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Benthic algal ecology and primary pathways of energy flow on the Squamish River Delta, British Columbia Pomeroy, William M. 1977

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BENTHIC ALGAL ECOLOGY AND PRIMARY PATHWAYS OP ENERGY FLOW ON THE SQUAMISH RIVER DELTA, BRITISH COLUMBIA by WILLIAM MARTIN POMEROY B. S c . , U n i v e r s i t y o f V i c t o r i a , V i c t o r i a , B.C., 1972 M. S c . , U n i v e r s i t y o f M a n i t o b a , W i n n i p e g , Man., 197^ A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF BOTANY We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA October, 1977 © W i l l i a m M a r t i n Pomeroy, 1977 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of Brit ish 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 representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Bo / /9/^] The University of Brit ish Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date f?C<r. /T77 i i ABSTRACT Benthic a l g a l ecology and primary pathways of energy flow were considered on the Squamish River delta at the head of Howe Sound, a fjord-type estuary. The study elucidated the structure and function of major autotro-phic components of the estuarine ecosystem. Benthic algae were investigated with regard to species compos-i t i o n and d i s t r i b u t i o n and the capacity for energy conversion, input to the system and storage. Compari-sons were made with ex i s t i n g information on the vascular plant component of the ecosystem. The benthic a l g a l community was studied by regular f i e l d sampling of major macroalgae and microalgal associ-ations with a monitoring of physical-chemical environ-mental factors. Presence of an alga i n the estuary was a function of i t s osmoregulatory c a p a b i l i t i e s . Establishment and temporal-spatial d i s t r i b u t i o n patterns were controlled by substrate-habitat preference and a v a i l a b i l i t y and the in t e r a c t i o n of l i g h t , interspecies competition, desiccation, temperature and s a l i n i t y , l i g h t being of greatest importance. Carex lyngbyei Hornem., the dominant vascular plant, had a s i g n i f i c a n t effect on d i s t r i b u t i o n of benthic algae through l i g h t r e s t r i c t i o n during Its summer growth period and action as a substrate during the winter. Total species diver-s i t y , biomass and d i s t r i b u t i o n a l area of benthic algae were greatest at the l a t t e r period. i i i The e f f e c t of ecosystem structure on function was investigated by analysis of energy flux through major benthic a l g a l producers. Comparisons were made of the t o t a l amount of energy input attributable to benthic algae and vascular plants. The importance of an a l g a l _ p producer to energy flux-m was a function of either high primary productivity, photosynthetic e f f i c i e n c y and c a l o r i c content, or i n the case of diatom dominated micro-a l g a l associations, high c a l o r i c content alone. D i s t r i -bution, r e f l e c t i n g the presence of suitable substrate-habitat, modified t h i s pattern. Macroalgae having high energy input*m (Monoetroma oxyapermum (Kutz.) Doty, P y l a i e l l a littoral-is (Lyngb.) K j e l l . ) were of minimum importance to t o t a l energy input. Two microalgal associ-ations (Association E, diatom dominated, Association G, U l o t h r i x f l a o c a ( D i l l . ) Thur. dominated), each with low energy input-m but with wide d i s t r i b u t i o n and high photosynthetic e f f i c i e n c y and c a l o r i c content contributed a t o t a l of 8H% of available energy attributable to benthic algae. Benthic algae account for a maximum of ca. 7% of t o t a l energy input to the delta ecosystem compared to ca. 9 0 $ by vascular plants and 3% by addition of organic matter. The majority of energy for the d e t r i t a l based ecosystem comes from vascular plants and becomes a v a i l -able af t e r a lag period allowing decomposition. Benthic algae are s i g n i f i c a n t to the ecosystem as a readily i v a v a i l a b l e , continually present energy source requiring l i t t l e or no breakdown f o r u t i l i z a t i o n and not f o r t o t a l energy input. Energy i s available as either dissolved or p a r t i c -ulate organic matter. Of the l a t t e r , ca. 49$ i s removed to the estuary, 33% incorporated into the sediments of the delta and 18$ used by consumers i n the d e l t a eco-system. V TABLE OF CONTENTS Page ABSTRACT i i LIST OP TABLES v i i i LIST OP FIGURES x i LIST OP APPENDICES x i v ACKNOWLEDGEMENTS x v i INTRODUCTION 1 STUDY AREA 4 MATERIALS AND METHODS 11 I . P h y s i c a l - C h e m i c a l F a c t o r s 11 A. S a l i n i t y , t e m p e r a t u r e , p r e c i p i t a t i o n , l i g h t 11 B. A l k a l i n i t y , pH, n u t r i e n t s 13 C. Sediment and o r g a n i c d e p o s i t i o n p a t t e r n s I 1* D. T i d a l c r e e k f l o w r a t e s 15 I I . B i o l o g i c a l F a c t o r s 16 A. D i s t r i b u t i o n (coverage a r e a ) and biomass 16 B. P r i m a r y p r o d u c t i o n 16 Carbon-l*! method 17 D i s s o l v e d oxygen method 21 C. Removal, d e p o s i t i o n o f p a r t i c u l a t e o r g a n i c m a t t e r (POM) 22 D. C a l o r i c e q u i v a l e n t s 25 E. A l g a l , p l a n t and d e t r i t u s u t i l i z a t i o n by amphipods 26 F i e l d s t u d i e s 27 L a b o r a t o r y s t u d i e s < 27 F a t t y a c i d s p e c t r a comparison 28 I I I . A n a l y s i s o f F a c t o r s I n f l u e n c i n g P r i m a r y P r o d u c t i o n 29 v i RESULTS 30 I. Physical-Chemical Factors 30 A. S a l i n i t y , temperature, l i g h t 30 B. pH, nutrients 34 C. Sediment and organic deposition patterns 36 D. T i d a l creek fiow rates 38 I I . B i o l o g i c a l Factors . . 40 A. Species composition and d i s t r i b u t i o n . . . 40 B. Biomass and production 49 14 C. Comparison of C and dissolved oxygen primary production estimates.... 58 D. Dissolved organic material (DOM) exuded during production 6 l E. Addition and removal of pa r t i c u l a t e organic material (POM) 6 l Addition . 6 l Removal 64 F. Caloric equivalents 69 G. Benthic algae, vascular plant, d e t r i -tus u t i l i z a t i o n by amphipods , 72 I I I . S t a t i s t i c a l Analysis of Factors I n f l u -encing Primary Production 77 DISCUSSION 79 I. Ecosystem Structure 79 I I . Ecosystem Function.. 92 A. Energy sources, conversion and storage 95 Energy sources 95 Energy conversion, input and storage 98 1) Vascular plants 98 2) Benthic algae 102 3) Seasonal v a r i a t i o n i n energy conversion and storage 108 v i i B. Annual energy flux and general ecosystem function 110 Sand/mud f l a t habitat 112 Carex marshland I l k I I I . The Squamish River Delta as a Productive, Energy Rich Ecosystem 12*1 LITERATURE CITED 131 APPENDICES 144 v i i i LIST OF TABLES T a b l e Page 1 . P h o t o s y n t h e t i c a l l y a v a i l a b l e r a d i a t i o n r e a c h i n g t h e study a r e a 31 2 . Shading o f t h e d e l t a s u r f a c e by a t t a c h e d v a s c u l a r p l a n t s . L i g h t a t t e n u a t i o n as p e r c e n t i n c i d e n t r a d i a t i o n 33 3 . N u t r i e n t c o n c e n t r a t i o n s ( A g - a t • l ~ 1 ) i i n s u r f a c e w a t e r s s u r r o u n d i n g t h e d e l t a (sam-p l e s t a k e n at h i g h t i d e ) 37 4 . Major a l g a l s p e c i e s w i t h t h e i r p r e f e r r e d s u b s t r a t e and l o c a t i o n on t h e d e l t a 41 5 . Appearance, c o m p o s i t i o n , and d i s t r i b u t i o n o f m u l t i s p e c i f i c m i c r o a l g a l a s s o c i a t i o n s . . 46 6. S e a s o n a l o c c u r r e n c e o f macroalgae and m i c r o -a l g a l a s s o c i a t i o n s 52 7 . Maximum biomass v a l u e s f o r macroalgae and m i c r o a l g a l a s s o c i a t i o n s 52 8 . Net p r o d u c t i v i t y maximum and minimum r e c o r d e d f o r macroalgae and m i c r o a l g a l a s s o c i a t i o n s 54 9 . Monthly C net p r o d u c t i o n e s t i m a t e s (g C x 10 ) f o r macroalgae and m i c r o a l g a l a s s o c i a -t i o n s p e r d i s t r i b u t i o n (.coverage; a r e a , c o r r e c t e d f o r coverage-exposure t i m e 56 i x 10. Net p r i m a r y p r o d u c t i o n o f macroalgae and m i c r o a l g a e a s s o c i a t i o n s on t h e d e l t a (g C-m~ 2-day~ 1) 59 14 11. C p r o d u c t i o n as p e r c e n t oxygen p r o d u c t i o n (averages o f 10 d e t e r m i n a t i o n s ) 60 12. O r g a n i c e x u d a t i o n as p e r c e n t t o t a l net p r i m a r y p r o d u c t i o n measured by t h e " C method . . 62 13. A d d i t i o n o f p a r t i c u l a t e o r g a n i c m a t t e r t o t h e d e l t a (mg C*m ) (mean o f 4 s a m p l i n g s i t e s i n each a r e a , s a m p l i n g p e r i o d o v e r 1 t i d a l c y c l e ) 65 14. P a r t i c u l a t e o r g a n i c m a t t e r Removed from t h e d e l t a by Snag and P i l e c r e e k s (mg C - l - 1 ) a t h i g h and low wat e r l e v e l s 68 —2 15. P a r t i c u l a t e o r g a n i c m a t t e r (mg C.m ' f l o o d tide""*") removed from t h e major h a b i t a t t y p e s on t h e d e l t a 70 16. C a l o r i c e q u i v a l e n t s f o r a l g a e , s e d i m e n t s , d e t r i t u s and p a r t i c u l a t e o r g a n i c m a t t e r . . . . 71 17. R e s u l t s o f a n a l y s i s u s i n g a 2 x 2 c o n t i n g e n c y t a b l e showing r e l a t i o n s h i p s o f macroalgae 2 and amphipods i n a 30 x 30 m g r i d on t h e marshland a t low t i d e ( T a b u l a t e d = 3.84 a t P0.05 ) 7 3 18. Cover and f e e d i n g p r e f e r e n c e shown by amphi-pods t e s t e d i n t h e l a b o r a t o r y ( t o t a l o f 300 a d u l t s a n d j u v e n i l e amphipods - 15 t r i a l s o f 20 each) ) 74 X 19. Patty acid analysis of selected food sources and amphipods fed on them 76 20. S t a t i s t i c a l analysis of primary produc-t i o n data using stepwise multiple regression (p = 0.05). Dependant variable, = net production; independent variables = s a l i n i t y , l i g h t , temperature, n i t r a t e , phosphate and ammonia.... 78 21. Total energy input (gross production), storage (net productionaas DOM, POM), and losses (respiration) for benthic a l g a l producers i n f a l l , winter, spring, and summer as keal x 10 *mo 'study area I l l 22. Annual energy flux for sand/mud f l a t s .,' 2 &area = 15875 ni ) and sedge marshlands (area = 111125 m2).... 113 23. Comparison of net production (energy -2 -1 storage) as g C*m «yr for Carex l y n g b y e i and vascular plants of other marsh areas 128 24. Comparison of net production (energy —2 1 storage) as g C-m •yr"' for diatom-dominated microalgal associations i n estuarine and marine habitats 130 x i LIST OP FIGURES F i g u r e Page 1. S o u t h e r n c o a s t o f B r i t i s h Columbia showing t h e l o c a t i o n o f Howe Sound w i t h t h e Squamish d e l t a a t t h e head 5 2 . Squamish R i v e r e s t u a r y , B r i t i s h Columbia showing p h y s i o g r a p h i c d e t a i l s o f t h e d e l t a . . 6 3 . D e t a i l e d map o f C e n t r a l d e l t a showing s a m p l i n g s t a t i o n s 12 4 . Diagram o f cage used f o r s t u d i e s o f p a r t i c -u l a t e o r g a n i c removal i n p l a c e on t h e d e l t a 23 L i g h t a t t e n u a t i o n w i t h depth I n w a t e r column a d j a c e n t t o t h e d e l t a ( d a t a appear i n Appendix I ) 32 6»a, b, c. A i r t e m p e r a t u r e , p p t . , w a t e r temp-e r a t u r e , pH and s a l i n i t y June 1 9 7 4-August 1975 (Data appear i n Appendix I I ) 35 7 . S e a s o n a l p a t t e r n s o f s e d i m e n t a t i o n and sediment o r g a n i c c o n t e n t ( s i t e d e s c r i p t i o n s and d a t a appear i n Appendix IV) 39 8 , a, b. Macroalgae showing g r o s s appearance o f P y l a i e l l a l i t t o v a l i s (a) and Enteromorpha minima (b) 44 c, d. M i c r o a l g a l a s s o c i a t i o n s showing g r o s s appearance o f (c) A s s o c i a t i o n D and (d) A s s o c i a t i o n F 44 x i i 9. T o t a l coverage a r e a and a l g a l biomass 48 10. D i s t r i b u t i o n o f b e n t h i c a l g a e on t h e d e l t a i n A) f a l l ( S eptember), B) w i n t e r (December), C) s p r i n g (March) and D) summer (June) . •••• 50 11. P a r t i c u l a t e o r g a n i c m a t t e r added t o t h e d e l t a e x p r e s s e d as p e r c e n t d e t r i t u s (^) , m i c r o a l g a e , and macroalgae (^ )^ • (average o f f o u r s t a t i o n s ) 63 a. M a r s h l a n d b. Sand/mud f l a t s 12. P a r t i c u l a t e o r g a n i c m a t t e r removed t h r o u g h Snag and P i l e c r e e k s as p e r c e n t d e t r i t u s (^) , m i c r o a l g a e , and macroalgae (composite d a t a from low and h i g h c r e e k l e v e l s ) 66 13. Cavex l y n g b y e i meadow i n e a r l y March, showing mat o f decayed v e g e t a t i o n , and i n l a t e J u l y a t t h e time o f maximum growth.... 99 14. Energy i n p u t ( g r o s s p r o d u c t i o n ) f o r each major p r o d u c e r , s e p a r a t e d i n t o d i s s o l v e d o r g a n i c (^) , p a r t i c u l a t e o r g a n i c (JJJj)* and r e s p i r a t i o n (fy^) . The numbers ilndeEgteach -2 p r o d u c e r r e f e r t o a v a i l a b l e PAR (kcal«m -1 5 y x 10"; o v e r t h e growth p e r i o d and p h o t o s y n t h e t i c e f f i c i e n c y {%), r e s p e c t i v e l y . ( M i n o r p r o d u c e r s , e.g. A s s o c i a t i o n s B, C not i n c l u d e d ) 103 x i i i 15. Energy Input (gross production) for each major producer, separated into dissolved organic (^) , pa r t i c u l a t e organic (JJJj) , and r e s p i r a t i o n . (Minor Associations B and C not included) 106 — 2 —1 16. Energy flow (kcal-m -md ) through major benthic a l g a l producers i n f a l l (September), winter((December), spring (March) and summer (June). Numbers above each bar ref e r to d i s t r i b u t i o n a l area i n square meters 109 17. Seasonal pattern of energy storage (net production) by Carex lyngbye-C and benthic algae, energy removal as POM and the rates of energy removal/energy storage 119 18. Proposed energy flux through(7ares l y n g b y e i (above and below ground) and benthic algae. Relative percentages derived from Table 22 represent flux i n a " c h a r a c t e r i s t i c " square meter of delta surface :,.125 x i v LIST OF APPENDICES Appendix Page I. Light attenuation i n the water column adjacent to the d e l t a , as % incident radi a t i o n 144 I I . S a l i n i t y , temperature and incident radi a t i o n (PAR) 145 I I I . Nutrient concentrations i n t i d a l creeks (see F i g . 3 for sampling locations) CAg-at-l" 1) 147 IV. Annual sedimentation rates and sediment organic content (.LOI) determined from cores taken i n 1974 from locations i indicated below. A. Sp a t i a l v a r i a t i o n i n mean sediment-ation rates 148 B. Year of deposition, depth and LOI.... 149 V. Seasonal changes i n species composition of microalgal associations. Numbers represent r e l a t i v e percent composition... 151 VI. D i s t r i b u t i o n (coverage area) and biomass data for macroalgae and microalgal associ-ations 154 VII. Total biomass for macroalgae and micro-a l g a l associations as kg C'distr i b u t i o n a r e a - 1 15 8 XV 14 V I I I . C p r o d u c t i o n and o r g a n i c e x u d a t i o n d a t a (g C.m" 2.day - 1) 160 I X . E s t i m a t e d monthly p e r c e n t e m e r s i o n (exposed) and immersion ( c o v e r e d ) time f o r t h e Squamish d e l t a as de t e r m i n e d from t i d e t a b l e s 166 X. Turnov e r t i m e s f o r major p r o d u c e r s based on average biomass and p r i m a r y p r o d u c t i o n v a l u e s 167 X I . Annual net p r i m a r y p r o d u c t i o n e s t i m a t e s f o r Carex l y n g b y e i based on growth i n c r e m e n t s 168 X I I . Net energy p r o d u c t i o n f o r major a l g a l p r o d u c e r s . P r o - r a t e d v a l u e s r e p r e s e n t p e r c e n t o f t o t a l f o r each month ( c a l c u l -a t i o n s based on d a t a from T a b l e 12) 169 X I I I . Net energy p r o d u c t i o n 6f major a l g a l p r o d u c e r s . P r o - r a t e d v a l u e s r e p r e s e n t p e r c e n t d i s t r i b u t i o n o v e r t h e growth p e r i o d ( S a l c u l a t i o n s based on d a t a from T a b l e 12) 170 XIV. P r i m a r y p r o d u c t i o n and p h o t o s y n t h e t i c e f f i c i e n c y d a t a f o r c o n s t r u c t i n g s e a s o n a l energy f l o w pathways 172 xvi ACKNOWLEDGEMENTS I wish to express my sincere thanks to Dr. J.R. Stein for her advied, guidance, patience and f i n a n c i a l support provided by funds from NRC grant A1053. Research f a c i l i t i e s , equipment and ship time were made available.by the P a c i f i c Environment I n s t i t u t e , Department of Fisheries and Environment, Fisheries and Marine Service. I am deeply indebted to Dr. CD. Levings and Dr. J.G. Stockner for t h e i r i n t e r e s t , en-couragment and advice throughout the course of t h i s study. The he l p f u l suggestions, c r i t i c i s m s and comments of Dr. R.E. Foreman and Dr. P.G. Harrl'son concerning preparation of t h i s thesis are g r a t e f u l l y acknowledged. F i e l d assistance was provided by Mr. W. Fung, Mr. A. Shearon and Mr. R. Prange, a l l of whom I thank for putting up with the often unpleasant and always muddy conditipns of the Squamish delt a . 1 INTRODUCTION E s t u a r i e s and t h e i r a s s o c i a t e d d e l t a s and marshes form a b i o l o g i c a l l y i m p o r t a n t t r a n s i t i o n zone between the marine and f r e s h w a t e r environments (Odum 1971, Remane and Sc h l & e p e r 1971). T h e i r v u l n e r a b i l i t y t o i n d u s t r i a l development ( d r e d g i n g , l a n d f i l l , d y k i n g and p o l l u t i o n ) has f r e q u e n t l y been d i s c u s s e d (Odum 1971, P e r k i n s 1974). A l s o , t h e v a l u e o f s h a l l o w - w a t e r and i n t e r t i d a l marshes o f e s t u a r i e s as f e e d i n g and n u r s e r y areas f o r c o m m e r c i a l l y i m p o r t a n t f i s h and s h e l l -f i s h (Anonymous 1972, P e r k i n s 1974) and as a so u r c e o f o r g a n i c m a t t e r ( d e t r i t u s ) f o r ecosystems o f a d j a c e n t c o a s t a l w a t e r s ( M e l c h i o r r i - S a n t o l i n i and Hopton 1972, H e i n l e and Flemer 1976) has been n o t e d . E s t u a r i e s are among t h e most h i g h l y p r o d u c t i v e o f n a t u r a l ecosystems. Most i n f o r m a t i o n r e l a t i n g t o t h e a u t o t r o p h i c components ( p r i m a r i l y b e n t h i c a l g a e ) o f e s t u a r i n e ecosystems has been g a t h e r e d from c o a s t a l p l a i n s a l t marshes on t h e e a s t c o a s t o f t h e U n i t e d S t a t e s (Pomeroy 1959, W i l l i a m s 1962, G a l l a g h e r and D a i b e r 1973, 1974, S u l l i v a n 1977), Canada ( H a t c h e r and Mann 1975), E n g l a n d ( C a r t e r 1932, 1933, Hopkins 1966) and South A f r i c a (Day 1950, Day et al 1952, 1953). F j o r d - t y p e e s t u a r i e s o f Norway and Denmark have a l s o p r o v i d e d c o n s i d e r a b l e i n f o r m a t i o n ( G r o n t v e d I960, N i e n h u i s 1971, Gargas 1972). A summary o f e x i s t i n g l i t e r a t u r e on t h e b e n t h i c a l g a l component o f e s t u a r i e s 2 i s g i v e n by Pomeroy (1974) and t h a t f o r v a s c u l a r p l a n t s by Keefe (1972) and T u r n e r (1976). P a s t r e s e a r c h i n e s t u a r i n e ecosystems has g e n e r a l l y been d i r e c t e d t o s t r u c t u r e ( s p e c i e s c o m p o s i t i o n and d i s t r i b u t i o n - a b u n d a n c e ) w i t h l i t t l e a t t e n t i o n p a i d t o f u n c t i o n (energy and m a t e r i a l f l o w t h r o u g h t h e s y s t e m ) . The work by T e a l (1962) on a s a l t marsh ecosystem i n G e o r g i a i s t h e b e s t documented study o f energy f l o w . A s i m i l a r approach I s needed f o r o t h e r t y p e s o f e s t u a r i e s t o g a i n a f u l l u n d e r s t a n d i n g o f t h e i r impor-t a n c e and o p e r a t i o n . The p r e s e n t study was f o r m u l a t e d t o p r o v i d e some i n d i c a t i o n o f the s t r u c t u r e and f u n c t i o n o f t h e l i t t l e s t u d i e d f j o r d - t y p e e s t u a r i e s common t o B r i t i s h Columbia. The Squamish R i v e r e s t u a r y was s e l e c t e d as " t y p i c a l " o f t h e s e i n view o f i t s p h y s i c a l and b i o l o g i c a l s i m i l -a r i t y ( L e v i n g s et al. 1976). P a r t i c u l a r emphasis i s p l a c e d on the a u t o t r o p h i c components o f t h e i n t e r t i d a l marshes. F i e l d and l a b o r a t o r y e x p e r i m e n t s were d e s i g n e d t o : a.) i d e n t i f y f a c t o r s l i m i t i n g o r c o n t r o l l i n g d i s t r i b u -t i o n and p r i m a r y p r o d u c t i o n o f b e n t h i c a l g a e ; b.) d e t e r -mine the amount o f energy f l o w i n g i n t o and t h r o u g h v a s c u l a r p l a n t s and b e n t h i c a l g a e and t h e r o l e o f each i n t h e ecosystem ( I . e . p r i m a r y pathways o f energy f l o w ) ; c.) d e l i n e a t e t h e magnitude o f s e a s o n a l and a n n u a l p a t h -ways o f energy f l o w ; and d.) d etermine t h e Importance 3 o f the t i d a l marsh as an energy source f o r e s t u a r i n e organisms as w e l l as those o f adjacent c o a s t a l waters. Data from these q u e s t i o n a r e a s , when combined, may have a p r e d i c t i v e value r e g a r d i n g the e f f e c t s o f environmental a l t e r a t i o n on energy flow and ecosystem f u n c t i o n . T h i s study r e p r e s e n t s the f i r s t attempt at g a i n -i n g an understanding o f ecosystem f u n c t i o n i n a f j o r d -type e s t u a r y , a very complex, .-dynamic environment. Understanding the primary pathways o f energy flow from v a s c u l a r p l a n t s and b e n t h i c algae i n such a system i s h i g h l y important, ISor I t i s the base upon which the remainder o f the ecosystem i s b u i l t . 4 STUDY AREA The Squamish River estuary (49°4l' N, 123°lo' W) i s located approximately 48 km north of Vancouver, B r i t i s h Columbia at the head of Howe Sound (Pig. 1). The area Is representative of a turbid outwash f j o r d (Burell and Matthews 1974) and i s bounded on both sides by steep mountains. The entire Squamish estuary has been affected by i n d u s t r i a l development and physical a l t e r a t i o n (Anonymous 1972). The most s i g n i f i c a n t has been the construction of a r i v e r t r a i n i n g dyke running the length of the estuary (Fig. 2), and the establishment of two rather d i s t i n c t habitats (Pomeroy and Stockner 1976). The region west of the dyke i s under strong freshwater influence as a r e s u l t of the r e d i r e c t i o n of v i r t u a l l y the entire flow of the Squamish River to t h i s area. In comparison, the region £ 0 the east of the dyke i s now a r e l a t i v e l y stable habitat displaying mar-ine conditions, r e s u l t i n g from blockage of the east arm of the Squamish River and formation of the Central Basin (Fig. 2). The Squamish estuary has been separated into West, Central and East deltas on the basis of major physio-graphic features (training dyke and Central Basin (Fig. 2). Of these, the seaward portion of the Central delta best f i t s the two main requirements for th i s study. F i r s t l y , since the delta i s located within an area 5 Figure 1. Southern coast of B r i t i s h Columbia showing the l o c a t i o n of Howe Sound w i t h the Squamish estuary at the head. JO-6 Figure 2. Squamish River estuary, B r i t i s h Columbia, showing physiographic d e t a i l s of the delta ( indicates extent of sand/mud f l a t s exposed at low t i d e ; dotted area of the Central d e l t a indicates study region; L indicates location of l i g h t meter). 7 removed from the unsettling and complicating effects of direct r i v e r flow, more accurate studies r e l a t i n g to annual primary production, nutrient c y c l i n g , removal and deposition of par t i c u l a t e organic matter and other parameters required for the formulation of energy budgets may be undertaken. Secondly, the area chosen drains through two major t i d a l creeks, thus f a c i l i t a t i n g the measurement of organic and nutrient removal. 5 2 The study area of ca. 1.27 x 10^ m i s character-ized by an i n t e r t i d a l zone of extensive, low elevation marshlands i n combination with sand/mud f l a t s . The area has been separated Into three recognizable zones by Levlngs (1974). The lower i n t e r t i d a l zone (0.0-1.5 m above chart datus (O.D.)) has sand/mud sediments free of vascular plants. Marshlands supporting vascular plant communities common to developing a l l u v i a l lands are i n d i c a t i v e of the mi d - i n t e r t i d a l zone (1.6-3.0 m O.D.). The t r a n s i t i o n between th i s zone and the lower i n t e r t i d a l i s generally delineated by a natural embank-ment ranging In height from 0.3-1.8 m. A dense over-hanging mat of Carex lyngbyei Hornem. rhizomes i s common, extending out into the low i n t e r t i d a l sand f l a t s for approximately 0.2 m (Levlngs 1974). The mi d - i n t e r t i d a l marshland i s dominated by extensive sedge meadows of C. lyngbyei and Eleoolnavie p a l u a t r i s (L.) R. and S. dissected by t i d a l creeks (Lim and Levlngs 1973). Die-o f f of sedge occurs gradually beginning In late August and by December aimat of dead vegetation Is present. 8 A gradation exists from sedge to grasses on the higher levels of the upper I n t e r t i d a l lands (3.1-4.5 m O.D.). Deciduous shrubs and mixed coniferous trees such as Douglas f i r (Pseudotsuga m e n z i e s i i (Mirbel)France) and western hemlock (Tsuga h e t e r o p h y l l a (Raf.) Sarg.) occupy the infrequently flooded landward portion of the d e l t a above the i n t e r t i d a l . O r l o c i (1961) and Krajina (1970) indicate the Squamish delta as being within the coastal western hemlock zone of the P a c i f i c coastal meso-thermal forest region. Climate i n the study area i s classed as moderate maritime with a mean annual p r e c i p i t a t i o n of 203 cm (Hoos and Void 1975). Average monthly a i r temperatures range from near 0 C i n January to 17 C In July. Steep mountains and a frequent i n d u s t r i a l haze layer e f f e c t i v e -l y reduce duration and i n t e n s i t y of sunlight. Wind patterns are t y p i c a l of those p r e v a i l i n g i n many B r i t i s h Columbia fjords (Hoos and Void 1975). Strong northerly outflows, common during December and January, frequently •reach 56-64 km'h-"1" and may p e r s i s t for 3-5 days. South-erly Inflow winds (October to March) are less persistent but more frequent than northerly winds. A diurnal sea breeze c i r c u l a t i o n (25-37 km'h"1), r e s u l t i n g from strong thermal heating i n the i n t e r i o r , i s evident during the summer. Strong amplification of winds occurs i n the immediate v i c i n i t y of the Squamish estuary on sunny days, being attributed to valley winds or overheated a i r i n the estuary r i s i n g up the steep mountain sides 9 (Anonymous 1972). D i s c u s s i o n o f wind and o t h e r c l i m a t i c f a c t o r s a r e g i v e n by S t a t h e r s (1958) and Hops and V o i d (1975). 2 The Squamish R i v e r system d r a i n s 2500 km o f t h e w e s t e r l y s l o p e s o f t h e Coast Mountains i n s o u t h e r n B r i t i s h C olumbia. Annual d i s c h a r g e p a t t e r n s a r e c h a r -a c t e r i s t i c o f g l a c i e r f e d systems w i t h a mean an n u a l f l o w r a t e o f aa. 292 n r * s , D u r i n g t h e h i g h r u n o f f p e r i o d (May t h r o u g h A u g u s t ) , peak f l o w s o f aa. 658 m ' S are common (J u n e , J u l y ) (Bell"1975). Minimum f l o w r a t e s (oa. 71 m -s ) g e n e r a l l y o c c u r i n March. A second pronounced r u n o f f can o c c u r i n t h e f a l l as a r e s u l t o f heavy r a i n s o r premature snow m e l t . The Squamish R i v e r i s h e a v i l y l a d e n w i t h g l a c i a l sediments a t t h e time o f maximum r u n o f f ( J u n e - J u l y ) . R i v e r w a t e r i s c a r r i e d around t h e dyke and sediments become d e p o s i t e d a t t h e d e l t a f r o n t . B e l l (1975) i n d i c a t e s an average r a t e o f d e l t a f r o n t advancement a p p r o a c h i n g 6.0 m-yr" 1. Sediments o f t h e d e l t a a r e c l a s s e d as P l u v i a l ( a l l u v i a l ) - G l a c i a l M a r i n e w i t h a s l o p e o f l e s s t h a n 5% (Anonymous 1972). C o a r s e r s e d i -ments become d e p o s i t e d on t h e upper p o r t i o n s o f t h e d e l t a . F i n e r c o l l o i d a l p a r t i c l e s ( g l a c i a l f l o u r ) f l o c c u l a t e w i t h t h e m i x i n g o f f r e s h and marine w a t e r s and s e t t l e towards t h e seaward p o r t i o n o f t h e d e l t a . Data on m i n e r o l o g y , sediment d i s t r i b u t i o n and g r a i n s i z e a r e p r o v i d e d by Matthews a l . (1966) and B e l l (1975). 10 Tides a f f e c t i n g the delta are of the mixed type t y p i c a l of the P a c i f i c Coast with two high and two low periods i n a t i d a l day. T i d a l amplitude varies from 0 to 4.8 m O.D. with mean t i d a l range being 3.2m O.D. (Anonymous 1972). During periods of strong winds and high runoff, these l i m i t s can be greatly exceeded. Thus, the extent and duration of exposure and coverage of the i n t e r t i d a l region can be extremely variable. 11 MATERIALS AND METHODS F i e l d studies were conducted from June 1974 through August 1975. Sampling was done weekly or biweekly from June to September 1974 and 1975. For the period September 1974 through A p r i l 1975, sampling was done monthly. Station locations for phy s i c a l , chemical and b i o l o g i c a l factors appear i n Figure 3-I. Physical-Chemical Factors  A. S a l i n i t y , temperature, p r e c i p i t a t i o n , l i g h t . F i e l d determinations of s a l i n i t y and temperature at high tide were made at the surface and at 1 and 2m. A YSI Model 33 SCT meter was used June-August" 1974, followed by a Beckman Model RS5-3 SCT meter for subsequent work. S a l i n i t y of samples co l l e c t e d i n the f i e l d was determined using a Bissett-Berman Salinometer (Model 6230) on return to the laboratory. Temperature determinations i n t i d a l pools were made with standard mercury thermometers. Ai r temperature and p r e c i p i t a t i o n data were obtained from the Squamish-St. Davids monitoring st a t i o n of the Atmospheric Environment Service (AES) located just north of Squamish. —2 —1 Daily incident solar r a d i a t i o n (g cal*cm -day ) was recorded on a Belfort Pyranometer situated, to prevent vandalism, at Squamish Terminals on the East delta (Fig. 2). Days were i d e n t i f i e d as sunny or 12 Figure 3 . Detailed map of Central delta showing sampling stations, indicates extent of sand/mud f l a t s exposed at low t i d e . • seasonal nutrients • nutrient loss from t i d a l creeks J2f sedimentation and sediment organics V addition of p a r t i c u l a t e organic matter • removal of p a r t i c u l a t e organic matter -del t a surface <8> removal of p a r t i c u l a t e organic matter - t i d a l creeks t i d a l creek flow rates l i g h t attenuation with depth salinity-temperature stations ^ *- — ' C E N T R A L BASI N 13 overcast based on data from the AES station and from pyranometer tracings. On overcast days, solar energy was assumed to be e n t i r e l y photosynthetically available r a d i a t i o n (PAR = 400-700 nm) (Szeicz 1966). However, due to the reduction i n atmospheric f i l t e r i n g on sunny days, the value obtained from the pyranometer was multip l i e d by 0.47 to determine PAR (Vollenweider 1974). Monthly PAR estimates were derived using weekly pyrano-meter charts. A Montedoro-Whitney underwater photometer (Model LMT-8a) was used to measure percent l i g h t attenuation with depth i n the water column (Fig. 3). Percent l i g h t reduction at the sediment surface by marsh vegetation was determined using a simple hand-held Gossen l i g h t meter. B. A l k a l i n i t y , pH, nutrients. Samples of water to be used f o r incubation i n primary production experiments col l e c t e d at the edge of the de l t a were analysed for pH and a l k a l i n i t y using an Orion D i g i t a l pH meter, Model 801. Carbonate a l k a l -i n i t y for use i n productivity equations was determined according to Strickland and Parsons (1972). Analyses were done within 6 h of c o l l e c t i o n . Sample c o l l e c t i o n and subsequent analyses for ortho-phosphate, ammonia, n i t r a t e and n i t r i t e were done using methods of Strickland and Parsons (1972). Samples were transported to the laboratory i n ice chests and 14 immediately frozen u n t i l analysis, conducted within 4 wk. Surface water samples were taken on the east side of the dyke at monthly Intervals at high slack water for seasonal nutrient analyses (Pig. 3). Nutrient losses from P i l e and Snag creeks were monitored at 3-4 month i n t e r v a l s . Samples were taken when the tide f e l l below the marsh surface, again at about mid-ebb t i d e , and f i n a l l y near low slack water at a point 10 m from the creek mouths (Pig. 3). Background nutrient le v e l s present p r i o r to ebb tide were deter-mined from samples taken over the delta on the preceeding high t i d e . Values were corrected for background concen-trations and combined with information on flow rates of the creeks to provide estimates of nutrients "leached" from the sediment and carried o f f the d e l t a over an ebb t i d e . C. Sediment and organic deposition patterns. Pour sediment cores (5 cm diam.) were taken i n June 1974 from the seven major sediment-habitat types on the delta (Pig. 3, see Appendix V for area descrip-t i o n s ) . The cores were extruded, wrapped i n aluminum f o i l and returned to the laboratory for analysis. Cores were i n i t i a l l y sectioned l o n g i t u d i n a l l y to expose surfaces undisturbed by the coring process. Annual layers, i d e n t i f i e d by differences i n sediment p a r t i c l e size and presence of vascular plant remains, were 15 measured and separated. Each layer was taken, mixed thoroughly and the wet weight determined. Pour weighed subsamples were then taken from which moisture and organic content were determined by drying to constant weight at 100 C, weighing and ashing i n a muffle furnace 4 h at 500 C. M u l t i p l i c a t i o n of the ash-free dry weight ( i . e . organic content) by 0.5 gave estimates of g O g dry wt sediment - 1, as organic matter was assumed to be 50 % carbon based on estimates given by Westlake (1963). Estimates of sedimentation during freshet were made by securing centimeter rulers v e r t i c a l l y to s o l i d substrates and recording depth changes over time. D. T i d a l creek flow rates. Flow rates were determined for P i l e and Snag creeks at 20 min i n t e r v a l s over an ebb tid e i n A p r i l and June 1975. A pole, marked o f f i n 5 cm i n t e r v a l s , was secured i n place v e r t i c a l l y i n the deepest part of the creek bed. On the following day, measurements of flow rate (F) were begun when the l e v e l of the creek f e l l below the marsh surface. The time (T) i n seconds for a wooden block 4 x 6 cm to t r a v e l a distance (L) of 1 m and the width (W) and depth (D) i n m of water i n the creek were noted. The sections of the creeks chosen for the deter-mination of flow rates (Pig. 3) approximated rectangles; thus an equation based on the volume of a rectangle was derived: 16 , , ( L x W x D ) * ( 1 - s - 1 ) = x 10^ (1) T 3 -3 _1 -1 where: 10 = f a c t o r f o r e x p r e s s i n g m J»s as 1-s I I . B i o l o g i c a l F a c t o r s A. D i s t r i b u t i o n ( c o v e r a g e ) a r e a ) , biomass. Four q u a d r a t samples (0.06 m^) o f a m a c r o a l g a l s p e c i e s o r a m i c r o a l g a l a s s o c i a t i o n were randomly s e l e c t e d from w i t h i n t h e coverage a r e a . Sediments were s c r a p e d t o a depth o f 0.2 cm f o r d i a t o m a s s o c i a t i o n s . M a c r o a l g a l samples were c l e a n e d o f v a s c u l a r p l a n t m a t e r i a l and sediment p r i o r t o a n a l y s i s . Samples were oven d r i e d a t 100 C t o c o n s t a n t w e i g h t , ground and r e d r i e d 2 h p r i o r t o dry weight d e t e r m i n a t i o n s . Three e q u a l l y w e i g h t e d sub-samples were t h e n removed and t r e a t e d i n t h e same manner as o r g a n i c m a t t e r i n t h e sediment c o r e s ( p a r t i C , p r e c e e d l n g ) . S t a n d i n g crop _2 biomass was e x p r e s s e d as g Om D i s t r i b u t i o n o r coverage a r e a f o r each m a c r o a l g a l s p e c i e s and m i c r o a l g a l a s s o c i a t i o n was e s t i m a t e d u s i n g a c o m b i n a t i o n o f ground s u r v e y and a e r i a l p h o t o g r a p h s . P l o t s were made from t h e s e d a t a showing s e a s o n a l d i s t r i -b u t i o n o f a l g a e f o r f a l l , w i n t e r , s p r i n g , and summer. B. P r i m a r y p r o d u c t i o n . Two methods were employed f o r t h e d e t e r m i n a t i o n o f b e n t h i c a l g a l p r i m a r y p r o d u c t i o n . The f i r s t was 14 t h e r a d i o a c t i v e c a r b o n ( C) t e c h n i q u e based on uptake 17 and f i x a t i o n of CC^. The second was the dissolved ..oxygen method based on an equivalence of oxygen evolved and organic material produced. The basic techniques are described i n d e t a i l by Strickland and Parsons (1972) and Vollenweider (1974). 14 The C technique was used to obtain seasonal production estimates for reasons of greater accuracy i n waters having high dissolved organic content and high nutrient concentrations such as were present at Squamish (Strickland and Parsons 1972). Gross production 14 values, unattainable by the C method, are desirable fo r the construction of energy budgets. Dissolved oxygen production data provided an experimental basis for extra-14 polating C values which were assumed to approximate net production (Parsons and Takahashi 1973). Carbon-14 method. Water samples for incubation were collected at the edge of the delta (Fig. 3) and o f i l t e r e d through a 10/<>m mesh Nitex screen. Produc-t i v i t y bottles (two 135 ml l i g h t and one 135 ml dark) 2 were f i l l e d and a sample of algae, aa. 0.5 cm , cleaned of extraneous organic matter and sediment, was added to each b o t t l e . In mud and sand microalgal associations, 2 the 0.5 cm sediment sample was scraped to a depth of 0.2 cm and added to the b o t t l e s . Production bottles were inoculated with 1 ml of radio-isotope stock 14 solution 100/*-CI C-NaHCO^ i n 10 ml s t e r i l e water (pH 9.5) (New England Nuclear) d i l u t e d with 75 ml d i s t i l l e d deionized water, using ah automatic pipette. 18 C o n t r o l s e t s w i t h o u t a l g a l m a t e r i a l were r u n t o account f o r m e t a b o l i c a c t i v i t y o f m i c r o - o r g a n i s m s p a s s i n g t h r o u g h t h e s c r e e n . Each day a p r o d u c t i o n experiment was done, t h e number o f d i s i n t e g r a t i o n s p e r minute (dpm) p e r ml were d e t e r m i n e d by p l a c i n g 1 ml s t o c k s o l u t i o n i n t o each o f t h r e e v i a l s c o n t a i n i n g 15 ml o f A q u a s o l (New England N u c l e a r , L i q u i d S c i n t i l l a t i o n C o c k t a i l ) . Sample i n c u b a t i o n was done a t two depths t h r o u g h -out t h e s t u d y . D u r i n g t h e l a t e s p r i n g and summer, when daytime low t i d e s predominated l e a v i n g t h e a l g a e e i t h e r t o t a l l y exposed o r i n s h a l l o w p o o l s , b o t t l e s were i n c u b a t e d i n t i d a l p o o l s aa. 15 cm deep. However, d u r i n g t h e f a l l and w i n t e r , when h i g h t i d e s o c c u r r e d d u r i n g the day, b o t t l e s were suspended as d e s c r i b e d by Pomeroy (1974) a t aa. 15 cm below t h e s u r f a c e i n t h e a r e a o f t h e d e l t a . The v a l u e s o b t a i n e d from t h e s e I n c u b a t i o n s a r e r e f e r r e d t o as s u r f a c e p r o d u c t i o n . I n a d d i t i o n , b o t t l e s were suspended a t 1 m. The p r o d u c t i o n v a l u e s o b t a i n e d , when combined w i t h i n f o r m a t i o n on t i d e c o v e r , p r o v i d e d more a c c u r a t e d a i l y p r o d u c t i o n e s t i m a t e s . A l l i n c u b a t i o n s , o f c a . 4 h d u r a t i o n , were done i n s i t u y g e n e r a l l y between 1000 and 1400 h. F o l l o w i n g i n c u b a t i o n , 2 drops c o n c e n t r a t e d f o r m a l i n were added t o each b o t t l e b e f o r e r e t u r n t o t h e l a b o r a -t o r y , w i t h a n a l y s e s done w i t h i n 3 h. The c o n t r o l s e t s p were f i l t e r e d onto S a r t o r i o u s 0.45/*-m pore d i a m e t e r c e l l u l o s e a c e t a t e f i l t e r s w h i c h were t h e n exposed t o fumes o f cone. HC1 f o r 10 min t o removed any a c t i v e C00 19 p r e c i p i t a t e d as c a r b o n a t e . F i l t e r s were t h e n p l a c e d i n s c i n t i l l a t i o n v i a l s w i t h 15 ml A q u a s o l . B o t t l e s c o n t a i n -i n g m i c r o a l g a l a s s o c i a t i o n s from sand/mud s u b s t r a t e s were shaken and a l l o w e d t o s e t t l e 10 sec when much o f t h e h e a v i e r sediment p a r t i c l e s s e t t l e d . The s u p e r n a t a n t was f i l t e r e d onto S a r t o r i u s f i l t e r s and t r e a t e d as d e s c r i b e d . M a c r o a l g a l samples were removed from t h e b o t t l e s by f i l t e r i n g onto pre-weighed S a r t o r i u s f i l t e r s . I n t a c t a l g a e ( t h a l l i , l a r g e f i l a m e n t s ) were removed from t h e f i l t e r s , b l o t t e d dry and exposed t o cone. HCl fumes, b l o t t e d dry a g a i n and weighed (wet w t . ) . S m a l l f i l a -mentous a l g a e and sand/mud m i c r o a l g a l a s s o c i a t i o n s were t r e a t e d as f o r macroalgae except t h e m a t e r i a l was removed by s c r a p i n g . A l l a l g a l m a t e r i a l t h u s t r e a t e d was p l a c e d i n g l a s s s c i n t i l l a t i o n v i a l s w i t h 1 ml P r o t o s o l (New E n g l a n d N u c l e a r ) and d i g e s t e d f o r 24 h a t 50 C. Subse-q u e n t l y , 15 ml o f s p e c i a l l y p r e p a r e d s c i n t i l l a t i o n f l u o r [5.5 g PPO p l u s 50 mg POPOP (New England N u c l e a r ) t o 1 1 w i t h 1:2 ( v / v ) 2 - e t h o x y e t h a n o l , t o l u e n e ] (UNESCO 1973) was added t o each v i a l . D i s s o l v e d o r g a n i c m a t e r i a l (DOM) r e l e a s e d from a l g a e d u r i n g ^ ^ ^ C i n c u b a t i o n p e r i o d s may r e p r e s e n t a 14 s i g n i f i c a n t p o r t i o n o f t h e t o t a l d a i l y C uptake and p r o d u c t i o n ( S i e b u r t h 1969). To account f o r t h i s l o s s and p o s s i b l e u n d e r e s t i m a t e s o f p r o d u c t i o n , f i l t r a t e s c o l l e c t e d from l i fC p r o d u c t i o n l i g h t b o t t l e s (Watt 1965) were t r e a t e d t o remove a c t i v e i n o r g a n i c carbon d i o x i d e and r e t a i n v o l a t i l e o r g a n i c m a t e r i a l exuded d u r i n g 20 production (carbohydrates, nitrogenous, polyphenolic materials). Modifying the method of Sieburth ( 1 9 6 9 ) , four r e p l i c a t e s of 2 ml f i l t r a t e from each l i g h t b o t t l e were placed i n glass s c i n t i l l a t i o n v i a l s , a c i d i f i e d with 0.2 ml 3 % phosphoric acid and purged 15 min with pure nitrogen, followed by the addition of 15 ml Aquasol. Tests were also run on f i l t e r e d water without added a l g a l material to check for background l e v e l s of d i s -solved organic material. The a c t i v i t i e s of stock s o l u t i o n , control sets, a l g a l samples and l i g h t b o t t l e f i l t r a t e s were determined on a Packard Tri-Carb Liquid S c i n t i l l a t i o n Spectro-photometer (Model 3375). 14 The equation used to convert dpm to mg C-DOM released was L, _ x 67.5 d P m A (2) -x i, C0 2 x 1.05 _2 mg algae (wet wt.) mg Om~ "day" = x P x Dw Lt x a where: ~ d P m l n 2 ml sub-sample from l i g h t b o t t l e ; 67.5 = factor to express dpm/135 ml b o t t l e ; 4 C 0 2 = t o t a l C0 2 i n b o t t l e as mg C (Strickland and Parsons 1972); 1.05 = isotope correction factor; Lt = PAR during Incubation/daily PAR; a = absolute a c t i v i t y (dpm) of added isotope stock; P = conversion factor f o r wet to dry wt. of algae; Dw = dry wt. of algae (mg«m ). 21 The equation used to convert dpm to mg par t i c u l a t e _2 C fixed*m was: R x3 .C0 2 x 1.05 mg Cm" 2'day - 1 = x P x Dw (3) Lt x a where: R = dpm/unit wet wt l i g h t bottle - dpm/unit wet wt dark b o t t l e . Estimates of t o t a l net primary production were then made by combining the values from Equation 2 on organic exudates (DOM) and Equation 3 on pa r t i c u l a t e organics (POM) (Parsons and Takahashi 1973, Sellner et a l . 1976). Dissolved oxygen method. At int e r v a l s throughout the study, primary production was determined with a modified l i g h t and dark bo t t l e dissolved oxygen (DO) technique (Strickland and Parsons 1972). Alg a l samples 2 of ca. 4 cm were added to 300 ml DO bottles (2 l i g h t , 1 dark) containing water pretreated as described for the 14 C method with control sets minus algae and incubated as described. Production values are expressed as mg O ^ l - 1 _2 (Strickland and Parsons 1972) and converted to mg Cm d a y - 1 using the equation: mg 0 9 * 1 - 1 x 0.3 x C — 2 —1 mg Cm -day = x W (4) Lt where: 0.3 = correction factor for 0 2 content i n 300 ml b o t t l e ; C = conversion factor for mg 0 2 to mg C (macroalgae PQ = 1.20, C = 0.278; microalgae 22 with higher fat content PQ = 1.25, C • 0-.300 (Westlake 1963)); Lt = PAR during incubation/daily -2 PAR;{ W = dry wt of algae'm / dry wt of algae incubated. C. Removal, deposition of pa r t i c u l a t e organic matter (POM). For removal of POM (intact macroalgae, microalgae and d e t r i t a l material—dead organic matter of plant or animal o r i g i n with associated micro-organisms (Mann 1972)) during floodtide and Its addition to the water column, two sampling transects were selected at the delta front, one on the western sector and one on the eastern (Fig. 3). Seven stations were sampled along each, covering the major a l g a l growth forms and habitats. Samplings were also made i n the upper I n t e r t i d a l . p Wooden cages (50 cm x 40 cm high) covered on four 2 sides with 352>\m Nitex screening were used (Fig. 4). The mesh size allowed r e l a t i v e l y free water movement into the cages for "normal" removal of POM but r e s t r i c t e d entry of larger plant material. The cages were i n i t i a l l y placed on the sand/mud f l a t s at the seaward edge of the delta and secured with s t e e l pegs. Prior to the incoming tide reaching the l e v e l where the cages were located, two 1 1 water samples were taken outside the cage for analysis of "background" POM (amount before the ti d e reaches a s p e c i f i c l e v e l on the delta) and microscope examination. Subsequently, when the incoming tide reached a predetermined depth and thus a known water 23 Figure 4. Diagram of cage used for studies of pa r t i c u l a t e organic removal i n place on the de l t a . 23a i 2k volume i n the cages, 1 1 water samples were taken from inside f o r the above noted analyses. The cages were rinsed and then moved back to an area of the delta not yet reached by the incoming tid e where the sampling procedure was repeated. Samples for microscope examination were preserved i n Lugol's solution and examined using the Utermohl (1958) sedimentation technique. I d e n t i f i c a t i o n of algae as to planktonic and benthic, the r e l a t i v e domin-ance and estimates of the proportion of macroalgae, microalgae and detritus were made. One l i t e r water samples were f i l t e r e d onto pre-ashed and weighed Whatman GPC glass f i b e r f i l t e r s . Analysis for organic content was as previously described. The organic content was estimated by: C. - C, x V -2 -1 1 b mg C removed«m • flood t i d e = (5) a where: C i = mg C ' l " 1 inside cage; C b = mg C - l - 1 background l e v e l outside cage; V = water volume _ p inside cage (1); a = area of enclosure (m ). To study removal of POM v i a t i d a l creeks on an ebb t i d e , measurements were done In the major creeks when the water l e v e l f e l l to the surface of the marsh. Stations were established aa. 10 m back from the mouths of Snag and P i l e creeks (Pig. 3). Two 1 1 samples were taken at high (15 cm below water surface) and low (near creek bottom) water l e v e l , with determination of organic 25 content and microscope examination carried out as described. Estimates of the t o t a l amount of POM leaving the marsh through t i d a l creeks on an ebb tide were possible by combining data on g C«l~^" with that on flow rates. The addition of POM was determined monthly by measurements of amounts deposited on the mud/sand f l a t s and on the marshland over a t i d a l cycle. Sampling s i t e s were located i n the low, mid, and upper i n t e r t i d a l zones (Pig. 3 ) . Large size p l a s t i c p e t r i dishes of known area were secured with t h e i r openings aa. 3 cm above the surface of the sediment at one low tide and retrieved on the following low t i d e . The sample was s p l i t , with h a l f being used for microscope examination and h a l f for determination of organic content as described. - 2 -1 Results are expressed as mg C deposited*m ' t i d a l cycle D. Calo r i c equivalents. Caloric equivalents were determined for the major benthic a l g a l producers, vascular plants, d e t r i t u s , sediment organics and material removed from and deposited on the del t a . Sediments with microalgal associations and d e t r i t a l deposits were scraped to a depth of 0 .5 cm. Material collected from removal and deposit s i t e s ( Fig. 3) was returned to the laboratory i n i c e chests within 3 h where i t was immediately centrifuged to remove excess water. The samples were placed i n p l a s t i c bags and frozen u n t i l analysis could be performed (up to 10 mo 26 a f t e r c o l l e c t i o n ) . At the time of analysis, macroalgae and vascular plant material were l i g h t l y washed i n d i s t i l l e d water to remove sediment p a r t i c l e s . A l l samples were dried to constant weight at 80 C rather than 100 C to reduce the p r o b a b i l i t y of denaturing proteins or v o l a t i l i z i n g energy r i c h materials (Paine 1971). Samples were ground to a fin e powder. For sediment organics and microalgal associations with low c a l o r i c content/g material, a known amount of benzoic acid standard was added to the sample to bring the value to a readable l e v e l . Replicates were taken for each sample and burned In a P h i l l i p s o n Microbomb Calorimeter to determine cal*g dry wt - 1. Applying organic content to c a l o r i c _ i value, estimates were made of g cal'g organic material Equivalents were not determined for dissolved organic matter due to technical l i m i t a t i o n s . Values derived for the corresponding algae were used and are considered to be minima since the exudates are known to have higher c a l o r i c values than are inta c t c e l l s with c e l l u l o s e or s i l i c a walls (Paine 1971). E. A l g a l , plant and detritus u t i l i z a t i o n by amphipods. Abundant gammarid amphipods (Anisogammarue aonfer-vioolus (Stimpson)), an important food source for salmonids (Anonymous 1972), were associated with vascular plants, benthic algae and detritus i n the f i e l d . Studies were undertaken to determine the importance of these 27 to both adult (sexually mature) and juvenile i n terms of protection and a source of food. F i e l d studies. Observations were made on the relati o n s h i p of amphipods and cover type at low tide on each sampling date. Each macroalga and microalgal association was examined as well as d e t r i t a l material. A detailed examination of a section of the marshland was made (30 x 30 m g r i d i n the mid-Intertldal zone) noting associations at 1 m i n t e r v a l s . Observations were made as to whether or not amphipods were a c t i v e l y feeding (mouth parts being manipulated) on the plant material with which they were associated. Collections were made and amphipods placed immediately i n 10 % formalin. Subsequently, the gut was removed and opened for microscope examination to r e l a t e gut appearance to food consumed. Laboratory studies. Amphipods collected i n May and June 1975 for cover preference studies were fed on a mixture of decayed vascular plants, macroalgae and detritus c o l l e c t e d from the study area while being acclimated for 1 wk at 15 °/oo S. Subsequently, the amphipods were placed i n a tray containing separate clumps of each material i n ca. 2 cm water at normal room l i g h t . The number of amphipods associated with each clump was noted after 5 min. The short time i n t e r -v a l was selected to avoid the onset of feeding a c t i v i t y following a fright/cover response. 28 Experiments were conducted i n the laboratory to indicate food preference by starving f i e l d c ollected amphipods acclimated to 15 °/oo S. Trays were set up as described for cover studies, but were covered with black p l a s t i c sheeting to insure a "safe" feeding s i t u a t i o n . The number of amphipods a c t i v e l y feeding on each food source was noted aft e r 10 min. Cover and feeding experiments were repeated a number of times, varying the arrangement of materials i n the trays and the point at which the amphipods were introduced. Fatty acid spectra comparison. Past studies show that algae display c h a r a c t e r i s t i c f a t t y acid spectra i n the C ^ - C 2 2 range (Mclntyre et aV. 1969). Thus, experiments were designed to Identify gut contents and thus food source based on f a t t y acid spectra. Determin-ations were made of the various food sources as well as starved amphipods, amphipods fed on a single food source and amphipods coll e c t e d from the f i e l d . The extraction method used was a modification of those suggested by Mclntyre et a l . (1969), J e f f r i e s (1972) and Schultz and Quinn(:(J973). Ten g tissue ( a i r dry wt) was ground and placed i n a f l a s k with 100 ml of chloroform : methanol ( 2 : 1 v/v), a c i d i f i e d with 2 ml cone. HC1. Extraction proceeded for 24 h at 15 C, aft e r which the contents of the f l a s k were gravity f i l t e r e d through a Whatman # 1 f i l t e r paper previously leached with the chloroform : methanol acid 29 s o l u t i o n . The f i l t r a t e was c o n c e n t r a t e d i n a r o t a r y e v a p o r a t o r and t h e r e s i d u e d i s s o l v e d i n 10 ml p e t r o l e u m e t h e r and t r a n s f e r r e d t o a v i a l . M e t h y l a t i o n f o l l o w e d w i t h 1 ml diazomethane f o r 30 min. The e x t r a c t was t h e n d r i e d under N 2 gas i n a water b a t h (30 C ) . The sample was s o l u b i l i z e d w i t h 2 ml p e t r o l e u m e t h e r and a n a l y z e d i m m e d i a t e l y f o r t o t a l f a t t y a c i d c o n t e n t on a H e w l e t t P a c k a r d Gas Chromatograph (Model 5711 A-F.I.D.). The i n s t r u m e n t had flame i o n i z a t i o n d e t e c t o r s and was f i t t e d w i t h a s t a i n l e s s s t e e l Support Coated Open T u b u l a r column (49 m x 2 . 5 mm i n s i d e d i a m e t e r ) * p a c k e d w i t h d i e t h y l e n e g l y c o l s u c c i n a t e . D e t e c t o r and i n j e c t i o n t e m p e r a t u r e s were h e l d a t 200 C and column t e m p e r a t u r e a t 180 C I s o t h e r m a l . A 5/*-l sample was I n j e c t e d and an i n t e g r a t o r p r o v i d e d r e t e n t i o n t i m e s and r e l a t i v e abundance o f f a t t y a c i d s . I I I . A n a l y s i s o f f a c t o r s i n f l u e n c i n g  p r i m a r y p r o d u c t i o n A s t e p w i s e m u l t i p l e r e g r e s s i o n a n a l y s i s ('TRIP) was r u n on t h e UBC 370 computer t o t e s t t h e e f f e c t o f c e r t a i n e n v i r o n m e n t a l f a c t o r s — s a l i n i t y , l i g h t i n t e n s i t y , t e m p e r a t u r e , n i t r a t e , phosphate and ammonia—on net p r o d u c t i o n . S i n c e i t cannot be assumed t h a t any o f t h e s e f a c t o r s o p e r a t e i n d e p e n d e n t l y t o c o n t r o l p r o d u c t i o n ( Z a n e v e l d 1 9 6 9 ) , TRIP was chosen as a p p r o p r i a t e . 30 RESULTS I. Physical-Chemical Factors  A. S a l i n i t y , temperature, l i g h t . Daily means and monthly estimates of photosynthet-i c a l l y available ra d i a t i o n (400-700 nm) reaching the study area appear i n Table 1. Maximum values occurred i n July 1975, with the minimum i n January 1975. Light attenuation i n the water column adjacent to the delta was greatest during the maximum r i v e r flow period (June, July) (Fig. 5). Values immediately below the surface averaged aa. 50% of incident r a d i a t i o n whereas ill u m i n a t i o n at 2 m was as low as 2%. Minimum l i g h t attenuation occurred during the winter with 90% of incident rad i a t i o n recorded just below the surface. Illumination at 1 m averaged aa. 30% of incident r a d i a l t i o n and aa. 15% at 2 m (Fig. 5). Reductions i n the amount of incident r a d i a t i o n reaching the sediment surface on the marshland were evident with increased height of vascular plants (Table 2). Stands of Carex lyngbyei had a much greater shading ef f e c t at the sediment surface than did Eleooharis paluetvis. For the former, percent t o t a l incident radi a t i o n reaching the sediment was lowest at times of peak growth (aa. 6-14JS i n July) and upon formation of the dead vegetation mat i n November (aa. 2%). In comparison, the growth form of E. paZu8tris permitted much more l i g h t penetration, with a minimum of 37% 31 Table 1. Photosynthetically available r a d i a t i o n (400-700 nm) reaching the study area. Month Daily mean Monthly estimate —2 2 ^ (g cal'cm ) (kcal*cm xlO-5) June 255.0 ' 7.65 July 250.0 7.75 August 149.0 4.63 September 154.0 4.62 October 101.0 3 . 0 3 November 30.8 0.92 December 28.9 0.90 1975 January 20.0 0.63 February 29.8 0.83 March 26.0 0.81 A p r i l 94.2 2.83 May 210.6 6.53 June 264.6 7.94 July 266.4 8 . 2 6 August 134.2 4.16 32 Figure 5. Light attenuation with depth i n water column adjacent to the delta (data appear i n Appendix 1). 33a 33 Table 2 . Shading of the delta surface by attached vascular plants. Light attenuation as percent incident r a d i a t i o n Date Carex lyngbyei Eleocharis •palustvie height % Incident height % Incident (cm) r a d i a t i o n (cm) r a d i a t i o n 1974 14 60 19 July 50 15 60 14 30 48 110 6 - -27 August 40 26 15 58 60 12 40 44 80 10 - -13 September 20 24 15 60 40 10 40 50 50 6 — — 17 October 20 20 15 49 30 12 20 37 40 10 — — November - Prostrate mat of dead vegetation (ca. 15 cm high) with 2% of surface r a d i a t i o n noted. 1975 80 19 March 5 46 5 16 A p r i l 5 40 5 80 10 30 10 65 15 25 — — 14 May . 10 35 10 70 15 25 15 60 20 15 — — 20 June 20 20 15 60 40 15 20 48 60 12 - -18 July 40 20 20 55 65 14 30 44 100 8 — — 10 August 40 25 20 55 50 20 35 42 85 12 a-* 34 incident r a d i a t i o n recorded i n October (Table 2 ) . A i r temperatures during the day were highest i n August and lowest In January and February (Fig. 6 a ) . Daytime water temperatures just below the surface averaged 1 0 C during the high runoff period (May-August), with winter values near 5 C (Fig. 6 b ) . Temp-eratures at 1 m were 1 C higher than surface f o r most of the study (Appendix I I ) . Monthly p r e c i p i t a t i o n Increased from 1 8 cm i n September 1 9 7 4 to 7 1 cm i n December (Fig. 6 a ) , with a general decrease to August 1 9 7 5 . Seasonal v a r i a t i o n i n freshwater runoff caused d i s t i n c t s a l i n i t y patterns i n the estuary (Fig. 6 c ) . A low s a l i n i t y layer ( 3 m or more) was present during the period.of high runoff. The mean surface s a l i n i t y was ca. 2 - 3 °/oo with an increase of only 1 - 2 °/op over 1 m. A second period of reduced s a l i n i t i e s occurred In November-December concur-rent with a time of high p r e c i p i t a t i o n ( Fig. 6 a , c ) . S a l i n i t y values through the winter were generally high, reaching 27 . 9 °/oo i n January. B. pH, nutrients. Seasonal variations i n pH ranged from 6 . 9 3 (July) to 7 . 9 6 (January) (Fig. 6 b ) . A second minimum was noted i n December during the low s a l i n i t y winter runoff period. The pH i n Snag and P i l e creeks was 0 . 1 to 0 . 2 lower than from the surrounding waters (Fig. 6 b , Appendix I I I ) , with l i t t l e v a r i a t i o n between the creeks. 35 F i g u r e 6 a, b, c. A i r temperature, water temperature, pH, p r e c i p i t a t i o n , and s a l i n i t y June 1974 - Aygust 1975 (data appear i n Appendix I I ) . 35a Hg.6a 36 N i t r a t e , ammonia and ortho-phosphate concentrations i n surface waters adjacent to the delta varied consider-ably. Nitrate reached a high i n January, with low values occurring i n summer and early f a l l (Table 3). Phosphate, less than one tenth the maximum concentration of n i t r a t e , was also highest i n January, whereas ammonia, with a s l i g h t l y higher concentration, was at i t s maximum during May. Nutrient concentrations were generally higher In P i l e and Snag creeks compared to surrounding waters, with seasonal patterns appearing s i m i l a r (Appendix I I I , Table 3). Nutrient concentrations i n the creeks at mid-ebb tide were usually higher than at other tid e times. Nitrate and phosphate concentrations i n P i l e creek, c draining the m i d - i n t e r t i d a l marsh, were higher than those recorded for Snag creek, draining the upper i n t e r -t i d a l marsh. Ammonia concentrations were approximately twice as high i n Snag creek. C. Sediment and organic deposition patterns. Maximum sedimentation occurred during the high runoff period (May-August), with an average of 0.95 + 0.09 cm deposited during the maximum runoff i n June and July. Sedimentation from October to March was low, t o t a l l i n g 0.15 cm. Over the 15 mo study period, 2.05 cm were deposited with an average annual estimated at 1.50 + 0.03 cm. 37 Table 3. Nutrient concentrations Cug-at«l" ) i n surface v waters surrounding the delta (samples taken at high t i d e ) . Date NO3 NHJ PO^ 3 1974 8 August 0.00 0.60 1.86 6 September 0.00 0.00 0.00 22 December 0.79 1.30 0.30 1975 22 January 29.72 0.00 2.09 19 March 15.83 0.00 1.10 30 A p r i l _a 1.14 0.87 14 May 6.14 2.90 0.00 11 June 3.70 0.00 0.02 20 June 2.19 2.56 0.02 9 July 3.10 0.36 0.02 a sample missing 38 Sedimentation and sediment organic content varied s p a t i a l l y and temporally over the delta (Fig. 7). Deposition of sediment was generally greatest i n 1969 and 1970 p r i o r to dyke construction and r e d i r e c t i o n of the r i v e r , averaging 3.2 + 0.3 cm, decreasing towards the upper i n t e r t i d a l zone. Rates of sedimentation noted from 1972 to 1974 were approximately h a l f those noted for the 1970 to 1971 period when r i v e r dredging and land f i l l operations were i n progress. Total sedimenta-t i o n from 1969 to 1974 was greatest at the de l t a front i n Areas A, B, and C, averaging 20 +1 . 3 cm. Lowest sedimentation was recorded i n Area D, with an average of 12.5 cm during the same period. The organic content (mg CO- of sediments In Areas A through D generally decreased with depth (Fig. 7). Area A (low i n t e r t i d a l ) with coarse sand had the lowest organic content. Areas B, C, and D (mid-intertidal) were si m i l a r i n terms of organic content but were about 4 mg C*g dry wt sediment" 1 higher than comparable depths i n the low I n t e r t i d a l zone. Area E, a creek bottom i n the low I n t e r t i d a l zone, had the highest organic content on the d e l t a . D. T i d a l creek flow rates. P i l e creek discharged aa. 703 x 10 J 1 over an ebb tide whereas Snag creek was higher at aa. 810 x 10 1. These values apply only to a complete drainage of the creeks and an adjustment, using tid e tables to account 39 F i g u r e 7. Seasonal p a t t e r n s o f sedimentation and sediment o r g a n i c content as determined from cores taken on the d e l t a at l o c a t i o n s i n d i c a t e d ( s i t e d e s c r i p t i o n s and data appear i n Appendix I V ) . 4 8 12 16 20 * 20->k -OA 15-(mg 10 o 5-18 16-o 3 12-10-© 1766 12 16 20 0 8 T516 20 20 15-10 5-8(H 60 40 204M © 4 8 12 16 20 8 12 16 20 Sediment depth (cm) 20-15-10 120-80-40-© LO 4 8 12 16 20 © 2 4 6 8 10 40 f o r i n c o m p l e t e d r a i n a g e , i s needed t o a r r i v e at more r e a l i s t i c monthly d i s c h a r g e v a l u e s . I I . B i o l o g i c a l F a c t o r s  A. S p e c i e s c o m p o s i t i o n and d i s t r i b u t i o n . B e n t h i c a l g a e p r e s e n t b e l o n g e d t o seven c l a s s e s , showing z o n a t i o n and s u b s t r a t e - h a b i t a t s p e c i f i c i t y w i t h i n t h e i n t e r t i d a l r e g i o n ( T a b l e 4 ) . The rhodo-p h y t e s and d i n o f l a g e l l a t e s were r e s t r i c t e d t o t h e low I n t e r t i d a l w h i l e phaeophytes were d i s t r i b u t e d o v e r t h e low and m i d - i n t e r t i d a l zones a t t h e p e r i p h e r y o f t h e m a r s hland. C h l o r o p h y t e s and cyanophytes o c c u r r e d i n b o t h t h e mid- and upper i n t e r t i d a l r e g i o n s . The c h l o r o -p h y t e s were t h e most common and w i d e l y d i s t r i b u t e d macroalgae on t h e d e l t a w i t h Enteromorpha minima and Monostroma oxyspermwn p r e s e n t a l l y e a r . Cyanophytes, w i t h t h e e x c e p t i o n o f Rivularia biasolettiana w h i c h p e r s i s t e d a t t h e p e r i p h e r y o f t h e d e l t a , o c c u r r e d I n m u l t i s p e c i f i c m i c r o a l g a l a s s o c i a t i o n s i n s m a l l "dead zones" and open areas w i t h i n t h e m a r shland. The cyano-p h y t e s were a l s o found i n a s s o c i a t i o n w i t h xanthophyte mats i n t h e upper i n t e r t i d a l . M acroalgae l i s t e d i n T a b l e % were found as mono-s p e c i f i c growths w i t h some a s s o c i a t e d m i c r o a l g a l e p i p h y t e s ( F i g . 8 a, b ) . M i c r o a l g a l a s s o c i a t i o n s con-s i s t i n g o f diatoms and/or f i l a m e n t o u s c h l o r o p h y t e s were d i s t r i b u t e d o v e r t h e d e l t a . Each a s s o c i a t i o n had a c h a r a c t e r i s t i c appearance i n t h e f i e l d ( F i g . 8 c, d) Table H. Major a l g a l species with t h e i r preferred substrate and location on the del t a . Species Substrate I n t e r t i d a l Area location Chlorophyceae Cladophora sp. Enteromorpha minima (Nag.) ex Kutz. E. p r o l i f e r a (Mull.) J . Ag. Monostroma oxyspermum (Kiitz.) Doty Rhizoolonium implexum ( D i l l . ) Kiitz^ Spirogyra sp. Ulothrix flaeea ( D i l l . ) Thur. Xanthophyceae Vauoheria diohotoma (L.) Ag. V. intermedia Vauoheria spp. ...Continued vascular plants upper logs and p i l i n g s mid-upper sedge soft mud h sediment mid vascular plants mid-upper upper vascular plants upper sedge mid-upper upper t i d a l pools periphery of delta front of delta t i d a l pools and mud bank at periphery of delta adjacent to t i d a l creeks tiidal pools marshland open areas i n sedge marsh Table 4. Continued. Species Substrate Phaeophyceae Fucus d i s t i c h u s logs subsp. edentatus (De La Py.) Powell Laminaria sp. sediment P y l a i e l l a l i t t o r a l i s sedge (Lyng.) K j e l l . Rhodophyceae Antitiiamnion pacificum logs (Harv.) K y l i n Dinophyceae Amphidinium sp. Gymnod-inium sp. -sediment Pevidinium sp. Cyanophyceae R i v u l a r i a b i a s o l e t t i a n a sediment Menegh. ...Continued I n t e r t i d a l Area location low low low-mid low sand f l a t s sand f l a t s delta periphery and front sand f l a t s at delta front low creek banks and sand f l a t s mid-upper bank at periphery of the delta Table 4. Continued. Species Substrate I n t e r t i d a l Area location Calothvix soopulorum Ag. Calothvix spp. Lyngbya a e s t u a r i i (Merr.) Lyngb. O s o i l l a t o v i a brevis (Kutz.) Gom. J-sediment mid-upper 0. tenuis Ag. Phovmidium sp. S p i r u l i n a eubealsa Qejest. Bacillariophyceae (major species only, others appear i n Appendix V) open areas i n sedge marsh Meloeira moniliformis (Mull.) Ag. M. nummuloidee Ag. Naviaula canoellata CI. N. g r e v i l l e i (ag.) CI. Nitz8ohia alosterium (Ehrbg.) W. Sm. Pleurosigma a e s t u a r i i CI, sedge mid sedge mid sediment-consol- low Idated mud sediment-consol- low idated mud sediment-uncon- low solidated mud marsh marsh near t i d a l creek mouths bottom of t i d a l creeks banks of t i d a l creeks F i g u r e 8 a,b. Macroalgae showing g r o s s appearance p f Pylaiella l i t t o r a l i s (A) and Entero-morpha minima ( B ) . 8 c,d. M i c r o a l g a l a s s o c i a t i o n s showing g r o s s appearance o f A s s o c i a t i o n D (C) and F (D). 44 a 45 and was a s s o c i a t e d w i t h a s p e c i f i c s u b s t r a t e and h a b i t a t ( T a b l e 5)- W i t h t h e e x c e p t i o n o f A s s o c i a t i o n s E and G, d i s t r i b u t i o n o f m i c r o a l g a l a s s o c i a t i o n s was g r e a t l y r e s t r i c t e d . Complete l i s t i n g s o f t h e s p e c i e s composi-t i o n s f o r each a s s o c i a t i o n appear i n Appendix V. Enteromorpha minima i s t h e same s p e c i e s r e p o r t e d by Prange (1976) as B l i d i n g i a minima v a r . s u b s a l s a ( K j e l l ) S c a g e l . Some c o n t r o v e r s y e x i s t s as t o whether t h e l a t t e r i s a v a l i d genus. Chapman and Chapman (1973) s t a t e d t h a t t h e r e I s no j u s t i f i c a t i o n f o r t h e r e t e n t i o n , as c h a r a c t e r s used t o i d e n t i f y i t a l s o o c c u r I n t h e genus Enteromorpha ( i . e . p r o s t r a t e d i s c g i v i n g r i s e t o e r e c t p l a n t s , s m a l l c e l l s i z e ) . R e c e n t l y , s e x u a l r e p r o -d u c t i o n , h g i v e n as l a c k i n g i n B l i d i n g i a , has been i d e n -t i f i e d ( T a t e w a k i 1972, Prange 1976) and i s s i m i l a r t o most s p e c i e s o f Enteromorpha. Based on t h e s e f e a t u r e s , t h e e a r l i e r c l a s s i f i c a t i o n o f Enteromorpha i s used i n t h i s t h e s i s . S e a s o n a l changes i n d i s t r i b u t i o n and s p e c i e s comp-o s i t i o n o f b e n t h i c a l g a e were apparent ( T a b l e 6, P i g . 9, Appendix I V ) . Macroalgae such as Enteromorpha minima. Monostroma oxyspermum, Vauoheria dichotoma, and Fucu8 d i s t i o h u s subsp. edentatus, as w e l l as A s s o c i a t i o n s E and P were always p r e s e n t . The remainder were found f o r o n l y a few months and i n d i c a t e d a p a r t i c u l a r s e t o f p h y s i c a l , c h e m i c a l and/or b i o l o g i c a l c o n d i t i o n s . I t i s p r i m a r i l y t h e s e a l g a e w h i c h produce t h e s e a s o n a l d i s t r i -b u t i o n p a t t e r n s n o t e d i n F i g u r e 9, a l o n g w i t h biomass. Table 5. Appearance, composition, and d i s t r i b u t i o n of m u l t i s p e c i f i c microalgal associations. Association Growth form (size) Major species Substrate I n t e r t i d a l location B D G dense brown f i l -amentous clumps (-5.0 cm long) unconsolidated green mat (ca. 2.0 mm thick) Melosira monili-formis M. nummuloides Navicula cancellata red-brown f i l -amentous clumps (^5.0 cm long) l i g h t brown f i l -amentous clumps (^8.0 cm long) brown layer, extensive (ca. 1.0 mm thick) green f e l t -l i k e mat (<0.5 cm thick) green filaments with epiphytes (ca. 2.0 mm thick) Navicula g r e v i l l e i M. nummuloides N. g r e v i l l e i Melosira spp. Navicula spp. Vauoheria dichotoma Vauoheria spp. Ulothrix flacoa sand-mud associ-ated with sedge cons o l i d a t edecl mud i n open areas adjacent to P i l e Creek coarse sand on P i l e Creek bottom consolidated mud, shallow pools unconsolidated mud consolidated mud, sand on dead vascular plants mid low-mid low mid low-mid upper mid-upper T a b l e 6. S e a s o n a l o c c u r r e n c e o f macroalgae and m i c r o a l g a l a s s o c i a t i o n s . 1974 1975 Jun J u l Aug Sep Oct Nov Dec J a n Feb Mar Apr May Jun J u l Aug Macroalgae Cladophora sp. X X X X X X X X Enteromorpha minima X X X X X X X X X X X X X X X Enteromorpha p r o l i f e r a X X X X X X X X X X X Monostroma oxyspermum X X X X X X X X X X X X X X X Rhizoolonium implexum X X X X X X X X X X X X X Spirogyra sp. X X X X X X X X R i v u l a r i a b i a s s o l e t t i a n a X X X X X X X X X X X X X X X P y l a i e l l a l i t t o r a l i s X X X X X X X X Fuous distiohus ssp. edentatus X X X X X X X X X X X X X X X .croalgae A s s o c i a t i o n A X X X X X X X B X X X X X C X X X X X X D X X X X E X X X X X X X X X X X X X X X F X X X X X X X X X X X X X X X G X X X X X T o t a l p r e s e n t 12 11 11 10 8 7 11 12 13 13 12 12 12 11 11 48 F i g u r e 9. T o t a l d i s t r i b u t i o n area and a l g a l biomass. Total biomass (x 10 kg C) 49 Growth p r e s e n t i n t h e f a l l , c h a r a c t e r i z e d by September, cov e r e d ca. 10 x 10-' m ( P i g . 9), w i t h A s s o c i a t i o n E on t h e sand f l a t s a c c o u n t i n g f o r 80%. A l g a e were r e s t r i c t e d t o t h e p e r i p h e r y o f t h e d e l t a , t i d a l p o o l s and open a r e a s a d j a c e n t t o t h e t i d a l c r e e k s ( P i g . 10 a ) . W i n t e r (December) showed a r e d u c t i o n i n t h e number o f c h l o r o p h y t e s p e c i e s and an i n c r e a s e i n m i c r o -a l g a l a s s o c i a t i o n s over t h a t f o r t h e f a l l ( T a b l e 6 ) . D i s t r i b u t i o n was ca. 110 x 1 0 J m ( F i g . 9) w i t h A s s o c i -a t i o n G, dominated by t h e c h l o r o p h y t e Ulothrix flacca, r e s p o n s i b l e f o r 90$ o f t h e coverage ( F i g . 10 B ) . The s p r i n g (March) d i s t r i b u t i o n p a t t e r n was s i m i l a r , w i t h A s s o c i a t i o n s E and G dominant ( F i g . 10 S ) . S p e c i e s d i v e r s i t y was h i g h e s t a t t h i s t i me w i t h reappearance o f c h l o r o p h y t e s and c o n t i n u a t i o n o f m i c r o a l g a l a s s o c i a t i o n s ( T a b l e 6 ) . Summer gr o w t h , c h a r a c t e r i z e d by J u n e , was a g a i n r e s t r i c t e d t o t h e p e r i p h e r y o f t h e d e l t a , t i d a l p o o l s and c r e e k areas as i n t h e f a l l ( F i g . 10 d ) . C h l o r o -p h y t e s dominated over m i c r o a l g a l a s s o c i a t i o n s ( T a b l e 6 ) , o 2 w i t h t o t a l d i s t r i b u t i o n amounting t o ca. 8 x 10 m P i g . 9 ) . B. Biomass and p r o d u c t i o n . S t a n d i n g crop biomass c o n s i d e r e d on a square meter b a s i s i n d i c a t e d Pylaiella l i t t o r a l i s as t h e dominant c o n t r i b u t o r , f o l l o w e d by Enteromorpha minima and t h e c h l o r o p h y t e - d o m i n a t e d A s s o c i a t i o n G ( T a b l e 7). A s s o c i a -t i o n E, dominated by d i a t o m s , had t h e l o w e s t biomass 50 F i g u r e 10. D i s t r i b u t i o n o f b e n t h i c a l g a e on t h e d e l t a i n A) f a l l ( September), B) W i n t e r (December), C) s p r i n g ( M a r c h ) , and D) summer ( J u n e ) . WA m » A m Cladophora sp. Enteromorpha minima Enteromorpha p r o l i f e r a Monostroma oxyspermum Rhizoolonium implexum Spirogyra sp. P y l a i e l l a l i t t o r a l i s A s s o c i a t i o n A B C D E F G 52 Table 7. Maximum biomass values for macroalgae and micro-a l g a l associations. Maximum biomass gC-m"2 P y l a i e l l a l i t t o r a l i s 69.65 Enteromorpha minima 24.83 Association G 17.42 Enteromorpha p r o l i f e r a 17.31 Spirogyr.a sp. 12.00 Cladophora sp. 11.92 Monoetroma oxyspermum 9.04 Association A 8.12 Association D 7.96 Association F 5.72 Rhizoolonium implexum 4.06 Association C 3.92 Association B 3.92 Association E 2.17 53 . _2 v a l u e a t aa. 2.17 g Om . Biomass d e t e r m i n a t i o n s f o r each s a m p l i n g appear i n Appendix V I . T o t a l a l g a l s t a n d i n g crop on t h e d e l t a ranged from aa. 17 kg C I n October t o aa. 1600 kg C i n F e b r u a r y ( F i g . 9). Monthly biomass e s t i m a t e s f o r each macro-a l g a and m i c r o a l g a l a s s o c i a t i o n I n terms o f i t s t o t a l d i s t r i b u t i o n appear i n Appendix V I I . A s s o c i a t i o n G was t h e g r e a t e s t c o n t r i b u t o r t o s t a n d i n g crop b i o m a s s , e s p e c i a l l y i n F e b r u a r y . Other i m p o r t a n t a l g a e were P y l a i e l l a l i t t o r a l i s and A s s o c i a t i o n E, b o t h r e a c h i n g maximum v a l u e s I n A p r i l . These a l g a e were s i g n i f i c a n t i n t h a t they made up o v e r 50% o f t h e . s t a n d i n g crop biomass f o r t h e s e p e r i o d s . Cladophora s p . , Monostroma oxyspermum, and A s s o c i a t i o n s B and C made m i n i m a l c o n t r i b u t i o n s , a v e r a g i n g l e s s t h a n 10% o f t h e t o t a l monthly biomass (Appendix V I I ) . The o r d e r o f dominant net p r i m a r y p r o d u c e r s was d i f f e r e n t t o t h a t n o t e d f o r s t a n d i n g crop biomass ( T a b l e s 7, 8). The most p r o d u c t i v e macroalgae were Spirogyra sp. and Monostroma oxyspermum. Net p r o d u c t i o n maxima f o r m i c r o a l g a l a s s o c i a t i o n s were l o w e r s on t h e a v e r a g e , t h a n t h o s e f o r macroalgae by 50$ o r more (T a b l e 8). A s s o c i a t i o n A was t h e most p r o d u c t i v e and A s s o c i a t i o n D t h e l e a s t . P r i m a r y p r o d u c t i o n over t h e y e a r f o r macro-and m i c r o a l g a e a t 1 m averaged about h a l f t h a t n o t e d a t t h e s u r f a c e (Appendix V I I I ) . However, at t h e time o f maximum r i v e r f l o w , p r o d u c t i v i t y a t 1 m dropped t o between 5 and 20% o f s u r f a c e p r o d u c t i o n . 54 Table 8. Net production maxima and minima recorded. Production (gCm" 2-day" 1) Maxima Minima surface 1 m surface 1 m Macroalgae Spirogyra sp. Monostroma oxyspermum P y l a i e l l a l i t t o r a l i s Enteromorpha minima Cladophora sp. Enteromorpha p r o l i f e r a Rhizoolonium implexum Microalgae Association A P D E C G B 2 .67 0 .68 0 .30 0.12 21 Jun 13 Aug 30 Oct 30 Oct 2 .55 0 .98 0 .35 0 .14 19 Mar 20OFebb 2 Sep 5 J u l 2 .03 0 .67 0 .23 0 .04 19 Mar 19 Mar 20 Jun 21 Jun 1.93 0 .65 0 .13 0 .00 6 Jun 6 Jun 22 Jan 18 Dec 1 .01 0 .44 0 .54 0 .14 19 J u l 27 Aug 12 Jun 12 Jun 0 .94 0 .28 0 .17 0 .07 29 J u l 16 Apr 20 Feb 20 Feb 0 .88 0 .33 0 .12 0 .06 16 J u l 27 Aug 30 Oct 30 Oct 1 .43 0 .38 0 .41 0 .04 29 J u l 14 May 19 J u l 19 J u l 1.08 0 .36 0 .12 0 .02 21 Jun 14 May 18 Dec 18 Dec 0 .72 0 .36 0 .25 0 .15 20 Feb 22 Jan 16 Apr 15 Mar 0 .58 0 .35 0 .02 0 .05 20 Jun 14 May 18 Dec 29 J u l 0 .45 0 .31 0 .14 0 .07 22 Jan 22 Jan 14 May 14 May 0 .35 0 .20 0 .10 0 .05 22 Nov 22 Nov 19 Mar 18 Dec 0 .20 0 .09 0 .10 0 .02 22 Jan 22 Jan 19 Mar 19 Mar 55 The r e d u c t i o n i n d a i l y net p r i m a r y p r o d u c t i o n a s s o c i a t e d w i t h i n c r e a s e d w a t e r depth ( T a b l e 8, Appendix V I I I ) i n d i c a t e d t h e need f o r a c o r r e c t i o n f a c t o r t o get a more a c c u r a t e e s t i m a t e o f monthly net p r o d u c t i o n . A p p l i c a t i o n o f t h e time an a l g a i s exposed (15 cm below s u r f a c e ) and c o v e r e d ( 1 m), as d e t e r m i n e d from t i d e t a b l e s (Appendix I X ) , t o p r o d u c t i o n d a t a p r o v i d e s b e t t e r e s t i m a t e s o f monthly net p r o d u c t i o n t h a n a v e r a g i n g v a l u e s from t h e s u r f a c e and 1 m. V a l u e s thus a r r i v e d a t were c o r r e c t e d f o r d i s t r i b u t i o n ( coverage) a r e a o f -1 -1 a p r o d u c e r and e x p r e s s e d as g C ' d i s t r i b u t i o n a r e a 'mo ( T a b l e 9). These d a t a g i v e b e t t e r e s t i m a t e s o f t h e c o n t r i b u t i o n and i m p o r t a n c e o f a m a c r o a l g a o r m i c r o a l g a l a s s o c i a t i o n t o t h e d e l t a . The a l g a e making th e g r e a t e s t c o n t r i b u t i o n t o t o t a l net p r o d u c t i o n were m i c r o a l g a l A s s o c i a t i o n s G and E, o f which t h e former was by f a r t h e dominant ( T a b l e 9). D u r i n g i t s w i n t e r growth p e r i o d , A s s o c i a t i o n G averaged aa. 74$ o f t h e t o t a l monthly p r o d u c t i o n . P y l a i e l l a l i t t o v a l i s was t h e h i g h e s t m a c r o a l g a l c o n t r i b u t o r , a c c o u n t i n g f o r oa. 18% o f t h e t o t . a l monthly p r o d u c t i o n i n A p r i l . A s s o c i a t i o n s B and C, t h e l o w e s t c o n t r i b u t o r s t o p r o d u c t i o n , a c c o u n t e d f o r 1% o f t o t a l monthly p r o d u c -t i o n ( T a b l e 9). November-March had t h e h i g h e s t net p r o d u c t i o n o v e r t h e s t u d y , w i t h v a l u e s a t o t h e r t i m e s one q u a r t e r t o one h a l f ( T a b l e 9). Table 9. Monthly C net production estimates (gC x 1 0 ° ) for macroalgae and microalgal associations per coverage area, corrected for coverage-exposure time. o o « • *»> ft tt o E O S ' tt Cg rH tt E ,« 4» O tt E E 3 o E Ss is <0 Cu, o CO S Si 5: o tt s> tt> o Cu ft CQ ra E si o o •t* Cu r C E tt tt tt +^  1974 1975 June 3 .16 7. .65 4*1.4 6 .08 20, .oo a 10, .09 4, .74 July 9 • 90 8, .90 6, .16 4 .37 23. .60 15. .35 August 7 .32 5. .12 1, .71 1 .16 19. .07 10, .23 September 1 .55 2, .45 0, .54 1 .32 8, .63 4, .09 October 2, .31 2 .33 2. .40 1, .55 November 1, .21 0 .92 December 0, .33 1 .12 0. ^93 January 0, .22 1 .59 0. .62 1, .34 February 0, .76 0, .12 2 .91 1. .22 10. .07 March 1, .17 0, .39 7 .74 4. .71 37. .69 A p r i l 1. .67 0. .67 7 .25 5. .10 33. .18 May 2 .73 2. .37 1. .63 7 .25 7. .29 30. .32 June 2 .25 2. .05 2. .63 6 .61 24. .60 8. .25 4. .58 July 7 .89 5. .26 4. .38 4 .75 25. .42 13-.64 August 4 .83 3. .34 1. .50 2 .17 22. .48 10. .90 Total 39.62 44.81 23.81 57.58 146.17 92.85 122.85 a assume 20.00 g C minimum net production ...Continued Table 9- Continued. Association A B C D E F G Total 1974 1975 June 17.18 — _ 37.15 18.00 — 128.19 July 3.10 — — 37.13 15.58 - 124.17 August — — — 41.85 7.06 - 93.52 September — - - 67.12 4.65 - 90.35 October _ — 62.39 2.30 — 73.28 November — — — 34.01 13.42 381.60 431.16 December - 0.30 0.08 31.47 1.58 223.26 254.07 January 0.80 0.15 5 .58 97.59 1.98 209.70 319.57 February — 0.87 0.10 10 .11 127.63 3.28 315.90 472.98 March — 0.53 0.11 12 .40 107.42 7.58 289.80 469.54 A p r i l — 0.22 0.06 33 998 121.80 7.34 - 181.22 May 17.55 — 0.04 58.99 12.09 - 140.26 June 16.90 — _ 67.20 13.73 - 148.80 July 11.32 — — 24.78 12.21 - 109.65 August - - - 34.16 6.05 - 85.23 Total 66.05 2.72 0.50 32.07 950.69 124.55 1420.26 58 Three subgroupings o f b e n t h i c a l g a e can be e s t a b l i s h e d w i t h r e f e r e n c e t o t h e t i m e o f d i s t r i b u t i o n and p r o d u c t i o n maxima, i n d i c a t i n g o p t i m a l c o n d i t i o n s ( T a b l e 1 0 ) . Algae most s e n s i t i v e t o h i g h l i g h t , temp-e r a t u r e and d e s s i c a t i o n (low LTD group) a r e p r i m a r i l y phaeophytes and c h r y s o p h y t e s ( d i a t o m s ) . P y l a i e l l a l i t t o r a l i s , diatom-dominated A s s o c i a t i o n s B, C, D, and E, a l o n g w i t h c h l o r o p h y t e - d o m i n a t e d A s s o c i a t i o n G a r e i n t h i s c a t e g o r y . Less s e n s i t i v e s p e c i e s are i n t h e h i g h LTD c a t e g o r y and I n c l u d e t h e xanthophyte Vauoheria ( A s s o c i a t i o n P) and o t h e r c h l o r o p h y t e s p e c i e s except Monostroma oxyspevmum, w h i c h I s p l a c e d i n a s e p a r a t e group as a medium LTD s p e c i e s . 14 C. Comparison o f C and d i s s o l v e d oxygen p r i m a r y p r o d u c t i o n e s t i m a t e s . 14 Comparison o f C net p r i m a r y p r o d u c t i o n e s t i m a t e s w i t h t h o s e from t h e oxygen method show the former t o be h i g h e r by an average o f 8.8% ( T a b l e 10!). 14 The C v a l u e s o f net p r i m a r y p r o d u c t i o n as p e r c e n t o f g r o s s p r i m a r y p r o d u c t i o n v a r i e d , w i t h each a l g a t e s t e d ( T a b l e 1 1 ) . C h l o r o p h y t e s had somewhat h i g h e r v a l u e s t h a n d i d t h e d i a t o m a s s o c i a t i o n s , r a n g i n g from 64.7 - 86.1$, w i t h an average o f 76%. E s t i m a t e s f o r a s s o c i a t i o n s were 70 - 82%, w i t h an average o f 75%, whereas Pylaiella l i t t o r a l i e was l o w e r a t 68.5%. 59 T a b l e 10. Net p r i m a r y p r o d u c t i o n o f macroalgae and m i c r o -—2 —1 a l g a l a s s o c i a t i o n s on t h e d e l t a (g C*m .day ). S p e c i e s Low LTD group P y l a i e l l a l i t t o r a l i s A s s o c i a t i o n D A s s o c i a t i o n C A s s o c i a t i o n G A s s o c i a t i o n B Medium LTD group Monostroma oxyspermum H i g h LTD group Spirogyra sp. Enteromorpha minima A s s o c i a t i o n A A s s o c i a t i o n F Cladophora sp. Enteromorpha p r o l i f e r a Rhizoclonium implexum A s s o c i a t i o n E Maxima Month 2.03 0.72 0.45 0.33 0.20 March F e b r u a r y January November Ja n u a r y 2.55 March 2.67 1.93 1.43 1.08 1.01 0.94 0.88 00.58 June June J u l y June J u l y J u l y J u l y June 60 Table 11. C production as percent oxygen production (averages of 10 determinations). percent 0- percent above 0 b e gross production net production Macroalgae Cladophora sp. 78.0 6.7 Enteromorpha minima 75.4 9.1 Enteromorpha p r o l i f era 73.8 7.3 Monostroma oxyspermum 86.1 10.2 Spirogyra sp. 64.7 7.4 Rhizoolonium implexum 78.2 10.7 P y l a i e l l a l i t t o r a l i e 68.5 11.3 Microalgae Association A 75.6 9-7 B 74.1 5.8 C 71.4 7.6 D 78.0 8.4 E 73.0 10.9 F 70.0 5.1 G 82.2 12.4 Mean 8.8 corrected for organic exudation 14 C net production engross production 14 C net production Op net production 61 D. D i s s o l v e d o r g a n i c m a t e r i a l (DOM) exuded d u r i n g p r o d u c t i o n . D i s s o l v e d o r g a n i c m a t e r i a l exuded by b e n t h i c a l g a e amounted t o between 0 and 30% o f t o t a l net p r o d u c t i o n ( T a b l e 1 2 ) . C h l o r o p h y t e s had t h e l o w e s t v a l u e s and P y l a i e l l a l i t t o r a l i s and A s s o c i a t i o n B t h e h i g h e s t e x u d a t i o n . A l l m i c r o a l g a l a s s o c i a t i o n s had r e a s o n a b l y h i g h r a t e s . The time o f e x u d a t i o n maxima v a r i e d , w i t h June o r J u l y t h e most common ( T a b l e 1 2 ) . E. A d d i t i o n and removal o f p a r t i c u l a t e o r g a n i c m a t t e r (POM). P a r t i c u l a t e o r g a n i c m a t t e r ( > 0.45/^diameter) d e p o s i t e d on and removed from t h e d e l t a o v e r a t i d a l c y c l e c o n s i s t e d o f p h y t o p l a n k t o n , b e n t h i c macroalgae and m i c r o a l g a e and d e t r i t a l m a t e r i a l . A d d i t i o n . S p e c i e s c o m p o s i t i o n o f t h e added o r g a n i c m a t t e r changed s e a s o n a l l y . P P l a n k t o n i c diatoms o r i g i n -a t i n g from Howe Sound ( S t o c k n e r and C l i f f 1976) and t h e Squamish R i v e r were n o t e d a t each s a m p l i n g . The marine Thalassiosira pao-ifioa and Skeletonema aoetatum dominated i n March and A p r i l as d i d Chaetoaeros sp. and t h r e e s p e c i e s o f d i n o f l a g e l l a t e s . B e n t h i c d i a t o m s , dominated by Navioula eaneellata* a p p a r e n t l y l i f t e d from t h e d e l t a and r e t u r n e d on t h e s u c c e e d i n g ebb t i d e , were most abundant from December t o June. B e n t h i c m a c r o a l g a e , a l s o l i f t e d from t h e d e l t a , were most p r e v a l e n t from 62 Table 12. Organic exudation as percent t o t a l net primary production measured by the C method. Depth Exudation Time of (m) Range Ave. maximum Cladophora sp. o a 4-10 7 June 1 2-9 6 July Enteromorpha minima 0 4-10 7 June 1 4-9 5 November Enteromorpha p r o l i f e r a 0 4-19 7 July 1 3-12 6 August Monostroma oxyspermum 0 4-8 6 July 1 4-13 9 June Spirogyra sp. 0 9-20 13 June 1 5-16 15 October Rhizoolonium implexum 0 0-16 8 July 1 3-11 8 July P y l a i e l l a l i t t o r a l i s 0 14-30 22 June 1 3-13 7 June Microalgae Association A 0 10-28 19 July 1 4-20 7 July B 0 10-30 20 December 1 0-20 16 December C 0 4-18 13 January 1 0-9 8 December D 0 7-16 13 A p r i l 1 5-6 6 February E 0 8-25 15 June 1 4-20 11 July F 0 5-24 12 June 1 0-17 10 July G 0 5-22 10 February 1 5-7 6 February a15 cm below water surface 63 F i g u r e 11. P a r t i c u l a t e o r g a n i c matter added to the d e l t a expressed as percent d e t r i t u s (^) , microalgae , and macroalgae (???) • (average o f f o u r s t a t i o n s ) A. Marshland B. Sand/mud f l a t s 63a 64 October t o A p r i l , w i t h Rhizoclonium implexum and P y l a i e l l a l i t t o r a l i s t h e main s p e c i e s . S p a t i a l and t e m p o r a l v a r i a t i o n s i n d e p o s i t i o n o f POM e x i s t e d between.the sand/mud f l a t s and t h e marshland ( F i g . 1 1 ) . On t h e m a r s h l a n d , macroalgae were l o w e s t i n O c t o b e r - J a n u a r y , w i t h v a l u e s f o u r t i m e s h i g h e r i n A p r i l and May. M i c r o a l g a e accounted f o r ca. 20% o f t h e t o t a l o r g a n i c d e p o s i t i o n , r i s i n g t o 40$ i n March. The p e r c e n t a d d i t i o n o f d e t r i t a l m a t e r i a l was g r e a t e s t d u r i n g t h e summer arid f a l l , a v e r a g i n g about 50% ( F i g . 1 1 ) . The c o m p o s i t i o n of.POM added t o sand/mud f l a t s i n the low i n t e r t i d a l p r o v e d somewhat more v a r i a b l e t h a n t h e m a r s h l a n d ( F i g . 1 1 ) . Macroalgae c o n t r i b u t e d l e a s t (ca. 1 1 $ ) , b e i n g g r e a t e s t i n A p r i l . M i c r o a l g a e averaged 23$. D e t r i t a l m a t e r i a l washed from the m a r s h l a n d , as jud g e d from s p e c i e s c o m p o s i t i o n , and d e p o s i t e d on t h e sand/mud f l a t s made up ca. 60% o f t h e t o t a l o r g a n i c -2 m a t t e r d e p o s i t e d . A d d i t i o n o f o r g a n i c m a t t e r (g C*m d a y " 1 ) was g e n e r a l l y 50% h i g h e r I n t h e marshlan d ( T a b l e 1 3 ) . Removal. S e a s o n a l v a r i a t i o n s I n POM l e a v i n g t h e d e l t a v i a t i d a l c r e e k s were d i f f e r e n t f o r Snag and P i l e c r e e k s ( F i g . 1 2 ) . I n E l l e c r e e k , P y l a i e l l a l i t t o r a l i a ( A p r i l - M a y ) , Rhizoclonium implexum (June) and Entero-morpha prolif'era (August-September) were r e c o r d e d as abundant. The l o w e s t m a c r o a l g a l c o m p o s i t i o n was I n November (8$) and t h e h i g h e s t i n A p r i l (50$) ( F i g . 1 2 ) . The s p e c i e s noted f o r P i l e were a l s o common i n Snag c r e e k but i n lo w e r amounts, making up a maximum o f ca. 65 Table 13. Addition of pa r t i c u l a t e organic matter to the delta (mg C«m ) (mean of 4 sampling s i t e s i n each area, sampling period over 1 t i d a l c y c l e ) . Month Marshland Sand/mud f l a t s 1974 June 76 31 July 92 40 August 112 60 September 64 29 October 42 27 November 32 18 December 4 2 1975 January 10 5 February 30 18 March 120 3'4 A p r i l 150 40 May 139 37 June 92 38 July 89 34 August 104 30 66 F i g u r e 12. P a r t i c u l a t e o r g a n i c matter removed through Snag and P i l e creeks as percent d e t r i t u s (^) , microalgae , and m a c r o a l g a e ^ ) , (composite o f data from h i g n and low creek l e v e l s ) . A. ) Snag creek B. ) P i l e creek 66a 67 25%. M i c r o a l g a e ( d i a t o m s ) r e c o r d e d from b o t h c r e e k s i n h i g h numbers were Melosira spp. and Navicula spp. The removal o f m i c r o a l g a e showed b a s i c a l l y t h e same s e a s o n a l p a t t e r n s as macroalgae w i t h November and A p r i l b e i n g t h e h i g h p e r i o d s i n b o t h c r e e k s . D e t i r l t a l m a t e r i a l i n Snag c r e e k was h i g h e r t h a n t h a t r e c o r d e d from P i l e c r e e k , r e a c h i n g ca. 80% i n J a n u a r y . The p a r t i c u l a t e o r g a n i c c o n t e n t o f waters d r a i n i n g t h e c r e e k s was h i g h e r ( g r e a t e r t h a n 60%) when t h e wat e r l e v e l was j u s t below t h e d e l t a s u r f a c e compared t o when i t r e a c h e d t h e c r e e k bottoms ( T a b l e 1 4 ) . E s t i m a t e s o f POM and n u t r i e n t removal from P i l e c r e e k may r e p r e s e n t o v e r e s t i m a t e s c o r r e c t e d t o some e x t e n t by removing background c o n c e n t r a t i o n s . S i n c e t h e a r e a e a s t o f t h e c r e e k a t t h e d e l t a f r o n t ( P i g . 2) i s at a lo w e r e l e v a t i o n , w a t e r not d r a i n i n g cJff t h e d e l t a i s b rought i n and i n c l u d e d i n t h a t sampled. However, placement o f t h e s a m p l i n g s t a t i o n a t t h e d e l t a f r o n t r a t h e r t h a n f a r t h e r up t h e c r e e k whereeeO>evatdjo.ns'«were e q u a l on b o t h s i d e s . was c o n s i d e r e d b e s t as t h e l a t t e r would r e s u l t i n a c o n s i d e r a b l e u n d e r e s t i m a t e by o n l y m o n i t o r i n g a p a r t o f t h e d e l t a s u r f a c e . The s p e c i e s c o m p o s i t i o n o f i d e n t i f i a b l e o r g a n i c m a t t e r removed from t h e d e l t a s u r f a c e i n f l o o d t i d e was d i r e c t l y r e l a t e d t o l o c a t i o n o f s a m p l i n g s i t e and time o f y e a r . A l g a e most r e a d i l y removed were f i l a m e n t o u s forms (Pylaiella l i t t o r a l i s 3 Enteromorpha prolifera3 Ulothrix flacca) a l o n g w i t h d i a t o m dominated m i c r o a l g a l 68 Table , Ik. Particulate organic matter removed from the delta by Snag and P i l e Creeks (mgC'l - 1) at high and low water levels 3". Snag Creek P i l e Creek High Low Ave. High Low Ave. 1974 June 21 .9 15. .3 18. .6 24. .2 12 .7 18 .4 July 20 .2 15. .4 17. .8 21. .1 11 .4 16 .3 August 20 .0 15. .2 17. .6 17. .4 13 .1 15 .3 September 17 .1 8, .7 12. .9 15. .2 14 .1 14 .7 October 16 .5 7. .2 11. .9 17. ,1 9 .7 13 .4 November 11 .7 8, .7 10. .2 18. ,2 9 .5 13 .9 December T5 January 6 .9 4, .9 5. .9 8. .9 5 .7 7 .3 11 .4 5, .7 8. .6 13. .9 4 .1 9 .0 February 23 .7 15. .8 19. .8 19. .4 12 .0 15 .7 March 24 .7 17. .0 20, .9 25. .4 17 .9 21 .7 A p r i l 19 .1 10, .1 14, .6 17. .1 8 .7 12 .9 May 15 .3 12, .0 13. .7 21, .9 12 .0 16 .9 June 20 .4 17, .2 18, .8 22, .7 15 .2 18 .9 July 20 .0 14, .7 17, .4 27, .2 14 .9 21 .1 August 19 .9 14, .9 17, .4 17. .2 10 .8 14 .0 a h i g h water l e v e l ca. 15 cm below delta surface; low water l e v e l near creek bottom. 69 a s s o c i a t i o n s . The g r e a t e s t abundance o f each was r e c o r d e d a t t h e end o f i t s growth p e r i o d . The amount removed was a l s o dependent upon s i t e and time o f y e a r ( T a b l e 15). Removal r a t e s from sand/mud f l a t s were l o w e s t i n Julyy 1974. S e d g e - f r e e a r e a s i n t h e mid- and upper i n t e r t i d a l had removal r a t e s c o n s i d e r -a b l y h i g h e r t h a n t h e sand/mud f l a t s . V a l u e s v a r i e d w i t h t h e m i d - i n t e r t i d a l removal r a t e s more t h a n t w i c e t h e upper i n t e r t i d a l a t c e r t a i n t i m e s o f t h e y e a r , r e a c h i n g h i g h s i n March ( T a b l e 15). The m a r s h l a n d had g e n e r a l l y h i g h e r v a l u e s w i t h maximum removal i n March, f a l l i n g t o a low i n November. F. C a l o r i c e q u i v a l e n t s . C a l o r i c e q u i v a l e n t s ( k c a l ' g o r g a n i c - 1 ) f o r macro-a l g a e were g e n e r a l l y l o w e r t h a n t h o s e o f t h e d i a t o m dominated m i c r o a l g a l a s s o c i a t i o n s ( T a b l e 16). A s s o c i a -t i o n s dominated fey Vaucheria (F) and Ulothrix (G) a l s o had low v a l u e s . The c a l o r i c c o n t e n t o f sediments v a r i e d c o n s i d e r a b l y as a f u n c t i o n o f sediment t y p e , l o c a t i o n w i t h i n t h e i n t e r t i d a l zone and t h e s p e c i e s o f v a s c u l a r p l a n t I n t h e a r e a ( T a b l e 16). Sediment A r e a F had t h e g r e a t e s t c a l o r i c c o n t e n t and A r e a G t h e l e a s t . D e t r i t a l m a t e r i a l from t h e d e l t a averaged a c a l o r i c c o n t e n t s i m i l a r t o some d i a t o m a s s o c i a t i o n s . M a t e r i a l removed from and added t o t h e d e l t a a l s o had h i g h c a l o r i c v a l u e s i n t h e s p r i n g and summer p e r i o d . F a l l - w i n t e r v a l u e s were l o w e r by more t h a n 1 k c a l - g o r g a n i c - 1 ! 70 Table 15, Particulate organic matter (mgOm~ -flood t i d e " ) removed from the major habitat types on the de l t a . Sand/mud f l a t s Marshland Marshland (sedge-free) (Carex meadow) mid upper 1974 June 27.5 July 18.5 August 24.5 September 23.5 October 28.0 November 26.5 December 22.5 1975 January 35.0 February - a March 53.0 A p r i l 51.0 May 37.5 June 27.5 July 22.0 August 20.0 163.5 98.0 268.4 201.5 113.0 261.7 191.0 115.0 268.6 184.0 113.0 204.0 153.0 118.5 199.6 136.0 114.5 194.4 216.0 121.5 253.4 296.0 127.0 305.3 _a _a _a 362.0 168.5 337.4 218.0 98.0 239.0 178.5 105.5 230.4 288.5 108.5 266.0 206.0 98.5 259.9 216.5 109.5 251.4 a data missing 71 Table 1$, Caloric equivalents f o r algae, sediments, d e t r i t u s , and POM. Material No. %LOI kcal* kcal* g dry wt" 1 g organic Cladophora sp. 5 52, .9 2. ,24 4 .32 + 0 .18 Enteromorpha minima 10 74 .2 3. .05 4 .84 + 0 .09 Enteromorpha p r o l i f e r a 5 63 .1 3. ,01 4 .49 + 0 .05 Mono8troma oxyspermum 10 89 .9 3. ,06 4 .29 + 0 .04 Spirogyra sp. 5 91 .2 3. .64. 3 .99 + 0 .10 Rhizoclonium implexum 10 74 .8 3. .49 4 .65 + 0 .23 P y l a i e l l a l i t t o r a l i s 10 73 .0 3. .41 4 .67 + 0 .07 Association A 5 53 .1 2. .61 4 .92 + 0 .19 B 5 50 .2 2. .57 5 .12 + 0 .23 C 5 59 .1 2. .98 5 .04 + 0 .17 D 5 60 .2 3. .09 5 .13 + 0 .10 E 5 41 .9 2. .62 6 .25 + 0 .05 F 3 75 .9 3. .02 3 .98 + 0 .09 G 3 80 .1 3. .13 3 .91 + 0 .09 Sediment Area A 5 11 .2 0, .51 4 .55 + 0 .05 B 6 17 .7 0, .91 5 .14 + 0 .21 C 5 15 .3 0, .79 5 .16 + 0 .14 D 6 42 .5 1, .79 4 .21 + 0 .18 E 6 46 .9 2, .39 5 .09 + 0 .20 P 4 18 .9 1. .08 5 • 71 + 0 .12 G 5 49 .1 1, .93 3 .91 + 0 .10 Detritus 8 50 .8 3 .07 6 .04 + 0 .39 Removed organic matter .83 March-August 5 48 .0 3 .28 6 + 0 .37 September-February 5 59 .3 3 .00 5 .05 + 0 .27 Added organic matter .56 March-August 5 45 .0 2 .95 6 + 0 .29 September-February 5 51 .0 2 .72 5 .33 + 0 .14 Carex lyngbyei .49 .08 Intact 3 85 .5 3 4 + 0 .10 Decomposed 3 71 .4 2 .95 4 .13 + 0 .09 72 G. B e n t h i c a l g a e , v a s c u l a r p l a n t , d e t r i t u s u t i l i z a t i o n  by amphipods. p W i t h i n t h e 30 x 30 m g r i d sampled a t low t i d e amphipods were noted i n k6% o f t h e e x a m i n a t i o n p o i n t s , and o f t h e s e , macroalgae were used as c o v e r 90% o f the t i m e . A n a l y s i s o f d a t a c o l l e c t e d showed a v e r y s t a t i s t i c a l l y s i g n i f i c a n t r e l a t i o n s h i p between amphipods and P y l a i e l l a l i t t o r a l i s , a f i l a m e n t o u s brown a l g a ( T a b l e 17). R e l a t i o n s h i p o f Enteromorpha minima and amphipods was a l s o s i g n i f i c a n t but t o a much l o w e r d e g r e e , whereas t h e a s s o c i a t i o n w i t h Monostroma oxysper-mum was not s i g n i f i c a n t . A d u l t and j u v e n i l e amphipods t e s t e d i n t h e l a b o r -a t o r y p r e f e r r e d f i l a m e n t o u s a l g a e f o r c o v e r , w i t h P. l i t t o r a l i s r a n k i n g h i g h e s t , as i n t h e f i e l d ( T a b l e 18). A d u l t amphipods chose E. minima and M. oxyspermum more o f t e n t h a n d i d t h e j u v e n i l e s who p r e f e r r e d d i a t o m a s s o c i a t i o n s and d e t r i t u s . Carex shoots were chosen l e a s t by b o t h g r o u p s . C a r e f u l e x a m i n a t i o n i n t h e f i e l d i n d i c a t e d t h a t a c t i v e f e e d i n g o c c u r r e d by b o t h a d u l t and J u v e n i l e amphipods a s s o c i a t e d w i t h P. l i t t o r a l i s and E. minima when submerged a t low t i d e i n p o o l s . L a b o r a t o r y s t u d i e s on f e e d i n g showed t h e same p r e f e r e n c e f o r P. l i t t o r a l i s by a d u l t s and j u v e n i l e s ( T a b l e 18). As w i t h c o v e r , a d u l t s s e l e c t e d E. minima and M. oxyspermum more o f t e n then t h e j u v e n i l e s who chose t h e m i c r o a l g a l a s s o c i a t i o n 73 Table 1$. Results of analysis using a 2 x 2 contingency table showing relat i o n s h i p of macroalgae and amphipods i n a 30 x 30 m g r i d on the marshland at low t i d e . (TabulatedX 2 = 3.84 at P Q Q [ . ) . a Associated algae o "Y^ computed Pylaiella l i t t o r a l i s 43.79* Enteromorpha minima 4.46* Monostroma oxyspermum 2.66 indicates significance Table 18. Cover and feeding preference shown by amphipods tested i n the laboratory ( t o t a l of 300 adult or juvenile amphipods - 15 t r i a l s of 20 each). Source Cover Feeding Adult Juvenile Adult Juvenile Vylaiella l i t t o r a l i a 138 156 122 145 Enteromorpha minima 102 69 91 31 Mono8troma oxyapermum 24 12 31 16 Association A 6 14 10 25 Detritus 25 44 46 79 Carex lyngbyei 5 5 0 4 (partly decayed brown shoots) 75 and d e t r i t u s . A g a i n , sedge shoots were not used as a f o o d s o u r c e except by j u v e n i l e s when g r e a t l y decayed. A n a l y s e s o f gut c o n t e n t s from amphipods i n c o n t r o l l e d f e e d i n g e x periments showed a c h a r a c t e r i s t i c c o l o r and i n some cases i t was p o s s i b l e t o l o c a t e i n t a c t fragments o f a l g a e . However, i t was i m p o s s i b l e t o r e l a t e gut c o n t e n t s from amphipods c o l l e c t e d I n t h e f i e l d t o a p a r t i c u l a r f o o d s o u r c e even though they were found f e e d -i n g on i t a t t h e t ime o f c o l l e c t i o n . The f a t t y a c i d a n a l y s i s t e c h n i q u e d i d g i v e some i n d i c a t i o n o f f o o d u t i l -i z a t i o n i n t h e f i e l d . The a l g a e and d e t r i t u s t e s t e d had c h a r a c t e r i s t i c f a t t y a c i d s , as d e t e r m i n e d by t h e t ime i n sec t o a peak ( T a b l e 19). The number o f f a t t y a c i d peaks which appear t o be unique t o any s p e c i e s v a r i e s and c e r t a i n l y can be i d e n t i f i e d i n t h e f a t t y a c i d spectrum o f amphipods f e d on a s p e c i f i c a l g a . I n each o f t h e m a c r o a l g a e , two f a t t y a c i d s c o u l d be t r a c e d . I n a d d i t i o n , f a t t y a c i d peaks o f t h e d e t r i t a l m a t e r i a l c o u l d be l o c a t e d i n amphipods u s i n g t h i s as a f o o d s o u r c e . A n a l y s i s o f amphipods c o l l e c t e d w h i l e a c t i v e l y f e e d i n g i n t h e f i e l d i n d i c a t e d two f a t t y a c i d peaks which c o u l d be t r a c e d back t o Enteromorpha minima* P y l a i e l l a l i t t o r a l i s and d e t r i t a l m a t e r i a l . The peaks a t t r i b u t e d t o d e t r i t u s were somewhat h i g h e r and o f 76 T a b l e 1 9 . F a t t y a c i d a n a l y s i s o f s e l e c t e d f o o d s o u r c e s and amphipods f e d on them. Food s o u r c e Time t o peak (s ) Amphipods u s i n g f o o d s o u r c e , time t o peak (s) Monostroma oxyspermum Pylaiella l i t t o r a l i s Enteromorpha minima A s s o c i a t i o n A F i e l d d e t r i t u s F a t t y a c i d peak from amphipods f e e d i n g i n th e f i e l d 1 7 7 * 820* 973* 230* 460* 123 130 147 388* 525* 1 6 1 * 5 9 0 * 136* 1 7 1 * 410* 466* 490* 5 5 0 * 173* 214 252 817* 183 237* 459* 627 135 151 386* 522* n i l 119 134* 142* 174* 408* 493* 590 170*D* 234*P 3 8 4 * E 468*P 493*D 527*E 553*D 813*M " c h a r a c t e r i s t i c f a t t y a c i d peak f o r a f o o d s o u r c e (+ 5 s d i f f e r e n c e ) a l e t t e r s i n d i c a t e peaks I n f i e l d f e d amphipods w h i c h c o r r e s p o n d t o th o s e found i n d e t r i t u s ( D ) , Enteromorpha ( E ) , Pylaiella ( P ) , and Monostroma ( M ) . 77 l o n g e r d u r a t i o n i n comparison t o t h o s e o f I n t a c t a l g a e . Thus, i t appears t h a t d e t r i t u s may be t h e f a v o r e d f o o d s o u r c e f o r amphipods. I I I . S t a t i s t i c a l A n a l y s i s o f F a c t o r s I n f l u e n c i n g P r i m a r y P r o d u c t i o n R e s u l t s o f a p r e v i o u s s t u d y u s i n g s i m p l e l i n e a r r e g r e s s i o n suggest s a l i n i t y , t e m p e r a t u r e and l i g h t s i g n i f i c a n t i n l i m i t i n g p r i m a r y p r o d u c t i o n a t Squamish, (Pomeroy and S t o c k n e r 1976). E x t e n d i n g t h i s , s t e p w i s e m u l t i p l e r e g r e s s i o n ( 'TRIP) was r u n t o t e s t t h e combined e f f e c t o f t h e s e t h r e e f a c t o r s p l u s n u t r i e n t s on net p r o d u c t i o n t o p o i n t out t h e most l i k e l y f a c t o r s i n -f l u e n c i n g each a l g a v - T h i s approach i s n e c e s s a r y as f l u c t u a t i o n s i n p r o d u c t i o n cannot be a t t r i b u t e d t o a s i n g l e f a c t o r o r cause. F o r m a c r o a l g a e , l i g h t and t e m p e r a t u r e s t r o n g l y I n -f l u e n c e net p r o d u c t i o n (Table. 20). Phosphate and s a l i n i t y a r e i m p o r t a n t t o a l e s s e r degrees? C o r r e l a t i o n s are p o s i t i v e w i t h t h e e x c e p t i o n o f s a l i n i t y w h i c h i s neg-a t i v e f o r Spivogyra s p . , a f r e s h w a t e r a l g a . M i c r o a l g a l a s s o c i a t i o n s , a s i d e from E and F, were p r e s e n t f o r a s h o r t t i m e . T h i s r e s u l t e d i n sample s i z e s not l a r g e enough t o p r o v i d e good a n a l y s e s a t t h e p r o b a b i l i t y l e v e l used (p=0.05). However, e x a m i n a t i o n o f t h e c o r r e l a t i o n m a t r i x i n d i c a t e s t h a t e i t h e r temp-e r a t u r e o r l i g h t may i n f l u e n c e net p r o d u c t i o n o f t h e s e . 78 Table 20. S t a t i s t i c a l analysis of primary production data using stepwise multiple regression (p = 0.05). Dependent variable = net production, independent variables = s a l i n i t y , l i g h t , temperature, n i t r a t e , phosphate, and ammonia. Factor Individual Combined F prob F prob RSQ Cladophora sp. Enteromorpha minima E. prolifera Monostroma oxyspermum Rhizoolonium implexum Spirogyra sp. Association E Association F l i g h t P O 4 l i g h t temperature l i g h t l i g h t temperature l i g h t s a l i n i t y l i g h t l i g h t temperature s a l i n i t y temperature 0.0002 0.0095 0.0005 0.0027 0.0004 0.0360 0.0019 0.0002 0.0078 0.0075 0.0000 0.0009 0.0085 0.0042 0.0079 0.0004 0.7620 0.0009 0.7993 0.0004 0.6629 0.0067 0.4658 0.0006 0.5112 0.0000 0.8842 0.0007 0.6943 0.0014 0.4699 79 DISCUSSION C o n s i d e r a t i o n must be g i v e n t o s t r u c t u r a l and f u n c t i o n a l a s p e c t s i n a t t e m p t i n g t o u n d e r s t a n d any ecosystem. A n a l y s i s o f ecosystem s t r u c t u r e o r o r g a n -i z a t i o n ( s p a t i a l d i s t r i b u t i o n o f components, t h e i r abundance o r coverage a r e a , s p e c i e s c o m p o s i t i o n p l u s c o n t r o l l i n g p h y s i c a l , c h e m i c a l and b i o l o g i c a l f a c t o r s ) p r o v i d e s a b a s i s f o r i n t e r p r e t i n g t h e more dynamic o r f u n c t i o n a l s i d e o f an ecosystem. F u n c t i o n i s b e s t r e v e a l e d t h r o u g h t h e f l o w o f energy and m a t e r i a l s and i s c h a r a c t e r i s t i c o f a p a r t i c u l a r ecosystem. The f o l l o w i n g d i s c u s s i o n r e p r e s e n t s a s t r u c t u r e -f u n c t i o n a n a l y s i s o f t h e a u t o t r o p h i c components ( v a s -c u l a r p l a n t s and b e n t h i c a l g a e ) o f the Squamish d e l t a . O p e r a t i o n o f t h i s l e v e l o f t h e ecosystem and i t s r e s -ponse t o e n v i r o n m e n t a l change are s i g n i f i c a n t and have c o n s i d e r a b l e i n f l u e n c e o v e r h e t e r o t r o p h i c components. I t i s a n e c e s s a r y f i r s t s t e p i n t h e u n d e r s t a n d i n g o f o v e r a l l ecosystem f u n c t i o n . I . Ecosystem S t r u c t u r e Ecosystem s t r u c t u r e I n an e s t u a r y i s r e g u l a t e d by p r i m a r y f a c t o r s w h i c h g o v e r n e n t r y o f a s p e c i e s and by secondary f a c t o r s w h i c h d e t e r m i n e e s t a b l i s h m e n t and s p a t i a l - t e m p o r a l p a t t e r n s o f d i s t r i b u t i o n . F a c t o r s a f f e c t i n g t h e s e are a l s o s i g n i f i c a n t i n c o n t r o l l i n g p r i m a r y p r o d u c t i o n as w i l l l b e d i s c u s s e d . S t r u c t u r e o f 80 t h e b e n t h i c a l g a l community w i l l be c o n s i d e r e d f i r s t , f o l l o w e d by t h a t o f t h e v a s c u l a r p l a n t s . Osmoregulatory c a p a b i l i t y (degree o f e u r y h a l i n i t y ) i s t h e p r i m a r y f a c t o r c o n t r o l l i n g e n t r y o f an a l g a i n t o t h e Squamish e s t u a r y . A n o t a b l e f e a t u r e o f a l g a l f l o r a on t h e d e l t a i s s l a c k o f s p e c i e s r i c h n e s s , w i t h p r i m a r i l y c h l o r o p h y t e s and diatoms p r e s e n t . T h i s I s i n c o n t r a s t t o o t h e r c o a s t a l i n t e r t i d a l h a b i t a t s such as r o c k y marine shores ( L i t t l e r and Murray 1974) and c o a s t a l p l a i n e s t u a r i e s (Foreman 1975) w i t h a g r e a t e r abundance o f phaeophytes and r h o d o p h y t e s . Impoverishment and s p e c i e s v a r i a t i o n r e f l e c t s t h e i n a b i l i t y o f many common i n t e r t i d a l marine s p e c i e s t o e n t e r and s u r v i v e i n a r e a s o f r e d u c e d s a l i n i t y . The g r a d u a l drop i n marine s p e c i e s t h r o u g h r e g i o n s o f l e s s s a l i n e w a t e r s has been commonly no t e d (Doty and Newhouse 1954, Z a n e v e l d 1969, Remane and S c h l e l p e r 1971). At Squamish t h i s r e s u l t s i n a a t y p i c a l " e s t u a r i n e a l g a l community s t r u c t u r e c o n s i s t -i n g o f a m i x t u r e o f low s a l i n i t y t o l e r a n t s p e c i e s coming from the sea (Fuoue3 laminariaa Pylaiella), s e v e r a l a l g a e common and;sometimes r e s t r i c t e d t o e s t u a r i e s (Enteromorpha 3 Rhizoolonium* Vauoheria and d i a t o m s ) , p l u s a v e r y few f r e s h w a t e r s p e c i e s (Spirogyra* Cladophora). The e s t a b l i s h m e n t of, an a l g a p h y s i o l o g i c a l l y a b l e t o e n t e r the Squamish e s t u a r y i s dependent upon the I n t e r a c t i o n o f secondary f a c t o r s - p h y s i c a l , c h e m i c a l and 81 b i o l o g i c a l i n n a t u r e - which v a r y o v e r t h e y e a r . The r e s u l t i s s e a s o n a l s p e c i e s p a t t e r n s and a l t e r e d eco-system s t r u c t u r e . A l g a l s u b s t r a t e and h a b i t a t p r e f e r e n c e , e v i d e n t a t Squamish ( T a b l e s 4,5) i s i m p o r t a n t i n d e t e r m i n i n g s p a t i a l - t e m p o r a l d i s t r i b u t i o n p a t t e r n s . The e f f e c t o f s u b s t r a t e on a l g a l c o l o n i z a t i o n has been i n v e s t i g a t -ed u s i n g a number o f a r t i f i c i a l s u b s t r a t e s i n c l u d i n g p l a s t i c ( R i s k 1973, H a r l i n 1973) and c o n c r e t e ( F o s t e r 1975). The g e n e r a l c o n c l u s i o n i s t h a t f i n e r t e x t u r e d s u r f a c e s a r e l e s s f a v o r a b l e f o r a l g a l s e t t l e m e n t . Such a p a t t e r n h e l p s e x p l a i n t h e d i s t r i b u t i o n o f a l g a e a t Squamish, w i t h many growing on s u r f a c e s r e l a t i v e l y rough i n t e x t u r e . S u b s t r a t e s p e c i f i c i t y may a l s o be a r e f l e c t i o n o f a c h e m i c a l l e a c h i n g from t h e s u r f a c e , e i t h e r s t i m u l a t i n g o r i n h i b i t i n g growth o f an a l g a ( e . g . Enteromorpha minima on wood). T h e o r e t i c a l p a t t e r n s o f d i s t r i b u t i o n and ecosystem s t r u c t u r e based s o l e l y on s u b s t r a t e p r e f e r e n c e do not'-c o i n c i d e w i t h o b s e r v e d p a t t e r n s on t h e Squamish d e l t a . M o d i f y i n g t h i s i s t h e problem o f h a b i t a t p r e f e r e n c e . F o r example, P y l a i e l l a l i t t o r a l i s was e p i p h y t i c on Carex lyngbyei a t t h e p e r i p h e r y o f t h e d e l t a but not i n t h e c e n t r a l p o r t i o n s . E. minima was found on wood s u r f a c e s o n l y i n t h e lo w e r i n t e r t i d a l and Mono stroma oxyspermum was l o c a t e d I n t i d e p o o l s o n l y I n t h e upper i n t e r t i d a l . F a c t o r s i n c l u d i n g s a l i n i t y - o s m o r e g u l a t i o n , 8 2 t e m p e r a t u r e , l i g h t i n t e n s i t y and q u a l i t y , d e s i c c a t i o n and c o m p e t i t i o n o p e r a t e a t Squamish t o produce o b s e r v e d ecosystem s t r u c t u r e . I n t e r s p e c i f i c c o m p e t i t i o n , c h e m i c a l and p h y s i c a l , i s an i m p o r t a n t f a c t o r r e g u l a t i n g s t r u c t u r e o f t h e a u t o t r o p h i c components at Squamish. The most d r a m a t i c , s i g n i f i c a n t example i s seen w i t h r e s p e c t t o Carex l y n g b y e i , t h e dominant v a s c u l a r p l a n t on t h e d e l t a . As v e g e t a t i o n h e i g h t i n c r e a s e s , t h e amount o f l i g h t r e a c h -i n g t h e sediment i s d r a s t i c a l l y r e d u c e d ( T a b l e 2). T h i s r e d u c t i o n r e s u l t s I n two t h i n g s . F i r s t , an en-hancement o f d i s t r i b u t i o n a nd,along w i t h i t , p r o d u c t I o n f o r s p e c i e s o f a l g a e w i t h low l i g h t p r e f e r e n c e ( T a b l e 2 0 ) . Second, i n s p e c i e s r e q u i r i n g more l i g h t f o r optimum p h o t o s y n t h e s i s , t h e r e s u l t I s 'reduced p r o d u c t i o n , r e s -t r i c t e d d i s t r i b u t i o n t o a r e a s o f l i g h t p e n e t r a t i o n ( p o o l s , open a r e a s ) and s u i t a b l e s u b s t r a t e . Complete removal o f t h e s p e c i e s c o u l d o c c u r when l i g h t f a l l s below th e c r i t i c a l l e v e l . Data on p r i m a r y p r o d u c t i o n (Appendix V I I I ) , d i s t r i b u t i o n (Appendix V I I ) and biomass (Appendices V I , V I I ) i n d i c a t e s u p p r e s s i o n o f a l g a l c o l o n i z a t i o n and growth I s i n p a r t c o n t r o l l e d by t h e p r e s e n c e o f v a s c u l a r p l a n t s . I n c r e a s e d c o l o n i z a t i o n and d i s t r i b u t i o n i s seen o n l y as a r e s u l t o f Carex a c t i n g as a s u b s t r a t e f o r P y l a i e l l a l i t t o r a l i s and A s s o c i a t i o n G, b o t h o f w h i c h f a v o r low l i g h t . The i n c r e a s e i s s i g n i f i c a n t f o r p r o d u c t i o n and energy f l o w as w i l l be d i s c u s s e d . 83 I n a d d i t i o n t o a c o m p e t i t i v e r e s ponse between v a s c u l a r p l a n t s and b e n t h i c a l g a e , t h e r e i s c o m p e t i t i o n between s p e c i e s o f macroalgae and/or m i c r o a l g a l a s s o -c i a t i o n s . Very l i m i t e d growth o f Enteromorpha minima o c c u r s mixed i n w i t h l a r g e s t a n d s o f Fucus on t h e p r e f e r r e d s u b s t r a t e o f b o t h (wood). W i t h i n a m e t e r , t h e r e a r e l u x u r i a n t s t a n d s o f E. minima under t h e same c o n d i t i o n s o f s u b s t r a t e , s a l i n i t y , l i g h t and t e m p e r a t u r e . Fucus, e i t h e r by i t s e x t e n s i v e , r o b u s t growth form w h i c h r e s u l t s i n s h a d i n g , o r by means o f a l a r g e amount o f o r g a n i c exudate ( S i e b u r t h 1969), e x c l u d e s E. minima. Hruby (1976) w o r k i n g w i t h iiamiWarfta s p . and Iridea s p . , notes a s i m l l i a r s i t u a t i o n i n w h i c h t h e z o n a t i o n l i n e between t h e two v a r i e s , dependent upon growth o f t h e l a r g e r s p e c i e s . L i g h t r e d u c t i o n i s s u g g e s t e d as s i g -n i f i c a n t i n i n t e r - s p e c i e s c o m p e t i t i o n , l e n d i n g s u p p o r t t o f i n d i n g s o f t h e c u r r e n t s t u d y . C o m p e t i t i o n o f a c h e m i c a l n a t u r e may a l s o be a c t i v e i n d e t e r m i n i n g a l g a l d i s t r i b u t i o n and p r o d u c t -Io n p a t t e r n s . The p o s s i b l e e f f e c t o f e x u d a t i o n from Fucus has been mentioned but no s u p p o r t i v e d a t a are known. However, B e r g l u n d (1969) mentions a s u b s t a n c e exuded by Enteromorpha s p . , which g r e a t l y s t i m u l a t e s I t s own growth but not t h a t o f o t h e r s p e c i e s . T h i s c o u l d e x p l a i n t h e l a r g e u n i a l g a l growths o f E. minima and E. prolifera o b s e r v e d a t Squamish. Once t h e a l g a becomes e s t a b l i s h e d i n t h e absence o f a dominant l i g h t 84 reducing species, i t could grow undisturbed by competitors. Converse to t h i s , exudation of growth antagonists or i n h i b i t o r s Is noted for other marine algae and could contribute to the formation of unialgal patches (Conover and Sieburth 1964, Sieburth 1968, Russel and F i e l d i n g 1974, Fletcher 1975). Growth stim-ulators may also e x i s t . Much work remains to be done i n t h i s area but since a t i d a l marsh environment i s under stress, a condition favoring release of exudates, these may be important i n c o n t r o l l i n g ecosystem structure. Light, i n view of i t s significance for photosyn-t h e s i s , i s an obvious factor c o n t r o l l i n g d i s t r i b u t i o n and primary production. In the presence of a suitable substrate, the lower l i m i t of growth for an alga at Squamish i s primarily under the influence of reduced l i g h t Intensity and changed spectral quality experienced with depth. The often turbid nature of estuaries, especially the fjord-type t y p i f i e d by Squamish, increase the attenuation rate rapidly (Fig. 4) and results i n a compression of v e r t i c a l zonation with depth i n a r e l a t i v e -ly short distance (Druehl 1967). The appearance at Squamish of brown algae higher up on the shore r e l a t i v e to other coastal i n t e r t i d a l habitats i s suggestive of th i s compression. In a d d i t i o n s t o l i g h t , s a l i n i t y may affect the lower l i m i t of d i s t r i b u t i o n during freshet .. when strong low s a l i n i t y lens i s present. The re s u l t would be loss of species with low osmoregulatory capabil-i t i e s . 85 The upper l i m i t of an alga i s variable and con-t r o l l e d by several factors. High l i g h t i n t e n s i t y , known to be damaging to attached marine algae (Hellebust 197^) may be a l i m i t a t i o n to species normally found In the lower i n t e r t i d a l region which, due to v e r t i c a l compression, experience longer periods of high l i g h t on exposure. Being less well adapted, they cannot survive even i f able to colonize. Chlorophytes common to the upper i n t e r t i d a l seem better adapted to tolerate increased l i g h t (Blebl 1951), often having higher optimal l i g h t requirements for net photosynthesis (Mathieson and Burns 1971). This i s r e f l e c t e d In the wide d i s t r i b u t i o n of Monostroma oxyspermum, Ehizoolonium implexum, Cladophora sp. and Spirogyra sp. on the upper regions of the delta. Primary production of these species i s p o s i t i v e l y correlated with l i g h t i n t e n s i t y (Table 20). Rapid l i g h t attenuation on immersion during the high runoff period of summer r e s t r i c t s algae to a higher position i n the i n t e r t i d a l where a l l but the most l i g h t tolerant are selected against on emersion. The Increased l i g h t regime and v e r t i c a l compression selects for algae of the upper i n t e r t i d a l . This i s evident comparing species composi-t i o n between the study area and the extreme eastern part of the estuary where effects of r i v e r freshet are l e a s t , r e s u l t i n g In low l i g h t attenuation and reduced v e r t i c a l compression. The lower l i m i t of growth for a 86 g i v e n a l g a appears g r e a t e r i n the r e g i o n of reduced l i g h t a t t e n u a t i o n . S e v e r a l brown algae are abundant wit h a concommitant decrease i n chlorophyte d i v e r s i t y . S i m i l a r s e a s o n a l s a l i n i t y p a t t e r n s f o r t h i s e a s t e r n r e g i o n and the study area (Levlngs e§ al. 1976) reduce tne p o s s i b i l i t y o f s a l i n i t y i n f l u e n c i n g s p e c i e s d i s t r i -b u t i o n between the two r e g i o n s . Accompanying i n c r e a s e d summer l i g h t i n t e n s i t i e s are c o n d i t i o n s o f Increased temperature to which an a l g a must a l s o adapt ( i . e . e u r y t h e r m a l ) . In determining the e f f e c t s o f temperature on d i s t r i b u t i o n and produc-t i o n , c o n s i d e r a t i o n must be g i v e n to emersion and immersion temperatures. Water temperatures remain moderate over a t i d a l c y c l e throughout the year ( P i g . 6) and s t a t i s t i c a l analyses snow t h i s change s i g n i f i c a n t i n l i m i t i n g p r o d u c t i o n of algae t o l e r a n t o f h i g h temp-e r a t u r e and d e s i c c a t i o n (Table 10, 20). However, an even g r e a t e r i n f l u e n c e e x e r t e d by temperature i s the extremes o f water to a i r temperature on emersion ( F i g . 6). Aigae experience daytime emersion d u r i n g summer and n i g h t - t i m e d u r i n g the w i n t e r , exposing them to great temperature extremes tnrougnout. S p a t i a l - t e m p o r a l d i s -t r i b u t i o n and p r o d u c t i o n p a t t e r n s are e x p l a i n e d p a r t i a l l y by the degree to which a s p e c i e s i s eurythermal. S t u d i e s by Healey (1972), Yokohama (1972), and Mathieson and N o r a l l (1975) suggest an adaptive s h i f t i n the pro-duction-temperature r e l a t i o n s f o r s e v e r a l algae present 87 t h r o u g h o u t t h e y e a r , w i t h l o w e r o p t i m a l t e m p e r a t u r e s f o r n e t p r o d u c t i o n i n w i n t e r compared t o summer. Al g a e p r e s e n t f o r a p a r t o f t h e y e a r may have a l i m i t e d t o l e r -ance t o te m p e r a t u r e changes. D u r a t i o n o f exposure t o a h i g h e r o r lo w e r t e m p e r a t u r e r a t h e r t h a n t h e amount o f change may be I m p o r t a n t , as exposure time i n c r e a s e s w i t h h e i g h t i n t h e i n t e r t i d a l . R e s i s t a n c e t o d e s i c c a t i o n shown by an a l g a i s an o t h e r f a c t o r d e t e r m i n i n g t h e s t r u c t u r e o f t h e b e n t h i c a l g a l community a t Squamish. Emersion-immersion time and d u r a t i o n , a i r t e m p e r a t u r e and d r y i n g e f f e c t s o f w i n d s , f r e q u e n t d u r i n g t h e summer, a l l a f f e c t r a t e o f d e s i c c a t i o n . A l g a e such as Cladophora s p . , Monostroma oxyspermum and Spirogyra sp. have l i t t l e apparent r e s i s -t a n c e , b e i n g r e s t r i c t e d t o t i d e p o o l s on emersion. Others such as Enteromorpha minima, E. prolifera and P y l a i e l l a l i t t o r a l i s w i t h s t a n d d e s i c c a t i o n v e r y w e l l . I n t e r m e d i a t e between t h e s e two groups a r e dia t o m domin-a t e d a s s o c i a t i o n s r e q u i r i n g some m o i s t u r e , e i t h e r i n t h e form o f g r a d u a l r u n o f f o r t i d e p o o l s . D e s i c c a t i o n f o r a p o r t i o n o f t h e time appears t o be o f b e n e f i t t o some a l g a e . Johnson et al. (1974) and B r i n k h u i s et al. (1976) r e p o r t t h a t f o r i n t e r t i d a l s p e c i e s t e s t e d , e s p e c i a l l y t h o s e i n t h e mid-upper r e g i o n s , p r o d u c t i o n on emersion o f t e n exceeds t h a t on immersion by 1.6 - 6.6 t i m e s . S p e c i e s from t h e l o w e r i n t e r t i d a l have e q u a l o r l o w e r emersion p r o d u c t i o n r a t e s compared 88 t o i m m e r s i o n , b e i n g a d v e r s e l y a f f e c t e d by i n c r e a s e d l i g h t and d e s i c c a t i o n (Brown and Johnson 1964, Imada et a l . 1970). Enteromorpha, a l o n g w i t h o t h e r h i g h LTD t o l e r a n t c h l p r o p h y t e s ( T a b l e 10), may have th e c a p a c i t y f o r g r e a t e r emersion p r o d u c t i o n . S i m i l a r l y , s p e c i e s f a v o r i n g low l i g h t , such as P y l a i e l l a l i t t o r a l i s ( T a b l e 10), may b e n e f i t from emersion d u r i n g t h e w i n t e r when l i g h t i s r e d u c e d . Thus, i t i s s u g g e s t e d t h a t d e s i c c a t i o n may a f f e c t b e n t h i c a l g a l d i s t r i b u t i o n and p r o d u c t i o n i n a n e g a t i v e o r p o s i t i v e f a s h i o n , depending upon s p e c i e s , l o c a t i o n i n t h e I n t e r t i d a l and season. V e r t i c a l c o m p r e s s i o n r e s u l t s i n a s e l e c t i o n f o r mid-upper i n t e r t i d a l h i g h l i g h t t o l e r a n t s p e c i e s i n t h e summer. I n c r e a s e d p r o d u c t i o n on d e s i c c a t i o n may l e a d t o maximum b e n t h i c a l g a l p r o d u c t i o n i n an e s t u a r y . E u r y h a l i n i t y ( o s m o r e g u l a t o r y c a p a b i l i t y ) , i n a d d i t i o n t o g o v e r n i n g t h e e n t r y o f an a l g a i n t o an a r e a can a l s o a c t as a c o n t r o l l i n g f a c t o r I n s e a s o n a l and s p a t i a l p a t t e r n s o f d i s t r i b u t i o n and p r o d u c t i o n . The w a t e r column over t h e d e l t a remains r e l a t i v e l y homogen-ous over a t i d a l c y c l e (+ 3°/oo) f o r most o f t h e y e a r . The m a j o r i t y o f wide and r a p i d s a l i n i t y changes o c c u r on exposure t o e i t h e r c o n d i t i o n s o f r a i n , e v a p o r a t i o n i n s h a l l o w t i d a l p o o l s o r d e s i c c a t i o n . C e r t a i n s p e c i e s show t h i s l i m i t a t i o n c l e a r l y , w i t h S p i r o g y r a sp. t h e most n o t a b l e . I t s p r e s ence i n t i d a l p o o l s i s n e g a t i v e l y c o r r e l a t e d w i t h s a l i n i t y ( T a b l e 20), d i s a p p e a r i n g on 89 i n c r e a s e d s a l i n i t y a f t e r f r e s h e t . Cladophora sp. shows the same seasonal p a t t e r n s but appears l e s s s e n s i t i v e to s a l i n i t y ( s l i g h t l y more e u r y h a l i n e ) . Van der Werff (i960) suggests t h a t s a l i n i t y governs the d i s t r i b u t i o n and p r o d u c t i o n of b e n t h i c diatoms In e s t u a r i e s . However, more r e c e n t l y W i l l i a m s (1964) and Admlraal (1977) have p r o v i d e d c o n t r a d i c t o r y data. Admiraal s t a t e s t h a t b e n t h i c diatoms a c t u a l l y have a very h i g h t o l e r a n c e to s a l i n i t y change, showing a drop i n net p r o d u c t i o n o f only 30% going from 4 to 60 °/oo s a l i n i t y . T h i s supports data from Squamish showing the h i g h s a l i n i t y t o l e r a n c e of e s t u a r i n e b e n t h i c diatoms (Table 6, Appendix V I I I ) . S a l i n i t y does appear to a f f e c t the s p e c i e s d i v e r s i t y o f an a s s o c i a t i o n , w i t h lower s a l i n i t y p roducing g r e a t e r d i v e r s i t y . S u l l i v a n (1977) r e p o r t s a s i m i l a r s i t u a t i o n f o r edaphic (b e n t h i c ) diatom a s s o c i a t i o n s i n New J e r s e y s a l t marshes. Inoorder to p e r s i s t over an extended p e r i o d , an a l g a must be able to adapt to r a p i d changes as w e l l as to c o n t i n u a l l y i n c r e a s i n g and d e c r e a s i n g s a l i n i t y o f the surrounding waters. Algae c o l o n i z i n g the d e l t a can be c l a s s i f i e d i n t o two groups based on s a l i n i t y . Some can t o l e r a t e s a l i n i t y ranges (0 - 30 °/oo — s t r o n g l y eury-h a l i n e ) whereas others are more r e s t r i c t e d , ( e i t h e r 0 -15 or 15 - 30 °/oo — w e a k l y e u r y h a l i n e ) . The m a j o r i t y o f macroalgae and m l c r o a l g a l j . a s s o c i a t i o n s are s t r o n g l y e u r y h a l i n e . Thus, w i t h the exceptions o f Spivogyva sp. 90 and Cladophora sp., s a l i n i t y does not appear to be a major f a c t o r c o n t r o l l i n g d i s t r i b u t i o n and p r o d u c t i o n o f algae on the p o r t i o n of the Squamish d e l t a s t u d i e d . In c o n t r a s t to the complex i n t e r a c t i o n s o f f a c t o r s c o n t r o l l i n g s t r u c t u r e o f the b e n t h i c a l g a l community, i s the apparent s i m p l i c i t y o f f a c t o r s f o r the v a s c u l a r p l a n t s . Macrovegetation on the Squamish d e l t a , dominated by Carex lyngbyei , has been i n v e s t i g a t e d by Lim and Levings U973) and Levings and Moody (.1976). Zonatlon from low to h i g h i n t e r t i d a l o f low sedge to h i g h sedge to grasses and c l o v e r was noted. T h i s i s c o n s i d e r e d a response to t o t a l Immersion, l i g h t a v a i l a b i l i t y , and s a l i n i t y . Since C. lyngbyei o r i g i n a t e d i n a freshwater h a b i t a t (Stebbins 1950), low s a l i n i t y concurrent with i t s growth p e r i o d and the l a c k of s u b s t r a t e - h a b i t a t p r e f e r e n c e are viewed as major f a c t o r s p e r m i t t i n g entry and establishment over v i r t u a l l y the e n t i r e d e l t a s u r -f a c e . High l i g h t i n t e n s i t y and daytime emersion f a v o r growth of emergent v e g e t a t i o n . Rapid growth and the dense nature o f C. lyngbyei remove the low l i g h t s p e c i e s through l i g h t l i m i t a t i o n , as was the case f o r b e n t h i c algae. C. lyngbyei i s w e l l adapted to e x i s t e n c e on a t i d a l marsh such as Squamish and e x e r t s a s t r o n g i n f l u e n c e on ecosystem s t r u c t u r e and f u n c t i o n , as w i l l be d i s c u s s e d . In summary, s t r u c t u r e o f the a u t o t r o p h i c component o f the t i d a l marsh ecosystem at Squamish can be d e s c r i b e d 91 i n terms o f s p e c i e s c o m p o s i t i o n , s p a t i a l arrangements, d i s p e r s i o n s and abundance. S p e c i e s c o m p o s i t i o n i s i n i t i a l l y governed by o s m o r e g u l a t o r y c a p a b i l i t i e s o f an a l g a . S p e c i e s s u c c e s s i o n t h r o u g h o u t t h e y e a r i s seen as p r i m a r i l y a response t o l i g h t i n t e n s i t y , w i t h sedge growth h a v i n g a s t r o n g I n f l u e n c e . D e s i c c a t i o n , w i t h t h e c o n c o m i t a n t e f f e c t s o f t e m p e r a t u r e and s a l i n i t y , i s a l s o c o n s i d e r e d a s i g n i f i c a n t f a c t o r . S p a t i a l arrangement and d i s p e r s i o n a r e c o n t r o l l e d by s u b s t r a t e -h a b i t a t p r e f e r e n c e and degree o f h a b i t a t s p e c i f i c i t y . P r o d u c e r s showing s t r o n g s p e c i f i c i t y t e n d t o be ag g r e g a t e d ( e . g . S p i r o g y r a s p . , A s s o c i a t i o n B ) , whereas t h o s e w i t h weaker s p e c i f i c i t y appear randomly d i s t r i b -u t e d ( e . g . A s s o c i a t i o n s E and G, Monostroma oxyspermum), I n t e r s p e c i f i c c o m p e t i t i o n i s y e t a n o t h e r f a c t o r a f f e c t -i n g s p a t i a l arrangement. The abundance o f each p r i m a r y p r o d u c e r i s an i m p o r t a n t a s p e c t o f ecosystem s t r u c t u r e , o r g a n i z a t i o n , and f u n c t i o n . Measured as s t a n d i n g c rop b i o m a s s , abundance r e f l e c t s t h e amount o f p r e f e r r e d s u b s t r a t e -h a b i t a t a v a i l a b l e , t h e a d a p t a b i l i t y o f t h e p r o d u c e r t o th e environment ( I . e . net p r o d u c t i v i t y ) and t h e growth form ( m i c r o - vs m a c r o a l g a e ) . Car ex l y n g b y e i i s ;the major c o n t r i b u t o r o f biomass. A s s o c i a t i o n s G and E and P y l a i e l l a l i t t o r a l i s are next h i g h e s t i n abundance (Appendix V I ) . The v a l u e o f abundant p r e f e r r e d s u b s t r a t e and t h e c h a r a c t e r o f weak h a b i t a t s p e c i f i c i t y a r e 92 r e a s o n s f o r t h e i r dominance, s i n c e a l l have wide d i s t r i b u t i o n ( F i g . 10). On a square meter b a s i s , A s s o c i a t i o n s E and G have t h e l o w e s t biomass on t h e d e l t a ( T a b l e 7). I I . Ecosystem F u n c t i o n S t r u c t u r a l a n a l y s i s o f an ecosystem I s o f l i m i t e d v a l u e i n u n d e r s t a n d i n g ecosystem o p e r a t i o n . I t i s an i n d i c a t i o n o f what I s p r e s e n t , how i t I s d i s t r i b u t e d , and an e s t i m a t e o f t h e amount p r e s e n t . P o s s i b l e f a c t o r s c o n t r o l l i n g s t r u c t u r e may a l s o be d e r i v e d , as done i n t h i s t h e s i s . Comparisons o f d i f f e r e n t e c o s y s -tems a r e p o s s i b l e u s i n g such d a t a . However, n e i t h e r t h e f u n c t i o n i n o r i m p o r t a n c e o f a p a r t i c u l a r component t o t h e ecosystem nor o p e r a t i o n o f t h e ecosystem as a u n i t are r e v e a l e d . Ecosystem p r o c e s s e s and i n t e r r e l a t i o n s ( f u n c t i o n s ) a r e best d e s c r i b e d i n terms o f energy r a t h e r t h a n s t r a i g h t o r g a n i c m a t t e r ( L l e t h 1968). Energy p r o v i d e s a more c o m p a r a t i v e b a s i s , removing v a r i a t i o n s i n o r g a n i c and c a r b o n c o n t e n t o f d i f f e r e n t o r g a n i s m s . The s t u d y o f e c o l o g i c a l e n e r g e t i c s (energy f l o w ) d e a l s w i t h t h e i n p u t o f energy ( p r i m a r i l y s o l a r ) and t h e pathways and e f f i c i e n c i e s w i t h which i t I s c o n v e r t e d by a u t o t r o p h s ( p r i m a r y p r o d u c e r s ) and u t i l i z e d by h e t e r o t r o p h s (decom-p o s e r s and consumers). The magnitude and e f f i c i e n c y o f s o l a r energy c o n v e r s i o n , i t s manner o f s t o r a g e as 93 c h e m i c a l energy and subsequent u t i l i z a t i o n a r e c h a r a c t e r i s t i c o f a p a r t i c u l a r ecosystem ( I . e . g i v e i t f u n c t i o n a l i d e n t i t y ) . However, even though t h e a u t o t r o p h i c and h e t e r o t r o p h i c components may d i f f e r , t h e i n i t i a l pathways o f energy t r a n s f e r a re b a s i c a l l y v t h e same and can be p r e s e n t e d as a u n i v e r s a l energy f l o w model. Energy s t o r a g e Energy c o n v e r s i o n (Net p r o d u c t i o n ) D i s s o l v e d P a r t i c u l a t e The f l o w p a t t e r n may r e p r e s e n t two approaches t o the s t u d y o f e n e r g e t i c s . By r e p r e s e n t i n g a s i n g l e p r o -d u c e r , such as Enteromorpha minima, an emphasis i s p l a c e d on f o o d c h a i n o r p o p u l a t i o n a n a l y s i s . The importance and use o f each p r o d u c e r i s d e t e r m i n e d and compared w i t h t h a t o f o t h e r s . T h i s r e s u l t s i n s p e c i f i c i n f o r m a -t i o n on mechanisms i n f l u e n c i n g energy f l o w . Examining energy f l o w on ancommunlty ( v a s c u l a r p l a n t o r b e n t h i c a l g a l ) o r ecosystem b a s i s p r o v i d e s f o r a b r o a d e r v i e w . Having d e t e r m i n e d s p e c i f i c and g e n e r a l pathways, l t i s p o s s i b l e t o p r e d i c t t h e s o u r c e s and e f f e c t s o f energy 94 l o s s from an ecosystem and p o t e n t i a l consequences o f s t r u c t u r a l a l t e r a t i o n . Energy f l o w r e p o r t e d over a y e a r p r o v i d e s a w e l l d e f i n e d measure. Most communities and s p e c i e s have n a t u r a l p e r i o d i c i t i e s r e l a t e d t o changing p h y s i c a l -c h e m i c a l f a c t o r s , making a measurement over t h i s t ime p e r i o d d e s i r a b l e and t h e common p r a c t i c e I n e s t a b l i s h -i n g energy pathways. W i t h i n t h e l o n g term v a r i a t i o n , s h o r t term o r s e a s o n a l p a t t e r n s e x i s t , i n which s i g n i f -i c a n t p r o d u c e r s change. D e t e r m i n a t i o n o f t h i s i s v a l u a b l e . A p r o d u c e r may be a p r e f e r r e d f o o d s o u r c e f o r a p a r t i c u l a r consumer i n a d d i t i o n t o c o n t r i b u t i n g t o t h e g e n e r a l energy p o o l o f t h e ecosystem. B r i n k h u l s (1976a, b) notes the v a l u e o f measurements over t h e e n t i r e y e a r f o r p e r s i s t e n t s p e c i e s and over t h e growth p e r i o d f o r s e a s o n a l s p e c i e s i n d e t e r m i n i n g t h e f u n c t i o n o f a s p e c i e s w i t h i n an ecosystem. Data from th e f i r s t f o u r months r e a s e a r c h are not i n c l u d e d i n f o r m u l a t i o n o f energy pathways. T h i s a l l o w s f o r a p e r i o d o f methodology development and improvement. Thus, th e one y e a r p e r i o d from September 1974 t h r o u g h August 1975 i s s e l e c t e d . The s t u d y o f energy f l o w i s i n I t s i n f a n c y compared t o o t h e r a r e a s o f e c o l o g y and i s u n f o r t u n a t e l y based on numerous as s u m p t i o n s . U n l e s s a l l energy s o u r c e s , methods and r a t e s o f s t o r a g e , c o n v e r s i o n , i n p u t , u t i l -i z a t i o n and l o s s e s f o r e i t h e r a s i n g l e p r o d u c e r o r t h e 95 ecosystem as a unit can be determined independently, many assumptions and estimates must be made i n deriving energy pathways. Ecosystem structure provides some information with respect to these areas, as w i l l be discussed. A. Energy sources, conversion, input and storage. Energy sources. Three energy sources exist at Squamish. The f i r s t , and that common to other ecosys-tems, i s radiant energy. Two basic components of the rad i a t i o n energy environment, solar and longwave thermal radiatio n f l u x , are Important. To consider one i n the absence of the other provides only a p a r t i a l understand-ing of t o t a l r a d i a t i o n change at the earth's surface. However, Odum $1971) points out that even though the " t o t a l r a d i a t i o n flux determines the 'conditions of existence' to which an organ!smsmust adapt, i t i s the integrated solar radiation...which i s of greatest i n t e r -est i n terms of productivity and nutrient cycling within the ecosystem." Solar radia t i o n reaches the biosphere at a constant -2 -1 rate of 2 g cal*cm -min , becoming attenuated exponen-t i a l l y due to scattering and absorption by cloud cover and water vapor i n the atmosphere (Odum 1971). At most, 67% may reach sea l e v e l on a clear summer day, with attenuation occurring to varying degrees as a function of wavelength and frequency (Gates 1965). Reifsnyder and L u l l (1965) estimate that on a clear day sea l e v e l 96 radiati o n i s composed of oa. 10% u l t r a v i o l e t (<400 nm), 455? v i s i b l e (400-700 nm), and 1*5% infrared (>700 nm). However, under conditions of dense cloud cover, dust and vapor, further attenuation and a l t e r a t i o n of spectral d i s t r i b u t i o n occurs permitting primarily v i s i b l e r a d i -ation to pass through the atmosphere. Attenuation becomes especially s i g n i f i c a n t at Squamish where cloud cover and i n d u s t r i a l haze are common. V i s i b l e r a d i a t i o n (photosynthetically available radiation—PAR) i s that portion of t o t a l solar r a d i a t i o n actually available to and usable by primary producers. P h i l l i p s o n (1966) estimates annual PAR Input for areas at decreasing latitudes with B r i t a i n .{oa. 55° N) receiv-ing 2.5 x 10 5 kcal'm" 2, Michigan (oa. 44° N) 4.7 x 10 5 o 'S —2 and Georgia (oa. 32 N) 6.0 x 10^ kcal'm . Reifsnyder and L u l l (1965) give a t h e o r e t i c a l maximum annual PAR for the northwestern United States (ca.k$l° N) of 6.95 •5 -2 x 10"^  kcal«m , assuming a horizontal surface. Estimated 5 —2 annual PAR input for Squamish of 4.15 x 10^ kcal'm" '{Table 1) f a l l s well below th i s and s l i g h t l y below that for Michigan. The discrepancy from the t h e o r e t i c a l PAR can be attributed to steep mountains surrounding Squamish and to the frequent presence of an i n d u s t r i a l haze layer. Both tend to decrease in t e n s i t y and duration of rad i a -t i o n . Solar radiat i o n represents the single most important source of energy to an ecosystem. A second source of energy for producers on the Squamish delta i s that of t i d a l action. The mean t i d a l 97 a m p l i t u d e o f ca. 4 m, supplemented by c u r r e n t and w i n d s , p r o v i d e s a c o n s i d e r a b l e energy s u b s i d y . T h i s tends t o reduce t h e c o s t o f i n t e r n a l s e l f - m a i n t e n a n c e o f p r i m a r y p r o d u c e r s , m a x i m i z i n g t h e energy g o i n g i n t o p r o d u c t i o n ( s t o r a g e ) and m i n i m i z i n g t h a t t o r e s p i r a t i o n . The p r i n c i p l e o f an e s t u a r y as an energy s u b s i d i z e d system has been w e l l documented (Odum 1971, Odum and Banning 1973, N i x o n and O v i a t t 1973} Odum 1974, S t e e v e r et al. 1976) and t h e b e n e f i t s a re c l e a r . However, p a s t a c e r t a i n t i d a l a m p l i t u d e , d i f f e r i n g between syste m s , p h y s i c a l s t r e s s ( m e c h a n i c a l damage) outweighs t h e b e n e f i t s . T h i s n e g a t i v e e f f e c t I s not e v i d e n t a t Squam-i s h , as su g g e s t e d by h i g h p r o d u c t i o n o f v a s c u l a r p l a n t s d u r i n g t h e summer and a l g a l e p i p h y t e s d u r i n g t h e w i n t e r . Maintenance o f p o s i t i v e p r o d u c t i o n o v e r t h e d e l t a t h r o u g h o u t t h e y e a r does not i n d i c a t e e x c e s s i v e t i d a l f l u c t u a t i o n . A A t h i r d s o u r c e o f energy a f f e c t i n g t h e Squamish d e l t a i s a d d i t i o n ( i m p o r t ) o f p a r t i c u l a t e and d i s s o l v e d o r g a n i c m a t t e r . T h i s o r i g i n a t e s from Howe Sound ( p l a n k -t o n ) , t h e landward p o r t i o n o f t h e C e n t r a l B a s i n ( b e n t h i c a l g a e , d e t r i t u s ) and from Fucus beds seaward o f t h e stud y a r e a . Energy f r o m . a d d i t i o n i s u n l i k e t h e p r e v i o u s two s o u r c e s i n t h a t i t does not r e q u i r e c o n v e r s i o n , b e i n g i m m e d i a t e l y a v a i l a b l e t o consumers. A l o n g w i t h t i d a l e n e r g y , i t a c t s as a bonus t o t h e d e l t a ecosystem, enhancing a v a i l a b l e energy i n t h e p r i m a r y t r o p h i c l e v e l . 98 A l t h o u g h added o r g a n i c s account f o r o n l y oa. 5% o f t o t a l a v a i l a b l e e n e r g y , t h e i r p r e s e n c e i s c o n s i d e r e d s i g n i f i c a n t t o t h e system, a c t i n g as a s u b s t r a t e f o r h e t e r o t r o p h i c u p t a k e , growth s t i m u l a t o r s and/or i n h i b -i t o r s and as food f o r g r a z i n g and d e t r i t a l o r g a n i s m s . Energy c o n v e r s i o n , i n p u t and s t o r a g e . Enerjgy e n t e r s t h e Squamish ecosystem p r i m a r i l y by p h o t o s y n -t h e t i c c o n v e r s i o n ( I . e . g r o s s p r i m a r y p r o d u c t i o n ) . 1) V a s c u l a r p l a n t s . Caress l y n g b y e i , w h i c h o c c u p i e s oa. 80$ o f t h e I n t e r t i d a l m arshland a t Squamish, i s t h e major s i t e o f energy c o n v e r s i o n and s t o r a g e on t h e d e l t a . Due t o i t s dominance, a d i s c u s s i o n o f energy f l o w t h r o u g h Carex l y n g b y e i i s assumed t o r e p r e s e n t t h a t f o r the v a s c u l a r p l a n t community on t h e d e l t a . L e v l n g s and Moody (1976) p r e s e n t growth and biomass d a t a upon wh i c h p r o d u c t i o n and energy f l o w a r e based I n t h i s t h e s i s . I n e a r l y March t h e t i d a l marsh i s a f l a t mat o f d e c a y i n g v e g e t a t i o n r e m a i n i n g from t h e p r e v i o u s y e a r ( F i g . 13), w i t h some,new shoots becoming a p p a r e n t . The d e c a y i n g mat d i s a p p e a r s by May and i n mid June d i e - b a c k o f f r e s h growth becomes apparent ( E e v i n g s and Moody 1976). Maximum growth i s re a c h e d i n J u l y ( F i g . 13) and minimum i n August a t t h e end o f t h e growing season (Appendix X I ) . D e c o m p o s i t i o n proceeds o v e r w i n t e r and I n t o s p r i n g and summer o f t h e f o l l o w i n g y e a r . Net p r o d u c t i o n (above and below ground) was e s t i m -— 2 -1 a t e d t o be oa. 2067 g organic«m -season (Appendix X I ) . 99 F i g u r e 13. Cares: lyngbyei meadow i n e a r l y March, showing mat o f decayed v e g e t a t i o n , and i n l a t e J u l y at the time o f maximum growth. 99a 100 Assuming organic matter to be 50% C, t o t a l net primary — 2 —1 production amounts to about 1034 g C«m *yr . This value l i k e l y represents an underestimate. Basing net production on standing crop biomass often f a i l s to account f o r turnover of l i v e material between sampling periods (Kirby and Gosselink 1976, Turner 1976). Unmeasured herbivory, tissue decay and erosion, exudation, t i d a l amplitude (energy subsidy), current action and winds, along with f a v o r a b i l i t y of the growing season a l l a ffect turnover rate (Vollenweider 1974)'. Turnover rate appears faster In high energy, subsidized environ-ments such as t i d a l marshes. Hatcher and Mann (1975) estimate an average loss of 28.5% of end of year stand-ing biomass f o r s a l t marshes. Nixon and Oviatt (1973) indicate a loss of 10 - 15% for s i m i l a r marshes. Thus, assuming loss of above ground organic matter to be a minimum of 10%, a t o t a l production estimate of 2177 -2 -1 g organic.m *yr i s arrived at, based on above and below ground estimates. Caloric content determined for Carex lyngbyei (4.08 kcal'g organic"^) compares favorably with values reported by Straskraba (1968) and Grabowske (1973) for other Carex species. Below ground energy content (I.e. rhizomes) was assumed to be the same as above ground (Dykyjova and P r i b i l 1975). Thus, energy available to the delta ecosystem as end of year standing crop of —2 —2 aa. 8880 kcal'm i s separated into 4707 kcal'm above 101 _2 ground and 4173 kcal m below ground. U t i l i z a t i o n i s e s s e n t i a l l y r e s t r i c t e d to the area of production. Assuming a r e s p i r a t i o n rate of 505? for Carex l y n g b y e i with i t s freshwater o r i g i n (Stebbins 1950), under brackish conditions, the above values must be doubled to obtain estimates of gross production. This -2 -1 amounts to oa. 97 kcal«m »day , approaching the upper _2 l i m i t of energy Input (100 kcal'm ) noted by Odum (1971). I f the r e s p i r a t i o n estimate were lowered to 30$( an average for macroalgal r e s p i r a t i o n ) , the delta would s t i l l rank high i n terms of energy input (oa. 67 kcal* -2 -1 m 'day ), i n d i c a t i n g i t s great productive capacity. Energy conversion by Carex l y n g b y e i i s very e f f i c i e n t . Average photosynthetic e f f i c i e n c y (net productipn/PAR) of 3.04/J calculated over the growing season i s high compared to most t e r r e s t r i a l systems at 1-3% (McNaughton and Wolf 1973). Peak photosynthetic e f f i c i e n c i e s of 4.95/2 i n June compare with the maximum of 5% noted by P h i l l i p s o n (1966). Abundant moisture, nutrients and the influence of t i d a l energy subsidy lead to e f f i c i e n t use of solar energy. The majority of energy conversion and storage carr-ied on by vascular plants remains as POM, with only a small f r a c t i o n leached as organic exudates (DOM) (Tukey 1970, Wetzel and Manny 1972, Turner 1974, Gallagher et ail. 1976). Assuming 3-45? of converted energy goes to DOM,??.and a c a l o r i c content equal to that for POM, an 102 — 2 —1 estimated 236 kcal«m «yr DOM i s exuded above ground during the growth period of Carex lyngbyei. Although t h i s represents a very low portion of production, i t i s s i g n i f i c a n t i n terms of the t o t a l amount added over the large growth area. 2) Benthic algae. Fourteen major benthic a l g a l species and/or associations with d i f f e r i n g seasonal patterns, productivity and ecology dominate the al g a l f l o r a of Squamish. The capacity of each for energy conversion and storage and t h e i r contribution to a v a i l -able energy on the delta,.attributable to benthic algae are discussed. To f a c i l i t a t e examination of energy flow through a square meter of each producer, energy conversion (gross production) i s separated into r e s p i r a t i o n and available stored energy (DOM,POM) F i g . 14). Monostroma oxyspermum and Pylaiella l i t t o r a l i s are the p o t e n t i a l l y most valuable species (Fig. 14). These are both low LTD forms with high production max-ima (Table 10). Two high LTD species, Enteromorpha minima and Spirogyra sp. (Table 10) also appear as major sources of energy input and storage 0 (Fig~. 14). The conclusion drawn Is that species, either persistent or seasonal, are present throughout the year with a high pot e n t i a l input of available energy. This i s based on high storage rate (net production) and reasonably high photosynthetic e f f i c i e n c i e s (Fig.14) and c a l o r i c content 103 F i g u r e 14. Energy Input (gross p r o d u c t i o n ) f o r each major producer separated Into d i s s o l v e d The numbers under each producer r e f e r to a v a i l a b l e PAR (kcal'm • y r x 10J) over the growth p e r i o d and to p h o t o s y n t h e t l c e f f i c i e n c y (%), r e s p e c t i v e l y . (Minor A s s o c i a t i o n s (SL and B not i n c l u d e d i n graph). kcal-nT 2.yr - 1 (x102) ro ro ro *» oo i«o o> o -i*. oo j t i i i_ -J I I J I L 3.15 0-19^ C l a d o p h o r a s p . 4.15 0.30 / 37 En t e r o m o r p h a m i n i m a 3.60 0 .22^1 E . p r o l i ( e ra 4.15 0.52% .Monos t r o m a o x y s p e r m urn 3.96 0.24^ R h i z o c l o n i u m i m p l e x u m 2.80 0 . 3 7 / Sp i rog y r a sp. 2.05 0.732 P y l a i e l l a l i t t o r a l i s 2.27 0.37^ A s s o c i a t i o n A 0.51 0 . 6 l / . A s s o c i a t i o n D 4.15 0 . 2 8 / A s s o c i a t i o n E 4.15 0.19/ . .Assoc ia t ion F 0.41 0.30/ 1 A s s o c i a t i o n G 2.64 3 . 0 4 ^ C a r e x l yngbye i B£0T CO CO CO o w o w 104 (T a b l e 16). The h i g h r a n k i n g o f A s s o c i a t i o n E, a p e r s i s t e n t diatom-dominated g r o u p i n g o f low prod u c -t i v i t y , i s p r i m a r i l y due t o t h e h i g h c a l o r i c c o n t e n t (aa. 1.5 t i m e s t h a t o f t h e n o t e d m a c r o a l g a e ) . The imp o r t a n c e o f b a s i n g ecosystem f u n c t i o n on energy r e l a t i o n s i s emphasized. The v e r y minor energy c o n t r i -p b u t i o n by a m o f A s s o c i a t i o n G s h o u l d be n o t e d a t t h i s p o i n t f o r f u t u r e r e f e r e n c e . Low p r o d u c t i v i t y ( T a b l e 10), biomass (energy s t o r a g e ) and c a l o r i c c o n t e n t ( T a b l e 016) d i c t a t e i t s apparent minor r o l e . I n summary, t h e h i g h r a t e s o f energy c o n v e r s i o n and s t o r a g e by t h e above noted a l g a l p r o d u c e r s i s a t t r i b -u t a b l e t o : 1) b e i n g h i g h l y adapted t o and t o l e r a n t o f the e s t u a r i n e environment ( p e r s i s t e n t s p e c i e s - s t r o n g l y e u r y t h e r m a l and e u r y h a l i n e ) o r b e i n g "bloom" s p e c i e s t a k i n g advantage o f optimum c o n d i t i o n s as suggested by K i n g and Schramm (1976) ( s e a s o n a l s p e c i e s - w e a k l y e u r y -t h e r m a l and e u r y h a l i n e ) ; o r 2) b e i n g o f t h a l l o s e o r f i l a m e n t o u s morphology; o r 3) h a v i n g a h i g h p h o t o s y n -t h e t i c e f f i c i e n c y r e l a t i v e t o o t h e r a l g a e , r e s u l t i n g i n h i g h e r net p r o d u c t i o n (energy s t o r a g e ) ; | o r 4) i n t h e case o f A s s o c i a t i o n E, h a v i n g a v e r y h i g h c a l o r i c con-t e n t i n t h e p r e s e n c e o f low net p r o d u c t i o n and p h o t o -s y n t h e t i c e f f i c i e n c y . These f a c t o r s determine p o t e n t i a l i m p o r t a n c e o f a p r o d u c e r t o energy f l o w on the Squamish d e l t a . 105 F i g u r e 14 c l e a r l y shows how Carex l y n g b y e i dominates t h e energy environment a t Squamish. A v a i l a b l e energy from a square meter i s a t l e a s t 4.5 t i m e s t h a t c o n t r i b -u t e d by t h e most p r o d u c t i v e a l g a . The e f f e c t o f ecosystem s t r u c t u r e on t h e magnitude o f energy c o n v e r s i o n and s t o r a g e by v a r i o u s b e n t h i c a l g a e i s e v i d e n t i n F i g u r e 15 which c o n s i d e r s t h e d i s t r i b u t i o n a l a r e a o f each p r o d u c e r . M i c r o a l g a l A s s o c i a t i o n s E and G make t h e g r e a t e s t c o n t r i b u t i o n t o a v a i l a b l e energy r a t h e r t h a n macroalgae as c o n s i d e r e d on a square meter b a s i s . The h i g h energy i n p u t o f A s s o c i a t i o n G ( p r i m a r i l y U l o t h r i x ) , w h i c h had t h e l o w e s t i n p u t p e r square m e t e r , i s a t t r i b u t e d t o growth d u r i n g a p e r i o d o f optimum p h y s i c a l - c h e m i c a l c o n d i t i o n s (low LTD), c o n c u r r e n t w i t h t h e pr e s e n c e o f u n i f o r m s u b s t r a t e r> 2 (Carex) c o v e r i n g some 90 x 10 m . Energy a v a i l a b l e f o r use ov e r t h e y e a r o f 111 x 10^ k c a l r e p r e s e n t e d oa. 43% o f t h e t o t a l a t t r i b u t e d t o b e n t h i c a l g a e . Annual a v a i l a b l e energy f o r A s s o c i a t i o n E o f aa. 104 x 10 k c a l 3 2 over an a r e a o f 10 x 1 0 D m amounted t o 41% o f t h e t o t a l . T h i s h i g h l y p r o d u c t i v e n a t u r e o f sand/mud f l a t d i a t o m a s s o c i a t i o n s has been n o t e d (Pomeroy 1959, W i l l i a m s 1962, G a l l a g h e r and D a i b e r 1974) and w i l l be d i s c u s s e d f u r t h e r . A s s o c i a t i o n s E and G acc o u n t e d f o r 84% o f t o t a l a v a i l a b l e energy o r i g i n a t i n g from b e n t h i c a l g a e . I t i s thus not s i m p l y t h e p r o d u c t i v e c a p a c i t y ( k c a l * -2 -1 m ' y r ) o f an a l g a w h i c h d e t e r m i n e s i t s i m p o r t a n c e t o 106 F i g u r e 15. Energy input (gross p r o d u c t i o n ) f o r each major producer, separated i n t o d i s s o l v e d o r g a n i c , p a r t i c u l a t e o r g a n i c (JJJj) , and r e s p i r a t i o n (f^)• (Minor A s s o c i a t i o n s B and C not i n c l u d e d . ) 107 t h e d e l t a ecosystem but a l s o i t s a b i l i t y t o c o l o n i z e e x t e n s i v e r a t h e r t h a n r e s t r i c t e d h a b i t a t s ( i . e . h a v i n g w i d e r t o l e r a n c e t o l i g h t , s a l i n i t y , d e s i c c a t i o n and t e m p e r a t u r e ) . H i g h l y p r o d u c t i v e s p e c i e s w i t h narrow t o l e r a n c e ranges c o v e r i n g s m a l l a r e a s a r e g e n e r a l l y o f l e s s i m p o r t a n c e ( F i g . 15). B e n t h i c a l g a e r e l e a s e a l a r g e p o r t i o n (up t o 30%) og d a i l y net p r o d u c t i o n as DOM. D e t e r m i n a t i o n s made i n t h i s s t u d y a re c o n s i d e r e d as minimum v a l u e s . Only t h e e f f e c t o f i n c r e a s e d l i g h t was c o n s i d e r e d . Other s t r e s s f a c t o r s shown t o enhance DOM r e l e a s e i n c l u d e t e m p e r a t u r e , s a l i n i t y , d e s i c c a t i o n and subsequent r e - i m m e r s i o n ( S i e b u r t h 1969, Penhale and Smith 1977). A l l t h e s e o p e r a t e a t Squamish, as d i s c u s s e d , which c o u l d l e a d t o even h i g h e r e x u d a t i o n by c h l o r o p h y t e s ( T a b l e 1 3 ) compared t o o t h e r b e n t h i c a l g a e , s u g g e s t i n g t h e former are more t o l e r a n t o f t h e s t r e s s e s o f a t i d a l marsh e x i s t e n c e . P r o - r a t i n g t o t a l net p r o d u c t i o n f o r each month i n d i c a t e s s e a s o n a l s h i f t s I n t h e d i s t r i b u t i o n o f a v a i l -a b l e energy among p r o d u c e r s (Appendix X I I ) . I n t h e f a l l and w i n t e r d i s t r i b u t i o n i s p r i m a r i l y i n A s s o c i a t i o n s E and G (up t o 90%), whereas i n s p r i n g and summer, d i s t -r i b u t i o n i s w i d e r , w i t h more emphasis p l a c e d on macro-a l g a e , e s p e c i a l l y c h l o r o p h y t e s . I n a s i m i l a r f a s h i o n , p r o - r a t i n g o v e r t h e y e a r o f each p r o d u c e r i d e n t i f i e s t h e season o f maximum energy 108 c o n v e r s i o n and s t o r a g e (Appendix X I I I ) . Time o f t h e peak f o r each v a r i e s , a p p r o x i m a t e l y c o i n c i d i n g w i t h i t s c l a s s i f i c a t i o n i n t h e h i g h , medium and low LTD groups ( T a b l e 10). Data from p r o r a t i n g I n d i c a t e t h a t s e a s o n a l d i s t r i b u -t i o n o f energy i n p u t i s such t h a t maximum p e r i o d s a re s t a g g e r e d , r e s u l t i n g i n c o n t i n u a l energy s t o r a g e i n t h e system. However, v a r i a t i o n s i n the magnitude o f t h i s s t o r a g e v a r i e s , c a u s i n g d i s t i n c t s e a s o n a l p a t t e r n s . 3) S e a s o n a l v a r i a t i o n I n energy c o n v e r s i o n and  s t o r a g e . C h a r a c t e r i s t i c energy f l o w p a t t e r n s e x i s t i n f a l l , w i n t e r , s p r i n g , and summer f o r t h e b e n t h i c a l g a l community. These a re based on v a r i a t i o n s I n 1) s o u r c e s o f energy ( s o l a r , t i d a l ) ; 2) ecosystem s t r u c t u r e ( s p e c i e s c o m p o s i t i o n and d i s t r i b u t i o n ) ; and 3) p r o d u c -t i o n p o t e n t i a l (energy c o n v e r s i o n and s t o r a g e ) ( P i g . 16). V a r i a t i o n s i n a l g a l p r o d u c e r s over t h e y e a r ( c h l o r o -p h y t e s - summer, f a l l ; diatoms and phaeophytes - w i n t e r , s p r i n g ) have been d i s c u s s e d and a t t r i b u t e d t o l i g h t , t e m p e r a t u r e , s a l i n i t y and c o m p e t i t i o n . The i n c r e a s e d energy i n p u t o f p e r s i s t e n t p r o d u c e r s such as Monostroma oxyspermum and Enteromorpha minima i n s p r i n g and summer r e f l e c t s t h e pr e s e n c e o f more f a v o r a b l e growth c o n d i t i o n s j u s t as w i t h s e a s o n a l s p e c i e s . T a k i n g d i s t r i b u t i o n a l a r e a o f b e n t h i c a l g a e I n t o a c c o u n t , energy i n p u t and s t o r a g e shows v e r y d e f i n i t e i n c r e a s e s from summer t h r o u g h t o t h e f o l l o w i n g s p r i n g 109 F i g u r e 16. Energy f l o w ( k c a l ' m " .mo" ) t h r o u g h major b e n t h i c a l g a l p r o d u c e r s i n f a l l ( September), w i n t e r (December), s p r i n g (March) and summer ( J u n e ) . Numbers above each b a r r e f e r t o d i s t r i b u t i o n a l a r e a i n square m e t e r s . Cl!\y- Cladophora sp. Em — Enteromorpha minima Ep — E. prolifera Mo — Monostroma oxyepermum R i — Rhizoclonium implexum S — Spirogyra sp. P l — Pylaiella littoralie A — A s s o c i a t i o n A B — A s s o c i a t i o n B C — A s s o c i a t i o n C D — A s s o c i a t i o n D E — A s s o c i a t i o n E F — A s s o c i a t i o n F G — A s s o c i a t i o n G 109a 110 ( T a b l e 21). T h i s i s l o g i c a l i n view o f p a s t d i s c u s s i o n : ; o f ecosystem s t r u c t u r e and t h e c o n t r o l l i n g e f f e c t o f Carex l y n g b y e i on t h e e x t e n t o f t h e b e n t h i c a l g a l com-mun i t y . I t tends t o r e s t r i c t d i s t r i b u t i o n and t o t a l energy i n p u t d u r i n g summer v i a s h a d i n g and promote d u r i n g w i n t e r and s p r i n g by a c t i n g as a s u b s t r a t e . Low r e s p i r -a t o r y c o s t s o f w i n t e r (17%) compared w i t h s p r i n g (35%) i n d i c a t e r e d u c e d s t r e s s and l e s s energy d i v e r t e d t o m e t a b o l i c p r o c e s s e s . W h i t t a k e r (1975) s u g g e s t s t h a t , on t h e a v e r a g e , energy i n p u t i s ca. 1.5 t i m e s energy s t o r a g e f o r a q u a t i c systems. At Squamish, t h i s v a l u e i s 1.6 d u r i n g t h e w i n t e r and 1.38 f o r t h e y e a r . T h i s i s a s l i g h t l y h i g h e r r a t e o f energy s t o r a g e on t h e Squamish d e l t a compared t o o t h e r systems and i s c r e d -i t e d t o t h e d e l t a b e i n g an energy s u b s i d i z e d ecosystem. B. Annual energy f l u x and g e n e r a l ecosystem f u n c t i o n . Energy c o n v e r s i o n and s t o r a g e by t h e major a u t o -t r o p h i c components ( v a s c u l a r p l a n t s and b e n t h i c a l g a e ) on t h e Squamish d e l t a have been c o n s i d e r e d , a l o n g w i t h c o n t r o l l i n g p h y s i c a l - c h e m i c a l f a c t o r s . Combining t h i s w i t h d a t a on energy l o s s ( o r g a n i c r e m o v a l ) , u t i l i z a t i o n -( g r a z i n g and d e t r i t a l f e e d i n g ) , and r e t e n t i o n ( i n c o r -p o r a t i o n i n t o s e d i m e n t s ) , i t i s p o s s i b l e t o d i s c u s s p a t h -ways o f energy f l u x f o r t h e p r i m a r y l e v e l o f t h e Squamish d e l t a ecosystem. T a b l e 21. T o t a l energy Input ( g r o s s p r o d u c t i o n ) , s t o r a g e (net pr o d u c -t i o n as DOM, POM), and l o s s e s ( r e s p i r a t i o n ) f o r b e n t h i c a l g a l p r o d u c e r s i n f a l l , w i n t e r , s p r i n g and summer as k c a l x 10J,mo 'study a r e a F a l l W i n t e r S p r i n g Summer (September) (December) (March) (June) k c a l - 1 0 3 % k c a l - 1 0 3 % k c a l - 1 0 3 % k c a l - 1 0 3 Gross P r o d u c t i o n 2453 .9 2905.3 6588.0 2144 .4 (energy i n p u t ) R e s p i r a t i o n 629-9 26 493.6 17 2304.7 35 543-9 28 (energy l o s s ) Net P r o d u c t i o n (energy s t o r a g e ) DOM 190.7 8 387.0 13 436.0 7 190,7 9 POM 1637.3 66 2024 .7 70 3847.3 58 1359.8 63 112 Two h a b i t a t s can be i d e n t i f i e d on t h e Squamish d e l t a based on d i f f e r e n c e s i n s t r u c t u r e and e n e r g e t i c s . The sand/mud f l a t s h a b i t a t o f t h e l o w e r i n t e r t i d a l i s s i m p l e w i t h r e s p e c t t o s t r u c t u r e and energy f l u x (move-ment), whereas t h e Carex m a r s h l a n d i n t h e mid-upper i n t e r t i d a l i s much l a r g e r and more complex. Energy f l u x t h r o u g h a square meter o f each i s d i s c u s s e d . Sand/mud f l a t h a b i t a t . E n e r g e t i c s o f t h i s a r e a ar e based on a s i n g l e p r o d u c e r , t h e d i a t o m dominated A s s o c i a t i o n E. A p p r o x i m a t e l y %1% o f t o t a l energy i n p u t and s t o r a g e r e s u l t i n g from t h e a c t i v i t y o f b e n t h i c a l g a e comes from c o n t i n u e d p r o d u c t i o n o f t h i s a s s o c i a t i o n t h r o u g h o u t t h e y e a r ( T a b l e 22). A v a i l a b l e energy — 2 —1 (850 k c a l ' m «yr ) from net p r o d u c t i o n and o r g a n i c a d d i t i o n amounts t o aa. 78% o f t o t a l energy i n p u t . Over h a l f o f t h e a v a i l a b l e energy i s removed, e i t h e r as DOM o r POM t o t h e s u r r o u n d i n g e s t u a r y and w a t e r s o f Howe Sound. A p p r o x i m a t e l y 17% i s r e t a i n e d and i n c o r p o r a t e d i n t o t h e s u b s t r a t e where i t e i t h e r a c t s as a f o o d s o u r c e f o r m i c r o - o r g a n i s m s o r i s permanently l o s t i n t h e sediment. A t u r n o v e r time o f f o u r days f o r A s s o c i a t i o n E, th e most r a p i d on t h e d e l t a , p l u s low r e t e n t i o n o f energy suggest t h e sand/mud f l a t h a b i t a t t o be v e r y e f f i c i e n t i n terms o f energy c y c l i n g . Net p h y t o -p r o d u c t i o n f o r t h e y e a r ( g r o s s p r i m a r y p r o d u c t i o n + o r g a n i c a d d i t i o n ) - ( r e s p i r a t i o n + o r g a n i c removal) 113 Table 22. Annual energy flux for sand/mud f l a t s (area = 2 2 15875 m ) and sedge marshlands (area = 111125 m ). Sand f l a t s Marshland -2 -1 kcal'm «yr above below ground ground -2 -1 kcal-m «yr A. Input Gross primary production benthic algae 910 178 vascular plants - 9416 8347 Added organic matter 185 543 -B. Losses 1095 10137 8347 t o t a l = 18484 Respiration benthic algae 245 36 vascular plants - 4708 4173 Losses to turnover vascular plants - 471 Removed part i c u l a t e organic matter 170 2350 Exuded organic matter 86 154 Unmeasured13 grazing and unde-tected removal 404 1480 Incorporation i n sediment 190 930 4173 1095 10137 8347 t o t a l = 18484 a assume r e s p i r a t i o n of Carex = 50% obtained by difference (Input - other expenditures) c assume oa. '.%% going to grazing ^ Including 3% of vascular plant net production as DOM of 141 kcal 114 amounts to +239 kcal'm or 22% storage of t o t a l energy input on the delta. This i s a measure of the net change (storage or loss) i n the amount of carbon held by a system and i s valuable i n appraising function (Woodwell et a l . 1973). In t h i s case, i t i s further i n d i c a t i o n of a strongly exporting habitat. Carex marshland. The Carex marsh habitat i s separ-ated into above and below ground components as dictated by structure, energy input, storage and u t i l i z a t i o n . Above ground energy input i s d i s t r i b u t e d between Carex (93%), benthic algae (2%), and added organics (5%), together contributing oa. 10 times the energy per square meter of the sand/mud f l a t s (Table 22). The greater addition of organic matter over that of the f l a t s Is due to the "trapping" nature of the Carex, causing p a r t i c l e s to s e t t l e out. Available energy (net production and added organics) amounts to oa. 54$ of input, a drop of 27% over that found on the f l a t s but a s u b s t a t i a l increase i n terms — 2 —1 of actual energy (5474 kcal'm yr ). Higher rates of r e s p i r a t i o n plus a turnover time averaging 19 days (Appendix X) are responsible for the drop i n energy storage e f f i c i e n c y . However, of t h i s stored energy, an estimated 67% i s removed from the delta to surrounding waters, or oa. eight times that contributed by the sand/mud f l a t s . The importance of the marshland i s emphasized. 115 C a l c u l a t i o n o f net p h y t o - p r o d u c t i o n g i v e s a v a l u e — 2 —1 o f +1338 kcal'm «yr o r 12% o f t o t a l energy i n p u t . T h i s i n d i c a t e s t h a t t h e marsh i s even more h i g h l y e x p o r t -i n g i n n a t u r e t h a n t h e sand/mud f l a t s i n terms o f p e r c e n t and a c t u a l c o n t r i b u t i o n s . I n c o n t r a s t , the below ground p o r t i o n o f t h e marsh appears as a v i r t u a l l y i s o l a t e d system w i t h no a d d i t i o n ( i m p o r t ) and l i t t l e r emoval o f m a t e r i a l except sedge rhizomes at t h e p e r i p h e r y o f t h e d e l t a ( T a b l e 22). Combining d a t a from t h e sand/mud f l a t h a b i t a t and t h e Carex marsh, i t i s c l e a r t h a t Squamish i s a v a s c u l a r p l a n t dominated system, w i t h o n l y ca. 3% o f energy Input due t o b e n t h i c a l g a e . The sand/mud f l a t h a b i t a t p l a y s a v e r y minor r o l e i n t o t a l energy f l u x , a d d i n g a maximum o f 1.4% o f t h e energy. The e s t i m a t e d v a l u e o f 3% i s c o n s i d e r e d t o be an u n d e r e s t i m a t e due t o methodology used i n t h i s s tudy ( I . e . i n c u b a t i o n o f samples i n w a t e r ) . Johnson et a l . 'lM3%k) i n d i c a t e p r o d u c t i o n o f b e n t h i c a l g a e from th e mid-upper i n t e r t i d a l t o be 1.6 - 6.6 t i m e s g r e a t e r i n a i r t h a n i n w a t e r . However, d e s i c c a t i o n r educes t h e degree o f p r o d u c t i o n i n a i r . A l g a e a t Squamish e x p e r -i e n c e c o n s i d e r a b l e d e s i c c a t i o n a t low t i d e d u r i n g t h e summer due t o wind and h i g h t e m p e r a t u r e s . T h e r e f o r e , assuming an i n c r e a s e o f f o u r t i m e s w a t e r p r o d u c t i o n , i n a i r , and exposure o f t h e a l g a e a t low t i d e d u r i n g t h e day f o r ca. 50% o f t h e i r growth p e r i o d , net p r i m a r y 116 production for benthic algae could amount to oa. 7% rather than 3%• This estimate of net production, taking a i r into account i s considered r e a l i s t i c i n view of the fact that not a l l algae show increased production i n a i r . Species from the lower i n t e r t i d a l areas ( i . e . P y l a i e l l a l i t t o v a l i s and' some microalgal associations) often show reduced rates of production (Johnson et al. 1974). Increasing energy input attributable to benthic algae to 7% approximates an estimate of 8% made for benthic algae on the Nanaimo estuary (SIbert and Naiman, unpublished data). However, t h i s value must also be increased to account for production on exposure, increa-sing i t to oa. 15%. On both the Nanaimo and Squamish estuaries i n t e r t i d a l microalgae play a larger role than do macroalgae, a fact which may r e f l e c t greater a v a i l -able habitat and growth e f f i c i e n c y . Pew studies exist comparing energetics of benthic algae and vascular plants on deltas. Teal (1962), preparing an energy budget for a s a l t marsh i n Georgia, estimated that of t o t a l available energy, benthic algae (primarily sand/mud f l a t diatoms) accounted for 25%. More recently, Gallagher and Daiber (1973, 1974) report an estimate of 25 - 30$ for benthic algae r e l a t i v e to Spartina for a Delaware s a l t marsh. The projected value of 7% estimated for the Squamish delta i s much lower In comparison. This may be due to: 1) an overestimate of gross production by Carex ( i . e . assuming 50% 117 r e s p i r a t i o n ) , 2) a v a r i a t i o n i n a l g a l s p e c i e s and r e s t r i c t e d d i s t r i b u t i o n o f h i g h l y p r o d u c t i v e d i a t o m a s s o c i a t i o n s due t o s h a d i n g by sedge and c o v e r i n g by sediment d u r i n g f r e s h e t , and 3) a more n o r t h e r l y l o c a t i o n , r e s u l t i n g i n reduced s o l a r energy and c o n v e r -s i o n r a t e s . I n a t i d a l marsh system dominate by Carex l y n g b y e i I t i s t h e manner i n which energy i s put i n t o t h e system by b e n t h i c a l g a e r a t h e r t h a n t h e a b s o l u t e amount t h a t i s t h e i m p o r t a n t f e a t u r e ( I . e . f l u x r a t h e r t h a n s t a n d i n g crop b i o m a s s ) . B e n t h i c a l g a e a c t as c o n t i n u a l l y p r e s e n t , r e a d i l y a v a i l a b l e s o u r c e s o f energy d i r e c t l y u t i l i z a b l e by a t l e a s t one major consumer on t h e d e l t a (amphipods). A l t e r n a t i v e l y , on r a p i d breakdown, a l g a e c o n t r i b u t e energy t o t h e g e n e r a l d e t r i t a l pathway. There i s l i t t l e l a g between t h e time o f c o n v e r s i o n and u t i l i z a t i o n o f s t o r e d energy. C. l y n g b y e i d i s p l a y s a d e f i n i t e t ime l a g between p r o d u c t i o n , d e c o m p o s i t i o n , and u t i l i z a t i o n . Thus, t h e marsh may be r e g a r d e d as a l a r g e energy r e g u -l a t o r w i t h h i g h energy s t o r a g e and ti m e d r e l e a s e t h r o u g h -out t h e y e a r . Energy f l o w and ecosystem f u n c t i o n a t Squamish a r e c y c l i c i n n a t u r e , as summarized i n F i g u r e 17. Some o f t h e i m p o r t a n t f e a t u r e s w i l l be d i s c u s s e d . The b u l k o f energy c o n v e r s i o n and s t o r a g e , above and below ground, o c c u r s by C. l y n g b y e i i n s p r i n g and summer. D u r i n g t h i s p e r i o d l i t t l e consumption o f l i v i n g m a t e r i a l o c c u r s , 118 a s i d e from t h a t g o i n g t o as y e t u n i d e n t i f i e d i n v e r t e b r a t e s and i n s e c t s ( 5%, C. D. L e v i n g s , p e r s o n a l communication). Anisogammarus oonfervioolus , an Important consumer on the d e l t a (Anonymous 1972), i s not a b l e t o u t i l i z e Carex lyngbyei u n l e s s f i r s t decomposed ( T a b l e 17, Chang 1975). Low l e v e l r e l e a s e o f DOM (4%) o v e r t h e l a r g e growth a r e a c o u l d have a c o n s i d e r a b l e impact on ecosystem f u n c t i o n by a c t i n g as an energy s o u r c e f o r b a c t e r i a , w h i c h a r e u t i l i z e d by f i l t e r and d e t r i t a l f e e d e r s . T u r n e r (1974) and G a l l a g h e r et al. (1976) I n d i c a t e t h e Importance o f t h i s pathway i n e s t u a r i e s dominated by Spartina alter-n i f l o r a , s u g g e s t i n g t h a t much o f t h e DOM I s m e t a b o l i z e d w i t h i n t h e marsh ecosystem. C o n t r a r y t o t h i s , P enhale and Smith (1977), w o r k i n g w i t h Zostera, b e l i e v e t h a t t h e m a j o r i t y o f DOM i s f l u s h e d out o f t h e e s t u a r y by t i d a l a c t i o n . Low l e v e l s o f DOM i n wate r s a d j a c e n t t o t h e d e l t a and i n upper Howe Sound suggest r a p i d uptake and in situ u t i l i z a t i o n , as i n d i c a t e d by G a l l a g h e r et al. (1976) f o r s a l t marshes. More s t u d y i s needed i n t h i s a r e a o f energy s t o r a g e and u t i l i z a t i o n . Energy i n p u t by b e n t h i c a l g a e I s low d u r i n g s p r i n g and summer, b e i n g r e s t r i c t e d by t h e pr e s e n c e o f v a s c u l a r p l a n t g r o w t h , hi;gh l i g h t , t e m p e r a t u r e and low s a l i n i t y ( F i g . 17). I t s i m p o r t a n c e a t t h i s t i m e , as th r o u g h o u t the y e a r , I s as a r e a d i l y a v a i l a b l y f o o d s o u r c e . R e s u l t s from t h i s s t u d y i n d i c a t e p r e f e r e n t i a l f e e d i n g on f i l a -mentous (Pylaiella l i t t o r a l i s and Enteromorpha minima) 119 F i g u r e 17. Seasonal p a t t e r n o f energy storage (net p r o d u c t i o n ) by Carex lyngbyei and b e n t h i c a l g a e , energy removal as POM and the r a t i o o f energy outflow/energy Inflow. 119a in o 20-15-"x10 5H Carex (net production) 40 30H 104 ©-T r Benthic algae (net p r o d u c t i o n ) CM O 20-15-:io-8 6-I 4 2H © POM .removed @ ~i 1 1 r -JEnergy^Outflow Energy.Jnf low 1 1 1 S 0 N D ® & 1 1 1 I J F M A M • "j r J J i r 1974 1975 120 and, to some ex t e n t , t h a l l o s e (Monostroma oxyspermum) algae by amphipods (Table 17). Peak biomass o f f i l a -mentous algae approximately c o i n c i d e s w i t h that-'for j u v e n i l e amphipods which r e a d i l y consume such s p e c i e s as Pylaiella l i t t o r a l i s under l a b o r a t o r y c o n d i t i o n s . Chang (1975) suggests the need f o r algae i n the d i e t o f amphipods f o r maximum growth and s u r v i v a l . Data from f e e d i n g s t u d i e s based on f a t t y a c i d a n a l y s i s i n d i c a t e i n g e s t i o n o f algae under f i e l d c o n d i t i o n s . In a d d i t i o n t o an energy source, b e n t h i c a l g a e , p r i m a r i l y Pylaiella l i t t o r a l i s and Enteromorpha minima, serve as s i t e s o f cover at low t i d e , p r e v e n t i n g d e s i c c a t i o n o f amphipods remaining on the marsh s u r f a c e at low t i d e (Tables 16, 17). A s s o c i a t i o n s o f b e n t h i c algae and other consumers s i m i l a r to t h a t d e s c r i b e d f o r amphipods l i k e l y e x i s t . S t u d i e s o f t h i s nature are r e q u i r e d to f u r t h e r i n d i c a t e the f u n c t i o n o f b e n t h i c algae in> a Carex marsh ecosystem. Removal o f POM i s h i g h i n s p r i n g and summer ( F i g . 17), r e f l e c t i n g i n c r e a s e d decomposition r a t e s . Removal i s g r e a t e r by an average o f 10 times on the marsh com-pared to the sand/mud f l a t s (Table 15). The o r i g i n of the POM can be t r a c e d to algae present on the d e l t a and p r i m a r i l y to Carex produced the p r e v i o u s year. Decompo-s i t i o n remains low over the w i n t e r , showing i n c r e a s e s i n s p r i n g and summer i n response to h i g h e r temperatures and l i g h t and i n c r e a s e d a c t i v i t y and abundance o f grazer-decomposer organisms. P r e l i m i n a r y s t u d i e s done 1 2 1 In t h i s t h e s i s on POM show the amount and composition o f m a t e r i a l removed from the d e l t a to be a f u n c t i o n o f growth, s u b s t r a t e - h a b i t a t type (Table 1 5 ) , c u r r e n t and wave a c t i o n , depth o f water i n t i d a l creeks (Table 14), and type o f area d r a i n e d by the creeks ( P i g . 1 2 ) . High v a r i a b i l i t y thus e x i s t s over the d e l t a with r e s p e c t t o POM removal (Dewitt and Dalber 1 9 7 3 , Odum et al. 197-2. Boon 1 9 7 5 , Erkenbrecher and Stevenson 1 9 7 5 , Gardner 1 9 7 5 ) . S h i s l e r and Jobbins ( 1 9 7 7 ) note similar', problems i n s a l t marshes o f the e a s t e r n U n i t e d S t a t e s . T e a l ( 1 9 6 2 ) , Odum and de l a Cruz ( 1 9 6 7 ) , Biggs and Plemer ( 1 9 7 1 ) , Heald ( 1 9 7 D , Mann ( 1 9 7 2 a ) , R i l e y ( 1 9 7 3 ) , S c h u l t z and Quinn ( 1 9 7 3 ) , V a l i e l a and T e a l ( 1 9 7 4 ) and H e i n l e et al. ( 1 9 7 7 ) a l l note the importance o f POM to s a l t marshes and e s t u a r i e s . As judged from r e s u l t s at Squamish on p r o d u c t i o n and removal r a t e s o f POM, i t s importance i n e s t u a r l n e ecosystems dominated by Carex t i d a l marshes i s as great as i n s a l t marshes. The m a j o r i t y o f POM produced over the year i s removed from the d e l t a (dt. 7 0 % ) Table 2 2 ) . K i r b y and Go s s e l i n k ( 1 9 7 6 ) suggest a s i m i l i a r r a t e o f removal f o r POM i n a Lousiana s a l t marsh dominated by Spartina alterniflora. However, de l a Cruz ( 1 9 7 3 ) r e p o r t s a removal r a t e o f only 21% f o r a s i m i l i a r marsh i n Georgia. V a r i a t i o n may be a r e s u l t o f the f a c t o r s noted at the top o f t h i s page. The p o r t i o n o f POM r e t a i n e d on the d e l t a afe Squamish becomes i n c o r p o r a t e d i n t o the upper l a y e r o f the marsh d u r i n g heavy sedimentation at f r e s h e t 122 (June-July). Approximately 40-50% of what i s i n -corporated i s mobilized by micro-organisms and returned to the system to pa r t i c i p a t e i n estuarine processes. The remaining energy i s l o s t i n a "sediment sink" of varying depth, indicated by l i t t l e change i n organic content ( i . e . beyond depth of reworking). Biggs and Flemer (1972) also indicate a mobilization of ca. 50%. Addition of POM to the delta i s also highest i n spring and summer (Fig. 17) and variable from sand/mud f l a t s to Carex marsh (Fig. 11). A greater proportion of macroalgae are added to the marsh i n response to the f i l t e r i n g nature of Carex,. It i s acting as a trap for energy (organic matter) entering from external sources and a retention mechanism for energy stored and broken down on the delt a . In thi s way, energy i s available for the marsh ecosystem and not t o t a l l y removed by the twice d a i l y t i d a l flushing. Retention of a larger proportion of detritus on the sand/mud f l a t s r e f l e c t s a reduced a b i l i t y to trap large p a r t i c l e s ( i . e . macro-algae). The nature of the substrate, large sand to mud, favors settlement and Incorporation of d e t r i t u s . The r a t i o of energy removal/energy storage (net production + organic addition) i s a good i n d i c a t i o n of energy flux throughout the year (Fig. 17). A r a t i o < 1.0 r e f l e c t s accumulation of energy, whereas>1.0 r e f l e c t s removal i n excess of storage. Based on thi s r a t i o , spring and summer are times of high energy accum-123 ul a t i o n whereas f a l l and winter are times when the estuarine ecosystem i s drawing heavily on stored energy (Fig. 17). The only source of energy input v i a primary produc-t i o n to the delta during f a l l and winter are benthic algae (Fig. 17). Total conversion and energy storage reaches i t s peak during the winter when the competitive action of Carex i s at a minimum and low LTD tolerant algae (Table 10) can colonize and add to energy storage. POM removal i s low during the f a l l , an i n d i c a t i o n that much of the Carex from the previous year has oeen removed, leaving minimal amounts on tne delt a . Increase i n POM removal over the winter p a r a l l e l s increased a l g a l growth and may oe r e f l e c t i n g tne onset of breakdown of the present year's crop of Carex (Levlngs and Moody 1976) by decomposers favoring lower temperatures. Amplifying removal rate are increased wave and current action i n winter. The below ground portion of the marsh was described s t r u c t u r a l l y and from an energy flux standpoint as a separate unit c o n t r i D U t i n g l i t t l e to energy flux i n the estuarine ecosystem. However, seasonal changes exist i n energy stored i n tne rnizomes. Bernard (1974; and Bernard and MacDonald (1974; note a negative production ( i . e . u t i l i z a t i o n of stored energy; i n winter through to the next growing season for species of Carex occur-rin g i n wetland s i t u a t i o n s . This i s also considered to be the case for Carex at Squamish. Breakdown of rhizomes 124 below ground p r o v i d e s energy f o r organisms w h i c h rework t h e s e d i m e n t , r e l e a s i n g n u t r i e n t s and o r g a n i c m a t e r i a l t o t h e s u r f a c e . I n l i g h t o f t h e s e f e a t u r e s , the below ground p o r t i o n o f t h e marsh i s seen as Important i n above ground ecosystem s t r u c t u r e and f u n c t i o n . I I I . The Squamish R i v e r D e l t a as a  P r o d u c t i v e , Energy R i c h Ecosystem The Squamish R i v e r d e l t a I s a v e r y dynamic system, a n n u a l l y c o n v e r t i n g , s t o r i n g and c o n t r i b u t i n g l a r g e amounts o f energy t o t h e s u r r o u n d i n g e s t u a r y . P r i m a r y pathways o f energy f l u x are.summarized I n F i g u r e 18 f o r ease o f u n d e r s t a n d i n g . I t i s c l e a r t h a t t h e d e l t a I s a d e t r i t a l - b a s e d s ystem, w i t h most o f t h e energy i n p u t and s t o r a g e a t t r i b u t a b l e t o v a s c u l a r p l a n t s growing, on t h e t i d a l marsh ( F i g . 18, T a b l e 2 2 ) . S m a l l e y (1959), Odum (1963), Odum and de l a Cruz (1963), and Pomeroy et al (1969) note s i m i l a r f i n d i n g s i n G e o r g i a s a l t marshes. I n t h e s e marshes, 70 - 90% o f a v a i l a b l y energy g o i n g t o d e t r i t u s o r i g i n a t e s from s p e c i e s o f Juncue and S p a v t i n a . Zieman (1975) r e p o r t s 90% o f p r o d u c t i o n from t u r t l e g r a s s beds i n F l o r i d a e n t e r s t h e a i d e t r i t a l c h a i n . These d a t a a re comparable t o those from Squamish, w h i c h i n d i c a t e s ca. 90% I n p u t o f v a s c u l a r p l a n t p r o d u c t i o n t o t h e d e t r i t a l c h a i n . 125 F i g u r e 1.8. Proposed energy f l u x t h r o u g h Carex l y n g b y e i (above and below ground) and b e n t h i c a l g a e . R e l a t i v e p e r c e n t a g e s d e r i v e d from T a b l e 22 r e p r e s e n t f l u x I n a " c h a r a c t e r i s t i c " square meter o f d e l t a s u r f a c e . Energy r e m a i n i n g a f t e r r e s p i r a t o r y c o s t s a r e removed i s p a r t i t i o n e d i n t o g r a z i n g , DOM and POM, r e p r e s e n t i n g a t o t a l 100% o f a v a i l a b l e energy. POM i s s i m i l a r l y p a r t i t i o n e d . (TS = t i d a l energy s u b s i d y , AO = added o r g a n i c m a t t e r , PAR = p h o t o s y n t h e t i c a l l y a v a i l a b l e r a d i a t i o n ) . 126 Benthic algae with t h e i r low energy input and storage (3%) primarily function as:;. 1) an energy source for s p e c i a l i z e d consumers, 2) a possible requirement i n the diet of certain invertebrates (e.g. amphipods (Chang 1975)) and 3) an a u x i l i a r y source of d e t r i t u s , being most abundant when breakdown of Carex i s thought to be lowest. Large amounts of DOM, from sources indicated i n Figure 18, supply ample substrate for heterotrophic a c t i v i t y , promoting vascular plant breakdown. Pomeroy et a l . (1975) provide an excellent discussion and indicate the "importance of DOM to microbial a c t i v i t y i n estuaries. The proportion r e s u l t i n g from benthic a l g a l exudation Is minimal and may function more i n i n t e r -species competition with other algae or i n determining species composition of associated consumers. Particulate organic matter, which forms the base of the d e t r i t a l food chain, originates primarily from vascular plants (Fig. 18). It i s estimated that aa. ^9% of energy available as POM i s removed from the delta to function i n the d e t r i t a l food chain of the surrounding estuarine ecosystem. This value compares very well with the estimate of 45% by Teal (1962) for a Georgia s a l t marsh. Approximately 18% of available energy i s u t i l i z e d by d e t r i t i v o r e s on the delta as i t i s produced. This estimate of " i n e i t u " u t i l i z a t i o n i s lower than those 127 given by Teal (1962) f o r a Georgia s a l t marsh and Thayer et al. (1975) for an eelgrass (Zostera marina) bed i n North Carolina. Both studies indicate 55$ u t i l i z a t i o n by consumers. The greater use may r e f l e c t the presence of more consumers (micro- and macrofauna) and the breakdown of Zostera and Spartina to a more usable form compared to Carex. Due to heavy sedimentation at Squamish, i t i s estimated that ca. 33% of available energy (POM) i s retained on the d e l t a and becomes incorporated into the sediment (Fig. 18). Mobilization by decomposers occurs slowly, returning ca. 50% to the system as nut-r i e n t s , etc. An equal amount remains trapped i n the sediment along with aa. 50% of the energy stored i n Carex rhizomes. The remaining 50% i n Carex Is returned to the system v i a the action of decomposers (Fig. 18). Some data exist i n the l i t e r a t u r e with which to compare Squamish i n terms of primary production. The Carex t i d a l marsh,which dominates t o t a l energy flow on the d e l t a , i s among the most productive of those reported In the l i t e r a t u r e (Levings and Moody 1976) (Table 23). —2 —1 An average of ca. 550 g C«m *yr (Appendix XI) exceeds estimates for wetlands In the i n t e r i o r of B r i t i s h Colum-bi a . Higher production rates are attributed to abundant nutrients (Bernard 1973)^retained and rapidly recycled (Odum 1971); daytime emersion during productive parts of the year; low s a l i n i t y , reducing metabolic stress; and the benefits of a t i d a l energy subsidy. — 2 —1 T a b l e . 23. Comparison o f net p r o d u c t i o n (energy s t o r a g e ) as g C*m «yr f o r Carex lyngbyei and v a s c u l a r p l a n t s o f o t h e r marsh a r e a s . L o c a t i o n H a b i t a t Net P r o d u c t i o n R e f e r e n c e (energy s t o r a g e ) P c • -2 -1 | C-m -yr Squamish R i v e r D e l t a B r i t i s h Columbia P r a s e r D e l t a B r i t i s h Columbia Western New York USA San F r a n c i s c o Bay C a l i f o r n i a New E n g l a n d , Mary-l a n d , V i r g i n i a Sapel'dElsland G e o r g i a B r i d g e w a t e r Bay S o u t h e r n E n g l a n d Carex lyngbyei t i d a l marsh C. lyngbyei t i d a l marsh C. laoustris w e t - l a n d Spartina foliosa s a l t marsh S. alterniflora s a l t marsh S. alterniflora s a l t marsh S. alterniflora s a l t marsh 550 450 735 135 - 345 215 - 690 1600 380 L e v l n g s and Moody 1976 Yamanaka 1975 B e r n a r d and MacDonald 1974 M a h a l l and Par k 1976 N i x o n and O v i a t t 1973b Keefe and Boynton 1973 T e a l 1962 R a n w e l l 1961 Puget Sound Washington Zostera marina marine 518 P h i l l i p s 1974 129 The estimated net production of Carex l y n g b y e i i s s i m i l a r to values given i n the l i t e r a t u r e for S p a r t i n a spp. on s a l t marshes of the United States. The l a t t e r are among the most naturally productive ecosystems (Odum 1971). Comparative data for benthic a l g a l production i n t i d a l and s a l t marsh estuarine ecosystems are not that abundant i n the l i t e r a t u r e . Estimates r e l a t i n g to diatom-dominated miscroalgal associations are best documented (Table 2k). Net production estimates deter-mined Itor Squamish appear somewhat lower than those f o r other estuarine and marine i n t e r t i d a l s i t u a t i o n s . This i s a r e f l e c t i o n of a more northerly l o c a t i o n , with reducedophotosynthetically available r a d i a t i o n , and l i k e l y variations i n species composition of the micro-a l g a l associations. Taken as a unit, the Squamish River delta ranks among the most highly productive naturally occurring ecosystems. This may be attributed t o : t l ) presence of a t i d a l energy subsidy, reducing energy going to meta-b o l i c processes; 2) extreme nature of the environment, which selects for species well adapted to year round existence or. opportunistic species with high productivity fo r a short period; and $) continual input of energy into the system by benthic algae. Schelske and Odum (1961) note s i m i l a r reasons behind the high productivity of Georgia s a l t marshes. ? 1 Table 24. Comparisons of net production (energy storage) as g Cm" *yr f o r diatom-dominated microalgal associations i n estuarine and marine habitats. Location Habitat Net Production Reference (energy storage) -2 -1 g Cm «yr Squamish River Delta B r i t i s h Columbia Deleware, USA Duplin River marsh Georgia, USA Great Sippewissett Marsh, Falmouth, Massachusettes, USA Washington, USA Denmark sand/mud f l a t Carex t i d a l marsh salt marsh Spartina a l t e r -n i f l o r a dominated s a l t marsh sal t marsh i n t e r t i d a l marine sand f l a t s i n t e r t i d a l marine sediments 114 150* 60l 190^ 274 d 143 - 226 115-178 estimated from Appendix VIII t h i s study Gallagher and Daiber 1974 Pomeroy 1959 Van Raalte et a l . 1968 Pamatmat 1968 Grontved i960 a average over a square meter of marsh surface b assume re s p i r a t i o n = 25$ gross production c assume res p i r a t i o n = 10% gross production maximum value ;based on estimate of 75 mg Cm" «hr~ 131 LITERATURE CITED A d m i r a a l , W. 1977. 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Date 1974 2 0 June 5 July 1 9 July 1 1 August 2 7 August 2 September 1 3 September 1 7 October 3 0 October 2 2 November 1 8 December 1 9 7 5 2 2 January 2 0 February 1 9 March 16 A p r i l 14 May 1 2 June 1 6 July 2 9 July 1 3 August 1 5 cm below water surface Depth 0 m a lm 2m 40 9 1 6 0 1 0 1 6 5 1 0 2 7 0 1 5 5 7 5 2 0 8 7 5 2 2 1 0 8 0 2 5 1 5 90 30 18 90 3 7 2 3 90 3 5 2 5 9 0 3 8 24 9 0 3 6 2 2 9 0 5 4 2 8 9 2 3 8 2 0 8 0 2 6 1 0 8 6 3 0 1 3 7 0 8 1 6 5 1 0 1 5 5 8 2 7 0 2 0 1 0 Appendix II. S a l i n i t y , temperature and incident r a d i a t i o n (PAR). Date Depth S a l i n i t y ' (m) °/oo Temperature Light water a tide p o o l b a i r (PAR) 1974 1975 21 June 19 July 20 August 18 September 17 October 17 November 17 December 21 January 19 February 0' 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 3.5 4.0 4.3 4.8 1.2 1.7 5.8 9.0 22.2 24.5 11.5 12.0 5.1 5.8 27.3 27.5 25.6 27.5 9.0 10.2 10.6 12.0 10.7 8.6 8.8 8.5 10.5 4.0 4.7 5.8 6.0 5.2 5.7 17.9 14.0 192.4 17.4 15.1 174.0 17.9 17.8 140.0 15.4 15.6 125.4 10.1 109.8 4.5 3.4 0.1 32.8 25.9 19.8 0.6 32.7 .... Continued Date Depth S a l i n i t y a (m) °/oo water' 19 March 0 9.0 1 16.0 -18 A p r i l 0 6.2 7.9 1 12.6 9.0 15 May 0 4.0 8.6 1 6.0 -20 June 0 2.5 9.1 1 3.0 -1.6 July 0 1.8 10.0 1 2.9 10.8 13 August 0 2.0 11.4 1 3.1 11.8 Temperature Light a t i d e p o o l b a i r (PAR) 8.0 4.1 39.0 12.0 7.6 U7.0 14.7 10.9 180.0 18.2 13.8 289.0 17.4 17.5 271.2 19.3 20.5 175.0 £ C7\ from Levlngs et a l (1976) k determined with a standard mercury thermometer 15 cm below water surface Appendix I I I . Nutrient concentrations i n t i d a l creeks (see Pig. 3 for sampling locations) (ug-at•1-1). Date Creek a NO" NHt PO -3 4 pH Level P i l e Snag P i l e Snag P i l e Snag 1974 19 July H 2.41 1.83 4.14 7.19 1.32 1.19 6.98 M 2.77 2.17 3.10 9.41 0.99 0.79 6.90 L 2.01 1.92 4.92 6.03 1.17 1.02 6.94 2 September H 0.50 0.21 3.40 5.71 2.30 1.72 7.08 M 1.12 0.74 3.90 6.33 2.49 1.98 7.12 L 0.74 0.37 2.49 5.46 1.90 1.32 7.10 1975 22 January H 31.40 - 1.74 — 4.39 — 7.66 M 39.90 27.29 3.12 3.98 4.90 3.17 7.55 L 33.71 21.07 2.94 3.14 4.19 2.88 7.58 19 A p r i l „ H 3.93 4.39 1.39 2.75 0.94 1.19 7.67 M 4.80 5.12 2.43 3.91 1.32 1.98 7.62 L 4.17 4.72 2.01 3.49 0.89 0.94 7.69 12 June H 1.92 1.35 6.21 9.42 9.72 1.12 7.15 M 4.71 2.99 7.49 12.31 0.91 1.401 7.16 L 3.12 2.42 5.12 9.99 0.61 1.19 7.19 M •Cr H=just below delta surface M=mid creek l e v e l L=creek bottom 148 Appendix IV. Annual sedimentation rates and sediment organic content (LOI) determined from cores taken i n 1974 from locat ions indicated below. A. S p a t i a l v a r i a t i o n i n mean sedimentation r a t e s . Area Core numbers Mean sediment- Area descr ip t ion ation^yr"^ (cm) A 1-4 2.25 sand f l a t , low i n t e r t i d a l B 5-8 2.56 Eleocharis p a l u e t r i s , consol idated mud, m i d - i n t e r t i d a l C 9-12 2.06 Carex lyngbyei t a l l growth (0.5-1.5 m) consol idated mud, m i d - i n t e r t i d a l D 13-16 1.79 C. l y n g b y e i short growth (<0.5 m), consol idated mud, m i d - i n t e r t i d a l E 17-20 2.03 creek bottom, uncon-so l idated mud, low i n t e r t i d a l P 21-24 1.58 dead zone, strongly decomposing, unconsol-idated mud, upper i n t e r t i d a l G 25-28 - a P o t e n t i l l a p a o i f i c a zone, compact humid sediment, upper inter-t i d a l ct years not i d e n t i f i e d , » s e c t i o n e d i n cm i n t e r v a l s 149 Appendix IV B. Year of deposition, depth, and LOI. Core Area A Area B Area C Area D Year Depth L 0 l a Percei ;posited i n t e r v a l (mg C*g LOI (cm) dry wtT 1) 1974 1.50 11.6 2.4 73 1.00 11.7 2.4 72 1.00 10.7 1.8 71 2.50 10.9 2.3 70 3.50 10.0 1.4 69 2.50 5.5 1.1 68 3.00 6.2 1.3 67 2.75 6.0 1.2 66 2.50 5.8 1.2 20,2.5 1974 1.75 15.8 3.1 73 1.50 11.1 2.2 72 1.50 10.7 2.1 71 2.75 7.6 1.7 70 4.50 8.4 1.9 69 3.00 9.5 1.9 68 3.50 6.7 1.3 67 3.00 8.7 1.7 66 1.50 8.3 1.7 23.00 1974 1.50 20.1 4.0 73 1.25 18.2 3.6 72 1.25 18.2 3.6 71 2.50 10.8 2.1 70 3.50 9.6 1.9 69 2.00 9.9 2.0 68 2.00 10.5 2.2 67 2.00 8.0 1.5 66 2.50 3.0 0.6 18.50 1974 1.50 19.2 38.6 73 1.00 20.4 40.9 72 1.25 19.8 38.8 71 2.75 12.7 25.3 70 2.50 12.7 25.7 69 1.50 11.1 22.4 68 2.00 9.9 19.4 12.50 ....Continued 150 Core Area E Area F Area G Year deposited 1974 Depth i n t e r v a l LOI' 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 10T0" (mg C* g (cm) dry wtT 1974 2.20 115.0 73 2.00 111.0 72 2.50 187.1 71 2.00 124.5 70 3.00 177.5 69 3.50 98.5 68 1.00 175.6 67 1.00 103.1 16.20 1974 0.50 41.7 73 1.00 74.7 72 1.00 24.3 71 1.50 37.0 70 2.00 19.1 69 2.50 25.0 68 2.00 28.0 67 2.00 57.3 66 1.75 86.9 14.25 104.9 58.5 43.4 51.5 56.0 35.6 35.7 30.5 34.8 22.8 Percent LOI 22.9 22.2 37.4 25.0 35.4 19.7 35.1 20.6 8.3 14.9 4.9 7.5 3.8 5.1 5.8 11.3 17.3 20.9 11.7 8.6 10.3 11.2 7.1 7.1 6.1 6.8 4.6 mean of 6 samples from each layer annual layers not detected Appendix V. Seasonal changes i n species composition of microalgal associations. Numbers represent r e l a t i v e percent composition. Association A Melosira moniliformis M. nummuloides Synedra spp. Thalassionema sp. Navioula grevillei Rhizoclonium implexum Association B Navioula oanoellata Pleurosigma sp. Eantzsohia sp. Nitzehia sp. Association C Navioula grevillei Melosira nummuloides M. moniliformis Thalassionema sp. Synedra spp. Nitzsohia sp. Gomphonema sp. Aohnanthes sp. Ulothrix flaooa Jun 74 60 10 10 20 Dec 74 80 10 10 Dec 74 75 ko -1Y5 10 J u l 74 0 0 10 . 10 20 60 Jan"75 90 5 May 75 80 0 5 10 5 Feb 75 90 5 Jun 75 50 15 5 30 Mar 75 90 5 Jan 75 Feb 75 Mar 75 80 80 70 5 5 20 Apr 75 40 40 10 10 J u l 75 0 0 10 15 20 50 Apr 75 90 5 May 75 30 20 5 20 15 30 ....Continued Appendix V. Continued. Association D Havioula grevillei Navicula spp. Melosira moniliformis M. nummuloides Thalassionema sp. Synedra sp. Hantzschia sp. Pleurosigma aestaurii Association E Navicula cancellata N. grevillei Navicula spp. Melosira nummuloides M. moniliformis Melosira spp. Pleurosigma aestaurii Synedra tabulata Synedra sp. Pinnularia trevelyana Thalassionema sp. Nitzschia sp. Aohnanthes sp. Hantzschia sp. Licmorph&ravsv. Jan 75 }30 } 9 J-40 } 20 Feb 75 30 35 30 5 Mar.75 40 40 20 0 Apr 75 40 30 30 0 1974 1975 Jun J u l Aug Sep Oct Nov Dec Jan Feb 60 65 60 50 40 20 5 20 20 5 0 0 0 0 5 5 5 5 10 10 20 30 10 15 20 25 15 - 0 0 0 0 0 0 5 10 10 10 20 10 35 5 25 50 5 15 10 10 10 -10 5 20 hl5 15 10 •5 25 50 55 20 40 30 30 May Jun J u l Aug 70 75 70 75 5 5 0 0 15 10 10 10 0 0 0 0 0 0 0 0 10 10 20 15 ....Continued Appendix V. Continued. Association P 1974 1975 Jun J u l Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Vaucheria diohotoma 85 80 80 80 80 70 60 50 50 60 70 80 80 Phormidium sp. 5 5 5 5 0 0 0 0 0 0 0 5 5 Navioula sp. 5 10 10 10 b 0 0 0 0 10 10 10 10 Thalas8ionema sp. Synedra tabulata Pinnularia sp. Nitzschia sp. Diploneis sp. Rhizoclonium implexum Association G Ulothrix flaooa Synedra tabulata Navioula g r e v i l l e i Melosira sp. Licmorpharapsp. Achnanthee sp/ Thalassionema sp. Nitz8chia sp. 15 Nov 74 70 L30 5 20 300 40 50 50 30 20 Dec 74 70 30 Jan 75 60 40 Feb 75 70 30 Aug 80 5 10 Mar 75 80 20 Appendix VI. D i s t r i b u t i o n (coverage area) and biomass data for macroalgae and microalgal associations. Date 1974 6 June 21 June 5 July 19 July 11 August 27 August 2 September 13 September 30 October 22 November 18 December 1975 22 January 20 February 19 March 16 A p r i l 14 May 12 June 20 June 16 July 29 July 13 August 28 August Cladophora sp. E. minima -2 „ -2 -2 _ m gC«m m gC-m 150 8.74 160 « 180 9.21 200 3.74 400 10.74 250 20.12 400 11.92 250 24.83 400 9.00 200 20.28 400 7.12 200 20.12 180 6.12 200 13,42 150 5.31 200 — - — 200 9.90 — — 180 7.82 - - 160 3,75 _ 140 2.51 — — 120 1.88 — - 120 1.96 — — 120 1.48 110 2.92 130 2.72 150 5.72 150 3.30 150 6.18 180 — 400 7.19 250 18.42 420 10.30 280 17.10 480 8.89 220 18.12 400 8.12 200 18.49 2 E. p r o l i f e r a M. oxyspevmum -2 -2 -2 -2 m gC*m m gC»m 250 8.42 200 7.21 250 8.9.1 220 8.14 300 9.92 200 7.32 250 9.81 200 7.00 150 7.84 200 4.19 150 5.03 180 — 150 3.41 180 4.39 100 2.02 180 4.21 - - 120 3.98 - - 120 3.71 — - 120 3.00 — _ 125 1.50 50 1.92 120 2.72 50 7.74 180 3.94 50 9.31 220 7.17 150 11.39 220 7.92 150 14.92 250 9.04 200 17.31 250 9.00 250 14.72 220 8.92 200 12.00 200 7.10 150 12.11 200 5.21 100 9.31 200 4.99 • ...Continued Appendix VI. Continued. Date 1974 6 21 5 19 11 27: 2 13 30 22 18 1975 22 20 19 16 14 12 20 16 29 13 28 June June July July August Augiisifci, ; September September October November December January February March A p r i l May June June July July August August R. implexum gC«m m -2 -2 Spirogyra sp, -2 -2 m gC-m P. l i t t o r a l i s Association A m -2 gC •m~ m -2 gC •m -2 600 3.15 500 3.42 550 5.98 900 8.12 600 3.72 500 3.91 580 6.12 600 7.40 750 3.64 400 4.08 — — 280 -750 3.71 600 — - - 280 3.80 750 3.05 800 10.20 — - - -750 — 800 — — — - -600 2.00 800 5.90 - - - -600 2.72 600 5.27 - - - -400 1.50 400 2.09 - - - -- - - - 280 2.96 - -150 1.30 400 6.10 — — 300 1.61 — — 950 9.15 - -400 2.36 — - 1050 12.80 - -600 3.28 — - 1400 69.65 - -600 4.06 _ — 900 22.52 10001 5.32 650 — 600 3.43 500 6.88 500 7.83 650 3.10 600 — 400 5.00 500 7.60 700 3.52 500 3.94 — - 300 3.41 700 3.41 600 4.21 - - 4oo 3.98 800 3.10 850 11.72 - - - -800 2.74 900 12.00 - - - -....Continued Appendix VI. Continued. Date Association B Association C Association D Association E m"2 gC-m"2 -2 m gC-m"2 -2 m gC-m-2 -2 m gC-m" 1974 6 June - - - - - - 5000 0.75 21 June — — — — — — 5000 0.90 5 July — - - - - - 4000 0.86 19 July - - - - - - 4000 0.61 11 August - - - - - - 4500 27 August - - - - - - 4500 -2 September - - - - - - 8000 0.95 13 September - - - - - - 8000 0.90 30 October - - - - - - 100001 0.99 22 November — — — — — - 10100 1.07 18 December 320 0.74 180 1.01 - - 14500 1.14 1975 22 January 320 1.24 180 2.31 800 3.83 14500 1.78 20 February 425 3.92 210 2.21 1000 7.11 14500 1.76 19 March 220 2.18 160 1.36 1400 7.96 14000 1.59 16 A p r i l 110 0.81 160 1.41 1000 3.84 14000 2.17 14 May — - 140 0.62 - - 10000 1.94 12 June — - - - - - 5000 -20 June — - — — - - 5000 0.95 16 July - - - - - - 4000 0.74 29 July - - - - - - 4000 0.78 13 August - - - - - - 4500 0.59 28 August - - - - - - 4500 0.59 2 ....Continued Appendix VI. Continued Date 1974 6 June 21 June 5 July 19 July 11 August 27 August 2 September 13 September 30 October 22 November 18 December 1975 22 January 20 February 19 March 16 A p r i l 14 May 12 June 20 June 16 July 29 July 13 August 28 August Association F Association m"2 gC-m"2 m-2 gC-m" 750 4.98 750 4.71 - -750 - - -750 5.14 - -750 5.72 - -750 5.10 - -750 5.92 - -750 - - -750 4.01 - -750 3.98 90000 0.75 750 1.49 90000 1.99 750 1.20 90000 4.92 750 1.94 90000 17.42 750 2.41 90000 8.72 750 2.14 - -750 4.12 - -750 5.30 - -750 5.40 - -750 5.12 - -750 5.43 - -750 4.94 - -750 4.34 - -G 2 158 Appendix VII. Total biomas associations e Cu Ss is o O E Cu O tt o Ss E •XJ W tt • 4* K Date K> ft to to fe) E 1974 6 June 1.31 0.60 21 June 1.66 0.75 5 July 4.30 5.03 19 July 4.77 6.21 11 August 3.60 4.06 27 August 2.85 4.02 2 September 1.10 2.68 13 September 0.80 2.33 30 October - 1.98 22 November — 1.41 18 December — 0.60 1975 22 January - 0.35 20 February - 0.23 19 March — 0.24 16 A p r i l — 0.18 14 May 0.32 0.35 12 June 0.86 0.50 20 June 0.93 3.30 16 July 2.88 4.61 29 July 4.33 4.79 13 August 4.27 3.99 28 August 3.25 3.70 s for macroalgae and microalgal as kgC'distribution area" 1. o E Cu O E CO Ss e E 3 8 tt tt M O 5s o s O E Ss t~4 t*4 E ,<a is Ss t-4 3 3J O CK ca O H <3J Cfi Ss Ss *t» co Cu O Cfl O •«4 O O CO t« t-4 Ss O 44 44 Q 52 S> *t4 Cu •«4 • V-4 +4 52 Ss 5 H E Cu ft a>v &q Cu ft; v CQ CQ 2.11 1.44 1.89 1.71 3.29 2.22 1.79 2.23 1.96 3.55 2.93 1.46 2.73 1.63 -2.95 1.40 2.78 4.90 — 1.18 0.84 2.29 8.16 _ 0.75 0.86 1.74 1.44 -0.51 0.79 1.20 4.72 -0.20 0.73 1.63 2.16 — — 0.48 ,0.60 0.84 _ — 0.45 — — _ - 0.36 - - 0.83 _ 0.19 0.20 2.44 0.10 0.33 0.48 — 8.69 0.39 0.71 0.84 — 13.44 0.41 1.58 1.97 - 97.51 1.71 1.74 2.44 — 20.29 3.24 2.26 2.23 2.06 3.44 3.46 22255 2.02 2.01 2.00 3.68 1.96 2.46 1.97 — 2.40 1.42 2.39 2.53 — 1.82 1.04 2.48 9-96 — 0.93 1.00 2.19 10.80 -....Continued 159 Appendix VII. Continued. Date Association Total a l g a l A B C D E F G biomass-mo" 1974 6 June 7.31 - - - 3.75 3.74 27.14 21 June 4.44 - — — 4.50 3.53 26.63 5 July 2.75 — — — 3.44 3.69 28.06 19 July 1.06 - - - 2.94 3.86 30.87 11 August - — - — 2.75 4.24 27.13 27 August — — — - 4.58 3.83 20.07 2 September — - - — 7.60 4.44 23.05 13 September - - - - 7.20 3.72 18.78 30 October — — — - 9.90 3.01 16.80 22 November — — — — 10.70 2.99 67.50 83.04 18 December - 0.24 0.18 - 16.53 1.12 179.10 198.95 1975 22 J anuary - 0.40 0.42 3206 25.18 0.90 442.80 476.56 20 February — 1.67 0.46 7.H 25.52 1.46 1567.80 1613.84 19 March — 0.48 0.22 11.14 22.26 1.81 784.80 836.32 16 A p r i l — 0.09 0.23 3.84 30.38 1.61 138.78 14 May 5.32 — 0.09 - 19.40 3.09 54.73 12 June 3.91 — - 6.63 3.98 64.28 20 June 3.80 — — — 4.75 4.05 27.64 16 July 1.02 — - - 2.96 3.84 25.38 29 July 1.59 - - - 3.12 4.07 26.63 13 August — — — — 2.66 3.70 29.91 28 August - - - - 2.57 3.26 27.69 1 l6o Appendix VIII. Cladophora sp. Date IH C production and organic exudation data. (gCm~ 2«day~ 1) Enteromorpha minima Date Production Production * s = 15 cm below surface Exudation s* lm s* lm 1974 6 June 0.72 0.22 0.05 — 21 June 0.79 0.23 0.05 0.01 5 July 0.87 0.29 0.07 0.02 19 July 1.10 0.21 _ — 11 August 0.71 0.49 0.04 0.02 27 August 0.64 0.43 0.03 0.01 2 September 0.55 0.28 0.03 0.02 13 September 0.52 0.29 0.05 0.02 1975 14 May 0.52 0.32 0.04 0.01 12 June 0.49 0.13 0.04 0.01 20 June 0.68 0.14 0.08 0.01 16 July 0.77 0.18 0.08 _ 29 July 0.90 0.18 0.07 0.02 13 August 0.68 0.29 0.05 — 28 August 0.63 0.32 0.04 0.03 Exudation s lm s lm 1974 6 June 1.74 ' 0.63 0.10 0.02 21 June - 0.51 — 0.02 5 July 1.12 0.28 0.11 0.02 19 July 0.46 0.19 0.04 0.01 11 August 0.75 0.79 0.06 0.05 28 August 0.98 0.79 0.09 0.03 2 September 0.39 0.27 0.03 0.02 13 September 0.48 0.49 0.02 0.02 30 October 0.52 — 0.03 — 22 November 0.24 . 0.10 0.01 0.02 18 December — — _ 1975 22 January 0.12 0.09 0.01 — 20 February 0.47 0.30 0.03 0.02 19 March 0.51 — 0.04 — 16 A p r i l 0.69 0.52 0.05 0.03 14 May 0.74 0.51 — — 12 June 0.98 0.36 0.08 0.02 20 June 1.09 0.15 0.09 0.01 16 July 0.94 0.39 — — 29 July - - — — 13 August 0.66 0.31 0.05 0.02 28 August 0.41 0.39 0.03 0.02 .Continued 161 Appendix VIII. Continued Enteromorpha p r o l i f e r a Date 1974 6 June 21 June 5 July 19 July 11 August 27 August 2 September 13 September 1975 20 February 19 March 16 A p r i l 14 May 12 June 20 June 16 July 29 July 13 August 28 August Monostroma oxyspermum Date 1974 6 June 21 June 5 July 19 July 11 August 27 August 2 September 13 September 30 October 22 November 18 December 1975 22 January 20 February 19 March 16 A p r i l 14 May 12 June 20 June 16 July 29 July 13 August 28 August Production Exudation s lm s lm 0.46 0.10 0.04 0.01 0.76 0.11 0.07 -0.83 0.13 0.08 0.01 0.90 0.13 0.07 0.01 0.53 0.25 0.03 0.02 0.46 0.17 0.01 0.01 0.33 0.30 0.03 0.01 0.26 0.19 0.02 0.01 0.16 0.06 0.01 0.01 0.42 0.17 0.03 0.01 0.55 0.28 0.04 — 0.45 0.24 0.03 0.01 0.54 0.25 — 0.01 0.60 - 0.06 0.03 0.70 0.17 0.07 0.01 0.86 0.21 0.09 0.01 0.42 0.15 — 0.02 0.41 0.25 0.04 0.01 Production Exudation s lm s lm 0.92 0.10 0.08 0.01 1.22 0.16 0.09 0.02 0.74 0.11 0.05 0.02 0.99 - 0.07 -0.34 0.12 0.02 0.01 0.47 0.20 0.03 0.01 0.33 0.17 0.02 0.01 0.48 0.25 0.03 0.01 0.54 0.30 0.05 0.02 0.67 0.25 0.04 0.02 0.97 0.39 0.05 0.03 0.84 0.42 _ _ 1.99 0.91 0.10 0.07 2.43 0.90 0.3)2 0.08 1.74 0.90 0.09 0.07 1.43 - 0.05 -1.24 0.22 — — 0.91 0.14 0.07 0.02 0.90 0.17 0.08 0.02 0.54 0.15 0.05 0.02 0.52 0.20 0.04 0.02 0.37 0.17 0.03 0.01 . ...Continued 162 Appendix VIII. Continued. Rhizoclonium implexum Date Production Exudation s lm s lm 1972* 6 June 0.59 0.12 0.06 0.01 21 June 0.67 0.16 0.09 0.01 5 July 0.74 0.16 0.10 0.02 19 July 0.69 0.15 0.07 0.01 11 August 0.51 0.19 0.04 0.01 27 August 0.75 0.31 0.04 0.02 2 September 0.32 0.16 0.01 0.02 13 September 0.23 0.09 0.02 _ 30 October 0.11 0.06 0.01 mm 1975 22 J anuary 0.42 0.23 0.02 0.02 20 February 0.49 0.21 0.00 mm 19 March 0.63 0.20 _ 16 A p r i l 0.79 0.28 0.03 0.01 14 May 0.50 0.13 0.04 0.01 12 June 0.43 0.10 0.07 0.02 20 June 0.48 0.10 0.04 mm 16 July 0.75 0.19 0.13 0.02 29 July 0.76 0.16 0.11 0.02 13 August 0.58 0.18 0.04 0.01 28 August 0.69 0.17 0.05 0.01 Spirogyva sp. Date Production Exudation s lm s lm 1974 6 June _ _ mm 21 June 2.13 0.43 0.54 0.16 5 July 2.04 — 0.46 _ 19 July 1.49 0.32 — 0.02 11 August 1.12 0.27 0.17 0.03 27 August 1.34 0.21 0.20 _ 2 September 0.93 0.27 0.09 0.02 13 September 1.14 0.25 0.11 0.04 30 October 0.26 0.10 0.04 0.02 1975 12 June 1.74 0.37 0.30 0.06 20 June 1.39 0.24 0.22 _ 16 July 1.90 0.30 0.28 0.11 29 July 1.62 0.23 0.29 0.10 13 August 1.07 0.62 0.12 0.07 28 August 0.92 0.47 0.16 0.04 .Continued 163 Appendix VIII. Continued • "Pylaiella l i t t o r a l i s Date Production Exudation s lm s lm 1974 6 June 0.23 0.08 0.10 0.01 21 June 0.22 0.04 0.07 — 18 December 0,24 — — — 1975 22 January 0.36 0.13 0.10 0.01 20 February 0.65 0.32 0.11 0.01 19 March 1.72 0.65 0.31 0.02 16 A p r i l 1.07 0.61 0.17 0.02 14 May 1.29 0.48 — — 12 June 0.24 0.07 0.09 0.01 20 June 0.17 0.04 0.06 -Association A Date Production Exudation s lm s lm 1974 6 June 1.00 0.22 0.24 0.01 19 June 0.64 0.22 0.18 0.01 5 July O.38 0.08 0.09 0.02 19 July 0.31 0.04 0.10 — 1975 14 May 0.84 0.36 0.09 0.02 12 June 1.21 0.35 0.22 0.02 20 June 1.04 — 0.20 — 16 July 0.46 0.14 0.38 — 29 July 1.13 0.20 0.30 0.01 Association B Date Production Exudation s lm s lm 1974 18 December 0.08 0.04 0.04 0.01 1975 22 January 0.16 0.08 0.04 0.01 20 February 0.12 0.05 - -19 March 0.09 0.02 0.01 0.00 16 A p r i l 0.11 0.05 0.02 0.01 ....Continued 164 Appendix VIII. Continued. Association C Date Production Exudation s lm s lm 1974 0.06 18 December 0.29 0.17 0.02 1975 22-January 0.37 0.29 0.08 0.02 20 February 0.27 0.14 0.04 0.01 19 March 0.24 0.15 0.01 0.00 16 A p r i l 0.17 0.10 - -14 May 0.12 0.07 0.02 — Association D Date Production Exudation s lm s lm 1975 22 January 0.58 0.34 0.10 0.02 20 February 0.65 0.33 0.09 0.02 19 March 0.37 0.14 0.03 0.01 16 A p r i l 0.21 - 0.04 — Association E Date Production Exudation s 31m s lm 1974 6 June 0.31 0.05 0.05 -21 June 0.21 0.05 0.07 0.01 5 July 0.29 0.06 0.06 0.01 19 July 0.32 0.07 0.08 -11 August 0.41 0.16 0.06 0.02 27 August 0.30 0.21 0.04 0.01 2 September 0.39 0.21 - -13 September 0.47 0.23 0.07 0.01 30 October 0.24 0.17 0.02 0.01 22 November 0.11 0.08 0.01 0.01 18 December 0.02 - - -1975 22 January 0.16 0.09 0.03 0.01 20 February 0.17 0.07 0.03 0.01 19 March 0.39 0.11 - -16 A p r i l 0.47 0.23 0.06 0.01 14 May 0.55 0.33 0.04 0.02 12 June 0.51 0.11 - -20 June 0.49 0.14 0.09 0.02 16 July 0.31 0.12 0.08 0.01 29 July 0.30 0.04 0.08 0.01 13 August 0.29 0.11 - 0.02 28 August 0.27 0.19 0.06 0.02 . ...Continued 165 Appendix VIII. Continued. Association P Date 1974 5 June 21 June 5 July 19 July 11 August 27 August 2 September 13 September 30 October 22 November 18 December 1975 22 January 20 February 19 March 16 A p r i l 14 May 12 June 20 June 11 July 29 July 13 August 28 August Production s lm 0.84 0.14 0.91 0.13 0.62 0.17 0.76 0.15 0.59 0.23 0.40 0.23 0.48 0.25 0.23 0.11 0.14 0.09 0.11 0.02 0.28 0.14 0.59 0.22 0.68 0.31 0.57 0.13 0.59 0.16 0.54 0.10 0.50 0.12 0.41 0.14 Exudation s lm 0.19 0.17 0.02 0.14 0.02 0.13 0.02 0.05 0.01 0.02 0.02 0.02 0.02 0.02 0.01 0.02 0.01 0.00 0.06 0.01 0.05 0.02 0.06 0.02 0.16 0.02 0.19 0.02 0.12 0.02 0.14 0.02 0.03 0.01 Association G Date 1974 22 November 18 December 1975 22 January 20 February 19 March Production s lm 0 .30 0.19 0 .15 0.05 0 .11 0.09 0 .17 0.13 0 .09 -Exudation s lm 0.01 0.01 0.01 0.01 0.01 0.01 0.01 166 Appendix IX, Estimated monthly percent emersion (exposed) and immersion (covered) time for the Squamish delta as determined from tid e tables. Month Covered Exposed 1974 1975 June July August September October November December > January February March A p r i l May June July August 25 25 50 75 75 84 84 84 84 50 75 50 25 25 50 75 75 50 25 25 16 16 16 16 50 25 50 75 75 50 167 Appendix X. Turnover times for major producers based on average biomass and primary production values. Time Time (days) (days) Cladophora sp. 17 Association A 8 Enteromorpha minima 20 Association B 21 E. p r o l i f e r a 24 Association C 8 Monostroma oxyspermum 8 Association D 17 Rhizoolonium implexum 6 Association E 4 Spirogyra Sp. 9 Association P 15 P y . l a i e l l a l i t t o r a l i s 40 Association G 48 168 Appendix XI. Annual net primary production estimates for ct Carex l y n g b y e i based on growth increments . Biomass g organic-m" Growth increment _2 g organic.m 1974 29 March 32.8 28 A p r i l 92.8 28 May 391.0 19 June 475.6 5 July 831.4 30 July 1023.8 18 August 1095.7 18 September 466.5 32.8 60.0 298.2 84.6 355.8 192.4 71.9 negative 1Q95.7 -2 -1 Above ground net production = 1095.7 g organic•m -season b -2 -1 Below ground net production = 971.7 g organicm" 'season" Total net production -2 -1 = 2067.4 g organic-m -season a a f t e r Levings and Moody (1976) using harvest method of Milner and Hughes (1968) b assuming below ground production i s 47% of t o t a l net production (Yamanaka 1975) Appendix XII. Net energy production for major a l g a l producers. Pro-rated values represent percent of t o t a l for each month (calculations based on data from Table 11). co Q 3 o s: to 03 Oj •* a H o 3 a* • » «s: a t3 «». • Cu CC) CO o M o a hi CO «> o o tJ R O H O o B cj «a a* cc 2 h! K <c O O 3 Q 3 O •3 »S a hs S 3 a a a 3 a a* a* K 1974 a a 3 September 1.7 2.7 0.6 1.5 4.5 9.5 October - 3.1 - 3.2 2.1 3.3 November - 0.3 - 0.2 - -December - 0.1 - 0.4 - -1975 January - 0.06 - 0.05 0.02 -February - 0.2 0.02 0.6 0.3 -March - 0022 0.08 1.6 1.0 -A p r i l - 0099 0.3 4.0 2.8 -May 1.9 1.7 1.2 5.2 5.2 -June 1.5 1.4 1.8 4.4 5.5 16.5 July 4.3 4.8 3.9 4.3 12.4 23.2 August 5.7 3.9 1.8 2.5 12.5 26.4 ct- a o v*. hj co a <r-* Association CO* A B c D E F 6 - - - - - 74.3 5.2 -- - - - - 85.1 3.1 -- - - - - 8.1 0.3 91.0 0.4 - 0.1 0.03 - 12.1 0.6 86.2 0.4 _ 0.2 0.04 1.7 30.5 0.6 65.6 2.1 - 0.2 0.02 2.1 27.0 0.6 66.8 8.0 - 0.1 0.02 2.6 22.9 1.6 61.7 18.3 - 0.1 0.03 2.2 67.2 4.0 -21.6 12.5 - 0.02 - 42.1 8.6 -3.1 11.4 - - - 45.2 9.2 -- 10.3 - - - 22.6 11.1 -— — — — — 40.1 7.1 — 170 Appendix XIII. Net energy production of major a l g a l producers. Pro-rated values represent percent d i s t r i b u t i o n over the growth period. (Calculations based on data from Table 11.) tt « E 3 Cu O E CO SH ts tt E 3 C a tt *ti o O O ts O E O E ts E E .« is ts 3 s> t-4 « o tt O *K O H o» Q> ts o E ts to Cu O <a o M O <» «t» O to ts tt tt • K o K SO r-i +» 1974 52 •*» C ts O H »«: E cu a Cj to b l E 2s o to to Fti r4 September 8.0 10.6 4.5 2.9 7.2 10.3 -October - 9.9 - 5.1 2.7 2.9 -November 5.2 - 2.0 - - -December - 1.4 - 2.4 - - 0.8 1975 January - 0.9 - 3.5 1.1 - 1.1 February - 3.3 1.0 6.3 2.1 - 8.5 March - 5.1 3.2 16.8 8.2 - 31.9 A p r i l - 7.2 5.2 15.8 8.9 - 28.1 May 14.1 10.3 13.4 15.8 12.7 - 25.7 June 11.7 8.9 21.7 14.4 14.4 29.5 3.8 July 40.9 22.7 36.2 10.3 23.8 30.4 -August 25.3 14.4 14.4 4.7 18.7 26.9 -....Continued 171 Appendix XIII. Continued. Association 1975 [ A B c D E F G September - - - - 8.0 6.3 -October - - - - 7.5 3.1 -November - - - - 4.0 1.9 26.9 December - 11.2 15.5 - 3.8 2.1 15.7 January — 29.4 28.3 11.7 2.7 14.8 February - 31.8 17.6 31.5 15.3 4.4 22.2 March - 19.4 20.7 38.7 12.9 10.2 20.4 A p r i l - 8.1 10.9 12.4 14.6 9.9 -May 38.4 - 7.2 - 7.1 16.3 -June 36.9 - - - 8.1 18.5 -July 24.7 - - - 3.0 16.5 -August - - - - 4.1 8.1 — 172 Appendix XIV. Primary production and photosynthetic e f f i c i e n c y data for constructing seasonal energy flow pathways. P a l l (September) Gross Respiration Net Production P/Sc a b Production Dis. Part. Cladophora 103. .78 22, .83 5. .26 75. .69 0, .17 sp. Enteromorpha 55. .84 13. .74 2. .53 39. .57 0, .09 minima Enteromorpha 148, .80 38, .98 7-.14 102, .68 0, .24 p r o l i f e r a .85 Monostroma 72, 10. .13 5. .02 57. .70 0, .13 oxyspermum Rhizoclonium 80, .98 17. .64 5. .07 58, .26 0, .13 implexum Spirogyra 151. .94 53. .63 13. .76 84, .55 0, .21 sp. P y l a i e l l a l i t t o r a l i s Association A t\ Association B Association ri 0 Association D Association E Association •ct 143. .64 38. .78 13. .63 91. .23 0, .22 70, .50 21, .15 5. .42 43. .93 0, .10 Association G a Dis. = dissolved organic exudation b Part. = pa r t i c u l a t e organic c P/S = photosynthetic e f f i c i e n c y ....Continued 173 Appendix XIV. Continued. Winter (December) Gross Respiration Net Production P/S° Production D i s . a P a r t . b Cladophora sp. Enterqmorpha 26.63 6.55 1.20 18 ,88 0.22 minima Enteromorpha p r o l i f e r a Monoetroma 92.74 12.89 5.98 73 .87 0.89 oxyspermum Rhizoolonium _ _ _ implexum Spirogyra sp. P y l a i e l l a l i t t o r a l i s Association A 45.45 14.14 4.51 26 .62 0.35 Association B Association n 13.14 3.40 1.75 . 7 .99 0.11 6.47 1.85 0.49 4 .13 0.05 O Association - - - _ -V Association E Association 37.21 7.05 3.53 . .26 .63 .0.34 24.01 7.20 1.85 14 .95 0.19 r Association G 23.58 4.20 1.55 17 .83 0.22 a Dis. = dissolved organic exudation Part. = pa r t i c u l a t e organic 0 P/S = photosynthetic e f f i c i e n c y .Continued 174 Appendix XIV. Continued. Spring (March) Gross Respiration Net Production P/S° Production D i s . a P a r t . b Cladophora sp. Enteromorpha 125. .11 . 30 .78 5, .66 88 .67 1. .16 minima Enteromorpha . 94, .78 24 .83 . 4, .58 . 65 .37 0, .86 p r o l i f e r a 428, .68 341 Monostroma .56 59 .57 27, .31 4, .56 oxyspermum 108 Rhizoolonium 140, .11 30 .54 8, .76 781 1. .35 implexum Spirogyra sp. P y l a i e l l a l i t t o r a l i s 489, .42 172 .17 48, .61, 286 .64 3, .92 Association A A Association B Association n 33. .18 8 .59 4, .42 20 .17 ,0, .30 9. .93 22, 884 0, .74 6 .35 , 0, .09 Association D Association V 116, .50 25 .00 8, .81, 82 .69 1, .13 131, .47 35 .50 12, .47 83 .50 1, .18 Association TP 114, .99 34 .50 8, .85 71 .64 0, .99 r Association G 30, .61 5 .45 2, .01 23 .15 0, .31 a Dis. = dissolved organic exudation Part. = p a r t i c u l a t e organic c P/S = photosynthetic e f f i c i e n c y .Continued 175 Appendix XIV. Continued. Summer (June) Gross Respiration Net Production P/Sc a b Production Dis. Part. Cladophora 166 •15 36 .55 8. 42 121. ,18 0 .16 sp. .67 .28 .16 Enteromorpha 159 39 7. 23 113. 0 .15 minima Enteromorpha 183 .13 48 .46 8. 80 126. .35 0 .17 p v o l i f e r a 36 .64 Monostroma 263 .61 17. 02 209- .95 0 .29 oxy8permum .86 .89 44 108. .15. Rhizoclonium 150 32 9. .53 0 implexum Spirogyra 281, .41 505 .69 178 .51 45. 81 .37 0 sp. 81, P y l a i e l l a 138 .73 43 .70 13. 77 .26 0 .01 l i t t o r a l i s Association A 439' M 117 v62 43-. •22 289. ,30 0 .42 i l Association B Association r> Association D Association E Association G 230 .09 62 .12 21. 84 146, .13 0 .21 208 .13 62 .44 166 021 129 .67 0 .18 a Dis. = dissolved organic exudation b Part. = p a r t i c u l a t e organic c P/S = photosynthetic e f f i c i e n c y 

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