 12-13. 1986. Environmental c o r r e l a t i o n s w i t h each component are d e f i n e d . +'ve - Nor thwest , Deep - * v e - S o u t h e a s t . S u r f a c e to o M M O CL x: f-l o S t e t u r A l e x a n s. Ochrom cw Dinoph \ Gymnod c o •«-» o ro ° r-i 0) c k w o o I Chae ib / I T h a n l t i / ' T h a f r a * tmas « CD o 0 «-c 3 CO •u CD CO C e r a t l O i c s p e ^ Cn ry so He  C l l i a t Microra ^ /<' '// co o '-0. _L c r y p t o ^ B B C C I L a CD CO •a ±i to a IU > "i -0.6 -0.4 -0.2 0.0 C o r r e l a t i o n w i t h PCII 0.2 0.4 99 3.K6 September , 1 986 3. J_. 6. J_ N. S t r a i t of Georgia vs Malaspina Complex Once again the phytoplankton were reduced down to f i v e p r i n c i p a l components c o n t a i n i n g 57% of the phytoplankton's v a r i a n c e . The s p e c i e s found were not q u i t e as u b i q u i t o u s as i n August; however, only those s p e c i e s that o c c u r r e d i n 20% or more of the samples were used i n the PCA. Table 18 presents the PCA's c o r r e l a t i o n s t r u c t u r e and Table 19 p r e s e n t s the c a n o n i c a l s t r u c t u r e of the CCA of the above f i v e p r i n c i p a l components with l o c a t i o n , depth, temperature, s a l i n i t y , and n i t r a t e . The f i r s t two c a n o n i c a l v a r i a t e s are r e t a i n e d , together e x t r a c t i n g 78.8% of the environmental v a r i a n c e and s e p a r a t e l y e x p l a i n i n g 13.1% and 4.9% of the b i o l o g i c a l v a r i a n c e , r e s p e c t i v e l y . S a l i n i t y does not p l a y a major r o l e i n t h i s c a n o n i c a l model, as witnessed by i t s very low i n t e r s e t communality (0.23). F i g u r e 11 presents s p e c i e s c o r r e l a t i o n s with depth and l o c a t i o n . The f i r s t PC i s almost e n t i r e l y p o s i t i v e l y c o r r e l a t e d with s p e c i e s and r e f l e c t s g eneral biomass. CVI i s a f f e c t i n g t h i s component the most (0.37) and i s a s u r f a c e water v a r i a t e with warm temperatures, reduced s a l i n i t y , and low n i t r a t e . There i s a l s o a vague l o c a t i o n element (0.39) which i n d i c a t e s a trend towards the MC and northern NSG. The l o c a t i o n , however, cannot be too important to t h i s v a r i a t e because at the time of sampling, the NSG had by f a r the g r e a t e r biomass of the two r e g i o n s . The most h i g h l y c o r r e l a t e d s p e c i e s with PCI are m i s c e l l a n e o u s pennate diatoms (0.87), N i t z s c h i a (0.87), Chaetoceros compressus (0.86), Ch. s o c i a l i s (0.85), and 100 C y l i n d r o t h e c a (0.84). PCII i s h i g h l y n e g a t i v e l y c o r r e l a t e d with CVI which suggests waters below or at the p y c n o c l i n e . Species found here are n e a r l y a l l diatoms i n c l u d i n g Ch. convolutus (0.56), Thalassionema n i t z s c h i o i d e s (0.50), Eucampia zoodiacus (0.49), T h a l a s s i o s i r a r o t u l a (0.49), T h a l a s s i o t h r i x f r a u e n f e l d i i (0.47), and N i t z s c h i a p a c i f i c a (0.45). The only exceptions are c o l o u r l e s s s p e c i e s of Amphidinium (0.60) such as A. sphenoides and A. stigmatum. Species n e g a t i v e l y c o r r e l a t e d with PCII w i l l be p o s i t i v e l y c o r r e l a t e d with CVI and are thus found i n s u r f a c e waters. The s t r o n g e s t c o r r e l a t i o n s are with N o c t i l u c a  s c i n t i l l a n s (-0.69), Mesodinium rubrum (-0.65), Chrysochromulina (-0.65), Micromonas p u s i l l a (-0.59), T e t r a s e l m i s (-0.57), and Heteromastix (-0.51). N o c t i l u c a and p h o t o s y n t h e t i c c i l i a t e s are more important to the MC while the n a n o f l a g e l l a t e s are found i n both a r e a s . Nearly a l l the s i g n i f i c a n t negative c o r r e l a t i o n s are with f l a g e l l a t e d forms, a f a c t not too s u r p r i s i n g as PCII i s much more s t r o n g l y c o r r e l a t e d with the s t r o n g l y s u r f a c e - s t r a t i f i e d CVI (-0.81) than i s PCI (0.37). PCIII i s most c o r r e l a t e d with CVII (-0.63) which i s l a r g e l y l o c a t i o n o r i e n t e d (-0.87), probably r e p r e s e n t i n g the NSG. T h i s v a r i a t e a l s o denotes upper waters, warm temperatures and lower n i t r a t e . As CVII i s n e g a t i v e l y c o r r e l a t e d with PCIII, the v a r i a t e as d e s c r i b e d w i l l c h a r a c t e r i s e a l l those s p e c i e s n e g a t i v e l y c o r r e l a t e d with PCIII. These s p e c i e s are Protogonyaulax c a t e n e l l a (-0.61), Alexandrium o s t e n f e l d i i (-0.46), d i p l o p s a l o i d s (-0.38), O d o n t e l l a l o n q i c r u r i s (-0.34), 101 and E u t r e p t i e l l a (-0.34). I t i s i n t e r e s t i n g to note that these s p e c i e s are only responding to temperature r a t h e r than s a l i n i t y . The p o s i t i v e l y c o r r e l a t e d s p e c i e s must be more i n d i c a t i v e of the MC, probably at depth. The more h i g h l y c o r r e l a t e d organisms are Th. a n g s t i i (0.74), Actinoptychus undulatus (0.62), R h i z o s o l e n i a sp. (0.61), c h o a n o f l a g e l l a t e s (0.55), Th. n o r d e n s k i o e l d i i (0.56), and Skeletonema costatum (0.52). The v a r i a n c e of PCIV i s l e a s t e x p l a i n e d by the two c a n o n i c a l v a r i a t e s r e t a i n e d , having an i n t r a s e t communality of 1%. N e i t h e r CVI nor CVII are c o n t r i b u t i n g any i n f o r m a t i o n . Along PCIV the s p e c i e s s i g n i f i c a n t l y n e g a t i v e l y c o r r e l a t e d are Stephanopyxis t u r r i s (-0.52), A. undulatus (-0.45), 0. l o n g i c r u r i s (-0.38), Gyrodinium (-0.38), and N. s c i n t i l l a n s (-0.36). The p o s i t i v e l y c o r r e l a t e d s p e c i e s are Ch. l a c i n i o s u s (0.45), S. costatum (0.37), and m i s c e l l a n e o u s n a n o f l a g e l l a t e s (0.35). I t seems that the negative c o r r e l a t i o n s are with l a r g e d i n o f l a g e l l a t e s and l a r g e diatoms which u s u a l l y do not form c h a i n s . The p o s i t i v e l y c o r r e l a t e d s p e c i e s are much sm a l l e r and the diatoms are chain-formers. PCV i s most a f f e c t e d by CVII (-0.31), the l o c a t i o n v a r i a t e . The negative c o r r e l a t i o n , as above, i s d e s c r i b i n g the deeper waters of the MC. In t h i s component, however, only the group of u n i d e n t i f i e d thecate d i n o f l a g e l l a t e s (0.50) i s a s s o c i a t e d . The n e g a t i v e l y c o r r e l a t e d s p e c i e s are Dictyocha speculum (-0.59), Amphidinium (-0.53), R h i z o s o l e n i a f r a g i l i s s i m a (-0.46), mi s c e l l a n e o u s n a n o f l a g e l l a t e s (-0.36), and T e t r a s e l m i s (-0.34). PCV has p i c k e d out a d i f f e r e n t set of opposing s p e c i e s than has 102 PCIII. Presumably, the above negative species are part of the NSG's upper waters, maybe located in a di f f e r e n t section of t h i s area. The only possible discrepancy i s with Amphidinium, which was found e a r l i e r to be in NSG's deeper waters and i s found here in NSG's surface waters. Perhaps the category "Amphidinium" contains a number of species so that these opposing trends may be due to two separate species populations. As in August, the analysis has i d e n t i f i e d two s t r a t i f i e d regimes with their own populations of surface and deeper water species. It seems as though species s t r a t i f i c a t i o n by depth has become s l i g h t l y less important or defined and that location has become an important influence once again for both species abundance and composition. 103 TABLE 18 Species Corre la t ions with P r i n c i p a l Components N .Str .Georg ia and Malaspina, September,1986 Code Species PCI PCII PCIII PCIV PCV 1 Actund 0.13 -0.05 0.62* -0.45 0.07 2 Alexan 0.60* -0.28 -0.46* 0.03 0.26 3 Amph i d 0.13 0.60* 0 . 1 9 -0.04 -0.53* 4 Astg la 0.74* 0.30 -0.05 -0.13 -0.05 5 Bidlon 0.64* 0.28 -0.34* -0.38* 0.09 6 Centr i 0.29 0.30 0.01 -0.08 0.24 7 C e r a t i 0.13 -0.16 0.32* -0.27 0.10 8 Chacnv 0.09 0.56* 0.02 -0.18 0.16 9 Chacom 0.86* 0.18 -0.16 0.26 -0.03 10 Chacst 0.36* 0.02 -0.02 0.28 0.10 1 1 Chadeb 0.75* 0.28 -0.12 -0.10 -0.11 12 Chadec 0.76* -0.11 -0.09 -0.03 0.21 13 Chaeib 0.16 0.41* -0.05 -0.10 -0.16 14 Chaeto 0.76* 0.28 -0.20 -0.07 -0.07 15 Chalac 0.48* -0.05 0.24 0.45* -0.03 16 Chasoc 0.85* -0.02 -0.10 -0.18 -0.01 1 7 Choano 0.05 -0.24 0.55* 0.08 0.00 18 Chryso 0.12 -0.65* 0.11 0.28 -0.18 19 C i l i a t 0.50* -0.28 -0.08 0.28 -0.21 20 Cose in 0.07 0.10 0.49* -0.30 -0.07 21 Crypto 0.20 -0.42* 0.13 0.20 -0.19 22 C y l i n d 0.84* 0.20 0.08 0.01 0.09 23 Dicrat -0.03 -0.34* -0.22 0.25 -0.11 24 Dicspe 0.49* -0.07 -0.14 -0.16 -0.59* 25 Dinoph 0.42* 0.08 -0.02 0.25 0.19 26 Diplop 0.52* -0.02 -0.38* -0.09 0.03 27 D i t b r i 0.73* 0.17 0.22 0.06 0.20 28 Euczoo 0.64* 0.49* -0.02 -0.26 -0.11 29 Eutrep 0.37* -0.22 -0.34* 0.24 0.02 30 Glenod 0.41* -0.26 0.01 -0.15 0.50* * S i g n i f i c a n t at the 2.5% c r i t i c a l l e v e l 104 TABLE 18 (Cont'd) Species C o r r e l a t i o n s with P r i n c i p a l Components N.Str.Georgia and Malaspina, September,1986 Code Species PCI PCII PCI 11 PCIV PCV 31 Gymnod 0.48* -0.47* 0.10 -0.09 0.17 32 Gyrodi 0.47* -0.12 -0.20 -0.38* -0.02 33 Hetaka 0.68* -0.29* -0.31 0.22 -0.01 34 Hetmas -0.06 -0.51* 0.03 0.31 -0.10 35 Leptoc 0.45* -0.05 0.25 -0.15 -0.02 36 Mesrub 0.28 -0.65* 0.32* -0.18 -0.08 37 Mic r o f 0.18 -0.40* 0.25 0.35* -0.36* 38 Microm 0.05 -0.59* 0.08 0.31 -0.23 39 Navicu 0.43* 0.22 0.16 -0.28 -0.01 40 Nitpac 0.66* 0.45* 0.11 -0.14 0.06 41 N i t z s c 0.87* 0.11 0.13 0.05 -0.04 42 Nocsci 0.10 -0.69* -0.01 -0.36* 0.16 43 Pennat 0.87* 0.02 0.01 0.18 0.05 44 Pleuro 0.14 0.35* 0.17 -0.12 0.02 45 Procat 0.36* -0.20 -0.61* -0.12 0.05 46 Protop 0.54* -0.43* 0.16 -0.21 0.07 47 R h i d e l 0.44* 0.13 -0.04 -0.26 -0.26 48 Rhi f r a 0.47* -0.23 0.02 -0.09 -0.46* 49 Rhiset 0.69* -0.38* -0.03 -0.25 0.05 50 Rhizos 0.22 -0.51* 0.61* 0.08 0. 1 1 51 Skecos 0.43* 0.12 0.52* 0 .37* 0.29 52 St e t u r -0.06 -0.05 0.21 -0.52* -0.17 53 T e t r a s 0.51* -0.57* 0.03 0.07 -0.34* 54 Thaaes 0.14 -0.11 0.33* -0.08 0.05 55 Thaags 0.34* -0.18 0.74* -0.14 0.09 56 Thaecc 0.11 0.02 0.22 0.14 0.23 57 Thafra 0.38* 0.47* 0.43* 0.08 0.11 58 Than i t 0.53* 0.50* 0.10 0.10 0.00 59 Thanor 0.53* 0.25 0.54* 0.32* -0.06 60 Tharot 0.49* 0.49* 0.33* 0.24 -0.01 61 Zo o f l a 0.33* -0.32* -0.31 0.25 -0.02 * S i g n i f i c a n t a t the 2.5% c r i t i c a l l e v e l 105 TABLE 19 C o r r e l a t i o n s with C a n o n i c a l V a r i a t e s N.Str. Georgia and Malaspina Complex September 16-17 Canonical V a r i a t e v i v2 Comm C o r r e l . C o e f f . ( R ) 0. 40 0 .32 R-squared 0. 16 0 .10 Environment Locat ion 0. 39 -0 .87 0.91 Depth -0. 84 -0 .40 0.92 Temperature 0. 75 0 .48 0.78 S a l i n i t y -0. 69 0 .02 0.23 N i t r a t e -0. 88 -0 .36 0.91 Variance e x t r a c t e d 0. 53 0 .26 0.79 Phytoplankton P r i n Comp I 0. 37 0 .00 0.14 P r i n Comp II -0. 81 0 .02 0.66 P r i n Comp I I I -0. 03 -0 .63 0.40 P r i n Comp IV 0. 10 0 .00 0.01 P r i n Comp V 0. 01 -0 .31 0.10 Redundancy 0. 13 0 .05 0.18 106 F i g u r e 11. S p e c i e s C o r r e l a t i o n s w i t h P C ' s I I S I I I NSG vs MC, September 16-17. 1986. Environmental c o r r e l a t i o n s w i t h each component are d e f i n e d . CO d to d +'ve - NSG deep - ' v e - MC s u r f a c e cu M M M CJ Q. x: 4J * O c d o f-f •U ID cu i - l C o CJ «r d I co d I R h i z o s \ \ Thaags \ \ \ Ac tund Choano \ \ Mesrub Chry so * \ i \ i i \ Thaaes ^ v ^ M i c r o f P r o t o p * * . Skecos Cosc ' ln / " / '' / Thanor T h a f r a / T h a r o t / / y ^ p i e u r o • „ , Amph i d s ^ p i e u r o ^ • ^ 1 , N l t p a c ^ ^ r : - - T h a n i t Chacnv Euczoo Chae ib co o a »-a c CO 3 CD CO CD CJ to z z CD CD > > B i d l o n o '-O.B -L _L -0.6 - 0 . 4 -0.2 0.0 0.2 0 . 4 C o r r e l a t i o n w i t h PCII 0.6 o.a 107 3.K6.2 Northern S t r a i t of Georgia In September, the northern S t r a i t was dominated by a s o l e diatom s p e c i e s , R h i z o s o l e n i a s e t i g e r a (39%). Chaetoceros  compressus (9%) i s s t i l l a major c o n t r i b u t o r and we see what must be recognised as the NSG's s t a b l e background dominants: Chrysochromulina (13%), c i l i a t e s (11%), and cryptomonads ( 8 % ) . I t should be remembered that these l a t t e r three groups c o n s i s t of more than one s p e c i e s and t h i s may a l t e r how one views s p e c i e s c o n t r i b u t i o n s to biomass. The o r i g i n a l 82 s p e c i e s groups were reduced to 48 by e x c l u d i n g those which o c c u r r e d i n l e s s than 35% of the samples. These 48 were used i n a PCA which condensed 64% of the i n f o r m a t i o n i n t o 5 p r i n c i p a l components which were then used i n a CCA with the environmental v a r i a b l e s t r a n s e c t , s t a t i o n , depth, temperature, s a l i n i t y , and n i t r a t e . The c o r r e l a t i o n s t r u c t u r e i s shown i n Table 20 and the c a n o n i c a l s t r u c t u r e i n Table 21. The f i r s t three v a r i a t e s are r e t a i n e d , together e x t r a c t i n g 85.0% of the environmental v a r i a n c e and i n d i v i d u a l l y e x p l a i n i n g 12.6%, 7.3%, and 4.9% of the b i o l o g i c a l v a r i a n c e , r e s p e c t i v e l y . N o t i c e that s a l i n i t y i s the l e a s t e x p l a i n e d (0.61) p h y s i c a l parameter by the r e t a i n e d v a r i a t e s . F i g u r e 12 p r e s e n t s s p e c i e s c o r r e l a t i o n s with depth and l o c a t i o n . The only s i g n i f i c a n t s p e c i e s c o r r e l a t i o n s with PCI are p o s i t i v e , and there are many of them. PCI i s a l s o c o r r e l a t e d with three c a n o n i c a l v a r i a t e s d e s c r i b i n g separate regimes, t h e r e f o r e , t h i s p r i n c i p a l component must be a g e n e r a l biomass one. The f i r s t c a n o n i c a l v a r i a t e CVI (-0.53) i s one d e s c r i b i n g s t r a t i f i c a t i o n with a strong s u r f a c e o r i e n t a t i o n and i t s 108 attendant t e m p e r a t u r e - s a l i n i t y - n i t r a t e p a t t e r n . The area i s app a r e n t l y i n the northwest. CVII (-0.43) d e s c r i b e s northern or no r t h e a s t e r n waters. There i s a l s o a tendency towards depth with decreased temperatures and s a l i n i t i e s and i n c r e a s e d n i t r a t e s . CVIII (-0.30) i s a strong west s i d e v a r i a t e and focuses i n on deeper waters with the expected t e m p e r a t u r e - s a l i n i t y - n i t r a t e p a t t e r n s . From these three areas comes the bulk of the NSG's biomass. The most h i g h l y c o r r e l a t e d s p e c i e s are mi s c e l l a n e o u s pennate diatoms (0.91), N i t z s c h i a spp. (0.90), Ch. compressus (0.89), C y l i n d r o t h e c a (0.89), Ch. s o c i a l i s (0.87), and Ch. d e b i l i s (0.80), a p a t t e r n very s i m i l a r to the CCA on the f i v e PC's c o n t a i n i n g the two region's data, c o n f i r m i n g the higher biomass contained w i t h i n the NSG. PCII has narrowed the view i n that the major c o r r e l a t i o n i s with CVI (-0.71) the NW upper, s t r a t i f i e d waters. A l s o c o n t r i b u t i n g i s a p o s i t i v e c o r r e l a t i o n with CVII (0.36) i n d i c a t i n g upper waters i n the south and somewhat to the west where temperatures and s a l i n i t i e s are s l i g h t l y e l e v a t e d and n i t r a t e reduced. These upper waters are host to z o o f l a g e l l a t e s (0.58), A. o s t e n f e l d i i (0.53), D i c r a t e r i a (0.51), Heterosigma  akashiwo (0.50), Chrysochromulina (0.50), and cryptomonads (0.44). Negative s p e c i e s c o r r e l a t i o n s w i l l be with organisms found at depth, e s p e c i a l l y i n the SE and i n the north towards the e a s t . These s p e c i e s are T. f r a u e n f e l d i i (-0.76), Amphidinium (-0.69), Th. r o t u l a (-0.57), A. undulatus (-0.55), Ch. convolutus (-0.54), Th. n o r d e n s k i o e l d i i (-0.52), and T. n i t z s c h i o i d e s (-0.51). 109 Even more s p e c i f i c i s PCIII which i s n e g a t i v e l y c o r r e l a t e d with CVIII (-0.57) d e s c r i b i n g southern waters at depth with c o o l e r temperatures and higher s a l i n i t i e s and n i t r a t e s . The only s p e c i e s s i g n i f i c a n t l y c o r r e l a t e d with t h i s regime i s 0. l o n g i c r u r i s (0.47). A l t e r n a t e l y , northern s t r a t i f i e d s u r f a c e waters are populated by Chrysochromulina (-0.51), Micromonas  p u s i l l a (-0.51), cryptomonads (-0.50), Th. n o r d e n s k i o e l d i i (-0.50), and a R h i z o s o l e n i a sp. (-0.48). PCIV, c o r r e l a t e d to CVII (0.41), looks at upper southern and western waters and to a l e s s e r extent, western deeper waters (CVIII= -0.22). R. f r a q i l i s s i m a (0.50) and D. speculum (0.38) show a t r e n d with these western waters. U n i d e n t i f i e d thecate d i n o f l a g e l l a t e s (-0.55) and Dinophysis (-0.38) p r e f e r l e s s s a l i n e , n i t r a t e r e p l e t e n o r t h e a s t e r n waters as w e l l as ea s t e r n s u r f a c e waters. PCV i s the l e a s t e x p l a i n e d component by the c a n o n i c a l model, having an i n t r a s e t communality of 10.5%. N e v e r t h e l e s s , i t i s p o s i t i v e l y c o r r e l a t e d with CVI (0.32), the southwestern su r f a c e waters mentioned above, where Ceratium (0.54), D. speculum (0.45), and A. undulatus (0.38) f i n d themselves t o g e t h e r . T h i s a n a l y s i s has p o i n t e d out that there i s a l a r g e biomass group which i s not c o n f i n e d to any one part of the S t r a i t , nor to any p a r t i c u l a r regime. Most d i f f e r e n c e s appear to be on an east-west b a s i s as groups found i n the north are o f t e n found i n the south. Again we f i n d s u r f a c e - s t r a t i f i e d s p e c i e s as w e l l as a host of deeper water diatoms. 1 10 TABLE 20 Species Corre la t ions with P r i n c i p a l Components Northern S t r a i t of Georgia, September,1986 Code Species PCI PCII PCIII PCIV PCV 1 Actund 0.38* -0.55* 0.02 -0.06 0.38* 2 Alexan 0.56* 0.53* 0.30 -0.26 -0.20 3 Amph i d 0.07 -0.69* -0.32 0.21 0.23 4 Astg la 0.77* -0.22 0.05 0.02 0.11 5 Bidlon 0.71* -0.02 0.47* 0.15 0.05 6 Cerat i 0.16 -0.10 -0.01 -0.31 0.54* 7 Chacnv 0.03 -0.54* 0.32 -0.06 0.16 8 Chacom 0.89* 0.06 -0.21 -0.10 -0.12 9 Chadeb 0.80* -0.08 0.07 0.08 -0.13 10 Chadec 0.78* 0.14 0.17 -0.13 -0.08 1 1 Chaeto 0.76* -0.07 0.23 0.13 0.07 12 Chasoc 0.87* 0.13 0.15 0.23 0.07 13 Choano 0.18 -0.27 -0.40* -0.14 0.07 1 4 Chryso -0.04 0.50* -0.51* -0.04 0.12 15 C i l i a t 0.46* 0.36 -0.36 0.01 0.13 16 Cose in 0.09 -0.56* 0.25 0.26 -0.00 17 Crypto -0.10 0.44* -0.50* 0.10 0.06 18 C y l i n d 0.89* -0.19 0.10 0.06 -0.12 19 Dicrat -0.11 0.51* -0.41* 0.02 -0.09 20 Dicspe 0.49* 0.23 -0.33 0.38* 0.45* 21 Dinoph 0.29 0.06 0.00 -0.52* -0.17 22 D i t b r i 0.69* -0.31 0.03 -0.16 -0.13 23 Euczoo 0.63* -0.38* 0.27 0.28 -0.06 24 Eutrep 0.35 0.40* -0.03 0.04 -0.17 25 Glenod 0.48* 0.14 0.08 -0.55* 0.33 26 Gymnod 0.54* 0.30 0.09 -0.15 0.09 27 Gyrodi 0.67* 0.27 0.27 -0.03 0.02 28 Hetaka 0.63* 0.50* -0.13 -0.14 0.03 29 Hetmas -0.20 0.43* -0.33 -0.06 -0.04 30 Leptoc 0.52* -0.27 0.12 0.13 -0.09 31 Microf 0.20 0.13 -0.68* 0.15 -0.29 32 Microm -0.10 0.46* -0.51* 0.04 0.06 33 Navicu 0.49* -0.27 0.18 0.17 0.10 34 Nitpac 0.71* -0.44* 0.07 0.09 0.10 35 Nitzsc 0.90* -0.13 -0.05 -0.01 -0.11 36 Pennat 0.91* -0.01 -0.13 -0.04 -0.08 37 Protop 0.72* 0.20 -0.06 -0.17 0.27 38 Rhi fra 0.49* 0.17 -0.16 0.49* -0.32 39 Rhiset 0.80* 0.33 0.14 0.21 -0.00 40 Rhizos 0.45* -0.08 -0.48* -0.24 0.12 41 Skecos 0.43* -0.46* -0.19 -0.31 -0.36 42 Tetras 0.55* 0.40* -0.38* 0.17 0.24 43 Thaags 0.61* -0.47* -0.25 -0.04 -0.12 44 Thafra 0.34 -0.75* -0.07 -0.20 -0.13 45 Than i t 0.45* -0.51* 0.03 -0.08 -0.05 46 Thanor 0.47* -0.52* -0.50* -0.15 -0.15 47 Tharot 0.42* -0.57* -0.18 -0.12 0.12 48 Zoofla 0.22* 0.58* -0.16 -0.08 -0.01 * S ign i f i cant at the 2.5% c r i t i c a l l eve l 111 TABLE 21 Corre la t ions with Canonical Var iates Northern S t r a i t of Georgia September 16-17 Canonical Var ia te vi v2 v3 Comm C o r r e l . C o e f f . ( R ) 0. 40 0. 35 0. 31 R-squared 0. 16 0. 12 0. 10 Environment Transect -o. 23 -0 . 92 -o. 1 1 0.92 Stat ion 0. 29 -0 . 21 0. 93 0.99 Depth 0. 85 -0 . 16 -o. 23 0.80 Temperature -0 . 77 0. 19 0. 46 0.85 S a l i n i t y 0. 58 0. 21 -o. 48 0.61 Ni trate 0. 86 -0 . 30 -o. 32 0.93 Variance extracted 0. 42 0. 18 0. 24 0.84 Phytoplankton Pr in Comp I -0 . 53 -0 . 43 -o. 30 0.55 Pr in Comp II -0 . 71 0. 36 0. 17 0.66 Pr in Comp III 0. 04 0. 15 -0 . 57 0.35 Pr in Comp IV 0. 09 0. 41 -o. 22 0.22 Pr in Comp V -o. 06 0. 32 -o. 03 0.10 Redundancy 0. 13 0. 07 0. 05 0.25 112 F i g u r e 12. S p e c i e s C o r r e l a t i o n s w i t h P C ' s I I £ I I I N.Str.Georgia. September 16-17. 1986. Environmental c o r r e l a t i o n s w i t h each component are d e f i n e d . +'ve - No r thwes t s u r f a c e , Southwest more s a l i n e - * v e - S o u t h e a s t deep. N o r t h e a s t l e s s s a l i n e d H ~ M CJ GL 5 ° •r* o S C s » -P o (0 I l- l 0) c o B l d l o n • Chacnv C o s c i n A l e x a n T h a f r a to d t Amphid Thanor / 1 R h i z o a o '-0.8 J . \ V I V V M l c r o f V VNV Hetma8 T e t r a 8 V V\ D l c r a t c r y p t o t c h r y a o H i c rom -0.6 -0.4 -0.2 0.0 0.2 C o r r e l a t i o n w i t h PCII 0.4 113 3_.J_.7 C h l o r o p h y l l Maxima Biomass Dominants Canonical a n a l y s i s was performed on the c h l o r o p h y l l maxima biomass dominants, determined as those s p e c i e s accounting f o r g r e a t e r than 2% of the o v e r a l l carbon. The c h l o r o p h y l l maximum (and p y c n o c l i n e ) f o r each s t a t i o n was assumed to be separate from a l l others, though a d j o i n i n g s t a t i o n s may have been s h a r i n g the same maximum. C e r t a i n l y between the NSG and MC the maxima were d i f f e r e n t . The s t a t i s t i c s have not been presented because the number of cases for each month (16) i s not s u f f i c i e n t to j u s t i f y the use of CCA. However, g e n e r a l i t i e s from the a n a l y s i s h e l p e l u c i d a t e components of the system. The biomass dominants i n the NSG and MC's c h l o r o p h y l l maxima are presented i n Table 22 f o r the f i v e months. In March the c h l o r o p h y l l maxima i n the NSG were found mostly at the s u r f a c e , while p y c n o c l i n e s were deeper down. N i t r a t e remained hi g h . In the MC the c h l o r o p h y l l maxima were at the s u r f a c e , as were the p y c n o c l i n e s . N i t r a t e had been s i g n i f i c a n t l y reduced. I t appears that the depth of the p y c n o c l i n e was the major f a c t o r determining phytoplankton community s t r u c t u r e whereas n e i t h e r temperature nor s a l i n i t y g r a d i e n t s a f f e c t e d the systems s i g n i f i c a n t l y . In s u r f a c e waters of lower s a l i n i t y the c h l o r o p h y l l maxima were c h a r a c t e r i s e d by Gyrodinium, M. rubrum, c i l i a t e s , and Th. r o t u l a . A l s o , when s a l i n i t i e s were lower and temperatures higher, with no depth s p e c i f i c i t y , C. aureus, Ch. d e b i l i s , Th. e c c e n t r i c a , and Th. n o r d e n s k i o e l d i i predominated. When there was temperature and s a l i n i t y s t r a t i f i c a t i o n , Chrysochromulina, 1 14 cryptomonads, and Th. n o r d e n s k i o e l d i i were more abundant while M. rubrum and T e t r a s e l m i s seemed to p r e f e r more mixed regimes. In A p r i l the NSG s t i l l had deep water p y c n o c l i n e s and the c h l o r o p h y l l maxima were dominated by n a n o f l a g e l l a t e s . P y c n o c l i n e s i n the MC were shallow and the c h l o r o p h y l l maxima were c h a r a c t e r i s e d by l a r g e diatom s p e c i e s . N i t z s c h i a p a c i f i c a was very abundant i n n e a r - s u r f a c e c h l o r o p h y l l maxima i n the MC and a l s o appeared i n the deeper maxima of the n o r t h e a s t e r n NSG, suggesting i n t r u s i o n of t h i s diatom from the former r e g i o n . Gyrodinium p r e f e r r e d those NSG maxima c h a r a c t e r i s e d by warmer temperatures. In areas of low s a l i n i t y s t r a t i f i c a t i o n , Chaetoceros  e i b e n i i , Mesodinium rubrum, and Chrysochromulina predominated. Gyrodinium was a l s o found i n areas of i n c r e a s e d s a l i n i t y s t r a t i f i c a t i o n where p y c n o c l i n e s were deeper. By June the c h l o r o p h y l l maxima were dominated by m o t i l e forms i n both systems. In the more mixed areas, cryptomonads and Chrysochromulina dominated s u r f a c e c h l o r o p h y l l maxima. Mesodinium a l s o p r e f e r r e d low s t r a t i f i c a t i o n and was found i n maxima at a l l depths. In areas where temperature s t r a t i f i c a t i o n was high, c i l i a t e s , cryptomonads, Gyrodinium, P r o t o p e r i d i n i u m , and T e t r a s e l m i s dominated c h l o r o p h y l l maxima near the s u r f a c e . Near s u r f a c e maxima i n areas of s a l i n i t y s t r a t i f i c a t i o n were favoured by c i l i a t e s , cryptomonads, gymnodinoids, and T e t r a s e l m i s . In August there were two d i s t i n c t c h l o r o p h y l l maxima. Those at depth were dominated by the Chaetoceros s p e c i e s 115 Ch. compressus, Ch. d e b i l i s , Ch. l a c i n i o s u s , Ch. s o c i a l i s -- and Skeletonema costatum. Near-surface maxima were a s s o c i a t e d with warmer and l e s s s a l i n e waters, favoured by cryptomonads and Chrysochromulina. Most of the diatoms were a s s o c i a t e d with s a l i n i t y s t r a t i f i c a t i o n . Both temperature and s a l i n i t y s t r a t i f i c a t i o n were p r e f e r r e d by the n a n o f l a g e l l a t e s and Gyrodinium. The only s p e c i e s group responding s o l e l y to temperature s t r a t i f i c a t i o n was P r o t o p e r i d i n i u m , which seemed to favour warmer su r f a c e waters. T h i s group was not found a s s o c i a t e d with the subsurface diatom c o n c e n t r a t i o n s . September c h l o r o p h y l l maxima i n c l u d e d very l o c a l i s e d blooms of R h i z o s o l e n i a s e t i g e r a i n the western NSG and Mesodinium  rubrum i n the MC. Both organisms were a s s o c i a t e d with low l e v e l s of s t r a t i f i c a t i o n . A l s o a s s o c i a t e d with mixed regimes was T h a l a s s i o s i r a a n q s t i i , a l a r g e c e n t r i c diatom, and the prymnesiophyte Chrysochromulina. In areas of strong temperature and s a l i n i t y s t r a t i f i c a t i o n Chaetoceros compressus favoured deep c h l o r o p h y l l maxima. 116 TABLE 22. C h l o r o p h y l l Maxima Biomass Dominants. Species/groups comprising g r e a t e r than 2% of the c o l l e c t i v e c h l o r o p h y l l maxima's biomass. March Spec i e s %Biom Chadeb 7. 5 Chasoc 2. 0 Chryso 6. 1 C i l i a t 17. 4 Corymb 2. 6 Crypto 7. 4 Detpum 3. 1 Gyrodi 9. 5 Mesrub 3. 0 Thaaes 6. 3 Thaecc 19. 6 Thanor 3. 8 Tharot 3. 0 A p r i l Species %Biom B i d l o n 2 .0 Chacst 2 .5 Chadeb 6 .6 Chaeib 4 .7 Chryso 16 .2 C i l i a t 1 1 .4 Crypto 1 1 .0 Euczoo 7 . 1 Gyrodi 7 .0 Mesrub 3 .0 Nitpac 7 .8 R h i d e l 3 .4 June Spec i e s %Biom Chryso 4.5 C i l i a t 38.7 Crypto 7.1 Gymnod 3.6 Gyrodi 8.7 Hetaka 10.6 Mesrub 6.7 M i c r o f 2.0 Protop 2.1 T e t r a s 3.0 August September Species %Biom Species %Biom Chacom 16.4 Chacom 6.2 Chadeb 12.3 Chryso 11.8 Chalac 3.1 C i l i a t 9.2 Chasoc 4.4 Crypto 7.3 Chryso 6.0 Mesrub 17.5 C i l i a t 4.9 Rhiset 25.4 Crypto 2.9 Thaags 7.5 Gyrodi 2.3 Nitpac 2.3 Protop 2.3 R h i f r a 4.9 Skecos 9.5 Tharot 2.7 1 17 3.j_.8 CCA Summary Canonical c o r r e l a t i o n analysis i s a useful data summarisation method. It extracts trends, such as a temperature gradient across the S t r a i t , that one might overlook when simply s i f t i n g through the information by hand. The technique also saves presenting raw data within the t h e s i s . It was expected that species patterns could be predicted from temperature-salinity regimes; however, upon inclusion of depth and location dummy variables, the analysis was dominated by these factors and yielded the most information. Temperature and s a l i n i t y were most independent in these analyses during times of low s t r a t i f i c a t i o n . Once v e r t i c a l gradients were established, temperature, s a l i n i t y , and n i t r a t e patterns were extracted as components of s t r a t i f i c a t i o n without contributing much effect outside t h i s phenomenon. This analysis revealed that the greatest variation was due to biomass differences between areas or depths. In March and A p r i l the MC dominated the system with respect to biomass. In June biomass p a r t i t i o n i n g was depth related, surface waters supporting extensive populations of motile forms. Variation due to depth and s t r a t i f i c a t i o n characterised August and September, but location was also re-exerting a selection force. Because the f i r s t p r i n c i p a l component was extracting variation due to biomass, th i s component was often not especially related to any p a r t i c u l a r environmental variate. Perhaps the most useful components were the second and t h i r d which tended to select groups of species s p e c i f i c to an area or 118 depth. For t h i s reason, the c o r r e l a t i o n s with PC's II and III were p l o t t e d so that one c o u l d gain an immediate a p p r e c i a t i o n of the major e c o l o g i c a l groupings. I t i s worth emphasising that when s p e c i e s are s i g n i f i c a n t l y c o r r e l a t e d with a p a r t i c u l a r regime, they are not n e c e s s a r i l y the only ones i n t h i s regime, but are those e i t h e r f a v o u r i n g or a v o i d i n g such c o n d i t i o n s . N o n - c o r r e l a t e d species show no s i g n i f i c a n t p r e f e r e n c e s . What makes these c o r r e l a t i o n p l o t s i n t e r e s t i n g i s that one can i d e n t i f y s p e c i e s which are r e l a t e d to two regimes. For example, i n F i g u r e 3 those s p e c i e s along d i a g o n a l v e c t o r s i n the lower l e f t region of the p l o t were found i n s u r f a c e waters of both the NSG and MC i n March. As a s p e c i e s v e c t o r approaches e i t h e r the h o r i z o n t a l or the v e r t i c a l , a s p e c i e s i s i n c r e a s i n g l y c o r r e l a t e d with only one of the s p e c i f i e d regimes. D i s c r e p a n c i e s may occur i n some of the c a n o n i c a l models as the l o c a t i o n v a r i a b l e used i n the NSG vs MC s t a t i s t i c s was based on a g r a d i e n t , with lowest values f o r the southern NSG and hi g h e s t f o r the MC. I f the analyses were repeated, i t would be f a r l e s s c o n f u s i n g to use one code f o r each area (e.g., 1 = NSG, 2 = MC). In t h i s way one c o u l d be sure of the l o c a t i o n ' s meaning. As i t was i n the present study, a p o s i t i v e c o r r e l a t i o n c o u l d have been i n t e r p r e t e d as e i t h e r the MC or the northern NSG. A negative c o r r e l a t i o n may have i n d i c a t e d the southern NSG. 119 3.2 ORGANISMAL TRENDS WITH STRATIFICATION 3.2 .J_ March H o r i z o n t a l d i s t r i b u t i o n maps of temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n (determined as the change i n these parameters over 20 m) were c o n s t r u c t e d f o r each month. F i g u r e s 13a-c show the s t r a t i f i c a t i o n maps f o r March. I t should be mentioned that Stn 1a was omitted from the c o n t o u r i n g due to qu e s t i o n a b l e CTD data. Temperature s t r a t i f i c a t i o n was gr e a t e r on the mainland s i d e where i t i n c r e a s e d northward to a maximum of 0.6°C. S a l i n i t y s t r a t i f i c a t i o n was a l s o g r e a t e r on the east s i d e but i n c r e a s e d southward to a maximum of 4 ppt. S t r a t i f i c a t i o n due to d e n s i t y f o l l o w e d that of s a l i n i t y and reached a maximum of 3 sigma-t u n i t s . The s p e c i e s were p l a c e d i n t o organismal groups. In March the biomass c o n s i s t e d of diatoms (5.7%); p h o t o s y n t h e t i c d i n o f l a g e l l a t e s (1.4%); h e t e r o t r o p h i c d i n o f l a g e l l a t e s (21.5%); p h o t o s y n t h e t i c n a n o f l a g e l l a t e s (31.6%), which co n t a i n e d a l l n o n - d i n o f l a g e l l a t e f l a g e l l a t e s <20 nm; h e t e r o t r o p h i c n a n o f l a g e l l a t e s (1.8%); comprised of c h o a n o f l a g e l l a t e s and misc e l l a n e o u s z o o f l a g e l l a t e s ; p h o t o s y n t h e t i c f l a g e l l a t e s (1.7%), c o n s i s t i n g of E u t r e p t i e l l a , D i c t y o c h a speculum, and Heterosiqma  akashiwo; p h o t o s y n t h e t i c c i l i a t e s (3.3%), composed s o l e l y of Mesodinium rubrum; and h e t e r o t r o p h i c c i l i a t e s (33.0%), composed of t i n t i n n i d s and n o n - l o r i c a t e o l i g o t r i c h s , of which Strombidium was the most common. At each s t a t i o n , the biomass of the organismal groups was summed over the four depths and d i v i d e d by four to o b t a i n a value i n pg C « m l ~ 1 . Because these values were 120 somewhat cumbersome, a f u r t h e r d i v i s i o n by 1000 was done to present organismal biomass in ng O m l ~ 1 , which i s e q u i v a l e n t to Mg C « L ~ 1 . H o r i z o n t a l d i s t r i b u t i o n s of t h i s biomass are presented i n F i g u r e s 14a-i. Diatoms ( F i g . 14a) r a d i a t e d outward from Cape Lazo suggesting that f u r t h e r southwest diatoms were present i n g r e a t e r numbers. A net sample from Baynes Sound confirmed t h i s . Diatoms were the only organisms with t h i s d i s t r i b u t i o n a l p a t t e r n i n March. The p h o t o s y n t h e t i c d i n o f l a g e l l a t e s ( F i g . 14b), l a r g e r p h o t o s y n t h e t i c f l a g e l l a t e s ( F i g . 14g, e s p e c i a l l y e u g l e n o i d s ) , and Mesodinium rubrum ( F i g . 14h) had i n c r e a s e d i n D e s o l a t i o n Sound. H e t e r o t r o p h i c n a n o f l a g e l l a t e s ( F i g . 14i) were a l s o very l o c a l i s e d , p r e f e r r i n g the Hernando-Savary b a s i n . The dominants ( p h o t o s y n t h e t i c n a n o f l a g e l l a t e s ( F i g . 14e), h e t e r o t r o p h i c d i n o f l a g e l l a t e s ( F i g . 14e), and c i l i a t e s ( F i g . 14f)) a l l had s i m i l a r p a t t e r n s , with biomass maxima i n the t i d a l l y mixed area near S u t i l Channel and the waterway between Marina and Cortes I s l a n d s . The c i l i a t e s a l s o extended southwards down the s i d e s of the NSG whereas the n a n o f l a g e l l a t e s became numerous i n the southern m i d - S t r a i t . The h e t e r o t r o p h i c d i n o f l a g e l l a t e s ( F i g s . 14b-c), c o n s i s t i n g mostly of Gyrodinium s p i r a l e , appeared to d i s l i k e the southern water regime and m i r r o r e d the northern n a n o f l a g e l l a t e c o n c e n t r a t i o n as d i d c i l i a t e s . I t appeared that both may have been g r a z i n g on the small f l a g e l l a t e s . An attempt to r e l a t e these d i s t r i b u t i o n s to s t r a t i f i c a t i o n 121 can be made by l o o k i n g at biomass along each t r a n s e c t (presented as histograms) and the r e l e v a n t curves denoting the trends of temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n s . These p h y s i c a l data are from a l l s t a t i o n s whereas the b i o l o g i c a l data are from every other s t a t i o n . The s t r a t i f i c a t i o n v alues s p e c i f i c to the b i o l o g i c a l l y enumerated s t a t i o n s appear above t h e i r r e s p e c t i v e histograms. Along Transect 1 ( F i g . 15a), diatoms decreased from west to east whereas the h e t e r o t r o p h i c d i n o f l a g e l l a t e s i n c r e a s e d . P h o t o s y n t h e t i c n a n o f l a g e l l a t e s were most numerous m i d - S t r a i t while c i l i a t e s (assumed to be h e t e r o t r o p h i c ) were found i n g r e a t e r numbers along the s i d e s . A t r e n d emerges i n that i n m i d - S t r a i t the g r a z i n g p r e s s u r e due to d i n o f l a g e l l a t e s and c i l i a t e s would have been l e s s and consequently the n a n o f l a g e l l a t e s were more numerous. On the e a s t e r n s i d e , i t seems that the n a n o f l a g e l l a t e s c o u l d have been reduced s i g n i f i c a n t l y due to the presence of many g r a z e r s . The most obvious d i f f e r e n c e between m i d - S t r a i t and the east was that although temperature s t r a t i f i c a t i o n was roughly s i m i l a r , that due to s a l i n i t y and consequently d e n s i t y was twice as g r e a t . In T r a n s e c t 3 ( F i g . 15b), p h o t o s y n t h e t i c n a n o f l a g e l l a t e biomass remained the same whereas a l l the h e t e r o t r o p h s i n c r e a s e d from west to e a s t . A l l forms of s t r a t i f i c a t i o n a l s o i n c r e a s e d i n t h i s d i r e c t i o n . Again, g r a z e r s seemed to be, responding to s t r a t i f i c a t i o n , although i t was hard to see why they would be a f f e c t e d d i r e c t l y . Rather, i t may have been the n a n o f l a g e l l a t e s which were responding and p r o v i d i n g the necessary food. 122 A l l forms of s t r a t i f i c a t i o n i n c r e a s e d along Transect 4 ( F i g . 15c). Again, the h e t e r o t r o p h s responded p o s i t i v e l y from west to e a s t . N a n o f l a g e l l a t e s were most abundant m i d - S t r a i t even though g r a z e r s were very high. T h i s c o u l d i n d i c a t e a very p r o d u c t i v e p a r t of the S t r a i t . At Stn 4e h e t e r o t r o p h i c n a n o f l a g e l l a t e biomass was maximal. Trans e c t 5 ( F i g . 15d) had g r e a t e r biomass m i d - S t r a i t where s t r a t i f i c a t i o n was almost n o n - e x i s t e n t . On the east s i d e , where s t r a t i f i c a t i o n had i n c r e a s e d and temperature d i f f e r e n c e s were g r e a t e s t , the p h o t o s y n t h e t i c f l a g e l l a t e s (such as euglenoids and s i l i c o f l a g e l l a t e s ) and M. rubrum were at t h e i r maximum w i t h i n the NSG. T r a n s e c t 6 has been d i v i d e d i n t o two p a r t s , the f i r s t c o v e r i n g Malaspina I n l e t from D e s o l a t i o n Sound to the j u n c t i o n of the three i n l e t s ( F i g . 16a) and the second running from Okeover to L a n c e l o t I n l e t s ( F i g . 16b). Near the mouth of Malaspina, diatoms had become dominant, and at the j u n c t i o n , very dense. Despite the diatom bloom i t appears that the n a n o f l a g e l l a t e s had maintained a biomass s i m i l a r to t h a t w i t h i n the NSG. C i l i a t e s became l e s s a f a c t o r w i t h i n the main bloom. From D e s o l a t i o n Sound inward, temperature s t r a t i f i c a t i o n doubled while that due to s a l i n i t y and d e n s i t y decreased somewhat. Temperature s t r a t i f i c a t i o n remained r e l a t i v e l y h i g h i n Okeover then dropped o f f w i t h i n L a n c e l o t . S a l i n i t y and d e n s i t y s t r a t i f i c a t i o n at those s t a t i o n s enumerated f o r s p e c i e s decreased from Okeover to L a n c e l o t . Both i n l e t s had diatoms as dominants though L a n c e l o t ' s biomass was h i g h e r . 123 F i g u r e s 13a-c. S t r a t i f i c a t i o n contours f o r the northern S t r a i t of Georgia, March 18-19, 1986. a. Temperature d i f f e r e n c e (AT = °C) between the s u r f a c e and 20 m. b. S a l i n i t y d i f f e r e n c e (AS = ppt) between the s u r f a c e and 20 m. c. Density d i f f e r e n c e (AD = at) between the sur f a c e and 20 m. F i g u r e s 14a-i. Organismal biomass (ng C«ml~ 1) contours f o r the northern S t r a i t of Georgia, March 18-19, 1986. a. Diatoms b. P r o t o p e r i d i n i u m spp. c. Other h e t e r o t r o p h i c d i n o f l a g e l l a t e s d. P h o t o s y n t h e t i c d i n o f l a g e l l a t e s e. P h o t o s y n t h e t i c n a n o f l a g e l l a t e s f. H e t e r o t r o p h i c c i l i a t e s g. P h o t o s y n t h e t i c f l a g e l l a t e s h. Mesodinium rubrum i . H e t e r o t r o p h i c n a n o f l a g e l l a t e s 124 F i g u r e 14. March Biomass (ngC-ml" 1) a.Diatoms b.Protoperid inium c.Hetero-Dlnos 126 127 F i g u r e 14. March Biomass (ng C-ml - 1 ) g.Photo-Flags h.Mesodinium 1.Hetero-Nanos 128 F i g u r e s 15a-d. Temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n along t r a n s e c t s i n the northern S t r a i t of Georgia from west ( l e f t = Vancouver I s l a n d s i d e ) to east ( r i g h t = mainland s i d e ) , March 18-19,1986. Each s t r a t i f i c a t i o n p l o t shows value s f o r the s t a t i o n s . When data f o r a p a r t i c u l a r s t a t i o n are m i s s i n g , the curves may be i n t e r r u p t e d . Below the s t r a t i f i c a t i o n p l o t s l i e histograms f o r the 3 s t a t i o n s b i o l o g i c a l l y enumerated. Organismal codes are as f o l l o w s : d i a t o = diatoms pdino = p h o t o s y n t h e t i c d i n o f l a g e l l a t e s hdino = h e t e r o t r o p h i c d i n o f l a g e l l a t e s pnano = p h o t o s y n t h e t i c n a n o f l a g e l l a t e s hnano = h e t e r o t r o p h i c n a n o f l a g e l l a t e s p f l a g = p h o t o s y n t h e t i c f l a g e l l a t e s mesod = Mesodinium rubrum c i l i a = h e t e r o t r o p h i c c i l i a t e s a. Transect 1 b. Transect 3 c. Transect 4 d. Transect 5 F i g u r e s 16a-b. Temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n along t r a n s e c t s i n Malaspina Complex, March 18 - 1 9 , 1986. Histogram codes are as above. a. Transect 6a: Malaspina I n l e t from D e s o l a t i o n Sound ( l e f t ) to the i n l e t s j u n c t i o n ( r i g h t ) . b. Transect 6b: Okeover I n l e t ( l e f t ) and L a n c e l o t I n l e t ( r i g h t ) with the j u n c t i o n i n the middle. 129 F i g u r e 15. Northern S t r a i t of Georgia. March 18-19. a. Transect 1 r-I a? -p — 100 ar a S E s * o U cj) ta c 10 1 O O O O O O O I - D O • H - P C C C T I B O C f a . j r a a u a . B j r J3_ O O O O O O O T J O • M * » C C C - r * B J O C O O * - t « - l 0 r - l f - t a O • « L O B C H » . a c u a j r a a o a B x : 0 ^ O O O O O O C X T J O • U - P C C C - ^ O O C n a j r a a u a s c b. Transect 3 t 0 +» r-« 0 Q 1 0.8 0.6 0.4 0.2 0 • 4 3 • 5 A • 2.5 < 3 CO I 2 a 0 *J 2 1.5 r 0 1 f o a 4 ^ — 1 r-t 0 CI 0.5 ~ 100 0 ca c 10 1 >• i o o o o o a n x i o • M * * C C C " r t 0 O C 0 O w t « 4 0 r - t i - f B > 0 x i a j r a a u a B j r o o o o o o a x i o • M - W C C C » « 0 O C 0 O « - l « - l 0 i - f r 4 0 0 0 0 0 0 0 0 9 X 1 0 • P - W C C C - r l O O C »-« C- TJ TJ C O C n a c a a u a B c 130 F i g u r e 15. Northern S t r a i t of Georgia, March 18-19. c . T r a n s e c t 4 i 0 *1 ~ too 0*7 0 E £ cn 1 0 to c ft S aw 0 0 0 0 0 0 0 - 0 0 • V - P C C C « 4 0 O C 0 o « « « 4 0 i - f f - i a 0 o a c a a u a e x : 0 0 0 0 0 0 0 1 - 0 0 4 * 4 J C C C - n 0 o e 0 O « 4 « - t 0 r - f f f B 0 - a a c a a u a s c p£1 0 0 0 0 0 0 0 1 - 0 0 - t » - K C C C « - ! 0 O C 0 O < - > - r 4 0 r - t r - I B i O •< L TJ TJ C »< »• 0 C - o a c a . a u a . B f d . T r a n s e c t S i 0 f-i o a 0 0 0 0 0 0 0 1 0 0 • P - W C C C - r f O O C 0 O ~ « « 4 0 i - l f - l 0 0 » « t - " O - O C * « » - 0 C - o a c a a u a B z : 0 0 0 0 0 0 0 0 1 - 0 0 + » * i C C C w « 0 O C a o - n ^ e i - i r - i o o e - o a x : a a u a B . c 0 0 0 0 0 0 0 ) 0 0 • f - U C C C - r t O O C 0 O - r 4 - r 4 O r - l r - i a 0 c o o c * * * - o c - o a c a a u a e c 131 i 0 J J i - l CD Q CO ' -g ? o U to c F i g u r e 16. Malaspina Complex, March 18-19. a. Transect 6a - Malaspina 0 0 0 0 0 0 0 - 0 0 0 O « 4 « 4 0 r - l f - I B 0 « - > C T J T 3 C « - l » - a ) C o o o o o o o o o 0 O « - l « - t 0 f - t f - t a ) 0 " • • C O T » C « - I ^ 0 C u a j c a a u a B j c b. Transect 6b - Okeover S Lancelot i 0 +» i-i o a 1"L § ? o U m c 1 0.8 0.6 0.4 0.2 0 _ too 10 1 o cn i 0 0 a 4 3 2 1 0 I 0 0 0 0 0 0 0 0 0 + » - P C C C - r t 0 O C 0 O « 4 « 4 0 r - l i - i n 0 T 3 a . J C a . a . u a B c L 0 0 0 0 0 0 0 - 0 0 • V - M C C C - r i O O C 0 O v 4 < r l fl H ri 0 0 L TJ TJ C •< »• 0 c i 3 a . f a a . u a . B j c 0 0 0 0 0 0 0 1 - 0 0 • v j y c c c ' i o o c o o « - i « 4 0 p 4 i - i a 0 < n e . ' o - o c * * < » - 0 c o a c a a u a B f 132 3.2.2 A p r i l S t r a t i f i c a t i o n maps f o r A p r i l are presented i n F i g s . 17a-c. Temperature s t r a t i f i c a t i o n was g r e a t e r on the east s i d e than the west s i d e and reached a maximum of 1.2°C i n the Hernando-Savary b a s i n . S a l i n i t y s t r a t i f i c a t i o n was a l s o g r e a t e r on the east s i d e , reaching a maximum of 2 ppt i n the south, perhaps r e f l e c t i n g the i n f l u e n c e of the F r a s e r plume. Densi t y s t r a t i f i c a t i o n was again determined by s a l i n i t y with a maximum at d i f f e r e n c e of 1.5 o f f Powell R i v e r . A p r i l ' s organismal biomass was composed of diatoms (8.3%), p h o t o s y n t h e t i c d i n o f l a g e l l a t e s (1.5%), h e t e r o t r o p h i c d i n o f l a g e l l a t e s (13.1%), p h o t o s y n t h e t i c n a n o f l a g e l l a t e s (48.0%), h e t e r o t r o p h i c n a n o f l a g e l l a t e s (0.5%), p h o t o s y n t h e t i c f l a g e l l a t e s (0.8%), p h o t o s y n t h e t i c c i l i a t e s (3.5%), and h e t e r o t r o p h i c c i l i a t e s (24.3%). Many of the organisms appeared to be most abundant on the western s i d e . The dominant n a n o f l a g e l l a t e s ( F i g . I8e) were co n c e n t r a t e d roughly h a l f way down from D i s c o v e r y Passage to Cape Lazo, as was Mesodinium rubrum ( F i g . I8h). Mesodinium i s w e l l adapted to tu r b u l e n c e , p a r t i c u l a r l y i n areas of u p w e l l i n g , because of i t s high swimming r a t e of 1 to 2 mm«s~ 1 and sometimes >5 mm»s" 1 (Lindholm, 1985). Again, n a n o f l a g e l l a t e s were co n c e n t r a t e d i n the most t i d a l l y mixed region of the S t r a i t . Diatoms ( F i g . 18a), a l l d i n o f l a g e l l a t e s ( F i g s . I8b-d), and h e t e r o t r o p h i c n a n o f l a g e l l a t e s ( F i g . I 8 i ) were conc e n t r a t e d f u r t h e r south along t h i s s i d e , t w o - t h i r d s of the way to Cape Lazo. There must have been some g r a z i n g i n t e r a c t i o n s o c c u r r i n g 133 as the h e t e r o t r o p h i c d i n o f l a g e l l a t e s i n c l u d e d g r a z e r s on diatoms, and p h o t o s y n t h e t i c d i n o f l a g e l l a t e s and n a n o f l a g e l l a t e s . P r o t o p e r i d i n i u m and Gyrodinium e x h i b i t e d s i m i l a r p a t t e r n s and tended to concentrate i n areas of peak diatom and p h o t o s y n t h e t i c d i n o f l a g e l l a t e biomass, j u s t south of the p h o t o s y n t h e t i c n a n o f l a g e l l a t e biomass. As mentioned e a r l i e r , c e r t a i n s p e c i e s of P r o t o p e r i d i n i u m graze diatoms (e.g., P. conicum and P. depressum (Gaines & T a y l o r , 1984) as do some s p e c i e s of Gyrodinium (Smetacek, 1981). There was a d i f f e r e n t t r e n d e x h i b i t e d by the h e t e r o t r o p h i c c i l i a t e s ( F i g . 18f) where biomass i n c r e a s e d toward the south and was c o n c e n t r a t e d on the east s i d e near Powell R i v e r . These organisms had perhaps grazed the n a n o f l a g e l l a t e s down to lower l e v e l s i n t h i s area. Along Transect 1 ( F i g . 19a), the c i l i a t e s i n c r e a s e d somewhat from west to east while the h e t e r o t r o p h i c d i n o f l a g e l l a t e s decreased. O v e r a l l , however, microzooplankton g r a z i n g p r e s s u r e c o u l d have been c o n s t a n t . The n a n o f l a g e l l a t e biomass was e l e v a t e d on the west s i d e and perhaps responded to something other than g r a z i n g p r e s s u r e . H e t e r o t r o p h i c d i n o f l a g e l l a t e s were abundant on the west s i d e of Transect 3 ( F i g . 19b) but v i r t u a l l y disappeared f u r t h e r e a s t . In f a c t , a l l the major groups tended to become reduced at the e a s t e r n s t a t i o n , which e x h i b i t e d the g r e a t e s t s t r a t i f i c a t i o n of the three enumerated s t a t i o n s . The n a n o f l a g e l l a t e s were the major p h o t o s y n t h e t i c organisms on the whole t r a n s e c t but diatoms became more abundant at each end. 134 Transect 4 ( F i g . 19c) showed the l e a s t s t r a t i f i c a t i o n m i d - S t r a i t and the most on the e a s t e r n s i d e . There was a concurrent i n c r e a s e i n n a n o f l a g e l l a t e s with s t r a t i f i c a t i o n and decrease i n diatoms. However, while s t r a t i f i c a t i o n was s l i g h t on the western s i d e , most groups had higher biomass i n t h i s r e g i o n . The s a l i n i t y - d e n s i t y s t r a t i f i c a t i o n d i d not change markedly a c r o s s T r a n s e c t 5 ( F i g . I9d) with respect to the b i o l o g i c a l s t a t i o n s . However, Stn 5e d i d show a higher degree of temperature s t r a t i f i c a t i o n . T h i s d i f f e r e n c e may have had a s t i m u l a t o r y e f f e c t on the p h o t o s y n t h e t i c n a n o f l a g e l l a t e s because they were most abundant t h e r e . Transect 6a ( F i g . 20a) saw a great i n c r e a s e i n diatoms towards the j u n c t i o n of the i n l e t s . Smaller i n c r e a s e s o c c u r r e d in the d i n o f l a g e l l a t e s while the n a n o f l a g e l l a t e s decreased. Over t h i s d i s t a n c e there was a 9 - f o l d i n c r e a s e i n temperature s t r a t i f i c a t i o n and a 5 - f o l d i n c r e a s e i n s a l i n i t y s t r a t i f i c a t i o n . W ithin the complex (Transect 6b, F i g . 20b), temperature s t r a t i f i c a t i o n remained f a i r l y constant but s a l i n i t y s t r a t i f i c a t i o n was higher at Okeover I n l e t ' s head. Surface n i t r a t e v a l u e s were low i n Okeover I n l e t (<1 M M ) . 135 F i g u r e s 17a-c. S t r a t i f i c a t i o n contours f o r the northern S t r a i t of Georgia, A p r i l 22-23, 1986. a. Temperature d i f f e r e n c e (AT = °C) between the s u r f a c e and 20 m. b. S a l i n i t y d i f f e r e n c e (AS = ppt) between the s u r f a c e and 20 m. c. Den s i t y d i f f e r e n c e (AD = at) between the s u r f a c e and 20 m. F i g u r e s I 8 a - i . Organismal biomass (ng C«ml" 1) contours f o r the northern S t r a i t of Georgia, A p r i l 22-23, 1986. a. Diatoms b. P r o t o p e r i d i n i u m spp. c. Other h e t e r o t r o p h i c d i n o f l a g e l l a t e s d. P h o t o s y n t h e t i c d i n o f l a g e l l a t e s e. P h o t o s y n t h e t i c n a n o f l a g e l l a t e s f . H e t e r o t r o p h i c c i l i a t e s g. P h o t o s y n t h e t i c f l a g e l l a t e s h. Mesodinium rubrum i . H e t e r o t r o p h i c n a n o f l a g e l l a t e s 136 137 138 139 140 F i g u r e s I9a~d. Temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n along t r a n s e c t s i n the northern S t r a i t of Georgia from west ( l e f t = Vancouver I s l a n d s i d e ) to east ( r i g h t = mainland s i d e ) , A p r i l 22-23, 1986. Each s t r a t i f i c a t i o n p l o t shows values f o r the s t a t i o n s . When data f o r a p a r t i c u l a r s t a t i o n are m i s s i n g , the curves may be i n t e r r u p t e d . Below the s t r a t i f i c a t i o n p l o t s l i e histograms f o r the 3 s t a t i o n s b i o l o g i c a l l y enumerated. Organismal codes are as f o l l o w s : d i a t o = diatoms pdino = p h o t o s y n t h e t i c d i n o f l a g e l l a t e s hdino = h e t e r o t r o p h i c d i n o f l a g e l l a t e s pnano = p h o t o s y n t h e t i c n a n o f l a g e l l a t e s hnano = h e t e r o t r o p h i c n a n o f l a g e l l a t e s p f l a g = p h o t o s y n t h e t i c f l a g e l l a t e s mesod = Mesodinium rubrum c i l i a = h e t e r o t r o p h i c c i l i a t e s a. Transect 1 b. Transect 3 c. Transect 4 d. Transect 5 F i g u r e s 20a~b. Temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n a long t r a n s e c t s i n Malaspina Complex, A p r i l 22-23, 1986. Histogram codes are as above. a. Transect 6a: Malaspina I n l e t from D e s o l a t i o n Sound ( l e f t ) to the i n l e t s j u n c t i o n ( r i g h t ) . b. Transect 6b: Okeover I n l e t ( l e f t ) and L a n c e l o t I n l e t ( r i g h t ) with the j u n c t i o n i n the middle. 141 F i g u r e 19. Northern S t r a i t of Georgia. A p r i l 22-23. a. Transect 1 0 0 0 0 0 0 9 0 0 o o o o o o a o o o o o o o o a o o + » - u c e c - « - t o o c - u - v c c c ^ - t a o c - P - P C C : C « - « O O C 0 o « 4 « 4 O r i i - f n a a o » 4 « 4 a r - i i - f ( o a g o H ^ a n H g n rfC.TJTJC'fl-lllC « 4 C O O C « 4 « - C 0 C rtLTJDC^t-BC - o a c a a u a B i r o a c a a u a s c o a c a a u a s c b. Transect 3 o o o o o o a o o o o o o o o a o o o o o o o o a o o • U 4 J C C C * 4 0 O C • M - U C C C ' t O O C J U J P C C C " - » O O C a o » < « o > - t f - t a a o o » « » - t f l < - » i - i B o o o « - » « - » o > - » r - i n o H t. T J TJ C ID C H L D T J C ^ v a C « - I L T 3 T 3 C « - » » - a J C - o a c a a u a s c o a c a a u a B c o a . j c a a . u a . B j c 142 F i g u r e 19. Northern S t r a i t of Georgia. A p r i l 22-23. c. Transect 4 • r-I 0 4* r-i O Q S E 5 u O O O O O 0 O T I O • u - u c c c - n o o c 0 O « 4 « 4 0 l - l f - t a 0 a a c a a u a B c 0 0 0 0 0 0 0 X 7 0 4 J > 4 J C C C - r t 0 O C no«-««-i(0'-ir-fB) a n a c a a u a B c o o o o o o a - a o • P * » C C C - r t 0 O C 0 o < - « « 4 0 i - i i - f n 0 - o a . . c a . a . u a . B x : d. Transect 5 i 0 • u r-t 0 a o O CO c 100 r 10 P a O O O O O O O T J O • P - U C C C - r l O O C 0 O « 4 * 4 0 l - l i - t 0 0 L TI O C 0 C u a c a a u a B c i o o o o o o a - a o • U - M C C C < r 4 0 0 C 0 O « - f « 4 0 l - l . - I B O • < 1 . T J B C H V « C - o o . j r a a u a . B x : o o o o o o a x i o • U - U C C C ' - f O O C a o « 4 « 4 O . - * i - t 0 e x i a c a a u a B j c 143 F i g u r e 20. Malaspina Complex. A p r i l 22-23. a. Transect 6a - Malaspina 1.4 1.2 1 0.8 0.6 0.4 0.2 100 2 r o 1.3 • at I 0 *J r-t 1 • 0 Q O.sL 1.5 -0 0 0 0 0 0 9 0 0 * » - M C C C * « 0 o C 0 O « 4 « - t 0 l - 4 r - f 0 0 « - I C O ' O C « - t « - 0 C • o a j c a a u a B J C 0 0 0 0 0 0 9 0 0 • V - M C C C < r 4 0 O C 0 O « - t « - t 0 l - 4 r 4 0 0 C O O C «•» » - 0 c o a . j c a o . u o . B x : b. Transect 6b - Okeover S Lancelot 1.4 i . 2 l 1 0.8 0.6 0.4 0.2 1.5 CO I 5 i 0 a 0.3 4 - 5 < Ji 1 o i 0 *1 0.5 a lOOi 10 r I I 0 O O O O O 0 9 - O O 0 O * - t « 4 0 r - f f - t 0 0 •< t. TI TJ C H » . 0 C ' o a x r a a u a B j c O O O O O 0 9 X I O 4 J - P C C C - H 0 O C 0 O - > - » « - l 0 l - » i - f 0 0 • r < C . O O C « - » « » - 0 C T J a j c a a u a B r 0 0 0 0 0 0 9 - 0 0 • M - M C C C - r < 0 O C 0 O « - t « - l 0 f - t i - I B 0 • 4 C O O C « - f « - O C o a j c a a u a B j c 144 3_.2_.3_ June The s t r a t i f i c a t i o n maps f o r June are presented i n F i g u r e s 21a-c. The east s i d e was most temperature s t r a t i f i e d r eaching a d i f f e r e n c e of 5°C. The area o f f Cape Lazo a l s o reached a AT of 5°C. S a l i n i t y s t r a t i f i c a t i o n was g r e a t e s t along the east s i d e e s p e c i a l l y i n the Hernando-Savary b a s i n (AS = 4 p p t ) . O v e r a l l , d e n s i t y s t r a t i f i c a t i o n was hi g h e s t along the east s i d e r e a c h i n g a Afft of 4.5. The waters o f f Cape Lazo were a l s o s t r a t i f i e d . I t was q u i t e evident that the Disc o v e r y Passage t i d a l j e t had upset s t r a t i f i c a t i o n i n the northwest (though not completely as Aat 2). I t s e f f e c t swept out i n t o m i d - S t r a i t h a l f way down the NSG and c o n t i n u e d southward u n t i l at l e a s t Transect 1. Organismal biomass val u e s were as f o l l o w s : 0.9% diatoms, 10.3% p h o t o s y n t h e t i c d i n o f l a g e l l a t e s , 13.0% h e t e r o t r o p h i c d i n o f l a g e l l a t e s , 16.7% p h o t o s y n t h e t i c n a n o f l a g e l l a t e s , 0.2% h e t e r o t r o p h i c n a n o f l a g e l l a t e s , 13.0% ph o t o s y n t h e t i c f l a g e l l a t e s , 2.2% p h o t o s y n t h e t i c c i l i a t e s , and 43.8% h e t e r o t r o p h i c c i l i a t e s . N early a l l the organismal groups were concentrated i n the northwest where waters were l e a s t s t r a t i f i e d . Obviously t h i s must have been a r e g u l a r source of e n t r a i n e d n u t r i e n t s i n a s t r a t i f i e d regime where n u t r i e n t - p o o r s u r f a c e waters were the norm. Diatoms ( F i g . 22a) c o n s t i t u t e d very l i t t l e of the biomass and were the only group which e x h i b i t e d a d i f f e r e n t d i s t r i b u t i o n . They were most abundant o f f Cape Lazo i n one of the more s t r a t i f i e d a r e a s . At t h i s time of year when l i g h t l i m i t a t i o n was minimal, one might expect to see the diatoms most abundant i n areas of turbulence and t h e i r a s s o c i a t e d n u t r i e n t 145 regimes; however, such was not the case. Instead, i t was the p h o t o s y n t h e t i c n a n o f l a g e l l a t e s and p h o t o s y n t h e t i c d i n o f l a g e l l a t e s which responded to t h i s t i d a l t u r b u l e n c e . The g r a z e r s responded to the i n c r e a s e d biomass. Tran s e c t 1 ( F i g . 23a) e x h i b i t e d s t r a t i f i e d waters on both s i d e s with moderately s t r a t i f i e d m i d - S t r a i t waters. The east was s l i g h t l y more temperature s t r a t i f i e d than the west. C i l i a t e s and h e t e r o t r o p h i c d i n o f l a g e l l a t e s were more abundant on the east s i d e and t h e r e f o r e must have exe r t e d a g r e a t e r g r a z i n g pressure t h e r e . In Transect 3 ( F i g . 23b), a high degree of s t r a t i f i c a t i o n was present on the east s i d e but not on the west. Temperature's c o n t r i b u t i o n remained much the same as i n the p r e v i o u s t r a n s e c t while s a l i n i t y s t r a t i f i c a t i o n i n c r e a s e d . The n a n o f l a g e l l a t e s remained constant a c r o s s the S t r a i t but must have been reproducing at a higher r a t e on the west s i d e as g r a z i n g pressure from c i l i a t e s was h i g h e r . Nearly a l l the organisms were more numerous on the west s i d e . Along Transect 4 ( F i g . 23c) maximal s t r a t i f i c a t i o n o c c u r r e d i n the Hernando-Savary basin with a decrease at Stn 4e. Temperature s t r a t i f i c a t i o n decreased on the east s i d e compared to more s o u t h e r l y t r a n s e c t s . S t i l l , the p a t t e r n was lower s t r a t i f i c a t i o n i n the west, higher i n the e a s t . Most organisms were more abundant on the west sid e except p h o t o s y n t h e t i c f l a g e l l a t e s , c o n s i s t i n g c h i e f l y of Heterosigma akashiwo, which showed even biomass a c r o s s the S t r a i t . Although s t r a t i f i c a t i o n remained higher on the east s i d e of 146 Transect 5 ( F i g . 23d), s t r a t i f i c a t i o n i n g e n e r a l decreased. M i d - S t r a i t , the s a l i n i t y d i f f e r e n c e was at a minimum and so were the c i l i a t e s . S t a t i o n 5a had the same d e n s i t y d i f f e r e n c e as i n m i d - S t r a i t but i t s s a l i n i t y d i f f e r e n c e had more than doubled. Here c i l i a t e biomass was very h i g h . C i l i a t e s were e i t h e r responding markedly to s a l i n i t y s t r a t i f i c a t i o n or Stn 5a was an u n u s u a l l y p r o d u c t i v e area f o r food g e n e r a t i o n . Very s u r p r i s i n g l y , Malaspina I n l e t (Transect 6a, F i g . 24a) became f a r l e s s s t r a t i f i e d than D e s o l a t i o n Sound. T h i s may have been due to the powerful t i d a l mixing f o r c e . S t r a t i f i c a t i o n decreased but the p h o t o s y n t h e t i c forms i n c r e a s e d . One c o u l d a t t r i b u t e t h i s to i n j e c t i o n of n u t r i e n t s on an incoming t i d e ; however, the n i t r a t e l e v e l s were very reduced. Along Transect 6b ( F i g . 24b) Okeover and L a n c e l o t were s l i g h t l y more s t r a t i f i e d away from the j u n c t i o n . At Okeover I n l e t ' s head, temperature s t r a t i f i c a t i o n was g r e a t e s t (of the three b i o l o g i c a l s t a t i o n s ) and there was a huge i n c r e a s e i n Mesodinium biomass. L a n c e l o t I n l e t , on the other hand, had exceedingly low s t r a t i f i c a t i o n values with reduced biomass f o r a l l organisms except the p h o t o s y n t h e t i c n a n o f l a g e l l a t e s and Mesodinium. I n t e r e s t i n g l y , M. rubrum was abundant i n both i n l e t s but appeared to a v o i d the t i d a l l y - m i x e d j u n c t i o n . 147 F i g u r e s 2 l a - c . S t r a t i f i c a t i o n contours f o r the northern S t r a i t of Georgia, June 25-26, 1986. a. Temperature d i f f e r e n c e (AT = °C) between the s u r f a c e and 20 m. b. S a l i n i t y d i f f e r e n c e (AS = ppt) between the s u r f a c e and 20 m. c. D e n s i t y d i f f e r e n c e (AD = at) between the s u r f a c e and 20 m. F i g u r e s 2 2 a - i . Organismal biomass (ng C«ml~ 1) contours f o r the northern S t r a i t of Georgia, June 25-26, 1986. a. Diatoms b. P r o t o p e r i d i n i u m spp. c. Other h e t e r o t r o p h i c d i n o f l a g e l l a t e s d. P h o t o s y n t h e t i c d i n o f l a g e l l a t e s e. P h o t o s y n t h e t i c n a n o f l a g e l l a t e s f . H e t e r o t r o p h i c c i l i a t e s g. Ph o t o s y n t h e t i c f l a g e l l a t e s h. Mesodinium rubrum i . H e t e r o t r o p h i c n a n o f l a g e l l a t e s F i g u r e 21. J u n e S t r a t i f i c a t i o n a.Del ta -T b.Delta-S c.Delta-D 149 152 F i g u r e s 23a-d. Temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n along t r a n s e c t s i n the northern S t r a i t of Georgia from west ( l e f t = Vancouver I s l a n d s i d e ) to east ( r i g h t = mainland s i d e ) , June 25-26, 1986. Each s t r a t i f i c a t i o n p l o t shows values f o r the s t a t i o n s . When data f o r a p a r t i c u l a r s t a t i o n are m i s s i n g , the curves may be i n t e r r u p t e d . Below the s t r a t i f i c a t i o n p l o t s l i e histograms f o r the 3 s t a t i o n s b i o l o g i c a l l y enumerated. Organismal codes are as f o l l o w s : d i a t o = diatoms pdino = p h o t o s y n t h e t i c d i n o f l a g e l l a t e s hdino = h e t e r o t r o p h i c d i n o f l a g e l l a t e s pnano = p h o t o s y n t h e t i c n a n o f l a g e l l a t e s hnano = h e t e r o t r o p h i c n a n o f l a g e l l a t e s p f l a g = p h o t o s y n t h e t i c f l a g e l l a t e s mesod = Mesodinium rubrum c i l i a = h e t e r o t r o p h i c c i l i a t e s a. Transect 1 b. Transect 3 c. Transect 4 d. Transect 5 F i g u r e s 24a-b. Temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n along t r a n s e c t s i n Malaspina Complex, June 25-26, 1986. Histogram codes are as above. a. Transect 6a: Malaspina I n l e t from D e s o l a t i o n Sound ( l e f t ) to the i n l e t s j u n c t i o n ( r i g h t ) . b. Transect 6b: Okeover I n l e t ( l e f t ) and L a n c e l o t I n l e t ( r i g h t ) with the j u n c t i o n i n the middle. 153 F i g u r e 23. Northern S t r a i t of Georgia. June 25-26. s. Transect 1 100 r 10 1 re ULFA 0 0 0 0 0 0 9 0 0 • V 4 J > c c c < n a o c a o - f - f - n o r - i r - i a a L TJ n c * • a c - o a . f a a . u a . B j c 0 0 0 0 0 0 9 0 0 0 O « 4 « - t 0 r - t r - t 0 0 - o a j c a a u a B f o o o o o o a o o 4 J 4 J C C C * 4 0 O C 0 o » « « - i 0 i - ( i - f a 0 • • i c o o c » * * • o c u a j c a a u a B j c b. Transect 3 7 • Q 1 7 6 • 6 • o • < 5 5 CO i 0 4 . . . -O y> 4 a t 0 3 3 JJJ 0 o 2 2 0 • 1 1 6 S 4 3 2 1 100 10 1 N O O O O O 0 9 O O • P - P C C C 1 0 O C 0 O - l - < - l 0 > - l r - t a 0 » « C O O C » « * - 0 C - n o . j c a a u a . B x : O O O O O 0 9 - O O • M - P C C C - H 0 O C 0 O « 4 « - t 0 l - l i - I B 0 • * * C . - O - O C w * » - 0 C - o a j c a a u a B c 0 0 0 0 0 0 0 ) 0 0 • M J J J C C C - T 4 0 O C 0 O * - > « - l 0 r - l r - > 0 0 » - « c . - o - o c « - i » - 0 e o a j c a a u a B x : 154 F i g u r e 19. Northern S t r a i t of Georgia. June 25-26, c. Transect 4 100 r 10 r Jli o o o o o o a - a o • M - W C C C - H O O C oo«««40f-i l-iae »l L T J T J C H v a c T J a. x: a. a. u a B c o o o o o o a x i o • M * » C C C « - I O O C O O < r * « 4 0 i - t r - i n O « - * C X I X I C « - l * - 0 C T 3 a . i z a o . u a B x : o o o o o o a x i o • u - P c c c - r i e o c o o - t - i < - f O i - i > - « n o x t a j z a a u a s x : d. Transect 5 1001 10 1 «• o o o o o o a x i o • u - u c c C ' t a o c a o « 4 w < o i - i i - i o a H C. O T) C H »• O C x i a x r a a u a B x : o o o o o o a x i o • M J J C C C - n O O C O O ^ - f ^ t O r - f r - f a O x i a x : a a u a B x : o o o o o o a x i o • v - v c c c ^ e o c ao«4«-iOf-ii-ine «< t T J T J c •< * • a c x i a x r a a u a s x : 155 F i g u r e 24. Malaspina Complex, June 25-26 too 10 a. Transact 6a - Malaspina \1 2^ 0 0 0 0 0 0 9 0 0 4 J * > C C C - < - I O O C 0 0 « 4 « 4 0 r - t r - t n O •H C. O O C ••» * • O C o a. c a a u a B r 0 0 0 0 0 0 9 0 0 • M 4 J C C C < H O O C ( 0 O - r 4 « - I B r - l l - i e 0 a » « c . o o c « * » - « c o a j c a a u a B x : b. Transect 6b - Okeover S Lancelot 100 r 10 • 1 •* 0 0 0 0 0 0 9 - 0 0 J P J J J C C C - ^ O O C o o < r i t - i o > - i i - i a o « 4 C - O O C - ^ « - O C o a c a a u a e c 0 0 0 0 0 0 9 - 0 0 • P J V C C C ^ O O C e o ^ - n o i - i i - f a a » « C . - D O C « - « » - f f l C - o a j c a a . u a . 8 c o o o o o o a o o a o < r i - r 4 0 i - i < - i a o « - t £ . O ^ O C - » « » - « C - o a c a a u a B j c 156 3.2.4 August H o r i z o n t a l d i s t r i b u t i o n maps of s t r a t i f i c a t i o n are presented i n F i g s . 25a-c. Temperature s t r a t i f i c a t i o n was maximal (8°C) i n the southern c e n t r a l area of the NSG. S a l i n i t y s t r a t i f i c a t i o n was g r e a t e s t i n the n o r t h e a s t near Twin I s l a n d s (4 ppt) and a l s o i n c r e a s e d o f f Powell R i v e r . D e n s i t y s t r a t i f i c a t i o n maxima responded to the s a l i n i t y d i f f e r e n c e o f f Powell R i v e r and to the temperature d i f f e r e n c e i n the c e n t r a l S t r a i t . Again there was a zone of upset s t r a t i f i c a t i o n extending from the northwest down the west s i d e , c u r v i n g out i n t o m i d - S t r a i t where i t continued southward. Organismal biomass was overwhelmingly dominated by diatoms (78.0%), f o l l o w e d by p h o t o s y n t h e t i c n a n o f l a g e l l a t e s (8.3%), h e t e r o t r o p h i c c i l i a t e s (5.3%), h e t e r o t r o p h i c d i n o f l a g e l l a t e s (5.0%), p h o t o s y n t h e t i c d i n o f l a g e l l a t e s (2.6%), p h o t o s y n t h e t i c f l a g e l l a t e s (0.5%), p h o t o s y n t h e t i c c i l i a t e s (0.3%), and h e t e r o t r o p h i c n a n o f l a g e l l a t e s (0.1%). Diatoms ( F i g . 26a) were most abundant near the entrance to S u t i l Channel and o f f Cape Lazo. P r o t o p e r i d i n i u m a l s o e x h i b i t e d t h i s d i s t r i b u t i o n . T h i s group now seemed to be composed of diatom g r a z i n g s p e c i e s , judging by the c l o s e n e s s of the p a t t e r n . The diatom p a t t e r n was i n t e r e s t i n g i n that these organisms had become the dominants i n t i d a l l y mixed areas of the north and west. There was a l s o a s t i m u l a t i o n of biomass between Savary I s l a n d and the mainland. In a l l these areas there was probably an entrainment of n u t r i e n t s from below the p y c n o c l i n e by t i d a l streaming. The diatoms were conc e n t r a t e d between 10-15 m depth 157 and were presumably i n the region of the p y c n o c l i n e where n u t r i e n t f l u x i s higher and l i g h t i s s u f f i c i e n t f o r growth. The p h o t o s y n t h e t i c d i n o f l a g e l l a t e s ( F i g . 26d), p h o t o s y n t h e t i c n a n o f l a g e l l a t e s ( F i g . 26e), and M. rubrum, ( F i g . 26h) were a l l f a v o u r i n g the east and south s i d e s . Of these t h r e e , the n a n o f l a g e l l a t e s c o n t r i b u t e d the most to the biomass. F o l l o w i n g t h e i r d i s t r i b u t i o n and presumably g r a z i n g on the n a n o f l a g e l l a t e s were c i l i a t e s ( F i g . 2 6 f ) . Up u n t i l now, the n a n o f l a g e l l a t e s had p r e f e r r e d the t i d a l l y - m i x e d areas of the S t r a i t but seem to have been d i s p l a c e d by the i n c r e d i b l e growth of diatoms. Perhaps there was c o m p e t i t i v e e x c l u s i o n o c c u r r i n g based on n u t r i e n t uptake. Diatoms would be f i r s t i n l i n e f o r any t r a n s p o r t of n u t r i e n t s from below the n u t r i c l i n e . In Transect 1 ( F i g . 27a), the f i r s t set of histograms belongs to Stn 1b as 1a was m i s s i n g i t s CTD data and consequently was not b i o l o g i c a l l y enumerated. From west to east the dominant cause of s t r a t i f i c a t i o n changed from temperature to s a l i n i t y . Where temperature s t r a t i f i c a t i o n was h i g h e s t , the diatom biomass was very high though there s t i l l remained a background p o p u l a t i o n of n a n o f l a g e l l a t e s . On the east s i d e with g r e a t e r s a l i n i t y s t r a t i f i c a t i o n , the diatoms were somewhat reduced and there was an i n c r e a s e i n p h o t o s y n t h e t i c n a n o f l a g e l l a t e s and d i n o f l a g e l l a t e s . The c i l i a t e g r a z e r s a l s o i n c r e a s e d . In Transect 3 ( F i g . 27b), the c e n t r a l histogram denotes organisms at Stn 3b. S a l i n i t y s t r a t i f i c a t i o n i n c r e a s e d from west to east while temperature s t r a t i f i c a t i o n was g r e a t e s t i n 1 58 m i d - S t r a i t . The diatom biomass remained f a i r l y constant a c r o s s the S t r a i t without any response to the changes i n s t r a t i f i c a t i o n . P h o t o s y n t h e t i c n a n o f l a g e l l a t e s i n c r e a s e d with i n c r e a s i n g s a l i n i t y s t r a t i f i c a t i o n as d i d t h e i r g r a z e r s . Transect 4 ( F i g . 27c) saw diatoms most abundant on the west s i d e and l e a s t abundant m i d - S t r a i t . S t r a t i f i c a t i o n g e n e r a l l y i n c r e a s e d from west to e a s t . The diatoms d i d not seem to show any s p e c i f i c response. The p h o t o s y n t h e t i c n a n o f l a g e l l a t e biomass became g r e a t e r with i n c r e a s i n g s t r a t i f i c a t i o n as d i d the biomass of p h o t o s y n t h e t i c d i n o f l a g e l l a t e s . Along Transect 5 s t r a t i f i c a t i o n d i d not change g r e a t l y except at Stn 4d where s a l i n i t y d i f f e r e n c e s were markedly h i g h e r . Diatom biomass was l a r g e i n m i d - S t r a i t . The n a n o f l a g e l l a t e s were more abundant on the east s i d e and may have been responding to higher s a l i n i t y s t r a t i f i c a t i o n . T r ansect 6a ( F i g . 28a) again e x h i b i t s a decrease i n s t r a t i f i c a t i o n from D e s o l a t i o n Sound to the i n l e t s j u n c t i o n . T h i s decrease was accompanied by a decrease i n h e t e r o t r o p h i c d i n o f l a g e l l a t e biomass, though P r o t o p e r i d i n i u m remained constant, and an i n c r e a s e i n diatoms and p h o t o s y n t h e t i c n a n o f l a g e l l a t e s . Within the complex (Transect 6b, F i g . 28b), s a l i n i t y s t r a t i f i c a t i o n was very low whereas that of temperature (AT = 7.5-9.5°C) was q u i t e marked and seemed to dominate the d e n s i t y s t r a t i f i c a t i o n . Diatoms i n L a n c e l o t I n l e t remained as abundant as at the j u n c t i o n while Okeover I n l e t ' s diatoms were reduced to a q u a r t e r of the j u n c t i o n ' s diatom biomass. S t r a t i f i c a t i o n 159 p a t t e r n s seemed to have l i t t l e e f f e c t on t h i s d i s t r i b u t i o n . There was g r e a t e r h e t e r o t r o p h i c d i n o f l a g e l l a t e biomass i n Okeover which may have been r e s p o n s i b l e f o r the diatom d e c l i n e . N a n o f l a g e l l a t e s remained constant i n the two i n l e t s , and the bimodal occurrence of M. rubrum was once again seen. 160 F i g u r e s 25a-c. S t r a t i f i c a t i o n contours f o r the northern S t r a i t of Georgia, August 12-13, 1986. a. Temperature d i f f e r e n c e (AT = °C) between the s u r f a c e and 20 m. b. S a l i n i t y d i f f e r e n c e (AS = ppt) between the s u r f a c e and 20 m. c. Den s i t y d i f f e r e n c e (AD = at) between the s u r f a c e and 20 m. F i g u r e s 2 6 a - i . Organismal biomass (ng O m l ~ 1 ) contours f o r the northern S t r a i t of Georgia, August 12-13, 1986. a. Diatoms b. P r o t o p e r i d i n i u m spp. c. Other h e t e r o t r o p h i c d i n o f l a g e l l a t e s d. P h o t o s y n t h e t i c d i n o f l a g e l l a t e s e. P h o t o s y n t h e t i c n a n o f l a g e l l a t e s f. H e t e r o t r o p h i c c i l i a t e s g. P h o t o s y n t h e t i c f l a g e l l a t e s h. Mesodinium rubrum i . H e t e r o t r o p h i c n a n o f l a g e l l a t e s 162 163 F i g u r e 26. Augus t B iomass (ngC-mf 1) d.Photo-Dinos e.Photo-Nanos f . C i l i a t e s 164 F i g u r e 26. Augus t B iomass (ng C-ml"1) g.Photo-Flags h.Mesodinium i.Hetero-Nanos 165 F i g u r e s 27a-d. Temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n along t r a n s e c t s i n the northern S t r a i t of Georgia from west ( l e f t = Vancouver I s l a n d s i d e ) to east ( r i g h t = mainland s i d e ) , August 12-13, 1986. Each s t r a t i f i c a t i o n p l o t shows values f o r the s t a t i o n s . When data f o r a p a r t i c u l a r s t a t i o n are m i s s i n g , the curves may be i n t e r r u p t e d . Below the s t r a t i f i c a t i o n p l o t s l i e histograms f o r the 3 s t a t i o n s b i o l o g i c a l l y enumerated. Organismal codes are as f o l l o w s : d i a t o = diatoms pdino = p h o t o s y n t h e t i c d i n o f l a g e l l a t e s hdino = h e t e r o t r o p h i c d i n o f l a g e l l a t e s pnano = p h o t o s y n t h e t i c n a n o f l a g e l l a t e s hnano = h e t e r o t r o p h i c n a n o f l a g e l l a t e s p f l a g = p h o t o s y n t h e t i c f l a g e l l a t e s mesod = Mesodinium rubrum c i l i a = h e t e r o t r o p h i c c i l i a t e s a. Transect 1 b. Transect 3 c. Transect 4 d. Transect 5 F i g u r e s 28a-b. Temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n along t r a n s e c t s i n Malaspina Complex, August 12-13, 1986. Histogram codes are as above. a. Transect 6a: Malaspina I n l e t from D e s o l a t i o n Sound ( l e f t ) to the i n l e t s j u n c t i o n ( r i g h t ) . b. Transect 6b: Okeover I n l e t ( l e f t ) and L a n c e l o t I n l e t ( r i g h t ) with the j u n c t i o n i n the middle. 166 F i g u r e 27. Northern S t r a i t of Georgia. August 12-13. a. Tranaect 1 O O O O O B Q T J O O O O O O B O X J O O O O O O B C S T J O ^ C C C H B O C J J - P C C C ^ B O C 4 V 4 J C C C « 4 0 O C H L ' D T J C ' f ' - B C H L T J T J C H V B C W L B TJ C »< »• « C T J Q . J = Q . Q . O Q . B X : T J Q . J = Q . O . U O . B X : T] tt C 1 Q U II B C b. Transect 3 • i B +» r-l O Q 8"L § E CO cn c 10 [• 9 B 7 6 5 O co i B •P r-t D a 3 r 2 H 6 5 < 4 ? B 3 S a a 2 500 r 50 5 i mm I O O O O O B O T J O B O « - l « - f B i - t i - « B B • 4 C - < t J T J C « - i « - 0 C D a c a a u a B r O O O O O 0 O I 1 3 O 4 J 4 » C C C « 4 B O C B O « 4 - r l B i - I M B B H L T J T J C » " - J C - a a . J C a a . u a 6 c O O O O O B D T J O 4 » 4 i C C C ^ B O C B O * 4 « - I S r 4 > - t B B t i a c a a u a e c 1 6 7 F i g u r e 27. Northern S t r a i t of Georgia. August 12-13. c. Transect 4 • i o 4J r-l O Q i E O O CD C 500 50 5 1 234 I JZL 0 0 0 0 0 0 0 0 0 • P - P C C C - H O O C 0 O « 4 * 4 O i ~ l r - f B 0 H t . T J T J C ' r t ' - C I C • o a c a a u a B C 0 0 0 0 0 0 0 0 0 J P J P C C C - - I 0 O C 0 O < r l - H 0 i - « r - f 0 0 •rl L TJ TJ C «< * - 0 C o a c a a u a e x : o o o o o o a o o 4 J J J J C C C < 1 0 O C 0 O « - l w 4 0 l H l - I B 0 • r l L T J T J C - f V O C o a . j c a a u a . B j c d. Transect 5 1 0 4J 10 9 h B 7 6 5 O cn 1 0 ** rt 0 a / \ • \ • N / \ 5 < 4 ? 0 3 s 0 Q J 2 S 1 c 0 E o U « cn CD c 5001 50 i 5 I I o o o o o o a o o * > 4 J C C C < H 0 O C 0 O * 4 « 4 O r 4 r - I B 0 * * C " O O C * « " » - 0 C n a c a a u a B r o o o o o o a o o • p - v c c c - n a o c 0 O < n « 4 0 r 1 r 1 M 0 u a c a a u a B c o o o o o o a o o • * j > + > c c c * 4 e o c o o v 4 « , « 0 ' - > t - i B a « « c . o o c * « « - o c o a c a a u a B C 168 Figure 28. Malaspina Complex, August 12-13 a . T r a n s e c t 6a - M a l a s p i n a 10 9 B 7 6 5 500 50 5 co i o *t i-i a a 4 3 2 1 1 6 • 5 < • 4 a t e +» • 3 rial • 2 0 24 I 12 /ANl7^N]/AXy> 0 0 0 0 0 0 0 0 0 4 - > * > C C C « - l 0 O C 0 O < 1 < t 0 r - t i - t B 0 » - I C ' 0 " O C " - « » - f f l C u a . c a a . u a . B x : 0 0 0 0 0 0 0 0 0 • U - M C C C ^ O O C 0 O v 4 « 4 0 i - * i - i n o « - t C O O C * 4 « - 0 C o a x : a a u a B J C b. T r a n s e c t 6b - Okeover fi L a n c e l o t 500 r o o o o o o a o o 4 J . P C C C < r 4 0 O C 0 o « « < - i 0 i - i ' - t a 0 « 4 C O O C * 4 « - 0 C o a c a a u a B c o o o o o o a o o • f - P C C C * 4 0 0 C O O « - l » * 0 r - » r - « n O « 4 C O O C * 4 « - O C o a c a a u a B c o o o o o o a o o * » * » C C C « - I 0 O C O O < r 4 « 4 O r - l l - 4 B 0 * l t . O O C * * " » - 0 C o a c a a u a B j c 169 3.2.5 September H o r i z o n t a l d i s t r i b u t i o n maps of s t r a t i f i c a t i o n i n September are presented i n F i g s . 29a-c. Temperature s t r a t i f i c a t i o n was remarkably s i m i l a r (AT=5°C) throughout the S t r a i t . There was an unusual l e n s of high s a l i n i t y s t r a t i f i c a t i o n o f f Cape Lazo which appeared to be coming from the southern S t r a i t . Otherwise, the northern end of the NSG showed the highest values (4 p p t ) , perhaps due to i n t r u s i o n of l e s s s a l i n e s u r f a c e water from D e s o l a t i o n Sound and S u t i l Channel. Density s t r a t i f i c a t i o n tended to f o l l o w s a l i n i t y and was g r e a t e s t near D e s o l a t i o n Sound (4 at u n i t s ) . There was an d i s r u p t i o n i n s t r a t i f i c a t i o n near the t i d a l j e t (NW) which d i d not seem to be i n f l u e n c i n g the main body of the NSG. S t r a t i f i c a t i o n had been eroded throughout the S t r a i t s i n c e August, probably due to heat l o s s to the atmosphere at n i g h t . S u r p r i s i n g l y , the g r e a t e s t d e n s i t y s t r a t i f i c a t i o n o c c u r r e d i n the t i d a l l y mixed no r t h due to a seeming i n t r u s i o n of l e s s s a l i n e water from the northern passages. Organismal biomass was comprised of diatoms (57.8%), p h o t o s y n t h e t i c n a n o f l a g e l l a t e s (23.3%), h e t e r o t r o p h i c c i l i a t e s (10.7%), h e t e r o t r o p h i c d i n o f l a g e l l a t e s (3.4%), p h o t o s y n t h e t i c d i n o f l a g e l l a t e s (2.9%), p h o t o s y n t h e t i c f l a g e l l a t e s (1.0%), h e t e r o t r o p h i c n a n o f l a g e l l a t e s (0.6%), and p h o t o s y n t h e t i c c i l i a t e s ( 0 .3%). The diatoms ( F i g . 30a) had a d e f i n i t e p r e f e r e n c e f o r the west s i d e , reaching a peak abundance o f f Cape Lazo. The h e t e r o t r o p h i c d i n o f l a g e l l a t e s ( F i g . 30c) other than P r o t o p e r i d i n i u m a l s o p r e f e r r e d the west s i d e and were probably 170 gr a z i n g diatoms. A s s o c i a t e d with the s t r a t i f i e d waters of the north were p h o t o s y n t h e t i c d i n o f l a g e l l a t e s ( F i g . 30d) which appeared to a t t r a c t P r o t o p e r i d i n i u m g r a z e r s ( F i g . 30b). The d i s t r i b u t i o n s of p h o t o s y n t h e t i c n a n o f l a g e l l a t e s ( F i g . 30e) and t h e i r g r a z e r s , the h e t e r o t r o p h i c c i l i a t e s ( F i g . 3 0 f ) , were most abundant on the east s i d e . I n t e r e s t i n g l y , i n between these two d i s t r i b u t i o n a l p a t t e r n s l a y the ph o t o s y n t h e t i c f l a g e l l a t e s ( F i g . 30g) and M. rubrum ( F i g . 30h), which formed m i d - S t r a i t c o n c e n t r a t i o n s . At no other time were these groups so g e o g r a p h i c a l l y separated, e s p e c i a l l y the diatoms and n a n o f l a g e l l a t e s . Transect 1 ( F i g . 31a) showed v i r t u a l l y constant s a l i n i t y s t r a t i f i c a t i o n a c r o s s the S t r a i t (except f o r the h i g h l y s t r a t i f i e d l e n s at 1b). Temperature and d e n s i t y s t r a t i f i c a t i o n i n c r e a s e d from west to east. On the western s i d e , diatoms dominated completely but v i r t u a l l y disappeared by m i d - S t r a i t . The regimes of these two s t a t i o n s were n e a r l y i d e n t i c a l so that i t seems u n l i k e l y that s t r a t i f i c a t i o n was the major s e l e c t i n g f o r c e . The m i d - S t r a i t and ea s t e r n s t a t i o n s were dominated by ph o t o s y n t h e t i c n a n o f l a g e l l a t e s . Although the l a t t e r s t a t i o n was more s t r a t i f i e d , the n a n o f l a g e l l a t e biomass remained c o n s t a n t . C i l i a t e biomass decreased. Transect 3 ( F i g . 31b) temperature s t r a t i f i c a t i o n was minimal m i d - S t r a i t . The diatoms dominated the west s i d e and were p r o g r e s s i v e l y reduced eastwards rather than ending a b r u p t l y as occurred along Transect 1. The n a n o f l a g e l l a t e s became the biomass dominants on the east s i d e . 171 T r a n s e c t 4 ( F i g . 31c) a l s o showed even s t r a t i f i c a t i o n from west to e a s t . Diatoms decreased from west to east while the n a n o f l a g e l l a t e s i n c r e a s e d . T r a n s e c t 5 ( F i g . 3ld) shows a t r e n d of i n c r e a s i n g d e n s i t y s t r a t i f i c a t i o n from west to east accompanied by a decrease i n diatoms and an i n c r e a s e i n n a n o f l a g e l l a t e s . Along t h i s t r a n s e c t , changes i n s t r a t i f i c a t i o n were g r e a t e s t . Along Transect 6a ( F i g . 32a) there was a breakdown of s t r a t i f i c a t i o n i n Malaspina I n l e t . The most notable biomass d i f f e r e n c e was a great i n c r e a s e i n M. rubrum and a r e d u c t i o n i n the h e t e r o t r o p h i c c i l i a t e s . Along Transect 6b ( F i g . 32b) there was l i t t l e s t r a t i f i c a t i o n . In Okeover I n l e t M. rubrum became as important a biomass dominant as the diatoms sometimes achieved. T h i s M. rubrum bloom r a d i a t e d from here but was q u i c k l y reduced as i t approached L a n c e l o t I n l e t . In L a n c e l o t , the diatoms were the most important c o n t r i b u t o r s to biomass. 172 F i g u r e s 29a-c. S t r a t i f i c a t i o n contours f o r the northern S t r a i t of Georgia, September 16-17, 1986. a. Temperature d i f f e r e n c e (AT = °C) between the s u r f a c e and 20 m. b. S a l i n i t y d i f f e r e n c e (AS = ppt) between the s u r f a c e and 20 m. c. D e n s i t y d i f f e r e n c e (AD = at) between the s u r f a c e and 20 m. F i g u r e s 3 0 a - i . Organismal biomass (ng C«ml~ 1) contours f o r the northern S t r a i t of Georgia, September 16-17, 1986. a. Diatoms b. P r o t o p e r i d i n i u m spp. c. Other h e t e r o t r o p h i c d i n o f l a g e l l a t e s d. P h o t o s y n t h e t i c d i n o f l a g e l l a t e s e. P h o t o s y n t h e t i c n a n o f l a g e l l a t e s f. H e t e r o t r o p h i c c i l i a t e s g. P h o t o s y n t h e t i c f l a g e l l a t e s h. Mesodinium rubrum i . H e t e r o t r o p h i c n a n o f l a g e l l a t e s 175 177 F i g u r e s 3 l a - d . Temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n along t r a n s e c t s i n the northern S t r a i t of Georgia from west ( l e f t = Vancouver I s l a n d s i d e ) to east ( r i g h t = mainland s i d e ) , September 16-17, 1986. Each s t r a t i f i c a t i o n p l o t shows valu e s f o r the s t a t i o n s . When data f o r a p a r t i c u l a r s t a t i o n are m i s s i n g , the curves may be i n t e r r u p t e d . Below the s t r a t i f i c a t i o n p l o t s l i e histograms for the 3 s t a t i o n s b i o l o g i c a l l y enumerated. Organismal codes are as f o l l o w s : d i a t o = diatoms pdino = p h o t o s y n t h e t i c d i n o f l a g e l l a t e s hdino - h e t e r o t r o p h i c d i n o f l a g e l l a t e s pnano = p h o t o s y n t h e t i c n a n o f l a g e l l a t e s hnano = h e t e r o t r o p h i c n a n o f l a g e l l a t e s p f l a g = p h o t o s y n t h e t i c f l a g e l l a t e s mesod = Mesodinium rubrum c i l i a = h e t e r o t r o p h i c c i l i a t e s a. Transect 1 b. T r a n s e c t 3 c. T r a n s e c t 4 d. Transect 5 F i g u r e s 32a-b. Temperature, s a l i n i t y , and d e n s i t y s t r a t i f i c a t i o n along t r a n s e c t s i n Malaspina Complex, September 16-17, 1986. Histogram codes are as above. a. Transect 6a: Malaspina I n l e t from D e s o l a t i o n Sound ( l e f t ) to the i n l e t s j u n c t i o n ( r i g h t ) . b. Transect 6b: Okeover I n l e t ( l e f t ) and L a n c e l o t I n l e t ( r i g h t ) with the j u n c t i o n i n the middle. 178 F i g u r e 31. Northern S t r a i t of Georgia. September 16-17. a . T r a n s e c t 1 0 0 0 0 0 0 0 X 3 0 O O O O O 0 O T 3 O 0 0 0 0 0 0 0 x 1 0 4 J 4 J C C C * 4 0 O C 4 * 4 J C C C * 4 0 O C 4 - » 4 J C C C « - « O D C 0 O « - l « 4 0 f - > i - I B 0 0 O « - l » « 0 . - » i - » B 0 0 D * 4 * 4 0 > - l i - t 0 0 « « C . T 3 X J C « 4 * - 0 C H C T J U C ^ I - a i C « 1 L D D C ' I V « C T 3 a c Q . C 3 . U a B x : u a x r a a u a s x : n a c a . a . u a B x : b. T r a n s e c t 3 O O O O O 0 O X I O 0 0 0 0 0 0 0 - 0 0 0 0 0 0 0 0 0 ) 1 1 0 + > - P C C C « - < B O C - P - U C C C ^ O O C - P - P C C C - ^ I O O C B O « - l < - I O i - l f - I O D a 0 O « - l « - f 0 r - l r 4 | ) 0 0 O « - t « - * 0 i - f i - > 0 0 « L D T ) C < < t - I I C H L t J T I C H V O C f t L U Q C H ^ g c - o a c a a u a e x : x i a c a a u a B c x i a x r a a u a B x : 179 F i g u r e 31. Northern S t r a i t of Georgia. September 16-17 c. Transect 4 i « • P r-» 0 a m -_ m p «-t cn CD C 500 r 50 h ~ 5 1 1 Q T ) O O O O O O 0 J P J ) J C C C " - I 0 O C 0 O * f « - < 0 r - t r - t a 0 o a c a a u a B j c 0 0 0 0 0 0 0 0 0 0 O « - t « - > O r - l r - I B 0 « - » C T 3 " O C * - « » - a > C - o a j c a a u o . e e o o o o o o a o o 4 J J P C C C " - « 0 O C O O * « * « 0 i - « r - l 0 O ^ C - O O C ^ ^ - O C •a ax: a a u a e x : d. Transect 5 t o *> r-» O Q % E O U m cn CD c 500 50 5 o o o o o o a o o • P J P C C C I O O C O O « - l « - l 0 r - 4 i - » B O « « e . o o c « « « - o c o a j c a a u a e c o o o o o o a o o J J J . P C C C « - f 0 O C O O - r 4 « 4 O l - 4 r 4 a 0 « - » C - O O C » « » - o e o a c a a u a B c o o o o o o a o o 4 J > 4 J > C C C < r * O O C o o « 4 « 4 O i - i f - i n 0 * I C O O C * « » - O C o a c a a u a B j c 180 Figure 32. Malaspina Complex. September 16-17 a. Transact 6a - Malaspina H I 0 4J r-l O Q w"7 0 — § ? o U to c 500 r 50 • i 5 O O O O O 0 O ) X 3 O . p - P C C C - H O O C 0 O « 4 « - I 0 r f r 4 0 0 H L H TJ c » • <a c x i a j r a a u a B j r I SI 1 O O O O O 0 D ) T I O 4 J 4 * C C C « 4 0 O C » * C . T 3 T 3 C * » » - 0 C - o a x z a a u a B c b. Transect 6b - Okeover G Lancelot l 0 4J r-« 0 Q 500 0 E 50 h o O CO c i 5 i EL O O O O O 0 O ) T J O • P - P C C C ^ B O C 0 O « - l « - l 0 i - f < - f 0 0 n a j r a a . u a . B x : 0 0 0 0 0 0 0 ) 1 3 0 • U * J C C C » « 0 O C 0 O « - l « 4 0 r - l f - 4 B 0 T i a j r a a u a B i r O O O O O 0 O I T 3 O - P 4 J C C C « - « 0 O C 0 O * 4 « - t 0 r - l < - * O 0 • H t X J X I C * l « - 0 C u a c a a u a B j r 181 3.3 MULTIPLE REGRESSION ANALYSIS 3.3.j_ S t a t i s t i c a l Background Multiple regression analysis i s c l e a r l y dealt with by Cooper and Weekes (1983), from which most of the following information i s taken. This analysis i s another multivariate technique; however, unlike canonical correlation analysis, there is a dependency implied. The dependent variable in the following analyses i s always the average biomass (transformed with natural logarithms) of some organism over the four depths sampled per station. Only one dependent variable is used at a time. The number of independent or explanatory variables, however, can be greater than one. The regression equation consists of two parts: a systematic component which explains the relationship, and a random component which cannot be observed but i s assumed to have a normal d i s t r i b u t i o n . Upon solution of a set of normal equations, the c o e f f i c i e n t s of the regression equation are determined and a model is created thus: y = b 0 + b,X! + b 2x 2 + . . . . bk«xk where y denotes a f i t t e d value based on the explanatory variables xk; and bk are the regression c o e f f i c i e n t s . There w i l l be k+1 regression c o e f f i c i e n t s (systematic parameters) for k explanatory variables as b 0 describes the y-intercept. The residuals of t h i s equation, which estimate values of the random component, can be calculated by subtracting f i t t e d values of Y from the o r i g i n a l l y observed values of Y. Each c o e f f i c i e n t (bk) expresses how much a p a r t i c u l a r 1 8 2 explanatory v a r i a b l e a f f e c t s the dependent v a r i a b l e , assuming that a l l other explanatory v a r i a b l e s remain f i x e d . When the systematic parameters of a r e g r e s s i o n have been c a l c u l a t e d , the hypothesis that a p a r t i c u l a r parameter i s equal to zero can be t e s t e d by c a l c u l a t i n g a t - r a t i o (bk/SE(bk)). I f the n u l l hypothesis i s t r u e , t has a d i s t r i b u t i o n based on ( n - k - 1 ) degrees of freedom. I f the c a l c u l a t e d t - r a t i o i s grea t e r than that determined f o r the n u l l h y p o thesis (bk= 0 ) at a c e r t a i n l e v e l of s i g n i f i c a n c e , the n u l l h ypothesis i s r e j e c t e d and bk i s s i g n i f i c a n t . I t i s standard p r a c t i c e to report e i t h e r the standard e r r o r s of the c o e f f i c i e n t s or t h e i r t - r a t i o s i n brackets below the r e g r e s s i o n e q u a t i o n . T h i s r e p o r t uses t - r a t i o s . The r e g r e s s i o n equation as a whole can be d e s c r i b e d by a m u l t i p l e c o r r e l a t i o n c o e f f i c i e n t R 2, which i n d i c a t e s the "goodness of f i t " of the r e l a t i o n s h i p . T h i s c o e f f i c i e n t i s b a s i c a l l y determined by the r a t i o of the e x p l a i n e d sum of squares (the sum of squared d e v i a t i o n s of the f i t t e d v a l u e s of Y around t h e i r mean) to the t o t a l sum of squares (sum of squared d e v i a t i o n s of the Y values around t h e i r mean). N a t u r a l l y , the c l o s e r the f i t t e d values are to the o r i g i n a l v a l u e s , the c l o s e r the above r a t i o i s to 1 and the b e t t e r the f i t . To t e s t whether the r e g r e s s i o n equation i s s i g n i f i c a n t , one t e s t s the n u l l h ypothesis that b, to bk are a l l equal to zero. To do so, the mean r e g r e s s i o n sum of squares ( r e g r e s s i o n sum of squares d i v i d e d by the degrees of freedom f o r the r e g r e s s i o n ) i s d i v i d e d by the mean r e s i d u a l sum of squares ( r e s i d u a l sum of 183 squares d i v i d e d by the degrees of freedom f o r the r e s i d u a l s ) to o b t a i n an F - r a t i o . The l a r g e r the r e g r e s s i o n SS r e l a t i v e to the r e s i d u a l SS, the grea t e r the F-value and the g r e a t e r the chance of r e j e c t i n g the n u l l h y p o t h e s i s . C r i t i c a l v a l u e s of the two-parameter F - d i s t r i b u t i o n can be looked up i n F - t a b l e s . The degrees of freedom are those f o r the r e g r e s s i o n SS and the r e s i d u a l SS. Often when one chooses a set of independent v a r i a b l e s , t h e i r u n i t s of measurement are q u i t e d i f f e r e n t from one another. S c a l e s which i n v o l v e l a r g e r u n i t s of measurement w i l l r e c e i v e r e g r e s s i o n c o e f f i c i e n t s of g r e a t e r magnitude and an unsuspected weighting. To a v o i d t h i s problem, a l l independent v a r i a b l e s were f i r s t s t a n d a r d i s e d (by s u b t r a c t i n g the mean and d i v i d i n g by the standard d e v i a t i o n ) so that they were comparable to each o t h e r . Another problem to a v o i d i s that of m u l t i c o l l i n e a r i t y which d e s c r i b e s the c o n d i t i o n when one or more of the explanatory v a r i a b l e s are c o r r e l a t e d with each other. U n f o r t u n a t e l y , t h i s c o n d i t i o n i s hard to a v o i d when using f i e l d d a ta. A f t e r v a r i o u s t r i a l runs on d i f f e r e n t data s e t s , f i v e of the most independent v a r i a b l e s (from each other) were decided upon. The f i r s t v a r i a b l e i s d e n s i t y s t r a t i f i c a t i o n , determined as the abs o l u t e d i f f e r e n c e i n sigma-t u n i t s from the s u r f a c e to 20 m. Second i s p y c n o c l i n e depth, determined as the depth at which a d e n s i t y change over 3 m was maximal. The t h i r d v a r i a b l e i s s u r f a c e temperature which was thought to be a good i n d i c a t o r of s e a s o n a l i t y . Fourth i s the average n i t r a t e c o n c e n t r a t i o n over the four depths sampled per s t a t i o n . The f i f t h v a r i a b l e i s an 184 estimate of g r a z i n g p r e s s u r e determined as Z phaeopigments/I c h l o r o p h y l l . T h i s measure was suggested by Lorenzen (1967) who found a d i r e c t r e l a t i o n s h i p between (no.copepods/Z c h l o r o p h y l l ) and (I phaeopigments/I c h l o r o p h y l l ) . A f t e r a r e g r e s s i o n model has been f i t t e d , one should check that the assumptions of m u l t i p l e r e g r e s s i o n have not been v i o l a t e d . A u s e f u l method i s to p l o t r e s i d u a l s a g a i n s t f i t t e d v a l u e s of Y. In theory, r e s i d u a l s are u n c o r r e l a t e d with f i t t e d v a l u e s so that the mean r e s i d u a l i s zero; however, how the r e s i d u a l s p a t t e r n themselves can be very i n f o r m a t i v e . I f r e s i d u a l s are p e r s i s t e n t l y negative or p o s i t i v e i n the middle of the range, a c u r v i l i n e a r r e l a t i o n s h i p has been modeled by a l i n e a r systematic component. One can t r y t r a n s f o r m a t i o n of the Y-values or perhaps i d e n t i f y and s p l i t the Y-values i n t o separate groups. Often r e s i d u a l s w i l l be more s c a t t e r e d away from the zero l i n e over part of the range, a c o n d i t i o n which i m p l i e s h e t e r o s c e d a s t i c i t y , i . e . , the random component does not have a constant v a r i a n c e . Should such a c o n d i t i o n occur, the model i s not i n v a l i d but the standard e r r o r s of the r e g r e s s i o n c o e f f i c i e n t s are gr e a t e r than they would otherwise be. Often h e t e r o s c e d a s t i c i t y occurs when some element of s i z e i s important so t h a t , f o r in s t a n c e , i n d i v i d u a l s which are l a r g e r e x h i b i t g r e a t e r v a r i a n c e . In t h i s study, s i z e i s r e l a t e d to biomass so that one would expect the v a r i a n c e of higher biomass o b s e r v a t i o n s to be g r e a t e r . I t i s q u i t e usual i n e c o l o g i c a l s t u d i e s to expect o u t l i e r s 185 i n the data. These show up as r e s i d u a l s f a r from the z e r o - l i n e of a r e s i d u a l p l o t , and can imply that the assumption that the random component has a normal d i s t r i b u t i o n i s i n v a l i d . In t h i s study, o u t l i e r s were a common event so that as a matter of convention, the r e s i d u a l s were s t a n d a r d i s e d (Studentized) and those val u e s l y i n g o u t s i d e the 95% c o n f i d e n c e i n t e r v a l of ± 1.96 standard d e v i a t i o n s from the mean (zero) were removed. The remaining o b s e r v a t i o n s were then put through the r e g r e s s i o n a g a i n , and where a l i n e a r f i t was i n d i c a t e d , no f u r t h e r adjustment was made. 3 .2«2 Regression Analyses The r e g r e s s i o n c o e f f i c i e n t s of the main organismal groups are presented as s t a r p l o t s i n F i g u r e 33. The l e n g t h of each ray w i t h i n a p l o t i s p r o p o r t i o n a l to the r e g r e s s i o n c o e f f i c i e n t s ' t - v a l u e s . Note that the s t a r p l o t s are not r e l a t i v e to each ot h e r . Numbers at the t e r m i n i of each ray, reading a n t i c l o c k w i s e from 0° (mid r i g h t p o s i t i o n ) , are the r e g r e s s i o n c o e f f i c i e n t s f o r xs = d e n s i t y s t r a t i f i c a t i o n (0°), xp = p y c n o c l i n e depth (72°), xt = s u r f a c e temperature (144°), xn = n i t r a t e (216°), and xg = g r a z i n g (288°). The r e g r e s s i o n equation f o r diatoms i s : Ln(biomass) = 3.08 - 0.511xs - 0.l06xp +1.02xt + 0.130xn - 1.07xg (19.3) (-2.08) (-0.541) (3.53) (0.589) (-5.54) F = 17.4 df = 5,69 R 2 = 0.558 With an F-value of 17.4, t h i s r e g r e s s i o n i s s i g n i f i c a n t at the 186 2.5% c r i t i c a l l e v e l . The t - v a l u e s f o r s t r a t i f i c a t i o n , s u r f a c e temperature, and g r a z i n g are a l l s i g n i f i c a n t at the 2.5% l e v e l . However, i f one p l o t s the S t u d e n t i z e d r e s i d u a l s a g a i n s t the f i t t e d Y-values ( f o r diatom biomass, F i g . 34a), one sees that the assumption of a l i n e a r r e l a t i o n s h i p between one or more v a r i a b l e s and the systematic component i s v i o l a t e d , i . e . , t h e i r appears to be a c u r v i l i n e a r r e l a t i o n s h i p . One can a l s o p l o t the observed diatom biomass a g a i n s t the o r i g i n a l independent v a r i a b l e s to ga i n some i n s i g h t i n t o the model. F i g u r e s 34b and 34c i l l u s t r a t e the two most h i g h l y s i g n i f i c a n t v a r i a b l e s , g r a z i n g and s u r f a c e temperature. The s i z e of the c i r c l e s are p r o p o r t i o n a l to the s i z e of the r e s i d u a l s so that f o r a given o b s e r v a t i o n one may see how w e l l i t i s ex p l a i n e d or p r e d i c t e d by the f i t t e d model. There i s a l a r g e range of observed diatom biomasses f o r the g r a z i n g pressure from 0.6 to 1.0. The low and hig h biomass groups are not p r e d i c t e d w e l l as t h e i r r e s i d u a l s are l a r g e , e s p e c i a l l y at lower biomass. T h i s v a r i a b l e , however, giv e s l i t t l e i n s i g h t and may only be r e f l e c t i n g the i n v e r s e of biomass as c h l o r o p h y l l a c o n c e n t r a t i o n i s the denominator of the g r a z i n g e x p r e s s i o n . Surface temperature g i v e s us a much b e t t e r c l u e . Note the d i s t i n c t c l u s t e r i n g of temperature v a l u e s . T h i s i s a r e s u l t of d i s c o n t i n u o u s sampling f o r a few days with months i n between. As mentioned e a r l i e r , s e a s o n a l i t y w i l l be s t r o n g l y i n d i c a t e d by su r f a c e temperature. The l a r g e s t r e s i d u a l s belong to biomass values f o r June when the system was very s t a b l e and the diatom presence minimal. 187 I f one now goes back to F i g u r e 34a one can recognise two d i s t i n c t s e t s of r e s i d u a l s , one f o r a low biomass group and one fo r a high biomass group. One can almost v i s u a l i s e two p a r a l l e l negative s l o p e s running through the r e s i d u a l s such that r o t a t i o n would b r i n g both slopes to zero, i . e . , to a c o n d i t i o n where the r e s i d u a l s are not c o r r e l a t e d with the f i t t e d v a l u e s . To achieve the s e p a r a t i o n , a l i n e d e s c r i b e d by [ r e s i d u a l s = - 5 / 6 ( f i t t e d values) + 2] was f i t by eye. A l l r e s i d u a l s l e s s than t h i s v e c t o r were pl a c e d i n a low biomass group while those g r e a t e r than the s e p a r a t i o n v e c t o r were p l a c e d i n a high biomass group. Regressions on these new groups were performed as d e s c r i b e d e a r l i e r and t h e i r r e g r e s s i o n equations are thus: Lndow biomass) = 1.17 - 0 . 1 9 2 X S + 0.0H7xp - 0.307xt - 0.0470xn - 0.00702xg (23.3) (-1.97) (0.199) (-2.15) (-0.494) (-0.113) F = 15.2 df = 5,28 R 2 = 0.730 Ln(high biomass) = 5.03 - 0.0949xs - 0.135xp + 0.40lxt - 0.0920xn - 0.0584xg (41.0) (-0.490) (-0.894) (2.02) (-0.618) (-0.362) F = 1.95 df = 5,30 R 2 = 0.246 F i g u r e 35 presents the s t a r p l o t s of the new r e g r e s s i o n c o e f f i c i e n t s which have changed from the o r i g i n a l diatom p l o t . G r azing i s now the l e a s t s i g n i f i c a n t f a c t o r i n both new r e g r e s s i o n s , which suggests that t h i s v a r i a b l e i s h i g h l y a r t i f i c i a l . The lower biomass group i s s t i l l s i g n i f i c a n t l y d e s c r i b e d by s u r f a c e temperature (p < 0.025) and s t r a t i f i c a t i o n (p < 0.05). The r e s i d u a l s p l o t ( F i g . 36a) i n d i c a t e s a l i n e a r r e l a t i o n s h i p though there i s a problem with h e t e r o s c e d a s t i c i t y 188 (Cooper & Weekes, 1983) which means the v a r i a n c e of the random component i s not equal. F i g u r e s 36b and c show that diatom biomass decreases with i n c r e a s i n g s u r f a c e temperature and d e n s i t y s t r a t i f i c a t i o n . Here we are embodying the essence of seasonal s t r a t i f i c a t i o n and i t s u l t i m a t e r e d u c t i o n of diatom biomass. Biomass val u e s i n the 8-9°C s p r i n g waters may be pre-bloom, which though low, are s t i l l higher that the val u e s of the summer biomass. From a l l i n d i c a t i o n s , however, there i s a suggestion that there may not have been a s p r i n g bloom. The r e g r e s s i o n f o r the higher biomass diatoms ( F i g s . 37a-c) i s not s i g n i f i c a n t at the 5% l e v e l (because F = 1.95 with 5,30 d f ) . The only v a r i a b l e d e s c r i b i n g t h i s biomass s i g n i f i c a n t l y i s s u r f a c e temperature (p < 0.05) which has a p o s i t i v e e f f e c t ( F i g . 37b). P h o t o s y n t h e t i c d i n o f l a g e l l a t e s have a very s i g n i f i c a n t r e g r e s s i o n equation (p < 0.025): Ln(biomass) = 1.65 + 0.352xs - 0.0820xp + 0.176xt - 0.308xn - 0.141xg (28.6) (3.92) (-1.16) (1.66) (-3.85) (-2.02) F = 34.9 df = 5,66 R 2 = 0.726 The r e g r e s s i o n c o e f f i c i e n t s f o r s t r a t i f i c a t i o n (p < 0.025), s u r f a c e temperature (p < 0.10), n i t r a t e (p < 0.025), and g r a z i n g (p < 0.025) are a l l c o n t r i b u t i n g to the p r e d i c t i o n of d i n o f l a g e l l a t e biomass. From the p l o t t e d r e s i d u a l s ( F i g . 38a), one can see that the r e g r e s s i o n i s a f a i r l y good l i n e a r f i t though h e t e r o s c e d a s t i e i t y i s apparent and probably unavoidable i n phytoplankton data. 189 S t r a t i f i c a t i o n ( F i g . 38b), which has long been recognised as a s e l e c t i n g f o r c e f o r d i n o f l a g e l l a t e s , was the best p r e d i c t o r . R e l a t e d to s t r a t i f i c a t i o n i s a decrease i n n i t r a t e , F i g . 38c showing that biomass i s higher at lower n i t r a t e s . There i s a c t u a l l y l i t t l e c o l l i n e a r i t y between s t r a t i f i c a t i o n and n i t r a t e (-0.21), which suggests that these two s e l e c t i n g f o r c e s are a c t i n g independently. Qu i t e p o s s i b l y , however, there may be a simple c o r r e l a t i o n i n that as s e a s o n a l i t y advances n i t r a t e s tend to be reduced by phytoplankton growth so that i f d i n o f l a g e l l a t e s i n c r e a s e with s e a s o n a l i t y , they w i l l appear to be dependent on d e c r e a s i n g n i t r a t e . The h e t e r o t r o p h i c d i n o f l a g e l l a t e r e g r e s s i o n equation i s : Ln(biomass) = 2.41 + 0.173xs - 0.l08xp + 0.141xt + 0.0886xn + 0.00224xg (34.8) (1.64) (-1.28) (1.13) (0.923) (0.0262) F = 4.18 df = 5,67 R 2 = 0.238 With an F - r a t i o of 4.18, t h i s r e g r e s s i o n i s s i g n i f i c a n t at the 2.5% l e v e l ; however, only the s t r a t i f i c a t i o n c o e f f i c i e n t i s s i g n i f i c a n t (p < 0.10). The r e s i d u a l s ( F i g . 39a) show no c o r r e l a t i o n with the f i t t e d v a l u e s which i n d i c a t e s a l i n e a r r e l a t i o n s h i p . At low s t r a t i f i c a t i o n values ( F i g . 39b), biomass i s extremely v a r i a b l e and probably i s independent of s t r a t i f i c a t i o n . There i s a set of l a r g e r e s i d u a l s at low s t r a t i f i c a t i o n and low biomass which, i f removed, c o u l d c o n c e i v a b l y make t h i s c o e f f i c i e n t not s i g n i f i c a n t l y d i f f e r e n t from z e r o . The p y c n o c l i n e depth ( F i g . 39c) has the next g r e a t e s t 190 e f f e c t but i s not s i g n i f i c a n t . The group " h e t e r o t r o p h i c d i n o f l a g e l l a t e s " i s mostly comprised of two very d i f f e r e n t organisms: Gyrodinium, which i s a phagotroph, and P r o t o p e r i d i n i u m , which i s a diatom grazer r e l y i n g on e x t r a c e l l u l a r d i g e s t i o n . T h e r e f o r e , these two organisms were each regressed on the f i v e independent v a r i a b l e s and t h e i r r e g r e s s i o n c o e f f i c i e n t s are d i s p l a y e d i n F i g u r e 40. The r e g r e s s i o n equation f o r Gyrodinium i s : Ln(biomass) = 1.84 + 0.449xs + 0.000l08xp - 0.233xt + 0.239xn + 0.0279xg (2.01) (3.23) (0.000970) (-1.41) (1.86) (0.248) F = 4.65 df = 5,70 R 2 = 0.250 which i s s i g n i f i c a n t at the 2.5% l e v e l . S i g n i f i c a n t c o e f f i c i e n t s are s t r a t i f i c a t i o n (p < 0.025), s u r f a c e temperature (p < 0.10), and n i t r a t e (p < 0.05). F i g u r e 41a shows a f a i r l y l i n e a r r e l a t i o n though h e t e r o s c e d a s t i e i t y may be a problem. Gyrodinium i s the organism w i t h i n " h e t e r o t r o p h i c d i n o f l a g e l l a t e s " which i s most p o s i t i v e l y a f f e c t e d by s t r a t i f i c a t i o n ( F i g . 41b). Gyrodinium i n c r e a s e s with i n c r e a s i n g n i t r a t e s ( F i g . 41c) as w e l l as with d e c r e a s i n g temperature, both i n d i c a t i n g a p r e f e r e n c e f o r an e a r l i e r season (e.g., M a r c h - A p r i l ) . The P r o t o p e r i d i n i u m r e g r e s s i o n equation i s : Ln(biomass) = 1.19 - 0.0200xs - 0.0406xp + 0.527xt - 0.116xn - 0.204xg (30.0) (-0.324) (-0.836) (7.25) (-2.09) ( - 4 . 2 1 ) F = 63.4 df = 5,67 R 2 = 0.825 T h i s i s very s i g n i f i c a n t (p < 0.025). Three of the c o e f f i c i e n t s are a l s o s t r o n g l y s i g n i f i c a n t : s u r f a c e temperature (p < 0.025), 191 g r a z i n g (p < 0.025), and n i t r a t e (p < 0.025). F i g u r e 42a g i v e s the S t u d e n t i z e d r e s i d u a l s which e x h i b i t no r e l a t i o n to the f i t t e d v alues but do show h e t e r o s c e d a s t i c i t y . F i g u r e 42b shows a very s t r o n g and c l e a r r e l a t i o n between s u r f a c e temperature and biomass. T h i s d i n o f l a g e l l a t e i s e i t h e r responding to temperatures or to some other form of seasonal v a r i a b l e . Because there was a n o n - l i n e a r or d i s c o n t i n u o u s response by diatoms to s u r f a c e temperatures, these diatom g r a z e r s as a group are o b v i o u s l y not completely dependent on diatoms f o r s u r v i v a l . Perhaps i n June when diatom abundance was minimal, s p e c i e s of P r o t o p e r i d i n i u m , which graze d i n o f l a g e l l a t e s and/or n a n o f l a g e l l a t e s , were dominant. Gra z i n g ( F i g . 42c) i s a l s o a b i g f a c t o r , with P r o t o p e r i d i n i u m d e c r e a s i n g with i n c r e a s i n g grazer p r e s s u r e . I f one r e f e r s back to the diatom r e g r e s s i o n s , one may r e c a l l that t h i s index seemed h i g h l y a r t i f i c i a l and perhaps i s r e f l e c t i n g simply the i n v e r s e of diatom biomass. A p p l i e d to t h i s s i t u a t i o n , the r e g r e s s i o n may be s t a t i n g t h a t Protoper i d i n i u m biomass i n c r e a s e s with diatom biomass. The r e g r e s s i o n equation f o r p h o t o s y n t h e t i c n a n o f l a g e l l a t e s i s : Ln(biomass) = 3.34 - 0.155xs + 0.0565xp + 0.236xt - 0.00748xn - 0.0879xg (70.6) (-2.15) (0.982) (2.76) (-0.0113) (-1.54) F = 4.53 df = 5,68 R 2 = 0.250 With an F - r a t i o of 4.53, the equation i s s i g n i f i c a n t at the 2.5% l e v e l . The s i g n i f i c a n t c o e f f i c e n t s are s u r f a c e temperature (p < 0.025), s t r a t i f i c a t i o n (p < 0.025), and g r a z i n g (p < 0.10). 192 F i g u r e 43a confirms the assumption of l i n e a r i t y , though the v a r i a n c e of the random component does not stay c o n s t a n t . D e s p i t e the d i s c o n t i n u o u s nature of the temperature data ( F i g . 43b), there appears to be a smooth upward tr e n d with i n c r e a s i n g temperature. I n c r e a s i n g s t r a t i f i c a t i o n ( F i g . 43c) decreases n a n o f l a g e l l a t e biomass, but judging by the s c a t t e r i n the p o i n t s as well as the r e s i d u a l s , i t i s hard to be convinced of t h i s t r e n d . I f one r e c a l l s , the n a n o f l a g e l l a t e d i s t r i b u t i o n changes with s e a s o n a l i t y or diatom abundance. During the f i r s t three sampling p e r i o d s , these organisms p r e f e r r e d the t i d a l l y - m i x e d n o r t h of the NSG. In August and September, diatoms were q u i t e abundant and themselves p r e f e r r e d the t i d a l l y - m i x e d north and west. The n a n o f l a g e l l a t e s were s h i f t e d to e a s t e r n waters where s t r a t i f i c a t i o n was h i g h e r . There seems to be some c o m p e t i t i v e e x c l u s i o n o c c u r r i n g . T h e r e f o r e , i t i s not s u r p r i s i n g to see such s c a t t e r i n the data. The m a j o r i t y of the n a n o f l a g e l l a t e biomass i s dominated by the two groups Chrysochromulina and cryptomonads. O c c a s i o n a l l y , T e t r a s e l m i s would c o n t r i b u t e a s i g n i f i c a n t percentage of the biomass i n i s o l a t e d a r e a s . These three groups were put through the m u l t i p l e r e g r e s s i o n s s e p a r a t e l y as dependent v a r i a b l e s , the independent v a r i a b l e s remaining as above. Only the r e g r e s s i o n f o r Chrysochromulina was s i g n i f i c a n t : Ln(biomass) = 2.64 - 0.239xs + 0.149xp + 0.392xt + 0.0634xn - 0.176xg (40.8) (-2.38) (1.82) (3.36) (0.703) (-2.24) F = 5.93 df = 5,68 R 2 = 0.304 Most of the v a r i a b l e s are s i g n i f i c a n t p r e d i c t o r s of 193 Chrysochromulina biomass: s t r a t i f i c a t i o n (p < 0.025), p y c n o c l i n e depth (p < 0.05), s u r f a c e temperature (p < 0.025), and g r a z i n g (p < 0.025). The f i r s t two v a r i a b l e s together i n d i c a t e that t h i s prymnesiophyte p r e f e r s w i n t e r - l i k e c o n d i t i o n s when s t r a t i f i c a t i o n i s low and the p y c n o c l i n e i s deeper. However, the temperature v a r i a b l e says t h i s organism p r e f e r s summer c o n d i t i o n s and so one would expect Chrysochromulina to be most abundant i n summer in areas where s t r a t i f i c a t i o n has been upset by some turbulence mechanism such as t i d a l streaming. Grazing p r e s s u r e , as d e f i n e d , reduces the abundance of t h i s organism; however, e a r l i e r we saw that the g r a z i n g term may be r e f l e c t i n g the i n v e r s e of diatom biomass. I t i s c u r i o u s that Chrysochromulina i s i n v e r s e l y c o r r e l a t e d with diatoms when they both p r e f e r l e s s s t r a t i f i e d waters. The answer may i n v o l v e the depth of the p y c n o c l i n e . Chrysochromulina was shown above to p r e f e r deeper p y c n o c l i n e s . T h i s i n c r e a s e d depth of mixing may be s u f f i c i e n t to suppress diatom growth. P r o v i d i n g a d v e c t i o n r a t e s to depth are not too g r e a t , Chrysochromulina has an advantage i n being m o t i l e and thus remaining i n the upper euphotic zone. The cryptomonad r e g r e s s i o n c o e f f i c i e n t s show s i m i l a r trends to those of Chrysochromulina; however, the r e g r e s s i o n equation as a whole i s not s i g n i f i c a n t and i s t h e r e f o r e not presented. The h e t e r o t r o p h i c n a n o f l a g e l l a t e s , c o n s i s t i n g mostly of c h o a n o f l a g e l l a t e s , e x h i b i t a s i g n i f i c a n t r e g r e s s i o n equation thus: Ln(biomass) = 0.421 - 0.0725xs + 0.0l21xp + 0.l86xt - 0.0169xn - 0.0572xg (15.5) (-1.73) (0.363) (3.85) (-0.461) (-1.74) 194 F = 8.95 df = 5,68 R 2 = 0.397 C o e f f i c i e n t s of s i g n i f i c a n c e are s u r f a c e temperature (p < 0.025), g r a z i n g (p < 0.05), and s t r a t i f i c a t i o n (p < 0.05). The S t u d e n t i z e d r e s i d u a l s ( F i g . 44a) show a f a i r l y l i n e a r r e l a t i o n s h i p though h e t e r o s c e d a s t i e i t y may be a problem. Surface temperature ( F i g . 44b) e l i c i t s a p o s i t i v e response from these n a n o f l a g e l l a t e s . Therefore one might assume t h a t they i n c r e a s e i n abundance d u r i n g the summer. S t r a t i f i c a t i o n ( F i g . 44c) causes a d e c l i n e i n biomass though the t r e n d i s not r e a d i l y apparent. Higher biomass values are not w e l l p r e d i c t e d by the model as the s i z e of t h e i r r e s i d u a l s i s l a r g e . P h o t o s y n t h e t i c f l a g e l l a t e s are s i g n i f i c a n t l y d e s c r i b e d by the r e g r e s s i o n equation: Ln(biomass) = 1.03 + 0.435xs - 0.l72xp - 0.l20xt - 0.251xn + 0.143xg (13.2) (3.62) (-1.75) (-0.871) (-2.33) (1.52) F = 9.38 df = 5,65 R 2 = 0.419 Of s i g n i f i c a n c e are the c o e f f i c i e n t s f o r s t r a t i f i c a t i o n (p < 0.025), n i t r a t e (p < 0.025), p y c n o c l i n e depth (p < 0.05), and g r a z i n g (p < 0.10). F i g u r e 45a shows that the r e l a t i o n s h i p i s probably l i n e a r , though there i s a g e n e r a l trend towards negative r e s i d u a l s at i n t e r m e d i a t e biomass. S t r a t i f i c a t i o n ( F i g . 45b) c o u l d be a s e l e c t i n g f a c t o r , though at i n t e r m e d i a t e v a l u e s (Aat = 2-3) a wide range of biomass r e s u l t s . Perhaps these organisms have a s i m i l a r e c o l o g i c a l s t r a t e g y as the p h o t o s y n t h e t i c d i n o f l a g e l l a t e s . A l s o , as f o r d i n o f l a g e l l a t e s , these organisms i n c r e a s e with d e c r e a s i n g n i t r a t e c o n c e n t r a t i o n ( F i g . 45c) which shows no c o l l i n e a r i t y with s t r a t i f i c a t i o n 195 (-0.18). Mesodinum rubrum, the only s p e c i e s i n the group p h o t o s y n t h e t i c c i l i a t e s , has a s i g n i f i c a n t r e g r e s s i o n equation which i s : Ln(biomass) = 0.987 - 0.0839xs - 0.125xp - 0.439xt - 0.230xn - 0.0658xg (13.9) (-0.742) (-1.43) (-3.37) (-2.35) (-0.793) F = 5.68 df = 5,65 R 2 = 0.304 S i g n i f i c a n t c o e f f i c i e n t s are s u r f a c e temperature (p < 0.025), n i t r a t e (p < 0.025), and p y c n o c l i n e depth (p < 0.10). The r e l a t i o n s h i p i s l i n e a r ( F i g . 46a) and the v a r i a n c e of the random component has remained f a i r l y constant (homoscedastic). T h i s c i l i a t e shows a c l e a r decrease with s u r f a c e temperature ( F i g . 46b), with a few l a r g e r e s i d u a l s at higher biomass. T h i s t r e n d i s c o n s i s t e n t with the o b s e r v a t i o n s of Lindholm (1985), Fonds and Eisma (1967), and others who have found Mesodinium i n areas of upwelling, where c o o l e r , n u t r i e n t - r i c h water i s brought to the s u r f a c e . Contrary to t h i s view i s F i g . 46c i n which Mesodinium appears to be more abundant i n areas of lower n i t r a t e . One must keep in mind, however, that the n i t r a t e value i s an average of the four depths per s t a t i o n , and not s u r f a c e n i t r a t e per se. The p l o t of biomass a g a i n s t n i t r a t e shows much s c a t t e r and c o u l d probably be made to show a reverse t r e n d i f the data with the l a r g e r r e s i d u a l s were removed. H e t e r o t r o p h i c c i l i a t e s are s i g n i f i c a n t l y d e s c r i b e d by the r e g r e s s i o n equation: Ln(biomass) = 2.92 + 0.276xs + 0.0544xp + 0.00571xt + 0.0724xn + 0.!26xg 196 (50.8) (3.13) (0.768) (0.0547) (0.906) (1.77) F = 5.21 df = 5,65 R 2 = 0.286 S i g n i f i c a n t c o e f f i c i e n t s are given f o r s t r a t i f i c a t i o n (p < 0.025) and g r a z i n g (p < 0.05). The equation i s d e s c r i b i n g a l i n e a r r e l a t i o n s h i p ( F i g . 47a). The t r e n d towards g r e a t e r biomass with i n c r e a s i n g s t r a t i f i c a t i o n ( F i g . 47b) i s c o n v i n c i n g though much s c a t t e r e x i s t s . I t i s c u r i o u s that h e t e r o t r o p h i c organisms show an a f f i n i t y f o r s t r a t i f i c a t i o n . One e x p l a n a t i o n c o u l d be that at higher s t r a t i f i c a t i o n s , diatoms were probably abundant i n the l e s s s t r a t i f i e d areas, e x c l u d i n g the n a n o f l a g e l l a t e s from these a r e a s . T h e r e f o r e , the c i l i a t e s would be more abundant i n the s t r a t i f i e d areas where the n a n o f l a g e l l a t e s are now growing. The n a n o f l a g e l l a t e r e g r e s s i o n , however, i n d i c a t e s that these organisms are l e s s abundant i n s t r a t i f i e d a r e a s . Perhaps n a n o f l a g e l l a t e s appear to be l e s s abundant in s t r a t i f i e d areas but are i n f a c t more p r o d u c t i v e here. Close c o u p l i n g of microheterotrophs to prey due to short g e n e r a t i o n times of the c i l i a t e s (Beers & Stewart, 1970; Hannah & Boney, 1983) c o u l d mean a constant g r a z i n g p r e s s u r e that c o u l d dampen any i n c r e a s e i n n a n o f l a g e l l a t e biomass. 1 97 F i g u r e 33. Organismal r e g r e s s i o n c o e f f i c i e n t s . Each ray of a s t a r p l o t corresponds to one of the independent v a r i a b l e s : 0° = S t r a t i f i c a t i o n (Aot) 72° = P y c n o c l i n e depth (m) 144° = Surface temperature (°C) 216° = N i t r a t e (/uM) 288° = G r a z i n g (phaeopigments/chlorophyll a ) V a r i a b l e s ' r e g r e s s i o n c o e f f i c i e n t s appear at t e r m i n i of r e s p e c t i v e rays. Length of each ray w i t h i n a s t a r p l o t i s p r o p o r t i o n a l to each r e g r e s s i o n c o e f f i c i e n t ' s t - v a l u e . Note t h a t l e n g t h i s not r e l a t i v e amongst s t a r p l o t s . F i g u r e 34. Diatom r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d (standardised) r e s i d u a l s of diatom r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d values f o r diatom biomass. Biomass values with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l diatom biomass p l o t t e d a g a i n s t g r a z i n g (t=-5.54). S i z e of c i r c l e s i n b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l diatom biomass p l o t t e d a g a i n s t s u r f a c e temperature (t=3.53). F i g u r e 35. Diatom r e g r e s s i o n c o e f f i c i e n t s . Each ray of a s t a r p l o t corresponds to one of the independent v a r i a b l e s : 0° = S t r a t i f i c a t i o n (Act) 72° = P y c n o c l i n e depth (m) 144° = Surface temperature (°C) 216° = N i t r a t e (/uM) 288° = G r a z i n g (phaeopigments/chlorophyll a ) V a r i a b l e s ' r e g r e s s i o n c o e f f i c i e n t s appear at t e r m i n i of r e s p e c t i v e r a y s . Length of each ray w i t h i n a s t a r p l o t i s p r o p o r t i o n a l to each r e g r e s s i o n c o e f f i c i e n t ' s t - v a l u e . Note that l e n g t h i s not r e l a t i v e amongst s t a r p l o t s . 198 F i g u r e 33 . O r g a n i s m a l R e g r e s s i o n C o e f f i c i e n t s F i g u r e 34 . D ia toms 200 201 F i g u r e 36. Lower biomass diatom r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d (standardised) r e s i d u a l s of lower biomass diatom r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d v alues f o r lower biomass diatom biomass. Biomass val u e s with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l lower biomass diatom biomass p l o t t e d a g a i n s t s u r f a c e temperature (t=-2.15). S i z e of c i r c l e s i n b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l lower biomass diatom biomass p l o t t e d a g a i n s t s t r a t i f i c a t i o n (t=-1.97). F i g u r e 37. Higher biomass diatom r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d (standardised) r e s i d u a l s of higher biomass diatom r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d values f o r higher biomass diatom biomass. Biomass val u e s with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l higher biomass diatom biomass p l o t t e d a g a i n s t s u r f a c e temperature (t=2.02). S i z e of c i r c l e s i n b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l higher biomass diatom biomass p l o t t e d a g a i n s t p y c n o c l i n e depth (t=-0.894). F i g u r e 38. P h o t o s y n t h e t i c d i n o f l a g e l l a t e r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d ( s t a n d a r d i s e d ) r e s i d u a l s of p h o t o s y n t h e t i c d i n o f l a g e l l a t e r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d values f o r p h o t o s y n t h e t i c d i n o f l a g e l l a t e biomass. Biomass values with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l p h o t o s y n t h e t i c d i n o f l a g e l l a t e biomass p l o t t e d a g a i n s t s t r a t i f i c a t i o n (t=3.92). S i z e of c i r c l e s i n b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l p h o t o s y n t h e t i c d i n o f l a g e l l a t e biomass p l o t t e d a g a i n s t n i t r a t e (t=-3.85). 202 F i g u r e 36. Lower Biomass Diatoms .8 10 12 S u r f a c e Tempera tu re (°C) o o o o oo <9 O 1 2 3 4 S t r a t i f i c a t i o n (Del ta-D) 5 203 F i g u r e 37. Higher Biomass Diatoms A A a - A * A A * -A S * A - A A A A A A A i i i .5 4 .0 4 .5 5.0 5.5 6. F i t t e d V a l u e s (Ln ng C-mr1) - o o Hj> °« b • O . o n • • O - o o o o o • • . i i 1 1 10 12 14 16 S u r f a c e Tempera tu re (°C) IB 20 22 10 15 20 P y c n o c l i n e Depth (m) 204 F i g u r e 38. P h o t o s y n t h e t i c D i n o f l a g e l l a t e s n | 1 1 a Nitrate (uM) cvi 205 F i g u r e 39. H e t e r o t r o p h i c d i n o f l a g e l l a t e r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d (standardised) r e s i d u a l s of h e t e r o t r o p h i c d i n o f l a g e l l a t e r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d values f o r h e t e r o t r o p h i c d i n o f l a g e l l a t e biomass. Biomass values with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l h e t e r o t r o p h i c d i n o f l a g e l l a t e biomass p l o t t e d a g a i n s t s t r a t i f i c a t i o n (t=1.64). S i z e of c i r c l e s in b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l h e t e r o t r o p h i c d i n o f l a g e l l a t e biomass p l o t t e d a g a i n s t p y c n o c l i n e depth (t=-1.28). F i g u r e 40. H e t e r o t r o p h i c d i n o f l a g e l l a t e r e g r e s s i o n c o e f f i c i e n t s . Each ray of a s t a r p l o t corresponds to one of the independent v a r i a b l e s : 0° = S t r a t i f i c a t i o n (Aat) 72° = P y c n o c l i n e depth (m) 144° = Surface temperature (°C) 216° = N i t r a t e U M ) 288° = Grazing (phaeopigments/chlorophyll a ) V a r i a b l e s ' r e g r e s s i o n c o e f f i c i e n t s appear at t e r m i n i of r e s p e c t i v e r a y s . Length of each ray w i t h i n a s t a r p l o t i s p r o p o r t i o n a l to each r e g r e s s i o n c o e f f i c i e n t ' s t - v a l u e . Note that l e n g t h i s not r e l a t i v e amongst s t a r p l o t s . F i g u r e 41. Gyrodinium r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d (standardised) r e s i d u a l s of Gyrodinium r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d values f o r Gyrodinium biomass. Biomass valu e s with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s Were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l Gyrodinium biomass p l o t t e d a g a i n s t s t r a t i f i c a t i o n (t=3.23). S i z e of c i r c l e s i n b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l Gyrodinium biomass p l o t t e d a g a i n s t (t=1.86). 206 F i g u r e 39. H e t e r o t r o p h i c D i n o f l a g e l l a t e s CO cu h 0 3 T J O w4 n o t r * i cu 207 F i g u r e 40. H e t e r o t r o p h i c D i n o f l a g e l l a t e Regression C o e f f i c i e n t s n o c o c o Jp 0 X 17 R2 - 0.24 F i g u r e 41. Gyrodinium 208 1.0 1.5 2.0 2.5 3.0 3.5 Fitted Values (Ln ng C-ml" 1 ) b j i 1 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 Stratification (Delta-D) i i i 1 1 1 0 5 10 15 20 25 Nitrate (uM) 209 F i g u r e 42. P r o t o p e r i d i n i u m r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d (standardised) r e s i d u a l s of P r o t o p e r i d i n i u m r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d values f o r P r o t o p e r i d i n i u m biomass. Biomass valu e s with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l P r o t o p e r i d i n i u m biomass p l o t t e d a g a i n s t s u r f a c e temperature (t=7.25). S i z e of c i r c l e s i n b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l P r o t o p e r i d i n i u m biomass p l o t t e d a g a i n s t g r a z i n g (t=-4.21). F i g u r e 43. P h o t o s y n t h e t i c n a n o f l a g e l l a t e r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d (standardised) r e s i d u a l s of p h o t o s y n t h e t i c n a n o f l a g e l l a t e r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d v a l u e s f o r p h o t o s y n t h e t i c n a n o f l a g e l l a t e biomass. Biomass valu e s with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l p h o t o s y n t h e t i c n a n o f l a g e l l a t e biomass p l o t t e d a g a i n s t s u r f a c e temperature (t=2.76). S i z e of c i r c l e s i n b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l p h o t o s y n t h e t i c n a n o f l a g e l l a t e biomass p l o t t e d a g a i n s t s t r a t i f i c a t i o n ( t = - 2 . l 5 ) . F i g u r e 44. H e t e r o t r o p h i c n a n o f l a g e l l a t e r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d (standardised) r e s i d u a l s of h e t e r o t r o p h i c n a n o f l a g e l l a t e r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d v a l u e s f o r h e t e r o t r o p h i c n a n o f l a g e l l a t e biomass. Biomass valu e s with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l h e t e r o t r o p h i c n a n o f l a g e l l a t e biomass p l o t t e d a g a i n s t s u r f a c e temperature (t=3.85). S i z e of c i r c l e s i n b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l h e t e r o t r o p h i c n a n o f l a g e l l a t e biomass p l o t t e d a g a i n s t s t r a t i f i c a t i o n (t=-1.73). F i g u r e 42. P r o t o p e r i d i n i u m F i g u r e 43. P h o t o s y n t h e t i c N a n o f l a g e l l a t e s 4.0 0 1 2 3 4 5 Stratification (Dslta-O) F i g u r e 44. H e t e r o t r o p h i c N a n o f l a g e l l a t e s 12 14 16 Surface Temperature (°C) 1.0 E *« 6 CB 3 m »° n a S<r «-i • m o 5 o O tP O •o r »0 • O O • c> O -O (9 _i_ 3 4 3 S t r a t i f i c a t i o n (Delta-D) 6 213 F i g u r e 45. P h o t o s y n t h e t i c f l a g e l l a t e r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d (standardised) r e s i d u a l s of p h o t o s y n t h e t i c f l a g e l l a t e r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d v a l u e s f o r p h o t o s y n t h e t i c f l a g e l l a t e biomass. Biomass values with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l p h o t o s y n t h e t i c f l a g e l l a t e biomass p l o t t e d a g a i n s t s t r a t i f i c a t i o n (t=3.62). S i z e of c i r c l e s i n b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l p h o t o s y n t h e t i c f l a g e l l a t e biomass p l o t t e d a g a i n s t n i t r a t e (t=-2.33). F i g u r e 46. Mesodinium rubrum r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d Tstandardised) r e s i d u a l s of Mesodinium rubrum r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d values f o r Mesodinium rubrum biomass. Biomass values with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l Mesodinium rubrum biomass p l o t t e d a g a i n s t s u r f a c e temperature (t=-3.37). S i z e of c i r c l e s i n b and c i s p r o p o r t i o n a l t o magnitude of r e s i d u a l s . c. O r i g i n a l Mesodinium rubrum biomass p l o t t e d a g a i n s t n i t r a t e (t=-2.35). F i g u r e 47. H e t e r o t r o p h i c c i l i a t e r e g r e s s i o n a n a l y s i s . a. S t u d e n t i z e d (standardised) r e s i d u a l s of h e t e r o t r o p h i c c i l i a t e r e g r e s s i o n p l o t t e d a g a i n s t the f i t t e d v alues f o r h e t e r o t r o p h i c c i l i a t e biomass. Biomass v a l u e s with o r i g i n a l r e s i d u a l s o u t s i d e ± 1.96 standard d e v i a t i o n s were removed and the r e g r e s s i o n was performed on the reduced data s e t . b. O r i g i n a l h e t e r o t r o p h i c c i l i a t e biomass p l o t t e d a g a i n s t s t r a t i f i c a t i o n (t=3.13). S i z e of c i r c l e s in b and c i s p r o p o r t i o n a l to magnitude of r e s i d u a l s . c. O r i g i n a l h e t e r o t r o p h i c c i l i a t e biomass p l o t t e d a g a i n s t g r a z i n g (t=1.77). F i g u r e 4 5 . P h o t o s y n t h e t i c F l a g e l l a t e s 215 F i g u r e 46. Mesodinium rubrum A » A A A AA A A A A A A A At A „ A A A A A A T - — * — * A A A A A A A A A , A A A I Q.O 0.5 1.0 , i - S 2 - ° F i t t e d V a l u e s (Ln ng C-ml'1) _i i t-B 10 12 14 16 IB 20 S u r f a c e Tempera tu re (°C) E 6 n to a e o O o GP o 4 ^ o $<io6<>0-V o o # 5 10 15 20 23 N i t r a t e (uH) F i g u r e 47 . H e t e r o t r o p h i c C i l i a t e s ro cu 216 a 3 TJ O to O I cu I rn I • i i i i t I 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 Fitted Values (Ln ng C-ml"1) 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 Grazing (phaeo/chloro) 217 4. DISCUSSION The northern S t r a i t of Georgia proved to be a dynamic e c o l o g i c a l regime. Even though s p e c i e s abundance and d i v e r s i t y i n c r e a s e d as the seasons progressed, there seems to be a background h e t e r o g e n e i t y which perhaps p e r s i s t s year round. There have been no comparable s t u d i e s i n t h i s area so that i t i s hard to know whether 1986 was a t y p i c a l year. Consequently, with the e x c e p t i o n of major oceanographic f e a t u r e s , such as the t i d a l j e t through D i s c o v e r y Passage and s a l i n i t y s t r a t i f i c a t i o n i n the southeast, any d i s c u s s i o n f o l l o w i n g i s l i m i t e d t o t h i s year and g e n e r a l i t i e s r e g a r d i n g the system's b i o l o g i c a l c h a r a c t e r can only await f u t u r e c o n f i r m a t i o n . 4_._1_ Absence of a S p r i n g Bloom The b i g g e s t s u r p r i s e a r i s i n g from the f i r s t three c r u i s e s was the absence of a s p r i n g diatom bloom. C h l o r o p h y l l was c e r t a i n l y low and n i t r a t e high i n both March and A p r i l , and by June the S t r a i t was dominated by p h o t o s y n t h e t i c f l a g e l l a t e s . Nowhere d u r i n g t h i s p e r i o d was there evidence of e l e v a t e d diatom abundance. I t i s p o s s i b l e that the s p r i n g bloom was missed between A p r i l and June. I t seems that although the important s p r i n g diatoms (Skeletonema and T h a l a s s i o s i r a ) were present, they d i d not have the o p p o r t u n i t y to bloom. In c o n t r a s t to the s i t u a t i o n i n the NSG, diatom biomass i n the MC was very high i n both March and A p r i l . U s u a l l y a s p r i n g bloom can begin when diatoms are s u b j e c t e d to good l i g h t 218 c o n d i t i o n s , and t h i s happens when the depth of mixing becomes l e s s than the c r i t i c a l depth (Sverdrup, 1953). Although s t r a t i f i c a t i o n v alues were g e n e r a l l y low and s i m i l a r between the two areas i n s p r i n g , the d e n s i t y d i f f e r e n c e i n the MC was gr e a t e r on average and was p i c k e d out as a s i g n i f i c a n t f a c t o r a f f e c t i n g the s p e c i e s composition along PCI i n both March's and A p r i l ' s c a n o n i c a l a n a l y s e s . In March, t h i s low s t r a t i f i c a t i o n i n the MC was due mostly to temperature, which may have been suppressed i n the NSG by f a r gr e a t e r exposure to winter winds and a l a r g e r f e t c h over which to b u i l d wind momentum. The MC l i e s i n a NW-SE d i r e c t i o n with i t s mouth opening i n the NW. The r e f o r e , winter s o u t h e a s t e r l i e s , blowing from mid-September to m i d - A p r i l ( T u l l y and Dodimead, 1957) have l e s s e f f e c t on t h i s system, the i n l e t s being p r o t e c t e d by Malaspina P e n i n s u l a to the south. In A p r i l , the d i f f e r e n c e between the two was a t t r i b u t e d more to a s l i g h t s a l i n i t y s t r a t i f i c a t i o n . Freshwater r u n o f f would have a g r e a t e r e f f e c t i n a smaller and f a i r l y e n c l o s e d body of water. P a r t s of the NSG (the east s i d e ) were as e q u a l l y s t r a t i f i e d as the MC d u r i n g t h i s p e r i o d but the s p e c i e s composition was q u i t e d i f f e r e n t between the two areas. One must wonder whether s t r a t i f i c a t i o n was the r e a l determining f a c t o r i n the r e g i o n a l d i f f e r e n c e s at t h i s time. C l a s s i c a l l y , the depth of mixing has been taken to be l i m i t e d by the p y c n o c l i n e , but when s t r a t i f i c a t i o n i s minimal the depth of mixing can be c o n s i d e r e d to be p r i m a r i l y a product of wind s t r e s s ( v e l o c i t y , d u r a t i o n , 219 and f e t c h ) . The i n l e t s were a l o t calmer, d u r i n g sampling, than the open S t r a i t . I n t u i t i v e l y , at t h i s time of year s t r a t i f i c a t i o n cannot be too great a f a c t o r compared to wind-induced t u r b u l e n c e . Hannah and Boney (1983) noted f o r the F i r t h of Clyde that i f winds are prolonged i n s p r i n g , the s p r i n g bloom can be delayed f o r months and even occurs without the dominance of Skeletonema and T h a l a s s i o s i r a . In winter, e x p r e s s i o n of the p o t e n t i a l p r o d u c t i o n r a t e depends on wind-induced turb u l e n c e (Cushing, 1962). Thus, i n p r o t e c t e d Indian Arm, G i l m a r t i n (1964) observed a p r o d u c t i o n i n c r e a s e before any r e a l i n c r e a s e i n seasonal i r r a d i a n c e . I t would appear that the MC experienced a s i m i l a r f a c i l i t a t i o n r e s u l t i n g i n a c l o s e r c o u p l i n g of the a c t u a l p r o d u c t i o n r a t e to the p o t e n t i a l p r o d u c t i o n r a t e than was p o s s i b l e i n the NSG. Another f a c t o r to c o n s i d e r i n s p r i n g i s the suppression of biomass by g r a z i n g . Ryther and Sanders (1980) found that s e l e c t i v e g r a z i n g by A c a r t i a tonsa on Skeletonema costatum s h i f t e d the s i z e d i s t r i b u t i o n of phytoplankton assemblages. Smaller s i z e c l a s s e s , c h i e f l y composed of m i c r o f l a g e l l a t e s , became dominant. If environmental c o n d i t i o n s are such that diatoms are not growing at t h e i r maximal r a t e s , g r a z i n g pressure may be great enough to prevent diatoms a c h i e v i n g h i g h biomass. In the North P a c i f i c , zooplankton l i f e s t r a t e g i e s are such that deep o v e r w i n t e r i n g p o p u l a t i o n s of a d u l t copepods l a y t h e i r eggs i n s p r i n g which hatch c o i n c i d e n t with the i n c r e a s e in diatom biomass (Parsons & LeBrasseur, 1968). N a u p l i a r g r a z i n g e f f e c t i v e l y damps out any s i g n of standing stock i n c r e a s e even 220 though primary p r o d u c t i v i t y may be h i g h . In the S t r a i t of Georgia, F u l t o n (1973) d e s c r i b e d the l i f e c y c l e of Neocalanus plumchrus. T h i s copepod spends 265 days of the year i n deeper waters where p r e d a t i o n w i l l be minimal. Eggs are l a i d i n water deeper than 300 m and upon h a t c h i n g , the n a u p l i a r stage comes to the s u r f a c e i n time f o r the s p r i n g bloom. If the bloom were delayed by e x c e s s i v e wind t u r b u l e n c e , the w a i t i n g p o p u l a t i o n of n a u p l i i would present a l a r g e g r a z i n g pressure which c o u l d c o n c e i v a b l y prevent the bloom from o c c u r r i n g when c o n d i t i o n s do become favourable f o r r a p i d growth. During the March and A p r i l sampling, i t appeared that a l a r g e g r a z i n g pressure a l r e a d y e x i s t e d due to microzooplankton. C i l i a t e s such as Strombidium and t i n t i n n i d s , as w e l l as the h e t e r o t r o p h i c d i n o f l a g e l l a t e Gyrodinium s p i r a l e , comprised the dominant biomass of organisms s t u d i e d , exceeding the autotrophs i n March. I n d i r e c t evidence presented suggests that these m i c r o z o o p l a n k t e r s were g r a z i n g the n a n o f l a g e l l a t e s and would probably u t i l i s e any small diatoms pre s e n t . Smetacek (1981) found that the i n i t i a l s p r i n g peak of (mostly n o n - l o r i c a t e ) c i l i a t e biomass in the K i e l Bight d u r i n g 1973 c o i n c i d e d with a n a n o f l a g e l l a t e peak. Using a u t o c o r r e l a t i o n , Ibanez and Rassoulzadegan (1977) suggested that l a r g e r c i l i a t e s (>30 nm) predated n a n o f l a g e l l a t e s while s m a l l e r c i l i a t e s u t i l i s e d the u l t r a p l a n k t o n a s s o c i a t e d with nanoplankton p o p u l a t i o n d e c l i n e s . Using c o r r e l a t i o n a n a l y s i s , B u r k h i l l (1982) found a very s i g n i f i c a n t a s s o c i a t i o n between naked c i l i a t e s and nanophytoplankton. There was a l s o a l e s s s i g n i f i c a n t c o r r e l a t i o n 221 between t i n t i n n i d s and nanophytoplankton. The d i f f e r e n c e i n s i g n i f i c a n c e he a t t r i b u t e d to a p o s s i b l e q u i c k e r predator response time by the naked c i l i a t e s which c o u l d have higher growth r a t e s (comparable to phytoplankton). Takahashi and Hoskins (1978) r e p o r t e d that i n Saanich I n l e t n a n o f l a g e l l a t e s dominate i n winter, p u l s e s of which were f o l l o w e d by i n c r e a s e s i n microzooplankton biomass. M i c r o s c o p i c a l o b s e r v a t i o n s by Smetacek (1981) found Strombidium s p e c i e s with ingested diatoms, some of which were q u i t e l a r g e . The n o n - l o r i c a t e c i l i a t e s are a p p a r e n t l y more o p p o r t u n i s t i c , being capable of i n g e s t i n g a l a r g e s i z e range of food s p e c i e s so t h a t , p o t e n t i a l l y , they may be competitors with macrozooplankton. L o r i c a t e forms such as t i n t i n n i d s are r e s t r i c t e d to food s p e c i e s which can pass through t h e i r l o r i c a openings and are c o n s i d e r e d g r a z e r s on nanoplankton (Heinbokel, 1978; Heinbokel & Beers, 1979). T h e r e f o r e , g r a z i n g competition may be a common f e a t u r e of the NSG i n s p r i n g , with microzooplankton success being one reason why N. plumchrus was found to be l e s s abundant at the more n o r t h e r l y s t a t i o n s (to southern Texada Island) i n Black's (1984) study. Parsons et a l . (1970) a l s o r e p o r t e d that the zooplankton biomass i n the NSG d u r i n g March 22-23, 1966, was low compared to the southern S t r a i t . I n t e r e s t i n g l y , g r a z i n g pressure i n the MC seemed to be l e s s of a f a c t o r as heterotrophs here comprised a lower percentage of the t o t a l biomass than found i n the S t r a i t . Due to i t s f a i r l y shallow depth (maximum = 80 m), one would not expect s u b s t a n t i a l 222 n a u p l i a r g r a z i n g . The MC t h e r e f o r e appears to not only experience l e s s wind s t r e s s but a l s o a lower degree of g r a z i n g , both of which would be conducive to diatom growth. Another i n t e r e s t i n g f e a t u r e of t h i s complex i s the apparent s t i m u l a t o r y e f f e c t t i d a l a c t i v i t y has on the pr o d u c t i o n at the j u n c t i o n of the three i n l e t s . Malaspina I n l e t i t s e l f i s narrow and shallow so that t i d a l streaming tends to mix waters i n t h i s i n l e t to homogeneity. Upon a f l o o d t i d e , the waters at the j u n c t i o n would r e c e i v e an input of n u t r i e n t - r i c h water as w e l l as a degree of t i d a l s t i r r i n g which i s not so severe that p r o d u c t i o n i s i n h i b i t e d , but r a t h e r appears to s t i m u l a t e diatom growth. A s i m i l a r t i d a l s i t u a t i o n occurs i n the Rupert-Holberg I n l e t system on northern Vancouver I s l a n d ( S t u c c h i , 1980) which e x h i b i t s r i c h s p r i n g diatom blooms (F.J.R. T a y l o r , p e r s . comm.). 4.2 Advanced E c o l o g i c a l S t a b i l i t y By June both areas had advanced to Margalef's (1958) Stage III of s u c c e s s i o n where the system i s dominated by n a n o f l a g e l l a t e s and d i n o f l a g e l l a t e s . I n t e r e s t i n g l y , both systems shared many of the upper s t r a t i f i e d water organisms as d e s c r i b e d by the c a n o n i c a l c o r r e l a t i o n a n a l y s e s . I t was found, however, that s p e c i e s a f f i n i t y f o r s p e c i f i c depths was more pronounced i n the NSG as though t h i s area was now e x p e r i e n c i n g a l e s s e r degree of t u r b u l e n c e than i n the MC. There was no evidence that a diatom bloom had occurred s i n c e A p r i l . In f a c t , the diatoms were at t h e i r lowest l e v e l . Even more s u r p r i s i n g l y , they were not t a k i n g advantage of the 223 t i d a l j e t ' s t u r b u l e n c e . T h i s t i d a l e f f e c t c l e a r l y upset s t r a t i f i c a t i o n , reducing i t from an ambient Aat of 3-4 to 2. Nearly every other organism s t u d i e d responded to the d i s t u r b a n c e . N i t r a t e was low i n s u r f a c e waters throughout the NSG i n June but was not e s p e c i a l l y d e p l e t e d 3-5 uM N 0 3 ) . N i t r a t e l i m i t a t i o n should not be a problem f o r most s p e c i e s at t h i s time. Parsons et a l . (1981) noted that the D i s c o v e r y Passage t i d a l j e t can introduce n u t r i e n t s d i r e c t l y . There c o u l d a l s o be a c e r t a i n amount of entrainment from deeper l a y e r s . Because s t r a t i f i c a t i o n was not completely upset, one would expect that l i g h t would be conducive f o r growth, e s p e c i a l l y given the a v a i l a b i l i t y of "new n i t r o g e n " ( N 0 3 ) . N a n o f l a g e l l a t e s were again found most abundant i n areas of t i d a l mixing i n the north. C i l i a t e abundance was a l s o very high in t h i s region and was almost t r i p l e the biomass of both the p h o t o s y n t h e t i c and non-photosynthetic n a n o f l a g e l l a t e s . Consequently, one must assume that n a n o f l a g e l l a t e p r o d u c t i v i t y was very high here, otherwise such e x c e s s i v e c i l i a t e biomass c o u l d not be maintained. There are many s t u d i e s which have h i g h l i g h t e d the importance of nanoplankton p r o d u c t i v i t y to t o t a l p r o d u c t i v i t y (e.g., Rodhe et a_l. , 1958; G i l m a r t i n , 1964; Malone, 1971a; Malone, 1971b; Mommaerts, 1973; McCarthy et a l . , 1974; Gieskes & Kraay, 1975; and S k j o l d a l & Lannergren, 1978); however, as S k j o l d a l and Lannergren (1978) p o i n t e d out, small diatoms can sometimes c o n t r i b u t e the m a j o r i t y of the biomass to nanoplankton. A l l these s t u d i e s made use of v a r y i n g mesh s i z e 224 nets (20-90 Aim) to separate nanoplankton and netplankton, so that c o n c l u s i o n s are not as e c o l o g i c a l l y meaningful as those reached by authors who a c t u a l l y looked at the organisms ( H a l l e g r a e f f , 1981; Hannah & Boney, 1983). June's p h o t o s y n t h e t i c dominant was Heterosigma akashiwo which was abundant throughout the northern S t r a i t at a l l depths sampled. I t s p a t t e r n suggested that i t was responding to the n u t r i e n t pump e f f e c t of the plume. Tomas (1978, as O l i s t h o d i s c u s  l u t e u s ) found that i t e x h i b i t e d maximal growth r a t e s (>1 d i v ' d a y - 1 ) between s a l i n i t i e s of 15 and 30 ppt at 10° and 15°C, c o n d i t i o n s present i n the S t r a i t at t h i s time. Furthermore, Tomas (1980) suggested t h a t , i n Narragansett Bay where a y e a r l y bimodal p a t t e r n occurs, temperature i s one of the more important f a c t o r s . He found that the abundance peaks co-occurred q u i t e s t r i k i n g l y with minimal d e v i a t i o n s away from 15°C, the f l a g e l l a t e ' s optimal temperature. Surface waters of the S t r a i t were 15°C at t h i s time. P r a t t (1966) hypothesised that the a l t e r n a t i n g dominance of H. akashiwo (as 0. l u t e u s ) and S. costatum i n Narragansett Bay, might be due i n p a r t to chemical c o m p e t i t i o n (or more a c c u r a t e l y , i n h i b i t i o n ) . I t was thought by P r a t t (1966) that H. akashiwo r e l e a s e s some form of t a n i n which may cause c e l l l y s i s of other phytoplankton; however, Cleve and Stewart ( c i t e d i n Tomas, 1980) found that t h i s i n h i b i t i o n was temporary. The nature of any t o x i c e f f e c t of Heterosigma i s s t i l l not d e f i n i t i v e but i t i s i n t r i g u i n g to note that the minimal diatom abundance i n the S t r a i t o c c u r r e d at a time when t h i s f l a g e l l a t e 2 2 5 was u b i q u i t o u s and k i l l s of caged salmon have been a s s o c i a t e d with blooms of i t . There i s no obvious other reason why diatom biomass was so low everywhere, e s p e c i a l l y s i n c e there were l o c a t i o n s where diatoms would be expected to t h r i v e , such as the plume of the t i d a l j e t . In Malaspina I n l e t , c i l i a t e s were s t i l l an important f o r c e . W i t hin the other two i n l e t s , Mesodinium rubrum became an overwhelming biomass dominant, p a r t i c u l a r l y i n Okeover I n l e t . T h i s p h o t o s y n t h e t i c c i l i a t e was shown by the m u l t i p l e r e g r e s s i o n a n a l y s i s to be h i g h l y c o r r e l a t e d with low s u r f a c e temperatures, an i n d i c a t o r of mixing. The only n o t i c e a b l e f e a t u r e of Okeover i s the very obvious n i t r a t e d e p l e t i o n . Although Mesodinium i s probably l a r g e l y r e s p o n s i b l e f o r such a c o n d i t i o n , i t may be ab l e to e x p l o i t t h i s environment b e t t e r than other s p e c i e s due to i t s powers of locomotion and v e r t i c a l m i g r a t i o n (Lindholm, 1 9 8 5 ) . Thus, we would have an example of an organism changing i t s environment to i t s own advantage. 4_.3_ B i o l o g i c a l Mosaicism By August, s u r f a c e waters were the most n u t r i e n t - d e p l e t e d of a l l the sampling p e r i o d s . T h i s was very n o t i c e a b l e on the east s i d e and i n the south ( N 0 3 <1 MM i n top 10 m), whereas northern waters remained e s s e n t i a l l y n u t r i e n t s u f f i c i e n t , presumably due to the t i d a l mixing i n t h i s a r e a . Between the June and August samplings, a diatom bloom c o n s i s t i n g c h i e f l y of Chaetoceros spp. may have occ u r r e d s i n c e they were the dominants i n the August samples, mostly at 1 0 - 1 5 m. T h e i r congregation i n 226 the north and west suggests that they may have found a niche o f f e r i n g both s u f f i c i e n t l i g h t i r r a d i a n c e s and a constant n u t r i e n t f l u x by t i d a l streaming, e n t r a i n i n g n u t r i e n t s from below the p y c n o c l i n e (Pingree et a l . , 1976), but they may have been i n the process of s i n k i n g out of shallower depths as n i t r a t e d e p l e t i o n set i n . Buchanan (1966) suggested that p a s s i v e p l a n k t e r s i n Indian Arm were maintained above the p y c n o c l i n e due to the entrainment of water from below. There was a l s o an i s o l a t e d patch of higher diatom biomass l o c a t e d between Savary I s l a n d and Malaspina Peninsula which was probably a r e s u l t of i n c r e a s i n g mixing through the narrow passage or about an i s l a n d mass. Simpson et a l . (1982) found that mixing about the S c i l l y I s l e s ( C e l t i c Sea) was e f f e c t i v e i n s t i m u l a t i n g phytoplankton growth at depth due to i n j e c t i o n of mixed water along the p y c n o c l i n e . The n a n o f l a g e l l a t e s and d i n o f l a g e l l a t e s were no longer most abundant i n areas of higher t i d a l t urbulence but p r e f e r r e d the very n u t r i e n t - d e p l e t e d southeast of the S t r a i t . U s u a l l y n a n o f l a g e l l a t e s have lower h a l f - s a t u r a t i o n constants (Ks) f o r n u t r i e n t uptake (Eppley et a l . , 1969) i n d i c a t i n g that these organisms are b e t t e r a b l e to s u r v i v e i n a low n u t r i e n t environment. D i n o f l a g e l l a t e s can have very high Ks v a l u e s (Eppley et a l . , 1969) and slow growth r a t e s , but as long as the n u t r i c l i n e i s no deeper than 10-20 m, these f l a g e l l a t e s should be able to v e r t i c a l l y migrate downward to take up n u t r i e n t s (Eppley et a l . , 1968; H a r r i s o n , 1976). H e t e r o t r o p h i c n a n o f l a g e l l a t e s , c o n s i s t i n g mostly of 227 c h o a n o f l a g e l l a t e s , have not been d i s c u s s e d here so f a r . I t has been re c o g n i s e d f o r some time that these s m a l l grazers are an important l i n k i n the food web, g r a z i n g b a c t e r i a and p r o v i d i n g food f o r c i l i a t e s ( S orokin, 1 977; Fenchel, 1982; Davis e_t a l . , 1985; Caron et a l . , 1986). Fenchel (1982) estimated t h a t on average, 20% of the water i n L i m f j o r d , Denmark, i s f i l t e r e d by these heterotrophs per day. A l s o , some of the h e t e r o t r o p h i c n a n o f l a g e l l a t e s can be her b i v o r o u s , g r a z i n g on diatoms t h e i r own s i z e (Caron et al . . , 1985; Goldman & Caron, 1985). In August, these organisms were conc e n t r a t e d mainly i n the northeast near the diatom biomass. Conceivably, they c o u l d be g r a z i n g s m a l l e r diatoms a s s o c i a t e d with the l a r g e Chaetoceros spp.; however, i t i s expected that b a c t e r i a l biomass i n c r e a s e d with the diatom bloom due to e x c r e t i o n of organic compounds by diatoms ( B e l l et a l . , 1974; B e l l , 1980, L i n l e y et a l . , 1983) so that these n a n o f l a g e l l a t e s were most l i k e l y g r a z i n g b a c t e r i a . T h i s area was a l s o the most a c t i v e s i t e f o r h e t e r o t r o p h i c d i n o f l a g e l l a t e g r a z i n g on diatoms, an a c t i v i t y that might a l s o s t i m u l a t e b a c t e r i a l biomass v i a r e l e a s e of o r g a n i c s . O v e r a l l , the northern S t r a i t i n August showed g r e a t e r s p e c i e s d i f f e r e n t i a t i o n along the east-west a x i s , t h i s being most evident i n the c a n o n i c a l c o r r e l a t i o n a n a l y s e s . Surface waters on both s i d e s showed g r e a t e r d i v e r s i t y than deeper down, the w e l l - s t r a t i f i e d east with a mixture of d i n o f l a g e l l a t e s and n a n o f l a g e l l a t e s , the l e s s - s t r a t i f i e d west with d i n o f l a g e l l a t e s and diatoms. The MC was a l s o h i g h l y s t r a t i f i e d , due mostly to 228 temperature. As i n the NSG, there was a mixture of d i n o f l a g e l l a t e s and n a n o f l a g e l l a t e s dominating the s u r f a c e waters, while diatoms occupied the deeper r e g i o n s . The s p e c i e s assemblages, however, were very d i f f e r e n t so t h a t , although the same s u c c e s s i o n a l s t r a t e g y was o c c u r r i n g , each area had a t t a i n e d d i f f e r e n t e q u i l i b r i a . Diatoms had g r e a t e r dominance i n the MC in subsurface samples except i n Okeover I n l e t . September was a time when the northern S t r a i t was s t r a t i f i e d more or l e s s evenly except f o r the NW and NE c o r n e r s . The former saw Aat drop due to the t i d a l j e t while the l a t t e r saw v a l u e s almost double the ambient Aat of 2 due to i n t r u s i o n of l e s s s a l i n e water from the northern passages. At no other time had organismal p a t t e r n s been so n e a t l y segregated. The subsurface c o n c e n t r a t i o n s of Chaetoceros had disappeared, to be r e p l a c e d by a west s i d e p o p u l a t i o n of R h i z o s o l e n i a s e t i g e r a . Again, the h e t e r o t r o p h i c n a n o f l a g e l l a t e s were most abundant i n areas of h i g h diatom biomass where e i t h e r a l g a l e x c r e t i o n or c e l l l y s i s might have been o c c u r r i n g . The east s i d e was host to n a n o f l a g e l l a t e s and t h e i r c i l i a t e g r a z e r s . The more s t r a t i f i e d n o r t h was now dominated by the d i n o f l a g e l l a t e s , both p h o t o s y n t h e t i c and h e t e r o t r o p h i c , which may have i n d i c a t e d some form of predator-prey i n t e r a c t i o n . I t i s i n t e r e s t i n g to note t h a t , i n the southwest where R. s e t i g e r a biomass was h i g h e s t , the h e t e r o t r o p h i c d i n o f l a g e l l a t e s were not abundant. F i n a l l y , the middle of the S t r a i t saw c o n c e n t r a t i o n s of M. rubrum and m i s c e l l a n e o u s p h o t o s y n t h e t i c f l a g e l l a t e s , c o n s i s t i n g mostly of Heterosigma akashiwo. 229 Although s t r a t i f i c a t i o n was rather homogeneous throughout the S t r a i t , i t i s obvious that the t i d a l j e t must have been having some e f f e c t on the ecology. The thermocline along Transect 5 broke the s u r f a c e i n the west and would have thus presented a f r o n t a l boundary. On the s t r a t i f i e d s i d e near t h i s f r o n t , d i n o f l a g e l l a t e s were growing w e l l even though s u r f a c e waters were devoid of n i t r a t e . I f ammonium was not a s u f f i c i e n t n i t r o g e n source t h e i r powers of m o t i l i t y would enable them to e x p l o i t the n u t r i c l i n e which was no deeper than 10m. A number of authors have recognised the presence of d i n o f l a g e l l a t e s a s s o c i a t e d with t i d a l f r o n t s i n c l u d i n g H o l l i g a n (1979) and Pingree et a l . (1975). Temperature s t r a t i f i c a t i o n was present a c r o s s the S t r a i t . I s o h a l i n e s tended to slope upward from east to west so that the east s i d e was somewhat l e s s s a l i n e . From the p h y s i c a l data c o l l e c t e d , there were no obvious trends that might e x p l a i n the s e p a r a t i o n of diatoms and n a n o f l a g e l l a t e s . N a n o f l a g e l l a t e s were present on the west s i d e but reduced in numbers, presumably due to some form of i n t e r a c t i o n with diatoms. One can only assume that the t u r b u l e n t energy was g r e a t e r on the west s i d e , h e l p i n g to keep the diatoms i n suspension. Smayda and Boleyn (1966) found that s i n k i n g r a t e s of R. s e t i g e r a were l e s s than those of S. costatum, so that perhaps t h i s was one reason why R. s e t i g e r a was able to dominate the diatom biomass. In a low turbulence environment, one f a c t o r which may play an important r o l e i s that of d i f f u s i o n l i m i t a t i o n (Gavis, 1976). As water motion about a c e l l decreases, the zone of n u t r i e n t 230 d e p l e t i o n surrounding that c e l l becomes l a r g e r and uptake r a t e decreases. Gavis (1976) found that the s m a l l e r the c e l l i s , the l e s s i t i s i n f l u e n c e d by t h i s form of n u t r i e n t l i m i t a t i o n . A l s o , s i n k i n g and swimming are other a d a p t a t i o n s to bypass t h i s phenomenon, so that one would expect i n n u t r i e n t - p o o r water, a small s i z e and the a b i l i t y to move about are p o s i t i v e l y s e l e c t e d . The mosaic of biomass p a t t e r n s i n the NSG d u r i n g September was r a t h e r s t r i k i n g and somewhat re m i n i s c e n t of Margalef's (1958) a r e a l p a t t e r n s of d i v e r s i t y and h e t e r o g e n e i t y i n the Ria of V i g o , Spain. Grontved (1952) found a mosaic p a t t e r n of s p e c i e s i n the southern North Sea where he i d e n t i f i e d s i x major f l o r i s t i c components. Diatom assemblages were a s s o c i a t e d with c o a s t a l areas and a southward A t l a n t i c Current system whereas f l a g e l l a t e s dominated the northern c e n t r a l r e g i o n . Admittedly the southern North Sea i s much l a r g e r than the NSG but i t does show how v a r y i n g turbulence regimes a f f e c t phytoplankton communities. In September, the MC was only s l i g h t l y s t r a t i f i e d , with a Aat of l e s s than 1. Diatoms were q u i t e abundant i n L a n c e l o t I n l e t but the biomass was dominated by M. rubrum. There had been a d i v e r g e n t s p e c i e s response to t u r b u l e n c e . The only r e a l p h y s i c a l d i f f e r e n c e between L a n c e l o t and Okeover I n l e t s was that s a l i n i t y d i f f e r e n c e s were more pronounced i n the former where diatoms were favoured, and temperature d i f f e r e n c e s were gre a t e r i i n the l a t t e r where M. rubrum had bloomed. Increased turbulence c o u l d p o s s i b l y have been due to l a r g e t i d a l ranges at t h i s 231 sampling time or to i n c r e a s i n g f a l l winds. The l a t t e r would have to be a very r e g i o n a l phenomenon though, as the r e g u l a r p a t t e r n seen i n the S t r a i t c o u l d not e x i s t with e x c e s s i v e wind t u r b u l e n c e . 4.4 Phytoplankton Succession The c l a s s i c paradigm of phytoplankton s u c c e s s i o n i n temperate waters i s that n a n o f l a g e l l a t e s dominate i n winter and s p r i n g u n t i l s u f f i c i e n t thermal s t r a t i f i c a t i o n has set i n to reduce the depth of mixing, a f t e r which diatoms bloom and d e p l e t e the mixed l a y e r ' s n i t r a t e . N u t r i e n t l i m i t a t i o n e l i c i t s a s t r o n g s i n k i n g response i n diatoms ( S t e e l e & Yentsch, 1960; Smayda, 1970) which disappear from the upper euphotic zone and are r e p l a c e d by m o t i l e forms, u s u a l l y d i n o f l a g e l l a t e s . F l a g e l l a t e s are favoured because they can migrate down to the n u t r i c l i n e f o r n i t r a t e uptake at night and r i s e d u r i n g the day to areas of high l i g h t . T h i s model i s perhaps too simple f o r the northern S t r a i t of Georgia. N a n o f l a g e l l a t e s were the dominant p h o t o s y n t h e t i c form i n March and A p r i l , composed c h i e f l y of Chrysochromulina s p e c i e s and cryptomonads. These two maintained t h e i r prominence i n t h i s category d u r i n g a l l sampling p e r i o d s . The only other organism approaching comparable biomass l e v e l s was T e t r a s e l m i s i n June. N a n o f l a g e l l a t e s were not p a r t i c u l a r l y favoured by March c o n d i t i o n s ; they were best a b l e to e x p l o i t t h i s regime. T h e i r biomass more than doubled by l a t e summer i n areas of maximal s t r a t i f i c a t i o n , predominantly on the east s i d e . Compared to 232 p h o t o s y n t h e t i c d i n o f l a g e l l a t e s , n a n o f l a g e l l a t e s were c l e a r l y dominant; however, the l a t t e r f l a g e l l a t e s appeared to be responding more to temperature than s t r a t i f i c a t i o n per se. The d i n o f l a g e l l a t e s seemed capable of e x p l o i t i n g n i t r a t e - d e p l e t e , s t r a t i f i e d waters. Diatoms appeared to f o l l o w a d i f f e r e n t schedule than o u t l i n e d by the paradigm. They d i d not bloom i n s p r i n g or e a r l y summer but achieved very high biomass i n August which they maintained, presumably, u n t i l the f a l l d e c l i n e i n p o t e n t i a l p r o d u c t i v i t y , as d e f i n e d by Cushing (1962). I t i s suggested that a f t e r a delayed bloom i n s u r f a c e waters diatoms sank out of n u t r i e n t - d e p l e t e l a y e r s and were maintained at depth i n areas where t i d a l streaming provided s u f f i c i e n t upward v e l o c i t y . O b v i o u s l y , t h i s maintenance was not constant due to v a r y i n g t i d a l energy, as w e l l as d e c l i n i n g l i g h t i r r a d i a n c e . However, there was c o n c e i v a b l y a p e r i o d where subsurface diatom p o p u l a t i o n s c o u l d s u r v i v e . C l a s s i c phytoplankton s u c c e s s i o n i s d i f f i c u l t to apply to the S t r a i t as a whole because there are too many d i s t i n c t regimes a v a i l a b l e at any one time. T h i s r e s u l t s i n a mosaic of organismal groups. The NSG p r o v i d e d enough environmental h e t e r o g e n e i t y that even dur i n g the l e a s t s t r a t i f i e d p e r i o d s sampled b i o l o g i c a l p a r t i t i o n i n g o c c u r r e d . With the exception of June, the mosaic became more pronounced as the seasons e n f o l d e d , p a r t l y because the t h i r d dimension (depth) c o n t r i b u t e d to the environmental d i v e r s i t y . The i n t e r a c t i o n between k i n e t i c t i d a l energy through enclosed passageways i n the n o r t h , s a l i n i t y 233 s t r a t i f i c a t i o n i n the south, and seasonal temperature s t r a t i f i c a t i o n e f f e c t i v e l y c r e a t e d d i f f e r i n g regimes which were e x p l o i t e d by the v a r i o u s groups. In August b i o l o g i c a l p a r t i t i o n i n g was very pronounced and was maintained and strengthened by September, even though s t r a t i f i c a t i o n had become l e s s v a r i a b l e . The o n l y anomaly i n the t r e n d of i n c r e a s i n g mosaicism was the s i t u a t i o n present i n June when a l l the groups except diatoms were co n c e n t r a t e d i n the t i d a l j e t area. By Margalef's convention (1958), June's community s t r u c t u r e i n d i c a t e d an advanced stage of s t a b i l i t y where a l l organisms were m o t i l e and d i n o f l a g e l l a t e s were u b i q u i t o u s . However, at t h i s group l e v e l of r e s o l u t i o n mosaicism was not obvious. During t h i s p e r i o d there was a l s o an unusual phenomenon: c i l i a t e biomass was i n excess of that c o n t r i b u t e d by the p h o t o s y n t h e t i c forms. P o s s i b l y g r a z i n g pressure was so great t h a t environmental h e t e r o g e n e i t y c o u l d not s e l e c t f o r d i f f e r e n t forms. P a s s i v e p l a n k t e r s would seem e s p e c i a l l y v u l n e r a b l e . A l t e r n a t i v e l y , as mentioned p r e v i o u s l y , the S t r a i t c o u l d have a r r i v e d at the f i n a l stage i n s u c c e s s i o n known as a red t i d e . Admittedly i n the NSG Heterosigma akashiwo d i d not reach very high c o n c e n t r a t i o n s , but i t s dominance and p o s s i b l e e f f e c t s on the system's ecology may have q u a l i f i e d i t as a " m i l d " red t i d e , p a r t i c u l a r l y as i t achieved much higher c o n c e n t r a t i o n s w i t h i n the adjacent Sechelt I n l e t system (100,000,000 c e l l s - l i t r e - 1 , Dale et a l . , 1987), r e s u l t i n g i n the death of caged salmon. 234 4.5_ Comparison with Other Areas The most notable d i f f e r e n c e between the northern and southern S t r a i t of Georgia (SSG) i s the la r g e i n f l u e n c e of the Fr a s e r R i v e r on the l a t t e r r e g i o n . Not only does t h i s major freshwater source d i l u t e s u r f a c e l a y e r s i n the SSG, i t a l s o s i g n i f i c a n t l y reduces the l i g h t a v a i l a b l e by i n t r o d u c t i o n of s i l t , e s p e c i a l l y d u r i n g summer f r e s h e t (LeBlond, 1983). Shim (1976) found that there was no s p e c i a l community a s s o c i a t e d with t h i s plume; however, 29 of the 219 diatoms i d e n t i f i e d i n the S t r a i t were int r o d u c e d by the F r a s e r and surrounding r i v e r s . In t h i s study there were few, i f any, introduced freshwater s p e c i e s found i n the NSG. Parsons et a l . (1969) found that phytoplankton biomass measured as c h l o r o p h y l l a was g r e a t e s t at some d i s t a n c e from the Fr a s e r R i v e r plume i n a crescent-shaped p a t t e r n . In t h i s area p r o d u c t i o n was enhanced due to i n c r e a s e d s t r a t i f i c a t i o n . F u r t h e r i n towards the r i v e r mouth t u r b i d i t y was high, e f f e c t i v e l y reducing l i g h t a v a i l a b l e f o r p h o t o s y n t h e s i s . Outside the plume the mixed l a y e r depths were too deep to allow enhanced p r o d u c t i o n . A s i m i l a r "halo" e f f e c t was re p o r t e d by Stockner et a l . (1977) f o r Howe Sound, where h i g h e s t biomass and p r o d u c t i v i t y occurred at the mouth of the Sound. In A p r i l phytoplankton began to grow throughout Howe Sound, but i n c r e a s e d d i s c h a r g e from the Squamish R i v e r i n June f l u s h e d p o p u l a t i o n s seaward. The s i l t - l a d e n r i v e r water l i m i t e d p r o d u c t i o n f o r the remainder of the summer. There were no such t u r b i d i t y e f f e c t s i n the NSG. 235 The most common phytoplankton growth p a t t e r n i n temperate areas u s u a l l y i n v o l v e s s p r i n g and autumn peaks i n abundance, f o r reasons o u t l i n e d e a r l i e r . P h i f e r (1934) found two types of p r o d u c t i o n i n the San Juan A r c h i p e l a g o . The f i r s t he observed i n channels where p r o d u c t i o n s t a r t e d i n mid-May and continued t i l l l a t e September, with two major peaks o c c u r r i n g from l a t e May to e a r l y June and from mid-July to mid-August. The l a t t e r was the l a r g e r (peak = 400 c e l l s - m l " 1 ) . In both blooms a group of two to f i v e s p e c i e s (often Chaetoceros) dominated the biomass. The second type of p r o d u c t i o n he observed i n long narrow bays where pr o d u c t i o n began i n e a r l y March and continued through summer (peak = 2000 c e l l s - m l " 1 ) . In l a t e J u l y , diatom r e s t i n g spores formed and armoured d i n o f l a g e l l a t e s became abundant. The biomass was dominated by a s e r i e s of s i n g l e s p e c i e s , each of which were ephemeral. The d i f f e r e n c e i n these two s t r a t e g i e s was a r e s u l t of t i d a l t u r b u l e n c e being much stronger i n the channels than the bays so that diatoms i n the former region were mixed to deeper l e v e l s and, consequently, d i d not remain i n the p h o t i c zone long enough f o r prolonged growth. Winter et. a l . (1975) a l s o observed f a i r l y even p r o d u c t i o n from March to September, 1966 and 1967, i n a l e s s t i d a l l y a c t i v e r e gion of southern Puget Sound. In the c e n t r a l b a s i n of the Sound, however, there were a number of i n t e n s e blooms between e a r l y May and September. A f e a t u r e of t h i s area i s the net seaward flow of b r a c k i s h water with a deep in f l o w of more s a l i n e water. From model s i m u l a t i o n s i t appeared that the high p r o d u c t i v i t y of Puget Sound was due to p e r s i s t e n t • u p w e l l i n g of 236 n u t r i e n t s and a l g a l seed stock. Blooms grew and d e c l i n e d w i t h i n the b a s i n because of t h i s phenomenon, and winds would remove the p o p u l a t i o n s by h o r i z o n t a l a d v e c t i o n . In Narragansett Bay, Durbin et a_l. ( 1975) found that the 1973 s p r i n g bloom c o n s i s t e d of three peaks. The maximal one o c c u r r e d i n l a t e February and was dominated by Detonula  confervacea, Skeletonema costatum, and T h a l a s s i o s i r a  n o r d e n s k i o e l d i i . A f t e r the d e c l i n e of t h i s p o p u l a t i o n two s u c c e s s i v e peaks were observed: the f i r s t i n e a r l y A p r i l , c o n s i s t i n g of Chaetoceros compressus, Ch. d e c i p i e n s , and Th. n o r d e n s k i o e l d i i , and the second in e a r l y May, comprised of the same two Chaetoceros s p e c i e s , A s t e r i o n e l l a g l a c i a l i s , L e p t o c y l i n d r u s danicus, and L. minimus. T h i s may have been an unusual s p r i n g bloom, though, as S. costatum o f t e n dominates t h i s event ( P r a t t , 1966; Tomas, 1978). N a n o f l a g e l l a t e s and Heterosigma akashiwo p r e v a i l e d throughout the summer u n t i l l a t e August when S. costatum bloomed. Saanich I n l e t ' s 1974 bloom occurred i n mid-May (Takahashi et a l . , 1977), c o n s i s t i n g c h i e f l y of T h a l a s s i o s i r a s p e c i e s (and M i n i d i s c u s , Sancetta, 1988), and l a s t e d two weeks. The autumn bloom was s m a l l e r , o c c u r r i n g at the end of October. By t h i s time Chaetoceros s p e c i e s were dominant; Ditylum b r i g h t w e l l i i was a l s o important. Throughout the summer there were a number of ephemeral peaks due to the o c c a s i o n a l i n t r o d u c t i o n of n i t r a t e from t u r b u l e n c e induced by p e r i o d i c s t r o n g winds, and by freshwater i n t r u s i o n , probably from the F r a s e r R i v e r . Parsons et a l . (1983) r e p o r t e d that i n c r e a s e d t u r b u l e n c e a s s o c i a t e d with 237 s p r i n g t i d e s would a l s o introduce n u t r i e n t s . In Howe Sound, Stockner et. a l . (1977) found that the s p r i n g bloom occu r r e d throughout the Sound i n A p r i l and e a r l y May provided that weather c o n d i t i o n s were good. In June the Squamish River f r e s h e t t r a n s p o r t e d most of the p o p u l a t i o n to the mouth of Howe Sound. T h i s p a t t e r n was evident i n 1973 and T h a l a s s i o s i r a s p e c i e s comprised the v e r n a l bloom. However, i n 1974 weather c o n d i t i o n s were poor, d e l a y i n g the s p r i n g i n c r e a s e (composed c h i e f l y of S. costatum) so that the bloom d i d not occur at the head of the Sound. Autumnal blooms were only observed at the mouth, due to r i v e r d i s c h a r g i n g t u r b i d i t y i n the upper Sound, and were dominated by Chaetoceros s p e c i e s and S. costatum. In the SSG the v e r n a l bloom occurs i n April-May (Shim, 1976) and from l a t e May to e a r l y June halfway up the S t r a i t (Stockner et a l . , 1979). Shim (1976) r e p o r t e d the s p r i n g / f a l l diatom bloom p a t t e r n o f f G a b r i o l a I s l a n d and near Boundary Passage while the more t i d a l l y a c t i v e Haro and Juan de Fuca S t r a i t s maintained s u b s t a n t i a l diatom abundance a l l summer. Stockner et a l . (1979) a l s o r e p o r t e d that the bimodal p a t t e r n of blooms was apparent i n s t r a t i f i e d areas but not i n exposed or t i d a l l y - m i x e d r e g i o n s . The mean annual c h i a and p r o d u c t i v i t y was g r e a t e s t i n the Gulf i s l a n d waterways and l e a s t near the mouth of the F r a s e r River and i n t i d a l l y t u r b u l e n t passageways. I t t h e r e f o r e seems obvious that not a l l areas w i l l e x h i b i t s p r i n g diatom blooms. In the above regions i t was found that t i d a l t u r b u l e n c e can be s u f f i c i e n t to d i s r u p t the c l a s s i c bimodal diatom p a t t e r n . In the NSG there c e r t a i n l y was a degree 238 of t i d a l t u r b u l e n c e , e s p e c i a l l y i n the northwest; however, the e f f e c t of t h i s t urbulence was probably not s u f f i c i e n t to delay the s p r i n g bloom. Rather, exposure to winds was p o s s i b l y the g r e a t e s t f a c t o r . C a s s i e (i960) found that i n Wellingtons Harbour diatom p r o d u c t i o n was g r e a t e r i n l a t e summer and e a r l y autumn than i n s p r i n g due to winds. T h i s p a t t e r n was observed i n the NSG with Chaetoceros s p e c i e s and Skeletonema costatum forming s u b s t a n t i a l late-summer diatom p o p u l a t i o n s . In March and A p r i l n a n o f l a g e l l a t e s were the dominant form, the s p e c i e s composition of which was very s i m i l a r to that found in Saanich I n l e t by Takahashi e_t a_l. (1978) and Watanabe ( 1 978). Sancetta (1988) found that M i n i d i s c u s was an important c o n t r i b u t o r to r e l a t i v e abundance i n the i n l e t d u r i n g winter and e a r l y s p r i n g ; however, due to i t s small s i z e (2-4 um diameter) i t c o n t r i b u t e d minimally to t o t a l biomass. Diatoms were sparse in the NSG at t h i s time and M i n i d i s c u s (which was probably i d e n t i f i e d as a "small T h a l a s s i o s i r a sp.") was not abundant. Malaspina Complex, on the other hand, d i d e x h i b i t the c l a s s i c bimodal p a t t e r n with robust diatom blooms i n March and A p r i l due to i t s s h e l t e r e d nature. The March bloom was c h i e f l y comprised of T h a l a s s i o s i r a e c c e n t r i c a , Chaetoceros d e b i l i s , Th. a e s t i v a l i s , Th. n o r d e n s k i o e l d i i , and Detonula pumila, while A p r i l ' s bloom c o n s i s t e d of N i t z s c h i a p a c i f i c a , Eucampia  zoodiacus, Ch. d e b i l i s , Chrysochromulina spp., and Ch. e i b e n i i . Of i n t e r e s t d u r i n g the f i r s t three sampling times was the e x t r a o r d i n a r i l y h i g h r a t i o of h e t e r o t r o p h i c to photoautotrophic biomass i n the NSG (March = 1.29, A p r i l = 0.61, June = 1.32). 239 Even i f t h i s study had overestimated c i l i a t e biomass, t h i s r a t i o would s t i l l be very h i g h . Takahashi and Hoskins (1978) found that i n Saanich I n l e t microzooplankton were most abundant i n e a r l y winter (Nov-Dec) and s p r i n g (Mar-Apr). Greater than 80% of these organisms were l o c a t e d i n the top 10m. A sample taken from the S t r a i t of Georgia by these authors i n February showed that i n these waters the microzooplankton had a wider v e r t i c a l d i s t r i b u t i o n . A l s o , the t o t a l h e t e r o t r o p h i c protozoan biomass was seven times that found i n Saanich whereas phytoplankton biomass was only two to three times g r e a t e r i n the S t r a i t . A s i m i l a r s i t u a t i o n was found between the NSG and the MC, the l a t t e r area e x h i b i t i n g lower h e t e r o t r o p h i c to p h o t o a u t o t r o p h i c biomass r a t i o s . » Fenchel (1987) r e p o r t e d t h a t , on average, there i s one c i l i a t e per ml of seawater, though s e v e r a l hundred per ml i s not unusual f o r e u t r o p h i c c o a s t a l waters or upwelling zones. In the NSG there was a minimum of 5 c i l i a t e s - m l " 1 i n A p r i l and a maximum of 70 c i l i a t e s - m l " 1 i n June. T h i s l a t t e r c o n c e n t r a t i o n was l o c a t e d i n the t i d a l - j e t a r e a. In J u l y , 1984, P r i c e et a l . (1985) found 1200 ciliates«L" 1 at a f r o n t a l s t a t i o n and 320 c i l i a t e S ' L " 1 at a s t r a t i f i e d s t a t i o n on the west and east s i d e s of the NSG, r e s p e c t i v e l y . These c o n c e n t r a t i o n s are an order of magnitude lower than those observed d u r i n g t h i s study. I t i s apparent that mixing by the t i d a l j e t s t i m u l a t e d production on the west s i d e to which the c i l i a t e s responded. I t seems that c i l i a t e g r a z i n g i s an important f a c t o r i n the NSG. C a p r i u l o and Carpenter (1980) found t h a t microzooplankton i n g e s t e d up to 41% 240 of the s t a n d i n g stock of c h l o r o p h y l l i n Long I s l a n d Sound per day. B u r k h i l l (1982) rep o r t e d that i n a Southampton estuary t i n t i n n i d s may have been consuming 60% of the annual primary p r o d u c t i o n . There i s a l s o the p o s s i b i l i t y that an a p p r e c i a b l e number of the c i l i a t e s i n the NSG, e s p e c i a l l y Strombidium, were capable of r e t a i n i n g t h e i r prey's c h l o r o p l a s t s which might have remained f u n c t i o n a l f o r some time, c o n t r i b u t i n g to c i l a t e p r o d u c t i o n (Blackbourn et a l . , 1973). Stoecker et a l . (1987) observed o l i g o t r i c h o u s c i l i a t e s with sequestered c h l o r o p l a s t s from Woods Hole, Massachusetts. On average, over a year, 42% of the o l i g o t r i c h s had c h l o r o p l a s t s , while d u r i n g the summer up to 90% of the o l i g o t r i c h s c o n t a i n e d c h l o r o p l a s t s . Stoecker e_t a l . (1987) were a l s o able to q u a n t i f y the amount of c i l i a t e carbon f i x e d due to autotrophy. Mixotrophy might t h e r e f o r e e x p l a i n the phenomenal success of c i l i a t e s i n the NSG, e s p e c i a l l y d u r i n g the June sampling. 241 5. CONCLUSIONS 1. The northern S t r a i t of Georgia was most s t r a t i f i e d i n August at which time s u r f a c e n i t r a t e was d e p l e t e d (<1 M M ) and mosaicism of organismal groups was q u i t e pronounced. Diatoms were abundant i n the l e s s s t r a t i f i e d areas where t i d a l streaming was most l i k e l y g r e a t e s t , i . e . , i n the north and along the west s i d e . P h o t o s y n t h e t i c n a n o f l a g e l l a t e s and p h o t o s y n t h e t i c d i n o f l a g e l l a t e s favoured the more s t r a t i f i e d east s i d e . In June the NSG was s t r a t i f i e d but a r e a l b i o l o g i c a l p a r t i t i o n i n g was not e v i d e n t . N i t r a t e was s u f f i c i e n t i n a l l s u r f a c e waters of the NSG at t h i s sampling time so that s e l e c t i o n p r essure may not have been great enough to induce mosaicism. In September s t r a t i f i c a t i o n had decreased and was l e s s v a r i a b l e ; however, the b i o l o g i c a l mosaic set up i n August had been maintained and strengthened. There appeared to be no s i n g l e s u c c e s s i o n a l sequence common to the northern S t r a i t . 2. In g e n e r a l , the east s i d e was more s t r a t i f i e d than the west due to F r a s e r River water i n t r u s i o n from the south along the mainland s i d e and mixing and input of more s a l i n e water from Johnstone S t r a i t by the D i s c o v e r y Passage t i d a l j e t along the Vancouver I s l a n d s i d e . Diatom abundance was u s u a l l y g r e a t e s t along the west s i d e but e l e v a t e d p o p u l a t i o n s were a l s o evident i n the north, p o s s i b l y due to a d v e c t i o n from the n o r t h v i a S u t i l Channel and D e s o l a t i o n Sound. 242 N a n o f l a g e l l a t e s and d i n o f l a g e l l a t e s d i d p r e f e r the east s i d e , but only a f t e r the diatoms had bloomed. 3. During the sampling p e r i o d , i n which no s p r i n g diatom bloom was evident i n the NSG, n a n o f l a g e l l a t e s , d i n o f l a g e l l a t e s , and the miscellaneous p h y t o f l a g e l l a t e s were u s u a l l y more abundant i n s u r f a c e waters whereas the diatoms occ u r r e d deeper down. Depth assemblages were f a i r l y v a r i a b l e i n whatever region was s t u d i e d so that niche s e p a r a t i o n was a f u n c t i o n of depth as w e l l as s t r a t i f i c a t i o n . 4. The Malaspina Complex was expected to be more s t r a t i f i e d than the S t r a i t . T h i s was not the case as the ecology of t h i s complex i s d r i v e n by a t i d a l j e t which prevents strong s t r a t i f i c a t i o n . I t a l s o p o s s i b l y i n j e c t s n u t r i e n t - r i c h water through the well-mixed Malaspina I n l e t to the j u n c t i o n of Malaspina, Okeover, and L a n c e l o t I n l e t s . In s p r i n g the MC was very s h e l t e r e d , a l l o w i n g e a r l y p r o d u c t i o n of diatoms. In summer t h i s complex experienced d e p t h - r e l a t e d b i o l o g i c a l p a r t i t i o n i n g , s i m i l a r to the NSG, but s p e c i e s composition was u s u a l l y s p e c i f i c to t h i s a r ea. In g e n e r a l the MC cannot be used as an i n d i c a t o r of the NSG's ecology. 5. The NSG i s fundamentally d i f f e r e n t from the SSG due to the e x t e n s i v e i n f l u e n c e of the F r a s e r River on the l a t t e r a r e a . T h i s r i v e r i n t r o d u c e s a s i l t y , brackish-water plume which not only a f f e c t s the SSG's l i g h t regime but a l s o p r o v i d e s 2 4 3 early spring s t r a t i f i c a t i o n . The former decreases available l i g h t and, consequently, production within the plume, while the l a t t e r stimulates primary production at the plume's edge in March. The NSG's l i g h t regime was unaffected by t u r b i d i t y , and s t r a t i f i c a t i o n here was predominantly temperature controlled, though surface s a l i n i t i e s were always reduced on the eastern side. Areas of the SSG are subject to strong t i d a l currents which a f f e c t the pattern of phytoplankton succession and the magnitude of production. The NSG was also subject to t i d a l a c t i v i t y ; however, i t s ef f e c t on this area's ecology was more pronounced in summer as wind turbulence probably dominated spring production. 6. The presence of Heterosigma akashiwo in June may have helped suppress diatom production as mixing, nutrient, and l i g h t conditions were a l l favourable to diatom growth at this time. Other toxic species were present in low numbers, such as Protoqonyaulax catenella. 7. C i l i a t e d i s t r i b u t i o n s and possibly those of Gyrodinium indicate that these organisms grazed the nanoflagellates. The close coupling of c i l i a t e and nanoflagellate biomass in space and magnitude suggests that grazing was intense and that nanoflagellate productivity was high. There was a high r a t i o of grazer to food biomass. 8. As a group, Protoperidinium responded to diatom biomass but 244 was not completely dependent on these organisms. They showed a steady i n c r e a s e with s e a s o n a l i t y and were probably g r a z i n g d i n o f l a g e l l a t e s and n a n o f l a g e l l a t e s when diatoms were sparse. 9. P h o t o s y n t h e t i c d i n o f l a g e l l a t e s responded markedly to s t r a t i f i c a t i o n which confirms t h e i r known a b i l i t i e s to e x p l o i t such regimes. 10. Subsurface p o p u l a t i o n s of Chaetoceros i n August were l o c a t e d near the p y c n o c l i n e i n areas of higher t i d a l streaming. T h i s environment may have p r o v i d e d s u f f i c i e n t l i g h t f o r continued growth, with a constant f l u x of n u t r i e n t s v i a entrainment from below the p y c n o c l i n e . 11. H e t e r o t r o p h i c n a n o f l a g e l l a t e s were co n c e n t r a t e d i n areas of higher diatom biomass which suggests they were g r a z i n g b a c t e r i a a s s o c i a t e d with diatom e x c r e t i o n and r e l e a s e of o r g a n i c s . 12. The p h o t o s y n t h e t i c c i l i a t e , Mesodinium rubrum, was most abundant i n regions of mixing, c o n s i s t e n t with i t s known pr e f e r e n c e f o r up w e l l i n g a r e a s . The dynamic regime of Malaspina o f f e r s t h i s h i g h l y m o t i l e p h o t o s y n t h e t i c c i l i a t e o p p o r t u n i t i e s to dominate over t h e i r c h i e f competitors, the diatoms. 245 6. SUGGESTIONS FOR FURTHER RESEARCH 1. The h e t e r o t r o p h i c biomass i n the NSG was very high r e l a t i v e to p hotoautotrophic biomass duri n g s p r i n g and e a r l y summer. C i l i a t e s were e s p e c i a l l y abundant i n June, reaching 70 organisms per ml. I t would be h i g h l y i n f o r m a t i v e to know i f t h i s i s a common fea t u r e of the NSG. Are these c i l i a t e s a r e s u l t of h i g h l y p r o d u c t i v e n a n o f l a g e l l a t e p o p u l a t i o n s maintained by wind turbu l e n c e i n t h i s area? Is c i l i a t e g r a z i n g pressure great enough to h e l p suppress the s p r i n g diatom bloom? To what extent do r e t a i n e d c h l o r o p l a s t s a f f e c t c i l i a t e p r o d u c t i o n ( e x c l u d i n g Mesodinium rubrum)? 2. In northern areas of higher t i d a l streaming i n the NSG there were l a r g e c o n c e n t r a t i o n s of subsurface diatoms. Are these diatoms maintained f o r prolonged p e r i o d s at 10-15 m or are they simply i n the process of s i n k i n g out of n u t r i e n t - d e p l e t e d s u r f a c e waters? Is upward water v e l o c i t y and l i g h t i r r a d i a n c e s u f f i c i e n t at these depths f o r diatoms to grow here? 3. Often biomass i n the NSG was g r e a t e s t i n the t i d a l l y - m i x e d n o r t h . Is t h i s a s t i m u l a t i o n of pr o d u c t i o n i n t h i s area or are p o p u l a t i o n s t r a n s p o r t e d from the northern passages? To what extent do all o c h t h o n o u s p o p u l a t i o n s a f f e c t the NSG v i a Dis c o v e r y Passage, S u t i l Channel, and D e s o l a t i o n Sound i n the north; v i a Baynes Sound and Malaspina S t r a i t i n the south? 246 Seki et a l . (1987) found that due to high f l u s h i n g i n the Campbell R i v e r estuary d u r i n g s p r i n g , s u r f a c e p o p u l a t i o n s were t r a n s p o r t e d out i n t o D i s c o v e r y Passage. T h e r e f o r e , a l l o c h t h o n o u s organic matter may have c o n t r i b u t e d s i g n i f i c a n t l y to the NSG's annual primary p r o d u c t i v i t y . The Malaspina Complex sometimes e x h i b i t e d d i v e r g e n t e c o l o g i e s between Okeover and L a n c e l o t I n l e t s which were separated by the t i d a l j e t e n t e r i n g through Malaspina I n l e t . For example, in September both i n l e t s were e q u a l l y s t r a t i f i e d but Okeover I n l e t was dominated by Mesodinium rubrum while L a n c e l o t I n l e t supported a l a r g e diatom p o p u l a t i o n . Can t h i s d i f f e r e n c e be e x p l a i n e d s o l e l y by turbul e n c e or are there other f a c t o r s involved? What e f f e c t does macrozooplankton have on the NSG? Are copepod numbers indeed reduced here compared to the southern S t r a i t ? I f so, does t h i s a f f e c t the d i s t r i b u t i o n of higher t r o p h i c l e v e l s ? 247 REFERENCES Abe, T.H. 1981. S t u d i e s on the Family P e r i d i n i i d a e . An U n f i n i s h e d Monograph on the Armoured D i n o f l a g e l l a t a . Academia S c i e n t i f i c Book Inc., Tokyo, 411pp. A l l e n , T.F. and J.F. Koonce. 1973. M u l t i v a r i a t e approach to a l g a l stratagems and t a c t i c s i n systems a n a l y s i s of phytoplankton. Ecology, 54: 1234-1246. Ba l c h , W.M. 1981. An apparent lunar t i d a l c y c l e of phytoplankton blooming and community s u c c e s s i o n i n the Gulf of Maine. J . E x p . M a r . B i o l . E c o l . , 55: 65-77. Barnes, H. 1952. The use of t r a n s f o r m a t i o n s i n marine b i o l o g i c a l s t a t i s t i c s . J.Cons.perm.int.Explor.Mer, 18: 61-71. Bary, B.M. 1953. Sea-water d i s c o l o u r a t i o n by l i v i n g organisms. N.Z.J.Sci.Technol., 34B(5): 393-407. Becker, R.A. and J.M. Chambers. 1984. S: An I n t e r a c t i v e Environment for Data A n a l y s i s and G r a p h i c s . Wadsworth Advanced Book Program, Belmont, C a l i f o r n i a , 550pp. Beers, J.R. and G.L. Stewart. 1970. Numerical abundance and estimated biomass of microzooplankton. B u l l . S c r i p p s Inst.Oceanoqr., 17: 67-87. B e l l , W.H. 1980. B a c t e r i a l u t i l i z a t i o n of a l g a l e x t r a c e l l u l a r p r o d u c t s . 2. A k i n e t i c study of n a t u r a l p o p u l a t i o n s . Limnol.Oceanogr., 25(6): 1021-1033. B e l l , W.H., J.M. Lang, and R. M i t c h e l l . 1974. S e l e c t i v e s t i m u l a t i o n of marine b a c t e r i a by a l g a l e x t r a c e l l u l a r p r o d u c t s . Limnol.Oceanogr., 19(5): 833-839. Black, G.R. 1984. Copepod community dynamics i n a h i g h l y v a r i a b l e environment -- The S t r a i t of G e o r g i a . M.Sc. T h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 156pp. 248 Blackbourn, D.J., F.J.R. T a y l o r , and J . Blackbourn. 1973. F o r e i g n o r g a n e l l e r e t e n t i o n by c i l i a t e s . J . P r o t o z o o l . , 20(2): 286-288. B l a c k i t h , R.E. and R.A. Reyment. 1971. M u l t i v a r i a t e Morphometries. Academic Press, London, 412pp. Blas c o , D., M. Estrado, and B. Jones. 1980. R e l a t i o n s h i p between the phytoplankton d i s t r i b u t i o n s and composition and hydrography in the Northwest A f r i c a n u pwelling region near Cabo C o r b e i r o . Deep-Sea Res., 27(10A): 799-821. Brunei, J . 1962. Le Phytoplancton de l a Baie des C h a l e u r s . C o n t r i b u t i o n s du M i n i s t e r e de l a Chasse et des P e c h e r i e s , No.91, Province de Quebec, 365pp. Buchanan, R.J. 1966. A study of s p e c i e s composition and ecology of the protoplankton of a B r i t i s h Columbia i n l e t . Ph.D. T h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 268pp. B u r k h i l l , P.H. 1982. C i l i a t e s and other microplankton components of a nearshore food-web: standing stocks and p r o d u c t i o n p r o c e s s e s . Ann.Inst.Oceanoqr., P a r i s , 58: 335-350. Canadian Hydrographic S e r v i c e . 1983. Current A t l a s : Juan de Fuca S t r a i t to S t r a i t of Georgia. I n s t i t u t e of Ocean S c i e n c e s , P a t r i c i a Bay, B r i t i s h Columbia. C a p r i u l o , G.M. and E . J . Carpenter. 1980. Grazing by 35 to 202 /um microzooplankton i n Long I s l a n d Sound. M a r . B i o l . , 56: 319-326. Caron, D.A., J.C. Goldman, O.K. Andersen, and M.R. Dennett. 1985. N u t r i e n t c y c l i n g i n a m i c r o f l a g e l l a t e food c h a i n . I I . P o p u l a t i o n dynamics and carbon c y c l i n g . Mar.Ecol.Prog.Ser., 24(4): 243-254. Caron, D.A., J.C. Goldman, and M.R. Dennett. 1986. E f f e c t of temperature on growth, r e s p i r a t i o n , and n u t r i e n t r e g e n e r a t i o n by an omnivorous m i c r o f l a g e l l a t e . A p p l . E n v i r o n . M i c r o b i o l . , 52(6): 1340-1347. 249 C a s s i e , V. 1960. Seasonal changes i n diatoms and d i n o f l a g e l l a t e s o f f the east coast of New Zealand d u r i n g 1957 and 1958. N . Z . J . S c i . , 3(1): 137-172. Cooper, R.A. and A.J. Weekes. 1983. Data, Models and S t a t i s t i c a l A n a l y s i s . P h i l i p A l l a n P u b l i s h e r s , L t d . , 400pp. C u l l e n , J . J . , F.M.H. Reid, and E. Stewart. 1982. Phytoplankton in the s u r f a c e and c h l o r o p h y l l maximum o f f southern C a l i f o r n i a i n August, 1978. J.Plankton Res., 4(3): 665-694. Cupp, E.E. 1943. Marine Plankton Diatoms of the West Coast of North America. U n i v e r s i t y of C a l i f o r n i a P r e s s , Berkeley, 237pp. Cushing, D.H. 1962. An a l t e r n a t i v e method of e s t i m a t i n g the c r i t i c a l depth. J.Cons.perm.int.Explor.Mer, 27(2): 131-140. Dale, B., D.G. Baden, B.McK. Bary, L. E d l e r , S. Fraga, I.R. Jenkinson, G.M. H a l l e g r a e f f , T. O k a i c h i , K. Tangen, F.J.R. T a y l o r , A.W. White, CM. Yentsch, and C S . Yentsch. 1987. The problems of t o x i c d i n o f l a g e l l a t e blooms i n a q u a c u l t u r e . Proceedings from a workshop and i n t e r n a t i o n a l conference h e l d at Sherkin I s l a n d marine s t a t i o n , I r e l a n d , 8-13, June, 1987. Pubis. Sherkin I s l a n d Lab. Davis, P.G., D.A. Caron, P.W. Johnson, and J.McN. S i e b u r t h . 1985. Phototrophic and a p o c h l o r o t i c components of p i c o p l a n k t o n and nanoplankton i n the North A t l a n t i c : geographic, v e r t i c a l , s e a s o n a l , and d i e l d i s t r i b u t i o n s . Mar.Ecol.Prog.Ser., 21(1): 15-26. Dewey, J.M. 1976. Rates of f e e d i n g , r e s p i r a t i o n , and growth of the r o t i f e r Brachionus p l i c a t i l i s and the d i n o f l a g e l l a t e Noct i l u c a m i l i a r i s i n the l a b o r a t o r y . Ph.D. T h e s i s , U n i v e r s i t y of Washington, 149pp. Dodge, J.D. 1982. Marine D i n o f l a g e l l a t e s of the B r i t i s h I s l e s . Her Majesty's S t a t i o n e r y O f f i c e , London, 303pp. 250 Durbin, E.G., R.W. Krawiec, and T . J . Smayda. 1975. Seasonal s t u d i e s on the r e l a t i v e importance of d i f f e r e n t s i z e f r a c t i o n s of phytoplankton i n Narragansett Bay (USA). M a r . B i o l . , 32: 271-287. E d l e r , L. 1979. Recommendations f o r marine b i o l o g i c a l s t u d i e s i n the B a l t i c Sea: phytoplankton and c h l o r o p h y l l . N a t i o n a l Swedish Environment P r o t e c t i o n Board, 38pp. Eppley, R.W., 0. Holm-Hansen, and J.D.H. S t r i c k l a n d . 1968. Some ob s e r v a t i o n s on the v e r t i c a l m i g r a t i o n of d i n o f l a g e l l a t e s . J . P h y c o l . , 4: 333-340. Eppley, R.W., F.M.H. Reid, and J.D.H. S t r i c k l a n d . 1970. Estimates of phytoplankton c r o p s i z e , growth r a t e , and primary p r o d u c t i o n . B u l l . S c r i p p s Inst.Oceanogr., 17: 33-42. Eppley, R.W., J.N. Rogers, and J . J . McCarthy. 1969. H a l f - s a t u r a t i o n c o n s t a n t s f o r uptake of n i t r a t e and ammonia by marine phytoplankton. Limnol.Oceanogr., 14(6): 912-920. Est r a d o , M. and D. B l a s c o . 1979. Two phases of the phytoplankton community i n the Baja C a l i f o r n i a u p w e l l i n g . Limnol.Oceanogr., 24(6): 1065-1080. Fenchel, T. 1982. Ecology of h e t e r o t r o p h i c m i c r o f l a g e l l a t e s . IV. Q u a n t i t a t i v e occurrence and importance as b a c t e r i a l consumers. Mar.Ecol.Prog.Ser., 9 ( 1 ) : 35-42. Fenchel, T. 1987. Ecology of Protozoa: The B i o l o g y of F r e e - l i v i n g Phagotrophic P r o t i s t s . Science Tech Pubis., Madison, Wisconsin, 197pp. Fonds, M. and D. Eisma. 1967. Upwelling water as a p o s s i b l e cause of red plankton and blooms along the Dutch c o a s t . Netherlands J.Sea Res., 3(3) : 458-463. F u l t o n , J . 1973. Some asp e c t s of the l i f e h i s t o r y of Calanus  plumchrus i n the S t r a i t of Georgia. J.Fish.Res.Bd.Can., 30: 811-815. 251 Gaines, G. and F.J.R. T a y l o r . 1984. E x t r a c e l l u l a r d i g e s t i o n i n marine d i n o f l a g e l l a t e s . J.Plankton Res., 6(6): 1057-1061. Gaines, G. and F.J.R. T a y l o r . 1986. A m a r i c u l t u r i s t ' s guide to p o t e n t i a l l y harmful marine phytoplankton of the P a c i f i c Coast of North America. Information Report No. 10, Marine Resources S e c t i o n , F i s h e r i e s Branch, B.C. M i n i s t r y of the Environment, 54pp. G a r r i s o n , D.L. 1981. Monterey Bay phytoplankton. I. Seasonal c y c l e of phytoplankton assemblages. J.Plankton Res., 1: 241-265. Gavis, J . 1976. Munk and R i l e y r e v i s i t e d : N u t r i e n t d i f f u s i o n t r a n s p o r t and r a t e s of phytoplankton growth. J.Mar.Res., 34: 161-179. Gieskes, W.W.C. and G.W. Kraay. 1975. The phytoplankton s p r i n g bloom i n Dutch c o a s t a l waters of the North Sea. Neth.J.Sea Res., 9: 166-196. G i l m a r t i n , M. 1964. The primary p r o d u c t i o n of a B r i t i s h Columbia f j o r d . J.Fish.Res.Bd.Can., 21: 505-538. G i t t i n s , R. 1985. Canonical A n a l y s i s . A Review with A p p l i c a t i o n s i n Ecology. Biomathematics, Vol.12, S p r i n g e r - V e r l a g , 3 51pp. Goldman, J . C , and D.A. Caron. 1985. Experimental s t u d i e s on an omnivorous m i c r o f l a g e l l a t e : i m p l i c a t i o n s f o r g r a z i n g and n u t r i e n t r e g e n e r a t i o n i n the marine m i c r o b i a l food c h a i n . Deep-Sea Res., 32: 899-915. Goodman, D., R.W. Eppley, and F.M.H. Reid. 1984. Summer phytoplankton assemblages and t h e i r environmental c o r r e l a t e s i n the Southern C a l i f o r n i a B i g h t . J.Mar.Res., 42: 1019-1049. Grontved, J . 1952. I n v e s t i g a t i o n s on the phytoplankton i n the southern North Sea i n May 1947. Meddelelser f r a Kommissionen f o r Danmarks F i s k e r i - o g Havundersogelser, S e r . ( P l a n k t o n ) , 5(5): 49pp. 252 Haigh, R. 1988. Environmental and b i o l o g i c a l data, northern S t r a i t of Georgia and Malaspina Complex, 1986. Data Report 56, I n s t . Oceanogr., U.B.C. H a l l e g r a e f f , G.M. 1981. Seasonal study of phytoplankton pigments and s p e c i e s at a c o a s t a l s t a t i o n o f f Sydney. Importance of diatoms and the nanoplankton. M a r . B i o l . , 61: 107-118. H a l l e g r a e f f , G.M. and D.D. Reid. 1986. Phytoplankton s p e c i e s s u c c e s s i o n s and t h e i r h y d r o l o g i c a l environment at a c o a s t a l s t a t i o n o f f Sydney. Austr.J.Mar.Freshw.Res., 37(3): 361-377. Hannah, F . J . and A.D. Boney. 1983. Nanophytoplankton i n the F i r t h of Clyde, S c o t l a n d : seasonal abundance, carbon f i x a t i o n and s p e c i e s composition. J . E x p . M a r . B i o l . E c o l . , 67(2): 105-147. H a r r i s o n , P.J., J.D. F u l t o n , F.J.R. T a y l o r , and T.R. Parsons. 1983. Review of the b i o l o g i c a l oceanography of the S t r a i t of G eorgia: p e l a g i c environment. Can . J . F i s h . A g . S c i . , 40: 1064-1094. H a r r i s o n , W.G. 1976. N i t r a t e metabolism of the red t i d e d i n o f l a g e l l a t e Gonyaulax p o l y e d r a S t e i n . J . E x p . M a r . B i o l . E c o l . , 21: 199-209. Hasle, G.R. 1950. P h o t o t a c t i c v e r t i c a l m i g r a t i o n i n marine d i n o f l a g e l l a t e s . Oikos, 2 ( 2 ) : 162-175. Hasle, G.R. 1978. Using the i n v e r t e d microscope. I_n Phytoplankton Manual. Monographs on oceanographic methodology 6, (A. Sournia, ed.), UNESCO pp.191-196. Heinbokel, J.F. 1978. St u d i e s on the f u n c t i o n a l r o l e of t i n t i n n i d s i n the Southern C a l i f o r n i a B i g h t . I. Grazing and growth r a t e s i n l a b o r a t o r y c u l t u r e s . M a r . B i o l . , 47: 177-189. Heinbokel, J.F. and J.R. Beers. 1979. Studie s on the f u n c t i o n a l r o l e of t i n t i n n i d s i n the Southern C a l i f o r n i a B i g h t . I I I . Grazing impact of n a t u r a l assemblages. M a r . B i o l . , 52: 23-32. 253 Hendey, N.I. 1964. An I n t r o d u c t o r y Account of the Smaller Algae of B r i t i s h C o a s t a l Waters. Part V: B a c i l l a r i o p h y c e a e (Diatoms). Her Majesty's S t a t i o n e r y O f f i c e , London, 317pp.+plates. H o l l i g a n , P.M. 1979. D i n o f l a g e l l a t e blooms a s s o c i a t e d with t i d a l f r o n t s around the B r i t i s h I s l e s . I_n Proc.2nd Internat.Conf. on Toxic D i n o f l a g e l l a t e Blooms (D.L. T a y l o r & H.H. S e l i g e r , e d s . ) , E l s e v i e r North H o l l a n d , N.Y., pp.249-256. Holm-Hansen, 0., C.J. Lorenzen, R.W. Holmes, and J.D.H. S t r i c k l a n d . 1965. F l u o r o m e t r i c d e t e r m i n a t i o n of c h l o r o p h y l l . J.Cons.perm.int.Explor.Mer, 30(1): 3-15. Holm-Hansen, 0. and B. Riemann. 1978. C h l o r o p h y l l a d e t e r m i n a t i o n : improvements i n methodology. Oikos, 30: 438-447. Holmes, R.W. and T.M. W i d r i g . 1956. The enumeration and c o l l e c t i o n of marine phytoplankton. J.Cons.perm.int.Explor.Mer, 22(1): 21-32. Hustedt, F. 1985. The Pennate Diatoms, a t r a n s l a t i o n of Hustedt's "Die K i e s e l a l g e n , 2 . T e i l " with supplement by N.G. Jensen. K o e l t z S c i e n t i f i c Books, K o e n i g s t e i n , 918pp. Ibanez, F. and F. Rassoulzadegan. 1977. A study of the r e l a t i o n s h i p s between p e l a g i c c i l i a t e s ( 0 1 i g o t r i c h i n a ) and p l a n k t o n i c n a n o f l a g e l l a t e s of the n e r i t i c ecosystem of the bay of V i l l e f r a n c h e - s u r - M e r . A n a l y s i s of c h r o n o l o g i c a l s e r i e s . Ann.Inst.Oceanogr., Par i s , 53: 17-30. Jacobson, D.M. and D.M. Anderson. 1986. Thecate h e t e r o t r o p h i c d i n o f l a g e l l a t e s : feeding behaviour and mechanisms. J. P h y c o l . , 22(3): 249-258. Kaneta, P.J., M. Levandowsky, and W. E s a i a s . 1985. M u l t i v a r i a t e a n a l y s i s of the phytoplankton community i n the New York B i g h t . Mar.Ecol.Prog.Ser., 23: 231-239. 254 K e s s e l e r , H. 1966. B e i t r a g zur kenntnis der chemischen und p h y s i k a l i s c h e n E i g e n s c h a f t e n des Z e l l s a f r e s von N o c t i l u c a  m i l i a r i s . V e r o f f . I n s t . M e e r e s f o r s c h . Bremerhaven, pp.357-368. LeBlond, P.H. 1983. The S t r a i t of Georgia: f u n c t i o n a l anatomy of a c o a s t a l sea. C a n . J . F i s h . A g . S c i . , 40(7): 1033-1063. Lindholm, T. 1985. Mesodinium rubrum -- a unique p h o t o s y n t h e t i c c i l i a t e . I_n Advances i n Aquatic M i c r o b i o l o g y , V o l . 3 : 1-48, (H.W. Jannasch and P.J.LeB. W i l l i a m s , e d s . ) , Academic Press, 335pp. L i n l e y , E.A.S., R.C. Newell, and M.I. Lucas. 1983. Q u a n t i t a t i v e r e l a t i o n s h i p s between phytoplankton, b a c t e r i a and h e t e r o t r o p h i c m i c r o f l a g e l l a t e s i n s h e l f waters. Mar.Ecol.Prog.Ser., 12: 77-89. Lorenzen, C.J. 1967. V e r t i c a l d i s t r i b u t i o n of c h l o r o p h y l l and phaeo-pigments: Baja C a l i f o r n i a . Deep-Sea Res., 14(6): 735-746. Lund, J.W.G., C. K i p l i n g , and E.D. LeCren. 1958. The i n v e r t e d microscope method of e s t i m a t i n g a l g a l numbers and the s t a t i s t i c a l b a s i s of e s t i m a t i o n s by c o u n t i n g . H y d r o b i o l o g i a , 11(2): 143-170. McCarthy, J . J . , W. Rowland T a y l o r , and M.E. L o f t u s . 1974. S i g n i f i c a n c e of nanoplankton i n the Chesapeake Bay e s t u a r y and problems a s s o c i a t e d with the measurement of nanoplankton p r o d u c t i v i t y . M a r . B i o l . , 24: 7-16. Mackas, D.L., G.C. L o u t t i t , and M.J. A u s t i n . 1980. S p a t i a l d i s t r i b u t i o n of zooplankton and phytoplankton i n B r i t i s h Columbian c o a s t a l waters. Can.J.Fish.Ag.Sci., 37: 1476-1487. Malone, T.C. 1971a. The r e l a t i v e importance of nannoplankton and netplankton as primary producers i n the C a l i f o r n i a Current system. F i s h . B u l l . U . S . , 69: 799-820. 255 Malone, T.C. 1971b. The r e l a t i v e importance of nannoplankton and netplankton as primary producers i n t r o p i c a l oceanic and n e r i t i c phytoplankton communities. Limnol.Oceanogr., 16: 633-639. Margalef, R. 1958. Temporal s u c c e s s i o n and s p a t i a l h e t e r o g e n e i t y i n p l a n k t o n . I_n P e r s p e c t i v e s i n Marine B i o l o g y , (A.A. B u z z a t i - T r a v e r s o , ed.), U n i v e r s i t y of C a l i f o r n i a P r ess, Berkeley, pp.323-349. Margalef, R. 1963. Succession i n marine p o p u l a t i o n s . A d v g . F r o n t i e r s P i . S c i . , New D e h l i , 2: 137-188. Margalef, R. 1978. L i f e - f o r m s of phytoplankton as s u r v i v a l a l t e r n a t i v e s i n an unstable environment. Oceanol.Acta, 1: 493-509. Margalef, R., M. E s t r a d a , and D. B l a s c o . 1979. F u n c t i o n a l morphology of organisms i n v o l v e d i n red t i d e s , as adopted to decaying t u r b u l e n c e . I_n Proc.3rd I n t e r n a t .Conf. on Toxic D i n o f l a g e l l a t e Blooms (D.L. T a y l o r and H.H. S e l i g e r , e d s . ) , E l s e v i e r / N o r t h H o l l a n d , New York, pp.89-94. M a r s h a l l , P.T. 1958. Primary p r o d u c t i o n i n the A r c t i c . J.Cons.perm.int.Explor.Mer, 23: 173-177. Matta, J.F. and H.G. M a r s h a l l . 1984. A m u l t i v a r i a t e a n a l y s i s of phytoplankton assemblages i n the western North A t l a n t i c . J.Plankton Res., 6 ( 4 ) : 663-675. Mommaerts, J.-P. 1973. The r e l a t i v e importance of nannoplankton i n the North Sea primary p r o d u c t i o n . B r . P h y c o l . J . , 8: 13-20. Oakley, B.R. and F.J.R. T a y l o r . 1978. Evidence f o r a new type of symbiotic a s s o c i a t i o n i n a p o p u l a t i o n of the c i l i a t e Mesodinium rubrum from B r i t i s h Columbia. BioSystems, 10: 361-369. Paasche, E. 1960. On the r e l a t i o n s h i p between primary p r o d u c t i o n and standing stock of phytoplankton. J.Cons.perm.int.Explor.Mer, 26(1): 33-48. 256 Parsons, T.R. and R.J. LeBrasseur. 1968. A d i s c u s s i o n of some c r i t i c a l i n d i c e s of primary and secondary p r o d u c t i o n f o r l a r g e - s c a l e ocean surveys. Ca1if.Mar.Res.Comm., CalCOFI  Rept., 12: 54-63. Parsons, T.R., R.J. LeBrasseur, and W.E. Ba r r a c l o u g h . 1970. L e v e l s of pro d u c t i o n i n the p e l a g i c environment of the S t r a i t of Georgia, B r i t i s h Columbia: a review. J.Fish.Res.Bd.Can., 27: 1251-1264. Parsons, T.R., Y. Maita, and CM. L a l l i . 1984. A Manual of Chemical and B i o l o g i c a l Methods f o r Seawater A n a l y s i s . Pergamon Press, 173pp. Parsons, T.R., R.I. Perry, E.D. Nutbrown, W. Hsieh, and C M . L a l l i . 1983. F r o n t a l zone a n a l y s i s at the mouth of Saanich I n l e t , B r i t i s h Columbia. Mar.Bio1., 73: 1-5. Parsons, T.R., K. Stephens, and R.J. LeBrasseur. 1969. Pro d u c t i o n s t u d i e s i n the S t r a i t of Georgia. I. Primary p r o d u c t i o n under the Fr a s e r River plume. February to May, 1967. J.Exp.Mar.Biol.Ecol., 3: 27-38. Parsons, T.R., J . Stronach, G.A. Borstad, G. L o u t t i t , and R.I. P e r r y . 1981. B i o l o g i c a l f r o n t s i n the S t r a i t of Georgia, B r i t i s h Columbia, and t h e i r r e l a t i o n to recent measurements of primary p r o d u c t i v i t y . Mar.Ecol.Prog.Ser., 6(3 ) : 237-242. Perry, R.I., B.R. D i l k e , and T.R. Parsons. 1983. T i d a l mixing and summer plankton d i s t r i b u t i o n s i n Hecate S t r a i t , B r i t i s h Columbia. Can.J.Fish.Ag.Sci., 40: 871-887. P h i f e r , L.D. 1934. P e r i o d i c i t y of diatom growth i n the San Juan A r c h i p e l a g o . Proc.5th Pac.Sci.Cong., pp.2047-2049. Pimentel, R.A. 1979. Morphometries: The M u l t i v a r i a t e A n a l y s i s of B i o l o g i c a l Data. Kendall/Hunter, 276pp. Pingree, R.D. 1978. Mixing and s t a b i l i z a t i o n of phytoplankton d i s t r i b u t i o n s on the northwest European c o n t i n e n t a l s h e l f . In S p a t i a l P a t t e r n i n Plankton Communities (J.H. S t e e l e , ed.), NATO Conf. S e r i e s , IV Marine S c i e n c e s , 3: 181-238, Plenum Press, N.Y., 470pp. 257 Pingree, R.D., P.M. H o l l i g a n , and G.T. M a r d e l l . 1978. The e f f e c t s of v e r t i c a l s t a b i l i t y on phytoplankton d i s t r i b u t i o n s i n the summer on the Northwest European S h e l f . Deep-Sea Res., 25: 1011-1028 Pingree, R.D., P.M. H o l l i g a n , G.T. M a r d e l l , and R.N. Head. 1976. The i n f l u e n c e of p h y s i c a l s t a b i l i t y on s p r i n g , summer, and autumn phytoplankton blooms i n the C e l t i c Sea. J.Mar.Biol.Ass.U.K., 55: 845-873. Pingree, R.D., P.R. Pugh, P.M. H o l l i g a n , and G.R. F o s t e r . 1975. Summer phytoplankton blooms and red t i d e s along t i d a l f r o n t s i n the approaches to the E n g l i s h Channel. Nature, 258: 672-677. P r a t t , D. 1966. Competition between Skeletonema costatum and O l i s t h o d i s c u s l u t e u s i n Narragansett Bay and i n c u l t u r e . Limnol.Oceanogr., 11: 447-455. P r i c e , N.M., W.P. Cochlan, and P.J. H a r r i s o n . 1985. Time course of uptake of i n o r g a n i c and organic n i t r o g e n by phytoplankton i n the S t r a i t of Georgia: comparison of f r o n t a l and s t r a t i f i e d communities. Mar.Ecol.Prog.Ser., 27: 39-53. P r o v a s o l i , L. 1979. Recent p r o g r e s s , an overview. In Proc.2nd I n t r e r n a t . C o n f . on Toxic D i n o f l a g e l l a t e Blooms (D.L. T a y l o r and H.H. S e l i g e r , e d s . ) , E l s e v i e r / N o r t h - H o l l a n d , N.Y., 1-14. Reid, F.M.H., E. F u g l i s t e r , and J.B. Jordan. 1970. Phytoplankton taxonomy and standing crop. B u l l . S c r i p p s Inst.Oceanogr., 17: 51-66. Reid, F.M.H., E. Stewart, R.W. Eppley, and D. Goodman. 1978. S p a t i a l d i s t r i b u t i o n of phytoplankton s p e c i e s i n c h l o r o p h y l l maximum l a y e r s o f f southern C a l i f o r n i a . Limnol.Oceanogr., 23(2): 219-226. R i c k l e f s , R.E. 1973. Ecology. Chiron Press, Inc., New York, 861pp. 258 R i l e y , G.A. 1942. The r e l a t i o n s h i p of v e r t i c a l t urbulence and s p r i n g diatom f l o w e r i n g s . J.Mar.Res., 5: 67-87. Rodhe, W., R.A. V o l l e n w e i d e r , and A. Nauwerck. 1958. The primary p r o d u c t i o n and standing crop of phytoplankton. In P e r s p e c t i v e s i n Marine B i o l o g y (A.A. B u z z a t i - T r a v e r s o , ed.), U n i v e r s i t y of C a l i f o r n i a Press, Berkeley, pp. 299-322. Ryther, J.H. 1956. P h o t o s y n t h e s i s i n the oceans as a f u n c t i o n of l i g h t i n t e n s i t y . Limnol.Oceanogr., 1: 61-70. Ryther, J.H. 1967. Occurrence of red water o f f Peru. Nature, 214: 1318-1319. Ryther, J.H. and J.G. Sanders. 1980. Experimental evidence of zooplankton c o n t r o l of the s p e c i e s composition and s i z e d i s t r i b u t i o n of marine phytoplankton. Mar.Ecol.Prog.Ser., 3: 279-283. Sakshaug, E. and S. Myklestad. 1973. S t u d i e s on the phytoplankton ecology of the Trondheimsfjord. I I I . Dynamics of phytoplankton blooms i n r e l a t i o n to environmental f a c t o r s , b i o a s s a y experiments and parameters f o r the p h y s i o l o g i c a l s t a t e of the p o p u l a t i o n s . J . E x p . M a r . B i o l . E c o l . , 11: 157-188. Sancetta, C. 1988. V e r t i c a l f l u x of diatom assemblages i n Saanich I n l e t , B r i t i s h Columbia. Deep-Sea Res., ( i n p r e s s ) . S c h i l l e r , J . 1933,1937. D i n o f l a g e l l a t a e ( P e r i d i n e a e ) In Kryptogamen-Flora von Deutschland, O s t e r r e i c h und der Schweiz (L. Rabenhorst, ed.), Akademische V e r l a g s g e s e l l s c h a f t M.B.H., L e i p z i g , 10(3/1): 617pp., 10(3/2): 589pp. S e a l , H.L. 1964. M u l t i v a r i a t e s t a t i s t i c a l a n a l y s i s f o r b i o l o g i s t s . Methuen, London. S e k i , H., A. O t s u k i , Y. Hara, K.V. Stephens, C D . Levings, and C D . M c A l l i s t e r . 1987. Dynamics of o r g a n i c m a t e r i a l s i n the Campbell R i v e r Estuary at the time of the s p r i n g bloom of phytoplankton. A r c h . H y d r o b i o l . , 111(2): 209-216. 259 Semina, J.H. 1960. The i n f l u e n c e of v e r t i c a l c i r c u l a t i o n on the phytoplankton of the B e r i n g Sea. Int.Revue Ges.Hydrobiol., 45: 1-10. Shim, J.H. 1976. D i s t r i b u t i o n and taxonomy of p l a n k t o n i c marine diatoms i n the S t r a i t of Georgia, B.C. Ph.D T h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 272pp. Shim, J.H. 1977. A taxonomic study of marine p l a n k t o n i c diatoms of Vancouver I s l a n d c o a s t a l waters. P r o c . C o l l . N a t u r . S c i . , SNU, 2 ( 2 ) : 79-184. Simpson, J.H. and J.R. Hunter. 1974. F r o n t s i n the I r i s h Sea. Nature, 250: 404-406. Simpson, J.H., P.B. T e t t , M.L. Argote-Espinoza, A. Edwards, K.J. Jones, and G. Savidge. 1982. Mixing and phytoplankton growth around an i s l a n d i n a s t r a t i f i e d sea. Cont.Shelf Res., 1(1): 15-31. S k j o l d a l , H.R. and C. Lannergren. 1978. The s p r i n g phytoplankton bloom i n Ladaspollene, a l a n d - l o c k e d Norwegian f j o r d . I I . Biomass and a c t i v i t y of net- and nanoplankton. M a r . B i o l . , 47: 313-323. Smayda, T.J . 1970. The suspension and s i n k i n g of phytoplankton i n the sea. Oceanogr.Mar.Biol.Ann.Rev., 8: 353-414. Smayda, T . J . 1978. From p h y t o p l a n k t e r s to biomass. I_n Phytoplankton Manual. Monographs on oceanographic methodology 6 (A. Sournia, ed.), UNESCO, pp.273-279. Smayda, T.J . and B.J. Boleyn. 1966. Experimental o b s e r v a t i o n s on the f l o t a t i o n of marine diatoms. I I . Skeletonema costatum and R h i z o s o l e n i a s e t i g e r a . Limnol.Oceanogr., 11: 18-34. Smetacek, V. 1981. The annual c y c l e of protozooplankton i n the K i e l B i g h t . M a r . B i o l . , 63: 1-11. Sorokin, Yu.I. 1977. The h e t e r o t r o p h i c phase of plankton s u c c e s s i o n i n the Japan Sea. M a r . B i o l . , 41(2): 107-117. 260 S t e e l e , J.H. and C.S. Yentsch. 1960. The v e r t i c a l d i s t r i b u t i o n of c h l o r o p h y l l . J.Mar.Biol.Ass.U.K., 39: 217-226. Stephens, K., J.D. F u l t o n , and O.D. Kennedy. 1969. Summary of b i o l o g i c a l oceanographic o b s e r v a t i o n s i n the S t r a i t of Georgia, 1965-1968. Fish.Res.Bd.Can.Tech.Rep., 110: 93pp. Stockner, J.G., D.D. C l i f f , and D.B. Buchanan. 1977. Phytoplankton p r o d u c t i o n and d i s t r i b u t i o n i n Howe Sound, B r i t i s h Columbia: a c o a s t a l marine embayment-fjord under s t r e s s . J.Fish.Res.Bd.Can., 34(7): 907-917. Stockner, J.G., D.D. C l i f f , and K.R.S. Shortr e e d . 1979. Phytoplankton ecology of the S t r a i t of Georgia, B.C. J.Fish.Res.Bd.Can., 36: 657-666. Stoecker, D.K., A.E. M i c h a e l s , and L.H. Da v i s . 1987. Large p r o p o r t i o n of marine p l a n k t o n i c c i l i a t e s found t o c o n t a i n f u n c t i o n a l c h l o r o p l a s t s . Nature, 326(6115): 790-792. Strathmann, R.R. 1967. E s t i m a t i n g the org a n i c carbon content of phytoplankton from c e l l volume or plasma volume. Limnol.Oceanogr., 12(3): 411-418. Stronach, J . 1982. T i d a l and r e s i d u a l c u r r e n t s i n the S t r a i t of Georgia -- S t r a i t of Juan de Fuca system. Prepared f o r Supply and S e r v i c e s Canada by Beak C o n s u l t a n t s , L t d . , Vancouver, B r i t i s h Columbia. S t u c c h i , D.J. 1 980. The t i d a l j e t i n Rupert-Holberg I n l e t . I_n F j o r d Oceanography (H.J. F r e e l a n d , D.M. Farmer, & C.D.Levings, ed s . ) , NATO Conf. S e r i e s , IV Marine S c i e n c e s , 4: 491-497, Plenum Press, N.Y., 715pp. Sverdrup, H.U. 1953. On c o n d i t i o n s f o r the v e r n a l blooming of phytoplankton. J.Cons.perm.int.Explor.Mer, 18: 287-295. Taguchi, S. 1976. R e l a t i o n s h i p between p h o t o s y n t h e s i s and c e l l s i z e of marine diatoms. J . P h y c o l . , 12(2): 185-189. 261 Takahashi, M., J . B a r w e l l - C l a r k e , F. Whitney, and P. K o e l l e r . 1978. Winter c o n d i t i o n s of marine plankton p o p u l a t i o n s i n Saanich I n l e t , B.C., Canada: I. Phytoplankton and i t s surrounding environment. J . E x p . M a r . B i o l . E c o l . , 31: 283-301 . Takahashi, M. and K.D. Hoskins. 1978. Winter c o n d i t i o n of marine plankton p o p u l a t i o n s i n Saanich I n l e t , B.C., Canada. I I . Micro-zooplankton. J . E x p . M a r . B i o l . E c o l . , 32: 27-37. Takahashi, M., D.L. S e i b e r t , and W.H. Thomas. 1977. O c c a s i o n a l blooms of phytoplankton d u r i n g summer i n Saanich I n l e t , B r i t i s h Columbia. Deep-Sea Res., 24: 775-780. T a y l o r , F.J.R., D.J. Balckbourn, and J . Blackbourn. 1969. U l t r a s t r u c t u r e of the c h l o r o p l a s t s and a s s o c i a t e d s t r u c t u r e s w i t h i n the marine c i l i a t e Mesodinium rubrum (Lohmann). Nature, 224(5221): 819-821. T a y l o r , F.J.R., D.J. Blackbourn, and J . Blackbourn. 1971. The red water c i l i a t e Mesodinium rubrum and i t s "incomplete symbionts": a review i n c l u d i n g new u l t r a s t r u c t u r a l o b s e r v a t i o n s . J.Fish.Res.Bd.Can., 28(3): 391-407. Tomas, C R . 1978. O l i s t h o d i s c u s l u t e u s (Chrysophyceae). I. E f f e c t s of s a l i n i t y and temperature on growth, m o t i l i t y and s u r v i v a l . J . P h y c o l . , 14(3): 309-313. Tomas, C R . 1980. O l i s t h o d i s c u s l u t e u s (Chrysophyceae). V. I t s occurrence, abundance and dynamics i n Narragansett Bay, Rhode I s l a n d . J . P h y c o l . , 16: 157-166. T u l l y , J.P. and A.J. Dodimead. 1957. P r o p e r t i e s of the water i n the S t r a i t of Georgia, B r i t i s h Columbia, and i n f l u e n c i n g f a c t o r s . J.Fish.Res.Bd.Can., 14: 241-319. V a l e n t i n , J.L., N.M.L. d a S i l v a , and C B . Bastos. 1985. Les diatomees dans l ' u p w e l l i n g de Cabo F r i o ( B r e s i l ) : l i s t e d'especes et etude e c o l o g i q u e . J.Plankton Res., 7 ( 3 ) : 313-337. 262 V e n r i c k , E.L. 1978. How many c e l l s to count? In. Phytoplankton Manual. Monographs on oceanographic methodology 6 (A. Sournia, ed. ) , UNESCO, pp.167-180. Waldichuk, M. 1957. P h y s i c a l oceanography of the S t r a i t of Georgia, B r i t i s h Columbia. J.Can.Res.Bd.Can., 14: 321-486. Watanabe, L.N. 1976. T h e o r e t i c a l and p r a c t i c a l a spects of n a n o p h y t o f l a g e l l a t e taxonomy and ecology on the B r i t i s h Columbia c o a s t . Unpublished Manuscript, 206pp. Watanabe, L.N. 1978. F a c t o r s c o n t r o l l i n g the winter dominance of n a n o f l a g e l l a t e s i n Saanich I n l e t . M.Sc. T h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 104pp. Winter, D.F., K. Banse, and G.C. Anderson. 1975. The dynamics of phytoplankton blooms i n Puget Sound, a f j o r d i n the northwestern U n i t e d S t a t e s . M a r . B i o l . , 29: 139-176. Wood, E.D., F.A.J. Armstrong, and F.A. Ri c h a r d s . 1967. Determination of n i t r a t e i n seawater by cadmium-copper r e d u c t i o n to n i t r i t e . J.Mar.Biol.Ass.U.K., 47: 23-31. Wujek, D.E. 1966. Seasonal v a r i a t i o n i n number and volume of plankton diatoms. Trans.Amer.Microsc.Soc., 85(4): 541-547. Yentsch, C S . and D.W.Menzel. 1963. A method f o r the deter m i n a t i o n of phytoplankton c h l o r o p h y l l and phaeophytin by f l u o r e s c e n c e . Deep-Sea Res., 10: 221-231. APPENDIX 1. SPECIES OF THE NSG AND MC Table 23 on the f o l l o w i n g pages c o n t a i n s most of the spe c i e s observed d u r i n g t h i s study. For s t a t i s t i c a l purposes number of the r a r e r enumerated s p e c i e s were put i n t o more general c a t e g o r i e s . Data are a v a i l a b l e i n Haigh (1988). O r i g i n a l Code = Code as s i g n e d to the s p e c i e s while c o u n t i n g . Used Code = Code used i n the s t a t i s t i c a l a n a l y s e s . Bac i = B a c i l i a r i o p h y c e a e Chry = Chrysophyceae C i l i = C i l i o p h o r a (Phylum) Cras = Craspedophyceae Cryp = Cryptophyceae Dino = Dinophyceae Eugl = Euglenophyceae Pras Prasinophyceae Prym = Prymnesiophyceae Raph = Raphidophyceae S i l i = S i l i c o p h y c e a e PS/Het: P h o t o s y n t h e t i c or H e t e r o t r o p h i c 264 TABLE 23. Organisms observed i n the NSG and MC. Organisms O r i g i n a l Used C l a s s PS/ Observed Code Code Het A c t i n o p t y c h u s undulatus Actund Actund Baci P Alexandrium o s t e n f e l d i i Alexan Alexan Dino P Amphidinium sphenoides Ampsph Amph i d Dino H Amphidinium stigmatum Ampsti Amph i d Dino H A p e d i n e l l a s p i n i f e r a Apedin Apedin Chry P A s t e r i o n e l l a g l a c i a l i s A s t g l a A s t g l a Baci P C e n t r i c diatoms, u n i d e n t i f i e d C e n t r i C e n t r i Baci P C e r a t a u l i n a p e l a g i c a C e r p e l C e r p e l Baci P Ceratium fusus Cerfus C e r a t i Dino P Ceratium lineatum C e r l i n C e r a t i Dino P Ceratium l o n g i p e s C e r l o n C e r a t i Dino P Chaetoceros anastomosans Chaana Chaeto Bac i P Chaetoceros compressus Chacom Chacom Bac i P Chaetoceros c o n s t r i c t u s Chacst Chacst Baci P Chaetoceros convolutus Chacnv Chacnv Bac i P Chaetoceros d e b i l i s Chadeb Chadeb Baci P Chaetoceros d e c i p i e n s Chadec Chadec Baci P Chaetoceros e i b e n i i Chaeib Chaeib Baci P Chaetoceros l a c i n i o s u s Chalac Chalac Baci P Chaetoceros s o c i a l i s Chasoc Chasoc Baci P Chaetoceros s u b t i l i s Chasub Chaeto Baci P Chaetoceros spp. Chaeto Chaeto Baci P C h o a n o f l a g e l l a t e s Choano Choano Cras H Chrysochromulina spp. Chryso Chryso Prym P C i l i a t e , u n i d e n t i f i e d Fuzzba Fuzzba C i l i P C i l i a t e s , h e t e r o t r o p h i c C i l i a t C i l i a t C i l i H Corethron c r i o p h i l u m C o r c r i C o r c r i Baci P Corymbellus aureus Corymb Corymb Prym P C o s c i n o d i s c u s spp. Cos c i n Cose i n Baci P C o s c i n o d i s c u s w a i l e s i i Coswai Coswai Baci P Cryptomonads Crypto Crypto Cryp P C y l i n d r o t h e c a spp. C y l i n d C y l i n d Baci P Detonula pumila Detpum Detpum Baci P D i c r a t e r i a sp. D i c r a t D i c r a t Prym P D i c t y o c h a speculum Dicspe Die spe S i l i P Dinobryon sp. Dinobr Dinobr Chry P D i n o f l a g e l l a t e , sm.thecate Gymn11 Glenod Dino P D i n o f l a g e l l a t e , u n i d e n t i f i e d B a l l o o B a l l o o Dino P D i n o p h y s i s acuminata Dinacm Dinoph Dino P Dinophysis f o r t i i D i n f o r Dinoph Dino P D i n o p h y s i s hast a t a Dinhas Dinoph Dino P Dinophysis norvegica Dinnor Dinoph Dino P 265 TABLE 23. Organisms observed i n the NSG and MC. Organisms O r i g i n a l Used C l a s s PS/ Observed Code Code Het Dinophysis ovum Dinovu Dinoph Dino P Dinophysis parvum Dinpar Dinoph Dino P Dinophysis rotundata D i n r o t Dinoph Dino H D i p l o p s a l i s rotunda D i p r o t D i p l o p Dino H D i p l o p s a l o i d s D i p l o p D i p l o p Dino H D i p l o p s a l o p s i s minor Dipmin D i p l o p Dino H Dissodinium pseudolunula Dispse Dispse Dino H Ditylum b r i g h t w e l l i i D i t b r i D i t b r i Bac i P E b r i a t r i p a r t i t a E b r i a E b r i a S i l i H E n s i c u l i f e r a sp. E n s i c u E n s i c u Dino P Eucampia zoodiacus Euczoo Euczoo Bac i P E u t r e p t i e l l a 68 Eutr68 Eutrep Eugl P E u t r e p t i e l l a 76 Eutr76 Eutrep Eugl P F l a g e l l a t e s , u n i d e n t i f i e d Unknow Unknow -- -F r a g i l a r i a spp. F r a g i l F r a g i l Baci P Gonyaulax d i g i t a l e Gondig Gonyau Dino P Gonyaulax g r i n d l e y i Gongri Gonyau Dino P Gonyaulax polyedra Gonpol Gonyau Dino P Gonyaulax s c r i p p s a e Gonscr Gonyau Dino P Gonyaulax s p i n i f e r a Gonspi Gonyau Dino P Gonyaulax t r i a c a n t h a G o n t r i Gonyau Dino P Gonyaulax v e r i o r Gonver Gonyau Dino P Grammatophora marina Gramar Gramar Bac i P Gymnodinium sanguineum Gymsan Gymnod Dino P Gymnodinium simplex Gymsim Gymnod Dino P Gymnodinoids Gymnod Gymnod Dino P Gyrodinium 65 Gyro65 Gyrodi Dino H Gyrodinium glaucum Gyrg l a Gyrodi Dino H Gyrodinium sp., o v a l Gyrova Gyrodi Dino P Gyrodinium s p i r a l e G y r s p i Gyrodi Dino H Heterocapsa t r i q u e t r a H e t t r i H e t t r i Dino P Heteromastix sp. Hetmas Hetmas Pras P Heterosigma akashiwo Hetaka Hetaka Raph P Katodinium rotundatum Katodi Katodi Dino P Ko f o i d i n i u m v e l l e l o i d e s K o f v e l K o f v e l Dino H L e p t o c y l i n d r u s danicus Lepdan Leptoc Bac i P L e p t o c y l i n d r u s minimus Lepmin Leptoc Baci P Licmophora spp. Licmop Licmop Bac i P M e l o s i r a m o n i l i f o r m i s Melmon Melmon Bac i P Mesodinium rubrum Mesrub Mesrub C i l i P Micracanthodinium sp. Micrac Micrac Dino P Micromonas p u s i l l a Microm Microm Pras P 266 TABLE 23. Organisms observed i n the NSG and MC. Organisms O r i g i n a l Used C l a s s PS/ Observed Code Code Het N a n o f l a g e l l a t e s , u n i d e n t i f i e d M i c r o f Microf P N a v i c u l o i d s Navicu Navicu Baci P N i t z s c h i a p a c i f i c a Nitpac Nitpac Baci P N i t z s c h i a spp. N i t z s c N i t z s c Bac i P N o c t i l u c a s c i n t i l l a n s Nocsci Nocsci Dino H Ochromonas sp. Ochrom Ochrom Chry P O d o n t e l l a a u r i t a Odoaur Odoaur Bac i P O d o n t e l l a l o n g i c r u r i s B i d l o n B i d l o n Bac i P Oxyphysis oxytoxoides Oxyoxy Oxyoxy Dino H P a r a l i a s u l c a t a P a r s u l P a r s u l Bac i P Pennate diatoms, u n i d e n t i f i e d Pennat Pennat Bac i P Pleurosigma/Gyrosigma spp. Pleuro Pleuro Bac i P P o l y k r i k o s k o f o i d i i Polkof Polkof Dino H Prorocentrum g r a c i l e Progrc Progrc Dino P Protogonyaulax tamarensis Protam Protam Dino p Protogonyaulax c a t e n e l l a Procat Procat Dino P P r o t o p e r i d i n i u m achromaticum Proach Protop Dino H P r o t o p e r i d i n i u m acutum Proacu Protop Dino H P r o t o p e r i d i n i u m a n g u s t i c o l l i s Proang Protop Dino H P r o t o p e r i d i n i u m a v e l l a n a Proave Protop Dino H P r o t o p e r i d i n i u m bipes Probip Protop Dino H P r o t o p e r i d i n i u m b r e v i p e s Probre Protop Dino H P r o t o p e r i d i n i u m cerasus Procer Protop Dino H P r o t o p e r i d i n i u m c l a u d i c a n s P r o c l a Protop Dino H P r o t o p e r i d i n i u m c o n i c o i d e s Procnd Protop Dino H P r o t o p e r i d i n i u m conicum Procnm Protop Dino H P r o t o p e r i d i n i u m c r a s s i p e s Procra Protop Dino •H P r o t o p e r i d i n i u m d e f i c i e n s Prodef Protop Dino H P r o t o p e r i d i n i u m d e n t i c u l a t u m Proden Protop Dino H P r o t o p e r i d i n i u m depressum Prodep Protop Dino H P r o t o p e r i d i n i u m d i v a r i c a t u m Prodvc Protop Dino H P r o t o p e r i d i n i u m excentricum Proexc Protop Dino H P r o t o p e r i d i n i u m furcatum Pr o f u r Protop Dino H P r o t o p e r i d i n i u m g r a n i i Progrn Protop Dino •H P r o t o p e r i d i n i u m l e o n i s P roleo Protop Dino H P r o t o p e r i d i n i u m monovelum Promon Protop Dino H P r o t o p e r i d i n i u m oceanicum Prooce Protop Dino H P r o t o p e r i d i n i u m p a l l i d u m Propal Protop Dino H P r o t o p e r i d i n i u m p e l l u c i d u m Propel Protop Dino H P r o t o p e r i d i n i u m pentagonum Propen Protop Dino H P r o t o p e r i d i n i u m pyriforme Propyr Protop Dino H 267 TABLE 23. Organisms observed i n the NSG and MC. Organisms O r i g i n a l Used C l a s s PS/ Observed Code Code Het P r o t o p e r i d i n i u m rhomboidalis Prorho Protop Dino H P r o t o p e r i d i n i u m spp. Protop Protop Dino H P r o t o p e r i d i n i u m subcurvipes Prosbc Protop Dino H P r o t o p e r i d i n i u m subinerme Prosub Protop Dino H P r o t o p e r i d i n i u m thorianum Protho Protop Dino H Pyramimonas spp. Pyrami Pyrami Pras P R h i z o s o l e n i a d e l i c a t u l a R h i d e l R h i d e l Bac i P R h i z o s o l e n i a f r a g i l i s s i m a R h i f r a R h i f r a Baci P R h i z o s o l e n i a s e t i g e r a Rhiset Rhiset Baci P R h i z o s o l e n i a sp. Rhizos Rhizos Bac i P R h i z o s o l e n i a s t o l t e r f o t h i i R h i s t o R h i s t o Bac i P S c r i p p s i e l l a t r o c h o i d e a S c r i p p S c r i p p Dino P Skeletonema costatum Skecos Skecos Bac i P Stephanopyxis ni p p o n i c a S t e n i p S t e n i p Bac i P Stephanopyxis t u r r i s S t e t u r S t e t u r Bac i P T e t r a s e l m i s spp. Te t r a s T e t r a s Pras P Thalassionema n i t z s c h i o i d e s Thanit Thanit Bac i P T h a l a s s i o s i r a a e s t i v a l i s Thaaes Thaaes Bac i P T h a l a s s i o s i r a a n g s t i i Thaags Thaags Bac i P T h a l a s s i o s i r a a n g u s t e - l i n e a t a Thaang Thaang Bac i P T h a l a s s i o s i r a e c c e n t r i c a Thaecc Thaecc Baci P T h a l a s s i o s i r a n o r d e n s k i o e l d i i Thanor Thanor Bac i P T h a l a s s i o s i r a r o t u l a Tharot Tharot Bac i P T h a l a s s i o s i r a spp. Thalas Thalas Baci P T h a l a s s i o t h r i x f r a u e n f e l d i i T hafra Thafra Bac i P T r o p i d o n e i s l e p i d o p t e r a T r o l e p T r o l e p Bac i P Unknown 26 Unkn26 Amph i d Dino H Unknown 28 Unkn28 Unknow -Unknown 37 Unkn37 Amph i d Dino H Unknown 48 Unkn48 Amph i d Dino H Unknown 49 Unkn49 Amph i d Dino H Unknown 56 Unkn56 Gyrodi Dino H Unknown 57 Unkn57 Gyrodi Dino H Unknown 61 Unkn6l Amph i d Dino H Unknown 62 Unkn62 Amph i d Dino H Unknown 71 Unkn71 Gyrodi Dino H Unknown 72 Unkn72 Amphid Dino H Unknown 73 Unkn73 Amphid Dino H Unknown 77 Unkn77 Gymnod Dino P Unknown 81 Unkn8l Glenod Dino P Z o o f l a g e l l a t e s Z o o f l a Z o o f l a — H 268 APPENDIX 2. SPECIES OF SPECIAL INTEREST Alexandrium o s t e n f e l d i i T h i s d i n o f l a g e l l a t e was g e n e r a l l y most abundant i n northern waters of the NSG. There were i s o l a t e d patches of 5 c e l l S ' L " 1 along Transect 4 in March ( F i g . 48a) and A p r i l ( F i g . 48b). By June ( F i g . 48c) they were found throughout the S t r a i t (max = 20 cells«L" 1) with c o n c e n t r a t i o n s i n the northwest near the t i d a l j e t , i n the southwest o f f Cape Lazo, and i n the southeast o f f Powell R i v e r . In August ( F i g . 48d) A. o s t e n f e l d i i e x h i b i t e d maximum c o n c e n t r a t i o n s of 400 c e l l S ' L " 1 i n the northwest. By September ( F i g . 48e) c o n c e n t r a t i o n s were g r e a t e s t of a l l times sampled, with a maximum of 2500 c e l l S ' L " 1 at Stn 5c near S u t i l Channel. T h i s area showed maximal s t r a t i f i c a t i o n due to a p o s s i b l e s a l i n i t y i n t r u s i o n which appears to be r e f l e c t e d i n the a r e a l p a t t e r n of t h i s d i n o f l a g e l l a t e . Chaetoceros convolutus T h i s diatom i s armoured with spiny setae which can k i l l caged f i s h by t e a r i n g of the g i l l s . I t i s a l s o known to be a winter blooming s p e c i e s ; however, d u r i n g the course of t h i s study maximal c o n c e n t r a t i o n s were found i n August (2000 c e l l S ' L " 1 ; F i g . 49d) on the s t r a t i f i e d east s i d e o f f Malaspina P e n i n s u l a . They a l s o favoured t h i s area d u r i n g A p r i l ( F i g . 49b) though c o n c e n t r a t i o n s were an order of magnitude lower. In March ( F i g . 49a) the northeast and southeast e x h i b i t e d e l e v a t e d p o p u l a t i o n s . In June ( F i g . 49c) and September ( F i g . 49e) 269 Ch. convolutus was centered i n m i d - S t r a i t , the former with a sparse p o p u l a t i o n (200 c e l l s - L " 1 ) while the l a t t e r c o n t a i n e d up to 1400 c e l l s - L " 1 . D i c t y o c h a speculum T h i s s i l i c o f l a g e l l a t e favoured d i f f e r e n t areas of the NSG over the course of the study. In March ( F i g . 50a) and A p r i l ( F i g . 50b) numbers were low. March found g r e a t e s t c o n c e n t r a t i o n s (400 c e l l S ' L - 1 ) near the t i d a l j e t while D. speculum favoured southern c e n t r a l waters in A p r i l (500 c e l l s - L " 1 ) . Up to 6000 c e l l s - L " 1 occurred on the east s i d e i n June ( F i g . 50c) and a s i m i l a r c o n c e n t r a t i o n was evident o f f Cape Lazo i n August ( F i g . 50d). By September ( F i g . 50e) the p o p u l a t i o n was centered i n m i d - S t r a i t (2500 c e l l s - L " 1 ) . D inophysis acuminata T h i s Dinophysis s p e c i e s was only present i n s u f f i c i e n t number d u r i n g June (max = 25 c e l l s - L " 1 ) , August (max = 120 c e l l s « L " 1 ) , and September (max = 25 c e l l s - L " 1 ) . In June ( F i g . 51a) they were concentrated i n the northwest t i d a l plume. During both the August ( F i g . 51b) and September ( F i g . 51c) sampling times D. acuminata p r e f e r r e d e i t h e r the western or e a s t e r n s i d e s with a tendency towards the n o r t h . 270 Dinophysis f o r t i i In A p r i l ( F i g . 52a) there was an i s o l a t e d patch (4 cells«L" 1) of t h i s d i n o f l a g e l l a t e on the east s i d e . By June ( F i g . 52b) the patch (5 c e l l S ' L " 1 ) had moved to the western and c e n t r a l NSG. In September ( F i g . 52c) the patch was back on the e a s t e r n s i d e with 30 c e l l S ' L " 1 . D inophysis n o r v e g i c a T h i s d i n o f l a g e l l a t e reached c o n c e n t r a t i o n s of 5 c e l l S ' l r 1 i n A p r i l ( F i g . 53a), l o c a t e d i n the northwest and n o r t h e a s t . By June ( F i g . 53b) the p o p u l a t i o n had i n c r e a s e d to 70 c e l l S ' L " 1 on the west s i d e . Remaining on the west s i d e i n August ( F i g . 53c), D. n o r v e g i c a had i n c r e a s e d to 50 c e l l S ' L " 1 . September ( F i g . 53d) saw the l a r g e s t c o n c e n t r a t i o n (200 c e l l S ' L " 1 ) i n the n o r t h . Dinophysis ovum T h i s s m a l l e r Dinophysis s p e c i e s o c c u r r e d i n a patch (5 c e l l s « L _ 1 ) i n March ( F i g . 54a) near the t i d a l j e t . By June ( F i g . 54b) i t had become u b i q u i t o u s with a peak c o n c e n t r a t i o n of 100 c e l l S ' L " 1 near Cape Lazo. In August ( F i g . 54c) a background p o p u l a t i o n of 20-40 c e l l S ' L " 1 was apparent with 60 c e l l s - L " 1 on the east s i d e . 271 Dinophysis spp. Because i n d i v i d u a l s p e c i e s of t h i s genus were somewhat low and because t h i s genus i s known to be r e s p o n s i b l e f o r DSP, the four p r e v i o u s s p e c i e s were grouped and t h e i r d i s t r i b u t i o n s are presented. O v e r a l l i t i s apparent that t h i s genus p r e f e r r e d the t i d a l l y - m i x e d northern waters. In June ( F i g . 55c) and August ( F i g . 55d) Dinophysis seemed to respond p o s i t i v e l y to the t i d a l j e t whereas i n September ( F i g . 55e) the l a r g e s t c o n c e n t r a t i o n s appeared to i n t r u d e from S u t i l Channel, as mentioned p r e v i o u s l y for Alexandrium o s t e n f e l d i i . Gymnodinium sanguineum T h i s athecate d i n o f l a g e l l a t e was c o n c e n t r a t e d i n the northwest t i d a l j e t d u r i n g June (10 c e l l s - L " 1 ; F i g . 56a) and September (25 c e l l s - L " 1 ; F i g . 56b). In August ( F i g . 56c), however, i t o c c u r r e d i n r e l a t i v e l y l a r g e numbers on the east s i d e (1500 c e l l s - L " 1 ) , c o i n c i d e n t a l with s t r a t i f i e d waters. Heterosigma akashiwo T h i s raphidophyte i s of p a r t i c u l a r i n t e r e s t because of i t s known a b i l i t y to k i l l caged salmon. In A p r i l ( F i g . 57a) there were 300 c e l l s - L " 1 m i d - S t r a i t along Transect 4. By June ( F i g . 57b) H. akashiwo had become the major p h o t o s y n t h e t i c dominant with peak c o n c e n t r a t i o n s of 160,000 c e l l s - L " 1 i n the northwest t i d a l j e t . In August ( F i g . 57c) they were s t i l l abundant i n the t i d a l j e t area (5000 c e l l s - L " 1 ) whereas in 272 September ( F i g . 57d) peak c o n c e n t r a t i o n s o c c u r r e d m i d - S t r a i t (15,000 c e l l s . L - 1 ) . N o c t i l u c a s c i n t i l l a n s In A p r i l ( F i g . 58a) there appeared to be a p o s s i b l e i n t r u s i o n (200 cells«L" 1) from S u t i l Channel. In June ( F i g . 58b) a p o p u l a t i o n of 80 cells«L" 1 o c c u r r e d on the west s i d e . August ( F i g . 58c) saw maximal c o n c e n t r a t i o n s of 100 c e l l S ' L " 1 i n the northwest. There were 150 cells«L" 1 a s s o c i a t e d with the s a l i n i t y s t r a t i f i e d northern waters i n September ( F i g . 58d). Protogonyaulax c a t e n e l l a T h i s chain-forming d i n o f l a g e l l a t e i s known to cause PSP. In June ( F i g . 59a) there were 1000 c e l l s - L " 1 a s s o c i a t e d with the NW t i d a l j e t , with p o p u l a t i o n s extending down the west s i d e . In August ( F i g . 59b) peak c o n c e n t r a t i o n s (500 c e l l S ' L " 1 ) o c c u r r e d m i d - S t r a i t i n the south. By September ( F i g . 59c) c o n c e n t r a t i o n s had i n c r e a s e d once more (1000 c e l l s • L ~ 1 ) , l o c a t e d o f f Cape Lazo. Prorocentrum g r a c i l e T h i s small d i n o f l a g e l l a t e appeared to favour southern waters at a l l times sampled. In March ( F i g . 60a) and A p r i l ( F i g . 60b) i t occurred o f f Cape Lazo, r a d i a t i n g from the southwest, with peak c o n c e n t r a t i o o n s of 300 and 1400 c e l l s - L * 1 , r e s p e c t i v e l y . In June ( F i g . 60c) P. g r a c i l e was c o n c e n t r a t e d on the e a s t e r n (300 c e l l S ' L " 1 ) and western (200 c e l l s - L " 1 ) s i d e s . 273 In August ( F i g . 60d) a s i m i l a r p a t t e r n had p e r s i s t e d with 6000 c e l l s - L " 1 on the east s i d e and 12,000 c e l l s - L " 1 i n the southwest. By September ( F i g . 60e) the peak c o n c e n t r a t i o n i n the southeast was reduced to 60 c e l l s - L " 1 . Protogonyaulax tamarensis L i k e P. g r a c i l e t h i s d i n o f l a g e l l a t e p r e f e r r e d southern waters. In March ( F i g . 61a) and A p r i l ( F i g . 61b) peak c o n c e n t r a t i o n s were 200 and 300 c e l l s - L " 1 , r e s p e c t i v e l y , o c c u r r i n g i n the southern mid-NSG. In June ( F i g . 61c) the p o p u l a t i o n reached 4000 c e l l s - L " 1 o f f Cape Lazo, which i n c r e a s e d to 5000 c e l l s - L " 1 i n August ( F i g . 61d). By September ( F i g . 6le) P. tamarensis was s t i l l c o n c e n t r a t e d i n the southwest but had decreased to 200 c e l l s - L " 1 . F i g u r e 48. Alexandrium a.March b . A p r i l c . J u n e o s t e n f e l d i i ( c e l l s / L ) d.August a .September F i g u r e 49. Chaetoceros c o n v o l u t u s ( c e l l s / L ) a.March b . A p r i l c . J u n e d.Augu3t e . September ro F i g u r e 50. D i c t y o c h a speculum ( c e l l s / L ) a.March b . A p r i l c . J u n e d .August e . September F i g u r e 51. D i n o p h y s i s acuminata ( c e l l s / L ) F i g u r e 52. D i n o p h y s i s f o r t i i ( c e l l s / L ) a . J u n e b .August c .September a . A p r i l b . June C .Sep tember ro F i g u r e 53. D i n o p h y s i s n o r v e g i c a ( c e l l s / L ) a.A p r i l b .June c .Augus t d .September ro oo F i g u r e 54. D i n o p h y s i s ovum ( c e l l s / L ) a.March b .June c .Augus t d .September F i g u r e 55. D i n o p h y s i s spp. ( c e l l s / L ) a.March b . A p r i l c . J u n e d .Augus t e . September F i g u r e 57. Heterosigma akashiwo ( c e l l s / L ) a . A p r i l b . June c .Augu s t d .September F i g u r e 58. N o c t i l u c a s c i n t i l l a n s ( c e l l s / L ) a . A p r i l b . June c .Augus t d .September oo co 284 F i g u r e BO. Prorocentrum g r a c i l e ( c e l l s / L ) a.March b.Apr11 c . J u n e d .Augus t e . September F i g u r e 61. Protogonyaulax t a m a r e n s i s ( c e l l s / L ) a.March b . A p r i l c . J u n e d .Augus t e .September APPENDIX 3 - Unknown flagellates 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0053243/manifest

Comment

Related Items