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Influence of hydrographic properties in Saanich Inlet on ontogenetic migration and retainment of the… French, Shirley E. 1988

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INFLUENCE OF HYDROGRAPHIC PROPERTIES IN SAANICH ON ONTOGENETIC MIGRATION AND RETAINMENT OF THE CALANOID COPEPOD NEOCALANUS PLUMCHRUS by SHIRLEY E. FRENCH B.Sc, Brandon University, 1984 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department of Zoology) We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA January 1988 © Shirley E. French, 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 The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 . DE-6(3/81) i i A B S T R A C T D u r i n g some y e a r s N e o c a l a n u s p l u m c h r u s o v e r w i n t e r s i n S a a n i c h I n l e t w h i l e i n o t h e r y e a r s t h e y a r e a b s e n t f r o m t h e f j o r d ( H a r r i s o n e t a l . , 1 9 8 3 ) . T h e c a u s e o f t h i s v a r i a t i o n i s n o t known b u t t h e a n n u a l d e v e l o p m e n t o f a n o x i c c o n d i t i o n s f o l l o w e d b y an i n t r u s i o n o f d e n s e , o x y g e n a t e d w a t e r , was s u s p e c t e d t o i n f l u e n c e t h e i r d i s t r i b u t i o n a n d a b u n d a n c e . V e r t i c a l a n d h o r i z o n t a l h a u l s a m p l e s c o l l e c t e d f r o m S a a n i c h I n l e t i n d i c a t e d t h e o v e r w i n t e r i n g p o p u l a t i o n i n 1985 ( S e p t e m b e r 1985 t o M a r c h 1986) was s p a r s e ; i n S e p t e m b e r 1986 t h e p o p u l a t i o n o f N . p l u m c h r u s was c o m p a r a b l y l o w . I n t h e s p r i n g a n d s u m m e r , N . p l u m c h r u s i s i n t r o d u c e d f r o m t h e S t r a i t o f G e o r g i a a n d J u a n de F u c a S t r a i t , a n d i n some y e a r s may a r i s e f r o m r e p r o d u c t i o n w i t h i n t h e i n l e t . So few a d u l t s w e r e c o l l e c t e d a t t h e t h r e e s t a t i o n s i n S a a n i c h I n l e t i n J a n u a r y - M a r c h 1986 (<0.20 nr 3 ) t h a t t h e i r p o t e n t i a l c o n t r i b u t i o n t o t h e s p r i n g p o p u l a t i o n was c o n s i d e r e d n e g l i g i b l e . D e c l i n e i n t h e o v e r w i n t e r i n g p o p u l a t i o n i n S e p t e m b e r 1985 a n d 1986 a p p e a r s t o be c o r r e l a t e d w i t h t h e o c c u r r e n c e o f a n e x t e n s i v e d e e p w a t e r r e n e w a l . T h e d i s t r i b u t i o n o f N . p l u m c h r u s d u r i n g e a r l y s t a g e s o f t h e i r d e e p w a t e r m i g r a t i o n ( J u n e t o A u g u s t ) , i s i n f l u e n c e d b y t h e l o w o x y g e n c o n c e n t r a t i o n s i n t h e b o t t o m o f t h e i n l e t ( i . e . 0 . 1 0 - 0 . 3 0 mL L " 1 ) . D u r i n g t h e r e n e w a l , c o p e p o d s o c c u r r e d a b o v e t h e o x y g e n m i n i m u m (75 m) p o s s i b l y d u e t o t h e i r d i s p l a c e m e n t o r t h e i r a v o i d a n c e o f t h e l o w o x y g e n z o n e . S u b s e q u e n t l y , t h e y w e r e e x p o s e d t o t i d a l t r a n s p o r t o u t o f t h e i n l e t a n d p e r h a p s t o i n c r e a s e d p r e d a t i o n . On t w o o c c a s i o n s i n w h i c h N . p l u m c h r u s was p r e s e n t d u r i n g the winter i n Saanich I n l e t (1969 & 1974), a high volume of dense water i n t r u d e d , d i s r u p t i n g the copepod l a y e r d u r i n g the mixing of the two water masses. Even though a g r e a t e r volume of water l e f t the i n l e t some of the copepods c o u l d have remained in the water, below s i l l depth. Neocalanus plumchrus s u c c e s s f u l l y overwinters and reproduces i n Sec h e l t I n l e t which i s well-oxygenated but has a very shallow s i l l (15 m) that ' l o c k s ' the copepods i n t o the i n l e t . The f i f t h copepodite stages a l s o occupy deeper depths i n S e c h e l t I n l e t than i n Saanich I n l e t , even though the bottom depths are comparable. In low oxygen t o l e r a n c e experiments many f a c t o r s such as the p e r i o d of c a p t i v i t y , and the re g i o n of o r i g i n ( i . e . Saanich I n l e t versus the S t r a i t of Georgia) caused v a r i a b l e r e s u l t s . Although the minimum oxygen l e v e l t o l e r a b l e d u r i n g t h e i r m i g r a t i o n c o u l d not be determined, N. plumchrus t o l e r a t e d l e v e l s as low as 0.56 mL L ~ 1 (12% m o r t a l i t y ) . Sediment t r a p samples i n d i c a t e that a massive d i e o f f c o u l d not account f o r the l o s s of N. plumchrus from Saanich I n l e t . iv TABLE OF CONTENTS ABSTRACT i i LIST OF TABLES v i LIST OF FIGURES ix ACKNOWLEDGEMENTS . x i i i 1 . INTRODUCTION 1 1.1. L i f e H i s t o r y of Neocalanus plumchrus 4 2 . THE STUDY AREAS 7 2.1 P h y s i c a l C h a r a c t e r i s t i c s 7 2.1.1 Saanich I n l e t 7 2.1.2. S t r a i t of Georgia 10 2.1.3 S e c h e l t I n l e t 12 2.2. S t a t i o n S e l e c t i o n 13 3. MATERIALS AND METHODS 16 3.1. Hydrographic Data 16 3.2. Zooplankton Sampling 17 3.3. Treatment of Net Haul Samples 20 3.4. C o l l e c t i o n and Maintenance of L i v e Copepods ....... 21 3.5. Experimental Procedures 23 3.6. Sediment Trap Samples 25 3.7. S t a t i s t i c a l Methods 26 4. RESULTS 28 4.1. A n a l y s i s of the P h y s i c a l Data 28 4.1.1. Saanich I n l e t 28 4.1.2. S t a t i o n G1748 & G1545 32 4.1.3. S e c h e l t I n l e t 34 4.2 . A n a l y s i s of Ne t ,Hau l Samples 35 4 . 2 . 1 . S t r a i t of Georg i a V e r t i c a l Hau l s 36 4 . 2 . 2 . S a t e l l i t e Channel 38 4 . 2 . 3 . Saan i ch I n l e t 39 4 . 2 . 4 . S e c h e l t I n l e t 45 4 . 3 . A n a l y s i s of Expe r imen ta l Data 46 4 . 3 . 1 . O b s e r v a t i o n s of Fed and S t a r ved Copepods 46 4 . 3 . 2 . Oxygen T o l e r a n c e T e s t s 47 4 .4 . Sediment T r a p Samples 49 5. DISCUSSION 52 5 .1 . P h y s i c a l i n f l u e n c e s on the Neocalanus plumchrus p o p u l a t i o n i n Saan i ch I n l e t 52 5.2. A l t e r n a t i v e Causes f o r the D e c l i n e of N. plumchrus i n Saan ich 63 6. CONCLUSIONS 71 R e f e r e n c e s 169 Appendix A 1 7 4 v i LIST OF TABLES Table 1. S t a t i o n c o o r d i n a t e s and maximum depths 75 Table 2. Hydrographic and b i o l o g i c a l s t a t i o n s sampled i n 1985 76 Table 3. Hydrographic and b i o l o g i c a l s t a t i o n s sampled i n 1986 77 Table 4. Flowmeter measurements with and without the mSCOR net 78 Table 5. Low oxygen t o l e r a n c e experiments on CVs 79 Table 6. D i s s o l v e d oxygen c o n c e n t r a t i o n s at Saa9 i n 1985. . 81 Table 7. D i s s o l v e d oxygen c o n c e n t r a t i o n s at Saa9 i n 1986. . 81 Table 8. Hydrographic data c o l l e c t e d August 5, 1986, at s t a t i o n Saa3 81 Table 9. D i s s o l v e d oxygen c o n c e n t r a t i o n s at Saa0.8 i n 1985. 82 Table 10. D i s s o l v e d oxygen c o n c e n t r a t i o n s at Saa0.8 i n 1986 82 Table 11. D i s s o l v e d oxygen c o n c e n t r a t i o n s at G1545 and G1748 83 Table 12. D i s s o l v e d oxygen c o n c e n t r a t i o n s at G1545 i n 1986. 83 Table 13. V e r t i c a l plankton hauls c o l l e c t e d i n 1985 84 Table 14. V a r i a t i o n between r e p l i c a t e v e r t i c a l haul samples 85 Table 15. V e r t i c a l plankton hauls c o l l e c t e d i n 1986 86 Table 16. H o r i z o n t a l plankton hauls c o l l e c t e d at s t a t i o n v i i Saa3 in 1985. 90 Tab le 17. H o r i z o n t a l and o b l i q u e p l ank ton hau l s c o l l e c t e d in 1986 91 Tab le 18. ANOVA-Stra i t of Georg ia c o u n t s , f a l l ve r sus s p r i n g and summer 93 Tab le 19. ANOVA-St ra i t of Georg ia coun t s , f a l l 1985 ver sus f a l l 1986 95 T a b l e 20. ANOVA-Saanich I n l e t counts f o r Saa3, May, J u l y , and August , 1985 and 1986 96 T a b l e 21. ANOVA-Saanich I n l e t counts from A p r i l through August 1986 98 Tab le 22. ANOVA-Saanich I n l e t counts f o r Saa9 and Saa0.8, A p r i l through August 1986 100 T a b l e 23. ANOVA-Saanich I n l e t counts f o r Saa3 and Saa0.8, A p r i l through August 1986 102 Tab le 24. ANOVA-Saanich I n l e t counts f o r Saa9 and Saa3, A p r i l through August 1986 104 Tab le 25. ANOVA-Saanich I n l e t counts at Saa9 ver sus S t r a i t of Georg ia c o u n t s , 1986 105 T a b l e 26. ANOVA-Saanich I n l e t counts at Saa0.8 ve r su s S t r a i t of Georg ia c o u n t s , 1986 107 T a b l e 27. ANOVA-Saanich I n l e t counts at Saa9, h o r i z o n t a l r e p l i c a t e s taken in J u l y 1986 109 Tab le 28. Copepod f a e c a l p e l l e t p r o d u c t i o n over a 12 hour p e r i o d . 110 Tab le 29. Buoyancy of CVs f o l l o w i n g t h e i r death i n exper iments 8 and 9 110 T a b l e 30. C a l c u l a t e d volume of water f i l t e r e d through the v i i i mSCOR net 111 Table 31. C o n c e n t r a t i o n s of N. plumchrus and d i s s o l v e d oxygen from c e n t r a l Saanich I n l e t , 1969 1 1 1 Table 32. D i s s o l v e d oxygen c o n c e n t r a t i o n s measured i n Saanich I n l e t i n 1969 112 Table 33. D i s s o l v e d oxygen c o n c e n t r a t i o n s measured i n Saanich I n l e t i n 1974 113 Table 34. G e l a t i n o u s zooplankton c o l l e c t e d i n September 1985 114 ix LIST OF FIGURES F i g u r e 1. The study area 115 F i g u r e 2. L i f e h i s t o r y stages c h a r a c t e r i s t i c of Neocalanus plumchrus 116 F i g u r e 3. S e c h e l t I n l e t and S t r a i t of Georgia s t a t i o n s . ...117 F i g u r e 4. Saanich I n l e t s t a t i o n s ...118 F i g u r e 5. The m o d i f i e d SCOR net 119 F i g u r e 6. Bathykymograph r e s u l t s . 120 F i g u r e 7. Apparatus f o r low-oxygen t o l e r a n c e experiments. .120 F i g u r e 8. A r e g r e s s i o n of the l o g mean versus the l o g v a r i a n c e 121 F i g u r e 9. S a l i n i t y d i s t r i b u t i o n f o r s t a t i o n Saa9 i n 1985. .122 F i g u r e 10. Temperature d i s t r i b u t i o n f o r s t a t i o n Saa9 i n 1985 123 F i g u r e 11. D e n s i t y d i s t r i b u t i o n f o r s t a t i o n Saa9 i n 1985. .124 F i g u r e 12. D i s s o l v e d oxygen d i s t r i b u t i o n f o r s t a t i o n Saa9 i n 1985 125 F i g u r e 13. S a l i n i t y d i s t r i b u t i o n f o r s t a t i o n Saa9 i n 1986. 126 F i g u r e 14. Temperature d i s t r i b u t i o n f o r s t a t i o n Saa9 i n 1986 127 F i g u r e 15. D e n s i t y d i s t r i b u t i o n f o r s t a t i o n Saa9 i n 1986. .128 F i g u r e 16. D i s s o l v e d oxygen d i s t r i b u t i o n f o r s t a t i o n Saa9 i n 1986 129 F i g u r e 17. Copepod c o n c e n t r a t i o n s and d i s s o l v e d oxygen l e v e l s at s t a t i o n Saa3, August 1985 130 F i g u r e 18. Copepod c o n c e n t r a t i o n s and d i s s o l v e d oxygen X l e v e l s at s t a t i o n Saa3, August 1986 131 Fi g u r e 19. S a l i n i t y d i s t r i b u t i o n f o r s t a t i o n Saa0.8 i n 1985. 132 Fi g u r e 20. Temperature d i s t r i b u t i o n f o r s t a t i o n Saa0.8 i n 1985 133 F i g u r e 21. De n s i t y d i s t r i b u t i o n f o r s t a t i o n Saa0.8 i n 1985. 134 F i g u r e 22. D i s s o l v e d oxygen d i s t r i b u t i o n f o r s t a t i o n Saa0.8 i n 1985 135 F i g u r e 23. S a l i n i t y d i s t r i b u t i o n f o r s t a t i o n Saa0.8 i n 1 986 136 F i g u r e 24. Temperature d i s t r i b u t i o n f o r s t a t i o n Saa0.8 i n 1986 137 F i g u r e 25. Densi t y d i s t r i b u t i o n f o r s t a t i o n Saa0.8 i n 1986. 138 F i g u r e 26. D i s s o l v e d oxygen d i s t r i b u t i o n f o r s t a t i o n Saa0.8 in 1986 139 F i g u r e 27. S a l i n i t y d i s t r i b u t i o n f o r s t a t i o n s G1545 and G1748 i n 1985 140 F i g u r e 28. Temperature d i s t r i b u t i o n f o r s t a t i o n s G1545 and G1748 i n 1985 141 F i g u r e 29. De n s i t y d i s t r i b u t i o n f o r s t a t i o n s G1545 and G1748 i n 1985 142 Fi g u r e 30. D i s s o l v e d oxygen d i s t r i b u t i o n f o r s t a t i o n s G1545 and G1748 i n 1985 143 F i g u r e 31. S a l i n i t y d i s t r i b u t i o n f o r s t a t i o n G1545 i n 1986. 144 F i g u r e 32. Temperature d i s t r i b u t i o n f o r s t a t i o n G1545 i n 1986 145 F i g u r e 33. De n s i t y d i s t r i b u t i o n f o r s t a t i o n G1545 i n 1986. 146 F i g u r e 34. D i s s o l v e d oxygen d i s t r i b u t i o n f o r s t a t i o n G1545 in 1986 147 F i g u r e 35. Hydrographic parameters c o l l e c t e d at s t a t i o n Sc1, November 1985 148 F i g u r e 36. Hydrographic parameters c o l l e c t e d at s t a t i o n Sc1 , February 1 986 1 49 F i g u r e 37. Hydrographic parameters c o l l e c t e d at s t a t i o n Sc2, August 1986 150 F i g u r e 38. Hydrographic parameters c o l l e c t e d at s t a t i o n Sc2a, August 1986 151 F i g u r e 39. V e r t i c a l d i s t r i b u t i o n of Neocalanus plumchrus at s t a t i o n s G1545 and G1748. .. . 152 F i g u r e 40. T o t a l copepod c o n c e n t r a t i o n s c o l l e c t e d i n the S t r a i t of Georgia i n 1985 and 1986 1 53 F i g u r e 41. T o t a l copepod c o n c e n t r a t i o n s c o l l e c t e d i n Saanich I n l e t and S a t e l l i t e Channel i n 1985 and 1986. ..154 F i g u r e 42. V e r t i c a l d i s t r i b u t i o n of Neocalanus plumchrus i n S a t e l l i t e Channel 155 F i g u r e 43. V e r t i c a l d i s t r i b u t i o n of N. plumchrus at s t a t i o n Saa3, Saanich I n l e t 156 F i g u r e 44. V e r t i c a l d i s t r i b u t i o n of N. plumchrus at s t a t i o n Saa0.8 157 F i g u r e 45. V e r t i c a l d i s t r i b u t i o n of N. plumchrus at s t a t i o n Saa9. 158 F i g u r e 46. Copepod c o n c e n t r a t i o n s and d i s s o l v e d oxygen l e v e l s at s t a t i o n Saa0.8, June 1986 159 x i i F i g u r e 47. Copepod c o n c e n t r a t i o n s and d i s s o l v e d oxygen l e v e l s at s t a t i o n Saa9, J u l y 1986 160 F i g u r e 48. V e r t i c a l d i s t r i b u t i o n of N. plumchrus at s t a t i o n Sc1, S e c h e l t I n l e t * 161 F i g u r e 49. V e r t i c a l d i s t r i b u t i o n of N. plumchrus at s t a t i o n s Sc2 and Sc2a 162 F i g u r e 50. M o r t a l i t y of s t a r v e d versus fed copepods 163 F i g u r e 51. Percent m o r t a l i t y of CVs exposed to d i f f e r e n t oxygen c o n c e n t r a t i o n s 164 F i g u r e 52. C a p t i v i t y p e r i o d and percent m o r t a l i t y of CVs s u b j e c t e d to low oxygen t o l e r a n c e t e s t s 165 F i g u r e 53. Expected r e s u l t s of low oxygen t o l e r a n c e experiments 166 F i g u r e 54. The hypothesized d i s t r i b u t i o n of N. plumchrus p r i o r t o , and d u r i n g the deep water renewal i n 1985. ...167 F i g u r e 55. Hydrographic s t a t i o n s and the zooplankton haul s t a t i o n sampled i n 1969 and 1974 168 x i i i ACKNOWLEGDEMENTS I would l i k e to extend thanks to the c a p t a i n and crew of the C.S.S. Vector f o r t h e i r a s s i s t a n c e and c o o p e r a t i o n d u r i n g sampling. I would a l s o l i k e to express my a p p r e c i a t i o n to those people who p a r t i c i p a t e d i n the c o l l e c t i o n of hydrographic and b i o l o g i c a l data, e s p e c i a l l y to Dave Tesch, Nancy B u t l e r , Hugh McLean and Tony Noble who a s s i s t e d i n the c o l l e c t i o n of zooplankton. I am g r a t e f u l to Dr. A.G. Lewis f o r h i s s u p e r v i s i o n throughout the course of t h i s study. He provided v a l u a b l e a d v i c e , f i n a n c i a l support, and encouragement, and d e d i c a t e d h i s time to e d i t i n g my t h e s i s . Dr. F.J.R. T a y l o r and John F u l t o n were h e l p f u l i n the development of t h i s p r o j e c t and o f f e r e d v a l u a b l e c r i t i c i s m on the f i n a l manuscript. Dr. W.E. N e i l l was a v a i l a b l e on many occa s i o n s to d i s c u s s my t h e s i s and p r o v i d e p e r c e p t i v e input and a d v i c e r e g a r d i n g v a r i o u s aspects of t h i s study. I would a l s o l i k e to thank Dr. W.E. N e i l l f o r reading the f i n a l d r a f t and p r o v i d i n g h e l p f u l c r i t i c i s m . Many thanks to A l i s t a i r B l a c h f o r d f o r h i s i n s t r u c t i o n s on the unix o p e r a t i n g system and to Rowan Haigh f o r h i s e n l i g h t e n i n g c o n t r i b u t i o n s to the r e s o l u t i o n of my computing problems. I would a l s o l i k e to express my a p p r e c i a t i o n t o Judy Acreman and E l a i n e Simons f o r p r o v i d i n g h e l p f u l input on c u l t u r i n g phytoplankton. The zooplankton samples analysed by Heather Dovey f o r ' j e l l i e s ' a l s o proved to be h e l p f u l to t h i s study. A very s p e c i a l thanks to Tony Noble with whom I d i s c u s s e d xiv my work and received valuable input at a l l stages of my thesis. 1 1. INTRODUCTION The oxygen minimum i n the e a s t e r n P a c i f i c Ocean from c e n t r a l Peru to C a l i f o r n i a , has been shown to have a major i n f l u e n c e on the d i s t r i b u t i o n of zooplankton (Longhurst, 1967; J u d k i n s , 1980; A l l d r e d g e et a l . , 1984). Oxygen c o n c e n t r a t i o n s of 0.1 to 0.2 mL L" 1 a c t as a b a r r i e r to the m i g r a t i o n of many s p e c i e s beyond depths of 80 to 200 m i n the more southern l a t i t u d e s (15°S to 26°N; Longhurst, 1967; Judki n s , 1980 ). A l l d r e d g e et a l . (1984) found dense aggregations of the copepod Calanus p a c i f i c u s c a l i f o r n i c u s at or j u s t above 450 meters where oxygen c o n c e n t r a t i o n s of 0.2 mL L" 1 e x i s t e d i n the Santa Barbara B a s i n , C a l i f o r n i a . In the higher l a t i t u d e s (50°N) at ocean s t a t i o n 'P', the oxygen minimum i s found at deeper depths (> 600 m; C.B. M i l l e r , p e r s . comm.). In c o a s t a l r e g i ons low oxygen c o n d i t i o n s occur i n f j o r d s which have a weak c i r c u l a t i o n and a s i l l r e s t r i c t i n g the exchange of water. Saanich I n l e t , s i t u a t e d on the southeast s i d e of Vancouver I s l a n d , B r i t i s h Columbia, c h a r a c t e r i s t i c a l l y develops anoxic bottom c o n d i t i o n s . The occurrence of these oxygen-poor waters appears to i n f l u e n c e the d i s t r i b u t i o n of the r e s i d e n t zooplankton and benthos ( F i s h , 1968; Hoos, 1970; Devol, 1981; Mackie and M i l l s , 1983; Burd & B r i n k h u r s t , 1984). Of p a r t i c u l a r i n t e r e s t i s the e f f e c t of the anoxic c o n d i t i o n s on the c a l a n o i d copepod Neocalanus plumchrus. Upwelling o f f the west coast p r o v i d e s dense water to reoxygenate the bottom waters of Saanich I n l e t between l a t e August and December of each year. Hence, the e f f e c t of the deep water renewal on the d i s t r i b u t i o n and abundance of t h i s s p e c i e s , i s a l s o of i n t e r e s t . 2 N. plumchrus i s an important component of the zooplankton community i n terms of abundance and biomass i n the S t r a i t of Georgia (LeBrasseur et a l . , 1969; Gardner, 1977; Mackie, 1985). During the s p r i n g and summer, when the copepodites are found i n the top 80 or 100 m of the water column, they can be t r a n s p o r t e d southwest and i n t o Saanich I n l e t (Black, 1984). The summer p o p u l a t i o n i n Saanich I n l e t may t h e r e f o r e c o n s i s t of copepods in t r o d u c e d from the S t r a i t of Georgia, Juan de Fuca S t r a i t and perhaps from r e p r o d u c t i o n of N. plumchrus i n Saanich I n l e t . The occurrence of an o v e r w i n t e r i n g p o p u l a t i o n i s e s s e n t i a l f o r the s u c c e s s f u l r e p r o d u c t i o n of t h i s s p e c i e s s i n c e they reproduce at depth f o l l o w i n g the o v e r w i n t e r i n g p e r i o d ( F u l t o n , 1973). H a r r i s o n et a l . (1983), however, s t a t e d that there was a lack of an o v e r w i n t e r i n g p o p u l a t i o n i n Saanich I n l e t as a r e s u l t of the depth d i f f e r e n c e between the i n l e t and the S t r a i t of Ge o r g i a . In c o n t r a s t , Hoos (1970) and Cowen (1982) had repo r t e d the presence of N. plumchrus, i n f a i r l y h igh numbers duri n g the winter i n 1969 and 1974. In Saanich I n l e t , the documentation on the abundance and d i s t r i b u t i o n of N. plumchrus i n r e l a t i o n to the oxygen regime i s incomplete. The purpose of t h i s study was to determine i f t h i s s p e c i e s can s u c c e s s f u l l y overwinter and give r i s e to subsequent ge n e r a t i o n s w i t h i n the i n l e t . I t i s proposed that the p h y s i c a l and chemical c h a r a c t e r i s t i c s of the f j o r d may hinder N. plumchrus from o v e r w i n t e r i n g and p r o v i d i n g a r e s i d e n t p o p u l a t i o n i n Saanich I n l e t d u r i n g some ye a r s . The p o p u l a t i o n i n Saanich I n l e t was sampled from e a r l y summer i n 1985 to- the f a l l of 1986 i n c o n j u n c t i o n with 3 hydrographic data. The hydrographic parameters c o u l d p o t e n t i a l l y i n f l u e n c e the d i s t r i b u t i o n and abundance of CVs and a d u l t s s i n c e these stages are found at deep depths f o l l o w i n g t h e i r m i g r a t i o n and t h e r e f o r e come i n t o c o n t a c t with the low oxygen waters. Hence, the zooplankton samples were examined f o r these two stages as w e l l as the CIVs. A comparison was made with the S t r a i t of Georgia p o p u l a t i o n where the s p e c i e s i s known to be abundant and t h e i r l i f e h i s t o r y i s w e l l documented ( F u l t o n , 1973; Gardner, 1977). S e c h e l t I n l e t was sampled o c c a s i o n a l l y s i n c e i t i s s i m i l a r i n depth to Saanich I n l e t yet i t has a shallower s i l l (15 m) and i s well-oxygenated. In the l a b o r a t o r y , the t o l e r a n c e of t h i s s p e c i e s to low oxygen was measured i n an attempt to estimate t h e i r s u r v i v a l at v a r i o u s oxygen l e v e l s and to r e l a t e t h i s to depth of m i g r a t i o n i n Saanich I n l e t . Sediment t r a p samples c o l l e c t e d i n Saanich I n l e t were examined f o r s i g n s of d i e o f f i n N. plumchrus. 4 1.1. L i f e H i s t o r y of Neocalanus plumchrus Neocalanus plumchrus i s a s p e c i e s of c a l a n o i d copepod commonly found i n c o a s t a l waters of B r i t i s h Columbia ( f i g u r e 1). In the S t r a i t of Georgia, N. plumchrus i s one of the predominant components of the mesoplankton and i s o f t e n t r a n s p o r t e d i n t o adjacent bodies of water where i t may e s t a b l i s h r e p r o d u c t i v e p o p u l a t i o n s ( K o e l l e r , 1974; Mackie, 1985). The s p e c i e s i s an important food item f o r many p l a n k t i v o r e s due to i t s abundance and r e l a t i v e l y l a r g e s i z e (LeBrasseur et a l . , 1969; F u l t o n , 1973; Gardner, 1977). As i s t y p i c a l of c a l a n o i d s , N. plumchrus develops from the egg i n t o s i x subsequent n a u p l i a r stages (NI-NVI) and s i x copepodite stages (CI-CVI)(Gardner & Szabo, 1982; f i g u r e 2). The f i n a l stage (CVI) i s the s e x u a l l y mature a d u l t phase which i s e i t h e r male or female. The p o p u l a t i o n of N. plumchrus i n the S t r a i t of Georgia i s u n i v o l t i n e , breeding only once a year, while at l e a s t some of the oceanic p o p u l a t i o n s are b i v o l t i n e ( F u l t o n , 1973; M i l l e r et a l . , 1984). In the S t r a i t of Georgia, f e r t i l i z a t i o n occurs du r i n g the months of December through February, a f t e r the moult from CV to a d u l t ( F u l t o n , 1973). E c d y s i s , f e r t i l i z a t i o n , and egg l a y i n g takes p l a c e at o v e r w i n t e r i n g depths between 300 and 450 meters ( F u l t o n , 1973). Egg r e l e a s e commences i n e a r l y January and extends i n t o m i d - A p r i l , d e c l i n i n g as the muscle t i s s u e and l i p i d r e s e r v e s of the a d u l t females are u t i l i z e d . Of the a d u l t females c o l l e c t e d i n 1968 by F u l t o n (1973) each female produced an average of 9.5 c l u t c h e s with 56.3 eggs per c l u t c h . F o l l o w i n g the r e p r o d u c t i v e p e r i o d the females d i e at depth. Adult males decrease i n number 5 p r i o r to females so presumably they d i e soon a f t e r f e r t i l i z a t i o n occurs (Gardner, 1972; F u l t o n , 1973). As n a u p l i i develop they swim or f l o a t towards shallow depths from deep regions where the eggs were r e l e a s e d ( F u l t o n , 1973). While i n the upper 100 meters of the S t r a i t n a u p l i i may o b t a i n nourishment from t h e i r l i p i d r e s e r v e s , present i n t o the 6th n a u p l i a r stage and from phytoplankton (Lee et a l . , 1972; F u l t o n , 1973). A d u l t s reproduce below the euphotic zone so they do not reproduce i n response to the l e v e l of primary p r o d u c t i v i t y at the s u r f a c e . The p e r i o d of egg l a y i n g extends over s e v e r a l months ens u r i n g that some of the n a u p l i i are c o i n c i d e n t with the s p r i n g phytoplankton bloom ( F u l t o n , 1973; H a r r i s o n et a l . , 1983). From l a t e February t o e a r l y June n a u p l i i progress through copepodite stages CI through CIV, feed i n g p r i m a r i l y on phytoplankton ( F u l t o n , 1973; Gardner, 1977). Samples of CVs c o l l e c t e d d u r i n g dawn, midnight and dusk i n d i c a t e t hat they are not d i u r n a l m igrators (Hoos, 1970; K o e l l e r , 1974). The stage V copepodites s t a r t to appear i n the water column i n May and begin t h e i r descent to deeper depths i n June ( F u l t o n , 1973). By August and September most, i f not a l l CVs have reached o v e r w i n t e r i n g depths between 200 and 400 meters with the m a j o r i t y below 300 meters (Gardner, 1972; F u l t o n , 1973). The l a r g e l i p i d r e s e r v e b u i l t up over the summer i s thought to maintain CVs and a d u l t s while they overwinter, moult, and reproduce (Lee et a l . , 1972; H a r r i s o n et a l . , 1983). During the o v e r w i n t e r i n g p e r i o d , i t i s b e l i e v e d that they conserve energy through a r e d u c t i o n i n a c t i v i t y but the CVs may a l s o feed on 6 a l t e r n a t i v e food sources such as microzooplankton ( F r o s t et a l . , 1983; Dagg & Walser, 1987). Neocalanus plumchrus i s u b i q u i t o u s throughout the S t r a i t of Georgia but v a r i e s i n d e n s i t y a c r o s s d i f f e r e n t r e g i o n s . Young copepodite stages occupying the upper regions of the water column are c o n c e n t r a t e d i n the F r a s e r plume area towards the southern end of the S t r a i t i n e a r l y summer (Black, 1984). F i f t h stage copepodites and a d u l t s which i n h a b i t deep waters i n the f a l l and winter, are found i n g r e a t e s t numbers i n the c e n t r a l , deepest p a r t of the S t r a i t . Fewer i n d i v i d u a l s are l o c a t e d i n the northern extension of the S t r a i t of Georgia (Black, 1984). 7 2. THE STUDY AREAS In the f o l l o w i n g s e c t i o n a d e t a i l e d d e s c r i p t i o n of the p h y s i c a l c h a r a c t e r i s t i c s of the study area i s g i v e n . The i n f l u e n c e of the t i d e s , winds, and e s t u a r i n e flow and t h e i r v a r i a t i o n with season, i s d i s c u s s e d i n r e l a t i o n to the p h y s i c a l / c h e m i c a l c h a r a c t e r i s t i c s of the water. In a d d i t i o n , I e x p l a i n how these c o n d i t i o n s i n f l u e n c e d the s e l e c t i o n of s t a t i o n s i t e s i n order to study N. plumchrus i n c o n t r a s t i n g environments. 2.1 P h y s i c a l C h a r a c t e r i s t i c s 2.1.1 Saanich I n l e t Saanich I n l e t i s s i t u a t e d on the southeastern s i d e of Vancouver I s l a n d and i s connected to the S t r a i t of Georgia through a s e r i e s of passages and channels ( f i g u r e 1). The f j o r d has a maximum depth of 236 meters and i s 13 n a u t i c a l m i l e s (24 km) long (Herlinveaux, 1962). Of prime i n t e r e s t i s the c h a r a c t e r i s t i c anoxic environment which p e r s i s t s throughout much of the year. Water stagnates i n the bottom of the f j o r d as a r e s u l t of weak e s t u a r i n e c i r c u l a t i o n , t i d a l energy, winds, and the r e s t r i c t i v e nature of the 75 meter s i l l which reduces deep water exchange with adjacent waters ( S t u c c h i & Giovando, 1984). Anoxic c o n d i t i o n s develop over the winter, s p r i n g , and summer as the i n f l u x of organic d e b r i s s e t t l e s and reduces the oxygen to 8 l e v e l s below 1.0 mL L" 1 (Lu et a l . , 1986). The Goldstream r i v e r at the head of Saanich I n l e t p r o v i d e s an i n s u f f i c i e n t supply of f r e s h water f o r an e s t u a r i n e c i r c u l a t i o n (Herlinveaux, 1962). The primary sources of f r e s h water enter through the mouth of the f j o r d from the F r a s e r and the Cowichan r i v e r s . Both r i v e r s have a p e r i o d of maximum run-o f f at d i f f e r e n t times of the year, the former i n June and the l a t t e r i n December. During the summer months the winds tend to come from a s o u t h e a s t e r l y d i r e c t i o n and switch i n the winter to a more westerly o r i e n t a t i o n , i n f l u e n c i n g the movement of water i n the upper l a y e r s (Herlinveaux, 1962). In order to have replacement of the bottom waters i n Saanich I n l e t , the water e n t e r i n g through S a t e l l i t e Channel must exceed the d e n s i t y of the r e s i d e n t water. Water dense enough f o r a deep water renewal i n the i n l e t develops o f f the east coast of the P a c i f i c Ocean from A p r i l to August ( P i c k a r d & Emery, 1982). Winds blowing equatorward along the e a s t e r n P a c i f i c coast cause the water i n the Ekman l a y e r to veer to the r i g h t . These waters are r e p l a c e d by up w e l l i n g , c o o l water from 50-300 meters ( P i c k a r d & Emery, 1982). The dense, high s a l i n i t y water moves up Juan de Fuca S t r a i t and i n t o Haro S t r a i t by mid to l a t e summer ensu r i n g an annual deep water renewal i n the f j o r d (Herlinveaux, 1962). During a f l u s h i n g event the dense water i s moved from a depth of 100 meters or deeper i n Haro S t r a i t , up over the 65 meter outer s i l l of S a t e l l i t e Channel ( S t u c c h i & Giovando, 1984). The volume of water e n t e r i n g the f j o r d , and thus the extent of a renewal, v a r i e s from year to year as w e l l as the volume of water e n t e r i n g the f j o r d (Anderson and Devol, 1973; 9 IOUBC Data Report 52, 1983; Burd & B r i n k h u r s t , 1984). The t i d a l c y c l e i n f l u e n c e s the amount of water exchanged (Geyer and Cannon, 1982). Data c o l l e c t e d by the I n s t i t u t e of Ocean Science (I.O.S.) shows that d u r i n g neap t i d e a strong v e r t i c a l g r a d i e n t i s maintained with high s a l i n i t i e s i n the bottom water and low s a l i n i t i e s at the s u r f a c e ( S t u c c h i & Giovando, 1984). The v e r t i c a l g r a d i e n t i s weakened d u r i n g s p r i n g t i d e due to strong t i d a l mixing i n Haro S t r a i t , hence, lowering the d e n s i t y i n the deeper waters. The ebb flow a l s o tends to i n h i b i t the i n f l o w of water while the f l o o d t i d e causes an a c c e l e r a t i o n ( S t u c c h i & Giovando, 1984). In Saanich I n l e t , S t u c c h i and Giovando (1984) estimated the f l u s h i n g event to l a s t 8-10 days d u r i n g the three main i n f l o w p e r i o d s at the end of August, September and October of 1978. We can best understand the deep water renewal mechanism by examining a case study completed by Geyer and Cannon (1982) i n Puget Sound. They found a maximum b a r o c l i n i c flow d u r i n g neap t i d e s as a r e s u l t of low mixing. When the dense water migrated over the Puget Sound s i l l the water d e c e l e r a t e d when i t came i n t o c o n t a c t with the b a s i n water. The h i g h d e n s i t y water was moved by a g r a v i t y c u r r e n t underneath the l e s s s a l i n e water which was e n t r a i n e d above. The h y d r a u l i c jump or the entrainment of water above the high s a l i n i t y water decreased as the dense water moved f u r t h e r i n t o the sound (Geyer and Cannon, 1982). Given the d e n s i t y regime f o r a deep water renewal, concurrent t i d a l c y c l e s c o u l d be a major f a c t o r i n the extent of the exchange i n Saanich I n l e t . As v a r i o u s s t u d i e s and o b s e r v a t i o n s have i n d i c a t e d , the occurrence of the f l o o d phase 10 d u r i n g neap t i d e would favour the entrance of l a r g e r volumes of water i n t o the i n l e t . The delay, or r e d u c t i o n i n the volume of renewed water d u r i n g some years i n Saanich I n l e t (IOUBC Data Report 52, 1983; Burd & B r i n k h u r s t , 1984), c o u l d be a t t r i b u t e d to the ti m i n g of the t i d a l c y c l e but may a l s o be due to a weakened e s t u a r i n e flow i n the S t r a i t of Georgia or a reduced u p w e l l i n g event along the P a c i f i c Coast. In c o n c l u s i o n , i t i s c l e a r that the c o n d i t i o n s in t h i s i n l e t are complicated but i n gene r a l there i s a replacement of the anoxic bottom waters on an annual b a s i s . 2.1.2. S t r a i t of Georgia The S t r a i t of Georgia i s a l a r g e estuary l o c a t e d between Vancouver I s l a n d and the mainland of B r i t i s h Columbia ( f i g u r e 1). The maximum depth of the S t r a i t i s 450 meters and i t i s 119 n a u t i c a l m i l e s (220 km) in l e n g t h (Schumacher et a l . , 1978). Connections to the P a c i f i c Ocean l i e through Juan de Fuca S t r a i t to the south and Johnstone S t r a i t to the no r t h . Most of the water i n the S t r a i t of Georgia i s exchanged through the r e l a t i v e l y wide and deep southern s t r a i t s r a t h e r than Johnstone S t r a i t (LeBlond, 1983). As water moves in through the southern passage i t i s l i n k e d to the S t r a i t of Georgia through Haro S t r a i t and R o s a r i o S t r a i t . The 50 m s i l l i n Rosario S t r a i t r e s t r i c t s the i n f l o w of water to a g r e a t e r extent than the s i l l at 130 m i n Haro S t r a i t (Schumacker et a l . , 1978). These topographic f e a t u r e s c o n t r i b u t e to the co u n t e r c l o c k w i s e c i r c u l a t i o n i n the S t r a i t as do the 11 t i d e s and the f r e s h water outflow (Schumacker et a l . , 1978). On the western s i d e of the S t r a i t of Georgia the depths are g e n e r a l l y g r e a t e r than 100 m and reach maximum depths of 450 m (Schumacker et a l . , 1978). The e a s t e r n s i d e i s much shallower, with depths u s u a l l y l e s s than 50 m. In combination with the d i f f e r e n c e i n depths, the ebb t i d e along the western s i d e tends to be stronger and maintained f o r a longer p e r i o d than on the east e r n s i d e . Schumacker et a l . (1978) found the opp o s i t e to be true d u r i n g the f l o o d t i d e . The strong e s t u a r i n e flow i n the S t r a i t i s p r i m a r i l y i n f l u e n c e d by the F r a s e r River which i s estimated to c o n t r i b u t e 80% of the t o t a l f r e s h water outflow (Waldichuck, 1957). The f r e s h water plume extends to the south and c e n t r a l p a r t s of the S t r a i t and reaches a p e r i o d of maximum f r e s h e t around May or June. The f r e s h water outflow i n the summer i s thought to enhance the inf l o w of hig h s a l i n i t y water through Juan de Fuca S t r a i t even though the two-layered flow i s mixed and hence weakened as the water passes through the g u l f and San Juan I s l a n d s (LeBlond, 1983). During the winter the c o l d n e a r - s u r f a c e waters sink down to supply the deeper depths with denser water. In l a t e summer dense, high s a l i n i t y water u p w e l l i n g o f f the P a c i f i c c o a s t , g r a d u a l l y moves i n t o the deep regions of the S t r a i t of Georgia from Juan de Fuca S t r a i t (Waldichuck,1957). As a r e s u l t of t i d e s , c i r c u l a t i o n , and e s t u a r i n e flow, the deep water renewal i n the S t r a i t i s a c o n t i n u a l process throughout the year. Although i t v a r i e s i n i n t e n s i t y and i n the depth of i n t r u s i o n i t tends to keep the waters w e l l oxygenated at a l l times (LeBlond, 12 1983). 2.1.3 S e c h e l t I n l e t S e c h e l t I n l e t i s l o c a t e d on the mainland of B r i t i s h Columbia southwest of J e r v i s I n l e t ( f i g u r e 1). Narrows I n l e t and Salmon I n l e t are connected d i r e c t l y to S e c h e l t I n l e t at an angle almost p e r p e n d i c u l a r to the l e n g t h of the f j o r d . S e c h e l t I n l e t meets the c e n t r a l r e gion of the S t r a i t of Georgia through Agamemnon Channel and Malaspina S t r a i t . The flow of water i n t o S e c h e l t I n l e t i s r e s t r i c t e d by a very shallow s i l l which at lowest normal t i d e i s only 14 m deep ( P i c k a r d , 1961). The main bas i n of t h i s f j o r d has a maximum depth of 300 meters and a l e n g t h of 22 n a u t i c a l m i l e s (40.6 km) ( P i c k a r d , 1961). Maximum f r e s h water runoff i n t o the i n l e t occurs dur i n g the summer and winter months i n May and June, and, October, November and December ( P i c k a r d , 1961). The average s a l i n i t y i n J u l y 1957 was 25.8 ppt at 20 m and 28.58 ppt at 200 m. The temperature at the c o r r e s p o n d i n g depths was on average 11.1°C and 7.43°C ( P i c k a r d , 1961). I f we c o n s i d e r these values to be w i t h i n the normal range of s a l i n i t y f o r S e c h e l t I n l e t , then i t i s apparent that the water column i s f r e s h e r than e i t h e r the S t r a i t of Georgia or Saanich I n l e t which have t y p i c a l values of s a l i n i t y between 28 and 29 ppt at 20 m and 30 and 31 ppt at 200 m. The temperatures are s i m i l a r although s l i g h t l y warmer at 200 m i n S e c h e l t I n l e t . The bottom waters of Se c h e l t I n l e t are not known to develop anoxic c o n d i t i o n s although Narrows I n l e t , which i s adjacent to 13 S e c h e l t , can become very low i n oxygen. P i c k a r d (1961) found the oxygen l e v e l i n the bottom meter of Narrows I n l e t to be 0.15 mL L" 1 i n J u l y 1957. During the same sampling p e r i o d the oxygen minimum i n S e c h e l t I n l e t was l o c a t e d at 100 meters and co n t a i n e d 1.4 mL L " 1 . T h i s i m p l i e s that low oxygen-containing water present i n Narrows I n l e t , may be i n t r o d u c e d i n t o S e c h e l t I n l e t . D e spite the very shallow s i l l at the mouth of S e c h e l t I n l e t t here appears to be a strong e s t u a r i n e c i r c u l a t i o n between the f j o r d and a d j o i n i n g waters. The l a r g e supply of f r e s h water and the presence of oxygenated bottom waters i n d i c a t e a f a i r l y continuous movement of water. 2.2. S t a t i o n S e l e c t i o n Over the years the department of Oceanography at UBC has c o n s i s t e n t l y sampled the hydrographic parameters at s t a t i o n s G1545 and G1748 i n the S t r a i t of Georgia f o r both p h y s i c a l and b i o l o g i c a l r e s e a r c h ( f i g u r e 3). T h i s was an i n f l u e n t i a l f a c t o r i n d e c i d i n g on the s t a t i o n from which to c o l l e c t samples f o r t h i s p a r t i c u l a r study. S t a t i o n G1748 was sampled i n J u l y , August, September, and November 1985, and G1545 was maintained f o r the remainder of the study p e r i o d from December 1985 to September 1986, i n c l u d i n g October 1985. Both s t a t i o n s are w i t h i n c l o s e p r o x i m i t y of one another and l i e w i t h i n the c e n t r a l , deepest p o r t i o n of the S t r a i t , with a depth of approximately 400 meters ( t a b l e 1). Depth i s an important c h a r a c t e r i s t i c s i n c e the copepod under study overwinters below 200 m and reaches maximum c o n c e n t r a t i o n s i n the c e n t r a l r e g ion d u r i n g the f a l l and winter 14 months ( F u l t o n , 1972; Black, 1984). The s i l l at the mouth of Saanich I n l e t r e s t r i c t s the exchange of water thus a c t i n g as a b a r r i e r f o r the t r a n s p o r t of N. plumchrus , e s p e c i a l l y at times of the year when the copepods are below 75 m. The purpose of the S a t e l l i t e Channel s t a t i o n (Sate) was to sample the copepods which were e i t h e r e m igrating from, or immigrating i n t o , Saanich I n l e t ( f i g u r e 4). P h y s i c a l c h a r a c t e r i s t i c s were not measured at t h i s s t a t i o n . Two hydrographic s t a t i o n s were used i n Saanich I n l e t at the beginning of the sampling p e r i o d i n May 1985 ( t a b l e 2 ). The southern s t a t i o n , Saa0.8, i s s i t u a t e d i n S q u a l l y Reach and has a maximum depth of 216 m ( f i g u r e 4; t a b l e 1). The northern s t a t i o n , Saa9, which l i e s j u s t behind the s i l l to the northwest of P a t r i c i a Bay, has a maximum depth of 160 m ( f i g u r e 4 ). Both s t a t i o n s were used because of t h e i r l o c a t i o n at opposite ends of the i n l e t . The southern s t a t i o n i s l e s s i n f l u e n c e d by water movement from o u t s i d e the f j o r d and hence becomes anoxic sooner than Saa9. The northern s t a t i o n i s more a f f e c t e d by water exchanging through S a t e l l i t e Channel and t h e r e f o r e i s more exposed to the t r a n s p o r t of copepods. A c e n t r a l s t a t i o n (Saa3) was e s t a b l i s h e d to measure b i o l o g i c a l parameters ( f i g u r e 4 ). The l o c a t i o n i s f a r enough away from the s i l l that anoxic c o n d i t i o n s would most l i k e l y develop yet i t would r e c e i v e copepods through exchange with o u t s i d e waters. A l s o , i t was probable that the deep water renewal would reach Saa3 e n a b l i n g the examination of N. plumchrus with respect to the d i s p l a c e d low oxygen zone. Saa3 was not a hydrographic s t a t i o n due to l i m i t e d s h i p time. 15 S e c h e l t I n l e t was sampled i n November 1985, and i n February and August 1986. During the two winter months, s t a t i o n s Sc1, was sampled in the deeper regions of the i n l e t i n an attempt to estimate the s i z e of the o v e r w i n t e r i n g p o p u l a t i o n ( f i g u r e 3). In August 1986, three s t a t i o n s were used to allow f o r an e s t i m a t i o n of the p o p u l a t i o n v a r i a b i l i t y w i t h i n the i n l e t . 16 3. MATERIALS AND METHODS F i e l d data were c o l l e c t e d f o r a n a l y s i s of p o p u l a t i o n f l u c t u a t i o n s under v a r y i n g environmental c o n d i t i o n s i n Saanich I n l e t , S a t e l l i t e Channel, the S t r a i t of Georgia, and S e c h e l t I n l e t . Hydrographic data were of paramount importance i n determining whether or not changes i n the p h y s i c a l f e a t u r e s i n f l u e n c e d the d i s t r i b u t i o n of N. plumchrus. To enhance our understanding of the a b i l i t y of N. plumchrus to s u r v i v e low oxygen in t h e i r n a t u r a l h a b i t a t s , i t was necessary to conduct a s e r i e s of experiments i n which they were subjected to low l e v e l s of oxygen i n the l a b o r a t o r y . Sediment t r a p samples from Saanich I n l e t were a l s o examined f o r N. plumchrus to o b t a i n evidence of m o r t a l i t y r e s u l t i n g from unfavourable c o n d i t i o n s . 3.1. Hydrographic Data Hydrographic data were c o l l e c t e d approximately once a month from May 1985 through September 1986 ( t a b l e 2 & 3). The hydrographic s t a t i o n s Saa9 and Saa0.8, in Saanich I n l e t , correspond to the sediment t r a p mooring s t a t i o n s of Dr. S.E. C a l v e r t of the Department of Oceanography, UBC ( f i g u r e 4 ). P h y s i c a l c h a r a c t e r i s t i c s were measured at e i t h e r s t a t i o n G1545 or G1748 ( f i g u r e 3). S t a t i o n s other than the above mentioned were added f o r b i o l o g i c a l purposes so the hydrographic parameters were only sampled o c c a s i o n a l l y ( t a b l e 2 & 3). Temperature, s a l i n i t y , d e n s i t y and oxygen were the p h y s i c a l and chemical f e a t u r e s of i n t e r e s t . Temperature measurements were c a r r i e r ! out with e i t h e r r e v e r s i n g thermometers or a G u i d e l i n e 1 7 CTD probe, both of which have an accuracy of + 0.01°C or b e t t e r . Surface temperatures were measured from a bucket sample with a thermometer to w i t h i n 0.1°C. The CTD probe and the G u i d e l i n e A u t o s a l salinometer were used i n o b t a i n i n g c o n d u c t i v i t y values from which s a l i n i t y was estimated using the P r a c t i c a l S a l i n i t y S c a l e (1978). The salinometer determinations have an accuracy of + 0.003 ppt i n the 2-42 ppt s a l i n i t y range. These val u e s were used to v e r i f y CTD measurements. Den s i t y , expressed as at, was c a l c u l a t e d with the UNESCO Equation of State of Seawater from temperature and s a l i n i t y v a l u e s . Oxygen l e v e l s were determined with a m o d i f i e d Winkler t i t r a t i o n method on board s h i p ( C a r r i t t & Carpenter, 1966). The above parameters were measured at 9 to 12 depth i n t e r v a l s from the s u r f a c e to near the bottom. The hydrographic data are being c o l l e c t e d as pa r t of an ongoing r e s e a r c h p r o j e c t at UBC. A d i s c u s s i o n of the techniques can be found i n the department of Oceanography UBC data r e p o r t s , 54 & 55 (1985 & 1986) . 3.2. Zooplankton Sampling Zooplankton samples were c o l l e c t e d from Saanich I n l e t , S a t e l l i t e Channel, the S t r a i t of Georgia, and on o c c a s i o n , S e c h e l t I n l e t ( t a b l e 2 & 3). V e r t i c a l and h o r i z o n t a l nets were hauled at v a r i o u s depths depending on the time of year, the oxygen p r o f i l e , and the documented l i f e h i s t o r y p a t t e r n s of N. plumchrus. V e r t i c a l haul samples were i n i t i a l l y c o l l e c t e d using a SCOR 18 net with an i n s i d e diameter of 57 cm and a 333 nm n i t e x mesh. For the September 1985 c r u i s e , a m o d i f i e d SCOR net (mSCOR) was co n s t r u c t e d to in c l u d e an N.I . 0 . ( N a t i o n a l I n s t i t u t e of Oceanography, U.K.) t h r o t t l i n g mechanism ( f i g u r e 5 ). The mSCOR net was of the same diameter but was made of 293 jum n i t e x n e t t i n g . T h i s net was used f o r a l l subsequent v e r t i c a l h a u l s . Once on s t a t i o n , the mSCOR net was lowered from the s t a t i o n a r y v e s s e l at 1 m s e c " 1 and r a i s e d to the s u r f a c e at 0.5 m s e c " 1 . The speed of the haul v a r i e d somewhat with d i f f e r e n t winch o p e r a t o r s . The d u r a t i o n of the haul depended on the depth being sampled. An echosounding was used to o b t a i n a maximum depth f o r the area so that the v e r t i c a l hauls c o u l d be kept w i t h i n seven to ten meters of the bottom to a v o i d damage to the net. Clarke-Bumpus nets, m o d i f i e d a c c o r d i n g to Paquette and Frol a n d e r (1957), were used f o r the h o r i z o n t a l tows. A 500 Mm net was at t a c h e d to a metal housing which had an i n t e r n a l diameter of 12.4 cm. The i m p e l l e r blade mounted a c r o s s the open area was l i n k e d to a mechanical readout on the flowmeter from which the volume of water c o u l d be c a l c u l a t e d . Three to four nets were a t t a c h e d to the wire at a time and were opened and c l o s e d by a s e r i e s of messengers. C-B nets were towed f o r twenty minutes at a s h i p speed of about 1.5 knots, to maintain a 30° ( + 5°) wire a n g l e . A c a l i b r a t i o n value of 0.0043 m 3 « r e v " 1 was used to c a l c u l a t e the volume f i l t e r e d through the C-B nets (Yentsch & Duxbury, 1956; Regan, 1963). The c a l i b r a t i o n value was roughly t e s t e d using two of the four C-B n e t s . Each net was towed by hand f o r a d i s t a n c e of 15 meters and the number of 19 r e v o l u t i o n s were recorded f o r s i x r e p l i c a t i o n s . The average determined f o r net #23 was 0.0041 m 3 « r e v ~ 1 and f o r net #31, 0.0047 m 3 « r e v " 1 . T h i s was c o n s i d e r e d to be i n f a i r l y good agreement with the documented c a l i b r a t i o n v a l u e . A s e r i e s of s i x r e p l i c a t e tows were run i n J u l y 1986 to o b t a i n an estimate of the v a r i a t i o n between samples. P a i r e d v e r t i c a l haul r e p l i c a t e s were taken with the m o d i f i e d SCOR net on s e v e r a l o c c a s i o n s i n order to o b t a i n an estimate of the v a r i a t i o n among samples. Determinations of the percent acceptance of water i n t o the mSCOR net was measured by comparing the r e v o l u t i o n s of the flowmeter from i n s i d e the net to that of the flowmeter i n the absence of the net ( t a b l e 4 ). As recommended by Gehringer and Aron (1968), the flowmeter was p l a c e d midway between the rim of the net and the c e n t e r . An average of- 46% acceptance was used to c o r r e c t copepod counts c a l c u l a t e d f o r each v e r t i c a l haul (volume f i l t e r e d = 7rr 2d«0.46, where, r=radius of the net, d=distance h a u l e d ) . The depth i n t e r v a l s sampled with the v e r t i c a l haul net o c c a s i o n a l l y overlapped at a given s t a t i o n (e.g. June 1986, G1545, 200-300 m and 200-395 m samples). The c a l c u l a t e d number of copepods per c u b i c meter, f o r each depth i n t e r v a l , are r e p o r t e d i n the raw data t a b l e ( t a b l e 13 & 15) but f o r the v e r t i c a l d i s t r i b u t i o n f i g u r e s ( f i g u r e s 39, 42-45, 48-49) the o v e r l a p i s taken i n t o c o n s i d e r a t i o n . Both the depth and number of copepods are s u b t r a c t e d from the sample va l u e s at the depth i n t e r v a l c o n t a i n i n g the h i g h e s t c o n c e n t r a t i o n of copepods ( i . e . June 1986, G1545, the number of copepods between 200-300 m was s u b t r a c t e d from the number c o l l e c t e d between 200-395). The 20 r e s u l t a n t c a l c u l a t i o n i s the number per c u b i c meter between 200 and 300 m and between 300 and 395 m. During the November 1986 c r u i s e , the c a l c u l a t e d depth of tow f o r the C-B nets was t e s t e d with a bathykymograph ( f i g u r e 6). The instrument was sent down to 150 m f o r f i v e minutes to o b t a i n a b a s e l i n e readout. The depths recorded on the bathykymograph during the two C-B tows i n d i c a t e d a v a r i a t i o n of a maximum of 10 meters below the c a l c u l a t e d depth when three nets were on the wire ( f i g u r e 6). The Bioness sampler owned by the I n s t i t u t e of Ocean Science at P a t r i c i a Bay was u t i l i z e d on March 5, 1986 f o r the c o l l e c t i o n of zooplankton at s t a t i o n Saa3. The Bioness was towed o b l i q u e l y f o r 15 minutes at a speed of 2 knots. F i v e nets were r e l e a s e d at i n t e r v a l s of 25 and 50 m ( t a b l e 17). The volume of water f i l t e r e d was determined f o r the 0.25 m2 net opening assuming a 90% acceptance of water, although i t may be s l i g h t l y lower (Dave Mackas, p e r s . comm.). 3.3. Treatment of Net Haul Samples Specimens were pr e s e r v e d immediately a f t e r capture i n 3-5% f o r m a l i n , b u f f e r e d with c a l c i u m carbonate. Afterwards the samples were examined f o r one s p e c i e s of c a l a n o i d copepod, N. plumchrus ( f i g u r e 2 ). An M5 Wild L e i t z d i s s e c t i n g microscope was used f o r counting and s p e c i e s i d e n t i f i c a t i o n . Only the CIV, CV, and CVI stages were examined s i n c e an a n a l y s i s of the n a u p l i i to CIII stages would c o n t r i b u t e l i t t l e to the q u e s t i o n s being posed. I t i s a l s o more d i f f i c u l t to d i s t i n g u i s h the 21 n a u l p i i - C I I I stages from other c a l a n o i d copepods than i t i s to i d e n t i f y the CIV-CVI stages of t h i s s p e c i e s . O c c a s i o n a l l y the s i z e of the CIV and CV N. plumchrus was smal l e r than average so i t was necessary to remove the 5th p a i r of l e g s f o r i d e n t i f i c a t i o n . T h i s allowed s e p a r a t i o n of the s p e c i e s from Calanus m a r s h a l l a e . The taxonomic manuscript by Gardner and Szabo (1982) was the main r e f e r e n c e f o r s p e c i e s i d e n t i f i c a t i o n . For samples c o n t a i n i n g l a r g e numbers of N. plumchrus a Folsom s p l i t t e r was used to s p l i t the sample i n t o f o u r t h s . Since the samples c o l l e c t e d i n Saanich I n l e t r a r e l y exceeded three hundred specimens, the Folsom s p l i t t e r was only used f o r S t r a i t of Georgia counts. Each of the four sub-sample chambers were examined a l t e r n a t e l y d u r i n g the count. Ten r e p l i c a t e counts of a known q u a n t i t y of N. plumchrus (318 CVs) were used to t e s t the Folsom s p l i t t e r . The l a r g e s t underestimate of the a c t u a l t o t a l averaged 11.8% (chamber A). The maximum overestimate averaged 8.4% of the t o t a l (chamber C). 3.4. C o l l e c t i o n and Maintenance of L i v e Copepods L i v e stage f i v e copepodites were c o l l e c t e d monthly, from May to November 1986, f o r oxygen t o l e r a n c e t e s t s . A l l equipment used i n h a n d l i n g and storage of copepods were a c i d washed and r i n s e d with d i s t i l l e d water. The l i v e specimens were removed from the co n c e n t r a t e d samples with a g l a s s p i p e t t e and t r a n s f e r r e d i n t o thermos f l a s k s c o n t a i n i n g 3.5 l i t e r s of sea water. A maximum of 55 specimens were p l a c e d i n t o each thermos so that the d e n s i t y of copepods i n c a p t i v i t y d i d not exceed 14 22 organisms L~ 1 . The f l a s k s were s t o r e d aboard s h i p i n the r e f r i g e r a t o r (4°C) u n t i l the end of the c r u i s e at which time they were t r a n s p o r t e d to a coldroom (4°C or 7°C) at UBC. The copepods were h e l d at 4°C d u r i n g experiments #1-5 and subsequently they were h e l d at 7°C. For the l a b o r a t o r y t e s t s , sea water was c o l l e c t e d from the depth range occupied by the copepods e i t h e r i n the S t r a i t of Georgia or Saanich I n l e t . The sea water was f i l t e r e d with an 8 um net i n t o carboys to remove smal l d e b r i s . The f l a s k water c o n t a i n i n g the copepods was changed on two occ a s i o n s so that the maximum p e r i o d of time spent i n the o r i g i n a l water was 73 days (the water c o l l e c t e d May 12th was changed J u l y 24th). No b a c t e r i c i d e was used. The pH of the water c o n t a i n e d i n the f l a s k s was measured with the Accumet model 140 pH meter at the end of the c a p t i v i t y p e r i o d . Values ranged between a pH of 7.4 and 8.0. Some of the l i v e copepods were p l a c e d i n sea water taken from the Department of Zoology sea water o u t l e t d u r i n g the experimental runs. The s a l i n i t y of the water was 27.5 ppt, w i t h i n the range of the sea water from which the copepods were c o l l e c t e d . No adverse e f f e c t s from t h i s sea water were apparent in the c o n t r o l copepod group. While i n c a p t i v i t y the copepods were fed every 3 to 5 days with T h a l a s s i s i r a w e i s s f l o g i i , I s o c h r y s i s galbana, Chaetoceros  didymus, and C. g r a c i l i s . The phytoplankton were s u p p l i e d by the North East P a c i f i c C u l t u r e c o l l e c t i o n at UBC. T. w e i s s f l o g i i and I_. galbana are known to be eaten by N. plumchrus ( F r o s t et a l . , 1983) so, i f there was an absence of f e c a l p e l l e t s i n the f l a s k s , i t c o u l d be a t t r i b u t e d to a l a c k of f e e d i n g . One thermos 23 of copepods, c o l l e c t e d i n October and the copepods c o l l e c t e d i n June 1987, were not p r o v i d e d with food. T h i s enabled a comparison of the m o r t a l i t y r a t e of the s t a r v e d October copepods to the f e d copepods while h e l d i n c a p t i v i t y . The June 1987 copepods were only h e l d i n c a p t i v i t y f o r 8 days so i t was presumed that t h e i r h e a l t h was not impaired by a l a c k of food. 3.5. Experimental Procedures P r i o r to each experiment ten copepods were p l a c e d i n four separate 100 mL beakers f o r 12 hours to a d j u s t to the l i g h t . Water in the t e s t carboy was bubbled with n i t r o g e n f o r an average of 15 hours to reduce the oxygen c o n c e n t r a t i o n . The p e r i o d of bubbling depended on the l e v e l of oxygen r e q u i r e d although i t was not p o s s i b l e to o b t a i n c o n s i s t e n t oxygen l e v e l s f o r a given time of exposure to n i t r o g e n . Water i n the c o n t r o l carboys was n e i t h e r a e r a t e d nor s t r i p p e d of oxygen. Oxygen was lowered to l e v e l s s i m i l a r to those found at o v e r w i n t e r i n g depths i n the S t r a i t to ensure that these l e v e l s d i d not have any d e l e t e r i o u s a f f e c t s on the copepods. The b a s i c set-up f o r each experiment c o n s i s t e d of four 500 mL g l a s s separatory f u n n e l s , two 20 l i t e r p olycarbonate carboys, s i l i c o n s t o p p e r s , a valve to c o n t r o l the flow of n i t r o g e n , and a p i e c e of p l a s t i c tubing a t t a c h e d to the top of the funnels f o r the removal of water samples ( f i g u r e 7 ). Two separatory f u n n e l s were a t t a c h e d to the t e s t carboy and the other two r e c e i v e d water from the c o n t r o l carboy. Ten copepods were added to each funnel from the 100 mL beakers. Once the stoppers were i n p l a c e 24 a i r bubbles were removed from the l i n e s and the water was f l u s h e d through the f u n n e l s . A 250 mL water sample was c o l l e c t e d from the top and analyzed f o r oxygen using the Winkler t i t r a t i o n method. Oxygen l e v e l s were lowered g r a d u a l l y over the twelve hour p e r i o d of the f i r s t s i x experiments ( t a b l e 5). Every three hours, water samples were c o l l e c t e d and the funnels f l u s h e d to prevent b u i l d up of m e t a b o l i t e s . Owing to the r e l a t i v e l y l a r g e volume of water f o r the number of copepods, i t d i d not appear necessary to r e p l a c e water every 3 hours. In a d d i t i o n , although a gradual decrease i n oxygen was perhaps a b e t t e r r e p r e s e n t a t i o n of c o n d i t i o n s i n the n a t u r a l environment, i t was necessary to reduce the v a r i a b i l i t y i n the oxygen l e v e l s being t e s t e d ( t a b l e 5). Hence, the l a s t seven experiments were only f l u s h e d at the beginning of the experiment so that copepods were exposed to a more constant oxygen l e v e l . Water samples were drawn f o r oxygen a n a l y s i s at the beginning and end of the twelve hour p e r i o d i n these i n s t a n c e s . Oxygen values ranged from 0.26 to 2.24 mL L~ 1 d u r i n g t e s t s ( t a b l e 5). Oxygen l e v e l s t e s t e d i n the c o n t r o l s v a r i e d from 4.20 to 6.94 mL L " 1 . O r i g i n a l l y the two t e s t funnels were intended to be r e p l i c a t e s but s i n c e the oxygen v a l u e s o f t e n d i f f e r e d by as much as 0.28 mL L ~ 1 , each was t r e a t e d as a separate t e s t . A l s o , the copepods i n each of the t e s t f u n n e l s were not n e c e s s a r i l y c o l l e c t e d on the same date ( t a b l e 5). I t had been assumed that a l l of the CVs would respond to low oxygen i n a s i m i l a r manner. However, i t became apparent that copepods c o l l e c t e d from May through to November d i d not demonstrate the same l e v e l of oxygen 25 t o l e r a n c e . The experiments were run f o r 24, 21, 18, or 12 hour d u r a t i o n s ( t a b l e 5). Copepods su b j e c t e d to low oxygen were examined p r i o r to c o n t r o l organisms. Each copepod was c a t e g o r i z e d as h e a l t h y , dying, or dead based on i t s l e v e l of a c t i v i t y . I f the copepod showed no s i g n s of movement the prosome was examined under a d i s s e c t i n g microscope f o r a h e a r t b e a t . I f there was no apparent heartbeat a f t e r 60 seconds of o b s e r v a t i o n the copepod was r e p o r t e d as dead. Slow i r r e g u l a r h e artbeats coupled with a lack of a c t i v i t y and cloudy t i s s u e s were the c r i t e r i a f o r c l a s s i f y i n g the organism as "dying". To determine i f recovery was p o s s i b l e , copepods c a t e g o r i z e d as "dying" were h e l d f o r o b s e r v a t i o n f o l l o w i n g two experiments i n which copepods were found i n t h i s s t a t e . One out of the s i x copepods observed, recovered, 5-7 days a f t e r the experiment. In the case of the dead specimens, the copepods were p l a c e d i n separate beakers to determine the behavior of t h i s s p e c i e s as a s e t t l i n g p a r t i c l e . T h i s was r e l e v a n t to the sediment t r a p data. 3.6. Sediment Trap Samples P a i r e d sediment t r a p samplers at s t a t i o n Saa9 were moored at three depths, shallow (45 m), mid (110 m), and deep (150 m) water. At s t a t i o n Saa0.8 the sediment t r a p s were deployed at 50, 135, and 180 m. Two t r a p s were a t t a c h e d to the main cable at each depth. P r i o r to deployment one t r a p was f i l l e d with a 30% s o l u t i o n of NaCl to prevent the l o s s of sediment laden water by i n c r e a s i n g the d e n s i t y g r a d i e n t between the t r a p water and the 26 surrounding water. The other t r a p was f i l l e d with a 0.5% s o l u t i o n of sodium a z i d e (NaN 3) to preserve the sample as i t s e t t l e d i n t o the chamber and to reduce the l o s s of t r a p c o n t e n t s . Whole organisms or p i e c e s of v a r i o u s body p a r t s were separated from the sediment t r a p samples and then examined f o r N. plumchrus. Samples from s t a t i o n s Saa9 and Saa0.8 were examined from March through to November 1985 and from June through to September 1986. 3.7. S t a t i s t i c a l Methods Neocalanus plumchrus was sampled on a .monthly b a s i s at f i x e d s t a t i o n s i n the S t r a i t of Georgia, Saanich I n l e t , and S e c h e l t I n l e t . A f i x e d e f f e c t s two-way ANOVA was used to t e s t f o r d i f f e r e n c e s among the means between s t a t i o n s and months i n the v e r t i c a l haul samples. The unbalanced design a v a i l a b l e through the GENLIN program at UBC (MTS computing system), was u t i l i z e d i n the 2-way ANOVA c a l c u l a t i o n s . A l l t e s t s were run at the 5% l e v e l , i n c l u d i n g the B a r t l e t t Chi-squared t e s t f o r homogeneity of v a r i a n c e and the S c h e f f e , B o n f e r r o n i , and Minimal t e s t s f o r sources of v a r i a t i o n . A s i n g l e - f a c t o r ANOVA was used to compare the mean number of copepods per cub i c meter c o l l e c t e d i n the h o r i z o n t a l samples at s t a t i o n Saa9 i n J u l y 1986. To meet the assumptions of the ANOVA t e s t s i t was necessary to transform the t o t a l numbers from the v e r t i c a l hauls and the number m~3 from the h o r i z o n t a l tows. T y p i c a l l y data c o l l e c t e d f o r copepod p o p u l a t i o n s t u d i e s are 27 transformed using log(x+1) (Evans and S e l l , 1983). For N. plumchrus, the data transformed i n t h i s manner d i d not r e s u l t i n the independence of the v a r i a n c e from the mean t h e r e f o r e the Power Law t r a n s f o r m a t i o n was used. The Power Law t r a n s f o r m a t i o n was f i r s t proposed by T a y l o r (1961) f o r c o n t a g i o u s l y d i s t r i b u t e d i n v e r t e b r a t e taxa i n which the l o g of the v a r i a n c e i n c r e a s e d with the l o g of the mean. A l i n e a r r e g r e s s i o n of the l o g of the v a r i a n c e a g a i n s t the l o g of the mean was c a l c u l a t e d f o r the 22 p a i r s of r e p l i c a t e , v e r t i c a l haul samples c o l l e c t e d i n the S t r a i t of Georgia, Saanich I n l e t , and S e c h e l t I n l e t ( f i g u r e 8 ) . The equation of the l i n e f i t t e d to l o g s 2 / l o g x was y=0.07+1.60x, R 2=0.93. From t h i s the Power Law t r a n s f o r m a t i o n , X P=Y, was determined from the slope ( b ) , where b=1.60, p=1-b/2, and Y i s the transformed v a l u e . The Power Law t r a n s f o r m a t i o n c a l c u l a t e d f o r t h i s s p e c i e s i s X0'2 which i s a l s o the power t r a n s f o r m a t i o n recommended by Downing et a l . (1987). 28 4. RESULTS 4.1. A n a l y s i s of the P h y s i c a l Data In t h i s s e c t i o n , the p h y s i c a l data f o r the v a r i o u s r e g i o n s are presented. The v a r i a t i o n s i n s a l i n i t y , temperature, d e n s i t y , and oxygen, r e l e v a n t to the study of N. plumchrus, are d e s c r i b e d with respect to the p o s s i b l e c a u s a t i v e f a c t o r s . The i n f l u e n c e of the P a c i f i c Ocean i s e s p e c i a l l y n o t i c e a b l e i n the S t r a i t of Georgia and Saanich I n l e t during c e r t a i n times of the year. Because of the extremely shallow s i l l i n S e c h e l t I n l e t , t h i s f j o r d remains q u i t e d i f f e r e n t from the two other study areas. 4.1.1. Saanich I n l e t Saanich I n l e t showed d i s t i n c t i v e seasonal trends i n 1985 and 1986. The c o o l , low s a l i n i t y waters c o o l e d by winter a i r sank and mixed with bottom waters at Saa9 i n March ( f i g u r e 9, 10 & 11). T h i s water c o n t a i n e d more oxygen than i n p r e v i o u s months ( f i g u r e 12). At Saa0.8 c o o l n e a r - s u r f a c e waters, were not s u f f i c i e n t l y dense to sink below 150 m and r e p l a c e warmer bottom waters from January to J u l y ( f i g 20 & 21). Hence, bottom waters at Saa0.8 were c h a r a c t e r i z e d by anoxic c o n d i t i o n s and s a l i n i t i e s between 31.03 and 31.20 ppt ( f i g u r e s 19 & 22). Oxygen l e v e l s began to d e c l i n e at Saa9 i n A p r i l through to August, reaching a minimum of 0.31 mL L~-1 i n August at a depth 29 of 140 m. From May to J u l y n e a r - s u r f a c e s a l i n i t y decreased, presumably as a r e s u l t of F r a s e r R i v e r r u n o f f . Exchange of water was g r e a t e r above the s i l l than below because the water was not s u f f i c i e n t l y dense to r e p l a c e the bottom waters. Small f l u c t u a t i o n s i n s a l i n i t y and temperature at deeper depths, and the p r o g r e s s i v e d e c l i n e i n oxygen i n t o August, i n d i c a t e d t hat the water was s t a g n a t i n g ( f i g u r e 12). A supply of f r e s h water from Goldstream R i v e r and perhaps the F r a s e r and Cowichan R i v e r s , lowered s a l i n i t y i n the top 50 m from May to August at Saa0.8. In May, s a l i n i t y was lower at Saa0.8 than Saa9. Despite added f r e s h water, p e r s i s t e n c e of anoxic c o n d i t i o n s suggested that e s t u a r i n e c i r c u l a t i o n was not strong enough to c i r c u l a t e the e n t i r e water column ( f i g u r e 22). Due to l i m i t e d s h i p time, the hydrographic parameters were measured at Saa3 only i n August 1985 and 1986. In 1985, the oxygen c o n c e n t r a t i o n at 165 m was 0.11 mL L" 1 and decreased to 0.02 mL L" 1 at 185 m ( f i g u r e 17). T h i s suggested that below 185 m the water was anoxic and that the i n l e t was anoxic throughout i t s l e n g t h . In September, dense, high s a l i n i t y water was present below 75 m at Saa9 and Saa0.8. C h a r a c t e r i s t i c s of t h i s water i n d i c a t e d the onset of the deep water renewal. Of p a r t i c u l a r i n t e r e s t was the marked displacement of low oxygen water from the bottom depths at both Saa9 and Saa0.8. At Saa0.8 the low oxygen zone was s i t u a t e d between 75 and 160 m during September ( t a b l e 9). The oxygen content of the water ranged from 0.02 mL L~ 1 to a high of 0.26 mL L" 1 ( t a b l e 9). In October oxygen val u e s between 100 and 160 m ranged between 0.00 mL L" 1 and 0.17 mL L - 1 . Water 3 0 from the bottom 40 m was r e p l a c e d with water c o n t a i n i n g an average of 0.38 mL 0 2 L ~ 1 . At Saa9 the low oxygen zone was d i s p l a c e d between 75 and 120 m i n September and October ( t a b l e 16). During both months minimum oxygen c o n c e n t r a t i o n s at 75 m were lower than that recorded i n August at 140 m. I t seems probable that t h i s low oxygen water was being f o r c e d from the d i r e c t i o n of s t a t i o n Saa0.8 where anoxic c o n d i t i o n s had developed and were subsequently d i s p l a c e d . Based on the change i n oxygen content below 150 m at Saa0.8 and Saa9 the volume of i n f l o w i n g new water (between August 7 and September 17) was estimated to be 2.9 x 10 B m3 (appendix A). Since the water l e v e l i s not a f f e c t e d by an exchange, the i n f l o w of water would have been balanced by an outflow of o l d , l e s s dense water (LeBlond, 1983). The dense, high s a l i n i t y water continued to i n t r u d e as f a r as Saa0.8 i n December 1985. Maximum annual s a l i n i t y and d e n s i t y l e v e l s were reached d u r i n g t h i s time. A s s o c i a t e d with the high d e n s i t y water was a f u r t h e r i n c r e a s e i n the l e v e l of oxygen below 75 m. Oxygenated waters in t r o d u c e d d u r i n g the f l u s h i n g event i n 1985, p e r s i s t e d i n t o March 1986 at Saa0.8 ( f i g u r e 26). At a depth of 190 m water contained 0.50 mL L~ 1 and j u s t above t h i s depth, the oxygen minimum zone s t i l l e x i s t e d ( t a b l e 10). From A p r i l to June, oxygen f e l l below 0.20 mL L" 1 i n deeper depths. Anoxic c o n d i t i o n s were found below 190 m i n J u l y and below 180 m i n August, i n c o n t r a s t to 1985 i n which anoxic c o n d i t i o n s were developed i n January ( f i g u r e 22). There may have been a small i n j e c t i o n of water from the s u r f a c e or from the d i r e c t i o n of the 31 s i l l p r e v e n t i n g complete s t a g n a t i o n during the s p r i n g and e a r l y summer ( f i g u r e 24). At Saa9 oxygen val u e s between 120 and 140 m d e c l i n e d to lower l e v e l s than i n 1985 but tended to f l u c t u a t e from month to month ( f i g u r e 16). In A p r i l , oxygen l e v e l s were as low as 0.35 mL L" 1 at 140 m ( t a b l e 7 ) . They rose i n May and June, but decreased to 0.20 mL L" 1 i n J u l y . The oxygen l e v e l at 140 m i n c r e a s e d again i n August to 0.75 mL L~ 1 perhaps due to an i n t r u s i o n of a small volume of dense, oxygenated water. Water samples c o l l e c t e d at Saa3 i n August 1986 from 140 to 200 m demonstrated the presence of an oxygen minimum (0.31 mL L" 1) at 170 m ( t a b l e 8 ) . The higher oxygen content below t h i s depth was a f u r t h e r i n d i c a t i o n t h at a small volume of dense water had i n t r u d e d i n e a r l y August. The deep water renewal had undoubtedly commenced by September 1986, c h a r a c t e r i z e d by i n t r u d i n g high s a l i n i t y , low temperature water, and displacement of low oxygen water throughout the ba s i n ( f i g u r e 13, 14, 23 & 24). The high s a l i n i t y i n t r u s i o n began to d e c l i n e i n December u n l i k e the p a t t e r n seen in December 1985 when the high s a l i n i t y water was at a maximum. Water from the September 1986 deep water i n t r u s i o n c o n t a i n e d oxygen l e v e l s as high as 1.2 mL L" 1 at Saa0.8 but lower c o n c e n t r a t i o n s of oxygen were found i n the deep mixed l a y e r i n subsequent months ( f i g u r e 25 & 26). Low oxygen water which was d i s p l a c e d to depths between 75 and 160 m i n September, remained anoxic at 140 m. In October, the oxygen minimum zone was s i t u a t e d between 100 and 160 m and -was not anoxic although values were as low as 0.18 mL L" 1 at 120-140 m ( t a b l e 10). 32 At Saa9, bottom waters were d i s p l a c e d to a depth of 75 m i n September. T h i s d i s p l a c e d water was c h a r a c t e r i z e d by low oxygen l e v e l s of 0.77 mL L~ 1 ( t a b l e 7 ) . In October, an oxygen minimum of 0.89 mL L " 1 was l o c a t e d at 120 m. Owing to the d e c l i n e i n the volume of i n t r u d i n g high s a l i n i t y water i n December, oxygen l e v e l s i n the deep waters remained r e l a t i v e l y constant from November to December. A comparison of the deep water renewal i n 1985 to the i n t r u s i o n i n 1986 i n d i c a t e d that d i s p l a c e d water and i n t r u d i n g water i n 1986 con t a i n e d higher l e v e l s of oxygen. T h i s may have r e s u l t e d from a grea t e r degree of mixing between stagnant bottom waters and incoming water, or from the presence of a sm a l l e r volume of oxygen-poor water p r i o r to the renewal. The deep water renewal may have s t a r t e d i n August 1986 as i n d i c a t e d by the higher c o n c e n t r a t i o n of oxygen at 120 and 140 m at Saa9 and a l s o the displacement of a narrow low oxygen zone at Saa3. 4.1.2. S t a t i o n G1748 & G1545 An examination of s a l i n i t y and temperature c h a r a c t e r i s t i c s at s t a t i o n s G1748 and G1545 i n d i c a t e a marked s i m i l a r i t y i n water p r o p e r t i e s at the hydrographic s t a t i o n s i n the S t r a i t of Georgia and Saanich I n l e t . T h i s can be l a r g e l y a t t r i b u t e d to exchange of water between the S t r a i t of Georgia and Saanich I n l e t , and the i n f l u e n c e of the P a c i f i c Ocean to both ar e a s . Bathymetry and f r e s h water supply are the main f a c t o r s c o n t r i b u t i n g to d i f f e r e n c e s between the two areas.-Winter months, represented by February, were c h a r a c t e r i z e d 33 by c o o l temperatures from the s u r f a c e to a depth of approximately 200 m ( f i g u r e 28). Water cooled d u r i n g winter r e p l a c e d the warmer bottom waters i n March. As summer approached, shallow depths were warmed by i n c r e a s e d i n s o l a t i o n but the deeper depths remained f a i r l y uniform w i t h i n the 8°C range. The temperature of the water at deeper depths, g r a d u a l l y rose d u r i n g summer and reached l e v e l s above 9°C by October. Input from the F r a s e r River decreased the s a l i n i t y i n the upper l a y e r s from May to September 1985 ( f i g u r e 27). S a l i n i t y remained f a i r l y constant throughout the water column u n t i l September. High s a l i n i t y waters, presumably upwelled o f f the west coast from A p r i l to August (Herlinveaux, 1962; LeBlond, 1983; P i c k a r d & Emery, 1982), s t a r t e d to a r r i v e at the S t r a i t of Georgia s t a t i o n at t h i s time. S a l i n e waters continued to move i n d u r i n g December and reached a maximum volume. The s a l i n i t y range of the i n t r u d i n g water was s i m i l a r to v a l u e s at Saa9 d u r i n g the renewal but high s a l i n i t y waters were found at much deeper depths at s t a t i o n G1545. A s s o c i a t e d temperatures and d e n s i t i e s were a l s o very s i m i l a r to those at Saa9 suggesting that P a c i f i c Ocean water was r e p l a c i n g the bottom water at both s t a t i o n s ( f i g u r e 28 & 29). The S t r a i t of Georgia remained oxygenated throughout the e n t i r e year ( f i g u r e 30). A minimum of 2.77 mL 0 2 L" 1 was measured i n February 1985 from samples c o l l e c t e d at 400 m ( t a b l e 11). Oxygen l e v e l s present i n the deep water exchanged from September to December, co n t a i n e d a minimum of 3.35 mL L~ 1 at 300 m. Values much lower than t h i s were found at both s t a t i o n s i n Saanich I n l e t d u r i n g the renewal as a r e s u l t of mixing with 34 r e s i d e n t low oxygen-containing waters. S i m i l a r seasonal trends o c c u r r e d i n 1986 ( f i g u r e 31,32, & 33). The water mass i n t r u d i n g i n t o G1545 i n f a l l and e a r l y winter c o n t a i n e d a minimum of 3.15 mL 0 2 L" 1 at 300 m which was a l s o the minimum for the year ( t a b l e 12, f i g u r e 34). 4.1.3. S e c h e l t I n l e t S e c h e l t I n l e t was sampled on three o c c a s i o n s , November 1985, and February and August 1986. Hydrographic parameters were measured down to 250 m (maximum depth was 293 m) at s t a t i o n Sc1 in November 1985. Compared to s t a t i o n Saa9 i n November 1985, the water column at Sc1 was g e n e r a l l y f r e s h e r (20.8-28.7 ppt) at a l l depths. Temperatures tended to be somewhat c o o l e r at Sc1 than Saa9 but only by <1°C. The d e n s i t y remained lower than that measured i n Saanich I n l e t or the S t r a i t of Georgia as a r e s u l t of the lower s a l i n i t i e s ( f i g u r e 35). Oxygen l e v e l s were above 2.40 mL L" 1 between 150 and 250 m i n c o n t r a s t to Saa9 and Saa0.8 where they f e l l below 0.65 mL L - 1 . In February 1986 hydrographic f e a t u r e s were measured at s t a t i o n Sc1 to a depth of 240 m (9 meters above the bottom). S a l i n i t y v a l u e s were s t i l l lower than Saa9, based on March 1986 data f o r Saanich I n l e t ( f i g u r e 36). Temperatures were f a i r l y homogeneous throughout the water column with the e x c e p t i o n of very c o l d temperatures at the s u r f a c e ( f i g u r e 36). D i s s o l v e d oxygen l e v e l s d i d not d e c l i n e below 2.75 mL L" 1 ( f i g u r e 36). In August 1986, p h y s i c a l data were c o l l e c t e d at s t a t i o n s Sc2 and Sc2a. Both s t a t i o n s showed seasonal warming in the upper 35 50 m and a strong d e n s i t y s t r a t i f i c a t i o n ( f i g u r e 37 & 38). Fresh water was present at the su r f a c e and maximum s a l i n i t i e s around 28.8 ppt occurred at depth. The oxygen d i d not f a l l below 2.40 mL L" 1 at e i t h e r s t a t i o n ( f i g u r e 37 & 38). With r e f e r e n c e to Saanich I n l e t s t a t i o n s Saa0.8 and Saa9, Se c h e l t I n l e t d i d not develop low oxygen c o n d i t i o n s (<1.0 mL L" 1) d u r i n g winter and summer months measured. The February and August sampling p e r i o d s d i d not c o i n c i d e with the time of maximum f r e s h water run-off ( P i c k a r d , 1961) yet the water column remained lower i n s a l i n i t y and d e n s i t y than e i t h e r Saanich I n l e t or the S t r a i t of Georgia. 4.2. A n a l y s i s of Net Haul Samples Neocalanus plumchrus CIV, CV, and CVI specimens were obtained from v e r t i c a l net hauls c o l l e c t e d i n the S t r a i t of Georgia, Saanich I n l e t , and S e c h e l t I n l e t . The main o b j e c t i v e of the sampling was to compare c o n c e n t r a t i o n s of copepods from the three areas to determine i f there were s i g n i f i c a n t d i f f e r e n c e s i n t h e i r abundance. The hydrographic parameters were examined as a p o s s i b l e f a c t o r c o n t r i b u t i n g to the observed d i f f e r e n c e s i n d i s t r i b u t i o n and d e n s i t y of N. plumchrus. H o r i z o n t a l net hauls i n Saanich I n l e t were used to determine the v e r t i c a l d i s t r i b u t i o n of the s p e c i e s . 36 4.2.1. S t r a i t of Georgia V e r t i c a l Hauls The v e r t i c a l d i s t r i b u t i o n and c o n c e n t r a t i o n of Neocalanus  plumchrus i s re p o r t e d f o r each month sampled i n the S t r a i t of Georgia. Seasonal changes i n t h e i r d i s t r i b u t i o n are evident as report e d i n e a r l i e r papers (Gardner, 1972; F u l t o n , 1973). The S t r a i t of Georgia was f i r s t sampled i n J u l y 1985 to a depth of 150 m where <1 copepod nr 3 was found ( t a b l e 13; f i g u r e 39). T h i s suggested that the p o p u l a t i o n was a l r e a d y i n h a b i t i n g o v e r w i n t e r i n g depths. The August samples v e r i f i e d the presence of a deep water p o p u l a t i o n below 150 m ( f i g u r e 39). The number of o v e r w i n t e r i n g copepods dropped i n September to approximately h a l f the maximum August c o n c e n t r a t i o n ( f i g u r e 40). T h i s d e c l i n e i n numbers a l s o occurred i n September 1986 and was c o n s i d e r e d a s i g n i f i c a n t decrease at p=0.07 ( t a b l e 19). However, t h i s may be c o i n c i d e n t a l ; few r e p l i c a t e s were c o l l e c t e d , a d i f f e r e n t SCOR net was used i n August 1985, and t o t a l numbers of CVs i n c r e a s e d again i n October and November. Less than one copepod n r 3 was captured i n the upper 150 m in October. In November, the upper 100 m was sampled i n an attempt to determine the deepest depth at which N. plumchrus c o u l d not be found. No copepods were c o l l e c t e d i n the November 0-100 m sample but i n December, 0.2 n r 3 were captured i n the top 100 m. In December, the t o t a l number of copepods had decreased and they were showing s i g n s of maturation ( f i g u r e 40). Samples c o l l e c t e d i n January and February c o n t a i n e d h e a l t h y a d u l t s , many of which were v i s i b l y r e p r o d u c t i v e ( t a b l e 13). Some a d u l t females c o l l e c t e d i n March c o n t a i n e d v i s i b l e o v i d u c t s but many 37 were spent and perhaps dead upon c a p t u r e . The steady d e c l i n e in the o v e r w i n t e r i n g p o p u l a t i o n from December to March was probably due to death of a d u l t s as they completed t h e i r r e p r o d u c t i v e phase. The d i f f e r e n c e between the d e n s i t y of the reproducing p o p u l a t i o n and the CVs o v e r w i n t e r i n g at depth i n the f a l l was obvious and t h e r e f o r e i t was not necessary to t e s t mean d i f f e r e n c e s with an a n a l y s i s of v a r i a n c e . N a u p l i i and j u v e n i l e copepodites most l i k e l y a r r i v e d i n the s u r f a c e l a y e r s s t a r t i n g i n February and March s i n c e the occurrence of CIVs appeared d u r i n g the f o l l o w i n g month. A comparison of t o t a l numbers of N. plumchrus i n the s p r i n g and summer of 1986 ( A p r i l to J u l y ) to the preceding f a l l (August to November 1985), d i d not demonstrate a s i g n i f i c a n t d i f f e r e n c e between seasons ( t a b l e 18). The f a l l samples were p r i m a r i l y c o l l e c t e d from s t a t i o n G1748 r a t h e r than G1545 so perhaps the season e f f e c t was overshadowed by a s t a t i o n e f f e c t . The mean p o p u l a t i o n between months was s i g n i f i c a n t l y d i f f e r e n t . In A p r i l 1986, the r i s i n g p o p u l a t i o n was predominated by CIVs p r i m a r i l y occupying the upper 80 m at G1545 ( f i g u r e 39; t a b l e 15). The c o n c e n t r a t i o n of copepods v a r i e d g r e a t l y among r e p l i c a t e s as i n d i c a t e d by the 83% c o e f f i c i e n t of v a r i a t i o n and the broad 80% confidence i n t e r v a l ( t a b l e 14). Some CIVs, CVs, and CVIs were found between 80 and 250 m and below. Of the few copepods captured i n the s i n g l e haul from 250 m to the bottom, one was an a d u l t female which s t i l l c o n t ained eggs and muscle t i s s u e ( t a b l e 15). An unexpected d e c l i n e i n the t o t a l number of copepods o c c u r r e d i n May 1986. Eighty-seven percent of the t o t a l copepods 38 were c o l l e c t e d i n the top 80 m ( f i g u r e 39). A small percentage of the copepods were CIVs i n c o n t r a s t to the pr e v i o u s month. In the deepest zone they were a l l CVs with the exception of one a d u l t female. The c o n c e n t r a t i o n of N. plumchrus found i n June surpassed the numbers c o l l e c t e d i n May. Only CVs were present i n June samples with the m a j o r i t y occuping depths below 200 m with maximum c o n c e n t r a t i o n s of 80.6 n r 3 s i t u a t e d i n the bottom 95 m. Con c e n t r a t i o n s averaging 10.0 n r 3 s t i l l e x i s t e d i n the upper 80 m ( f i g u r e 39). The annual maximum was reached i n J u l y 1986. N. plumchrus was v i r t u a l l y absent from the top 150 m. C o n c e n t r a t i o n s i n c r e a s e d between 150-250 m but maximum c o n c e n t r a t i o n s of CVs averaging 125.2 i r r 3 , were found i n deep water. Copepod numbers d e c l i n e d somewhat i n August to l e v e l s comparable to the previous year. D e s p i t e the apparent decrease from the J u l y average the 80% conf i d e n c e i n t e r v a l c a l c u l a t e d f o r the August samples f e l l w i t h i n the range of the J u l y r e p l i c a t e samples which were much broader ( t a b l e 14). As mentioned the t o t a l number of copepods d e c l i n e d i n September ( t a b l e 19). 4.2.2. S a t e l l i t e Channel S a t e l l i t e Channel r e c e i v e s water from Haro S t r a i t to the southeast, S t u a r t Channel to the northwest, and Saanich I n l e t to the south ( f i g u r e 1). Copepods t r a n s p o r t e d i n t o or out of Saanich I n l e t must pass through t h i s channel. N. plumchrus CIVs and CVs were captured at the 75 m S a t e l l i t e s t a t i o n only i n May 39 1985, and, A p r i l and May 1986, with g r e a t e r numbers o c c u r r i n g i n 1985 ( f i g u r e 41). Copepods captured i n S a t e l l i t e Channel dur i n g ebb t i d e are co n s i d e r e d as emigrants and those caught d u r i n g f l o o d t i d e are assumed t o be immigrants. The samples c o l l e c t e d i n May 1985 and 1986 c o i n c i d e d with the ebb t i d e whereas those c o l l e c t e d i n A p r i l 1986 were caught d u r i n g the f l o o d t i d e . To determine whether these numbers represented a net gain or l o s s of copepods to the i n l e t , i t would have been necessary to sample d u r i n g each t i d a l c y c l e . Since t h i s was not p o s s i b l e , the hig h c o n c e n t r a t i o n of N. plumchrus found i n May 1985 samples can not be c o n s i d e r e d an i n d i c a t i o n of a higher p o p u l a t i o n i n 1985. 4.2.3. Saanich I n l e t Both v e r t i c a l and h o r i z o n t a l samples were c o l l e c t e d i n Saanich I n l e t . Three s t a t i o n s were t y p i c a l l y sampled Saa9 ( n o r t h ) , Saa3 ( c e n t r a l ) , and Saa0.8 (south; f i g u r e 5). The c e n t r a l s t a t i o n , Saa3, was the only Saanich s t a t i o n that was sampled i n the f i r s t few months of the program (from May through to August, 1985). The p o p u l a t i o n present at t h i s s t a t i o n d u r i n g the summer of 1985 appeared to be higher than i n 1986. The e f f e c t s of year and month on the abundance of N. plumchrus at s t a t i o n Saa3 (May, J u l y , and August, 1985 and 1986) were not s i g n i f i c a n t at the 5% l e v e l ( t a b l e 20). However, at the 10% l e v e l (p=0.09) the p o p u l a t i o n i n 1985 can be c o n s i d e r e d s i g n i f i c a n t l y higher than i n 1986. T h i s may be due to an i n c r e a s e d acceptance of water.passing through the SCOR net used 40 from May to August 1985 although dense c o n c e n t r a t i o n s were a l s o captured with Clarke-Bumpus nets i n 1985. The d i s t r i b u t i o n of N. plumchrus i n the summer of 1985 i n d i c a t e d that the CVs were showing m i g r a t i o n a l p a t t e r n s c h a r a c t e r i s t i c of t h i s s p e c i e s i n the S t r a i t of Georgia except that they tended to aggregate at shallower depths. In May 1985, h o r i z o n t a l hauls r e v e a l e d that of the depths sampled, maximum numbers of 33.3 i r r 3 were found at 150 m ( t a b l e 16). An e x t r a p o l a t i o n of the oxygen data a v a i l a b l e f o r s t a t i o n s Saa9 and Saa0.8 at 140 m i n d i c a t e d t h at the oxygen content of the water at Saa3 was probably between 0.0 and 0.70 mL L " 1 . At depths of 5 and 50 m some CIVs were present but only CVs were captured below these depths. V e r t i c a l hauls demonstrated that both CIVs and CVs were present i n the upper 120 m most of which were CVs ( f i g u r e 43). In J u l y 1985, the v e r t i c a l haul samples c o n t a i n e d c o n c e n t r a t i o n s of 7.2 CVs n r 3 i n the top 150 m. U n f o r t u n a t e l y , the haul from the bottom of the water column was not s u c c e s s f u l . However, the h o r i z o n t a l hauls i n d i c a t e d that most of the copepods c o l l e c t e d i n the 0-150 m v e r t i c a l h a u l , were s i t u a t e d around 150 meters. Samples from 50, 100, and 120 m d i d not c o n t a i n any CVs, but, c o n c e n t r a t i o n s of 75.6 i r r 3 were found at 150 m ( t a b l e 16). Ten d i s c r e t e depths between 110 and 190 m were sampled with C-B nets at Saa3 i n August 1985. The hi g h e s t d e n s i t y of CVs (6.0 i r r 3 ) , was found at 160 m ( t a b l e 16 & f i g u r e 17). Oxygen c o n c e n t r a t i o n s of 0.11 mL L" 1 were present at 165 m, and they decreased to 0.02 mL L" 1 at 185 m ( f i g u r e 17). No copepods were 41 captured from 170, 180, and 190 m. Sampling at Saa9 and Saa0.8 commenced i n September 1985. Very few copepods were captured at any of the three Saanich s t a t i o n s f o l l o w i n g the deep water renewal. Based on copepod numbers found at Saa3 i n p r e v i o u s months, higher numbers were expected to have been found. Copepod c o n c e n t r a t i o n s of 0.1 i r r 3 were captured i n the bottom 90 m a t Saa3 and none were found at Saa0.8 ( f i g u r e 43 & 44). A t o t a l of 0.2 n r 3 were c o l l e c t e d at Saa9, however, not a s i n g l e CV or a d u l t was found at s t a t i o n Saa9 from October to February ( f i g u r e 45; t a b l e 13 & 15). At s t a t i o n s Saa3 and Saa0.8, N. plumchrus was o c c a s i o n a l l y captured d u r i n g the winter months ( f i g u r e 43 & 44). The t o t a l number of copepods d i d not exceed 0.2 nr 3 at e i t h e r s t a t i o n . The specimens d i d not show s i g n s of sexual maturation u n t i l January 1986. Of the few specimens (0.2 n r 3 ) captured at s t a t i o n Saa0.8 and Saa3 one s e x u a l l y mature female was found at each s t a t i o n ( t a b l e 15). An a d u l t female copepod was captured again i n March at Saa3 and one a d u l t male was captured i n A p r i l at Saa0.8. Low numbers of CIVs and CVs began to appear i n A p r i l 1986 at s t a t i o n s Saa9, Saa3, and Saa0.8 ( f i g u r e 41; t a b l e 15). Stage IV and V copepodites c o l l e c t e d i n A p r i l 1986 were l o c a t e d w i t h i n the top 80 m. H o r i z o n t a l tows at Saa0.8 i n d i c a t e d that at l e a s t some of the CIVs were present at shallow depths of 5 m ( t a b l e 17) . Copepod numbers i n c r e a s e d i n May 1986 at a l l three Saanich s t a t i o n s . C o n c e n t r a t i o n s remained the highest at Saa9 (1.4 n r 3 ) and lowest at Saa0.8 (0.2 n r 3 ; f i g u r e 41). Intermediate c o n c e n t r a t i o n s were present at Saa3. Both CIVs and CVs, were 42 p r i m a r i l y l o c a t e d i n the upper 80 m ( f i g u r e 43). In June 1986, only CVs were pres e n t . The c o n c e n t r a t i o n of copepods d i d not i n c r e a s e at any of the three s t a t i o n s but they had changed i n t h e i r v e r t i c a l d i s t r i b u t i o n . Approximately 20% of the copepods at s t a t i o n Saa3 and Saa9 were found i n the top 120 m ( f i g u r e 43 & 45). At s t a t i o n G1545 some CVs were a l s o found i n the upper r e g i o n of the water column. There were s t i l l very few copepods at Saa0.8, h o r i z o n t a l hauls i n d i c a t e d that some CVs were present at 90 and 110 m depths, above oxygen c o n c e n t r a t i o n s of 0.37 mL L" 1 ( f i g u r e 46). The h i g h e s t d e n s i t y of N. plumchrus found i n 1986 was l o c a t e d at Saa9 i n J u l y where maximum c o n c e n t r a t i o n s of 7.1 n r 3 , o c c u r r e d below 80 m ( f i g u r e 45). A l l of the copepods at Saa3 were a l s o at o v e r w i n t e r i n g depths. The CVs c o l l e c t e d at Saa0.8 were present between 100 and 170 m (the mid depth) where d i s s o l v e d oxygen l e v e l s were 1.23 and 0.10 mL L" 1 ( t a b l e 10). Below 180 m the oxygen decreased to 0.07 mL L ~ 1 . D e s p i t e the obvious d i f f e r e n c e between the s i z e of the N. plumchrus p o p u l a t i o n i n the S t r a i t of Georgia and Saanich I n l e t , the two regions were compared i n May, June, and J u l y 1986 i n an attempt to d e t e c t any trends between the months. The S t r a i t of Georgia was suspected to be the primary source of N. plumchrus i n 1986 s i n c e the o v e r w i n t e r i n g p o p u l a t i o n i n Saanich I n l e t was n e g l i g i b l e i n 1985/1986. An a n a l y s i s of v a r i a n c e between Saa9 and G1545 ( s t a t i o n x month) i n d i c a t e d a s i g n i f i c a n t d i f f e r e n c e between the s t a t i o n s (p=0.00l) and the months (p=0.02)(table 25). The two homogeneous subsets among the months, d e t e c t e d with the S c h e f f e , B o n f e r r o n i , and minimal t e s t s 43 demonstrated s i m i l a r i t i e s between May and June, and June and J u l y ( t a b l e 25), At G1545 the copepods had i n c r e a s e d i n abundance from May to J u l y , whereas, the numbers at Saa9 were steady i n May and June and then i n c r e a s e d i n J u l y . A comparison of Saa0.8 and G1545 (May to J u l y ) d i d not demonstrate a s i g n i f i c a n t d i f f e r e n c e between the months ( t a b l e 26). A s e r i e s of r e p l i c a t e h o r i z o n t a l tows was taken i n J u l y at s t a t i o n Saa9. A s i n g l e f a c t o r ANOVA was used to t e s t the h o r i z o n t a l haul samples f o r a s i g n i f i c a n t d i f f e r e n c e of the abundance of N. plumchrus at four depths (135,140,145, and 150 m; t a b l e 17). The mean c o n c e n t r a t i o n s among depths were s i g n i f i c a n t l y d i f f e r e n t at the 5% l e v e l ( t a b l e 27). Note that one r e p l i c a t e value of zero was not i n c l u d e d i n the 135 and 150 m data s e t s because the volume of water f i l t e r e d was n e g l i g i b l e ( i . e . <0.2 m3; t a b l e 17 & 27). Based on these r e s u l t s , the hypothesis that the means are equal has been r e j e c t e d and t h e r e f o r e c o n c e n t r a t i o n s of copepods at 140 and 145 m are c o n s i d e r e d s i g n i f i c a n t l y g r e a t e r than c o n c e n t r a t i o n s above and below t h i s r e g i o n . The d i s s o l v e d oxygen content at 140 m was 0.20 mL L" 1 although the oxygen was measured 1.5 days p r i o r to the c o l l e c t i o n of copepods and may have changed s l i g h t l y . During August 1986 sampling very few copepods were found at s t a t i o n Saa9, (<0.5 n r 3 ; t a b l e 15). The i n c r e a s e i n d i s s o l v e d oxygen at 140 m suggested that some water movement had o c c u r r e d i n August a t Saa9. P o p u l a t i o n numbers were s t i l l low at Saa0.8 (<0.1 n r 3 ) but had reached a maximum at Saa3. However, the p o p u l a t i o n d i f f e r e n c e s between May, June and August were not s i g n i f i c a n t at Saa3. 44 The m a j o r i t y of copepods at Saa3 were below 170 m as i n d i c a t e d by both v e r t i c a l and h o r i z o n t a l samples ( f i g u r e 43). The h i g h e s t c o n c e n t r a t i o n s of CVs were present at 170 and 180 m ( f i g u r e 18). The water at 170 m c o n t a i n e d 0.31 mL 0 2 L~ 1 f o l l o w e d by an i n c r e a s e i n d i s s o l v e d oxygen below t h i s depth. The presence of an oxygen minimum at 170 m may be an i n d i c a t i o n that a small amount of dense water i n t r u d e d i n e a r l y August. No specimens were c o l l e c t e d at 190 m due to the low volume of water f i l t e r e d at t h i s depth ( t a b l e 17). The v a r i a n c e was analysed between the three Saanich I n l e t s t a t i o n s f o r the months of A p r i l to August 1986. The n u l l h y p o t hesis in which the mean abundance of N. plumchrus was equal at each s t a t i o n over the months t e s t e d , was r e j e c t e d at p=0.07 ( t a b l e 21). The p o p u l a t i o n l e v e l s at Saa0.8 were suspected to be l e a s t s i m i l a r to s t a t i o n s Saa3 and Saa9 s i n c e i t was the f u r t h e s t s t a t i o n from the mouth of the i n l e t . Each s t a t i o n was t e s t e d a g a i n s t Saa0.8 s e p a r a t e l y to determine i f the d i f f e r e n c e between the s t a t i o n s was g r e a t e r i n e i t h e r case. The d i f f e r e n c e between s t a t i o n s Saa9 and Saa0.8, and, Saa3 and Saa0.8 were s i m i l a r ( t a b l e 22 & 23). For both comparisons the s t a t i o n s were separated i n t o two homogeneous subsets at the 10% l e v e l , r e a f f i r m i n g that the p o p u l a t i o n numbers at Saa0.8 were s i g n i f i c a n t l y lower. The l a c k of r e p l i c a t i o n at s t a t i o n Saa3 and e s p e c i a l l y Saa9, weakened the ANOVA t e s t s . A d i f f e r e n c e between the months, was not d e t e c t e d among Saanich s t a t i o n s and, as expected, there was not a s i g n i f i c a n t d i f f e r e n c e between s t a t i o n s Saa3 and Saa9 ( t a b l e 24). In .each a n a l y s i s the f a c t o r s were t e s t e d f o r 45 homogeneity of v a r i a n c e , using the B a r t l e t t c h i - s q u a r e t e s t . The n u l l h y p o thesis was r e j e c t e d at the 5% l e v e l f o r the t e s t between s t a t i o n s Saa3 and Saa0.8 ( t a b l e 23). However, the use of t h i s t e s t was l i m i t e d s i n c e r e p l i c a t e samples were not a v a i l a b l e f o r s t a t i o n s Saa9 and Saa3 (with the e x c e p t i o n of August, 1986 at Saa3). During September the h i g h e s t copepod d e n s i t y (0.2 m"3) was present at the southernmost s t a t i o n , Saa0.8 ( t a b l e 15). Specimens at s t a t i o n s Saa3 and Saa9 (<0.2 n r 3 ) were l o c a t e d below 100 m. At Saa0.8, 67% of a l l specimens were present above the oxygen minimum and the remaining 33% (0.27 nr 3) were captured below t h i s zone ( f i g u r e 44). The c o n c e n t r a t i o n of oxygen i n the minimum zone ranged between 0 and 0.16 mL L " 1 as a r e s u l t of the displacement of low oxygen bottom water dur i n g the deep water renewal (table- 10). 4.2.4. Se c h e l t I n l e t The numbers c o l l e c t e d i n November 1985 and February 1986 i n d i c a t e d that a much l a r g e r o v e r w i n t e r i n g p o p u l a t i o n i n h a b i t e d S e c h e l t I n l e t than Saanich I n l e t ( f i g u r e 48; t a b l e 13 & 15). During November, c o n c e n t r a t i o n s of 16.9 n r 3 were found between 100-245 m at Sc1 i n c o n t r a s t to the few copepods found i n Saanich I n l e t throughout the w i n t e r . In February, the number of a d u l t s had decreased to 2 n r 3 between 80 and 245 m, presumably due to t h e i r d e c l i n e a f t e r r e p r o d u c t i o n . The numbers c o l l e c t e d i n August 1986 v a r i e d c o n s i d e r a b l y among the three s t a t i o n s sampled ( f i g u r e 48 & 49). The h i g h e s t 46 number of CVs (32.2 n r 3 ) were found at Sc1a ( f i g u r e 48). D i s r e g a r d i n g the depth range sampled, the t o t a l number per c u b i c meter c o l l e c t e d at Sc1a was s t i l l much higher than e i t h e r Sc2a, or Sc2. 4.3. A n a l y s i s of Experimental Data L i v e specimens of Neocalanus plumchrus were c o l l e c t e d with the i n t e n t i o n of examining the s u r v i v a l of t h i s s p e c i e s under d i f f e r e n t oxygen c o n c e n t r a t i o n s . Many qu e s t i o n s arose while observing the copepods i n c a p t i v i t y and during e x p e r i m e n t a t i o n . Although, a l o t of time c o u l d not be d e d i c a t e d to a d d r e s s i n g these q u e s t i o n s , a few p r e l i m i n a r y t e s t s were conducted on f a e c a l p e l l e t p r o d u c t i o n and the m o r t a l i t y r a t e of fed versus s t a r v e d copepods. 4.3.1. Observations of Fed and Starved Copepods The CVs c o l l e c t e d from May through to November of 1986 were fed phytoplankton with the exc e p t i o n of some October copepods which were s t a r v e d f o r o b s e r v a t i o n a l purposes and June 1987 copepods which were only h e l d i n c a p t i v i t y f o r 8 days. I n g e s t i o n of food by the copepods was v e r i f i e d by an i n s p e c t i o n of the d e b r i s i n the f l a s k s f o r the presence of f a e c a l p e l l e t s . The number of f a e c a l p e l l e t s was counted on one occasion i n which two groups of 30 copepods from September and October c o l l e c t i o n s , were fed equal q u a n t i t i e s of phytoplankton. A f t e r 12 hours a t o t a l of 29 f a e c a l p e l l e t s were c o l l e c t e d , 83% of 47 which were from the September thermos ( t a b l e 28). The number of copepod deaths d u r i n g c a p t i v i t y f o r both fed and s t a r v e d October specimens, was recorded over a p e r i o d of two months ( f i g u r e 50). Each thermos c o n t a i n e d 30 copepods at the beginning of the r e c o r d i n g p e r i o d . Copepods c o l l e c t e d i n October which were not fed d i e d i n c a p t i v i t y at a r a t e of 2.05 week - 1. F i g u r e 50 shows a f a i r l y constant i n c r e a s e i n the number of copepods dying i n the s t a r v e d group f o l l o w e d by what appeared to be a sharp r i s e i n t h e i r m o r t a l i t y a f t e r the 55th day. In c o n t r a s t , the October specimens which were fed d i e d at a r a t e of 0.34 copepods•week" 1. The number of dead copepods a f t e r the 12th day remained unchanged u n t i l the 62nd day at which time a two more d i e d ( f i g u r e 50). 4.3.2. Oxygen Tolerance T e s t s Three of the i n i t i a l low oxygen t o l e r a n c e experiments were run f o r a p e r i o d of 24 and 21 hours ( t a b l e 5). At low oxygen l e v e l s (0.45 mL L" 1) i n experiment #1, a l l copepods d i e d d u r i n g the 24 hour p e r i o d ( t a b l e 5 ) . At higher mean oxygen c o n c e n t r a t i o n s (0.83, 0.60 mL L" 1) 80 and 90% of the copepods d i e d . Seventy-three percent of the copepods d i e d when su b j e c t e d to 0.91 mL L " 1 f o r 21 hours. The number of days spent i n c a p t i v i t y at the time of experimentation ranged from 12 days i n experiment #1, to 45 days i n experiment #4 ( t a b l e 5). The m o r t a l i t y i n the c o n t r o l s was 0% i n a l l cases except experiment #4 i n which 10% d i e d ( t a b l e 5). The r e s u l t s of the 12 hour experiments were v a r i a b l e . The 48 t h i r t e e n experiments were conducted on CVs c o l l e c t e d i n the S t r a i t of Georgia with the exception of two oxygen t e s t s run on CVs c o l l e c t e d from Saanich I n l e t i n J u l y 1986. At both h i g h and low oxygen c o n c e n t r a t i o n s (0.46 to 2.11 mL L ~ 1 ) , m o r t a l i t i e s higher than 70% were recorded ( f i g u r e 51). Likew i s e , the percent m o r t a l i t y was 12% f o r oxygen t e s t s i n the lower range (0.56 mL L" 1) and 0% f o r oxygen l e v e l s of 0.95 mL L" 1 ( f i g u r e 51). The v a r i a b i l i t y i n the r e s u l t s may be due to the l e n g t h of c a p t i v i t y ( f i g u r e 52). F i g u r e 52 i n d i c a t e s that the m o r t a l i t y of the copepods i n c r e a s e d as the p e r i o d of c a p t i v i t y i n c r e a s e d . Copepods were 3 to 103 days i n c a p t i v i t y b efore they were used i n the experiments ( t a b l e 5). The l a s t three experiments were conducted on specimens c o l l e c t e d i n June 1987 and were t e s t e d w i t h i n 3 to 8 days of c o l l e c t i o n . These experiments were run at oxygen l e v e l s that were p r e v i o u s l y t e s t e d yet they r e s u l t e d i n lower m o r t a l i t i e s , s upporting the hypothesis that the number of days i n c a p t i v i t y i n f l u e n c e d the outcome of the experiments ( f i g u r e 51). I t i s important to note that i n experiment #13, 50% of the copepods c o l l e c t e d from the S t r a i t d i e d i n water c o n t a i n i n g 0.47 mL 0 2 L " 1 , y e t , i n Saanich I n l e t , CVs were c o l l e c t e d i n J u l y 1986 from a depth where the oxygen content was 0.20 mL L" 1 ( f i g u r e 47). The Saanich I n l e t specimens t e s t e d at 0.56 and 0.54 mL L" 1 had the lowest m o r t a l i t y f o r the time p e r i o d that they were h e l d in c a p t i v i t y ( f i g u r e 52). O v e r a l l , the lowest oxygen c o n c e n t r a t i o n s were expected to r e s u l t i n the hi g h e s t m o r t a l i t y , with- a p r o g r e s s i v e i n c r e a s e i n the number dying as the p e r i o d of 49 c a p t i v i t y i n c r e a s e d ( f i g u r e 53). The r e s u l t s suggest that d i f f e r e n c e s i n the time of year (May-November) and the region i n which the CVs were captured ( i . e . Saanich I n l e t versus the S t r a i t of Georgia) may have a l s o i n f l u e n c e d the outcome of the experiments. In l a t e November the CVs s t a r t e d to moult i n t o a d u l t s and may have a f f e c t e d the r e s u l t s of experiments 8, 9 and 10 ( t a b l e 5 & f i g u r e 52). C o n t r o l experiments were run at oxygen c o n c e n t r a t i o n s of 4.20 to 6.90 mL L " 1 . The s u r v i v a l r a t e of the copepods was 100% in most of the 12 hour experiments with the ex c e p t i o n of three c o n t r o l f u n n e l s i n which 10, 20 and 30% of the copepods had d i e d ( f i g u r e 51). The d u r a t i o n of c a p t i v i t y p r i o r to these experiments ranged from 31 to 57 days. 4.4. Sediment Trap Samples Sediment t r a p samples were examined from March to November 1985 and from June to September 1986. In 1985, n e i t h e r whole specimens, or p i e c e s of N. plumchrus were recovered from samples c o l l e c t e d at s t a t i o n Saa9. At Saa0.8, a t o t a l of three CVs were c o l l e c t e d i n the mid and deep water sediment t r a p s . The two specimens found i n the samples from 135 m were c o l l e c t e d from tr a p s set out between May 21 and J u l y 3 1985. One other copepod was c o l l e c t e d i n the 180 m t r a p between August 7 and September 17th 1985. N. plumchrus was not found i n the sediment t r a p samples c o l l e c t e d i n June through September 1986. The water at a depth of 140 m, next to the depth where the dead copepods were c o l l e c t e d i n J u l y 1985, c o n t a i n e d 0.06 mL 0 2 50 L" 1 i n May and 0.20 mL 0 2 L~ 1 i n J u l y . In August the bottom 50 m was devoid of oxygen but i n September, the oxygen c o n c e n t r a t i o n at the depth of the sediment t r a p was 0.41 mL L " 1 . Above t h i s depth oxygen c o n c e n t r a t i o n s were <0.10 mL L" 1 at 120 and 140 m due to the displacement of low oxygen water d u r i n g the deep water renewal. I t i s p o s s i b l e that the low oxygen c o n d i t i o n s caused the death of the copepods although the numbers do not i n d i c a t e any a p p r e c i a b l e m o r t a l i t y . A few o b s e r v a t i o n s i n the l a b o r a t o r y , on the f a t e of t h i s s p e c i e s a f t e r death suggests that only a small p r o p o r t i o n of the copepods would s e t t l e i n t o the t r a p s and remain t h e r e . F o l l o w i n g the low oxygen t o l e r a n c e experiment #8, ten dead copepods were p l a c e d i n a beaker f o r a p e r i o d of 24 days ( t a b l e 29). A f t e r 2.5 days a l l ten copepods were at the bottom of the beaker. As t h e i r t i s s u e s were decomposed by micro-organisms they g r a d u a l l y were resuspended i n the water column. In f i v e days, four copepods were f l o a t i n g at the s u r f a c e and on the e i g h t h day a t o t a l of s i x copepods had f l o a t e d to the s u r f a c e . For the f o l l o w i n g 16 days there was no change, the remaining four copepods d i d not f l o a t to the s u r f a c e . The copepods which d i e d d u r i n g experiment #9 were a l s o i s o l a t e d and observed a f t e r t h e i r death. Of the 20 dead copepods, seven had f l o a t e d to the s u r f a c e a f t e r four days ( t a b l e 29). The number of copepods f l o a t i n g at the s u r f a c e i n c r e a s e d up to the e l e v e n t h day at which time a t o t a l of 15 copepods had f l o a t e d to the s u r f a c e and only f i v e remained at the bottom of the beaker. L i p i d s from the specimens had c o l l e c t e d at the s u r f a c e , forming white d r o p l e t s of wax-like 51 m a t e r i a l . Based on these p r e l i m i n a r y o b s e r v a t i o n s , i t i s p o s s i b l e that 60 to 75% of copepods which may d i e due to unfavourable c o n d i t i o n s i n Saanich I n l e t , would not be c o l l e c t e d i n the sediment t r a p s because of resuspension a f t e r 4-11 days. The percentage of copepods l o s t due to resuspension would depend on the depth at which they d i e d r e l a t i v e to the depth of the t r a p , and on the e f f e c t i v e n e s s of the NaN 3 (sodium azide) p r e s e r v a t i v e . The tr a p s c o n t a i n i n g b r i n e without sodium a z i d e would have been l e s s l i k e l y to r e t a i n specimens of N. plumchrus• Once a l l of the t i s s u e s had been decomposed, the exoskeleton would have sunk but the l i k e l i h o o d of r e d i s p e r s a l would have been much g r e a t e r . 52 5. DISCUSSION The o b j e c t i v e of t h i s study was to determine i f Neocalanus  plumchrus had a r e s i d e n t p o p u l a t i o n i n Saanich I n l e t d u r i n g 1985 and 1986, and i f not, the f a c t o r s that prevented t h i s s p e c i e s from becoming e s t a b l i s h e d i n the i n l e t . H a r r i s o n et a l . (1983) s t a t e d that there i s a l a c k of an o v e r w i n t e r i n g p o p u l a t i o n of N. plumchrus in Saanich I n l e t as a r e s u l t of the depth d i f f e r e n c e between the f j o r d and the S t r a i t of Georgia. On the other hand, s u b s t a n t i a l p o p u l a t i o n s of N. plumchrus were found i n Saanich I n l e t d u r i n g the winter i n October 1969 (Hoos, 1970) and December 1974 (Cowen, 1982). The h y p o t h e s i s t e s t e d was that the p h y s i c a l and chemical c h a r a c t e r i c s of Saanich I n l e t , i n f l u e n c e the d i s t r i b u t i o n and abundance of N. plumchrus d u r i n g t h e i r ontogenetic m i g r a t i o n and are r e s p o n s i b l e f o r the eventual l o s s of the o v e r w i n t e r i n g p o p u l a t i o n d u r i n g some ye a r s . Other p o s s i b l e causes f o r the r e d u c t i o n i n N. plumchrus are d i s c u s s e d with r e f e r e n c e to sediment t r a p data and the r e s u l t s of low oxygen experiments. 5.1. P h y s i c a l i n f l u e n c e s on the Neocalanus plumchrus p o p u l a t i o n i n Saanich I n l e t The d i s t r i b u t i o n of N. plumchrus, as determined by v e r t i c a l and h o r i z o n t a l plankton h a u l s , was compared with the p h y s i c a l hydrographic f e a t u r e s of Saanich I n l e t . The abundance of t h i s s p e c i e s was compared to i t s p o p u l a t i o n i n the S t r a i t of Georgia where i t i s known to be a predominant member of the zooplankton assemblage (LeBrasseur et a l . , 1969; Gardner, 1977; H a r r i s o n et 53 a l . , 1983). The Saanich r e s u l t s were a l s o compared with the d i s t r i b u t i o n of the s p e c i e s i n Sechelt I n l e t where the depth i s s i m i l a r to Saanich I n l e t but the p h y s i c a l and chemical c o n d i t i o n s d i f f e r . An o v e r w i n t e r i n g p o p u l a t i o n of N. plumchrus was indeed l a c k i n g i n Saanich I n l e t from September 1985 through March 1986. Very few copepods (<0.4 n r 3 ) were captured at any of the three s t a t i o n s d u r i n g t h i s time yet higher d e n s i t i e s had been found at Saa3 p r i o r to the onset of f a l l . During the l a t t e r p a r t of May 1985, copepodite stages 4 and 5 (CIVs and CVs) were found i n f a i r l y high c o n c e n t r a t i o n s (15.0 n r 3 ) i n the top 15 m and h o r i z o n t a l haul samples demonstrated a l a y e r of CVs (33.3 n r 3 ) at 150 m ( f i g u r e 43 & t a b l e 16). Samples from the S a t e l l i t e Channel s t a t i o n (Sate) taken during an ebb t i d e i n May, showed that CIVs and CVs were being t r a n s p o r t e d out of the i n l e t ; i t i s probable that the copepods were a l s o being c a r r i e d i n t o the i n l e t d u r i n g f l o o d t i d e ( f i g u r e 42). The d e n s i t y of CVs at 150 m i n J u l y (75.6 n r 3 ) was comparable to d e n s i t i e s found at o v e r w i n t e r i n g depths i n the S t r a i t of Georgia i n August ( i n J u l y , s t a t i o n G1748 was not sampled to the bottom; f i g u r e 47 & 39). Although, i n Saanich I n l e t the CVs were conc e n t r a t e d i n a band over a very narrow depth range ( 1 50-160 m) . H o r i z o n t a l samples c o l l e c t e d i n August d e t e c t e d a maximum c o n c e n t r a t i o n of CVs at 160 m (6.0 n r 3 ) a much lower c o n c e n t r a t i o n than i n J u l y ( t a b l e 16). The d e c l i n e i n numbers i n August may be a t t r i b u t e d to 1) a s h i f t i n the d i s t r i b u t i o n of the dense l a y e r of copepods, e i t h e r v e r t i c a l l y or l a t e r a l l y , or 2) some of the CVs may have d i e d due to adverse 54 c o n d i t i o n s or 3) p r e d a t i o n . The data c o l l e c t e d i n the summer of 1985 i n d i c a t e d that N. plumchrus was present i n the i n l e t at d e n s i t i e s s u f f i c i e n t to e s t a b l i s h a p o p u l a t i o n . In the l a t t e r p art of the summer the copepods had migrated to o v e r w i n t e r i n g depths, w e l l below the s i l l (75 m), so that the copepods were expected to be 'locked' i n the i n l e t . However, as i n d i c a t e d by samples c o l l e c t e d at a l l three Saanich I n l e t s t a t i o n s , the p o p u l a t i o n of N. plumchrus had almost completely disappeared from the i n l e t by September ( t a b l e 13) . The appearance of dense oxygenated water i n t r u d i n g i n t o the bottom waters of Saanich I n l e t i n September, c o i n c i d e d with the o b s e r v a t i o n that few CVs were l e f t to overwinter i n the i n l e t . The oxygen p r o f i l e d u r i n g the deep water renewal showed a d i s t i n c t displacement of oxygen poor water at Saa9 and Saa0.8 ( f i g u r e 12 & 22). In f a c t , the minimum oxygen v a l u e s at Saa9 i n September and October were lower than p r e v i o u s l y recorded oxygen valu e s at t h i s s t a t i o n ( t a b l e 16), suggesting that the water may have o r i g i n a t e d from the d i r e c t i o n of s t a t i o n SaaO.8 and be i n t r a n s i t out of the i n l e t . I suggest that at l e a s t p a r t of the N. plumchrus p o p u l a t i o n was c o n t a i n e d i n the water that was d i s p l a c e d and f o r c e d out of the i n l e t d u r i n g the e a r l y stages of the deep water renewal i n 1985. The f o l l o w i n g i s a h y p o t h e t i c a l case to e x p l a i n how N. plumchrus may have been t r a n s p o r t e d out of the i n l e t , u s i n g s u p p o r t i n g data from the study. F i r s t of a l l , i t w i l l be assumed that N. plumchrus can not t o l e r a t e oxygen l e v e l s < 0.20 mL L" 1 based on the d i s t r i b u t i o n of N. plumchrus i n August 1985 and 55 J u l y 1986 ( f i g u r e 17 & 47). In a d d i t i o n , other crustacean s p e c i e s , i n c l u d i n g c a l a n o i d copepods, do not tend to be found at depths c o n t a i n i n g < 0.20 mL L~ 1 (Longhurst, 1967; C h i l d r e s s , 1975; Raymont, 1983; A l l d r e d g e et a l . , 1984). Secondly, the CVs w i l l be presumed to migrate to depths which correspond to the minimum oxygen l e v e l that they can t o l e r a t e ( f i g u r e 54). With r e f e r e n c e to the hydrographic data c o l l e c t e d i n August 1985, the maximum depth of m i g r a t i o n by the CVs would have been around 150-160 m at Saa9 and Saa3, and 100-120 m at Saa0.8 ( t a b l e 6 & 9). As the water c o n t a i n i n g < 0.20 mL L " 1 was d i s p l a c e d to a depth of 75 m at Saa9 and Saa0.8, and between 110 and 150 m at Saa0.8 ( f i g u r e 54), the copepods would 1) a v o i d t h i s low oxygen zone by m a i n t a i n i n g a depth above the oxygen minimum, 2) be d i s p l a c e d along with the water that they occupied, or 3) the copepods at s t a t i o n Saa9 would have been mixed with the incoming water. In August 1985 the c o n c e n t r a t i o n of CVs at 160 m (6.0 n r 3 ) and the lack of copepods below t h i s depth were an i n d i c a t i o n that they were a v o i d i n g the low oxygen (0.11 mL L~ 1) at 165 m ( f i g u r e 17). I f the d i s c r e t e zone of oxygen poor water at Saa0.8 was a l s o found throughout most of the i n l e t then the CVs were l i k e l y r e l o c a t i n g to depths between 75 and 100 m at Saa3. Once they were w i t h i n the range of the s i l l depth (75 m) they c o u l d have been c a r r i e d out of the i n l e t i n the o u t f l o w i n g water. The copepods found i n Saanich I n l e t d u r i n g the f a l l and winter of 1985-1986 were e i t h e r a r e s i d u a l p o p u l a t i o n l e f t over from the summer months or were t r a n s p o r t e d i n t o the i n l e t d u r i n g the o v e r w i n t e r i n g p e r i o d . The S t r a i t of Georgia data 5 6 demonstrated that a very small number of copepods (<0.2 i r r 3 ) were present i n the top 100. m throughout the winter. I f we co n s i d e r these data to be r e p r e s e n t a t i v e of the c e n t r a l r e g i o n of the S t r a i t of Georgia, then the copepods c o u l d have been t r a n s p o r t e d i n t o the i n l e t from the S t r a i t . A few specimens of N. plumchrus may a l s o have been t r a n s p o r t e d i n from Juan de Fuca S t r a i t . The o v e r w i n t e r i n g p o p u l a t i o n of N. plumchrus was sampled with a Bioness sampler (owned by I.O.S.) at Saa3 on March 5, 1986. A much gr e a t e r volume of water (208 m3) was sampled than was p o s s i b l e with e i t h e r the mSCOR net ( t a b l e 30), or the C-B nets ( t a b l e 17), yet only one specimen of N. plumchrus was captured (0.02 n r 3 ) between 100 and 150 m. T h i s supports the data c o l l e c t e d from September to March (1985-1986) u s i n g the mSCOR net. The important p o i n t i s that there probably was not a s u f f i c i e n t number of N. plumchrus i n Saanich I n l e t to reproduce i n s u b s t a n t i a l numbers from January to March 1986. As there were so few a d u l t s c o l l e c t e d from January to March (<0.20 n r 3 ) , the l i k e l i h o o d of encountering a copepod of the opp o s i t e sex d i d not appear h i g h . N. plumchrus was r e i n t r o d u c e d i n t o Saanich I n l e t i n the s p r i n g and summer of 1986. Within the f j o r d there was a c o n s i s t e n t l y higher c o n c e n t r a t i o n (p=0.07) of copepods at Saa9 and Saa3 than at Saa0.8 (from A p r i l to August; t a b l e 21). The s p a t i a l d i s t r i b u t i o n of N. plumchrus along the north-south a x i s of the i n l e t r e s u l t s from the m a j o r i t y of the Saanich p o p u l a t i o n o r i g i n a t i n g from o u t s i d e the i n l e t and c o n c e n t r a t i n g at the two s t a t i o n s c l o s e s t to the mouth (Saa3 and Saa9). The f a c t that 57 s t a t i o n Saa0.8 becomes more stagnant than e i t h e r Saa3 or Saa9 i s an i n d i c a t i o n that there i s l e s s of an exchange of water, and hence copepods, at t h i s s t a t i o n . The low numbers at Saa0.8 i s f u r t h e r evidence that r e p r o d u c t i o n of N. plumchrus was reduced or l a c k i n g i n the i n l e t . The CIVs and CVs were c o l l e c t e d at s t a t i o n Sate in A p r i l 1986 d u r i n g the f l o o d t i d e . In the f o l l o w i n g month, they were captured at Sate d u r i n g the ebb t i d e . The CIVs and CVs c o u l d have been t r a n s p o r t e d from the S t r a i t of Georgia i n t o Saanich I n l e t throughout the months of A p r i l , May, and June because they were s t i l l present i n the top 80 m at t h i s time ( f i g u r e 42). F u l t o n (1973) and Black (1984) have observed that N. plumchrus i s c o n c e n t r a t e d i n the c e n t r a l , deepest p o r t i o n of the S t r a i t of Georgia d u r i n g the o v e r w i n t e r i n g p e r i o d but the n a u p l i i and copepodites may be found i n high c o n c e n t r a t i o n s southwest of the c e n t r a l r e g i o n i n the s p r i n g and summer. Hence, some of the copepods are d i s p e r s e d towards Haro S t r a i t and to Saanich I n l e t . In an attempt to demonstrate that the p a t t e r n of i n c r e a s e in the p o p u l a t i o n at Saa9 (from May-July) c o u l d be r e l a t e d to the changes i n the S t r a i t of Georgia p o p u l a t i o n , an a n a l y s i s of v a r i a n c e was used to t e s t the d i f f e r e n c e i n the number of copepods at G1545 and Saa9 d u r i n g these three months ( t a b l e 25). A s i g n i f i c a n t d i f f e r e n c e i n the p o p u l a t i o n numbers (p=0.02) was d e t e c t e d among the months. At G1545 the p o p u l a t i o n had s t e a d i l y i n c r e a s e d from May to J u l y whereas the t o t a l numbers at Saa9 had remained the same i n May and June and then i n c r e a s e d i n J u l y ( f i g u r e 40 & 41). For both s t a t i o n s , the copepod numbers in May and June, and June and J u l y , were grouped i n t o two homogeneous 58 subsets ( t a b l e 25). T h i s i n d i c a t e d that there was a s i g n i f i c a n t r i s e i n the p o p u l a t i o n at G1545, but i t d i d not n e c e s s a r i l y l i n k t h i s to the i n c r e a s e i n the p o p u l a t i o n at Saa9. The i n c r e a s e i n numbers at G1545 i n J u l y can be a t t r i b u t e d to the l a t e r a l movement of water and/or copepods p l u s the downward m i g r a t i o n of CVs i n t o the deep c e n t r a l r e gion of the S t r a i t (Fulton,1973; Black, 1984). On the other hand, the i n c r e a s e i n numbers at Saa9 i n J u l y i s not due to the copepods becoming con c e n t r a t e d i n a deep r e g i o n of the i n l e t because the low oxygen below 150 m i s thought to act as a b a r r i e r to m i g r a t i o n , p r e v e n t i n g them from f i n d i n g refuge i n deep regions of the i n l e t ( f i g u r e 47). The i n c r e a s e i n numbers at Saa9 i n J u l y may correspond to the i n f l u x of copepods s h o r t l y a f t e r the June 5th c o l l e c t i o n p e r i o d as opposed to the t r a n s p o r t of copepods around the J u l y 14th sampling-date when most of the CVs were w e l l below the s i l l depth. However, one has to be c a u t i o u s about d e s i g n a t i n g t h i s as a r e a l i n c r e a s e i n the p o p u l a t i o n s i n c e r e p l i c a t e v e r t i c a l hauls were not made at Saa9. The d i s t r i b u t i o n of N. plumchrus was r e l a t e d to the presence of low oxygen bottom water. As mentioned p r e v i o u s l y , maximum c o n c e n t r a t i o n s of N. plumchrus were found at 150 m i n J u l y 1985 and at 160 m i n August ( t a b l e 16). An e x t r a p o l a t i o n of the low oxygen data between Saa0.8 and Saa9 f o r J u l y i n d i c a t e s that the CVs would have been s i t u a t e d c l o s e to oxygen l e v e l s of 0.20-0.30 mL L" 1 ( t a b l e 6 & 9). During August 1985, the copepods were above oxygen c o n c e n t r a t i o n s of 0.11 mL L " 1 . In J u l y 1986, r e p l i c a t e samples demonstrated that N. plumchrus occupied water c o n t a i n i n g 0.20 mL 0 2 L" 1 at 140 m and maximum c o n c e n t r a t i o n s 59 were found at 145 m (the oxygen data was c o l l e c t e d 1.5 days p r i o r to the h o r i z o n t a l haul samples; f i g u r e 47). At Saa3, the CVs were found at depths of 160, 170, and 180 m i n August, but the oxygen l e v e l at these depths were a l l g r e a t e r than 0.30 mL L" 1 ( f i g u r e 18). Hoos' (1970) data i n d i c a t e that the depth to which N. plumchrus migrates may be governed by the low oxygen regime i n Saanich I n l e t . The CVs were shown to occupy d i s c r e t e zones above oxygen c o n c e n t r a t i o n s of 0.10 and 0.36 mL L~ 1 ; however, he d i d not sample the zone, below 150 m ( t a b l e 31). Since the o b l i q u e hauls covered a depth range of 25 m, the l o c a t i o n of the CVs with respect to the oxygen content can only be estimated. The deep water renewal i n 1986 d i s p l a c e d oxygen poor water (0-0.16 mL L" 1) between 120 and 160 m at Saa0.8 ( t a b l e 10). Perhaps c o i n c i d e n t a l l y , N. plumchrus was not found i n the v e r t i c a l haul samples from t h i s r e gion although a few CVs were found above (0.5 n r 3 ) and below (0.3 n r 3 ) t h i s zone ( f i g u r e 44). Devol (1981) examined the d i s t r i b u t i o n of zooplankton with r e s p e c t to the l o c a t i o n of the d i s p l a c e d low oxygen zone i n Saanich I n l e t by measuring the r e s p i r a t o r y enzyme a c t i v i t y (ETS a c t i v i t y ) of the occupant zooplankton at a s t a t i o n which was l o c a t e d c l o s e to Saa0.8. H i s r e s u l t s showed that there was a lack of enzyme t r a n s p o r t system a c t i v i t y w i t h i n the oxygen poor region i n Saanich I n l e t ( < 5 Mg-atoms L" 1 which i s approximately e q u i v a l e n t to 0.06 mL L " 1 ) , due to a s c a r c i t y of zooplankton i n t h i s zone. U n f o r t u n a t e l y , Devol (1981) d i d not p r o v i d e an account of the s p e c i e s or q u a n t i t y of zooplankton present but he acknowledged that N. plumchrus was one of the 60 common s p e c i e s . At s t a t i o n s Saa3 and Saa9 the p o p u l a t i o n of N. plumchrus d e c l i n e d to < 0.2 irr 3 f o l l o w i n g the onset of the deep water renewal i n 1986. The displacement of the oxygen minimum l a y e r (0.77 mL L " 1 ) to 75 m i n September (Saa9) suggests that the CVs may a l s o have been t r a n s p o r t e d to shallow depths and c a r r i e d out of the i n l e t ( t a b l e 7). The low number of CVs i n the September samples i n d i c a t e d a n e g l i g i b l e o v e r w i n t e r i n g p o p u l a t i o n i n 1986. The presence of an o v e r w i n t e r i n g p o p u l a t i o n i n the c e n t r a l r e g i o n s of Saanich I n l e t has been i n d i c a t e d d u r i n g some ye a r s . Hoos (1970) found c o n c e n t r a t i o n s of 27 n r 3 at 150 m i n October 1969 and Cowen ( 1982) c o l l e c t e d c o n c e n t r a t i o n s of 5.3 i rr 3 between 0 and 200 m i n December 1974 ( t a b l e 31). The hydrographic data c o l l e c t e d i n September 1969 i n d i c a t e s that dense, oxygenated water mixed with the bottom waters of Saanich I n l e t (Hoos, 1970). An examination of the UBC data r e p o r t (#30) fo r 1969 showed that there was a displacement of low oxygen water between 120 and 175 m (0.0-0.17 mL L" 1 ) to the south of Hoos's s t a t i o n ( t a b l e 32; f i g u r e 55). However, the oxygen minimum disappeared at the s t a t i o n s l o c a t e d more c e n t r a l l y and towards the mouth ( t a b l e 32). The occurrence of higher c o n c e n t r a t i o n s of oxygen between 80-200 m i n 1969 than i n 1985 suggests that a g r e a t e r volume of water mixed with the low oxygen bottom waters ( f i g u r e 55). Anderson and Devol (1973) c o i n c i d e n t l y estimated the volume of i n t r u d i n g water below 150 m between J u l y and September 1969, using d i f f e r e n c e s i n n i t r a t e c o n c e n t r a t i o n s before and a f t e r the renewal. They estimated the volume of i n t r u d i n g water to be 4.3 61 x 10 8 m3. C a l c u l a t i o n s f o r 1985 i n d i c a t e d that 2.9 x 10 B m3 i n t r u d e d and mixed with the r e s i d e n t water below 150 m (appendix A). The c a l c u l a t i o n s were based on the oxygen c o n c e n t r a t i o n s before and a f t e r the onset of the renewal on August 7th and September 17 (appendix A). Since a d i s c r e t e zone of low oxygen water was not maintained i n 1969 the copepods aggregated above the oxygen minumum p r i o r to the renewal would have been d i s r u p t e d and mixed i n with the oxygen-containing water. On the other hand, i n 1985 a d i s c r e t e oxygen minimum was d i s p l a c e d at Saa0.8 and Saa9. T h i s i n d i c a t e d that the copepods would have been d i s p l a c e d to shallow depths s i n c e thay tended to occupy depths above the oxygen poor re g i o n and a l s o because t h i s r e g i o n would not have been d i s t u r b e d by the mixing of water d u r i n g the renewal except where the copepods were s i t u a t e d c l o s e to the slope of the b a s i n . I f we assume that the m a j o r i t y of copepods are l o c a t e d between s t a t i o n Saa9 and s l i g h t l y south of Saa3 (approximately 3.2 km) the volume of water which would need to be l o s t to account f o r the d e c l i n e i n the p o p u l a t i o n would be 3.0 x 10 8 m3. T h i s value was c a l c u l a t e d f o r a 10 m c o n c e n t r a t e d l a y e r of copepods s i t u a t e d at the 100 m contour. T h i s i s e q u i v a l e n t to the volume of water which came i n t o the i n l e t , however, i t i s not l i k e l y t h a t a l l of the o u t f l o w i n g water would have l e f t i n a 10 m l e n s . I t i s more probable that the water would have flowed out through the e n t i r e r e gion above the s i l l d u r i n g ebb t i d e (Paul LeBlond, p e r s . comm.). Th e r e f o r e , based on these rough c a l c u l a t i o n s , the p r o p o r t i o n of the N. plumchrus p o p u l a t i o n t r a n s p o r t e d out of Saanich I n l e t can not be determined. 62 The oxygen data from the UBC data report (#37) i s rather sketchy but i n d i c a t e s t h a t the deep water renewal i n 1974 d i d not d i s p l a c e a region of low oxygen to shallow depths due to a g r e a t e r volume of mixing as i n 1969 ( t a b l e 33). T h i s suggests that some of the CVs l o c a t e d i n the c e n t r a l r e g i o n of Saanich I n l e t c o u l d have been mixed to deeper depths duri n g the renewal and t h e r e f o r e account f o r the retainment of some of the CVs i n 1974. S e c h e l t I n l e t data demonstrate that N. plumchrus can s u c c e s s f u l l y overwinter at depths shallower than the deep c e n t r a l r egion of the S t r a i t of Georgia. The p h y s i c a l c h a r a c t e r i s t i c s of S e c h e l t I n l e t c o n t r a s t with the f e a t u r e s of Saanich I n l e t i n that i t i s oxygenated throughout the water column due to strong e s t u a r i n e c i r c u l a t i o n , although, i t has a very shallow s i l l (15 m) r e s t r i c t i n g the exchange of water. I t h i n k these two major d i f f e r e n c e s favour the o v e r w i n t e r i n g of N. plumchrus i n S e c h e l t I n l e t . N. plumchrus was found i n f a i r l y h igh c o n c e n t r a t i o n s (16.9 i r r 3 ) i n November 1985 at s t a t i o n Sc 1 ( f i g u r e 48). Towards the l a t t e r p a r t of February the d e n s i t y of o v e r w i n t e r i n g copepods had d e c l i n e d to 2.0 n r 3 at Sc1 but the a d u l t females contained eggs, c o n f i r m i n g that the p o p u l a t i o n was reproducing i n the i n l e t . S e c h e l t I n l e t was sampled again i n August 1986 d u r i n g which time the CVs were found at o v e r w i n t e r i n g depths below 175 m at Sc1a, and below 205 m at Sc2 and Sc2a, a deeper m i g r a t i o n than i n Saanich I n l e t ( f i g u r e 49). P r o v i d i n g the water column i s s u f f i c i e n t l y oxygenated and the bottom waters are r e l a t i v e l y u n d i s t u r b e d by water movements, N. plumchrus w i l l overwinter at the deepest p o s s i b l e depths. 63 5.2. A l t e r n a t i v e Causes for the D e c l i n e of N. plumchrus i n Saanich I n l e t A number of a l t e r n a t i v e causes f o r the d e c l i n e i n N. plumchrus d u r i n g t h e i r o v e r w i n t e r i n g p e r i o d i n Saanich I n l e t were c o n s i d e r e d . 1) While i n diapause the CVs c o u l d perhaps sink i n t o r e g i o ns of lower oxygen or, as the oxygen d e c l i n e d due to the r e s p i r a t i o n of b a c t e r i a or zooplankton, the c o n d i t i o n s at the depth of t h e i r l o c a t i o n c o u l d cause death. 2) During the deep water renewal some of the CVs may be mixed i n t o water c o n t a i n i n g low oxygen or p o t e n t i a l l y t o x i c agents such as hydrogen s u l p h i d e . 3) The shallow depths which the CVs were f o r c e d to occupy c o u l d have l e f t the copepods more v u l n e r a b l e to p r e d a t i o n . The n o t i o n , that the copepods c o u l d p o t e n t i a l l y sink i n t o a region of lower oxygen while i n diapause arose from a misconception of the 'diapause' phase i n N. plumchrus. T h i s s p e c i e s has evolved many of the c h a r a c t e r i s t i c f e a t u r e s of i n s e c t diapause, as o u t l i n e d i n Mansingh's (1971 ) c l a s s i f i c a t i o n of dormancy, which Elgmork and N i l s s e n (1978) r e f e r to as e q u i v a l e n t to copepod diapause. N. plumchrus demonstrates a c y c l i c a l change i n t h e i r l i f e h i s t o r y i n l a t e summer as the stage f i v e copepodite moves to deep depths p r i o r to the onset of f a l l . The copepods have an accumulated supply of r e s e r v e s i n the form of l i p i d s which are thought to be s u f f i c i e n t to s u s t a i n a decreased l e v e l of metabolic a c t i v i t y (Lee et a l . , 1972; H a r r i s o n et a l . , 1983). A c c o r d i n g to Mansingh's (1971) d e f i n i t i o n of diapause, the organism should be completely independent of a food supply. 6 4 As the metabolic a c t i v i t i e s of the organism become reduced i t e n t e r s what i s c o n s i d e r e d the r e f r a c t o r y stage of diapause, in which the copepod i s i n a deep t o r p i d s t a t e (Elgmork & N i l s s e n , 1978). However, t h i s s t a t e of tor p o r v a r i e s i n d u r a t i o n and i n t e n s i t y with the s p e c i e s . L i v e specimens of N. plumchrus that were captured on a monthly b a s i s from May to November 1986 d i d not show sign s of t o r p o r . The copepods a c t i v e l y swam about the thermos when the l i d was removed and i n the presence of a p i p e t t e . The f a c t that they were able to respond to environmental s t i m u l i i n d i c a t e d t h a t they were not i n the r e f r a c t o r y phase of diapause (Mansingh, 1971; Elgmork & N i l s s e n , 1978). In a d d i t i o n , when food was a v a i l a b l e the copepods ate as was demonstrated by the p r o d u c t i o n of f a e c a l p e l l e t s ( t a b l e 28). The f e e d i n g a c t i v i t y of N. plumchrus and i t s response to environmental s t i m u l i suggest that t h i s s p e c i e s was i n a s t a t e of 'low i n t e n s i t y diapause' (Mansingh, 1971). In an environment such as Saanich I n l e t where the oxygen c o u l d decrease d u r i n g the o v e r w i n t e r i n g p e r i o d , i t would be advantageous to be ab l e to respond to such changes, e s p e c i a l l y i f the organism c o u l d not t o l e r a t e anaerobic c o n d i t i o n s . I t i s t h e r e f o r e not probable that N. plumchrus would sink i n t o regions of low oxygen t o the extent that i t would threaten t h e i r s u r v i v a l . N. plumchrus appeared to be ab l e to a v o i d unfavourable oxygen c o n c e n t r a t i o n s d u r i n g August 1985 and J u l y 1986 by a l t e r i n g t h e i r depth of m i g r a t i o n ; they remained responsive to environmental s t i m u l i d u r i n g the o v e r w i n t e r i n g p e r i o d i n 1986 ( f i g u r e 17 & 47). In l i g h t of these o b s e r v a t i o n s I suggest t h a t , as the oxygen l e v e l s d e c l i n e due to the consumption of oxygen 65 through r e s p i r a t i o n , the copepods adjust t h e i r p o s i t i o n i n the water column. However, as dense water i n t r u d e s d u r i n g a renewal and mixes with the bottom water i n the i n l e t , some of the copepods c o u l d be trapped below the d i s p l a c e d oxygen minimum l a y e r . T h i s c o u l d be d e t r i m e n t a l t o t h e i r s u r v i v a l because 1) as the hydrographic data f o r 1985 i n d i c a t e s , t h i s incoming water i s low in oxygen i n September and lower i n October ( t a b l e 6 & 9), and 2) only some members of the p o p u l a t i o n may be ab l e to t o l e r a t e oxygen l e v e l s as low as 0.2 mL L " 1 . Copepods below the oxygen minimum zone i n September 1985 would presumably seek deeper depths i n response to the i n c r e a s i n g g r a d i e n t of oxygen towards the bottom. For the copepods to s u r v i v e , they would have to t o l e r a t e oxygen l e v e l s up to 0.71 mL L" 1 at Saa0.8 and 0.62 mL L" 1 at Saa9 as w e l l as p o t e n t i a l l y t o x i c agents present i n the water. The v a r i a t i o n i n the h o r i z o n t a l d i s t r i b u t i o n of the copepods i n August 1985 and J u l y 1986 ( s i g n i f i c a n t d i f f e r e n c e i n the p o p u l a t i o n mean at four depths at p=0.05) suggests that i n d i v i d u a l copepods may r e q u i r e d i f f e r e n t l e v e l s of oxygen, although o v e r w i n t e r i n g copepods i n a we l l oxygenated f j o r d may a l s o be found to occupy a range of depths ( t a b l e 27). V a r i a t i o n i n the t o l e r a n c e of i n d i v i d u a l copepods was r e a d i l y apparent i n the r e s u l t s of the low oxygen experiments. The main f a c t o r i n f l u e n c i n g t h e i r t o l e r a n c e appeared to be r e l a t e d t o the p e r i o d of time that they were h e l d i n c a p t i v i t y . As the d u r a t i o n of c a p t i v i t y i n c r e a s e d there was a c o n s i s t e n t r i s e i n the percent k i l l e d i n the low oxygen experiments ( f i g u r e 52). Many other f a c t o r s appeared to c o n t r i b u t e to the 66 v a r i a b i l i t y i n the r e s u l t s so i t soon became apparent that these experiments c o u l d only be used as a p r e l i m i n a r y b a s i s f o r f u r t h e r experiments. The most i n t e r e s t i n g source of v a r i a b i l i t y was observed i n the Saanich I n l e t copepods t e s t e d a f t e r 16 and 87 days i n c a p t i v i t y ( f i g u r e 52). Even though these copepods were t e s t e d at low oxygen l e v e l s (0.54 and 0.56 mL L~ 1 ) the percentage that s u r v i v e d was g r e a t e r than that of S t r a i t of Georgia organisms of the same time i n c a p t i v i t y ( t a b l e 5). T h i s suggests that the CVs from Saanich I n l e t may be more a c c l i m a t e d to low oxygen than those from the S t r a i t of Georgia. A f u r t h e r p o t e n t i a l source of v a r i a b i l i t y was r e c o g n i z e d i n experiments 8, 9 and 10 which were run a f t e r the f i r s t i n d i c a t i o n s of moulting. Some of the CVs t e s t e d were l i k e l y i n the process of moulting so t h e i r oxygen demand would have been e l e v a t e d and t h e i r s u s c e p t i b i l i t y to low oxygen i n t e n s i f i e d ( f i g u r e 5). Measurements of r e s p i r a t i o n i n c r u s t a c e a n s have shown that there i s a s i g n i f i c a n t r i s e i n the r e s p i r a t i o n of these organisms d u r i n g stages immediately before and a f t e r e c d y s i s , and d u r i n g the shedding of the exoskeleton (Passano, 1960; Paranjape, 1967; Hagerman, 1976). A f t e r a copepod has been at deep o v e r w i n t e r i n g depths f o r a p e r i o d of f i v e or s i x months i t i s probable that these copepods d i f f e r from the CVs c o l l e c t e d e a r l i e r ( i . e . i n June or J u l y ) . The l a s t three experiments were conducted on June, S t r a i t of Georgia specimens which were h e l d i n c a p t i v i t y f o r a short p e r i o d of time (3 to 8 days). The l e v e l of m o r t a l i t y i n these copepods was lower than p r e v i o u s l y measured, presumably due to 67 the short time spent i n c a p t i v i t y and the e a r l y stage in t h e i r o v e r w i n t e r i n g p e r i o d ( f i g u r e 52). However, the 50% m o r t a l i t y o b t a i n e d at oxygen l e v e l s of 0.47 mL L" 1 was unexpected s i n c e CVs i n Saanich I n l e t were c o l l e c t e d i n , or very c l o s e to oxygen l e v e l s of 0.20 mL L' 1 ( f i g u r e 17 & 47). The r e s u l t s of the experiments do not r u l e out the p o s s i b i l i t y that w i t h i n a p o p u l a t i o n of N. plumchrus there i s a range in t h e i r a b i l i t y to s u r v i v e low oxygen and t h e r e f o r e a percentage of the copepods mixed i n t o oxygen poor waters, may experience m o r t a l i t y . I t i s important to note that those copepods s i t u a t e d c l o s e to the mouth of the i n l e t and c o n t a c t i n g the i n f l o w i n g water, are most l i k e l y to be t r a n s p o r t e d i n t o the i n l e t ( f i g u r e 54). A few CVs c o u l d a l s o have been t r a n s p o r t e d i n through Haro S t r a i t s i n c e low c o n c e n t r a t i o n s of N. plumchrus were present i n the top 100 m d u r i n g the o v e r w i n t e r i n g p e r i o d i n the S t r a i t of Georgia ( f i g u r e 39). Of the percentage of CVs c a r r i e d i n below the oxygen minimum zone, only a few copepods would be s u s c e p t i b l e to the low oxygen c o n d i t i o n s based on the apparent v a r i a b i l i t y among i n d i v i d u a l s . Hence, t h i s i s not l i k e l y to be a major cause of m o r t a l i t y . P o t e n t i a l l y t o x i c substances such as H 2S g r a d u a l l y b u i l d up i n the anoxic bottom waters of Saanich I n l e t (Lu et a l . , 1986). Some of the H 2S i s expected to have been d i s p l a c e d with the oxygen poor water and some mixed i n t o the i n t r u d i n g water. However, i t would only remain f o r a b r i e f p e r i o d s i n c e i t would be r e a d i l y o x i d i z e d ( S t a n i e r et a l . , 1979). I t i s not known how long N. plumchrus c o u l d withstand being exposed to H 2S, or what c o n c e n t r a t i o n s may be harmful to t h e i r s u r v i v a l . The a d d i t i o n of 68 H 2S i n t o low oxygen water (<0.15 mL L" 1) has been shown to decrease the p e r i o d of s u r v i v a l i n some s p e c i e s of crustaceans in the l a b o r a t o r y (Theede, 1973). A massive d i e o f f of N. plumchrus in Saanich I n l e t due to e i t h e r low oxygen c o n d i t i o n s or the presence of t o x i c substances were expected to be d e t e c t e d i n the sediment t r a p samples. However, specimens were only captured over two p e r i o d s , May 21 to J u l y 3, and August 7 to September 17, 1985, at Saa0.8. Only small numbers were found i n e i t h e r case, two CVs i n J u l y and one i n September. Since such low numbers were c o l l e c t e d we can not draw any c o n c l u s i o n s about t h e i r cause of death; they may have been captured while the sediment t r a p s were being hauled to the s u r f a c e ( A k i r a T a n i g u c h i , p e r s . comm.). A l s o , i n the l a b o r a t o r y i t was observed that 60-75% of the dead CVs f l o a t e d to the s u r f a c e a f t e r 4-11 days ( t a b l e 29). T h i s i n d i c a t e s that i f numerous copepods were k i l l e d sediment t r a p samples would not have c o l l e c t e d a s u b s t a n t i a l p r o p o r t i o n of the copepods but they would s t i l l have c o l l e c t e d l a r g e r numbers than were found. The f i n a l a l t e r n a t i v e cause f o r the d e c l i n e i n the p o p u l a t i o n of N. plumchrus i s p r e d a t i o n . The deep m i g r a t i o n of N. plumchrus in the S t r a i t of Georgia and the P a c i f i c Ocean i s thought to be, i n p a r t , an a d a p t a t i o n f o r a v o i d i n g p r e d a t i o n although t h i s has never been adequately demonstrated to be the case ( F u l t o n , 1973; H a r r i s o n et a l . , 1983). In Saanich I n l e t N. plumchrus was f o r c e d to occupy shallow depths of 75 to 100 m f o l l o w i n g the displacement of low oxygen waters. I suggest that the i n c i d e n c e of p r e d a t i o n on t h i s s p e c i e s may have r i s e n i n September 1985 and 1986 due to a g r e a t e r amount of l i g h t 69 a v a i l a b l e f o r the d e t e c t i o n of prey and the i n c r e a s e d o v e r l a p between the d i s t r i b u t i o n of the p r e d a t o r s and the prey. In September 1985 the two n o n - v i s u a l p o t e n t i a l p r e d a t o r s predominating i n the upper 100 m at Saa9 were the siphonophore Muggiaea a t l a n t i c a and the hydromedusa Aglantha d i g i t a l e ( t a b l e 34). Mackie (1985) suggested that N. plumchrus i s probably an important food f o r g e l a t i n o u s p r e d a t o r s i n the S t r a i t of Georgia and a d j o i n i n g i n l e t s . However, the most abundant s p e c i e s , M. a t l a n t i c a , p r i m a r i l y occupies the top 50 m and t h e r e f o r e would not o v e r l a p with N. plumchrus (although t h i s s p e c i e s i s e a s i l y confused with two deeper d w e l l i n g s p e c i e s ; Mackie, 1985). T h i s leaves A. d i g i t a l e as one of the p o t e n t i a l p r e d a t o r s s i n c e i t r e s i d e s between 50 and 130 m, however, I t h i n k that i t i s l e s s l i k e l y t h a t a n o n - v i s u a l predator e x p l o i t e d the copepod aggr e g a t i o n . In the Santa Barbara Basin, C a l i f o r n i a , Calanus p a c i f i c u s  c a l i f o r n i c u s overwinters at depths of 450 m i n the oxygen minimum zone c o n t a i n i n g 0.2 mL 0 2 L" 1 ( A l l d r e d g e et a l . , 1984). Pre d a t o r s , p r i m a r i l y the deep-sea smelt Leuroglossus s t i l b i u s , have been observed to feed on the copepod aggregation from the 'WASP' submersible ( A l l d r e d g e et a l . , 1 9 8 4 ) . The s p e c i e s of deep-sea smelt found i n l o c a l waters, L. s c h m i d t i , i s the t h i r d most abundant b a t h y l a g i d f i s h found i n the S t r a i t of Georgia (Mason & P h i l l i p s , 1985). J u v e n i l e s occur with the a d u l t s below 150 m i n autumn and t h e r e f o r e may be a predator of N. plumchrus i n the S t r a i t of Georgia and Saanich I n l e t . F i s h e s such as hake, and, pink and chum salmon are l e s s l i k e l y to be f e e d i n g on N. plumchrus i n the autumn. These f i s h e s 70 feed on N. plumchrus i n s p r i n g and summer while they are j u v e n i l e s , but they s h i f t to l a r g e r s i z e d prey such as euphau s i i d s , l a t e r i n summer (LeBrasseur et a l . , 1967; Hart, 1973). The P a c i f i c h e r r i n g , Clupea p a l l a s i , c o n t i n u e s to prey upon copepods i n f a l l although euphausiids tend to be p r e f e r r e d (Hart, 1973). In Saanich I n l e t the copepods may be r e l a t i v e l y p r o t e c t e d from p r e d a t o r s i f they are capable of occupying depths that are too low i n oxygen f o r t h e i r p r e d a t o r s . However, some f i s h and hydromedusae s p e c i e s can t o l e r a t e low oxygen c o n c e n t r a t i o n s (Raymont, 1983; A l l d r e d g e , 1984). 71 6. CONCLUSIONS The f o l l o w i n g c o n c l u s i o n s and recommendations are compiled from the r e s u l t s c o l l e c t e d i n the f i e l d , the l a b o r a t o r y and the sediment t r a p s : 1. Saanich I n l e t had a n e g l i g i b l e o v e r w i n t e r i n g p o p u l a t i o n of N. plumchrus i n 1985 (September 1985 to March 1986) and i t appeared t h a t there was going to be a low o v e r w i n t e r i n g p o p u l a t i o n i n 1986 based on the September samples. 2. N. plumchrus was present i n f a i r l y high c o n c e n t r a t i o n s i n Saanich I n l e t d u r i n g the summer i n 1985; they were r e i n t r o d u c e d i n t o the i n l e t i n the s p r i n g and summer of 1986, probably from the S t r a i t of Ge o r g i a . 3. The ontogenetic m i g r a t i o n of t h i s s p e c i e s i s a f f e c t e d by the low oxygen bottom waters i n Saanich I n l e t . The CVs were d i s t r i b u t e d at or above oxygen c o n c e n t r a t i o n s -of 0.1 to 0.2 mL L" 1 i n 1985 and 1986 suggesting that they were ab l e to d e t e c t and respond t o low oxygen l e v e l s . 4. Hydrographic data i n d i c a t e a pronounced deep water renewal i n 1985 and 1986. The low oxygen zone (0-0.2 mL L~ 1) was d i s p l a c e d to shallow depths (up to 75 m) at s t a t i o n s Saa0.8 and Saa9 i n 1985. In 1986, the low oxygen zone was a l s o d i s p l a c e d to 75 m but i t contained higher c o n c e n t r a t i o n s of oxygen (0.31 mL L" 1 at Saa0.8 and 0.77 mL L~ 1 at Saa9). 5. During the renewal i n September the CVs were presumed to have been l o c a t e d above the oxygen minimum and hence at depths at or above the s i l l depth. T h i s r e s u l t e d from e i t h e r the displacement of the copepods or t h e i r avoidance of the encroaching low oxygen-containing water. 72 6. The l o s s of copepods in September 1985 and 1986, c o i n c i d e d with the appearance of the dense, i n t r u d i n g bottom waters. One primary cause f o r the r e d u c t i o n i n number of CVs i s a t t r i b u t e d to t h e i r t r a n s p o r t out of the i n l e t d u r i n g the renewal. 7. Of the years i n which a s u b s t a n t i a l p o p u l a t i o n of N. plumchrus was present i n Saanich I n l e t d u r i n g winter (1969 and 1974), the deep water renewal was of a g r e a t e r volume than in 1985 and 1986. Mixing of the i n t r u d i n g waters with water occupied by N. plumchrus i s thought to have enabled the copepods to f i n d a s u i t a b l e environment below s i l l depth. 8. N. plumchrus overwinters i n S e c h e l t I n l e t below 175 m, in r e g i o n s comparable in depth to Saanich I n l e t . However, Se c h e l t d i f f e r s from Saanich I n l e t i n that i t i s oxygenated even though i t has a very shallow s i l l that r e s t r i c t s the exchange of water. Reproductive a d u l t s (2.0 i r r 3 ) were present i n February 1986, i n d i c a t i n g the p r o d u c t i o n of a new g e n e r a t i o n w i t h i n S e c h e l t I n l e t . 9. A l t e r n a t i v e causes f o r the d e c l i n e i n p o p u l a t i o n numbers of N. plumchrus were examined. Since t h i s s p e c i e s overwinters i n a s t a t e of 'low i n t e n s i t y diapause' and appears able to d e t e c t and a v o i d low oxygen waters, changes i n oxygen c o n c e n t r a t i o n at o v e r w i n t e r i n g depths i s not l i k e l y to be a t h r e a t to t h e i r s u r v i v a l . 10. The presence of t o x i c substances such as H 2S i n deep water, may be a p o t e n t i a l hazard. However, in years when p o p u l a t i o n s of N. plumchrus were found d u r i n g the winter (1969 & 1974), the dense i n t r u d i n g water which mixed with the anoxic 73 bottom waters, d i d not r e s u l t i n the l o s s of the e n t i r e p o p u l a t i o n . In a d d i t i o n , there was no i n d i c a t i o n of a massive d i e - o f f of CVs i n the sediment t r a p s . 11. A p o r t i o n of the N. plumchrus p o p u l a t i o n i n contact with the incoming dense water may be t r a n s p o r t e d i n t o the i n l e t and 'locked' i n t o low oxygen water below the oxygen minimum zone. Due to i n d i v i d u a l v a r i a t i o n i n oxygen t o l e r a n c e , some of the CVs c a r r i e d i n t o t h i s region i n 1985 may not have been able to t o l e r a t e oxygen l e v e l s between 0.20 and 0.70 mL L " 1 . T h i s would not have been a major f a c t o r c o n t r i b u t i n g to the d e c l i n e of the p o p u l a t i o n i n September. 12. Low oxygen t o l e r a n c e experiments d i d not provide a r e l i a b l e estimate of the minimum oxygen l e v e l s which may s a f e l y be i n h a b i t e d by N. plumchrus . The main source of v a r i a b i l i t y i n the experiments appeared to be the p e r i o d of time spent i n c a p t i v i t y p r i o r to t e s t i n g . Other p o s s i b l e causes of v a r i a t i o n were the r e g i o n from which the copepods were c o l l e c t e d (Saanich I n l e t versus the S t r a i t of G e o r g i a ) , the l e n g t h of time spent o v e r w i n t e r i n g p r i o r to t e s t i n g (one month versus f i v e months), and the occurence of moulting d u r i n g some of the experiments. 13. The copepods were f o r c e d to occupy shallower depths i n Saanich I n l e t than e i t h e r the S t r a i t of Georgia or S e c h e l t I n l e t . T h i s may have i n c r e a s e d the d i s t r i b u t i o n a l o v e r l a p between N. plumchrus and t h e i r p r e d a t o r s . V i s u a l p r e d a t o r s such as the deep-sea smelt or P a c i f i c h e r r i n g may have e x p l o i t e d aggregations of N. plumchrus d u r i n g t h e i r displacement to shallow depths i n the f a l l of 1985 and 1986. 74 Recommendations: I t i s recommended that t h i s study be f o l l o w e d up with f u r t h e r work i n the f i e l d and l a b o r a t o r y . More e x t e n s i v e sampling i s r e q u i r e d p r i o r , d u r i n g and a f t e r the deep water renewal i n years of both weak and e x t e n s i v e deep water i n t r u s i o n s i n Saanich I n l e t . In the l a b o r a t o r y , the oxygen t o l e r a n c e of t h i s s p e c i e s needs to be compared between S t r a i t of Georgia copepods c o l l e c t e d from regions of r e l a t i v e l y high oxygen l e v e l s , to Saanich I n l e t copepods c o l l e c t e d from regions of low oxygen. Sediment t r a p s examined on a more r e g u l a r b a s i s c o u l d p r o v i d e more r e l i a b l e i n f o r m a t i o n about the m o r t a l i t y of N. plumchrus w i t h i n the i n l e t . The impact of p r e d a t o r s on the p o p u l a t i o n of N. plumchrus i n Saanich I n l e t d u r i n g the renewal i s s t i l l unanswered. Table 1: Station Coordinates and Maximum Depths. Station Region Latitude Longitude Maximum Depth (m) G1545 St.ofGeorgia 49deg 15.0' 123deg 45.0' 406 G1748 St.ofGeorgia 49deg 17.0' 123deg 48.0' 417 Sate Satellite Ch . 48deg 42.1' 123deg 29.1' 74 Saa9 Saanich In. 48deg 40.2' 123deg 30.2' 165 Saa3 Saanich In. 48deg 36.7' 123deg 30.0' 219 Saa0.8 Saanich In. 48deg 33.1' 123deg 32.5' 218 Sc la Sechelt In. 49deg 33.5' 123deg 47.25* 220 Sc i Sechelt In. 49deg 35.45' 123deg 48.00' 249 Sc2a Sechelt In. 49deg 38.9' 123deg 50.6' 274 Sc2 Sechelt In. 49deg 42.0' 123deg 52.0' 293 Table 2: Hydrographic and biological stations sampled in 1985. Type of Samples Station Date Hydrographic Vertical Horisontal Hauls Hauls G1545 May22 V 7 - -Sate May21 - V -Saa9 May21 V - -Saa3 May21 - V v7 Saa0.8 May21 — — G1748 July4 v7 -Sate July3 - V -Saa9 July3 V - -Saa3 July3 -Saa0.8 July3 v7 — — G1748 Aug.8 V -Sate Ang.8 - V -Saa9 Ang.7 v7 - -Saa3 Aug.7 - V v7 Saa0.8 Aug.7 — — G1748 Sept. 18 V V -Sate Sept. 18 - v7 -Saa9 Sept. 17 V V -Saa3 Sept. 17 - V -Saa0.8 Sept. 17 v7 — G1545 Oct.9 V V -Sate Oct.8 - V -Saa9 Oct.8 v7 V -Saa3 Oct.8 - V -Saa0.8 Oct.8 V — G1748 Nov.6 V v7 — Sate Nov.7 - -Saa9 Nov.7 V V -Saa3 Nov.4 - -Saa0.8 Nov.4 V v7 -Sci Nov.5 V v7 — G1545 Dec. 17 V v7 — Sate Dec. 18 - v7 -Saa9 Dec. 16 V v7 -Saa3 Dec. 16 - v7 -Saa0.8 Dec. 16 v7 -7 7 Table 3: Hydrographic and biological stations sampled in 1986. *Note: On this occasion this was an oblique haul. Type of Samples Station Date Hydrographic Vertical Horizontal Hauls Hauls G1545 Jan.28 - v7 -Sate Jan.29 - V -Saa9 Jan.29 - v 7 -Saa3 Jan.29 - V -Saa0.8 Jan.27 - V -G1545 Feb. 17 V v 7 _ Sate Feb. 17 V -Saa9 Feb. 17 - -Saa3 Feb. 17 - V -Saa0.8 Feb. 17 - V -Sc i Feb.20 v7 V -Saa3 Mar.5 - - v7* G1545 Mar. 11 V V _ Sate Mar. 10 V -Saa9 Mar. 10 V -Saa3 Mar. 10 V v7 Saa0.8 Mar. 10 V V G1545 Apr. 15 V V — Sate Apr.14 - v7 -Saa9 Apr. 14 v7 v7 -Saa3 Apr.14 - v 7 -Saa0.8 Apr.14 v 7 v 7 v 7 G1545 Mayl3 v7 v 7 — Sate May 12 - v 7 -Saa9 May 12 v7 v 7 -Saa3 May 12 - v7 -Saa0.8 Mayl2 V v7 v7 G1545 Jane3 V v7 — Sate June4 v7 -Saa9 June5 v 7 v7 -Saa3 June5 - v7 -Saa0.8 June5 V V v 7 Table 3: Hydrographic and biological stations sampled in 1986, continued. Station Date Typ« : of Samples Hydrographic Vertical Hauls Horizontal Hauls G1545 Julyl5 V v7 -Sate Julyl4 - v7 -Saa9 Julyl4 v7 -Saa9 Julyl6 - - v7 Saa3 July 14 - v7 -Saa0.8 Julyl4 V v7 -G1545 Aug.6 V v7 -Sate Aug.5 - v7 -Saa9 Aug.5 V v7 -Saa3 Aug.5 v7 v7 v7 Saa0.8 Aug.5 V v7 -Scla Aug.7 - v7 -Sc2a Aug.7 V v7 v7 Sc2 Aug.7 V v7 — G1545 Sept .9 V v7 — Sate Sept.8 - v7 Saa9 Sept.8 V V Saa3 Sept.8 - v7 -Saa0.8 Sept.8 v7 V 7 v7 Table 4: Flowmeter measurements with and without the m S C O R net. flowmeter # of revolutions # o f mean s.d. replicates inside net x=1361 113 6 without net x=2953 537 10 wire 1=0 , depth of tow (0-50 m) Table 5: Low oxygen tolerance experiments on CVs collected from the Strait of Georgia. *Note: Copepods collected from Saanich Inlet. Experiment Oxygen (mL L - 1 ) Mortality Date Collected (1985) Period of Captivity (days) Duration of Experiment (hours) Range of Oxygen (mL L _ 1 ) # Funnel Mean B.d. % Ratio 1 Ta 0.45 0.09 100 7/7 May 12 12 24 0.60-0.36 1 Tb 0.44 0.04 100 8/8 Mayl2 12 24 0.48-0.38 1 Ca 5.52 0.35 0 0/7 Mayl2 12 24 5.74-4.89 1 Cb 5.68 0.06 0 0/8 May 12 12 24 5.74-5.61 2 Ta _ _ _ _ _ _ — — 2 Tb 0.91 0.07 73 8/11 Mayl2 29 21 0.99-0.83 2 Ca - - - - - - - -2 Cb 6.04 0.02 0 0/9 Mayl2 29 21 6.06-6.00 3 Ta 0.61 0.35 70 7/10 June5 15 12 1.09-0.26 3 Tb 0.62 0.38 83 5/6 Mayl2 39 12 1.16-0.26 3 Ca 6.37 0.03 0 0/9 June5 15 12 6.33-6.42 3 Cb 6.39 0.03 0 0/6 Mayl2 39 12 6.35-6.43 4 Ta 0.83 0.31 80 8/10 June5 21 24 1.23-0.51 4 Tb 0.60 0.28 90 9/10 Mayl2 45 24 0.97-0.32 4 Ca 6.54 0.05 11 1/9 June5 21 24 6.62-6.50 4 Cb 6.53 0.06 9 1/11 May 12 45 24 6.48-6.58 5 Ta 0.56 0.26 12 1/8 Julyl4* 16 18 0.96-0.30 5 Tb - - - - - - - -5 Ca 6.81 0.22 0 0/9 Julyl4* 16 18 7.14-6.47 5 Cb - - - — — — — — 6 Ta 0.54 0.21 57 4/7 Julyl4* 87 12 0.84-0.33 6 Tb 0.46 0.12 70 7/10 Sept.9 31 12 0.64-0.38 6 Ca 6.90 0.03 0 0/7 Sept.9 31 12 6.94-6.85 6 Cb 6.89 0.03 20 2/10 Sept.9 31 12 6.94-6.86 7 Ta 0.69 0.08 70 7/10 Sept.9 52 12 0.63-0.75 7 Tb 0.87 0.03 100 9/9 Sept.9 52 12 0.90-0.85 7 Ca 6.69 0.37 10 1/10 Sept.9 52 12 6.95-6.42 7 Cb 6.60 0.35 0 0/10 Sept.9 52 12 6.85-6.35 80 Table 5: Low oxygen tolerance experiments on CVs collected from the Strait of Georgia, continued. Experiment Oxygen (mL L 1) Mortality Date Period of Duration of Range of # Funnel Mean s.d. % Ratio Collected Captivity Experiment Oxygen (1985) (days) (hours) (mL L" 1) 8 Ta 1.06 0.02 33 2/8 Nov.12 15 12 1.07-1.04 8 Tb 0.83 0.06 78 7/9 Nov.12 15 12 0.79-0.87 8 Ca 6.42 0.20 0 0/10 Nov.12 15 12 6.56-6.28 8 Cb 6.43 0.18 0 0/9 Nov.12 15 12 6.56-6.30 9 Ta 0.92 0.04 100 10/10 Oct.14 57 12 0.94-0.89 9 Tb 0.71 0.04 100 10/10 Nov.12 28 12 0.73-0.68 9 Ca 6.90 0.06 30 3/10 Oct.14 57 12 6.94-6.85 9 Cb 6.84 0.05 0 0/10 Nov.12 28 12 6.87-6.80 10 Ta 2.08 0.08 43 S/7 Nov.12 38 12 2.02-2.14 10 Tb 2.02 0.08 71 6/8 Sept.9 103 12 1.96-2.08 10 Ca 6.82 0.02 0 0/8 Nov.12 38 12 6.83-6.80 10 Cb 6.81 0.01 0 0/7 Sept.9 103 12 6.81-6.80 (1986) 11 Ta 0.95 0.12 20 2/10 June16 3 12 0.86-1.03 11 Tb 0.94 0.12 0 0/10 June16 3 12 0.85-1.02 11 Tc 2.11 0.28 0 0/10 Junel6 3 12 1.91-2.31 11 Td 2.24 0.24 0 0/9 Junel6 3 12 2.07-2.41 12 Ta 1.88 0.01 0 0/8 Junel6 6 12 1.87-1.89 12 Tb 2.18 0.03 0 0/9 Junel6 6 12 2.16-2.20 12 Ca 4.20 0.04 0 0/11 June16 6 12 4.17-4.22 12 Cb 4.24 0.16 0 0/9 Junel6 6 12 4.13-4.35 13 Ta 0.59 0.06 20 2/10 Junel6 8 12 0.55-0.63 13 Tb 0.47 0.10 50 5/10 Junel6 8 12 0.40-0.54 13 Ca 5.42 0.06 0 0/9 June16 8 12 5.37-5.46 13 Cb 5.50 0.31 0 0/10 Junel6 8 12 5.28-5.72 Table 6: Dissolved oxygen concentrations (mL L 1) at Saa9 in 1985. Depth H Jan Feb Mar Apr May Jul Aug Sep Oct Nov 0 10 4.61 5.37 5.91 6.51 9.05 5.15 3.99 4.70 4.83 3.81 20 4.98 5.29 5.54 5.75 6.17 4.76 3.74 3.59 4.77 3.69 30 5.13 4.95 5.51 5.45 5.78 5.10 3.70 3.83 2.93 3.53 50 5.08 5.02 5.10 5.18 5.56 4.44 3.63 3.42 2.47 3.37 75 4.46 4.51 4.61 4.25 4.63 3.16 2.38 0.20 0.41 3.10 100 0.25 3.12 4.66 3.76 3.38 2.33 1.17 0.49 0.17 0.31 120 0.05 0.06 3.55 2.78 3.11 1.63 0.84 0.46 0.24 0.64 140 0.06 0.09 1.91 1.06 0.72 0.90 0.31 0.62 0.51 0.63 Table 7: Dissolved oxygen concentrations (mL L _ 1 ) at Saa9 in 1986. Depth H Mar Apr May Jon Jul Aug Sep Oct Nov Dec 0 10 5.42 6.19 7.03 7.18 4.91 8.96 4.63 4.59 4.40 4.66 20 5.19 5.76 5.85 6.74 4.43 7.37 3.48 3.17 4.05 4.31 30 5.29 5.67 5.74 6.46 4.40 4.33 3.44 3.22 3.59 4.48 50 4.96 5.48 5.54 5.16 4.14 3.58 3.50 3.47 3.37 4.09 75 5.24 1.94 4.69 4.29 3.03 2.51 0.77 2.96 2.61 3.24 100 2.31 1.93 3.11 2.63 2.59 2.08 1.81 1.10 1.08 2.20 120 1.92 1.22 1.37 1.10 1.70 2.22 1.09 0.89 0.96 0.75 140 1.18 0.35 0.67 0.69 0.20 0.75 0.98 1.24 1.18 0.88 Table 8: Hydrographic data collected August 5, 1986, at station Saa3. Depth Temperature Salinity Density Oxygen H (C) (ppt) (sigma-t) (mL L- 1 ) 140 8.97 31.028 24.02 0.78 150 • 9.02 31.058 24.03 0.76 160 9.04 31.076 24.04 0.53 170 9.15 31.090 24.04 0.31 180 9.10 31.092 24.04 0.76 190 9.11 31.105 24.05 0.56 200 9.19 31.114 24.05 0.52 Table 9: Dissolved oxygen concentrations (mL L - 1 ) at Saa0.8 in 1985. Depth (m) Jan Feb Mar Apr May Jul Aug Sep Oct Nov 0 10 3.69 5.13 6.09 6.77 10.08 6.98 4.70 3.08 6.56 3.75 20 4.09 4.68 5.22 5.49 7.04 6.19 3.95 2.89 5.38 3.60 SO 3.74 4.15 4.77 5.34 6.66 5.47 3.56 2.57 2.67 3.38 50 3.79 3.21 3.84 4.53 4.94 4.24 2.77 1.92 2.04 2.33 75 3.79 3.28 3.23 2.88 2.79 2.49 1.13 0.19 0.51 1.59 100 0.87 2.54 3.69 2.01 1.32 0.74 0.29 0.25 0.16 0.68 120 0.12 0.11 3.94 1.51 0.89 0.59 0.06 0.02 0.00 0.14 140 0.02 0.00 0.59 0.20 0.06 0.20 0.03 0.08 0.07 0.14 160 0.04 0.00 0.00 0.00 0.00 0.00 0.00 0.26 0.17 0.28 180 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.41 0.39 0.35 190 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.71 0.38 0.43 Table 10: Dissolved oxygen concentrations (mL L - 1 ) at Saa0.8 in 1986. Depth H Mar Apr May Jun Jul Aug Sep Oct Nov Dec 0 . - . . • - - - - -10 5.36 6.37 6.05 7.26 5.53 6.96 4.10 4.34 4.48 3.73 20 5.25 6.28 5.87 7.22 5.44 5.55 3.33 2.95 3.23 3.73 30 4.95 5.57 5.80 6.77 4.45 4.48 3.33 2.64 3.07 3.94 50 4.75 5.11 4.63 5.29 3.29 3.68 2.82 2.24 2.56 3.43 75 4.08 4.20 3.44 3.35 1.83 1.28 0.31 0.65 1.44 2.17 100 2.48 1.71 1.34 0.86 1.23 0.48 0.30 0.26 0.20 1.48 120 1.36 0.48 0.32 0.37 0.65 0.38 0.16 0.18 0.17 0.64 140 0.67 0.35 0.20 0.18 0.19 0.13 0.00 0.18 0.18 0.19 160 0.27 0.15 0.08 0.14 0.10 0.04 0.12 0.33 0.36 0.16 180 0.24 0.11 0.14 0.09 0.07 0.00 1.09 0.68 0.38 0.22 190 0.50 0.11 0.08 0.06 0.00 0.00 1.21 0.65 0.42 0.18 Table 11: Dissolved oxygen concentrations (mL L 1) at G1545 and G1748 in 1985. Depth (m) Feb Mar Apr May Jul Aug Sep Oct Nov 0 5 -6.91 6.87 7.80 7.48 6.71 6.48 6.41 6.45 10 6.41 6.84 6.55 7.35 6.00 6.47 4.91 6.23 6.24 20 5.99 6.57 6.31 5.64 4.93 4.73 3.66 3.72 5.91 30 5.74 6.14 5.75 5.09 4.46 4.05 3.62 3.45 5.55 50 4.90 5.60 4.84 4.59 4.25 3.90 3.56 3.31 3.46 75 4.89 4.93 4.68 4.72 4.31 3.87 3.55 3.23 3.21 100 4.95 4.92 4.66 4.79 4.56 3.93 3.59 3.49 3.34 150 5.38 4.77 5.02 4.98 4.66 4.09 3.82 3.51 3.78 200 5.07 4.43 4.89 4.98 4.63 4.29 4.02 3.50 3.65 250 4.12 4.65 4.98 4.83 4.63 4.36 3.82 3.51 3.42 300 3.12 4.75 4.98 4.89 4.54 4.11 3.54 3.44 3.35 400 2.77 - - - - - - - -Table 12: Dissolved oxygen concentrations (mL L 1) at G1545 in 1986. Depth H Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 0 5 6.87 6.39 7.34 6.81 8.35 7.54 6.85 6.96 7.63 5.68 6.31 10 6.94 6.18 6.39 6.36 7.55 6.16 7.68 6.52 6.75 5.62 6.15 20 6.47 5.45 5.89 5.53 6.42 4.97 4.73 4.23 4.54 5.52 5.92 30 5.95 5.32 5.52 5.44 5.14 4.90 4.51 4.09 4.08 5.17 5.58 50 5.57 5.27 5.28 5.02 4.76 4.53 4.38 3.96 3.69 3.77 5.43 75 4.97 4.94 5.06 4.90 4.71 4.48 4.14 3.96 3.44 3.29 3.67 100 4.70 4.68 5.20 4.97 5.11 4.46 4.09 3.67 3.44 3.37 3.43 150 4.38 4.51 4.76 4.72 4.63 4.40 4.09 3.59 3.40 3.34 3.63 200 4.36 4.52 4.31 4.43 4.62 4.19 4.05 3.62 3.52 3.27 3.51 250 4.21 4.21 4.04 4.28 4.05 4.04 3.92 3.67 3.34 3.22 3.54 300 4.13 3.99 4.02 4.05 4.05 3.99 3.87 3.51 3.33 3.15 3.27 Table 13: Vertical plankton hank collected in 1985. Date Station Depth (m) Sample Number C V I C V C IV Total Number May21 Sate 0-15 17 0 12 8 20 11.56 May21 Sate 0-70 18 0 55 21 76 9.42 May21 Saa3 0-15 15 0 19 7 26 15.03 May21 Saa3 0-120 16 0 47 6 53 3.83 July4 G1748 0-150 31 0 1 0 1 0.06 July3 Sate 0-70 30 0 0 0 0 0 July3 Saa3 0-150 23 0 125 0 125 7.22 Ang8 G1748 0-150 46 0 3 0 3 0.17 Ang8 G1748 0-375 45 0 1566 0 1566 60.18 Aug8 Sate 0-70 44 0 0 0 0 0 Ang7 Saa3 0-50 39 0 0 0 0 0 Ang7 Saa3 0-190 38 0 24 0 24 1.49 Septl8 G1748 0-200 59 0 3 0 3 0.13 Sept18 G1748 200-380 60 0 652 0 652 31.41 Septl8 Sate 0-70 58 0 0 0 0 0 Sept17 Saa9 0-100 51 0 1 0 1 0.09 Sept17 Saa9 100-160 52 0 2 0 2 0.29 Septl7 Saa3 0-100 56 0 0 0 0 0 Sept17 Saa3 100-190 57 0 1 0 1 0.10 Sept17 Saa0.8 0-75 53 0 0 0 0 0 Sept17 Saa0.8 75-140 54 0 0 0 0 0 Septl7 Saa0.8 140-190 55 0 0 0 0 0 Oct9 G1545 0-150 69 0 1 0 1 0.06 Oct9 G1545 150-365 70 0 724 0 724 29.20 Oct8 Sate 0-70 68 0 0 0 0 0 Oct8 Saa9 0-100 62 0 0 0 0 0 Oct8 Saa9 100-140 61 0 0 0 0 0 Oct8 Saa3 0-100 65 0 0 0 0 0 Oct8 Saa3 100-140 66 0 0 0 0 0 Oct8 Saa3 140-210 67 0 1 0 1 0.12 Oct8 Saa0.8 0-100 64 0 0 0 0 0 Oct8 Saa0.8 0-200 63 0 0 0 0 0 Table 13: Vertical plankton hauls collected in 1985, continued. Date Station Depth (m) Sample Number C V I C V CIV Total Number (m- 3 ) Nov6 G1748 0-100 82 0 0 0 0 0 Novo G1748 100-394 81 0 1052 0 1052 31.03 Nov7 Sate 0-68 85 0 0 0 0 0 Nov7 Saa9 0-100 84 0 0 0 0 0 Nov7 Saa9 100-150 83 0 0 0 0 0 Nov4 Saa3 0-100 74 0 0 0 0 0 Nov4 Saa3 100-210 73 0 0 0 0 0 Nov4 Saa0.8 0-195 71 0 0 0 0 0 Nov4 Saa0.8 100-195 72 0 0 0 0 0 Nov5 Sc i 0-100 76 0 0 0 0 0 Nov5 Sc i 100-245 75 0 282 0 282 16.86 Decl7 G1545 0-100 D12 0 2 0 2 0.17 Decl7 G1545 100-385 D13 0 320 0 320 9.74 Decl8 Sate 0-65 D7 0 0 0 0 0 Decl6 Saa9 0-100 D l 0 0 0 0 0 Decl6 Saa9 100-150 D2 0 0 0 0 0 Decl6 Saa3 0-100 D3 0 0 0 0 0 Decl6 Saa3 100-210 D4 0 1 0 1 0.08 Decl6 Saa0.8 0-100 D5 0 0 0 0 0 Decl6 Saa0.8 100-190 D6 0 4 0 4 0.39 Table 14: Variation between replicate vertical haul samples. 80% Confidence Depth Coefficient Interval Sample Sampled of Variation Lower Upper Mean Number (m) Station % (# m" 3 ) (# m" 3 ) (# m~ 3 ) Fel8,20 80-245 Sc i 12.9 1.5 2.7 2.0 A3,6 0-80 Saa0.8 0 0.1 0.1 0.1 A2,5 80-160 Saa0.8 141.4 0.1 3.8 0.05 A17.21.18 0-80 G1545 83.0 37.2 232.7 120.6 Ma5,8 0-80 Saa0.8 47.1 0.1 0.8 0.3 Ma6,9 80-160 Saa0.8 70.7 0.03 0.8 0.2 Mal5,20 0-80 G1545 7.8 24.0 33.7 28.6 Mal6,17 80-200 G1545 44.5 0.4 3.0 1.3 Mal8,19 200-380 G1545 58.9 0.2 3.6 1.2 Jel3,14 80-120 Saa0.8 141.4 0.3 7.6 0.1 Jel5,16 120-208 Saa0.8 141.4 0.2 7.0 0.1 Jel,4 0-80 G1545 34.0 4.4 20.0 10.2 Je3,6 300-395 G1545 27.9 24.7 84.8 80.6 JU,2 100-170 Saa0.8 141.4 0.5 13.1 0.2 JU6.17 0-150 G1545 141.4 0.1 2.0 0.03 J112.13 150-250 G1545 93.5 0.1 29.3 5.1 J114.15 250-385 G1545 32.4 56.3 239.4 125.2 Au5,6 100-175 Saa3 0 0.5 0.5 0.5 Au7,8 175-205 Saa3 25.4 3.1 9.4 5.6 Aul6,17 300-395 G1545 16.9 52.8 110.6 77.9 Sel,2 0-120 Saa0.8 70.7 0.03 1.1 0.5 Se7,8 160-208 Saa0.8 47.1 0.1 0.7 0.3 Table 15: Vertical plankton hauls collected in 1986. Date Station Depth (m) Sample Number CVI CV c r v Total Number (m"») Jan28 G1545 O-lOO J20 0 0 0 0 0 Jan28 G1545 100-395 J21 224 0 0 224 6.58 Jan29 Sate 0-70 J22 0 0 0 0 0 Jan29 Saa9 0-100 J23 0 0 0 0 0 Jan29 Saa9 100-150 J24 0 0 0 0 0 Jan29 Saa3 0-100 J25 0 0 0 0 0 Jan29 Saa3 100-210 J26 1 1 0 2 0.16 Jan27 Saa0.8 0-100 J14 0 0 0 0 0 Jan27 Saa0.8 100-210 J15 1 1 0 2 0.16 Feb20 G1545 0-80 F12 0 0 0 0 0 Feb20 G1545 80-300 F14 124 0 0 124 4.89 Feb20 G1545 300-385 F13 81 0 0 81 8.26 Febl7 Sate 0-65 F l l 0 0 0 0 0 Febl7 Saa9 0-80 F9 0 0 0 0 0 Febl7 Saa9 80-150 F10 0 0 0 0 0 Febl7 Saa3 0-80 F8 0 0 0 0 0 Febl7 Saa3 80-205 F7 0 0 0 0 0 Febl7 Saa0.8 0-80 F2 0 0 0 0 0 Febl7 Saa0.8 80-192 F I 0 1 0 1 0.08 Feb20 Sc i 0-80 F17 0 0 0 0 0 Feb20 Sc i 0-80 F19 0 0 0 0 0 Feb20 S c i 80-245 F18 35 0 0 35 1.84 Feb20 Sc i 80-245 F20 42 0 0 42 2.21 Mar 11 G1545 0-200 Mh20 15 0 0 15 0.65 M a r l l G1545 200-395 M h l 9 136 0 0 136 6.05 MarlO Sate 0-70 Mhl4 0 0 0 0 0 MarlO Saa3 0-80 Mhl2 0 0 0 0 0 MarlO Saa3 80-215 Mhl3 1 0 0 1 0.06 MarlO SaaO.8 0-80 M h l l 0 0 0 0 0 MarlO SaaO.8 80-200 MhlO 0 0 0 0 0 Apr l5 G1545 0-80 A17 0 101 2080 2181 236.29 Apr l5 G1545 0-80 A21 0 25 420 445 48.21 Apr l5 G1545 0-250 A18 0 20 716 736 25.53 Apr l5 G1545 80-250 A19 0 4 16 20 1.02 Apr l5 G1545 80-250 A22 2 7 15 24 1.22 Apr l5 G1545 250-390 A20 2 0 2 4 0.25 Apr l4 Sate 0-72 A16 0 0 26 26 3.13 Apr l4 Saa9 0-80 A14 0 4 4 8 0.87 Apr l4 Saa9 80-155 A15 0 0 0 0 0 Apr l4 Saa3 0-160 A13 0 2 4 6 0.33 Aprl4 Saa3 160-213 A12 0 0 0 0 0 Table 15: Vertical plankton hauls collected in 1986, continued. Date Station Depth (m) Sample Number C V I C V c r v Total Number Apr l4 SaaO.8 0-80 A3 0 0 I 1 0.11 Apr l4 SaaO.8 0-80 A6 0 0 I 1 0.11 Apr l4 SaaO.8 80-160 A2 0 0 0 0 0 Apr l4 SaaO.8 80-160 A5 1 0 0 1 0.11 Apr l4 SaaO.8 160-205 A l 0 0 0 0 0 Apr l4 SaaO.8 160-205 A4 0 0 0 0 0 Mayl3 G1545 0-80 Ma l5 0 267 n 278 30.12 Mayl3 G1545 0-80 Ma20 0 243 6 249 26.98 Mayl3 G1545 80-200 Mal6 0 20 3 23 1.66 Mayl3 G1545 80-200 M a l 7 0 11 1 12 0.87 May 13 G1545 200-380 Mal8 0 14 0 14 0.67 Mayl3 G1545 200-380 M a l 9 1 33 0 34 1.64 Mayl2 Sate 0-72 Ma l4 0 3 5 8 0.96 Mayl2 Saa9 0-155 Mal3 0 17 8 25 1.40 May 12 Saa3 0-80 M a l l 0 11 5 16 1.73 May 12 Saa3 80-214 Mal2 0 1 0 1 0.07 May 12 SaaO.8 0-80 Ma5 0 0 2 2 0.22 May 12 SaaO.8 0-80 Ma8 0 0 4 4 0.43 May 12 SaaO.8 80-160 Ma6 0 0 3 3 0.33 Mayl2 SaaO.8 80-160 Ma9 0 1 0 1 0.11 May 12 SaaO.8 160-200 Ma7 0 0 0 0 0 Mayl2 SaaO.8 160-210 MalO 0 0 0 0 0 Jun3 G1545 0-80 Jel 0 71 0 71 7.69 Jun3 G1545 0-80 Je4 0 . 116 1 117 12.68 Jun3 G1545 80-200 Je2 0 27 0 27 1.95 Jun3 G1545 200-300 Je7 0 203 0 203 17.61 Jun3 G1545 200-395 Je3 0 1300 0 1300 57.80 Jun3 G1545 200-395 Je6 0 872 0 872 38.77 Jun4 Sate 0-70 Je8 0 0 0 0 0 Jun5 Saa9 0-120 Je9 0 4 0 4 0.29 Jun5 Saa9 120-157 JelO 0 20 0 20 4.69 Jun5 Saa3 0-120 Je21 0 3 0 3 0.22 Jun5 Saa3 120-215 Je22 0 14 0 14 1.28 Jun5 SaaO.8 0-80 J e l l 0 0 0 0 0 Jun5 SaaO.8 0-80 Jel2 0 0 0 0 0 Jun5 SaaO.8 80-120 Jel3 0 0 0 0 0 Jun5 SaaO.8 80-120 Jel4 0 1 0 1 0.22 Jun5 SaaO.8 120-208 Jel5 0 0 0 0 0 Jun5 SaaO.8 120-208 Jel6 0 2 0 2 0.20 Table 15: Vertical plankton hauls collected in 1986, continued. Date Station Depth (m) Sample Number C V I C V CIV Total Number Jull5 G1545 0-150 J116 0 1 0 1 0.06 Jull5 G1545 0-150 J117 0 0 0 0 0 Jull5 G1545 150-250 J112 0 98 0 98 8.50 Jull5 G1545 150-250 J113 0 20 0 20 1.73 Jull5 G1545 250-385 J114 0 2396 0 2396 153.88 Jull5 G1545 250-385 J115 0 1502 0 1502 96.47 Jull4 Sate 0-70 J i l l 0 0 0 0 0 Jull4 Saa9 0-80 J110 0 0 0 0 0 Jull4 Saa9 80-155 J19 0 61 0 61 7.05 Jull4 Saa3 0-100 J17 0 0 0 0 0 Jull4 Saa3 100-195 J18 0 12 0 12 1.10 Jull4 Saa0.8 0-100 J13 0 0 0 0 0 Jull4 Saa0.8 0-100 J14 0 0 0 0 0 Jull4 Saa0.8 100-170 J l l 0 0 0 0 0 Jull4 Saa0.8 100-170 J12 0 3 0 3 0.37 Jull4 Saa0.8 170-208 J15 0 0 0 0 0 Jull4 Saa0.8 170-208 J16 0 0 0 0 0 Aug6 G1545 0-200 A u l 9 0 1 0 1 0.04 Aug6 G1545 200-300 A u l 8 0 576 0 576 49.96 Aug6 G1545 300-395 A u l 6 0 956 0 956 87.23 Aug6 G1545 300-395 A u l 7 0 752 0 752 68.61 Aug5 Sate 0-70 A u l 5 0 0 0 0 0 Aug5 Saa9 0-100 Aul4 0 0 0 0 0 Aug5 Saa9 100-153 Au l3 0 3 0 3 0.49 Aug5 Saa3 0-100 Au3 0 0 0 0 0 Aug5 Saa3 0-100 Au4 0 0 0 0 0 Aug5 Saa3 100-175 Au5 0 4 0 4 0.46 Aug5 Saa3 100-175 Au6 0 4 0 4 0.46 Aug5 Saa3 175-205 Au7 0 16 0 16 4.62 Aug5 Saa3 175-205 Au8 0 23 0 23 6.65 Aug5 Saa0.8 0-100 Au2 0 0 0 0 0 Aug5 Saa0.8 100-203 A u l 0 2 0 2 0.17 Aug7 Sc la 0-175 Au20 0 0 0 0 0 Aug7 Scla 175-210 Au21 0 130 0 130 32.18 Aug7 Sc2a 0-175 Au24 0 0 0 0 0 Aug7 Sc2a 175-205 Au23 0 0 0 0 0 Aug7 Sc2a 205-265 Au22 0 1 0 1 0.14 Aug7 Sc2 0-205 Au28 0 0 0 0 0 Aug7 Sc2 205-285 Au29 0 35 0 35 3.80 Table 15: Vertical plankton hauls collected in 1986, continued. Date Station Depth Sample C V I C V CIV Total Number (m) Number ( m - 3 ) Sep9 G1545 0-120 Se20 0 0 0 0 0 Sep9 G1545 0-120 Se21 0 0 0 0 0 Sep9 G1545 120-250 Se22 0 2 0 2 0.13 Sep9 G1545 250-372 Se23 0 502 0 502 35.68 Sep8 Sate 0-72 Sel9 0 0 0 0 0 Sep8 Saa9 0-100 Sel8 0 0 0 0 0 Sep8 Saa9 100-150 Sel7 0 1 0 1 0.17 Sep8 Saa3 0-120 Sel6 0 0 0 0 0 Sep8 Saa3 120-210 Sel5 0 1 0 1 0.07 Sep8 Saa0.8 0-50 Se4 0 0 0 0 0 Sep8 Saa0.8 0-120 Sel 0 2 0 2 0.25 Sep8 Saa0.8 0-120 Se2 0 6 0 6 0.74 Sep8 Saa0.8 120-160 Se5 0 0 0 0 0 Sep8 Saa0.8 120-160 Se6 0 0 0 0 0 Sep8 Saa0.8 160-208 Se7 0 1 0 1 0.18 Sep8 Saa0.8 160-208 Se8 0 2 0 2 0.36 Table 16: Horizontal plankton hauls collected at station Saa3 in 1985. Date Depth (m) Sample Number C V I C V crv Total Number (m- 3 ) Volume Filtered (m- 3 ) May 21 5 1 0 3 2 5 3.00 1.67 May 21 5 6 0 6 4 10 7.58 1.32 May21 5 7 0 10 4 14 10.69 1.31 May21 50 2 0 1 2 3 1.01 2.97 May 21 50 8 0 1 0 1 1.71 0.58 May 21 100 3 0 0 0 0 0 3.17 May21 100 9 0 0 0 0 0 0.55 May21 120 4 0 18 0 18 5.10 3.53 May21 120 10 0 1 0 1 1.98 0.50 May 21 150 5 0 96 0 96 33.27 2.89 July3 5 26 0 0 0 0 0 2.43 July3 50 22 0 0 0 0 0 4.36 July3 100 21 0 0 0 0 0 5.93 July3 100 27 0 0 0 0 0 4.70 July3 120 20 0 0 0 0 0 4.95 July3 120 28 0 0 0 0 0 6.14 July3 150 19 0 317 0 317 75.61 4.19 July3 150 19 0 0 0 0 0 0.55 Aug7 110 37 0 0 0 0 0 4.40 Aug7 130 36 0 2 0 2 0.42 4.81 Aug7 140 50 0 3 0 3 0.74 4.07 Aug7 145 49 0 2 0 2 1.18 1.70 Aug7 150 48 0 0 0 0 0 1.63 Aug7 155 47 0 3 0 3 1.49 2.01 Aug7 160 43 0 25 0 25 6.04 4.14 Aug7 170 42 0 0 0 0 0 4.33 Aug7 180 41 0 0 0 0 0 4.40 Aug7 190 40 0 0 0 0 0 4.44 91 Table 17: Horizontal and * oblique plankton hauls collected in 1986. Date Station Depth (m) Sample Number C V I C V crv Total Number (m- 3 ) Volume Filtered (m- 3 ) Mar5* Saa3 0-25 Mh5 0 0 0 0 0 20.8 Mar5* Saa3 25-75 Mh4 0 0 0 0 0 41.6 Mar5* Saa3 75-100 Mh3 0 0 0 0 0 27.8 Mar5* Saa3 100-150 Mh2 0 0 l 1 0.02 55.5 Mar5* Saa3 150-200 M h l 0 0 0 0 0 63.3 MarlO Saa3 5 Mh9 0 0 0 0 0 8.54 MarlO Saa3 20 Mh8 0 0 0 0 0 7.50 MarlO Saa3 50 Mh7 0 0 0 0 0 8.86 MarlO Saa3 90 Mh6 0 0 0 0 0 8.22 Apr l4 Saa0.8 5 A10 0 0 3 3 0.60 5.04 Apr l4 Saa0.8 40 A9 0 0 0 0 0 2.59 Apr l4 Saa0.8 150 A8 0 0 0 0 0 1.25 Apr l4 Saa0.8 160 A7 0 0 0 0 0 4.74 Mayl2 Saa0.8 40 Ma3 0 1 3 4 0.62 6.42 Mayl2 Saa0.8 150 Ma4 0 0 0 0 0 9.03 Jun5 Saa0.8 90 Je20 0 2 0 2 0.34 5.41 Jun5 Saa0.8 100 Jel9 0 0 0 0 0 6.43 Jun5 Saa0.8 110 Jel8 0 3 0 3 0.43 7.03 Jun5 Saa0.8 120 Jel7 0 0 0 0 0 6.44 Jull6 Saa9 120 J142 0 2 0 2 0.29 6.98 Jull6 Saa9 120 J137 0 19 0 19 3.56 5.34 Julie Saa9 130 J136 0 0 0 0 0 5.76 Julie Saa9 130 J135 0 0 0 0 0 4.58 Julie Saa9 135 J134 0 0 0 0 0 0.12 Jul 16 Saa9 135 J121 0 0 0 0 0 2.72 Jull6 Saa9 135 J125 0 8 0 8 1.55 5.16 Jul l6 Saa9 135 J129 0 18 0 18 2.52 7.13 Julie Saa9 135 J133 0 14 0 14 2.87 4.88 Jull6 Saa9 140 J120 0 35 0 35 12.72 2.75 Julie Saa9 140 J124 0 10 0 10 3.92 2.55 Julie Saa9 140 J128 0 34 0 34 5.60 6.07 Julie Saa9 140 J132 0 57 0 57 11.27 5.06 Jull6 Saa9 140 J140 0 31 0 31 4.31 7.20 Table 17: Horizontal and * oblique plankton hauls collected in 1986, continued. Date Station Depth (m) Sample Number C V I C V c r v Total Number ( m - 3 ) Volume Filtered (m- 3 ) Jull6 Saa9 145 J119 0 7 0 7 4.72 1.48 Jull6 Saa9 145 J123 0 43 0 43 10.70 4.02 Jull6 Saa9 145 J127 0 76 0 76 10.80 7.04 Jull6 Saa9 145 J131 0 86 0 86 18.87 4.56 Jull6 Saa9 145 J139 0 28 0 28 4.56 6.14 Jull6 Saa9 150 J118 0 5 0 5 2.28 2.19 Jul l6 Saa9 150 J122 0 0 0 0 0 0.18 Jull6 Saa9 150 J126 0 9 0 9 1.25 7.19 Jull6 Saa9 150 J130 0 4 0 4 2.95 1.35 Aug5 Saa3 160 Au l2 0 1 0 1 0.25 3.95 Aug5 Saa3 170 A u l l 0 11 0 11 2.96 3.72 Aug5 Saa3 180 A u l 6 0 16 0 16 3.37 4.74 Aug5 Saa3 190 Au9 0 0 0 0 0 0.25 Aug7 Sc2a 170 Au27 0 1 0 1 0.32 3.10 Aug7 Sc2a 180 Au26 0 0 0 0 0 3.65 Aug7 Sc2a 230 Au25 0 0 0 0 0 4.30 Sep8 SaaO.8 110 Sel4 0 0 0 0 0 3.49 Sep8 SaaO.8 115 Sel3 0 0 0 0 0 7.81 Sep8 SaaO.8 120 Sel2 0 1 0 1 0.18 5.41 Table 18. ANOVA-Strait of Georgia counts, f a l l v e rsus s p r i n g and summer. Transformed water column t o t a l counts. F a l l (1985) Spring/Summer(1986) Aug 4.35637 Apr 4 .66318 Sept 3.65804 Apr 3 .74840 Oct 3.73308 Apr 3 .42746 Nov 4.02164 May 3 .15982 May 3 .10584 Jun 4 .25698 Jun 3 .99294 J u l 4 .77987 J u l 4 .36907 A n a l y s i s of v a r i a n c e t a b l e Source SEASON MONTH SEA*MON R e s i d T o t a l Sum of squares 0.33564E-01 2.7941 1 .3480 0.30449 4.4801 DF 1 3 3 4 1 1 Mean square 0.33564E-01 0.93137 0.44933 0.76123E-01 F - r a t i o Prob. 0.44092 12.235 5.9027 0.54300 0.01750 0.05961 Test term: RESIDUAL COUNT O v e r a l l mean 4.4483 O v e r a l l standard d e v i a t i o n 0.63819 Homogeneity of v a r i a n c e t e s t B a r t l e t t F a c t o r s Chi-square P r o b a b i l i t y SEASON 1.2057 0.27218 DF S i z e warn < 10 M u l t i p l e range tests-SEASON F - r a t i o i s not s i g n i f i c a n t a t p r o b a b i l i t y 0.54300 Homogeneity of v a r i a n c e t e s t B a r t l e t t F a c t o r s Chi-square P r o b a b i l i t y MONTH 0.67486 0.87910 DF 3 S i z e warn < 10 M u l t i p l e range tests-MONTHS S c h e f f e t e s t at 5% p r o b a b i l i t y l e v e l There a re 2 homogeneous subsets which are l i s t e d as f o l l o w s ( .2, .1; .3 ) ( . 1, .3, .4 ) Bo n f e r r o n i t e s t at 5% p r o b a b i l i t y l e v e l There a re 2 homogeneous subsets which are l i s t e d as f o l l o w s ( .2, .1, .3 ) ( .1, .3, .4 ) Minimal t e s t at 5% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are l i s t e d as f o l l o w s ( .2, . 1 , .3 ) ( . 1 , .3, .4 ) Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn SEA,MON 2.1248 0.54690 3 < 10 M u l t i p l e range tests-SEASON,MONTH F - r a t i o i s not s i g n i f i c a n t a t p r o b a b i l i t y 0.05961 Table 19. ANOVA-Strait of Georgia counts, f a l l 1985 versus f a l l 1986. Transformed water column t o t a l counts. (1985) (1986) Aug 4.35637 Aug 4.33619 Sep 3.65804 Sep 4.21410 Sep 3.47125 A n a l y s i s of v a r i a n c e t a b l e Sum of Mean Source squares DF square F - r a t i o Prob. YEAR 0. 18660E-01 1. 0.18660E-01 2.5036 0.35881 MONTH 0.67148 1 . 0.67148 90.095 0.06682 YR*MON 0.31840E-02 1 . 0.31840E-02 0.42721 0.63145 R e s i d 0.74530E-02 1 . 0.74530E-02 T o t a l 0.68212 4. O v e r a l l O v e r a l l mean standard d e v i a t i o n COUNT 4.0072 0.41295 Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn YEAR 0.27670E-02 0.95805 1 < 10 M u l t i p l e range tests-YEAR F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.35881 Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn MONTH 0.30163 0.58286 1 < 10 M u l t i p l e range tests-MONTH F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.06682 M u l t i p l e range tests-YEAR*MONTH F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.63145 Table 20. ANOVA-Saanich I n l e t counts f o r Saa3, May, J u l y , and August, 1985 and 1986. Transformed water column t o t a l counts, (1985) May 2.21236 J u l 2.62653 Aug 1.88818 May J u l Aug Aug (1986) 1 .76234 1.64375 1.82056 1.93318 A n a l y s i s of v a r i a n c e t a b l e Sum of Mean Source squares DF square F - r a t i o Prob. YEAR 0.31445 1 . 0.31445 49.586 0.08981 MONTH 0.41358E-01 2. 0.20679E-01 3.2609 0.36462 YR*MON 0.26982 2. 0.13491 21.274 0.15154 Res i d 0.63416E-02 1 . 0.63416E-02 T o t a l 0.66837 6. O v e r a l l O v e r a l l mean standard d e v i a t i o n COUNT 1.9838 0.33376 Homogeneity of v a r i a n c e t e s t F a c t o r s YEAR B a r t l e t t Chi-square 2.3842 P r o b a b i l i t y 0.12257 DF 1 S i z e warn < 10 M u l t i p l e range tests-YEAR F - r a t i o i s not s i g n i f i c a n t a t p r o b a b i l i t y 0.08981 M u l t i p l e range t e s t s S c h e f f e t e s t at 10% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are l i s t e d as f o l l o w s ( 2. ) ( 1. ) B o n f e r r o n i t e s t at 10% p r o b a b i l i t y l e v e l There a re 2 homogeneous subsets which a re l i s t e d as f o l l o w s ( 2. ) ( 1. ) Minimal t e s t at 10% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are l i s t e d as f o l l o w s ( 2. ) ( 1. ) Homogeneity of v a r i a n c e t e s t B a r t l e t t F a c t o r s Chi-square MONTH 4.9798 P r o b a b i l i t y 0.08292 DF 2 S i z e warn < 10 M u l t i p l e range tests-MONTH F - r a t i o i s not s i g n i f i c a n t a t p r o b a b i l i t y 0.36462 M u l t i p l e range t e s t s S c h e f f e t e s t a t 10% p r o b a b i l i t y l e v e l There i s 1 homogeneous subset which i s l i s t e d as f o l l o w s : ( 2 2 , 2 1 , 2 3 , 1 3 , 1 1 , 1 2 ) B o n f e r r o n i t e s t at 10% p r o b a b i l i t y l e v e l There i s 1 homogeneous subset which i s l i s t e d as f o l l o w s : ( 2 2 , 2 1 , 2 3 , 1 3 , 1 1 , 1 2 ) Minimal t e s t at 10% p r o b a b i l i t y l e v e l There i s 1 homogeneous subset which i s l i s t e d as f o l l o w s : ( 2 2 , 2 1 , 2 3 , 1 3 , 1 1 , 1 2 ) Table 21. ANOVA-Saanich I n l e t counts from A p r i l through August 1986. Transformed water column t o t a l counts. (Saa9) (Sa a3) (SaaO .8) Apr 1.51572 Apr 1 .43097 Apr 1 .00000 Apr 1 .14870 May 1.90365 May 1 .76234 May '1 .37973 May 1 .37973 Jun 1.88818 Jun 1 .76234 Jun 0 Jun 1 .24573 J u l 2.27544 J u l 1 .64375 J u l 0 J u l 1 .24573 Aug 1.24573 Aug 1 .82056 Aug 1 .14870 Aug 1 .93318 A n a l y s i s of v a r i a n c e t a b l e Sum of Mean Source squares DF square STATION MONTH STN*MON Res i d . T o t a l COUNT 3.0118 0.36343 1.2731 1.5692 6.3308 2. 4. 6. 5. 19. 1.5059 0.90858E-01 0.15913 0.31385 F - r a t i o 4.7982 0.28950 0.50704 O v e r a l l mean 1.3865 O v e r a l l standard d e v i a t i o n 0.57723 Prob. 0.06868 0.87333 0.81244 Homogeneity of v a r i a n c e t e s t F a c t o r s STATION B a r t l e t t Chi-square 5.6840 P r o b a b i l i t y 0.05831 DF 2 S i z e warn < 10 M u l t i p l e range tests-STATION F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.06868 M u l t i p l e range t e s t s S c h e f f e t e s t at 10% p r o b a b i l i t y l e v e l There i s 1 homogeneous subset which i s l i s t e d as f o l l o w s : ( 3., 2., 1. ) Bo n f e r r o n i t e s t at 10% p r o b a b i l i t y l e v e l There i s 1 homogeneous subset which i s l i s t e d as f o l l o w s : ( 3., 2., 1. ) Minimal t e s t at 10% p r o b a b i l i t y l e v e l There i s 1 homogeneous subset which i s l i s t e d as f o l l o w s : ( 3., 2., 1. ) Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn MONTH 7.9520 0.09335 4 < 10 M u l t i p l e range tests-MONTH F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.87333 Homogeneity of v a r i a n c e t e s t STATION,MONTH I n c a l c u l a b l e due to standard d e v i a t i o n of zero M u l t i p l e range tests-STATION,MONTH F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.81244 Table 22. ANOVA-Saanich I n l e t counts f o r Saa9 and Saa0.8, A p r i l through August 1986. Transformed water column t o t a l counts. (Saa9) (Saa0.8) Apr 1.51572 Apr 1.00000 Apr 1 . 14870 May 1.90365 May 1 .37973 May 1.37973 Jun 1 .88818 Jun 0 Jun 1.24573 J u l 2.27544 J u l 0 J u l 1.24573 Aug 1 .24573 Aug 1.14870 A n a l y s i s of v a r i a n c e t a b l e Sum of Mean Source squares DF square F- r a t i o Prob. STATION 2.1964 1 . 2.1964 5. 6214 0.07674 MONTH 0.48538 4. 0.12134 0. 31056 0.85815 STN*MON 1 .0092 4. 0.25229 0. 64570 0.65897 Res i d 1.5629 4. 0.39073 T o t a l 5.1973 13. O v e r a l l O v e r a l l mean standard d e v i a t i o n COUNT 1.2412 0.63229 Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn STATION 0.48875 0.48449 1 < 10 M u l t i p l e range t e s t s S c h e f f e t e s t at 10% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are ( 2. ) ( 1. ) Bo n f e r r o n i t e s t at 10% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are ( 2. ) ( 1. ) Minimal t e s t at 10% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are ( 2. ) ( 1. ) Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn MONTH 7.5529 0.10940 4 < 10 l i s t e d as f o l l o w s l i s t e d as f o l l o w s l i s t e d as f o l l o w s M u l t i p l e range t e s t s F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.85815 Homogeneity of v a r i a n c e t e s t STATION,MONTH U n c a l c u l a b l e due to standard d e v i a t i o n of zero Table 23. ANOVA-Saanich I n l e t counts f o r Saa3 and SaaO.8, A p r i l through August 1986. Transformed water column t o t a l v a l u e s . (Saa3) (SaaO.8) Apr 1.43097 Apr 1.00000 Apr 1.14870 May 1.76234 May 1.37973 May 1.37973 Jun 1.76234 Jun 0 Jun 1.24573 J u l 1.64375 J u l 0 J u l 1.24573 Aug 1.82056 Aug 1.14870 Aug 1.93318 A n a l y s i s of v a r i a n c e t a b l e Sum of Mean Source squares DF square F - r a t i o Prob. STATION 1 .7548 1 . 1 . 7548 5. 5911 0. 06439 MONTH 0 .66826 4. 0. 16707 0. 53231 0. 71949 STN*MON 0 .34152 4. 0. 85380E-01 0. 27204 0. 88436 Re s i d 1 .5692 5. 0. 31385 T o t a l 4 .7452 14. O v e r a l l O v e r a l l mean standard d e v i a t i o n COUNT 1.2601 0.58219 Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn STATION 5.6262 0.01769 1 < 10 M u l t i p l e range t e s t s S c h e f f e t e s t a t 10% p r o b a b i l i t y l e v e l There a re 2 homogeneous subsets which are l i s t e d as f o l l o w s ( 2. ) ( 1. ) Bo n f e r r o n i t e s t at 10% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are l i s t e d as f o l l o w s ( 2. ) ( 1. ) Minimal t e s t at 10% p r o b a b i l i t y l e v e l There a re 2 homogeneous subsets which are l i s t e d as f o l l o w s ( 2. ) ( 1. ) Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn MONTH 5.4340 0.24559 4 < 10 103 M u l t i p l e range t e s t s F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.71949 Homogeneity of v a r i a n c e t e s t STATION,MONTH I n c a l c u l a b l e due to standard d e v i a t i o n of z e r o . 104 Table 24. ANOVA-Saanich I n l e t counts f o r Saa9 and Saa3, A p r i l through August 1986. Transformed water column t o t a l counts, Apr May Jun J u l Aug (Saa9) 1 .51572 1 .90365 1 .88818 2.27544 1.24573 (Saa3) Apr 1.43097 May 1.76234 Jun 1.76234 J u l 1.64375 Aug 1.82056 Aug 1.93318 A n a l y s i s of v a r i a n c e t a b l e Sum of Mean Source squares DF square F - r a t i o Prob. STATION 0.18923E-02 1 . 0. 189E-02 0.29839 0.68171 MONTH 0.28402 4. 0. 710E-01 11.197 0.22006 STN*MON 0.48468 4. 0. 121 19.107 0.16973 R e s i d 0.63416E-02 1 . 0. 634E-02 T o t a l 0.77945 10. O v e r a l l O v e r a l l mean standard d e v i a t i o n COUNT 1.7438 0.27919 Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn STATION 2.6370 0.10440 1 < 10 M u l t i p l e range t e s t s F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.68171 Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn MONTH 4.1747 0.38287 4 < 10 M u l t i p l e range tests-MONTH F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.22006 M u l t i p l e range t e s t s F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.16973 Tab le 25. ANOVA-Saanich I n l e t counts at Saa9 ver sus S t r a i t of Georg i a c o u n t s , 1986. Trans formed water column t o t a l c o u n t s . (Saa9) (G1545) May 1. 90365 May 3.15982 May 3.10584 Jun 1. 88818 Jun 4.25698 Jun 3.99294 J u l 2. 27544 J u l 4.77987 J u l 4.36907 A n a l y s i s of v a r i a n c e t a b l e Sum of Mean Source squares DF square F - r a t i o Prob. STATION 7.3856 1 . 7.3856 183.58 0.00087 MONTH 1 .7918 2. 0.89590 22.269 0.01585 STN*MON 0.48083 2. 0.24041 5.9758 0.08988 Re s i d 0. 12069 3. 0.40231E- 01 T o t a l 9.7789 8. O v e r a l l O v e r a l l mean s tandard d e v i a t i o n COUNT 3.3035 1.1056 Homogeneity of v a r i a n c e test " B a r t l e t t F a c t o r s C h i - s q u a r e P r o b a b i l i t y STATION 2.0631 0.15090 M u l t i p l e range t e s t s S c h e f f e t e s t a t 5% p r o b a b i l i t y l e v e l There a re 2 homogeneous subset s which a re ( 1. ) ( 2. ) B o n f e r r o n i t e s t a t 5% p r o b a b i l i t y l e v e l There a re 2 homogeneous subset s which a re ( 1. ) ( 2. ) M in ima l t e s t a t 5% p r o b a b i l i t y l e v e l There a re 2 homogeneous subset s which a re ( 1. ) ( 2. ) Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s C h i - s q u a r e P r o b a b i l i t y DF warn MONTH 0.70493 0.70295 2 < 10 M u l t i p l e range tests-MONTH S c h e f f e t e s t a t 5% p r o b a b i l i t y l e v e l There a re 2 homogeneous subset s which a re l i s t e d as f o l l o w s ( . 1 , .2 ) ( . 2 , .3 ) S i z e DF warn 1 < 10 l i s t e d as f o l l o w s l i s t e d as f o l l o w s l i s t e d as f o l l o w s B o n f e r r o n i t e s t at 5% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are l i s t e d as f o l l o w s ( .1, .2 ) ( .2, .3 ) Minimal t e s t at 5% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are l i s t e d as f o l l o w s ( .1, .2 ) ( .2, .3 ) Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn STN,MON 1.8838 0.38989 2 < 10 M u l t i p l e range t e s t s F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.08988 Table 26. ANOVA-Saanich I n l e t counts at Saa0.8 versus S t r a i t of Georgia counts, 1986. Transformed water column t o t a l counts. (Saa0.8) (G1545) May 1.37973 May 3.15982 May 1.37973 May 3.10584 Jun 0 Jun 4.25698 Jun 1.24573 Jun 3.99294 J u l 0 J u l 4.77987 J u l 1.24573 J u l 4.36907 A n a l y s i s of v a r i a n c e t a b l e Sum of Mean Source sguares DF square F - r a t i o Prob. STATION 28.255 1 . 28.255 101.36 0.00006 MONTH 0.24211 2. 0.12105 0.4343 0.66659 STN*MON 2.6982 2. 1 .3491 4.8396 0.05604 R e s i d 1.6725 6. 0.27876 T o t a l 32.868 1 1 . O v e r a l l O v e r a l l mean standard d e v i a t i o n COUNT 2.4096 1.7286 Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn STATION 0.72875E-04 0.99319 1 < 10 M u l t i p l e range t e s t s S c h e f f e t e s t at 5% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are l i s t e d as f o l l o w s : ( 1. ) ( 2. ) Bo n f e r r o n i t e s t at 5% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are l i s t e d as f o l l o w s : ( 1. ) ( 2. ) Minimal t e s t a t 5% p r o b a b i l i t y l e v e l There are 2 homogeneous subsets which are l i s t e d as f o l l o w s : ( 1. ) ( 2. ) Homogeneity of v a r i a n c e t e s t B a r t l e t t S i z e F a c t o r s Chi-square P r o b a b i l i t y DF warn MONTH 1.7340 0.42022 2 < 10 M u l t i p l e range tests-MONTH F - r a t i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.66659 Homogeneity of va r i a n c e t e s t STATION,MONTH U n c a l c u l a b l e due t o standard d e v i a t i o n of ze r o . Multiple range tests-STATION,MONTH F-rat i o i s not s i g n i f i c a n t at p r o b a b i l i t y 0.05604 Table 27. ANOVA-Saanich I n l e t counts at Saa9, h o r i z o n t a l r e p l i c a t e s taken i n J u l y 1986. Transformed water column t o t a l counts, 135 m 0 1.09161 1.20304 1.23474 140 m 1.66302 1.31419 1 .41136 1 .62325 1 .33935 Depth 145 m 1 .36392 1 .60649 1.60948 1 . 13336 1 .35454 150 m 1 . 17920 1 .04564 1 .24155 A n a l y s i s of v a r i a n c e t a b l e Sum of SOURCE squares DF TOTAL GROUP ERROR 101.489 0.94216 100.548 16 3 13 Mean square 6.34312 0.31405 7.73444 F - r a t i o 24.628 F - r a t i o = e r r MS/gr MS F .05(2)12,3= 14.34 24.628>14.34 t h e r e f o r e , r e j e c t n u l l h y p o t h e s i s , the mean valu e s are s i g n i f i c a n t l y d i f f e r e n t at p=0.05. no Table 28: Copepod faecal pellet production over a 12 hour period. Copepod Period of Total CVs # of pellets # of pellets Total # of Collection Captivity Present (after 6 hours) (after 6 hours) pellets Date (dayis) (after 12 hours) Sept. 9 51 30 8 13 24 Oct. 14 15 29 3 2 5 Table 29: Buoyancy of CVs following their death in experiments 8 and 9. Ten Copepods Twenty Copepods (from Experiment 8) (from Experiment 9) # of Copepods # of Copepods day bottom floating day bottom floating 2.5 10 0 4 13 7 5.5 6 4 5 10 10 7.5 5 5 6 8 12 8.5 4 6 11 5 15 10.5 4 6 12.5 4 6 18 4 6 24 4 6 Table 30: Calculated volume of water filtered through the m S C O R net (46% acceptance). distance volume distance volume hauled filtered hauled filtered (m) K ) (m) (m3) 15 1.73 175 20.18 25 2.88 180 20.76 30 3.46 190 21.91 37 4.27 195 22.49 40 4.61 200 23.06 50 5.77 205 23.64 55 6.34 208 23.99 65 7.50 210 24.22 70 8.07 215 24.79 72 8.30 225 25.95 75 8.65 240 27.68 80 9.23 245 28.25 90 10.37 250 28.83 95 10.96 270 31.34 100 11.53 285 32.87 110 12.69 290 33.44 120 13.84 295 34.02 125 14.42 335 38.63 135 15.57 340 39.21 140 16.15 350 40.36 145 16.72 365 42.09 150 17.30 375 43.25 155 17.87 380 43.82 160 18.45 385 44.40 165 19.03 390 44.98 170 19.61 395 45.55 Table 31: Concentrations of N. plumchrus (CV) and dissolved oxygen from central Saanich Inlet, 1969 (Hoos, 1970). Depth May 21 May 23 May 28 Jun 10 Jun 13 (m) Oxygen Copepods Oxygen Oxygen Copepods (mL L - 1 ) (# m - 3 ) (mL L - 1 ) (mL L " 1 ) (# m" 3 ) 125 0.10 159.2 0.20 0.10 113.5 150 0.06 0 0.05 0.03 0 175 0.00 - 0.00 0.00 -Depth Jul 8 Jul 17 Sep 25 Oct 8 Nov24 (m) Copeods Oxygen Oxygen Copepods Oxygen (# m" 3 ) (mL L " 1 ) (mL L - 1 ) (# m" 3 ) (mL L " 1 ) 125 78.7 0.36 1.38 0.12 0.53 150 0 0.08 0.75 27.0 0.36 175 - 0.00 0.59 - 0.24 Table 32: Dissolved oxygen concentrations (mL L - 1 ) measured in Saanich Inlet in 1969 (see figure 55 for station location). Station Saa3 Depth Jul 28 Depth Sep 16 Depth Oct 28 (m) Oxygen (m) Oxygen (m) Oxygen 0 - 0 - 0 -10 7.75 10 4.88 10 3.60 25 4.17 25 3.45 25 3.46 50 3.60 50 2.91 50 3.63 70 - 70 1.17 70 2.48 80 1.85 80 0.74 80 2.39 90 1.91 90 0.76 90 1.23 100 1.89 100 1.93 100 0.63 110 2.11 110 1.23 110 0.73 120 2.51 120 0.17 120 0.69 150 0.00 150 0.00 150 0.14 175 0.00 175 0.05 175 0.48 200 0.00 200 0.85 200 0.27 Station Saa3.5 Depth Jul 28 Depth Sep 16 Depth Oct 28 H Oxygen (m) Oxygen M Oxygen 0 - 0 - 0 -10 7.48 10 4.54 10 3.61 25 4.28 25 S.76 25 8.68 50 3.54 50 2.83 50 3.34 70 2.20 70 2.18 70 2.22 80 2.19 80 1.32 80 1.77 90 2.76 90 1.15 90 0.92 100 2.48 100 1.80 100 1.03 110 2.64 110 1.85 110 0.64 120 1.81 120 1.57 120 0.43 150 0.15 150 0.80 150 0.34 175 0.00 175 0.65 175 0.43 200 0.00 200 0.88 200 0.48 Station Saa4 Depth Jul 28 Depth Sep 16 Depth Oct 28 (m) Oxygen H Oxygen (m) Oxygen 0 - 0 - 0 -10 7.16 10 4.53 10 3.98 25 4.20 25 3.66 25 3.79 50 S.61 SO S.54 50 3.94 70 2.45 70 1.21 70 S.66 80 2.74 80 1.18 80 2.12 90 2.76 90 1.85 90 1.15 100 2.56 100 1.57 100 0.92 110 2.30 110 1.36 110 1.07 120 2.06 120 0.94 120 0.91 150 1.39 150 1.00 150 0.64 175 0.00 175 0.95 175 0.49 190 0.00 190 0.99 190 0.40 Table 33: Dissolved oxygen concentrations (mL L 1) measured in Saanich Inlet in 1974 (see figure 55 for station location). Station Saa4 Depth Jul 30 Depth Aug 26 Depth Sep 9 (m) Oxygen (m) Oxygen (m) Oxygen 0 9.79 0 - 0 -10 8.65 10 4.05 10 3.59 25 4.97 20 3.51 20 3.10 50 3.89 30 3.47 30 3.89 75 1.57 50 3.46 50 2.58 100 1.95 75 1.05 75 1.84 125 1.73 100 1.56 100 1.33 140 0.87 150 0.91 150 0.89 155 0.12 200 0.36 170 0.09 180 0.01 195 0.02 Table 34. G e l a t i n o u s zooplankton c o l l e c t e d i n September 1985 GELATINOUS Saa9 (0-100 m) SPECIES T o t a l Numbers Number m 1. C l i o n e l i m a c i n a Pteropod 2. L e n s i a b a r y i Siphonophore 3. Dimophyes a r c t i c a Siphonophore 4. Nanomia c a r a Siphonophore 5. Muqqiaea a t l a n t i c a 96 8.3 Siphonophore 6. S a r s i a spp. 16 1.4 7. Limacina h e l i c i n a . Pteropod 8. Aqlantha d i g i t a l e 54 4.7 Hydromedusae 9. Aequorea v i c t o r i a 4 0.3 Hydromedusae 10. P r o b o s c i d a c t y l a f l a v i e i r r a t a 12 1.0 Hydromedusae 11. Hybocodon p r o l i f e r 4 0.3 Hydromedusae 12. Aeqina c i t r e a Hydromedusae 13. Pantachogon h a e c k e l i Hydromedusae 14. P l e u r o b r a c h i a sp. Ctenophore 115 Fitjure 1. The study area. Saanich Inlet, the S t r a i t of Georgia, and Sechelt Inlet (for d e t a i l s see chart no. 3001). 116 Colanoid copepods 6 nouplior stoges NI - NVI 5 copepodite stoges CI - CV v. Adult CVI J > Figure 2. L i f e history stages c h a r a c t e r i s t i c of Neocalanus  plumchrus and the calanoid copepods i n general (top). A l a t e r a l (Pottos l e f t ) and dorsal (bottom right) view of the CV stage (the l a t e r a l view l a taken from Fulton, 1972). Figure 3. S e c h e l t I n l e t and S t r a i t of Georgia a t a t l o n a sampled f o r zooplankton and hydrographic parameters. 118 Figure 4. Northern (Saa9). central ( S B B 3 J . and aouthern (SaaO.8) atatlona l n Saanich I n l e t . The S a t e l l i t e Channel atatlon (Sate) l a Bltuated at the a l l l . Figure 5. The mSCOR net. A messenger i s used to release the b r i d l e s snabling the closure of the net canvas by the t h r o t t l i n g band. 120 a) 5 m in. b) 20 min. c) 20 min. Flour* 6. Bathykymograph raaulta •) baaellna readout to 150 a without C-B nets on tha wir« and the ship atationary, b) the f i r s t horizontal tow to ISO • with three C-B nets on the wire, towed at a speed of 1.5 knots and. c) a r e p l i c a t i o n of the f i r s t horizontal tow. Figure 7. The basic apparatus for the low-oxygen tolerance experiments. The copepods were contained in the teat funnels (Ts and Tb), and the control funnels (Ca and Cb) . Log mean Figure 8. A r e g r e s s i o n of the log mean versus the l o g variance f o r 22 v e r t i c a l haul sample p a i r s . F i g u r e 9. S a l i n i t y d i s t r i b u t i o n (ppt) f o r s t a t i o n Saa9 i n 19B5. Month Jan Fab Mar Apr May Jun Jul Aug Sap Oct Nov Dec F i g u r e 10. Tempera ture d i s t r i b u t i o n ( #C) f o r s t a t i o n Saa9 i n 1985. F i g u r e 11. D e n s i t y d i s t r i b u t i o n (s igma-t) f o r s t a t i o n Saa9 i n 1985. Figure 12. Dissolved oxygen distribution (mL L-l) for station Sea9 in 1985. F i g u r e 13. S a l i n i t y d i s t r i b u t i o n (ppt) f o r s t a t i o n Saa9 i n 1986. F i g u r e 14. Temperature d i s t r i b u t i o n («C) f o r s t a t i o n Saa9 i n 1986. F i g u r e 15. D e n s i t y d i s t r i b u t i o n (s igma-t) f o r s t a t i o n Saa9 i n 1986. Month Figure 16. Dissolved oxygen distribution (mL L-l) for station Sea9 in 19B6. Oxygen (mL L-l) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r x 800-1 1 6 8 10 Copepod Concentration (# m-3) Figure 17. Copepod concentratione (aolid area) and dissolved oxygen levels (dashed line) at station S B B 3 . August 19B5. The 'x' designates the depths at which N. plumchrus was not found. Oxygen (mL L-l) SO • i - - 1 r " " I ~ T 1 1 1 T 1 1 • 1 1 1 1 - — 9 x f 0 2 4 6 a 10 Copepod Concentration (# m-3) Figure 18. Copepod concentrations (eolid area) and dissolved oxygen levels (daehed line) at station Saa3. August 1986. The *x' designates the depth at which N. plumchrua was not found. Month Jan Fab Mar Apr Hay Jun Jul Aug Sap Oct Nov Doc F i g u r e 20. Tempera ture d i s t r i b u t i o n [°0 f o r s t a t i o n SaaO.B i n 1985. Month Month Month Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 200 Figure 23. Salinity distribution (ppt) for station SaaO.8 in 1986. Month Figure 24. Tempereture distribution (°C) for station Seed.8 in 1986. Figura 25. Density dletribution (eigma-t) for atetion SaaO.S in 1986. Figure 26. Dissolved oxygen distribution (mL L-l) for stetion SaaO.8 in 1986. Month Figure 30. Dissolved oxygen distribution (mL L-i) for stetions 61545 and 61748 in 1985. Month Month Fab Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 32. Tempereture distribution (°C) for station 61545 in 1986. Month Figure 34. Dissolved oxygen distribution (mL L-l) for station 61545 in 1966. Oxygen (mL L-l) Temperature (°C) F i g u r e 3 5 . H y d r o g r a p h i c pa rameter s c o l l e c t e d a t s t a t i o n S c i . November 1985: oxygen (x). d e n s i t y (O). t e m p e r a t u r e (o). and s a l i n i t y (A). CD Oxygen (mL L-l) Temperature (°C) 0 -SO -« 100 -r *> a 150 -800 -250 -IB 18 SO 4J a a a 4 6 8 10 IS 14 0 - • • • A A ) A 50 ) A () A 100 - 1 I A C > A ISO - < A ( A SOO - < ) A < > A S50 i . - X . . • _1 L . SS 24 Density (slgms t) SS 24 SB SB SO Ssllnlty (ppt) F i g u r e 36 . H y d r o g r a p h i c pa rameter s c o l l e c t e d a t s t a t i o n S c i . F e b r u a r y 1986: oxygen (x). d e n s i t y fo). t e m p e r a t u r e to), and s a l i n i t y (A). 38 Oxyg«n (mL L-l) Temperature (°C) 10 7 9 11 13 15 17 19 Si 0 F 50 h e a a a 100 150 h 200 h 250 h 300 r c *> a a a 50 100 150 200 r 250 h n 1 r r 1 1 1 A A A A A 3 0 0 Li i i i i_ 13 15 17 19 21 23 15 17 19 21 23 25 27 29 Density (sigme t) Salinity (ppt) F i g u r e 3 7 . H y d r o g r a p h i c pa rameter s c o l l e c t e d a t s t e t i o n Sc2. August 1986; oxygen (x). d e n s i t y (O). t e m p e r a t u r e (O). and s a l i n i t y (A). o Oxygen (mL L-i) Temperature (°C) Density (sigma t) Salinity (ppt) F i g u r e 38 . H y d r o g r a p h i c pa remete r s c o l l e c t e d e t s t a t i o n Sc2a. August tn 1986: oxygen (X). d e n s i t y (O). t e m p e r e t u r e (O). end s a l i n i t y [A). ~* cc oo C o p e p o d Densi ty i : r i : i : i : L 0 40 0 <1 m~ 3 OOm" 3 ( m - 3 ) 0 CIV • CV &. CVI Figure 39. Vertical distribution of Neocalanus plumchrus sampled from July 1985 through September 1986 (counterclockwise) at stations 61545 and 61748 (the bar perpendicular to the density line demarcates a separate vertical haul). f I 1 I I » 1 I I I I I I I I AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP Months (1985-1986) F i g u r e 40 . Copepod c o n c e n t r a t i o n s (CIV-CVI) c o l l e c t e d i n t he S t r a i t o f G e o r g i a i n 1985 and 1986. The BOX c o n f i d e n c e i n t e r v a l s e r e shown f o r A p r i l t h r o u g h Augu s t . MAY JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN J U L AUG SEP Months (1983-1966) F i g u r e 4 1 . Copepod c o n c e n t r a t i o n s (CIV-CVI) c o l l e c t e d l n S a a n i c h I n l e t and S a t e l l i t e Chenne l i n 1985 end 1986. The 80% c o n f i d e n c e i n t e r v a l s e r e shown f o r r e p l i c e t e samples c o l l e c t e d e t SaaO.8 from Mey t o September w i t h t h e e x c e p t i o n o f Augus t i n wh ich the r e p l i c e t e samples were c o l l e c t e d e t Saa3. C D 03 Copepod Density 0 4 0 <1 m~3 (m - 3) CIV H CV & CVI Figure 42. Vertical distribution of Neocalanus plumchrus sampled from May 1985 through September 1986 (counterclockwise) at station Sate in Satellite Channel. 1 5 6 CO Copepod Density 0 4 0 <1 m-3 (m-3) 0 CIV • CV & CVI Figure 43. Vertical diatribution of Neocalanua pluwchrua sampled from May 19BS through September 19B6 (counterclockwise) at atationa 8aa3 in Saanich Inlet (the bar perpendicular to the denaity line demarcates a separate vertical haul). 1 5 7 CO 00 C o p e p o d Densi ty 0 4 0 <1 m - 3 ( m - 3 ) £2 CIV H CV & CVI Figure 44. Vertical distribution of Neocalanus plumchrus sampled from September 1985 through September 1986 (counterclockwise) at station 8aa0.8 in Saanich Inlet. cc Copepod Density 0 4 0 <1 m - 3 ( m ~ 3 ) 0 CIV • CV Sc CVI Figure 45. Vertical distribution of Neocalanus plumchrus sampled from September 19B5 through September 19B6 (counterclockwiae) st station 8aa9 in Saanich Inlet. Oxygen (mL L-l) 6 7 8 9 10 50 • 100 150 200 i i i i — i r 1 1 '" " I"1 9 X " " " " 1 <D 1 t $ 0 1 2 3 4 Copepod Concentrations (# m-3) Figure 46. Copepod concentratlona (aolid area) and dissolved oxygen levela (dashed line) at atatlon SaeO.8. June 1986. The 'x' designates the depths at which N. plumchrus waa not found. Oxygen (mL L-l) 0 • 40 • BO • ISO 160 Copepod Concentrations (# m-3) Figure 47. Copepod concentretions (solid area) end dissolved oxygen levels (dashed line) et station Saa9. July 1966. The 'x' designetes ths depth et which N. plumchrus wss not found. 161 C O C O C o p e p o d Dens i ty 0 4 0 <1 m - 3 (m - 3) 0 CN • CV & CVI Figure 48. Vertical distribution of Neocalanus plumchrus sampled from November 1985 and February 1986 (counterclockwise) at station Sci in Sechelt Inlet. In August 19B6 the copepods were collected at station 8c la. Figure 49. Vertical distribution of Neocalanus plumchrus sampled in August 1986 at otatlona Sc2 and 9c2a in Sechelt Inlet. •ays in Captivity F i g u r e 50 . M o r t a l i t y of s t a r v e d v e r s u s f e d copepods c o l l e c t e d O c t o b e r 14. 1986. 2 4 6 Oxygen (mL L - l ) F i g u r e 51 . P e r c e n t m o r t a l i t y o f CVs exposed to d i f f e r e n t oxygen c o n c e n t r a t i o n s . Note the v a r i a t i o n s i n the t ime of yee r the copepods were c o l l e c t e d (numbers i n d i c a t e t h e days h e l d i n c a p t i v i t y p r i o r t o e x p e r i m e n t a t i o n ) . ^ S e ./'Oc Se . A J l (Seen) Oxygen (mL L - l ) • . 4 7 - . 4 8 . 5 6 - . 3 4 + . 5 9 - . 6 2 - . 6 2 X . 7 1 - . 6 9 O . 8 3 - . 8 7 V . 9 4 - . 9 5 - . 9 2 • 2 . 1 1 - 2 . 0 8 - 2 . 0 2 20 40 60 80 100 120 Number o f Deys In C a p t i v i t y F i g u r e 52. C a p t i v i t y p e r i o d and p e r c e n t m o r t a l i t y o f CVs s u b j e c t e d t o low oxygen t o l e r a n c e t e s t s . Mean oxygen c o n c e n t r e t i o n f o r each e x p e r i m e n t i e a r r a n g e d a c c o r d i n g to i t a o c c u r r e n c e i n t he l e g e n d . 1 6 6 o Number of Days ln Captivity Figure 53. Expected reaults of the low oxygen tolerance experiments. 167 F i g u r e 54. The h y p o t h e s i z e d d i s t r i b u t i o n o f N e o c a l a n u s p l umchru s p r i o r t o , and d u r i n g the deep Meter r e n e w a l i n 19B5; ba sed on b i o l o g i c a l d a t a and the oxygen reg ime on Augus t 7 t h (a) and September 17th (c) . F i g u r e 5 5 . H y d r o g r a p h i c s t a t i o n s (Saa4. Saa3.5 . and Saa3) and t h e z o o p l a n k t o n h a u l s t a t i o n ( S tn .E ) sampled l n 1969 and 1974. 169 REFERENCES A l l d r e d g e , A.L., B.H. Robison, A. Fleminger, J . J . T o r r e s , J.M. King and W.M. Hammer. 1984. D i r e c t sampling and i n s i t u o b s e r v a t i o n of a p e r s i s t e n t copepod aggregation i n the mesopelagic zone of the Santa Barbara B a s i n . Mar. B i o l . 80: 75-81. Anderson, J . J . , and A.H. Devol. 1973. Deep water renewal i n Saanich I n l e t , an i n t e r m i t t e n t l y anoxic b a s i n . E s t u a r i n e C o a s t a l Mar. S c i . 1:1-10. 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 Georgia. M.Sc. T h e s i s . Univ. B r i t i s h Columbia. 128 p. Burd, B.J., and R.O. B r i n k h u r s t . 1984. The d i s t r i b u t i o n of the G a l a t h e i d Crab Munida q u a d r i s p i n a (Benedict 1902) i n r e l a t i o n to oxygen c o n c e n t r a t i o n s i n B r i t i s h Columbia f j o r d s . J . Exp. Mar. B i o l . E c o l . 81: 1-20. C a r r i t t , D.E. and J.H. Carpenter. 1966. Comparison and e v a l u a t i o n of c u r r e n t l y employed m o d i f i c a t i o n s of the Winkler Method f o r determining d i s s o l v e d oxygen i n seawater; A NASCO Report. J . Mar. Res. 24: 286-318. C h i l d r e s s , J . J . 1975. The r e s p i r a t o r y r a t e s of midwater crustaceans as a f u n c t i o n of depth of occurrence and r e l a t i o n to the oxygen minimum l a y e r o f f Southern C a l i f o r n i a . Comp. Biochem. P h y s i o l . 50A: 787-799. Cowen, M.B. 1982. Overwi n t e r i n g s t r a t e g i e s of the C a l a n o i d Copepod Calanus plumchrus i n a p e r i o d i c a l l y anoxic B r i t i s h Columbia F j o r d . M.Sc. Univ. of V i c t o r i a . 105 pp. Dagg, M.J., and W.E. Walser. 1987. I n g e s t i o n , gut passage, and eg e s t i o n by the copepod Neocalanus plumchrus i n the l a b o r a t o r y and i n the s u b a r c t i c P a c i f i c Ocean. Limnol. Oceanogr. 32: 178-188. Devol, A.H. 1981. V e r t i c a l d i s t r i b u t i o n of zooplankton r e s p i r a t i o n i n r e l a t i o n t o the inten s e oxygen minimum zones i n two B r i t i s h Columbia f j o r d s . J . of Plank. Res. 3: 593-602. Downing, J.A., M. Perusse, Y. F r e n e t t e . 1987. E f f e c t of 170 i n t e r r e p l i c a t e v a r i a n c e on zooplankton sampling design and data a n a l y s i s . Limnol. Oceanogr. 32: 673-680. Elgmork, K. and J.P. N i l s s e n . 1978. Equivalence of copepod and i n s e c t diapause. Verh. I n t e r n a t . V e r e i n . Limnol. 20: 2511-2517. Evans, M.S. and D.W. S e l l . 1983. Zooplankton sampling s t r a t e g i e s f o r environmental s t u d i e s . H y d r o b i o l o g i a 99: 215-223. F i s h , A.G. 1968. F i e l d o b s e r v a t i o n s i n an o x y g c l i n e i n r e l a t i o n to l a b o r a t o r y d e t e r m i n a t i o n s of oxygen requirements i n some s p e c i e s of marine zooplankton. Ph.D. T h e s i s , Univ. of B r i t i s h Columbia. 75 p. F r o s t , B.W., M.R. Landry, and R.P. H a s s e t t . 1983. Feeding behaviour of l a r g e c a l a n o i d copepods Neocalanus c r i s t a t u s and N. plumchrus from the s u b a r c t i c P a c i f i c Ocean. Deep-Sea Res. 30(1): 1-13. F u l t o n , J.D. 1972. Keys and r e f e r e n c e s to the marine Copepoda of B r i t i s h Columbia. F i s h . Res. Board Can. Tech. Rep. 313: 1-63. F u l t o n , J.D. 1973. Some aspects 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 . F i s h . Res. Bd. Can. 30: 811-815. Gardner, G.A. 1972. The d i s t r i b u t i o n of the l i f e h i s t o r y stages of Calanus plumchrus Marukawa (Copepoda: Calanoida) i n the S t r a i t of Georgia. M.Sc. T h e s i s , Univ. B r i t i s h Columbia, 55 p. Gardner, G.A. 1977. A n a l y s i s of zooplankton p o p u l a t i o n f l u c t u a t i o n s i n the S t r a i t of Georgia, B r i t i s h Columbia. J . F i s h . Res. Bd. Can. 34(8): 1196- 1206. Gardner, G.A., and I. Szabo. 1982. B r i t i s h Columbia p e l a g i c marine Copepoda: an i d e n t i f i c a t i o n manual and annotated b i b l i o g r a p h y . Can. Spec. Publ. F i s h . Aquat. S c i . No. 62: 532 p. Gehringer, J.W. and W. Aron. 1968. F i e l d t e c h niques. IN: Zooplankton Sampling, UNESCO Monographs on Oceanographic Methodology. 2: 87-104. 171 Geyer, W.R., and G.A. Cannon. 1982. S i l l Processes r e l a t e d to deep water renewal i n a f j o r d . J . Geophys. Res. 87: 7985-7996. Hagerman, L. 1976. The r e s p i r a t i o n d u r i n g the moult c y c l e of Crangon v u l g a r i s ( F a b r . ) ( C r u s t a c e a . N a t a n t i a ) . O p h e l i a . 15:15-21. 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 . Aqu. S c i . 40(7): 1064-1094. Hart, J.L. 1973. P a c i f i c F i s h e s of Canada. F i s h Res. Bd. Can. B u l l e t i n 180. Herlinveaux, R.H. 1962. Oceanography of Saanich I n l e t i n Vancouver I s l a n d , B r i t i s h Columbia. J . F i s h . Res. Bd. Can. 19: 1-37. Hoos, R.A.W. 1970. D i s t r i b u t i o n and p h y s i o l o g y of zooplankton i n an oxygen minimum l a y e r . M.Sc. T h e s i s . Univ. of V i c t o r i a . 113 pp. IOUBC Data Reports. 1969, 1974, 1983, 1985, 1986. U n i v e r s i t y of B r i t i s h Columbia Data Reports. Nos. 30, 37, 52, 54, 55. Judkins, D.C. 1980. V e r t i c a l d i s t r i b u t i o n of zooplankton i n r e l a t i o n to the oxygen minimum o f f Peru. Deep-Sea Res. 27A: 475-487. K o e l l e r , P.A. 1974. Taxonomy, d i s t r i b u t i o n and a s p e c t s of the b i o l o g y of some d e e p - l i v i n g copepods i n B.C. i n l e t s and adjacent water. M.Sc. T h e s i s . Univ. of V i c t o r i a . 128 pp. LeBrasseur, R.J., W.E. Barraclough, O.D. Kennedy, and T.R. Parsons. 1969. P r o d u c t i o n s t u d i e s i n the S t r a i t of G e o r g i a . Part I I I . Observations on the food of l a r v a l and j u v e n i l e f i s h i n the F r a s e r R i v e r Plume, February to May, 1967. J . Exp. Mar. B i o l . E c o l . 3: 51-61. LeBlond, P.H. 1983. The S t r a i t of G e o r g i a : f u n c t i o n a l anatomy of a c o a s t a l sea. Can. J . F i s h . Aquat. S c i . 40: 1033-1063. Lee, R.F., J.C. Nevenzel and F.-A. P a f f e n h o f e r . 1972. The 172 presence of wax e s t e r s i n marine p l a n k t o n i c Copepods. Naturwissenschaften. 59: 406-411. Longhurst, A.R. 1967. V e r t i c a l d i s t r i b u t i o n of zooplankton i n r e l a t i o n to the E a s t e r n P a c i f i c oxygen minimum. Deep Sea Res. 14: 51-63. Lu, X., W.K. Johnson, and C.S. Wong. 1986. Seasonal replenishment of mercury i n a c o a s t a l f j o r d by i t s i n t e r m i t t e n t a n o x i c i t y . Marine P o l l u t i o n B u l l . 17: 263-267. Mackie, G.O. 1985. Midwater macroplankton of B r i t i s h Columbia s t u d i e d by submersible P i s c e s IV. J . Plankton Res. 7: 753-777. Mackie, G.O. and C.E. M i l l s . 1983. Use of the P i s c e s IV submersible f o r zooplankton s t u d i e s i n c o a s t a l waters of B r i t i s h Columbia. Can. J . F i s h . Aquat. S c i . 40: 763-776. Mansingh, A. 1971. P h y s i o l o g i c a l c l a s s i f i c a t i o n of dormancies i n i n s e c t s . Can. Entomol. 103: 983-1009. Mason, J.C. and A.C. P h i l l i p s . B i l o g y of the b a t h y l a g i d f i s h , L e u r o g l o s s u s s c h m i d t i , i n the S t r a i t of Georgia, B r i t i s h Columbia. Can. J . F i s h . Aquat. S c i . 42: 1144-1153. M i l l e r , C.B., B.W. F r o s t , H.P. B a t c h e l d e r , M.J. demons, and R.E. Conway. 1984. L i f e h i s t o r i e s of l a r g e , g r a z i n g copepods i n a S u b a r c t i c Ocean Gyre: Neocalanus plumchrus, Neocalanus c r i s t a t u s , and Eucalanus b u n q i i i n the Northeast P a c i f i c . Prog.Oceanog. 13: 201-243. Pacquette, R.G., and H.F. F r o l a n d e r . 1957. Improvements i n the C l a r k e - Bumpus plankton sampler. J . Cons. I n t e r n a t . E x p l o r . Mer. 22: 284-288. Paranjape, M.A. 1967. M o l t i n g and R e s p i r a t i o n of E u p h a u s i i d s . J . F i s h . Res. Bd. Can. 24: 1229-1240. Passano, L.M. 1960. M o l t i n g and i t s c o n t r o l . IN: The P h y s i o l o g y of C r u s t a c e a . Ed. by Waterman, T.H. V o l . 1, pp 473-536. P i c k a r d , G.L. 1961. Oceanographic f e a t u r e s of the i n l e t s of the B r i t i s h Columbia mainland c o a s t . J . F i s h . Res. Bd. Can. 173 18: 907-999. P i c k a r d , G.L., and W.J. Emery. 1982. D e s c r i p t i v e P h y s i c a l Oceanography. 4th E d i t i o n . Pergamon Press, Toronto. 249 pp. Raymont, J.E.G. 1983. Plankton and P r o d u c t i v i t y i n the Oceans. 2nd E d i t i o n . Pergamon Press, Toronto. Regan, L. 1963. F i e l d t r i a l s with the Clarke-Bumpus plankton sampler. IOUBC Manuscript Report, No. 16. Schumacher, J.D., C A . Pearson, R.L. C h a r n e l l , and N.P. L a i r d . 1978. Regional response to f o r c i n g i n Southern S t r a i t of Georgia. E s t u a r i n e C o a s t a l Mar. S c i . 7: 79-91. S t a n i e r , R.Y., E.A. Adelberg, J.L. Ingraham, and M.L. Wheelis. 1979. I n t r o d u c t i o n to the M i c r o b i a l World. P r e n t i c e - H a l l , New J e r s e y . 468 pp. S t u c c h i , D.J., and L.F. Giovando. 1984. Deep water renewal i n Saanich I n l e t , B.C. IN: Proceedings of a M u l t i d i s c i p l i n a r y Symposium on Saanich I n l e t , 2nd February, 1983. Ed. by J u n i p e r , S.K. and R.O. B r i n k h u r s t . Can. Tech. Rep. Hydrogr. Ocean S c i . : No.38: 104 pp. T a y l o r , L.R. 1961. Aggregation, v a r i a n c e and the mean. Nature. 189: 732-735. Theede, H. 1973. Comparative s t u d i e s on the i n f l u e n c e of oxygen d e f i c i e n c y and hydrogen s u l p h i d e on marine bottom i n v e r t e b r a t e s . Netherlands J . of Sea Res. 7: 244-252. Waldichuck, 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 . F i s h . Res. Bd. Can. 14: 321-486. Yentsch, C.S., and A.C. Duxbury. 1956. Some of the f a c t o r s a f f e c t i n g the c a l i b r a t i o n number of the Clarke-Bumpus q u a n t i t a t i v e plankton sampler. Limnol. Oceanogr. 1: 268-273. 174 APPENDIX A E s t i m a t i o n of the volume of water in t r o d u c e d i n t o Saanich I n l e t d u r i n g the renewal i n 1985 between August 7 and September 17 (Paul LeBlond, p e r s . comm.). V,= volume of i n t r u d i n g water V 2 = volume of water below 150 m V 3 = volume of mixed water C,= c o n c e n t r a t i o n of 0 2 i n the i n t r u d i n g water C 2= 0 2 c o n c e n t r a t i o n below 150 m, August 7 C 3= 0 2 c o n c e n t r a t i o n of mixed water below 150 m, September 17 unknown of i n t e r e s t V 2 = 13.0 x 10 8 m3 (estimate from Anderson & Devol, 1973) V 3= ? C,= 2.0 mL L" 1 (estimate based on the decrease i n 0 2 content of renewed water i n the S t r a i t of Georgia) C 2 = 0.02 mL L " 1 (approximately 22% of the water below 150 m co n t a i n e d 0.10 mL L" 1) C 3= 0.38 mL L" 1 (the average 0 2 c o n c e n t r a t i o n below 150 m) V , + V 2 = V 3 C,V, + C 2 V 2 = C 3 V 3 + C 2 V 2 = C 3 ( V , + V 2 ) C,V, + C 2 V 2 = C 3 V , + C 3 V 2 c,v, - C 3 V i = C 3 V 2 - C 2 V 2 v^c,- c3)= v 2 (c 3 - c 2) Yi = (c 3- c 2) v 2 (c,- c 3) V , = 0.38 mL L ' 1 - 0.02 mL L- 1 x 13 x 10 8 m3 2.0 mL L " 1 - 0.38 mL L" 1 V , = 2.89 x 10 8 m3 (volume of i n t r u d i n g water i n 1985) Estimate of volume of i n t r u d i n g water (V^ ) i n 1969, 4.3 x 10 8 m3 ( + 0.6 x 10 8) - (Anderson & Devol, 1973) C a l c u l a t i o n of an e q u i v a l e n t volume of o u t f l o w i n g water to balance the i n f l o w . length= 12 km (assuming the m a j o r i t y of copepods are found at & Saa9) width= 2.5 km (mean value) thickness= 10m 10 m x 2500 m x 12,000 m = 3 x 10 8 m3 

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