Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Rubidium and cesium as indicators of diet in freshwater fish with particular emphasis on overlap in diet.. 1986

You don't seem to have a PDF reader installed, try download the pdf

Item Metadata

Download

Media
UBC_1986_A1 C54.pdf [ 6.7MB ]
Metadata
JSON: 1.0097183.json
JSON-LD: 1.0097183+ld.json
RDF/XML (Pretty): 1.0097183.xml
RDF/JSON: 1.0097183+rdf.json
Turtle: 1.0097183+rdf-turtle.txt
N-Triples: 1.0097183+rdf-ntriples.txt
Citation
1.0097183.ris

Full Text

RUBIDIUM AND CESIUM AS INDICATORS OF DIET IN FRESHWATER FISH WITH PARTICULAR EMPHASIS ON OVERLAP IN DIET BETWEEN JUVENILE SOCKEYE SALMON (ONCORHYNCHUS NERKA), AND THREESPINE STICKLEBACK (GASTEROSTEUS ACULEATUS) by ALYRE CHIASSON M.Sc, U n i v e r s i t y Of Manitoba, 1980 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSPHY in THE FACULTY OF GRADUATE STUDIES (Department of Zoology) We accept t h i s t h e s i s as conforming to the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA 3 October 1986 © A l y r e Chiasson, 1986 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study. I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the head o f my department or by h i s o r her r e p r e s e n t a t i v e s . I t i s understood t h a t copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be allowed without my w r i t t e n p e r m i s s i o n . Department of A ^ - i J U r P y ^ The U n i v e r s i t y of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date g>Jb. \H / fob DE-6 (3/81) i i ABSTRACT Body burdens of rubidium and cesium were used to assess o v e r l a p i n d i e t s of sockeye salmon (Oncorhynchus nerka) and t h r e e s p i n e s t i c k l e b a c k (Gasterosteus a c u l e a t u s ) i n Kennedy, C u l t u s , and Great C e n t r a l Lakes, B r i t i s h Columbia and Lake Al e k n a g i k , A l a s k a , lakes i n which co m p e t i t i o n between sockeye salmon and t h r e e s p i n e s t i c k l e b a c k has been suggested. D i f f e r e n c e s i n uptake p a t t e r n s of Cs i n j u v e n i l e . coho (Oncorhynchus k i s u t c h ) and t h r e e s p i n e s t i c k l e b a c k were a t t r i b u t a b l e to d i f f e r e n c e s i n d i e t and not p h y s i o l o g y . T i s s u e c o n c e n t r a t i o n s of Rb and Cs were examined i n t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye h e l d i n wire cages i n both the l i t t o r a l and l i m n e t i c zones of Kennedy Lake. C o n c e n t r a t i o n s of Rb were dependent on type of s u b s t r a t e over which f i s h had f e d . When s i g n i f i c a n t d i f f e r e n c e s i n c o n c e n t r a t i o n s were d e t e c t e d , h i g h e r c o n c e n t r a t i o n s were a s s o c i a t e d with the l i t t o r a l zone. In l a t e May, Cs c o n c e n t r a t i o n i n f i s h c a ptured o f f s h o r e were higher i n t h r e e s p i n e s t i c k l e b a c k than i n j u v e n i l e sockeye but not i n June or J u l y . N e i t h e r s p e c i e s t r a c k e d Rb and Cs c o n c e n t r a t i o n s i n zooplankton. In Kennedy, C u l t u s , Great C e n t r a l , and Lake Aleknagik, h i g h e r c o n c e n t r a t i o n s of Cs were found i n t h r e e s p i n e s t i c k l e b a c k c a p t u r e d onshore than i n j u v e n i l e sockeye c a p t u r e d o f f s h o r e . In Enos Lake, were there are two v a r i e t i e s of s t i c k l e b a c k s , rubidium c o n c e n t r a t i o n s appeared to be m o d i f i e d by f e e d i n g over d i f f e r e n t s u b s t r a t e s . In a comparison of squawfish ( P t y c h o c h e i l u s o r e q o n e n s i s ) , r e d s i d e s h i n e r s ( R i c h a r d s o n i u s b a l t e a t u s ) , c o t t i d s (Cottus a s p e r ) , and peamouth chub ( M y l o c h e i l u s c a u r i n u s ) , from C u l t u s Lake, higher c o n c e n t r a t i o n s of Cs were observed i n squawfish, i n agreement with higher c o n c e n t r a t i o n s of Cs r e p o r t e d i n p i s c i v o r e s . I t was concluded that Rb and Cs c o n c e n t r a t i o n s may r e f l e c t the extent to which sockeye, s t i c k l e b a c k or other s p e c i e s have been f e e d i n g onshore or o f f s h o r e but does not p r o v i d e a r e a d i l y q u a n t i f i e d measure of the degree of o v e r l a p i n d i e t . Present understanding of Rb and Cs i n both f i s h and t h e i r prey i s i n s u f f i c i e n t f o r use of t h i s technique to assess s i m i l a r i t y i n d i e t . The method would appear best s u i t e d f o r small l a k e s with few s p e c i e s . TABLE OF CONTENTS ABSTRACT i i LIST OF TABLES v i LIST OF FIGURES v i i i ACKNOWLEDGEMENTS X Chapter 1 1 General d e s c r i p t i o n 1 I n t r o d u c t i o n 1 Study area 8 M a t e r i a l s and methods 12 Sample c o l l e c t i o n 12 Contamination d u r i n g c o l l e c t i o n 12 Instrumentation and a n a l y s i s 14 Water 15 Zooplankton 16 F i s h 17 C o r r e c t i o n f o r i n t e r f e r e n c e e f f e c t s 17 Data A n a l y s i s 18 Chapter 2 19 Uptake of Cs by coho and t h r e e s p i n e s t i c k l e b a c k 19 I n t r o d u c t i o n 19 M a t e r i a l s and methods 24 R e s u l t s 27 D i s c u s s i o n 34 Chapter 3 38 T r a n s f e r experiments, r o l e of sediments 38 I n t r o d u c t i o n 38 M a t e r i a l s and methods 41 Short-term experiment: t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye 41 Long-term experiment: t h r e e s p i n e s t i c k l e b a c k .. 44 R e s u l t s 46 Short-term experiments: t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye 46 Long-term: t h r e e s p i n e s t i c k l e b a c k 52 D i s c u s s i o n : short-term and long-term experiments .... 59 Chapter 4 63 Int e r a n n u a l v a r i a t i o n i n Rb and Cs c o n c e n t r a t i o n s i n water, zooplankton, and f i s h 63 I n t r o d u c t i o n 63 M a t e r i a l s and methods 67 R e s u l t s 72 Water 72 Zooplankton 77 F i s h 82 D i s c u s s i o n 93 Chapter 5 99 D i e t h i s t o r y and c o m p e t i t i o n as indexed by rubidium and cesium 99 I n t r o d u c t i o n 99 M a t e r i a l s and methods 106 Se c t i o n 1: Sympatric s t i c k l e b a c k s ( E n o s Lake) ..106 V R e s u l t s 107 D i s c u s s i o n 113 M a t e r i a l s and methods ....115 S e c t i o n 2: J u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k 115 R e s u l t s 116 D i s c u s s i o n 145 M a t e r i a l s and methods 150 S e c t i o n 3: C o t t i d s , peamouth chub, r e d s i d e s h i n e r s and squawfish 150 R e s u l t s 151 D i s c u s s i o n 162 General d i s c u s s i o n ;....164 References 169 Appendix I 179 Parameter s e t t i n g s f o r measurement of Rb and Cs 179 Appendix II 180 I n t e r f e r e n c e i n measurement of Rb and Cs 180 M a t e r i a l s and methods 180 R e s u l t s 180 I o n i z a t i o n i n t e r f e r e n c e 183 M a t e r i a l s and methods 183 R e s u l t s 184 R e c a l i b r a t i o n curves 184 M a t e r i a l s and methods 184 R e s u l t s 191 LIST OF TABLES Table 1. S a l i e n t morphometric data f o r la k e s sampled ... 9 Table 2. Record of f i s h captured i n v a r i o u s l a k e s 10 Table 3. Lakes and items assessed f o r Rb and Cs content 13 Table 4. C o n c e n t r a t i o n of Cs i n the stomach c o n t e n t s of coho and t h r e e s p i n e s t i c k l e b a c k 33 Table 5. M u l t i p l e comparisons f o r Rb and Cs c o n c e n t r a t i o n s i n sockeye and t h r e e s p i n e s t i c k l e b a c k h e l d onshore and o f f s h o r e , short-term experiment .... 51 Table 6. C o n c e n t r a t i o n s of Rb and Cs i n stomach c o n t e n t s of j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k h e l d onshore and o f f s h o r e 53 Table 7. Nonparametric m u l t i p l e comparisons of Rb c o n c e n t r a t i o n s i n t h r e e s p i n e s t i c k l e b a c k from l o n g - term h o l d i n g experiment 56 Table 8. Nonparametric m u l t i p l e comparisons of Cs c o n c e n t r a t i o n s i n t h r e e s p i n e s t i c k l e b a c k from l o g - term h o l d i n g experiment 58 Table 9. C o n c e n t r a t i o n of Rb and Cs i n stomach c o n t e n t s of j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k captured from Kennedy Lake d u r i n g e a r l y s p r i n g and e a r l y summer 1983 . 92 Table 10. C o n c e n t r a t i o n s of Rb and Cs i n the stomach contents of s t i c k l e b a c k s from Enos Lake 112 Table 11. T o t a l l e n g t h s of 1 yr and 2 yr sockeye migrants r e p o r t e d by F o e r s t e r (1929) f o r C u l t u s Lake, compared with sockeye captured from C u l t u s Lake on May 15th, 1985 123 Table 12. Nonparametric m u l t i p l e comparisons among c o n c e n t r a t i o n s of Rb and Cs i n Kennedy sockeye smolts, Babine.sockeye smolts, and 1+ sockeye from C u l t u s Lake 125 Table 13. Nonparametric m u l t i p l e comparisons f o r Rb c o n c e n t r a t i o n s i n t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye from Kennedy, C u l t u s , Kennedy, Great C e n t r a l and Lake Aleknagik 142 Table 14. Nonparametric m u l t i p l e comparisons f o r Cs c o n c e n t r a t i o n s among Kennedy, C u l t u s , Kennedy, Great C e n t r a l and Lake Aleknagik 143 Table 15. D i f f e r e n c e between rank means f o r j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k w i t h i n l a k e s 144 Table 16. Nonparametric m u l t i p l e comparisons f o r Rb c o n c e n t r a t i o n s i n C u l t u s Lake peamouth chub, c o t t i d s , squawfish, and r e d s i d e s h i n e r s , and i n Kennedy Lake peamouth chub and c o t t i d s 160 Table 17. Nonparametric m u l t i p l e comparisons f o r Cs c o n c e n t r a t i o n s i n C u l t u s Lake peamouth chub, c o t t i d s , squawfish, and r e d s i d e s h i n e r s , and i n Kennedy Lake peamouth chub and c o t t i d s 161 Table 18. Composition of a r t i f i c i a l zooplankton matrix .189 Table 19. Composition of a r t i f i c i a l f i s h matrix 190 Table 20. C o n s t r u c t i o n of r e c a l i b r a t i o n curves 192 Table 21. L i s t of c o e f f i c i e n t s f o r r e c a l i b r a t i o n c u r ves 203 v i i i LIST OF FIGURES F i g u r e 1. C o n c e n t r a t i o n of Cs i n coho and t h r e e s p i n e s t i c k l e b a c k 28 F i g u r e 2. Wet weight of stomach contents i n coho and t h r e e s p i n e s t i c k l e b a c k 30 F i g u r e 3. Map of Kennedy Lake 42 F i g u r e 4.. C o n c e n t r a t i o n s of Rb i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k h e l d o f f s h o r e and onshore, s h o r t - t e r m experiment 47 F i g u r e 5. C o n c e n t r a t i o n s of Cs i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k h e l d o f f s h o r e and onshore, shor t - t e r m experiment 49 F i g u r e 6. C o n c e n t r a t i o n s of Rb and Cs i n t h r e e s p i n e s t i c k l e b a c k h e l d over v a r i o u s substate types 54 F i g u r e 7. Map of Great C e n t r a l Lake 68 F i g u r e 8. Map of Kennedy Lake 70 F i g u r e 9. C o n c e n t r a t i o n s of Rb and Cs i n water samples from Kennedy and Great C e n t r a l Lake 73 F i g u r e 10. Median and q u a r t i l e p l o t s f o r Cs and Rb i n water samples from Kennedy and Great C e n t r a l Lake ... 75 F i g u r e 11. C o n c e n t r a t i o n s of Rb and Cs i n zooplankton from Kennedy and Great C e n t r a l Lake 78 F i g u r e 12. Median and q u a r t i l e p l o t s of Rb and Cs c o n c e n t r a t i o n s i n zooplankton 80 F i g u r e 13. C o n c e n t r a t i o n s of Rb i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k captured i n Kennedy Lake d u r i n g s p r i n g and e a r l y summer 1983 83 F i g u r e 14. C o n c e n t r a t i o n s of Cs i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k c aptured i n Kennedy Lake d u r i n g s p r i n g and e a r l y summer 1983 85 F i g u r e 15. Median and q u a r t i l e p l o t s of Rb c o n c e n t r a t i o n s i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k c aptured i n Kennedy Lake d u r i n g e a r l y s p r i n g and e a r l y summer 1983 87 F i g u r e 16. Median and q u a r t i l e p l o t s of Cs c o n c e n t r a t i o n s i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k c a p t u r e d i n Kennedy Lake d u r i n g e a r l y s p r i n g and e a r l y summer 1983 89 F i g u r e 17. C o n c e n t r a t i o n s of Rb i n Enos Lake s t i c k l e b a c k s ...108 F i g u r e 18. C o n c e n t r a t i o n s of Cs i n Enos Lake s t i c k l e b a c k s 110 F i g u r e 19. C o n c e n t r a t i o n s of Rb i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k captured from Kennedy and C u l t u s Lake i n the s p r i n g of 1985 117 F i g u r e 20. C o n c e n t r a t i o n s of and Cs i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k captured from Kennedy and C u l t u s Lake i n the s p r i n g of 1985 119 F i g u r e 21. C o n c e n t r a t i o n s of Rb and Cs i n sockeye smolts c a p t u r e d from Kennedy and Babine Lake i n the s p r i n g of 1985 121 F i g u r e 22. Median and q u a r t i l e p l o t s of t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye c a p t u r e d from Kennedy and C u l t u s Lake i n the s p r i n g of 1 985 126 F i g u r e 23. C o n c e n t r a t i o n s of Rb i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Lake Aleknagik 129 F i g u r e 24. C o n c e n t r a t i o n s of Cs i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Lake Aleknagik ....131 F i g u r e 25. C o n c e n t r a t i o n s of Rb i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k captured from Kennedy, C u l t u s , Great C e n t r a l , and Lake Aleknagik 134 F i g u r e 26. Median and q u a r t i l e p l o t s of Rb i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k c a p t u r e d from Kennedy, C u l t u s , Great C e n t r a l , and Lake Aleknagik ..136 F i g u r e 27. C o n c e n t r a t i o n s of Cs i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k captured from Kennedy, C u l t u s , Great C e n t r a l , and Lake Aleknagik 138 F i g u r e 28. Median and q u a r t i l e p l o t s of Cs i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k c a p t u r e d from Kennedy, C u l t u s , Great C e n t r a l , and Lake Aleknagik ..140 F i g u r e 29. C o n c e n t r a t i o n s of Rb i n C u l t u s Lake peamouth chub, c o t t i d s , squawfish, and r e d s i d e s h i n e r s , and i n Kennedy Lake peamouth chub and c o t t i d s 152 F i g u r e 30. C o n c e n t r a t i o n s of Cs i n C u l t u s Lake peamouth chub, c o t t i d s , squawfish, and r e d s i d e s h i n e r s , and i n Kennedy Lake peamouth chub and c o t t i d s 154 F i g u r e 31. C o n c e n t r a t i o n s of Rb and Cs i n C u l t u s Lake peamouth chub, with expanded s c a l e to show r e l a t i o n s h i p with dry weight 156 F i g u r e 32. Median and q u a r t i l e p l o t s of Rb and Cs c o n c e n t r a t i o n s i n C u l t u s Lake peamouth chub, c o t t i d s , squawfish, and r e d s i d e s h i n e r s , and i n Kennedy Lake peamouth chub and c o t t i d s 158 F i g u r e 33. Change in measured c o n c e n t r a t i o n of Rb i n f i s h with i n c r e a s e i n d i l u t i o n 181 F i g u r e 34. Standard curve f o r Rb, alone and s p i k e d with 1 000 ppm NaCl 185 F i g u r e 35. Standard curve f o r Cs, alone and s p i k e d with 1000 ppm NaCl 187 F i g u r e 36. R e c a l i b r a t i o n curves f o r Rb i n zooplankton ..193 F i g u r e 37. R e c a l i b r a t i o n curves f o r Cs i n zooplankton ..195 F i g u r e 38. R e c a l i b r a t i o n curves f o r Rb i n f i s h 197 F i g u r e 39. R e c a l i b r a t i o n curves f o r Cs i n f i s h 199 F i g u r e 40. P r e d i c t e d versus observed absorbances f o r Rb- zooplankton r e c a l i b r a t i o n curves 204 F i g u r e 41. P r e d i c t e d versus observed absorbances f o r Cs- zooplankton r e c a l i b r a t i o n curves 206 F i g u r e 42. P r e d i c t e d versus observed absorbances f o r Rb- f i s h r e c a l i b r a t i o n curves 208 F i g u r e 43. P r e d i c t e d versus observed absorbances f o r Cs- f i s h r e c a l i b r a t i o n curves 210 X ACKNOWLEGEMENTS My s i n c e r e thanks to my s u p e r v i s o r Dr. L a r k i n , f o r h i s i n s i g h t s and encouragement d u r i n g the course of t h i s t h e i s i s . In a d d i t i o n , I would l i k e to thank my committee members, Dr. K. H a l l , Dr. K. Hyatt, Dr. D. McP h a i l , and Dr. T. Northcote. A s p e c i a l commendation goes to Stanya Horsky f o r her superb e f f o r t s i n d e a l i n g with the a n a l y t i c a l a psects of t h i s study. In a d d i t i o n , many thanks to my wife I n g r i d who waited p a t i e n t l y i while t h i s t h e s i s was being completed. I would a l s o l i k e to thank the N a t u r a l Sciences and E n g i n e e r i n g Research C o u n c i l of Canada t h a t p r o v i d e d funding f o r t h i s p r o j e c t . 1 CHAPTER 1 General d e s c r i p t i o n I n t r o d u c t i o n The f e e d i n g h a b i t s of f i s h c o n s t i t u t e s an a c t i v e area of res e a r c h , not only to those seeking to understand the i n t e r r e l a t i o n s h i p s among or w i t h i n s p e c i e s but a l s o f o r f i s h e r i e s managers concerned with f a c t o r s that a f f e c t p o p u l a t i o n dynamics. A degree of complexity i s inherent i n such a statement, as f e e d i n g h a b i t s vary s p a t i a l l y i n response to prey and c o m p e t i t o r s , and t e m p o r a r i l y i n response t o age of f i s h and annual and se a s o n a l abundances i n a v a i l a b i l i t y of prey ( N i l s s o n 1958). R e g a r d l e s s , f i e l d s t u d i e s have g e n e r a l l y i n d i c a t e d that f o r each s p e c i e s of f i s h the p a t t e r n of food e x p l o i t a t i o n i s u s u a l l y unique (Hyatt 1979). How unique, has been a frequent q u e s t i o n , u s u a l l y addressed i n s t u d i e s examining c o m p e t i t i o n f o r food (Rogers 1968, Markovstev 1973). The l a t t e r aspect has been c i t e d as perhaps one of the most important f a c t o r s determining and r e g u l a t i n g community s t r u c t u r e i n p e l a g i c environments (De B e r n a r d i 1981). A s i m i l a r , but l e s s emphatic statement was put f o r t h by L a r k i n (1956), i m p l i c a t i n g c o m p e t i t i o n i n the s t r u c t u r i n g of a number of freshwater f i s h communities. However, a c o n c i s e statement r e g a r d i n g c o m p e t i t i o n among f i s h i s o f t e n e l u s i v e . In s t u d y i n g the fe e d i n g r e l a t i o n s h i p s among s e v e r a l s p e c i e s i n the r i v e r E n d r i c k , 2 M a i t l a n d (1969) concluded that a c o n c l u s i v e statement r e g a r d i n g c o m p e t i t i o n between two or more s p e c i e s i n the w i l d i s normally i m p o s s i b l e . Clady and Luker (1982) in c i t i n g Moyle and L i (1978) p o i n t to the i n s t a b i l i t y of the environment as masking and l i m i t i n g the e f f e c t s of i n t e r s p e c i f i c c o m p e t i t i o n f o r food and space. N e v e r t h e l e s s , s t u d i e s of c o m p e t i t i o n among f i s h have p o i n t e d to s e v e r a l mechanisms t h a t may s u s t a i n s p e c i e s s e p a r a t i o n 1) body s i z e , 2) morphology, 3) h a b i t a t p r e f e r e n c e s , 4) d i f f e r e n t h a b i t a t u t i l i z a t i o n p a t t e r n s , 5) f e e d i n g at d i f f e r e n t depths i n the water column and 6) u t i l i z a t i o n of d i f f e r e n t food types (Keast 1977). T h i s study addresses h a b i t a t , and d i f f e r e n c e s i n h a b i t a t u t i l i z a t i o n p a t t e r n s . More s p e c i f i c a l l y , i t asks i f d i f f e r e n c e s i n h a b i t a t p r e f e r e n c e s and h a b i t a t u t i l i z a t i o n p a t t e r n s occur i n a number of sockeye (Oncorhynchus nerka) producing l a k e s t h a t a l s o house p o t e n t i a l food c o m p e t i t o r s . P o t e n t i a l c ompetitors f o r food with j u v e n i l e sockeye i n c l u d e l a k e w h i t e f i s h (Coreqonus c l u p e a f o r m i s ) , t h r e e s p i n e s t i c k l e b a c k (Gasterosteus a c u l e a t u s ) , kokanee (Oncorhynchus nerka), r e s i d u a l sockeye (Oncorhynchus nerka), pond smelt (Hypomesus o l i d u s ) , and n i n e s p i n e s t i c k l e b a c k ( P u n g i t i u s p u n g i t i u s ) ( F o e r s t e r 1968). Threespine s t i c k l e b a c k have r e c e i v e d the s t r o n g e s t indictment and were c e n t r a l to t h i s study as a p o t e n t i a l c o m p e t i t o r . In a few u n s p e c i f i e d lakes i n B r i t i s h Columbia, F o e r s t e r (1968) remarked that t h r e e s p i n e s t i c k l e b a c k were not a s e r i o u s food competitor but acknowledged that at h i g h d e n s i t i e s they might l i m i t the food a v a i l a b l e to 3 j u v e n i l e sockeye. Intense g r a z i n g of zooplankton by a l a r g e p o p u l a t i o n of t h r e e s p i n e s t i c k l e b a c k i n Long Lake i n 1978 was a t t r i b u t e d with the subsequent small s i z e of sockeye smolts i n 1979 (Stockner et a l . 1980). In Owikeno, Iliamna, and Wood Ri v e r Lakes, t h r e e s p i n e s t i c k l e b a c k have outnumbered p e l a g i c catches of j u v e n i l e sockeye i n c e r t a i n years (Burgner 1959, Ruggles 1965, and Hartman and Burgner 1972). E x c e e d i n g l y low numbers of seaward-migrating young sockeye from Lake Dalnee i n 1945, 1947, and 1948 were a t t r i b u t e d to l a r g e numbers of t h r e e s p i n e s t i c k l e b a c k (Krogius and • Krokhin 1956). Krokhin (1969) concluded t h a t t h r e e s p i n e s t i c k l e b a c k appeared to be the p r i n c i p a l competitor f o r food of young sockeye under the c o n d i t i o n s p r e v a i l i n g i n Kamchatka. In the e a r l y stages of the B r i t i s h Columbia lake f e r t i l i z a t i o n program there were i n d i c a t i o n s from some f e r t i l i z e d l a k e s that t h r e e s p i n e s t i c k l e b a c k b e n e f i t e d more from enhanced zooplankton p r o d u c t i o n than d i d j u v e n i l e sockeye (Stockner and Hyatt 1984). I n v e s t i g a t i o n of c o m p e t i t i o n among or between f i s h has c l a s s i c a l l y employed a n a l y s i s of stomach c o n t e n t s . In the case of j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k the s t u d i e s of Rogers (1968) and Manzer (1976) can be c i t e d . Although l e s s known, K a n e v s k i i and Fleishman (1972) were ab l e to d i s c e r n the food r e l a t i o n s h i p s among f i s h fauna of Lake Dalnee by measurement of Rb and Cs i n v a r i o u s h y d r o b i o n t s . Threespine s t i c k l e b a c k had a Rb/Cs r a t i o of =* 40 which was s i m i l a r to the r a t i o i n b e n t h i c organisms. In c o n t r a s t , j u v e n i l e sockeye had a 4 much l a r g e r Rb/Cs r a t i o of » 160 which was s i m i l a r to the r a t i o in zooplankton. An examination of stomach contents confirmed the food a s s o c i a t i o n s based on Rb/Cs r a t i o s . The method appears w e l l s u i t e d to l a r g e sockeye producing l a k e s where a comprehensive sampling program by a n a l y s i s of stomach contents would be expensive and time consuming. The m e r i t s of i n v e s t i g a t i n g f i s h communities by measuring Cs c o n c e n t r a t i o n s has been c i t e d by s e v e r a l a uthors. Pendleton (1962) mentions the p o t e n t i a l f o r determining the degree of p r e d a t i o n and probable food of i n d i v i d u a l s p e c i e s . Trace element content can a l s o be used to d i s t i n g u i s h between otherwise i d e n t i c a l f i s h and to formulate a l t e r n a t e hypotheses to e x p l a i n t h e i r recent f e e d i n g h i s t o r i e s (Romberg and Renfro 1973). Jenkins (1969) notes t h a t , "... d i f f e r e n c e s i n the c o n c e n t r a t i o n s of r a d i o n u c l i d e s observed f o r a given salmon s p e c i e s from the same l o c a t i o n and run suggest a d i f f e r e n t m i g r a t i o n and/or f e e d i n g p a t t e r n . " Why not s t a b l e elements? The p o s s e s s i o n of an ion r e g u l a t i o n system by f i s h makes them of key i n t e r e s t r e g a r d i n g uptake of r a d i o n u c l i d e s (Fleishman 1973). Comparison of v a r i o u s elements may a l s o be u s e f u l i n i d e n t i f y i n g t rends i n the dynamics of n u t r i e n t c y c l e s i n lakes (Cushing 1979). Trace elements and d i e t i n f i s h have gained more importance due to the presence of hazardous elements among the t r a c e elements and the presence of r a d i o a c t i v e e q u i v a l e n t s i n the environment. Indeed, Cs-137 an a r t i f i c i a l i s o tope of Cs i s a dangerous e m i t t e r due to i t s long h a l f - l i f e and p o t e n t i a l f o r accumulation i n a q u a t i c communities ( G a l l e g o s 1970). S i m i l a r 5 responses i n accumulation p a t t e r n s f o r s t a b l e Cs and Cs-137 suggest that they are b i o l o g i c a l l y e q u i v a l e n t ( S p i g a r e l l i 1971, Kolehmainen 1972, Vanderploeg et a l . 1975). Although Cs i s p a r t i c u l a r l y w e l l bound by i l l i t e f r a c t i o n s (Coughtrey and Thorne 1983), f i s h and presumably i n v e r t e b r a t e s can absorb Cs sorbed to i n g e s t e d c l a y p a r t i c l e s (Vanderploeg et a l . 1975). Freshwater f i s h a c q u i r e e s s e n t i a l l y a l l of t h e i r Cs from i n g e s t e d food and not from water (King 1964, Kevern 1966, G a l l e g o s 1970, Fleishman 1973, and Mauro 1973). Rubidium e n t e r s f i s h i n an i d e n t i c a l manner to Cs. (Fleishman 1973). In comparing f i s h with a plankton d i e t to f i s h with a benthos d i e t , higher c o n c e n t r a t i o n s of Cs-137 were r e p o r t e d i n the l a t t e r (Kolehmainen et a l . 1966 ). The o p p o s i t e has been r e p o r t e d by Hannerz (1968) and Fleishman (1973). The r e s o l u t i o n to t h i s c o n f l i c t may r e s i d e i n the type of lake and the extent to which Cs i s bound by sediments and the f r a c t i o n a v a i l a b l e to p l a n k t o n i n the water column. Comparison of i n s e c t e a t e r s and benthic e a t e r s has a l s o been i n v e s t i g a t e d . In a small l a k e i n the Ume r i v e r system i n Sweden two types of char e x i s t , one whose food c o n s i s t e d mainly of i n s e c t s and was caught i n p e l a g i c nets, the other whose food c o n s i s t e d mainly of bottom organisms and was caught i n nets c l o s e to shore (Hannerz 1968) . Though m o r p h o l o g i c a l l y s i m i l a r , char f e e d i n g on s u r f a c e i n s e c t s had lower Cs-137 c o n c e n t r a t i o n s than char feeding on bottom organisms. In lake Uddjam Sweden, Coregonus l a v a r e t u s ) , a p l a n k t o n e a t e r , had h i g h e r c o n c e n t r a t i o n s of Cs-137 than a composite sample of (Coregonus 6 peled) which f ed on i n s e c t s , and (Coregonus p i d s c h i a n ) which fed on benthic l a r v a e and mollusks (Hannerz 1968). The i n i t i a l use of Rb and Cs by Kan e v s k i i and Fleishman (1972) to determine food r e l a t i o n s h i p s among f i s h i n Lake Dalnee, a sockeye producing l a k e , appears e x t e n d i b l e to other sockeye l a k e s . T h i s i s of p a r t i c u l a r importance as j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k vary i n t h e i r use of h a b i t a t s w i t h i n and among lakes (Manzer 1976, Rogers 1968 and T i l l e r 1974). Since sockeye producing l a k e s examined i n t h i s study share the common f e a t u r e s of being o l i g o t r o p h i c and r e l a t i v e l y deep, the f a c t o r s governing the c i r c u l a t i o n of Rb and Cs should approach a common set of c o n s t r a i n t s as opposed to c o n t r a s t i n g o l i g o t r o p h i c and e u t r o p h i c l a k e s . N e v e r t h e l e s s , there appears to be a c l e a r need f o r more e l a b o r a t e i n v e s t i g a t i o n of Rb and Cs in l a k e s to determine the f a c t o r s r e g u l a t i n g t h i e r d i s t r i b u t i o n in prey and subsequently i n c a r n i v o r e s . No major study of f e e d i n g behavior of f i s h by measurement of Rb and Cs appears to e x i s t i n the l i t e r a t u r e , though such a method appears h i g h l y d e s i r a b l e . The o b j e c t i v e s of t h i s study were t h e r e f o r e s e v e r a l f o l d : 1) to i n v e s t i g a t e o v e r l a p i n d i e t and h a b i t a t use i n f i s h by measuring c o n c e n t r a t i o n s of Rb and Cs i n f i s h and i n t h e i r food. Emphasis was p l a c e d on u t i l i z a t i o n of l i t t o r a l and l i m n e t i c h a b i t a t s by j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k i n Kennedy, C u l t u s , Great C e n t r a l , and lake Aleknagik, l a k e s i n which c o m p e t i t i o n f o r food between these s p e c i e s has been c i t e d . 7 2) to determine i f j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k respond i n a s i m i l a r manner to the presence of Rb and Cs i n t h e i r d i e t . T h i s was e s s e n t i a l i f t i s s u e c o n c e n t r a t i o n s were to be a t t r i b u t e d to d i f f e r e n c e s i n d i e t between f i s h and not p h y s i o l o g y . 3) to determine i f f i s h h e l d onshore i n a l i t t o r a l h a b i t a t would demonstrate d i f f e r e n t Rb and Cs c o n c e n t r a t i o n s than f i s h h e l d o f f s h o r e . Body burdens of Rb and Cs i n f i s h must be i d e n t i f i e d with use of p a r t i c u l a r h a b i t a t s to f u l f i l l o b j e c t i v e " 1 " . 4) to determine i f i n t e r a n n u a l changes i n Rb and Cs c o n c e n t r a t i o n s occur i n zooplankton. Do consumers r e f l e c t the same trends? Without such i n f o r m a t i o n body burdens of Rb and Cs i n f i s h might be i n t e r p r e t e d as a change i n d i e t i n s t e a d of changes i n Rb and Cs c o n c e n t r a t i o n s i n i n g e s t e d prey. 5) to determine y i e l d , type, and q u a l i t y of i n f o r m a t i o n d e r i v e d from measurement of Rb and Cs c o n c e n t r a t i o n s i n f i s h as a means of a s s e s s i n g f e e d i n g behavior among: - benthic and l i m n e t i c forms of t h r e e s p i n e s t i c k l e b a c k r e d s i d e s h i n e r s ( R i c h a r d s o n i u s b a l t e a t u s ) , peamouth chub (M y l o c h e i l u s c a u r i n u s ) , p r i c k l y s c u l p i n (Cottus a s p e r ) , and squawfish ( P t y c h o c h e i l u s o r e g o n e n s i s ) . The a b i l i t y of Rb and Cs to d e t e c t changes i n h a b i t a t and h a b i t a t u t i l i z a t i o n p a t t e r n s must be assessed i n s e v e r a l l a k e s and i n d i f f e r e n t f i s h communities i f a measure of i t s u t i l i t y i s to be a t t a i n e d . 8 Study area Six l a k e s were encompassed by t h i s study, Kennedy, Great C e n t r a l , Babine, C u l t u s , Enos, and Aleknagik. A l l l a k e s have been c l a s s i f i e d as o l i g o t r o p h i c with the e x c e p t i o n of Enos Lake, whose limnology has not been i n v e s t i g a t e d . However, due to abundant v e g e t a t i o n and shallow depth, a c l a s s i f i c a t i o n of mesotrophic to e u t r o p h i c can be adopted (Northcote and L a r k i n 1956). A l l l a k e s are l o c a t e d i n B r i t i s h Columbia with the e x c e p t i o n of Lake A l e k n a g i k , A l a s k a . Basic morphometric data are g i v e n i n Table 1. A r e c o r d of f i s h c a ptured from these lakes i s given i n Table 2. Kennedy Lake i s a c o a s t a l lake l o c a t e d on Vancouver I s l a n d near the town of U c l u e l e t . The B r i t i s h Columbia lake enrichment program has i n c l u d e d i t i n i t s s e r i e s of f e r t i l i z e d l a k e s s i n c e 1978 (Stephens and Stockner, 1983). The lake i s d i v i d e d i n t o two arms, Main and Clayoquot. The Clayoquot arm p e r t a i n s to t h i s study; i t i s marked by the absence of an e x t e n s i v e l i t t o r a l zone, seasonal f l u c t u a t i o n s i n water l e v e l and s t r o n g winds. F e r t i l i z a t i o n of t h i s arm was c a r r i e d out i n a l l years of t h i s study except 1985. Great C e n t r a l Lake i s l o c a t e d on Vancouver I s l a n d a djacent to the c i t y of Port A l b e r n i . The lake has a l s o been i n c l u d e d i n the B r i t i s h Columbia l a k e f e r t i l i z a t i o n program (Stockner and Hyatt 1984), and was undergoing f e r t i l i z a t i o n when sampled as p a r t of t h i s study i n 1983. The lake has been d e s c r i b e d by Manzer (1976). 9 Table 1. Morphometric data f o r i n v e s t i g a t e d l a k e s lake area mean depth water km2 m r e s i d e n c y time yr 1 Kennedy (Clayoquot arm) 1 G r e a t C e n t r a l 2Babine 3 C u l t u s 4Enos 5 A l e k n a g i k 17 51 1.7 51 212 9.7 475 57 18.2 6.3 32 0.71 11 83 30 1 R u t h e r f o r d et a l . , 1986 2 Stockner and Shortreed, 1975 3 R i c k e r , 1937 4 Bentzen et a l . , 1984 5 Hartman and Burgner, 1972 10 Table 2 . Record of f i s h c a ptured i n study l a k e s S c i e n t i f i c name Cult u s 3 Enos^ Aleknagik Kennedy! Great Babine , C e n t r a l 2 Lampetra a y r e s i x Lampetra Taponica x Entosphenus t r i d e n t a t u s x Prosopium c o u l t e r i ' x Prosopium cylindraceum x Prosopium w i l l i a m s o n i x x x Coregonus clupeaformis x . x Coregonus pids c h i a n x Oncorhynchus nerka x x x x x Oncorhynchus k i s u t c h x x x x Oncorhynchus qorbuscha x Oncorhynchus keta x Oncorhynchus tshawytscha - . ' x Salmo c l a r k i x x x Salmo q a i r d n e r i x S a l v e l i n u s malma x x S a l v e l i n u s namaycush ' x S a l v e l i n u s a l p i n u s x Thymallus a r c t I C U S x Hypomesus o l i d u s x Catostomus catostomus x Catostomus commersoni x Catostomus macrocheilus x Richardsonius b a l t e a t u s x Y M y l o c h e i l u s caurinus x x Rhinichthys c a t a r a c t a e x Couesius plumbeus x Ptychochellus oreqonensis x x Lepomis qibbosus ' x Lota l o t a x x Da11ia p e c t o r a l i s x Esox l u c i u s x Gasterosteus aculeatus x x x x x Punq i t i u s p u n q i t i u s ~~ x. Cottus asper x x Cottus a l e u t i c u s x Sources i F i e l d records 1983 to 1985 2Manzer (1976) 3Hartman and Burgner (1972) ^Bentzen et a l . , 1984 11 Babine Lake i s a m u l t i b a s i n lake i n n o r t h e r n B r i t i s h Columbia and i s a t r i b u t a r y to the Skeena R i v e r . A d e s c r i p t i o n of the lake can be found i n Hartman and Burgner (1972). C u l t u s Lake i s i n southwestern B r i t i s h Columbia and i s t r i b u t a r y to the lower F r a s e r R i v e r . A g e n e r a l d e s c r i p t i o n of the lake and i t s h i s t o r y can be found i n Hartman and Burgner ( 1 9 7 2 ) , a more d e t a i l e d d e s c r i p t i o n of i t s p h y s i c a l and chemical c h a r a c t e r i s t i c s i n R i c k e r ( 1 9 3 7 ) . Enos Lake i s a s m a l l lake near Nanoose Bay, Vancouver I s l a n d , which has r e c e i v e d c o n s i d e r a b l e a t t e n t i o n due to the c o e x i s t e n c e of a p a i r of m o r p h o l o g i c a l l y d i s t i n c t s t i c k l e b a c k s (Gasterosteus) (Bentzen et a l . 1984, Bentzen and McPhail 1984, and McPhail 1984). . Lake Aleknagik i s p a r t of the Wood R i v e r Lakes system t r i b u t a r y to B r i s t o l Bay A l a s k a . Hartman and Burgner ( 1 9 7 2 ) p r ovide a g e n e r a l d e s c r i p t i o n of the l a k e . 12 M a t e r i a l s and methods Sample c o l l e c t i o n Six l a k e s were sampled f o r rubidium and cesium content i n one or more of the f o l l o w i n g : water, f i s h , and zooplankton. (Table 3). Water samples were c o l l e c t e d at 15 m, the predominant depth a t which j u v e n i l e sockeye were captured i n Kennedy Lake approximately 1.5hr a f t e r sunset from June to September, 1983-1985. Water samples were c o l l e c t e d u s i n g a p l a s t i c c o l l e c t i n g b o t t l e , s t o r e d i n p l a s t i c bags, packed i n i c e , and l a t e r f r o z e n . F i s h were c o l l e c t e d o f f s h o r e with a 3 x 3 m midwater t r a w l with a mesh s i z e at the cod end of the net of 1/16th of an inch(0.159cm), onshore u s i n g a 15 m beach seine and minnow t r a p s . F i s h were subsequently bagged, i c e d , and l a t e r f r o z e n . Zooplankton was c o l l e c t e d with a S.C.O.R. net (diameter of mesh, 100 um) towed h o r i z o n t a l l y at a depth of 10 to 15m i n areas p r e v i o u s l y trawled f o r f i s h . The c o l l e c t i n g v e s s e l at the end of the net was p l a s t i c . Storage procedure was i d e n t i c a l to water samples. Contamination d u r i n g c o l l e c t i o n Outboard motor e f f l u e n t was a p o t e n t i a l source of contamination d u r i n g c o l l e c t i o n of f i s h as manual e f f o r t was i n s u f f i c i e n t to draw the t r a w l net d i r e c t l y i n t o the boat. To 1 3 Table 3. Samples assessed f o r Rb and Cs content l a k e water zooplankton f i s h Kennedy Clayoquot arm x x Great C e n t r a l x A l e k n a g i k x C u l t u s Enos Babine x X X X X X X 14 determine i f such was the case, water samples were drawn from the c o l l e c t i n g bucket at the cod end of the net. In t o t a l , s i x water samples were e x t r a c t e d , bagged and f r o z e n . A s i m i l a r s e r i e s of samples was taken at the lake s u r f a c e on the downwind si d e of the boat with the motor out of the water. Rubidium c o n c e n t r a t i o n s i n water c o l l e c t e d from the c o l l e c t i n g bucket (CB) at the cod end of the net were not s i g n i f i c a n t l y d i f f e r e n t from water samples taken at the lake surface' (Mann-Whitney t e s t , U=26, p > 0.05, n(1 )=n(2)=6). Cesium c o n c e n t r a t i o n s were s i g n i f i c a n t l y d i f f e r e n t (Mann- Whitney t e s t , U=36, p < .05, n(1)=n(2)=6). The median c o n c e n t r a t i o n of Cs i n CB water was 0.050 ppb, compared to a median of 0.015 ppb f o r lake water. Although s i g n i f i c a n t l y d i f f e r e n t , the high e r c o n c e n t r a t i o n of Cs i n CB water i s n e g l i g i b l e when the smal l f i l m of water c o v e r i n g a f i s h i s c o n s i d e r e d . The source of t h i s i n c r e a s e c o u l d be a t t r i b u t e d to the f i s h , e f f l u e n t from the boat or both i n combination. Instrumentation and a n a l y s i s Rubidium and cesium were measured with a Perkin-Elmer(P-E) 603 f l a m e l e s s atomic a b s o r p t i o n spectrophotometer, equipped with a HGA-2200 g r a p h i t e furnace. E l e c t r o d e l e s s d i s c h a r g e lamps(P-E) were powered by an E.D.L. hi g h v o l t a g e supply and shaded by a red f i l t e r . P y r o l y t i c a l l y coated g r a p h i t e tubes were used f o r a l l d e t e r m i n a t i o n s . A t o m i z a t i o n temperatures were c a l i b r a t e d 15 with a s i l i c o n photodiode temperature sensor. Complete o p e r a t i n g c o n d i t i o n s are l i s t e d i n Appendix I. Peak h e i g h t s were t r a n s c r i b e d by a 056 P-E rec o r d e r with a PRS-10 p r i n t e r sequencer with 10 sec i n t e g r a t i o n . Samples were run at l e a s t 3 times or u n t i l a d e v i a t i o n of 10% or l e s s of the mean was o b t a i n e d . Water volumes were measured to w i t h i n ± 0.5 ml and dry weights to w i t h i n ± 0.5 mg. A l l reagents were checked f o r the presence of Rb and Cs and v e r i f i e d to be contamination f r e e at the d e t e c t i o n l e v e l s l i s t e d i n Appendix I. Any c o n c e n t r a t i o n of reagents from l a r g e r volumes was found to be f r e e from contamination as above. C a l i b r a t i o n curves were c o n s t r u c t e d u s i n g 1000 ppm standards prepared from BDH Suprapur RbCl and Av a l a r reagent C s C l . Standards were d i l u t e d to w i t h i n frame c o n c e n t r a t i o n s i n the samples. The HN0 3 c o n c e n t r a t i o n i n the d i l u t e d standards was matched to the c o n c e n t r a t i o n i n the samples. Water Water samples were thawed to room temperature and f i l t e r e d through a n i t e x mesh(diameter of mesh 100 ixm) i n t o a 1 l i t e r graduated c y l i n d e r . The c y l i n d e r was r i n s e d with 10% HCI between samples, f o l l o w e d by d i s t i l l e d d e i o n i z e d water. The n i t e x mesh was r i n s e d i n d i s t i l l e d d e i o n i z e d water between samples. Water samples were con c e n t r a t e d by e v a p o r a t i o n from volumes 16 of 160 to 600 ml. T r a n s f e r to a 20 ml s c i n t i l l a t i o n v i a l was conducted i n 4 stages with a 1 ml automatic p i p e t , ± 0.005 ml. The s i d e s of the v e s s e l and the bottom were r i n s e d with 1 ml of co n c e n t r a t e d HN0 3 . To t h i s was added 2 ml of d e i o n i z e d d i s t i l l e d water. The s o l u t i o n was allowed to stand f o r 30 sec and then t r a n s f e r r e d to a s c i n t i l l a t i o n v i a l . T h i s was fo l l o w e d by three separate r i n s e s with 3 ml, 2 ml, and 2 ml of d i s t i l l e d d e i o n i z e d water. The s o l u t i o n was evaporated to dryness on a hot p l a t e then r e d i s s o l v e d i n 1 ml of HN0 3, capped and allowed to stand o v e r n i g h t . The open v i a l was then brought q u i c k l y to b o i l i n g , a l lowed to c o o l and subsequently d i l u t e d f o r a n a l y s i s with d i s t i l l e d d e i o n i z e d water to 2 ml f o r Cs and 4 ml f o r rubidium. Zooplankton Zooplankton was thawed and d r i e d to constant weight at 80°C. A n a l y s i s was o r i g i n a l l y performed on a t a r g e t weight of 0.200 g. T h i s weight was l a t e r reduced to 0.100 g and values as low as 0.010 g were analyzed. Repeated a d d i t i o n s of 1 ml q u a n t i t i e s of HN0 3 were r e q u i r e d to d i s s o l v e a number of samples to a c l e a r s o l u t i o n . Samples were heated d u r i n g d i g e s t i o n . 17 F i s h F i s h were e v i s c e r a t e d and d r i e d to c o n s t a n t weight a t 80°C. Whole f i s h were ground i n a s t a i n l e s s s t e e l m i l l . The m i l l was c l e a n e d with a l c o h o l between samples. A n a l y s i s was performed on a t a r g e t weight of 0.200 g but was l a t e r reduced to 0.100 g of p u l v e r i z e d dry t i s s u e s per i n d i v i d u a l f i s h . The complete f i s h was p u l v e r i z e d minus the v i s c e r a . A l l remaining steps were as o u t l i n e d above f o r zooplankton. Food c o n t a i n e d i n the c a r d i a c s e c t i o n of the gut was e x t r a c t e d and grouped a c c o r d i n g to s p e c i e s , and to sex where p o s s i b l e . Contents were d r i e d to c o n s t a n t weight at 80°C. A n a l y s i s was performed on weights ranging from 0.002 to 100 g, which depended on how much m a t e r i a l c o u l d be c o l l e c t e d from stomach c o n t e n t s . A l l remaining steps were as o u t l i n e d above f o r zooplankton with the e x c e p t i o n that i n a number of samples the f i n a l d i l u t i o n was reduced to enable d e t e c t i o n of Rb and Cs at low weights. C o r r e c t i o n f o r i n t e r f e r e n c e e f f e c t s An i n s p e c t i o n of Rb and Cs c o n c e n t r a t i o n s i n both f i s h and zooplankton analyzed p r i o r to 1985, p o i n t e d to a suppression of s i g n a l s t r e n g t h s at high t i s s u e c o n c e n t r a t i o n s (samples d i s s o l v e d i n a c i d ) . T i s s u e c o n c e n t r a t i o n s of Rb and Cs appeared 18 to be underestimated at lower d i l u t i o n s . A separate i n v e s t i g a t i o n of t h i s phenomenon was undertaken, Appendix I I . A s e r i e s of c o r r e c t i o n curves was d e r i v e d and a p p l i e d to a l l f i s h , zooplankton and gut con t e n t s analyzed p r i o r to 1985. The outcome of t h i s study r e s u l t e d i n the estab l i s h m e n t of a d i l u t i o n f a c t o r of 100 or g r e a t e r to e l i m i n a t e i n t e r f e r e n c e i n a l l subsequent a n a l y s i s . C o n c e n t r a t i o n s were s t i l l w i t h i n the d e t e c t i o n l e v e l s l i s t e d i n Appendix I. The exact nature of the problem and subsequent c o r r e c t i o n s are the su b j e t of Appendix I I . Data A n a l y s i s A l l c o n c e n t r a t i o n s were measured i n ppb, 1 ng/g dry weight fo r f i s h , and 1 ng/ml f o r water. Due to l a c k of homogeneity of v a r i a n c e and normal d i s t r i b u t i o n s , most of the data were analyzed u s i n g nonparametric procedures and p r e s e n t e d g r a p h i c a l l y u s i n g q u a r t i l e and median p l o t s as standard 95% co n f i d e n c e l i m i t s were not a p p r o p r i a t e ( f o r use of q u a r t i l e and median p l o t s see Becker and Chambers 1983). In the f o l l o w i n g t e x t "KW", stands f o r one- f a c t o r K r u s k a l W a l l i s t e s t , "NPANOVA", stands f o r two-factor nonparametric a n a l y s i s of v a r i a n c e (Zar, 1984), and "NPMC", stands f o r a nonparametric m u l t i p l e comparisons t e s t , s i m i l a r to a parametric Tukey t e s t (Zar, 1984). 19 CHAPTER 2 Uptake of Cs by coho and t h r e e s p i n e s t i c k l e b a c k I n t r o d u c t i o n The p h y s i o l o g i c a l d i f f e r e n c e i n uptake and e x c r e t i o n r a t e s has been i d e n t i f i e d as one of the most important f a c t o r s r e l a t i n g metals to t h e i r occurrence i n food c h a i n s (Rabe and Stephens 1977). These processes have been l i n k e d to metabolism (Minckley et a l . 1963). However, measurement of metabolic r a t e i s f r e q u e n t l y based on weight or l e n g t h r e l a t i o n s h i p s . E b e r h a r t (1976) s t a t e s that the r e l a t i o n s h i p between the r e l a t i v e s i z e of an i n d i v i d u a l and t i s s u e c o n c e n t r a t i o n s of contaminants i s to be expected. In c i t i n g Olson and F o s t e r (1982), Minckley et a l . (1963) concluded that as a g e n e r a l r u l e younger more r a p i d l y growing f i s h accumulate more r a d i o a c t i v i t y than mature f i s h . T h i s must be i n t e r p r e t e d with c a u t i o n as i t would appear to imply than younger f i s h have longer r e t e n t i o n times. R a p i d l y growing i n d i v i d u a l s i n c o r p o r a t e elements i n t o new t i s s u e s r a ther than e x c r e t e them (Vanderploeg and Kercher 1974). A d d i t i o n a l c o n f u s i o n i n the l i t e r a t u r e r e s i d e s i n the use of the terms o l d and young to d e s c r i b e f i s h . In a study conducted by S p i g a r e l l i (1971) young a c t i v e l y growing largemouth bass (Micropterus salmoides) d e p o s i t e d l e s s Cs-137 i n body 20 t i s s u e s than o l d e r f i s h . However, t o t a l a c t i v i t y of Cs-137 i n ages 2 to 4 was d e s c r i b e d by an i n i t i a l i n c r e a s e to a maximum at about age 3 and a subsequent decrease at age 4. Age 4 f i s h were however, higher i n a c t i v i t y than age 2 f i s h . Hasanen and M i e t t i n e n (1963) found no c l e a r c o r r e l a t i o n between age and Cs-137 content i n f i s h of the same s p e c i e s . Cesium showed no c o r r e l a t i o n with ages 1 to 12 years i n lake t r o u t (Tong et a l . 1974). In c o n t r a s t , the same authors found that Rb c o n c e n t r a t i o n s decreased i n lake t r o u t a f t e r the age of seven. In s t u d i e s d e a l i n g with t r a c e metals, measurement of metabolic r a t e r a t h e r than age would appear to p r o v i d e a b e t t e r b a s i s f o r comparing d i f f e r e n t p o p u l a t i o n s . In b l u e g i l l s (Lepomis m a c r o c h i r u s ) , a b s o r p t i o n of Cs-137 appears to occur mainly i n the gut (Kolehmainen 1972). Croakers (Genyonemus l i n e a t u s ) d i s p l a y an i n i t i a l c o n c e n t r a t i o n of Cs i n the v i s c e r a with gradual movement i n t o muscle t i s s u e s ( B a p t i s t and P r i c e 1962). A comparison of t i s s u e s w i t h i n the common goby (Acanthogobius flavimanus) r e v e a l e d h i g h e s t c o n c e n t r a t i o n s of Cs-137 i n the muscle and lowest i n the g i l l s (Kimura 1984). I t can be concluded that i n long-term s t u d i e s , muscle can be expected to account f o r approximately 70% of the t o t a l body burden i n f i s h (Coughtrey and Thorne 1983). A s s i m i l a t i o n of Cs-137 and Cs-134 i n the banded k i l l i f i s h (Fundulus h e t e r o c l i t u s ) was dependent on both type of food and whether sediment had been i n g e s t e d a l o n g with food (Mauro 1973). A s s i m i l a t i o n of Cs-137 by banded k i l l i f i s h f.rom i n g e s t e d food was c l o s e to 100% f o r Gammarus and b r i n e shrimp Artemius, 59.1 21 to 16.1% f o r algae f o r c e d fed to f i s h by i n j e c t e d i n t o the gut. Uptake of Cs-137 was reduced when animals were f o r c e d f ed, reduced when sediment was added to the d i e t , and p o o r l y absorbed d i r e c t l y from sediment alo n e . Mauro (1973) makes the added n o t a t i o n that i n c o n t r a s t , G a l l e g o s (1970) found h i g h a s s i m i l a t i o n of Cs-137 i n f i s h when the organic content of the sediment was high and the c l a y content was low. A s s i m i l a t i o n of Cs-137 by ca r p from food as r e p o r t e d by Kevern (1966) was 7% f o r d e t r i t u s and 80% f o r a l g a e . A s s i m i l a t i o n i n ca r p was not a f f e c t e d by temperature. The r e t e n t i o n of Cs-137 h a s . a l s o been shown t o vary with temperature and as such c o u l d complicate accumulation p a t t e r n s i n a given l a k e (Gallegos 1970). E x c r e t i o n of Cs-137 occurs i n two phases, a s m a l l e r f r a c t i o n ( r a p i d component, 10-20%), having a h a l f - l i f e of a few days; a second f r a c t i o n (slow component), a h a l f - l i f e of a few to 100 days (Hasanen et a l . 1967). I t i s not known whether b i o l o g i c a l h a l f - l i v e s r e f l e c t any s p e c i f i c metabolic f u n c t i o n (Kolehmainen 1974). G a l l e g o s (1970) has proposed a r e l a t i o n s h i p f o r the h a l f - l i f e of the slow component of Cs-137 e x c r e t i o n i n f i s h based on body weight; where TB1/2 = AW ^, A and b are c o n s t a n t s , TB1/2 i s h a l f - l i f e , and W i s weight. The equation was based on a p h y s i o l o g i c a l r e l a t i o n s h i p but i t was not known i f weight c o u l d be r e l a t e d to TB1/2 independent of age (Gallegos 1970). R e i c h l e et a l . (1970) have c a l c u l a t e d estimates f o r A and b, based on repo r t e d and unpublished r e t e n t i o n times f o r Cs- 137 i n co l d - b l o o d e d v e r t e b r a t e s ( f i s h and amphibians) and i n v e r t e b r a t e s other than i n s e c t s (arthropods and m o l l u s k s ) ; 22 where A = 38.02, b = 0.1390, standard e r r o r of b = 0.03027, temperature = 20 °C. A second set of c o e f f i c i e n t s was proposed fo r i n s e c t s and warm-blooded v e r t e b r a t e s where A =3.458, b = 0.2061, and standard e r r o r of b = 0.01499. The reason why such seemingly d i v e r s e groups possessed s i m i l a r e x c r e t i o n p a t t e r n s was not s t a t e d . The r e l a t i o n s h i p of weight and r a t e of e x c r e t i o n of Cs-137 may a l s o apply to w i t h i n s p e c i e s comparisons. Hasanen et a l . (1967) r e p o r t e d a slow component of e x c r e t i o n f o r Cs-137 of 25 days i n rainbow t r o u t 3.6 to 6.0 months o l d , 55 days f o r 12 to 24 months and 80 days f o r 24 to 36 months. However, data f o r smal l f i s h such as j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k appear to be l a c k i n g , a l t h o u g h the range of wet weight i n the l a t t e r would be i n t e r m e d i a t e between c o l d - b l o o d e d v e r t e b r a t e s and i n v e r t e b r a t e s other than i n s e c t s as presented i n the d e r i v a t i o n by R e i c h l e et a l . (1970) of c o e f f i c i e n t s A and b. Temperature a f f e c t s the e l i m i n a t i o n r a t e of Cs-137 i n f i s h a c c o r d i n g to a Q v 0 of approximately 2 to 3, being slower at c o l d e r temperatures (Mauro 1973). In freshwater perch the slow component of e x c r e t i o n was 175-200 days at 15 °C and double or t r i p l e d at 5 °C (Fleishman 1973). Hasanen et a l . (1967) r e p o r t e d a 200 to 300% i n c r e a s e i n the b i o l o g i c a l h a l f - t i m e f o r the slow component of e x c r e t i o n i n the roach ( L e u c i s c u s r u t i l u s ) with a r e d u c t i o n i n temperature from 15 °C with a range of ±5°C to 5°C. R e t e n t i o n times f o r Cs-137, slow component i n rainbow t r o u t (Salmo g a i r d n e r i ) , were a f f e c t e d not only by a weight temperature i n t e r a c t i o n but a l s o by i n c r e a s e s i n weight 23 (Gallegos 1970 ). In c o n c l u s i o n , a l a r g e number of f a c t o r s appear to i n f l u e n c e the c o n c e n t r a t i o n of Cs and p o s s i b l y Rb i n f i s h t i s s u e s . The main o b j e c t i v e of the f o l l o w i n g study was to determine i f t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye a s s i m i l a t e Rb and Cs i n a s i m i l a r manner. To c o r r e c t l y i n t e r p r e t Rb and Cs c o n c e n t r a t i o n s i n f i s h i t must be demonstrated whether t i s s u e c o n c e n t r a t i o n s r e f l e c t d i f f e r e n c e s i n d i e t or p h y s i o l o g y . A secondary o b j e c t i v e was to determine how r a p i d l y both s p e c i e s would respond to a change i n Rb and Cs c o n c e n t r a t i o n s i n t h e i r d i e t . T h i s was of p a r t i c u l a r importance i n d etermining whether movement of t h r e e s p i n e s t i c k l e b a c k onshore to breed i n the summer would r e s u l t i n a change i n d i e t as indexed by a change i n Rb and Cs c o n c e n t r a t i o n s i n t h e i r t i s s u e s . C o n s t r a i n t s on moving enough equipment to Kennedy Lake, coupled with o v e r a l l c o s t s , d i d not permit an assessment of a s s i m i l a t i o n r a t e s f o r both Rb and Cs. Cesium was chosen due to a l a r g e body of l i t e r a t u r e on t h i s element, i n c l u d i n g t o x i c i t y to zooplankton, that was not a v a i l a b l e f o r rubidium. 24 M a t e r i a l s and methods Uptake experiments were conducted at Kennedy Lake i n l a t e J u l y and e a r l y August, 1985. Limnetic t r a w l i n g f o r t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye was undertaken on J u l y 28th. Although t h r e e s p i n e s t i c k l e b a c k were captured by l i m n e t i c t r a w l i n g , repeated l i m n e t i c t r a w l i n g e f f o r t s f a i l e d to y i e l d any j u v e n i l e sockeye. J u v e n i l e coho (Oncorhynchus k i s u t c h ) were t h e r e f o r e captured from a s m a l l stream i n the n o r t h p o r t i o n of Clayoquot arm. A second group of t h r e e s p i n e s t i c k l e b a c k was captured u s i n g a beach s e i n e ; these were t r e a t e d as a separate group from the two mentioned above. A l l f i s h were h e l d immediately a f t e r c a p t u r e f o r at l e a s t 2 days i n wire e n c l o s u r e s made of hardware c l o t h of l / 8 t h inch(0.32cm) square mesh, p l a c e d in the l i t t o r a l zone where s p r i n g water i n t e r m i x e d with l a k e water, at a temperature of 12-14°C. S t a r t i n g on August 4th, zooplankton were c o l l e c t e d d u r i n g the l a t t e r p a r t of the a f t e r n o o n i n Kennedy Lake i n areas p r e v i o u s l y t r a w l e d f o r j u v e n i l e sockeye. On each day the accumulated c a t c h from 2 twenty minute tows were p l a c e d i n a 77.4 1 p l a s t i c c o n t a i n e r f i l l e d with 70 1 l i t e r s of lake water f i l t e r e d through a 100 ym mesh net. The container, was immersed i n the l i t t o r a l zone of the l a k e . A c o n t a i n e r thus f i l l e d served as one d a i l y f e e d i n g u n i t f o r a l l the f i s h , and was r e s t o c k e d every 24 hours. Exposure time of the zooplankton to C s C l was 24 h r s . Cesium e n r i c h e d zooplankton was o b t a i n e d by adding C s C l at a c o n c e n t r a t i o n of 1000 ppb (0.070g) to the c o n t a i n e r before the a d d i t i o n of zooplankton. Water i n the 25 c o n t a i n e r was f i l t e r e d through 100 MM mesh b e f o r e the a d d i t i o n of C s C l and zooplankton. The c o n t a i n e r was h e l d at a constant volume of 70 1 f o r a l l of the CsCl a d d i t i o n s . The c o n c e n t r a t i o n of Cs was 10 times l e s s than the 5 day LD c o n c e n t r a t i o n f o r Gammarus and C y c l o p s (10000 ppb) as determined by Hakonson et a l . (1971). Uptake experiments f o r f i s h were conducted in. 12, 77.4 1 p l a s t i c c o n t a i n e r s . C o n t a i n e r s were p l a c e d at the base of a nearby w a t e r f a l l t h a t emptied i n t o the l a k e . Twelve garden h o s e s ( l / 2 i n diameter (1.27cm), fed water from the head of the f a l l s i n t o each c o n t a i n e r . Water temperatures remained w i t h i n 14 to 16°C d u r i n g the course of the i n v e s t i g a t i o n . Water flow was i n t e r r u p t e d d u r i n g a 2 hour f e e d i n g p e r i o d between 2000h and 2200h. J u v e n i l e coho were assig n e d to 6 c o n t a i n e r s a t a d e n s i t y of 20 per c o n t a i n e r . Three of these c o n t a i n e r s served as r e p l i c a t e treatments. S i m i l a r l y , t h r e e s p i n e s t i c k l e b a c k were a s s i g n e d to 6 c o n t a i n e r s at a d e n s i t y of 10 onshore s t i c k l e b a c k ( f i r s t d o r s a l spine c l i p p e d ) and 10 o f f s h o r e s t i c k l e b a c k per c o n t a i n e r . F i s h were h e l d f o r 4 days i n c o n t a i n e r s b e f o r e i n t r o d u c t i o n of the e n r i c h e d zooplankton. F i s h were fed the f i r s t 3 days with u n t r e a t e d zooplankton. They were s t a r v e d on the f o l l o w i n g day and subsequently fed cesium e n r i c h e d zooplankton every 24hr fo r 8 days. Cesium e n r i c h e d zooplankton was a l l o t t e d e q u a l l y among a l l c o n t a i n e r s a f t e r undergoing thorough mix i n g . Water volumes were reduced i n the c o n t a i n e r s c o n t a i n i n g f i s h so no water overflow o c c u r r e d due to the a d d i t i o n of zooplankton. 26 Zooplankton were not r i n s e d . F i s h were h a r v e s t e d a f t e r the f e e d i n g p e r i o d before the water flow was reconnected. Four c o n t a i n e r s r e p r e s e n t i n g a l l three groups were ha r v e s t e d on days 2, 4,and 8 f o l l o w i n g the s t a r t of the Cs e n r i c h e d d i e t . A sample of 8 f i s h from a l l three groups was a l s o c o l l e c t e d p r i o r to the s t a r t of the Cs e n r i c h e d d i e t f o r i n i t i a l c a l c u l a t i o n of Cs c o n c e n t r a t i o n s . M o r t a l i t i e s were not the same among a l l c o n t a i n e r s over the course of the experiment, however, a minimal sample s i z e of 8 f i s h was o b t a i n e d from each c o n t a i n e r on the sampling dates l i s t e d above. The stomach contents of a l l 8 f i s h w i t h i n each subsample were p o o l e d to provide s u f f i c i e n t sample weight p r i o r to a n a l y s i s f o r Cs i n stomach c o n t e n t s . In a d d i t i o n , on August 4th, a second c o n t a i n e r of Cs e n r i c h e d zooplankton was obtained i n i d e n t i c a l manner to the ones from which f i s h were f e d . Two samples of Cs s p i k e d zooplankton were taken from t h i s a d d i t i o n a l c o n t a i n e r to measure the c o n c e n t r a t i o n of Cs i n zooplankton a f t e r 24hrs of exposure to 1000 ppb C s C l . 27 R e s u l t s Cesium e n r i c h e d zooplankton was consumed by j u v e n i l e coho and t h r e e s p i n e s t i c k l e b a c k as i n d i c a t e d by an i n c r e a s e i n the body burden of Cs and the presence of food i n the gut ( F i g u r e s 1-2). The r a t e of uptake of Cs was not s i g n i f i c a n t l y d i f f e r e n t among treatment groups (F=0.021; df=5,l86; P > 0.05) nor were there s i g n i f i c a n t d i f f e r e n c e s i n mean v a l u e s (F=0.134; d f = l 0 , l 8 l ; P > 0.05, Kleinbaum and Kupper 1978, p.188). A l l s i x r e g r e s s i o n equations thus reduced to the s i n g l e equation, Csfppb] = 1100 + 850[ e l a p s e d d a y s ] , which . was h i g h l y s i g n i f i c a n t ( F=556; d f = 1 , l 9 l ; P < 0.01). The c o n c e n t r a t i o n s of Cs i n t h r e e s p i n e s t i c k l e b a c k from both onshore and o f f s h o r e areas on day 4 had p a r t i c u l a r l y l a r g e r e s i d u a l s from the average r e g r e s s i o n ( F i g u r e 1). The wet weight of food i n f i s h stomach on day 4 e x p l a i n e d some of the d e v i a t i o n and i t s i n c l u s i o n i n the o v e r a l l r e g r e s s i o n model was s i g n i f i c a n t ( F i g u r e 2; Cs[ppb]=972 + 682[gut wet weight (g)] + 6170[elapsed d a y s ] , stepwise r e g r e s s i o n , F=147; df=2,141; P < 0.01). The a d d i t i o n of dry weight of f i s h as a t h i r d v a r i a b l e i n the r e g r e s s i o n d i d not e x p l a i n any of the remaining v a r i a b i l i t y i n uptake r a t e s of Cs (stepwise r e g r e s s i o n , F=2.96; df=3,141; P > 0.05), presumably r e f l e c t i n g t h a t water content was more or l e s s a constant p r o p o r t i o n of t o t a l weight of f i s h . The c o n c e n t r a t i o n s of Cs i n stomach c o n t e n t s of f i s h having fed on Cs e n r i c h e d zooplankton were i n the range of 7000 to 22000 ppb (Table 4). The c o n c e n t r a t i o n of Cs i n zooplankton a f t e r 24hrs of exposure to 1000 ppb C s C l was 7900 ppb and 28 F i g u r e 1. Uptake of Cs i n t h r e e s p i n e s t i c k l e b a c k captured o f f s h o r e and onshore and coho captured from a t r i b u t a r y stream, p l o t t e d a g a i n s t e l a p s e d days(0,2,4,8), s i n c e s t a r t of Cs e n r i c h e d zooplankton d i e t . Experiment was conducted with a r e p l i c a t e treatment represented by the r i g h t - hand val u e s ( t r i a n g l e s ) on each day of sampling. Values have been been d i s p l a c e d from e l a p s e d days f o r g r e a t e r r e s o l u t i o n . V e r t i c a l bars represent 95% c o n f i d e n c e l i m i t s on the mean. Sample s i z e i s e i g h t . 10000 8000 6000 4000 - 2000 - 0 10000 8000 6000 4000 2000 0 h 10000 8000 6000 4000 2000 0 s t i c k l e b a c k o f f s t i c k l e b a c k on coho stream i • i 0 8 30 F i g u r e 2. Q u a r t i l e and median p l o t s f o r wet weight of gut contents f o r t h r e e s p i n e s t i c k l e b a c k and coho p l o t t e d a g a i n s t the 2nd, 4th, and 8th day s i n c e the s t a r t of the Cs e n r i c h e d zooplankton d i e t . Experiment was conducted with a r e p l i c a t e treatment represented by r i g h t - h a n d val u e s on each day of sampling. Values have been d i s p l a c e d from e l a p s e d days f o r g r e a t e r r e s o l u t i o n . There are no data f o r day "0" as f i s h were s t a r v e d 24hrs before the s t a r t of the experiment. Sample s i z e i s e i g h t . A long h o r i z o n t a l l i n e i s drawn through the median of the d a t a . The upper and lower extremes of the t h i c k v e r t i c a l l i n e represent the upper and lower q u a r t i l e s . - The upper end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the l a r g e s t o b s e r v a t i o n that i s l e s s than or equal to the upper q u a r t i l e p l u s 1.5 x the i n t e r q u a r t i l e range. The lower end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the s m a l l e s t o b s e r v a t i o n that i s g r e a t e r than or equal to the lower q u a r t i l e minus 1.5 x the i n t e r q u a r t i l e range. A l l v a l u e s o u t s i d e the upper and lower extremes of the t h i n v e r t i c a l l i n e are p l o t t e d as "*". 31 cn 4-1 03 O) 4 days a 32 8000 ppb (2 samples taken). By c o n t r a s t unenriched zooplankton from the same lake at the same time of year had Cs c o n c e n t r a t i o n s of approximately 300 ppb (Chapter 3 ) . E l e v a t e d c o n c e n t r a t i o n s of Cs i n f i s h having f ed on Cs e n r i c h e d zooplankton suggested uptake of Cs by f i s h , as gut contents were analyzed s e p a r a t e l y . S e l e c t i o n of c e r t a i n prey items by f i s h was suggested by two ranges of Cs c o n c e n t r a t i o n s found i n stomach contents (Table 4), one from 18000-22000 ppb and the other from 7600-9700 ppb. Cesium e n r i c h e d zooplankton sampled d i r e c t l y from the s t o c k i n g c o n t a i n e r on day one of the Cs e n r i c h e d d i e t was 7900 ppb and 8000 ppb Cs (two samples taken). However, the absence of data f o r a l l groups on a l l days makes f u r t h e r i n t e r p r e t a t i o n i l l - a d v i s e d . 33 T a b l e 4. C o n c e n t r a t i o n s of Cs i n t h e stomach c o n t e n t s of t h r e e s p i n e s t i c k l e b a c k and coho o f f e r e d a Cs e n r i c h e d d i e t . F i s h stomachs were empty a t the s t a r t of the e x p e r i m e n t (day 0 ) , as f i s h were s t a r v e d p r i o r t o the i n t r o d u c t i o n of the Cs e n r i c h e d d i e t . Stomach c o n t e n t s from the 8 f i s h i n each g r o u p were p o o l e d p r i o r t o a n a l y s i s f o r Cs c o n t e n t . f i s h group Cs ppb (days) 4 s t i c k l e b a c k - o f f 19000 20000 s t i c k l e b a c k - o f f r e p l i c a t e s t i c k l e b a c k - o n 1 9700 20000 22000 7600 s t i c k l e b a c k - o n r e p l i c a t e c o h o - s t r e a m 9200 7600 18000 8200 9300 8300 c o h o - s t r e a m r e p l i c a t e 8000 ** ** 1 o f f , means c a u g h t o f f s h o r e , o n , means caught o n s h o r e , s t r e a m means c a u g h t i n a s tream w i t h i n the same l a k e as j u v e n i l e s o c k e y e and t h r e e s p i n e s t i c k l e b a c k . * f i n a l d r y w e i g h t too s m a l l f o r a c c u r a t e r e a d i n g * * i c e c r y s t a l damage made s e p a r a t i o n of gut c o n t e n t s from stomach w a l l t i s s u e s q u e s t i o n a b l e 34 D i s c u s s i o n Zooplankton h e l d i n Cs e n r i c h e d water i n c r e a s e d Cs body burdens w i t h i n 24 hours. A s i m i l a r experiment was performed by King (1964) with pure c u l t u r e s of Daphnia pulex. When exposed to water c o n t a i n i n g 1000 ppb Cs, t i s s u e c o n c e n t r a t i o n i n Daphnia pulex rose from approximately 1.2 ppb to 10000 ppb. In the present study, an i n c r e a s e i n Cs c o n c e n t r a t i o n s i n zooplankton from approximately 300 ppb to 8000 ppb was apparent. The path of uptake i n the l a t t e r was not known but Cs c o n c e n t r a t i o n s i n Daphnia pulex were enhanced by d i r e c t i n g e s t i o n of Cs c o n t a i n e d i n Chlamydomonas (King 1 964). The use of a 100 jum diameter mesh as a f i l t e r i n the c u r r e n t study does not preclu d e the absence of phytoplankon and b a c t e r i a i n the water to which CsCl and ne t t e d zooplankton were added. Enough time f o r uptake of Cs by zooplankton from food r a t h e r than water seems l i k e l y though gut cont e n t s i n zooplankton may c o n s t i t u t e the major source. Uptake of Cs-137 by freshwater algae appears r a p i d . Davis (1963) r e p o r t s C h l o r e l l a as a c h i e v i n g a steady s t a t e of Cs-137 w i t h i n 15 hours. In a study by Hakonson et a l . (1971), s t a b l e Cs i n zooplankton was d e t e c t e d w i t h i n 1.5 to 4 hours a f t e r a small lake was e n r i c h e d with Cs. The mode of uptake was not i n v e s t i g a t e d . ' Cesium c o n c e n t r a t i o n s i n stomach samples from t h r e e s p i n e s t i c k l e b a c k and coho were i n c e r t a i n cases c o n t r a s t e d with c o n c e n t r a t i o n s measured i n zooplankton used as prey. S e l e c t i o n of c e r t a i n prey items by f i s h from the zooplankton mix was suggested. In support of t h i s h y p o t h e s i s , high and low 35 c o n c e n t r a t i o n s of Cs i n stomach contents were d e t e c t e d on the same day, though a l l i n i t i a l prey were i s s u e d from the same zooplankton s t o c k . Threespine s t i c k l e b a c k and j u v e n i l e sockeye salmon are known to be s e l e c t i v e p r e d a t o r s on zooplankton (Eggers 1982). Both salmonids and t h r e e s p i n e s t i c k l e b a c k have been noted to express l e a r n i n g i n the s e l e c t i o n of prey ( N i l s s o n 1958, M i l i n s k i and H e l l e r 1978). Repeated s e l e c t i o n of c e r t a i n prey items has been r e p o r t e d i n brook t r o u t ( S a l v e l i n u s f o n t i n a l i s ) , c u t t h r o a t t r o u t (Salmo c l a r k i ) , and rainbow t r o u t (Salmo q a i r d n e r i ) (Byran and L a r k i n 1 972). Although examination of gut con t e n t s would r e s o l v e the q u e s t i o n of prey s e l e c t i o n , alone i t would f a i l to e x p l a i n the v a r i a b i l i t y i n Cs c o n c e n t r a t i o n s . Subsequent a n a l y s i s f o r Cs content would be r e q u i r e d . A f t e r s o r t i n g of stomach contents i n t o s eparate taxa, sample weight would probably be below the d e t e c t i o n l e v e l f o r cesium. A p p r o p r i a t e taxa c o u l d be s o r t e d from the o r i g i n a l Cs e n r i c h e d zooplankton and then analyzed. However, many i n d i v i d u a l s would be r e q u i r e d to reach a minimum dry weight f o r a n a l y s i s . Such a p r o j e c t was beyond the res o u r c e s of the present p r o j e c t . V a r i a b i l i t y i n Cs c o n c e n t r a t i o n s i n stomach contents may a l s o have another e x p l a n a t i o n . F i s h may d i g e s t d i f f e r e n t s p e c i e s of zooplankton at d i f f e r e n t r a t e s . The l a t t e r would imply t h a t coho and t h r e e s p i n e s t i c k l e b a c k had a c t u a l l y r e c e i v e d the same t o t a l dose of Cs, whereas t h e i r r a t e s of a s s i m i l a t i o n were d i f f e r e n t i n accordance with s p e c i e s of prey consumed. T h i s may e x p l a i n the s i m i l a r r a t e s of uptake of Cs by both 36 s p e c i e s d e s p i t e v a r i a t i o n i n Cs c o n c e n t r a t i o n s i n stomach c o n t e n t s . Some s p e c i e s of zooplankton possess high f a t content (Kolehmainen et a l . 1968a), which i s known to a l t e r r a t e s of d i g e s t i o n i n c e r t a i n f i s h ( W i n d e l l 1978). T h i s hypothesis c o u l d be addressed by s e l e c t i v e l y f e e d i n g f i s h Cs e n r i c h e d zooplankton of the same s p e c i e s f o r each taxa to be i n v e s t i g a t e d . Such an undertaking was beyond the r e s o u r c e s of the present p r o j e c t . Rate of uptake of Cs by j u v e n i l e coho and a d u l t t h r e e s p i n e s t i c k l e b a c k was not s i g n i f i c a n t l y d i f f e r e n t i n the present study. The e x t e n s i o n of t h i s o b s e r v a t i o n to j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k i s probably v a l i d . J u v e n i l e coho used i n t h i s study were of comparable s i z e to j u v e n i l e sockeye caught at the same time of year, one year e a r l i e r . Puckett and D i l l (1984) observed no s i g n i f i c a n t d i f f e r e n c e i n metabolic r a t e between j u v e n i l e sockeye and j u v e n i l e coho of 4.0 to 6.0cm l e n g t h . In a r e s p i r a t i o n study by Krokhin (1959) there was evidence to suggest that any d i f f e r e n c e i n s i z e between j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k would not a f f e c t metabolic r a t e . Evidence would appear to suggest that j u v e n i l e coho can be used as a model f o r uptake of Cs i n j u v e n i l e sockeye. There appears to be no p u b l i s h e d i n f o r m a t i o n on uptake or e x c r e t i o n of Rb i n freshwater f i s h i n terms of c o n c e n t r a t i o n s . There i s evidence to suggest that Rb behaves i n b i o l o g i c a l systems i n a s i m i l a r manner to potassium (Tanka et a l . 1977). Comparable behavior has been noted f o r Cs (Davis 1963, W i l l i a m s and P i c k e r i n g 1961). Rubidium and Cs a l s o bear chemical s i m i l a r i t i e s (Poluektov and Mishchenko 1962). C o n c e n t r a t i o n s of 37 Rb a r e however, h i g h e r i n the g e n e r a l e n v i r o n m e n t ; b e i n g on t h e a v e r a g e 0.009% of the e a r t h ' s c r u s t f o r Rb and o n l y 0.0003% f o r Cs ( L e v i n s o n 1974). T h e r e b e i n g no e v i d e n c e t o the c o n t r a r y i t was t e n t a t i v e l y assumed t h a t Rb behaves i n a s i m i l a r manner t o Cs i n f r e s h w a t e r f i s h . In c o n c l u s i o n , a g e n e r a l s i m i l a r i t y im m e t a b o l i c r a t e f o r j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k ( K r o k h i n 1959) c o u p l e d t o p r e s e n t r e s u l t s i n d i c a t i n g no s i g n i f i c a n t d i f f e r e n c e i n uptake r a t e s of Cs by j u v e n i l e coho and t h r e e s p i n e s t i c k l e b a c k , s u g g e s t e d s i m i l a r e x c r e t i o n r a t e s i n a l l t h r e e s p e c i e s a t the same t e m p e r a t u r e . A l t h o u g h not c o n c l u s i v e , t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye appear t o have s i m i l a r r e s p o n s e s t o changes i n Rb and Cs c o n c e n t r a t i o n s i n t h e i r p r e y . 38 CHAPTER 3 T r a n s f e r experiments, r o l e of sediments I n t r o d u c t ion Sediments have been shown to act as s i n k s f o r many contaminants, t r a c e metals, and r a d i o n u c l i d e s (Cushing 1979). Cesium appears to be removed from l a k e s mainly by f l u s h i n g and movement of Cs tb lower l a y e r s of the sediment (G a l l e g o s 1970). McDonald et a l . (1971) i n an examination of water, b i o t a , and sediment, d e t e c t e d g r e a t e s t c o n c e n t r a t i o n s of Cs-137 i n the l a t t e r . Both o r g a n i c and i n o r g a n i c f r a c t i o n s of sediment appear capable of a b s o r p t i o n of Cs-137 (Pendleton and Hanson 1958 and Gustafson 1969). The c o n c e n t r a t i o n of Cs and i t s a s s o c i a t i o n with sediment appears to depend on lake type. Low c o n c e n t r a t i o n s of Cs i n f i s h have been a s s o c i a t e d with t u r b i d l a k e s , probably due to s o r p t i o n to suspended c l a y p a r t i c l e s and c l a y c o n t a i n i n g bottom sediments (Kolehmainen and Nelson 1969). Such was the case i n a Cs-137 p o l l u t i o n experiment c a r r i e d out i n a e u t r o p h i c lake by Kolehmainen et a l . (1968b). S p i k i n g of an o l i g o t r o p h i c lake by the these authors r e s u l t e d i n a much slower removal time f o r Cs- 137 compared to the e u t r o p h i c l a k e . The major s i t e of removal i n the l a t t e r was along the s h o r e l i n e . Vanderploeg et a l . (1976) noted that bottom sediments were not a major source of 39 Cs-137 to b i o t a when Cs-137 was added to a small e u t r o p h i c l a k e . C o n c e n t r a t i o n s c o u l d not be measured i n sediments i n a s i m i l a r experiment conducted by the same authors i n an o l i g o t r o p h i c l a k e . Accumulation of Cs-137 i n sediments may not occur i n c e r t a i n l a k e s . Preston et a l . (1967) found no accumulation of Cs-137 from f a l l o u t sources i n sediments over a p e r i o d of 6 years i n lake Trawsfynydddin i n the B r i t i s h I s l e s . Some i n v e r t e b r a t e s appear capable of r e c y c l i n g Cs-137 from sediments (Mauro 1973). In c e r t a i n cases amphipods may r e c y c l e Cs-137 from d e t r i t u s and sediment to the food c h a i n (AEC r e p o r t 1967). D e t r i t u s i s l i k e l y to c o n t a i n high l e v e l s of t r a c e metals (Rabe and Stephens 1977). Mauro (1973) has i n d i c a t e d a c l e a r need to e s t a b l i s h the r o l e of sediment i n uptake of Cs-137 by f i s h . In the sockeye producing l a k e s i n v e s t i g a t e d i n t h i s study the o p p o r t u n i t y f o r con t a c t with sediments a r i s e s i n the l i t t o r a l zone f o r both j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k . Since there were st r o n g i n d i c a t i o n s from the l i t e r a t u r e that j u v e n i l e sockeye and thr e e s p i n e s t i c k l e b a c k d i f f e r i n the use of these h a b i t a t s (Burgner 1959, Rogers 1968, and Manzer 1976), there was a need to e s t a b l i s h whether t i s s u e c o n c e n t r a t i o n s of Rb and Cs i n f i s h would r e f l e c t a forage use of these areas. Secondly, i t was uncle a r as to whether type of sediment i n areas o c c u p i e d by j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k would a f f e c t Rb and Cs c o n c e n t r a t i o n s i n f i s h . Two hy p o t h e s i s were proposed: 1) the c o n c e n t r a t i o n s of Rb and Cs i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k h e l d onshore would d i f f e r from j u v e n i l e sockeye and 40 t h r e e s p i n e s t i c k l e b a c k h e l d o f f s h o r e , and 2) type of sediment over which f i s h were h e l d would be r e f l e c t e d i n t h e i r t i s s u e c o n c e n t r a t i o n s of Rb and Cs. 41 M a t e r i a l s and methods Short-term experiment: t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye J u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k were captured o f f s h o r e i n Kennedy Lake on May 24, 1984. F i s h were h e l d i n Kennedy lake i n open face wire cage of hardware c l o t h ( l / 8 t h inch(0.32cm) square mesh), immersed i n a d e p r e s s i o n dug approximately 10 m from shore to reach an underground s p r i n g at a temperature of 4 to 5°C. F i s h were h e l d u n t i l May 29 when they were t r a n s f e r r e d to wire cages ( r a d i u s 0.45 m, h e i g h t 0.91 m), at s p e c i f i c s i t e s w i t h i n the l a k e . One cage was a l l o t t e d f o r each s p e c i e s per s i t e and twenty f i s h were housed i n each. The onshore s i t e was l o c a t e d i n a shallow cove(< 3 m deep) frequented by t h r e e s p i n e s t i c k l e b a c k . S u b s t r a t e type i n the cove was a mixture of sand and mud with s c a t t e r e d v e g e t a t i o n . O f fshore s i t e s were d e s i g n a t e d by cages suspended from guide ropes spanning a sma l l i s l a n d and the mainland over a d i s t a n c e of approximately 160 m ( F i g u r e 3 ). O f f s h o r e cages were g r a d u a l l y lowered to a depth of 15m, the predominant depth at which j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k were ca p t u r e d i n Kennedy Lake a t approximately 1.5hrs a f t e r sunset from June to September 1983-1985. The o f f s h o r e s i t e can be d e s c r i b e d as a r e c t a n g u l a r t r e n c h 32 m i n depth. The surrounding s h o r e l i n e 42 F i g u r e 3. Map of Kennedy Lake showing s i t e s of h o l d i n g experiments both short-term and long-term(next s e c t i o n ) . KENNEDY LAKE C L A Y O Q U O T ARM 43 44 c o n s i s t e d of sheer rock, the nearest beach was a c r o s s the l a k e . F i s h were h a r v e s t e d on J u l y 4th, 1984 and analyzed f o r Rb and Cs content. Stomach c o n t e n t s were analyzed when enough m a t e r i a l c o u l d be o b t a i n e d . To determine i f r e s t r i c t i n g f i s h to wire cages would a l t e r the c o n c e n t r a t i o n of Rb and Cs i n stomach contents compared to f i s h with f u l l a c c e s s to the to the s u b s t r a t e , 40 t h r e e s p i n e s t i c k l e b a c k c a p t u r e d o f f s h o r e were h e l d onshore i n a wire cage (same s i z e and form as above) on a s u b s t r a t e of sand and mud, and 40 f i s h were h e l d i n a c i r c u l a r wire e n c l o s u r e (diameter 1.5m, same wire as cages) which allowed f u l l access to the same type of s u b s t r a t e . C o n c e n t r a t i o n s of Rb and Cs were measured i n the stomach c o n t e n t s of both groups. Long-term experiment: t h r e e s p i n e s t i c k l e b a c k Threespine s t i c k l e b a c k were captured o f f s h o r e i n Kennedy Lake on August 6th, 1984. F i s h were h e l d i n s p r i n g water (11 to 13°C) u n t i l August 13th when they were t r a n s f e r r e d to wire cages (hardware c l o t h , l / 8 t h i n mesh(0.32cm) at a d e n s i t y of 20 per cage ( r a d i u s 0.45 m, h e i g h t 0.91 m). Cages were p l a c e d i n water l e s s than 4 m deep. One cage was p l a c e d on each of the s u b s t r a t e s : sand, sand-mud with v e g e t a t i o n , gravel-mud, and cobble ( > 5 cm d i a m e t e r ) . F i s h were l e f t over winter and harvested on A p r i l 28th, 1985. Threespine s t i c k l e b a c k were captured o f f s h o r e on A p r i l 26th, 1985 to provide a comparison data s e t . Cesium and Rb c o n c e n t r a t i o n s were measured for a l l 45 f i s h . Stomach contents were analyzed i f enough m a t e r i a l c o u l d be amassed. 46 R e s u l t s Short-term experiments: t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye F i s h m o r t a l i t i e s were d i f f e r e n t among s i t e s . Out of an i n i t i a l s t o c k i n g d e n s i t y of 20 f i s h per cage the number of s u r v i v i n g i n d i v i d u a l s were: 16 j u v e n i l e sockeye ( h e l d onshore), 14 t h r e e s p i n e s t i c k l e b a c k ( h e l d onshore), 5 j u v e n i l e sockeye (h e l d o f f s h o r e ) , and 7 t h r e e s p i n e s t i c k l e b a c k ( h e l d o f f s h o r e ) . The sample s i z e s i n the f o l l o w i n g a n a l y s e s were 8 f i s h or l e s s depending on s u r v i v a l as i n d i c a t e d above. In combination, both h o l d i n g s i t e s and s p e c i e s s i g n i f i c a n t l y a f f e c t e d the c o n c e n t r a t i o n s of Rb and Cs i n f i s h ( F i g u r e s 4-5; Rb: H=20.52, Cs: H=14.85, P <0.05; df=3). The only s i g n i f i c a n t d i f f e r e n c e f o r w i t h i n s p e c i e s but between s i t e comparisons of Rb and Cs was higher c o n c e n t r a t i o n s of Cs i n j u v e n i l e sockeye h e l d onshore (Table 5 ). A l l other s i g n i f i c a n t comparisons i n v o l v e d d i f f e r e n c e s between s p e c i e s w i t h i n s i t e s or d i f f e r e n t s p e c i e s between s i t e s (Table 5). I t was apparent that s i g n i f i c a n t d i f f e r e n c e s i n v o l v i n g Rb were not p a r a l l e l e d by s i m i l a r f i n d i n g s f o r Cs (Table 5). When s i g n i f i c a n t d i f f e r e n c e s i n Rb and Cs c o n c e n t r a t i o n s i n f i s h were d e t e c t e d between s i t e s , higher c o n c e n t r a t i o n s were a s s o c i a t e d with onshore l o c a t i o n s (Table 5). C o n c e n t r a t i o n s of Rb and Cs i n stomach contents of f i s h h e l d onshore and o f f s h o r e demonstrated no i d e n t i f i a b l e p a t t e r n i n c o n j u n c t i o n with body burden of Rb and Cs i n the same f i s h . 47 F i g u r e 4. Rubidium c o n c e n t r a t i o n s i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k h e l d onshore over sand and mud s u b s t r a t e and o f f s h o r e p l o t t e d a g a i n s t dry weight of f i s h . A l l f i s h captured o f f s h o r e . (on=held onshore, o f f = h e l d o f f s h o r e ) . F i s h were h e l d f o r 40 days from May 26th to J u l y 4th, 1984. Sample s i z e s a r e , j u v e n i l e sockeye h e l d onshore 8, h e l d o f f s h o r e 7; t h r e e s p i n e s t i c k l e b a c k h e l d onshore 8, h e l d o f f s h o r e 5. 48 soc-on n a a. n r r 10000 8000 6000 4000 2000 soc-off 0.0D 0.02 0.04 0.06 0.00 0.02 0.04 Q.06 st-on st - o f f 10000 B000 6000 4000 2000 - i i _ 0.00 0.10 0.20 0.30 0.00 0.10 0.20 0.30 d r y wt (g) 49 F i g u r e 5. Cesium c o n c e n t r a t i o n s i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k h e l d onshore and o f f s h o r e p l o t t e d a g a i n s t dry weight of f i s h . A l l f i s h c a p t u r e d o f f s h o r e . (on=held onshore, o f f = h e l d o f f s h o r e ) . F i s h were h e l d f o r 40 days from May 26th to J u l y 4th, 1984. Sample s i z e s a r e , j u v e n i l e sockeye h e l d onshore 8, h e l d o f f s h o r e 7; t h r e e s p i n e s t i c k l e b a c k h e l d onshore 8, h e l d o f f s h o r e 5. soc-on JQ a a. soc-off 0.00 0.02 0.04 0.06 o o° <b -j i t_ 0.00 0.02 0.04 0.06 C_> st-on st - o f f 0.00 0.10 0.20 0.30 0 d r y wt (g) .DO 0.10 0.20 0.30 Table 5. M u l t i p l e comparisons 1 f o r j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k h e l d onshore and o f f s h o r e . A l l f i s h c a p tured o f f s h o r e . Numbers i n margins are group medians. Rb ppb 6400 3800 5800 3300 soc-on st-on s o c - o f f s t - o f f 6400 soc-on 3800 * st-on 3.35 5800 s o c - o f f 3300 * * s t - o f f 4.02 3.27 Cs ppb 450 550 160 410 soc-on st-on s o c - o f f s t - o f f 450 soc-on 550 st-on 160 * * s o c - o f f 2.70 3.80 410 s t - o f f 1 NPMC • s i g n i f i c a n t q s t a t i s t i c , q c r i t i c a l = 2.64, a = 0.05, df=4 (s o c = j u v e n i l e sockeye, st=threespine s t i c k l e b a c k , 6n=held onshore, o f f = h e l d o f f s h o r e ) 52 However, c o n c e n t r a t i o n s of Rb and Cs i n stomach contents were p o l a r i z e d i n t o 2 ranges; high * 1800-19000 ppb Rb, 1000- 1900 ppb Cs and low » 1800-6800 ppb Rb, 500-510 ppb Cs (Table 6). However, only enough m a t e r i a l c o u l d be c o l l e c t e d f o r one composite sample from f i s h h e l d o f f s h o r e . Confinement of f i s h to wire cages d i d not appear to a f f e c t c o n c e n t r a t i o n s of Rb and Cs i n stomach c o n t e n t s . C o n c e n t r a t i o n s of Rb and Cs i n stomach contents of t h r e e s p i n e s t i c k l e b a c k h e l d onshore i n wire cages were not s i g n i f i c a n t l y d i f f e r e n t from the c o n c e n t r a t i o n s found i n stomach co n t e n t s of t h r e e s p i n e s t i c k l e b a c k with f u l l access to the bottom s u b s t r a t e (Mann- Whitney t e s t ; Rb: U=23, P > 0.05; Cs: U=21, P > 0.05, n(1)= 9, n(2) =4). Long-term: t h r e e s p i n e s t i c k l e b a c k As i n the short-term experiment, f i s h m o r t a l i t i e s were not the same among s i t e s . Out of an i n i t i a l s t o c k i n g d e n s i t y of 20 t h r e e s p i n e s t i c k l e b a c k the number of s u r v i v i n g i n d i v i d u a l s were: 13 ( h e l d over sand), 12 ( h e l d over c o b b l e ) , 14 ( h e l d over sand- v.. mud), and 12 ( h e l d over gravel-mud). Subsamples of 8 t h r e e s p i n e s t i c k l e b a c k from each group were used i n the f o l l o w i n g a n a l y s e s . Rubidium and Cs c o n c e n t r a t i o n s i n t h r e e s p i n e s t i c k l e b a c k h e l d over v a r i o u s s u b s t r a t e types were dependent on s i t e ( F i g u r e 6; KW, Rb: H=30.52, Cs: H=26.51, P < 0.05, df=4). F i s h sampled from cages h e l d over sand-mud and gravel-mud s u b s t r a t e had s i g n i f i c a n t l y higher Rb c o n c e n t r a t i o n s than f i s h h e l d over sand and cobble s u b s t r a t e s alone (NPMC, Table 7 ) . Only f i s h h e l d 53 T a b l e 6. C o n c e n t r a t i o n s of Rb and Cs i n stomach c o n t e n t s of j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k h e l d o n s h o r e and o f f s h o r e . A l l f i s h c a p t u r e d o f f s h o r e . Stomach c o n t e n t s of f i s h (n) were p o o l e d b e f o r e a n a l y s i s f o r Rb and Cs c o n c e n t r a t i o n . g r o u p 1 Rb ppb Cs ppb n s t - o n 18000 1900 5 s t - o n 19000 1 1 00 5 s o c - o n 1900 1000 8 s o c - o n 6400 500 8 s t - o n 6800 510 4 s t - o f f 1800 510 7 1 on=held o n s h o r e , o f f = h e l d o f f s h o r e , s o c = j u v e n i l e s o c k e y e , s t = t h r e e s p i n e s t i c k l e b a c k 54 F i g u r e 6. Rubidium and Cs c o n c e n t r a t i o n s i n 4 groups of t h r e e s p i n e s t i c k l e b a c k h e l d over v a r i o u s s u b s t r a t e s and one group captured offshore.. Numbers i n p a r e n t h e s i s are sample s i z e s . F i s h were h e l d f o r 266 days from August 4th, 1984 to A p r i l 28th, 1985. A long h o r i z o n t a l l i n e i s drawn through the median of the data. The upper and lower extremes of the t h i c k v e r t i c a l l i n e represent the upper and lower q u a r t i l e s . The upper end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the l a r g e s t o b s e r v a t i o n t h a t i s l e s s than or equal to the upper q u a r t i l e p l u s 1.5 x the i n t e r q u a r t i l e range. The lower end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the s m a l l e s t o b s e r v a t i o n that i s g r e a t e r than or equal to the lower q u a r t i l e minus 1.5 x the i n t e r q u a r t i l e range. A l l v a l u e s o u t s i d e the upper and lower extremes of the t h i n v e r t i c a l l i n e are p l o t t e d as "*". 1985. 55 8Q00 7 0 0 0 6 0 0 0 JO D. a 5 0 0 0 JQ rx 4 0 0 0 3 0 0 0 2 0 0 0 5 0 0 0 4 0 0 0 - n 3 0 0 0 a a U) u 2 0 0 0 1000 0 - l (8} 2 (B) 3 (7) 4 (8) 5 (B) s i t e 56 Table 7. M u l t i p l e comparisons 1 f o r t h r e e s p i n e s t i c k l e b a c k from long term h o l d i n g experiment. Number i n margins are group medians. Rb ppb sand 31 50 cobble 3700 sand (mud) 7100 g r a v e l (mud) 6800 o f f s h o r e 4200 sand 3150 cobble 3700 sand (mud) 7100 * 4.58 * 3.71 g r a v e l (mud) 6800 * 3.80 * 2.98 of fs h o r e 4200 * 2.94 1NPMC • s i g n i f i c a n t q v a l u e s , q c r i t i c a l =2.81, a = 0.05, df=5 57 over sand-mud s u b s t r a t e were s i g n i f i c a n t l y higher i n Rb c o n c e n t r a t i o n s compared to f i s h c a ptured o f f s h o r e (Table 7). Cs c o n c e n t r a t i o n s d i d not f o l l o w the same a s s o c i a t i o n s of s i g n i f i c a n t comparisons and s u b s t r a t e types as Rb. The only s i g n i f i c a n t comparisons f o r Cs were between f i s h h e l d over sand and cobble with higher c o n c e n t r a t i o n s than f i s h captured o f f s h o r e (NPMC, Table 8 ) . The dry weights of stomach co n t e n t s were too small to determine c o n c e n t r a t i o n s of Rb and Cs. 58 Table 8 . M u l t i p l e comparisons 1 f o r t h r e e s p i n e s t i c k l e b a c k from long-term h o l d i n g experiment. Numbers i n margins are group medians. Cs ppb sand cobble sand g r a v e l o f f s h o r e (mud) (mud) 2100 2500 1500 1400 390 sand 2100 cobble 2500 sand (mud) 1500 g r a v e l (mud) 1400 o f f s h o r e * * 390 3.48 5.00 1 NPMC • s i g n i f i c a n t q v a l u e s , q c r i t i c a l = 2.81, a = 0.05, df = 5 59 D i s c u s s i o n : short-term and long-term experiments In i n both the short-term and the long-term experiment t h r e e s p i n e s t i c k l e b a c k h e l d over a s u b s t r a t e of sand and mud were not s i g n i f i c a n t l y d i f f e r e n t i n Cs c o n c e n t r a t i o n s compared to t h r e e s p i n e s t i c k l e b a c k h e l d o f f s h o r e or captured o f f s h o r e r e s p e c t i v e l y . However, the long-term experiment demonstrated that such a c o n c l u s i o n was dependent on the type of s u b s t r a t e over which t h r e e s p i n e s t i c k l e b a c k were h e l d . The exact f e a t u r e s of sand and cobble s u b s t r a t e s i t e s t h a t r e s u l t e d i n higher Cs c o n c e n t r a t i o n s i n t h r e e s p i n e s t i c k l e b a c k h e l d onshore compared to t h r e e s p i n e s t i c k l e b a c k captured o f f s h o r e was not known. Since c o n c e n t r a t i o n s of Rb and Cs i n f i s h are d e r i v e d from i n g e s t e d foods (Fleishman 1973), e l e v a t e d c o n c e n t r a t i o n s of Cs must be r e l a t e d to d i f f e r e n c e s i n prey. K a n e v s k i i and Fleishman (1972) r e p o r t e d higher c o n c e n t r a t i o n s of Cs i n t h r e e s p i n e s t i c k l e b a c k compared to j u v e n i l e sockeye and a t t r i b u t e d the l a t t e r to the presence of benthos and zooplankton i n the d i e t of t h r e e s p i n e s t i c k l e b a c k and only zooplankton i n the d i e t of j u v e n i l e sockeye. In the Hudson R i v e r e s t u a r y , c o n c e n t r a t i o n s of Cs-137 were 3 to 4 times higher i n bottom feeders compared to open water feeders (McDonald et a l . 1971). I t should be noted that i n the short-term experiment no s i g n i f i c a n t d i f f e r e n c e was observed between t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye h e l d onshore. The l a c k of a s i g n i f i c a n t d i f f e r e n c e does not appear a t t r i b u t a b l e to the cage r e s t r i c t i n g access to the 60 s u b s t r a t e . Threespine s t i c k l e b a c k allowed f u l l access to a s u b s t r a t e c o n s i s t i n g of sand and mud were not s i g n i f i c a n t l y d i f f e r e n t i n Rb and Cs c o n c e n t r a t i o n s compared to f i s h h e l d i n wire cages over the same s u b s t r a t e . I t cannot be c o n c l u s i v e l y s t a t e d that the higher c o n c e n t r a t i o n s of Cs observed i n both the sho r t and long-term experiments was due to the i n c l u s i o n of benthos i n the d i e t . Although K a n e v s k i i and Fleishman (1972) s t a t e d that the measurement of Rb and Cs appeared e s p e c i a l l y u s e f u l where the d i r e c t i n v e s t i g a t i o n of d i e t was extremely d i f f i c u l t , there appears to be . a need to examine stomach c o n t e n t s where i n f o r m a t i o n beyond u t i l i z a t i o n of d i f f e r e n t h a b i t a t s i s d e s i r e d . In the short-term experiment, j u v e n i l e sockeye were s i g n i f i c a n t l y d i f f e r e n t i n Cs c o n c e n t r a t i o n s when h e l d over a s u b s t r a t e c o n s i s t i n g of sand and mud compared to j u v e n i l e sockeye h e l d o f f s h o r e . The reason f o r t h i s s p e c i e s d i f f e r e n c e was not e v i d e n t . In a review of f e e d i n g behavior of t h r e e s p i n e s t i c k l e b a c k , Wootton (1976) c i t e s the presences of benthic prey in the d i e t of t h r e e s p i n e s t i c k l e b a c k . Examination of f e e d i n g behavior of both t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye over a s u b s t r a t e c o n s i s t i n g of sand and mud, would be r e q u i r e d to r e s o l v e t h i s d i f f e r e n c e i n d i e t based on Cs c o n c e n t r a t i o n s . There appears to be l i t t l e i n f o r m a t i o n i n the l i t e r a t u r e c o n c e r n i n g Rb c o n c e n t r a t i o n s i n f i s h . In the short-term experiment, t h r e e s p i n e s t i c k l e b a c k h e l d over s u b s t r a t e c o n s i s t i n g of sand and mud were not s i g n i f i c a n t l y d i f f e r e n t compared to t h r e e s p i n e s t i c k l e b a c k h e l d o f f s h o r e . However, i n 61 the long-term experiment t h r e e s p i n e s t i c k l e b a c k h e l d over the same s u b s t r a t e type were s i g n i f i c a n t l y d i f f e r e n t i n Rb c o n c e n t r a t i o n s compared to t h r e e s p i n e s t i c k l e b a c k captured o f f s h o r e . K a n e v s k i i and Fleishman (1972) r e p o r t e d lower c o n c e n t r a t i o n s of Rb i n t h r e e s p i n e s t i c k l e b a c k having f ed on benthos compared to j u v e n i l e sockeye having fed on zooplankton. Whether t h i s h o l d true i n Kennedy Lake was not e s t a b l i s h e d . C o n c e n t r a t i o n s of Rb and Cs i n stomach contents from f i s h h e l d onshore and o f f s h o r e i n the short-term experiment were s i m i l a r to those i n the uptake experiments (Chapter 2 ) . F i s h fed a Cs e n r i c h e d zooplankton mix had hig h and low c o n c e n t r a t i o n s of Cs i n stomach c o n t e n t s . The same p a t t e r n was observed i n the short-term experiment. These r e s u l t s once again suggest that f i s h were s e l e c t i n g d i f f e r e n t prey items that e i t h e r v a r i e d i n t h e i r c o n c e n t r a t i o n s of Cs or were not e q u a l l y d i g e s t i b l e by f i s h . The same set of experiments as proposed i n Chapter 2 would serve e q u a l l y w e l l i n the present case towards r e s o l v i n g the observed v a r i a t i o n s i n Cs c o n c e n t r a t i o n s i n stomach c o n t e n t s . In c o n c l u s i o n , higher c o n c e n t r a t i o n s of Rb and Cs were observed when f i s h were c o n f i n e d t o the l i t t o r a l area of Kennedy Lake but r e s u l t s were dependent on type of s u b s t r a t e over which f i s h were h e l d , and s p e c i e s of f i s h compared. Measurement of Rb and Cs i n stomach contents and f i s h t i s s u e s was i n s u f f i c i e n t to determine what changes i n d i e t r e s u l t e d i n w i t h i n or between s p e c i e s d i f f e r e n c e s i n t i s s u e c o n c e n t r a t i o n s of Rb and cesium. However, i n a l l cases where s i g n i f i c a n t d i f f e r e n c e s i n Rb and Cs 62 c o n c e n t r a t i o n s were d e t e c t e d between f i s h h e l d onshore and f i s h h e l d or captured o f f s h o r e , higher c o n c e n t r a t i o n s of Rb and Cs were a s s o c i a t e d with onshore s i t e s . 63 CHAPTER 4 In t e r a n n u a l v a r i a t i o n i n Rb and Cs c o n c e n t r a t i o n s i n water, zooplankton, and f i s h I n t r o d u c t i o n Seasonal changes i n the c o n c e n t r a t i o n s of Rb and Cs i n water and zooplankton i n freshwater lakes have a p p a r e n t l y escaped a t t e n t i o n i n the l i t e r a t u r e . R e p r e s e n t a t i v e v a l u e s f o r Rb and Cs i n freshwater have been rep o r t e d by Coughtrey and Thorne (1983) as 1.4 ppb f o r Rb and 0.05 ppb f o r Cs. C o n c e n t r a t i o n s of Rb and Cs i n water and phytoplankton of the Columbia R i v e r i n November were 3.5 ppb Rb, 0.035 ppb Cs f o r water, and 69.0 ppb Rb, 2.11 ppb Cs f o r phytoplankton (Cushing 1 979) . Input of s t a b l e Rb and Cs to freshwaters has a l s o a p p a r e n t l y escaped a t t e n t i o n , though geology of the drainage b a s i n can be expected to i n f l u e n c e c o n c e n t r a t i o n s i n o v e r l y i n g waters. Input of Cs i n the form of atmospheric f a l l o u t of Cs- 137 has been r e p o r t e d to have a seasonal high i n the s p r i n g , f r e q u e n t l y with a second h i g h i n the f a l l (Hannerz 1968). F a l l o u t of Cs-137 as r e p o r t e d by Hannerz (1968) was dependent on l a t i t u d e with a maximum at 45°N. C o n s i d e r a b l e amounts of Cs-137 may accumulate with snow and be subsequently r e l e a s e d i n the s p r i n g (Nelson and Whicker 1969, G a l l e g o s 1970). 64 Seasonal highs i n the c o n c e n t r a t i o n s of Cs-137 i n the organisms of a smal l a q u a t i c community were noted by Pendleton (1962), but cor r e s p o n d i n g dates and c o n c e n t r a t i o n s were not g i v e n . H a s l e r and Like n s (1963) observed that a q u a t i c midges Chaoborus and Chironomus sp. removed d e t e c t a b l e amounts of r a d i o a c t i v i t y when they emerged as a d u l t s . B i o l o g i c a l h a l f - l i v e s f o r Cs-137 of 5 days and 7 days have been given f o r zooplankton and i n s e c t l a r v a e r e s p e c t i v e l y (Coughtrey and Thorne 1983). Both groups of organisms would appear to r e f l e c t r a p i d changes i n ambient cesium. Seasonal changes i n the balance of Cs-137 and s t a b l e Cs i n b l u e g i l l s have been i n v e s t i g a t e d i n White Oak Lake, Tennessee, by Kolehmainen (1972). Both Cs-137 and s t a b l e Cs i n b l u e g i l l s (Leppmis macrochirus) g r e a t e r than 70g i n c r e a s e d to a maximum i n February, and decreased to a minimum i n August. The c y c l i n g of Cs-137 i n stomach co n t e n t s agreed w e l l with the c y c l i n g of Cs- 137 i n b l u e g i l l t i s s u e s . Q u a n t i t i e s of stomach c o n t e n t s were too small f o r s t a b l e Cs a n a l y s i s . The white c r a p p i e (Pomoxis a n n u l a r i s ) i n the C l i n c h River a l s o d i s p l a y e d peak c o n c e n t r a t i o n s of s t a b l e Cs i n e a r l y s p r i n g with minimal v a l u e s d u r i n g the summer (Nelson 1969). In c o n t r a s t largemouth bass (Micropterus salmoides) i n Wintergreen Lake, Michigan had low c o n c e n t r a t i o n s of s t a b l e Cs i n May, maximum c o n c e n t r a t i o n s i n J u l y , and decreased again i n October but at va l u e s g r e a t e r than those observed i n May ( S p i g a r e l l i 1971). C o n c e n t r a t i o n s of Cs- 137 i n largemouth bass d i d not f o l l o w an i d e n t i c a l p a t t e r n to s t a b l e Cs. Cesium-137 was h i g h e s t i n May, decreased i n August 65 and rose again i n October ( S p i g a r e l l i 1971). Although S p i g a r e l l i (1971) r e p o r t e d s i m i l a r p a t t e r n s f o r both s t a b l e Cs and Cs-137 with weight i n largemouth bass, seasonal d i f f e r e n c e s suggested d i f f e r e n t a v a i l a b i l i t i e s of Cs and Cs-137 i n Lake Wintergreen. The seasonal changes r e p o r t e d by S p i g a r e l l i (1971) were i n c o n t r a s t to Kolehmainen (1974) who observed s i m i l a r b e h a v i o r s f o r s t a b l e Cs and Cs-137 in White Oak Lake. In c e r t a i n l a k e s , the d i s p a r i t y i n accumulation p a t t e r n s of s t a b l e Cs and Cs-137 may r e f l e c t atmospheric f a l l o u t of the l a t t e r . Cesium-137 does not occur n a t u r a l l y , being an a r t i f i c i a l i s o t o p e produced from nuclear r e a c t i o n s , and u n l i k e s t a b l e Cs cannot a r i s e from source endogenous to the l a k e i t s e l f or the drainage b a s i n . Input of Cs-137 to d i f f e r e n t l a k e s as atmospheric f a l l o u t may r e f l e c t l o c a l r a i n f a l l , wind p a t t e r n s or p r o x i m i t y to p o i n t sources of Cs-137. Gustafson (1967) observed that c o n c e n t r a t i o n s of Cs-137 i n s m a l l f i s h from Red Lake i n c r e a s e d d u r i n g the summer, i n d i c a t i n g a prime dependence upon t o t a l accumulation of Cs-137 from f a l l o u t . Measurement of Cs- 137 and s t a b l e Cs i n water and food items may r e s o l v e apparent d i f f e r e n c e s between these two i s o t o p e s i n f i s h from c e r t a i n l a k e s . Seasonal s h i f t s i n Rb and Cs c o n c e n t r a t i o n s were of p a r t i c u l a r importance i n the present study, as t h r e e s p i n e s t i c k l e b a c k spawn i n the l i t t o r a l zone of freshwater l a k e s , yet as observed by Burgner (1959), Rogers(1968), and T i l l e r (1974), immatures may occupy the l i m n e t i c zone with j u v e n i l e sockeye. The main o b j e c t i v e of the f o l l o w i n g study was to determine 66 the degree of o v e r l a p i n the use of l i t t o r a l and l i m n e t i c areas of Kennedy Lake on a seasonal b a s i s by j u v e n i l e sockeye and th r e e s p i n e s t i c k l e b a c k . A secondary o b j e c t i v e was to determine i f onshore movement of t h r e e s p i n e s t i c k l e b a c k to breed i n June r e s u l t s i n s i g n i f i c a n t l y d i f f e r e n t Rb and Cs c o n c e n t r a t i o n s i n t h e i r f l e s h compared to j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k which remain o f f s h o r e at the same time of year. Experiments conducted i n Chapter 2 to determine uptake r a t e s of Cs by t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e s o c k e y e ( j u v e n i l e coho used as a model) would p r e d i c t that both s p e c i e s should c l o s e l y t r a c k Rb and Cs c o n c e n t r a t i o n s i n t h e i r prey. T r a n s f e r experiments i n Chapter 3 i n d i c a t e d t h a t e l e v a t e d c o n c e n t r a t i o n s of Rb and Cs c o u l d be a s s o c i a t e d with f e e d i n g onshore but that a l a c k of a c o n t r a s t between s p e c i e s c a p t u r e d onshore and o f f s h o r e would not n e c e s s a r i l y i n d i c a t e t h a t f e e d i n g i n onshore areas had not o c c u r r e d . F i n a l l y , c o n c e n t r a t i o n s of Rb and Cs were monitored i n water and zooplankton. The former was to d e t e c t any marked input of Rb and Cs i n t o the lake d u r i n g May to September 1983, while the l a t t e r was to determine i f changes i n Rb and Cs c o n c e n t r a t i o n s i n zooplankton would r e s u l t i n s i m i l a r responses i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k . 67 M a t e r i a l s and methods J u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k were c o l l e c t e d on May 25th, J u l y 5th, and J u l y 26th, 1983 from Kennedy Lake. F i s h were c a p t u r e d o f f s h o r e by t r a w l i n g and onshore by beach s e i n e . A n a l y s i s f o r Rb and Cs content was performed on groups of 8 f i s h . E i g h t c o n s e c u t i v e zooplankton h a u l s were made at biweekly i n t e r v a l s between May 4th and September 10th, 1983 i n both l a k e s between the hours of 1500h and 2l00h i n areas p r e v i o u s l y t r a w l e d f o r f i s h ( F i g u r e s 7 and 8 ) . S i x c o n s e c u t i v e water samples were taken at biweekly i n t e r v a l s between May 27th and September 10th, 1983 i n both l a k e s i n areas p r e v i o u s l y t r a w l e d f o r f i s h ( F i g u r e s 7 and 8). 68 F i g u r e 7. Map of Kennedy Lake showing s i t e s of water, zooplankton and f i s h c o l l e c t i o n s . KENNEDY LAKE C L A Y O Q U O T ARM 70 F i g u r e 8 . Map of Great C e n t r a l Lake showing s i t e s of water, zooplankton and f i s h c o l l e c t i o n s minnow traps O 72 R e s u l t s Water The c o n c e n t r a t i o n s of Rb and Cs i n water samples from Kennedy and Great C e n t r a l Lake were c h a r a c t e r i z e d by a l a r g e degree of v a r i a b i l i t y among sampling dates ( F i g u r e 9). The d i s t r i b u t i o n s f o r the m a j o r i t y of samples were skewed towards higher c o n c e n t r a t i o n s and median and q u a r t i l e p l o t s ( F i g u r e 10) are a c c o r d i n g l y more meaningful than c o n v e n t i o n a l c o n f i d e n c e l i m i t s . For Rb c o n c e n t r a t i o n s there was a s i g n i f i c a n t i n t e r a c t i o n between la k e s and sampling dates (NPANOVA, H=21.71, P < 0.05, df=5), because there was a s i g n i f i c a n t d i f f e r e n c e i n Rb c o n c e n t r a t i o n s on the l a s t sampling date, Sept. 10 (Figure 9, NPMC, q=3.70, P <0.05, d f = l 2 ) . In l i g h t of these r e s u l t s and the e x c e e d i n g l y l a r g e range of Rb c o n c e n t r a t i o n s on the l a s t date i n Great C e n t r a l Lake, a n a l y s i s was repeated with the l a s t sampling date removed from the NPANOVA d e s i g n . No s i g n i f i c a n t i n t e r a c t i o n between lakes and sampling dates was obt a i n e d u s i n g the reduced model (NPANOVA, H=4.15, P < 0.05, df=4). The reduced model i n d i c a t e d that a s i g n i f i c a n t d i f f e r e n c e among sampling dates (NPANOVA, H=16.57, P < 0.05, df=4), arose from higher c o n c e n t r a t i o n s of Rb on 24 May 27th compared with ~ J u l y 7th and ^ J u l y 27th (NPMC, q=3.54, and q=3.14 r e s p e c t i v e l y , P < 0.05, df=5). For Cs c o n c e n t r a t i o n s there was a s i g n i f i c a n t i n t e r a c t i o n 73 F i g u r e 9 . C o n c e n t r a t i o n s of Rb and Cs i n water samples from Kennedy and Great C e n t r a l Lake p l o t t e d a g a i n s t sampling dates. V e r t i c a l bars r e p r e s e n t 95% c o n f i d e n c e l i m i t s f o r the mean. F i r s t row of numbers below f i g u r e s represent sample s i z e s . 0.20 0.15 h 0. 10 h X Kennedy 0 Great Central X I 0 0.05 x o.o h j i i_ j i i i i i i i u 0.05 0.04 h 0.03 0.02 0.01 0.0 }- 6 6 6 6 6 5 5 6 6 5 6 5 27 6 16 26 6 16 26 5 15 25 4 14 24 May June July Aug Sep d a t e 1983 75 F i g u r e 1 0 . Q u a r t i l e and median p l o t s of Rb and Cs c o n c e n t r a t i o n s i n water f o r data shown i n F i g u r e 9 . Sample s i z e s are given i n F i g u r e 9 . A long h o r i z o n t a l l i n e i s drawn through the median of the d a t a . The upper and lower extremes of the t h i c k v e r t i c a l l i n e r e p r e s e n t the upper and lower q u a r t i l e s . The upper end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the l a r g e s t o b s e r v a t i o n that i s l e s s than or equal to the upper q u a r t i l e p l u s 1 .5 x the i n t e r q u a r t i l e range. The lower end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the s m a l l e s t o b s e r v a t i o n t h a t i s g r e a t e r than or equal to . the lower q u a r t i l e minus 1 .5 x the i n t e r q u a r t i l e range. A l l v a l u e s o u t s i d e the upper and lower extremes of the t h i n v e r t i c a l l i n e are p l o t t e d as "*". 76 n Q. a n 0.25 \- 0.20 0. 15 0 . 10 0.05 0.0 n a. a CJ 0.10 0.08 h 0.06 0.04 0.02 h 0.0 K G K G K G K G K G K G 27 6 16 26 6 16 26 5 15 25 May June J u l y Aug date 1983 4 14 24 Sep 77 between l a k e s and sampling dates (NPANOVA, H=32.36, P < 0.05, df =5), with both the f i r s t and l a s t sampling dates f o r Cs acc o u n t i n g f o r the g r e a t e s t d i f f e r e n c e s between l a k e s ( F i g u r e 9). Nonparametric m u l t i p l e comparisons f a i l e d to d e t e c t a d i f f e r e n c e among i n d i v i d u a l sampling dates. Such a r e s u l t i s probably due to the g r e a t e r power ( power=(1 - 0), p r o b a b i l i t y of a type II e r r o r ) , of the nonparametric a n a l y s i s of v a r i a n c e compared to the m u l t i p l e comparison t e s t . Zooplankton C o n c e n t r a t i o n s of Rb and Cs i n zooplankton were not s i m i l a r to c o n c e n t r a t i o n s of Rb and Cs i n water ( F i g u r e 11). C o n c e n t r a t i o n s were again c h a r a c t e r i z e d by a l a r g e degree of v a r i a b i l i t y among sampling dates ( F i g u r e 11), and median and q u a r t i l e p l o t s ( F i g u r e 12) i n d i c a t e d t hat d i s t r i b u t i o n s were i n most cases skewed towards higher c o n c e n t r a t i o n s . Rb c o n c e n t r a t i o n s were not s i g n i f i c a n t l y d i f f e r e n t between lak e s but t h e r e were s i g n i f i c a n t d i f f e r e n c e s i n sampling dates (NPANOVA; H=21.38, P < 0.05, df=5). Samples taken on ~ June 15 were s i g n i f i c a n t l y higher than those taken on =* J u l y 27th (NPMC, q=8.53, P < 0.05, df=5). Cesium c o n c e n t r a t i o n s i n zooplankton were marked by i n c r e a s e s i n Cs i n Great C e n t r a l Lake on June 17th and J u l y 9th to l e v e l s beyond those observed i n Kennedy Lake on approximately the same date, or i n comparisons with other sampling dates. Remaining samples showed no marked v a r i a t i o n i n Cs c o n c e n t r a t i o n s among dates or l a k e s . 78 F i g u r e 11 . C o n c e n t r a t i o n s of Rb and Cs i n Kennedy and Great C e n t r a l Lake zooplankton p l o t t e d a g a i n s t sampling d a t e s . F i r s t row of numbers below f i g u r e s r epresent sample s i z e s . V e r t i c a l bars are 95 % c o n f i d e n c e l i m i t s on the mean. 10000 r- aooo n BOOO Q. a n O C 4000 2000 r 2000 n Q. a 01 CJ 1500 1000 500 T 0 h J 1 1 1 1 1 I I I I I I I I 6 6 8 6 7 2 8 7 6 8 B 7 4 14 24 3 13 23 3 13 23 2 12 22 1 11 May June Ju l y Aug Sep d a t e 1983 80 F i g u r e 12. Q u a r t i l e and median p l o t s of Rb and Cs c o n c e n t r a t i o n s i n zooplankton from Kennedy and Great C e n t r a l Lake f o r data shown i n F i g u r e 11. Sample s i z e s are given i n F i g u r e 11. A long h o r i z o n t a l l i n e i s drawn through the median of the d a t a . The upper and lower extremes of the t h i c k v e r t i c a l l i n e r epresent the upper and lower q u a r t i l e s . The upper end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the l a r g e s t o b s e r v a t i o n t h a t i s l e s s than or equal to the upper q u a r t i l e p l u s 1.5 x the i n t e r q u a r t i l e range. The lower end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the s m a l l e s t o b s e r v a t i o n that, i s g r e a t e r than or equal to the lower q u a r t i l e minus 1.5 x the i n t e r q u a r t i l e range. A l l v a l u e s o u t s i d e the upper and lower extremes of the t h i n v e r t i c a l l i n e are p l o t t e d as "*". 81 n a a n rr 12000 1000D BQOO 6000 4000 2000 i K Kennedy G Great Central 0 n o. Q. U l U 2000 1500 1000 500 ll U |l ! K K K G K G K G K G K G 4 14 24 3 13 23 3 13 23 2 12 22 1 11 May June J u l y Aug Sep date 1983 82 F i s h The c o n c e n t r a t i o n s of Rb and Cs i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k were c h a r a c t e r i z e d by a l a r g e degree of v a r i a b i l i t y among sampling dates and f i s h ( F i g u r e s 13-14), and median and q u a r t i l e p l o t s ( F i g u r e s 15-16) i n d i c a t e d that i n most cases d i s t r i b u t i o n s were skewed e i t h e r towards l a r g e or small v a l u e s . Rb c o n c e n t r a t i o n s were s i g n i f i c a n t l y d i f f e r e n t among dates (NPANOVA, H=43.40; df=2, P < 0.05), with f i s h sampled on May 25th s i g n i f i c a n t l y higher than f i s h sampled on J u l y 5th and 26th (NPMC q=7.86 and q=8.26 r e s p e c t i v e l y ; P < 0.05, df=<=°,3). J u l y dates were not s i g n i f i c a n t l y d i f f e r e n t from each o t h e r . The c o n c e n t r a t i o n s of Cs i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k demonstrated a s i m i l a r p a t t e r n as f o r Rb, with the exc e p t i o n that j u v e n i l e sockeye captured o f f s h o r e remained at about the same l e v e l of Cs f o r a l l dates ( F i g u r e s 14 and 16). There was a s i g n i f i c a n t i n t e r a c t i o n between f i s h groups and dates f o r Cs c o n c e n t r a t i o n s (NPANOVA, H=11.09, P < 0.05, df=4). J u v e n i l e sockeye sampled on May 25th had s i g n i f i c a n t l y lower Cs c o n c e n t r a t i o n s than e i t h e r group of t h r e e s p i n e s t i c k l e b a c k sampled on the same date ( F i g u r e s 14 and 16, nonparametric S c h e f f e ' s m u l t i p l e c o n t r a s t (Zar, 1984); S=8.41, P < 0.05, n( 1 )=n(2)=n(3)=8). Threespine s t i c k l e b a c k sampled on May 25 had s i g n i f i c a n t l y higher Cs c o n c e n t r a t i o n s than J u l y 5th and 28th samples (S=4.12, P < 0.05, df=8). No other d i f f e r e n c e s were e v i d e n t among groups f o r e i t h e r the J u l y 5th or J u l y 26th sampling dates ( F i g u r e s 15- 16) . 83 Fi g u r e 13. C o n c e n t r a t i o n s of Rb from e a r l y s p r i n g to mid- summer i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Kennedy Lake p l o t t e d a g a i n s t dry weight of f i s h . J u v e n i l e sockeye were captured o f f s h o r e ( o f f ) while t h r e e s p i n e s t i c k l e b a c k were captured o f f s h o r e and onshore (on). Sample s i z e i s 8. 84 7000 B000 5000 4000 3000 2000 1000 n Q . CL n tx 0 . 0 7000 6000 5000 4000 3000 r 2000 1000 0 . 0 7000 6000 5000 4000 3000 2000 1000 s t i c k l e b a c k - o f f oo 4* 0 . 1 s t i c k l e b a c k - o n 0 . 2 Q . 3 o o o 0 . 0 0 . 2 ^ « A - 4> A* • 0 . 4 o • a t e s o c k e y e - o f f o M/D/Y 0 5 2 5 B 3 cft> A 0 7 0 5 B 3 0 • 0 7 2 6 8 3 ° ° ° • • A 1 1 • • 1 • • 0 . 0 5 0 . 1 0 0 . 15 0 . 2 0 0 . 2 5 0 . 3 0 0 . 4 0 . 6 0 . 8 d r y wt (g) 85 F i g u r e 14. C o n c e n t r a t i o n s of Cs from e a r l y s p r i n g t o mid- summer i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Kennedy Lake p l o t t e d a g a i n s t dry weight of f i s h . J u v e n i l e sockeye were captured o f f s h o r e ( o f f ) while t h r e e s p i n e s t i c k l e b a c k were captured o f f s h o r e and onshore (on). Sample s i z e i s 8. 86 1000 800 BOO sockeye-of f •ate M/D/Y o 052583 A 070583 • 072683 400 200 - o 8«o 0 0.0 1000 • A A .A A " A 0.05 0.10 s t i c k l e b a c k - o f f 0. 15 0.20 0.25 0.30 Ci a cn U BOO 600 400 200 o o o o o 0.0 0. 1 0.2 0.3 0 . 4 1000 800 600 400 200 s t i c k l e b a c k - o n o • AAA A A O.Q 0.2 0.4 0.6 0.8 d r y wt (g) 87 F i g u r e 15. Q u a r t i l e and median p l o t s of Rb c o n c e n t r a t i o n s i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k f o r data i n F i g u r e 13. Sample s i z e i s 8. A long h o r i z o n t a l l i n e i s drawn through the median of the data. The upper and lower extremes of the t h i c k v e r t i c a l l i n e r e p r e s e n t the upper and lower q u a r t i l e s . The upper end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the l a r g e s t o b s e r v a t i o n that i s l e s s than or equal to the upper q u a r t i l e p l u s 1.5 x the i n t e r q u a r t i l e range. The lower end o f - t h e t h i n v e r t i c a l l i n e i s d e f i n e d t o be the s m a l l e s t o b s e r v a t i o n that i s g r e a t e r than or equal to the lower . q u a r t i l e minus 1.5 x the i n t e r q u a r t i l e range. A l l v a l u e s o u t s i d e the upper and lower extremes of the t h i n v e r t i c a l l i n e are p l o t t e d as "*". 60Q0 5000 4000 3000 r 2000 1000 s o c k e y e - o f f 6000 5000 4000 3000 2000 h 1000 s t i c k l e b a c k - o f f 1 1 6000 5000 4000 3000 2000 1000 * s t i c k l e b a c k - o n 052583 070583 072683 dates M/D/Y 89 F i g u r e 16. Q u a r t i l e and median p l o t s of Cs c o n c e n t r a t i o n s i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k f o r data i n F i g u r e 14. Sample s i z e i s 8. A long h o r i z o n t a l l i n e i s drawn through the median of the data. The upper and lower extremes of the t h i c k v e r t i c a l l i n e represent the upper and lower q u a r t i l e s . The upper end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the l a r g e s t o b s e r v a t i o n that i s l e s s than or equal to the upper q u a r t i l e p l u s 1.5 x the i n t e r q u a r t i l e range. The lower end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the s m a l l e s t o b s e r v a t i o n that i s g r e a t e r than or equal to the lower q u a r t i l e minus 1.5 x the i n t e r q u a r t i l e range. A l l v a l u e s o u t s i d e the upper and lower extremes of the t h i n v e r t i c a l l i n e are p l o t t e d as "*". 1000 800 600 400 - 200 - 0 x "I" s o c k e y e - o f f 1 1000 800 600 400 200 0 s t i c k l e b a c k - Q f f 0 5 2 5 8 3 0 7 0 5 8 3 d a t e s M/D/Y 0 7 2 6 8 3 91 The c o n c e n t r a t i o n of Rb and Cs i n the stomach contents of j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k c o u l d not be determined on a l l sampling dates due to low sample weights. The c o n c e n t r a t i o n s that were obtained were i n g e n e r a l agreement with a decrease i n both Rb and Cs c o n c e n t r a t i o n s i n t h r e e s p i n e s t i c k l e b a c k from May 25th to J u l y 26th, 1983 (Table 9 ) . 92 Table 9. C o n c e n t r a t i o n of Rb and Cs i n stomach contents of j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Kennedy l a k e . Each value r e p r e s e n t s an a n a l y s i s performed on the pooled stomach contents of e i g h t f i s h . Date M/D/Y sockeye o f f s h o r e 1 Rb (ppb) Cs s t i c k l e b a c k o f f s h o r e 1 Rb (ppb) Cs s t i c k l e b a c k onshore 1 Rb (ppb) Cs 052583 070583 072883 1 400 1 300 2100 73 133 235 2800 4000 1 400 1 300 1 500 2400 340 3600 330 660 4000 750 3400 700 90 2800 130 1 40 280 160 2800 130 1 400 150 1200 220 1800 67 1 s i t e of capture 93 Di s c u s s i o n Springtime i n both Kennedy and Great C e n t r a l Lake was a s s o c i a t e d with heavy r a i n f a l l and m e l t i n g of snow as water l e v e l s rose i n t o the surrounding shrubs and t r e e s along the s h o r e l i n e . E l e v a t e d c o n c e n t r a t i o n s of Rb and p o s s i b l y Cs i n the month of May appear to be a s s o c i a t e d with t h i s o ccurrence. Nelson and Whicker (1969) mention p o s s i b l e c o n t r i b u t i o n s of Cs- 137 from m e l t i n g snow banks su r r o u n d i n g montane and a l p i n e l a k e s . However, i t i s not known whether content of Cs-137 v a r i e s i n snow with e l e v a t i o n , as both Kennedy and Great C e n t r a l are c o a s t a l l a k e s . Cesium i s p a r t i c u l a r l y w e l l bound by s o i l (Davis 1963), and e r o s i o n a l p r o c e s s e s a s s o c i a t e d with h i g h water l e v e l s i n Kennedy and Great C e n t r a l Lake were c l e a r l y v i s i b l e along the s h o r e l i n e i n 1983. Of note, water from Kennedy and Great C e n t r a l Lake was not f i l t e r e d to remove suspended s o l i d s . Rubidium and Cs c o n c e n t r a t i o n may i n c r e a s e i n the f a l l when heavy r a i n s occur once again i n both areas of Kennedy and Great C e n t r a l Lake, but data were i n s u f f i c i e n t to c o n f i r m t h i s s u p p o s i t i o n . C o n c e n t r a t i o n s of Rb and Cs i n zooplankton d i d not d i r e c t l y r e f l e c t water c o n c e n t r a t i o n s . Zooplankton absorb l i t t l e Cs-137 d i r e c t l y from water, food being the primary source ( W i l l i a m s and P i c k e r i n g 1961, King 1964). The i n t e r m e d i a t e step of Rb and Cs from water to food sources may have dampened the appearance of s i m i l a r seasonal trends i n water and zooplankton. In a d d i t i o n , 94 water samples were assessed f o r t o t a l Rb and Cs, and would i n c l u d e f r a c t i o n s of the l a t t e r which would be t i g h t l y bound to p a r t i c u l a t e matter that may not be as r e a d i l y a v a i l a b l e to b i o t a as the s o l u b l e f r a c t i o n . E l e v a t e d c o n c e n t r a t i o n s of Rb and Cs i n June, and Cs i n J u l y i n Great C e n t r a l Lake may p o s s i b l y be r e l a t e d to the presence of Holopedium qibberum. T h i s s p e c i e s was i n s u f f i c i e n t numbers to s e r i o u s l y impede the flow of water through the zooplankton net. Kolehmainen et a l . (1968a) draw p a r t i c u l a r a t t e n t i o n to t h i s s p e c i e s and i t s "90% s l i m e " , content as a f a c t o r r e n d e r i n g comparisons of s t a b l e elements w i t h i n l a k e s and between years more d i f f i c u l t . Presumably t h i s " s l i m e " r e s u l t s i n e i t h e r higher or lower c o n c e n t r a t i o n s of t r a c e elements compared with other zooplankton s p e c i e s , but t h i s aspect was not addressed by the a u t h o r s . S e p a r a t i o n of zooplankton s p e c i e s f o r subsequent t r a c e metal a n a l y s i s would appear to be hindered by the l a r g e number of organisms r e q u i r e d to reach a sample weight w i t h i n d e t e c t i o n l i m i t s . In a 1977-1978 survey of Great C e n t r a l Lake by Rankin et a l . (1979), the most abundant s p e c i e s (over 10% of average a d u l t zooplankton abundance), were: Cyclops b i c u s p i d a t u s , Bosmina c o r e q o n i , and Holopedium qibberum. In c o n t r a s t , the same authors r e p o r t e d the most abundant s p e c i e s i n Kennedy Lake as: Cyclops b i c u s p i d a t u s , Diaptomus oregonensis, Bosmina c o r e q o n i , and Sida c r y s t a l l i n a . In Kennedy Lake, Holopedium gibberum was r a r e . Comparisons of j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k i n Kennedy Lake would appear to be unhindered by sudden s h i f t s i n Rb and Cs c o n c e n t r a t i o n s i n the 95 p o t e n t i a l food base as was observed i n Great C e n t r a l Lake. T h i s r e s u l t does not negate p o s s i b l e s e l e c t i o n of prey items by f i s h t h a t may be h i g h i n Rb and Cs but s u f f i c i e n t l y low i n numbers so as not to s e r i o u s l y a l t e r the mean c o n c e n t r a t i o n s of Rb and Cs in zooplankton. However, such an occurrence i n zooplankton would be l i k e l y marked by an i n c r e a s e i n v a r i a n c e of samples. In t h i s r e s p e c t Kennedy Lake appeared q u i t e uniform, while Great C e n t r a l Lake was s u b j e c t to g r e a t e r sample v a r i a t i o n . The great v a r i a b i l i t y i n Rb and Cs c o n c e n t r a t i o n s i n zooplankton i n Great C e n t r a l Lake may make d e t e c t i o n of d i f f e r e n c e s i n body burdens of Rb and Cs among f i s h more d i f f i c u l t . The c o n c e n t r a t i o n s of Cs i n t h r e e s p i n e s t i c k l e b a c k i n Kennedy Lake were marked by a drop from e l e v a t e d c o n c e n t r a t i o n s in May to lower c o n c e n t r a t i o n s i n June and J u l y . Nelson (1969) observed s t r i k i n g l y s i m i l a r decreases i n s t a b l e Cs c o n c e n t r a t i o n s i n white c r a p p i e s (Plomoxis a n n u l a r i s ) i n the C l i n c h R i v e r between s p r i n g and e a r l y summer. C o n c e n t r a t i o n s of Cs i n white c r a p p i e decreased from 16.5 ppb i n A p r i l to 7.59 ppb in May, 0.47 ppb i n June, and 7.88 ppb i n J u l y . Although the abrupt decrease i n Cs i m p l i e d r a p i d e x c r e t i o n by white c r a p p i e , turnover time was more r a p i d than b i o l o g i c a l h a l f - l i v e s determined i n the l a b o r a t o r y (Nelson 1969). No s a t i s f a c t o r y e x p l a n a t i o n f o r the decrease i n s t a b l e Cs c o u l d be found. S p i g a r e l l i (1971) was a l s o f a c e d with e x p l a i n i n g s p r i n g to e a r l y summer decreases i n Cs-137 i n largemouth bass. High c o n c e n t r a t i o n s i n the s p r i n g were p o s s i b l y a s s o c i a t e d with r a i n f a l l and lake t u r n o v e r . A change i n f e e d i n g h a b i t s appeared 96 to e x p l a i n some of the v a r i a b i l i t y d u r i n g summer months, though no d e f i n i t e c o n c l u s i o n c o u l d be reached. The c o n c e n t r a t i o n s of Cs i n j u v e n i l e sockeye i n Kennedy Lake i n May was s i g n i f i c a n t l y lower than c o n c e n t r a t i o n s i n th r e e s p i n e s t i c k l e b a c k on the same date. However, both s p e c i e s in the l i m n e t i c zone i n May feed almost e n t i r e l y on zooplankton (K. D. Hyatt, p e r s . comm.). I t appears u n l i k e l y t h a t t h r e e s p i n e s t i c k l e b a c k caught o f f s h o r e with j u v e n i l e sockeye i n the l a t e evening were m i g r a t i n g onshore d u r i n g the day. Threespine s t i c k l e b a c k of the same s i z e and c o l o r a t i o n as those caught o f f s h o r e were not cap t u r e d i n beach se i n e hauls d u r i n g the day. I t may be proposed that j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k s e l e c t e d d i f f e r e n t zooplankton f r a c t i o n s and that these f r a c t i o n s were d i f f e r e n t i n Rb arid Cs c o n t e n t . C l e a r l y , f u r t h e r advances i n use of Rb and Cs as a technique to de t e c t d i f f e r e n c e s i n d i e t must address i n d i v i d u a l s p e c i e s d i f f e r e n c e i n Rb and Cs content of prey. Contrary to Cs, Rb c o n c e n t r a t i o n s between May and J u l y e x h i b i t e d a s i m i l a r drop i n c o n c e n t r a t i o n s i n both t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye. Why Rb c o n c e n t r a t i o n s behaved d i f f e r e n t l y than Cs was not known. No i n c r e a s e i n Rb or Cs c o n c e n t r a t i o n s was observed i n th r e e s p i n e s t i c k l e b a c k c a p t u r e d onshore i n Kennedy Lake i n J u l y . Cesium uptake experiments i n Chapter 2 demonstrated that j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k should respond to e l e v a t e d c o n c e n t r a t i o n s of Cs i n t h e i r d i e t w i t h i n at l e a s t 8 days. Threespine s t i c k l e b a c k were f i r s t present onshore i n l a t e 97 May and t h e r e f o r e had s u f f i c i e n t time by l a t e J u l y to e q u i l i b r a t e to e x i s t i n g c o n c e n t r a t i o n s of Rb and Cs i n prey. I t appears u n l i k e l y t h a t t h r e e s p i n e s t i c k l e b a c k captured onshore would d i e before enough time had elapsed to r e f l e c t Rb and Cs c o n c e n t r a t i o n s i n food. Wootton (1976) r e p o r t s a r e p r o d u c t i v e c y c l e i n male t h r e e s p i n e s t i c k l e b a c k of at l e a s t s e v e r a l weeks, and t h i s c y c l e may be r e p e a t e d . Gonads may be viewed as a sink f o r Rb and Cs, though t h i s appears u n l i k e l y . Stomach contents of onshore t h r e e s p i n e s t i c k l e b a c k f r e q u e n t l y c o n t a i n e d eggs but no n o t i c e a b l e d i f f e r e n c e i n Rb and Cs c o n c e n t r a t i o n s was noted when compared with gut contents of t h r e e s p i n e s t i c k l e b a c k captured o f f s h o r e . In b l u e g i l l s , l o s s of Cs-137 from gonads was 4.8 % f o r females and 1 % f o r males (Kolehmainen and Nelson 1969). Threespine s t i c k l e b a c k eggs do not appear to be a major sink f o r Rb and cesium. Near s t a r v a t i o n c o n d i t i o n s may however, a f f e c t the d i s t r i b u t i o n of Rb and Cs i n t i s s u e s . Wootton (1976) observed that below a c e r t a i n t h r e s h o l d of food i n t a k e , female t h r e e s p i n e s t i c k l e b a c k were observed to loose weight d u r i n g spawning but i n the presence of abundant food were able to gain weight. The small s i z e of the l i t t o r a l zone i n Kennedy Lake would suggest that t h r e e s p i n e s t i c k l e b a c k spawning onshore may be faced with a s m a l l e r food resource compared to t h r e e s p i n e s t i c k l e b a c k f e e d i n g o f f s h o r e . Changes i n the c o n c e n t r a t i o n s of Rb and Cs i n f i s h from Kennedy Lake may be governed by a number of f a c t o r s . 98 Kolehmainen (1972) observed a decrease i n Cs-137 c o n c e n t r a t i o n s from s p r i n g to e a r l y summer i n b l u e g i l l s , golden s h i n e r s (Notemiqonus c r y s o l e u c a s ) , g i z z a r d shad (Dorosoma cepedianum), and largemouth bass. Kolehmainen (1972) suggested t h a t body burden of Cs-137 was determined by four f a c t o r s 1) a b s o r p t i o n , 2) f e e d i n g r a t e , 3) c o n c e n t r a t i o n s i n food, and 4) e l i m i n a t i o n times. The i n t e r p l a y of these f a c t o r s would appear complex. I n c r e a s i n g temperatures i n Kennedy lake c o r r e l a t e d with decreases i n Rb and Cs i n t h r e e s p i n e s t i c k l e b a c k and decreases in Rb i n j u v e n i l e sockeye. However, d i f f e r e n c e s i n Cs c o n c e n t r a t i o n s between t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye i n May remain u n r e s o l v e d . In c o n c l u s i o n , c o n c e n t r a t i o n s of Rb and Cs i n t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye were not s i m i l a r to zooplankton c o n c e n t r a t i o n s . D i f f e r e n c e s i n Cs c o n c e n t r a t i o n s between th r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye i n May suggested s e l e c t i o n of d i f f e r e n t zooplankton f r a c t i o n s . However, more d e t a i l e d i n v e s t i g a t i o n s w i l l be r e q u i r e d to v a l i d a t e t h i s s p e c u l a t i o n . Presence of t h r e e s p i n e s t i c k l e b a c k onshore to breed d i d not r e s u l t i n higher c o n c e n t r a t i o n s of Rb and Cs i n t h e i r t i s s u e s compared with t h r e e s p i n e s t i c k l e b a c k s captured o f f s h o r e . R e s u l t s from the t r a n s f e r experiments i n Chapter 3 demonstrated that only f e e d i n g over c e r t a i n s u b s t r a t e types r e s u l t e d i n e l e v a t e d c o n c e n t r a t i o n s of Rb and Cs i n f i s h t i s s u e s . Threespine s t i c k l e b a c k i n May may have fed i n areas were e l e v a t e d c o n c e n t r a t i o n s of Rb and Cs were not present i n prey, though t h i s assumption w i l l r e q u i r e f u r t h e r i n v e s t i g a t i o n . 99 CHAPTER 5 D i e t h i s t o r y and c o m p e t i t i o n as indexed by rubidium and cesium I n t r o d u c t i o n A competitor many a f f e c t a second s p e c i e s by: 1) a l t e r i n g i t s d e n s i t y , 2) i n f l u e n c i n g f a c t o r s that might a f f e c t i t s d e n s i t y such as f e c u n d i t y , growth, and m o r t a l i t y , or 3) a f f e c t i n g i t s use of food or h a b i t a t ( C o n n e l l 1983). Johannes and L a r k i n (1961) c i t e a r e d u c t i o n i n numbers, e x t i n c t i o n or em i g r a t i o n . In j u v e n i l e sockeye the e f f e c t s may be as s u b t l e as changes i n s c h o o l i n g d e n s i t y , search range, area of f e e d i n g , and fo o d - s p e c i e s composition (Burgner 1959). F r e q u e n t l y , the e f f e c t s of c o m p e t i t i o n appear to take the form of changes i n h a b i t a t or food p r e f e r e n c e s . Werner and H a l l (1979) were ab l e to demonstrate changes i n h a b i t a t p r e f e r e n c e as a r e s u l t of co m p e t i t i o n among 3 congeneric C e n t r a c h i d a e . Svardson (1949) found a displacement of a r c t i c char S a l v e l i n u s a l p i n u s , from i t s p r e f e r r e d l i t t o r a l h a b i t a t by brown t r o u t Salmo t r u t t a . N i l s s o n (1958) pres e n t s evidence f o r g r e a t e r divergence i n food or h a b i t a t p r e f e r e n c e i n two s p e c i e s of Coregonus when they occur t o g e t h e r . The i n t e n s i t y of comp e t i t i o n appears to f l u c t u a t e c o n s i d e r a b l y with changes i n resource a v a i l a b i l i t y and p o p u l a t i o n l e v e l s , p a r t i c u l a r l y i n seasonal environments (Werner and H a l l , 1979). Indeed, the 100 f o r e g o i n g f a c t o r s o f t e n generate the c o n d i t i o n s t h a t l e a d to the s u p p o s i t i o n that some form of i n t e r a c t i o n i s t a k i n g p l a c e . C o n d i t i o n s a f t e r the change has o c c u r r e d i n the environment may however, obscure past i n t e r a c t i o n s between f i s h (Johannes and L a r k i n 1961).. The d e t e c t i o n of c o m p e t i t i o n between j u v e n i l e sockeye and other s p e c i e s would on a s u p e r f i c i a l b a s i s appear q u i t e f e a s i b l e due to l a r g e f l u c t u a t i o n s i n the abundance of the former. However, sockeye producing l a k e s can be host to a l a r g e number of s p e c i e s ( F o e r s t e r 1968), and resource a v a i l a b i l i t y may be d i f f i c u l t to a s s e s s or h i g h l y v a r i a b l e . The so c a l l e d "competing s p e c i e s " may escape a r i g i d d e f i n i t i o n of c o m p e t i t i o n , as a r e s u l t of an i n a b i l i t y on the p a r t of the i n v e s t i g a t o r to demonstrate a demand f o r the same resources i n excess of the immediate supply. The l a t t e r i s a s t r i c t component of the d e f i n i t i o n of c o m p e t i t i o n as proposed by L a r k i n (1956). Hence a more c a u t i o u s approach has been adopted by Greenbank and Nelson (1959), Krogius and Krokhin (1956), Ruggles(1965), Rogers (1968), and Markovtsev (1973) where p o t e n t i a l c o m p e t i t i o n between t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye f o r food has been only suggested. Among the p o t e n t i a l competitors with j u v e n i l e sockeye, t h r e e s p i n e s t i c k l e b a c k have r e c e i v e d widespread a t t e n t i o n . Other s p e c i e s mentioned by F o e r s t e r (1968) appear r e g i o n a l i n t h e i r impact, but more e x t e n s i v e i n v e s t i g a t i o n may be r e q u i r e d . For i n s t a n c e , F o e r s t e r (1968) mentions the occurrence of the pond smelt (Hypomesus o l i d u s ) and n i n e s p i n e s t i c k l e b a c k 101 ( P u n g i t i u s p u n g i t i u s ) i n Kamchatka, e a s t e r n w h i t e f i s h (Coregonus c l u p e a f o r m i s ) i n Morrison Lake, and a l e u t i a n s c u l p i n s (Cottus a l e u t i c u s ) and u n s p e c i f i e d minnows i n C u l t u s Lake. Hartman and Burgner (1972) a l s o note the presence of the ni n e s p i n e s t i c k l e b a c k as a p o t e n t i a l competitor with young sockeye i n Lake Nerka and Lake Dalnee. Markovtsev (1973) re p o r t e d the presence of 3 s p e c i e s of f i s h i n the p e l a g i c zone of Lake Dalnee, j u v e n i l e sockeye, a r c t i c char ( S a l v e l i n u s a l p i n u s ) , and t h r e e s p i n e s t i c k l e b a c k . Sockeye were c l a s s i f i e d as zooplankton e a t e r s w h ile t h r e e s p i n e s t i c k l e b a c k were o p t i o n a l benthos e a t e r s . The p e r i o d of g r e a t e s t s i m i l a r i t y i n d i e t i n the l a t t e r was d u r i n g the summer months, with g r e a t e s t o v e r l a p i n the p e l a g i c zone i n c o n t r a s t to the l i t t o r a l zone. In Lake Dalnee, t h r e e s p i n e s t i c k l e b a c k of ages 1+ and 2+ remained i n the p e l a g i c zone while mature f i s h moved i n t o the l i t t o r a l zone to spawn (Markovtsev 1973). Krogius et a l . (1969), r e p o r t e d f o r a g i n g e x c u r s i o n s of 3 year o l d t h r e e s p i n e s t i c k l e b a c k i n t o the l i m n e t i c zone of Lake Dalnee d u r i n g the spawning season. In the Wood R i v e r Lakes, t h r e e s p i n e s t i c k l e b a c k appeared to l i v e 3 years and occupied the l i t t o r a l alone i n the s p r i n g with j u v e n i l e sockeye (Rogers 1968). Both s p e c i e s moved i n t o the l i m n e t i c zone about mid-July (Rogers 1968). In the l i t t o r a l zone of lower Lake Aleknagik, p a r t of the Wood R i v e r l a k e s ; midge f l y l a r v a e , pupae, c y c l o p o i d copepods, i n s e c t s , and cru s t a c e a n s were important to both s p e c i e s , with . g r e a t e r occurrence of winged i n s e c t s i n the d i e t of j u v e n i l e sockeye. 102 In t h r e e s p i n e s t i c k l e b a c k i n the l i t t o r a l zone, d i e t was s i m i l a r to j u v e n i l e sockeye but t h r e e s p i n e s t i c k l e b a c k eggs and p l a n t m a t e r i a l s were a l s o p a r t of the d i e t , and winged i n s e c t s were not important (Rogers 1968). In c e r t a i n c a t c h e s of t h r e e s p i n e s t i c k l e b a c k i n the l i t t o r a l zone of Lake Aleknagik an abundance of copepods i n the stomach contents suggested f e e d i n g at deeper l e v e l s i n the lake (Rogers 1968). S i m i l a r e x c u r s i o n s of mature t h r e e s p i n e s t i c k l e b a c k i n t o the l i m n e t i c zone as observed i n Lake Dalnee by Markovtsev (1973) may be suggested by t h i s r e s u l t . Rogers (1968) concluded that based on the a v a i l a b l e data i t was not p o s s i b l e to estimate the amount of food eaten by the t h r e e s p i n e p o p u l a t i o n that would have been u t i l i z e d by the sockeye f r y p o p u l a t i o n i n the absence of the l a t t e r . I t i s of i n t e r e s t to note that t h r e e s p i n e s t i c k l e b a c k have a l s o been c i t e d as a p o t e n t i a l competitor with j u v e n i l e a t l a n t i c salmon (Salmo s a l a r ) . Ryan (1984) observed that t h r e e s p i n e s t i c k l e b a c k i n Headwater and Spruce Ponds, Newfoundland, consumed ben t h i c c l a d o c e r a n s and chironomid l a r v a e , while those i n nearby L i t t l e G u l l Lake consumed p e l a g i c daphnids and bosminids. Ryan (1984) concluded t h a t o n l y a s m a l l part of the food resource was shared between t h r e e s p i n e s t i c k l e b a c k s and j u v e n i l e a t l a n t i c salmon. T h i s f l e x i b i l i t y i n t h r e e s p i n e s t i c k l e b a c k may a l s o extend to h a b i t a t s e p a r a t i o n i n c e r t a i n l a k e s . In a study by Manzer (1976) t h r e e s p i n e s t i c k l e b a c k i n Great C e n t r a l Lake were second i n abundance to j u v e n i l e sockeye salmon. Both s p e c i e s fed on s i m i l a r organisms, n e v e r t h e l e s s , c o m p e t i t i o n was judged as not 103 s e r i o u s as t h r e e s p i n e s t i c k l e b a c k were r a r e l y captured i n the l i m n e t i c zone where sockeye were almost the e x c l u s i v e i n h a b i t a n t s . However, l a r g e r t h r e e s p i n e s t i c k l e b a c k were l e s s a v a i l a b l e i n the l i t t o r a l zone d u r i n g the day i n midsummer and f a l l . Although not a c o n c l u s i o n drawn by Manzer (1976), the e x i s t e n c e of f o r a g i n g e x c u r s i o n s i n t o the p e l a g i c zone may have o c c u r r e d as suggested e a r l i e r f o r Lake Dalnee (Krogius et a l . 1969 ) and the Wood River Lakes (Rogers 1968). Perhaps i n lakes with l i m i t e d l i t t o r a l a rea, food r e s o u r c e s become exhausted and f i s h must forage o f f s h o r e p e r i o d i c a l l y . T hreespine s t i c k l e b a c k i n C u l t u s Lake, B r i t i s h Columbia a l s o appear r e s t r i c t e d to l i t t o r a l areas of the l a k e . In a review by F o e r s t e r (1968) t h r e e s p i n e s t i c k l e b a c k i n C u l t u s Lake were viewed as only i n f r i n g i n g on the l a t e r a l borders of the food supply of j u v e n i l e sockeye salmon. The degree of i n t e r a c t i o n between j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k appears v a r i a b l e both w i t h i n and among l a k e s . A n a l y s i s of Rb and Cs i n f i s h from one lake cannot be c o n s i d e r e d r e p r e s e n t a t i v e of p a t t e r n s i n other l a k e s . The c o n c e n t r a t i o n s of Rb and Cs were t h e r e f o r e determined i n both t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye salmon i n two l a k e s where t h r e e s p i n e s t i c k l e b a c k o c c u r r e d i n both the l i m n e t i c and l i t t o r a l zone, Kennedy and Lake Aleknagik, and i n two l a k e s i n which t h r e e s p i n e s t i c k l e b a c k appeared r e s t r i c t e d to the l i t t o r a l zone, Great C e n t r a l and C u l t u s Lake. I t was p o s t u l a t e d that Rb and Cs c o n c e n t r a t i o n s would r e f l e c t the d i f f e r e n t h a b i t a t s s e l e c t e d by onshore-benthic-consumers and o f f s h o r e - p l a n k t o n - 104 consumers, and would c o n t r a s t i n the two groups of l a k e s mentioned above. Threespine s t i c k l e b a c k a l s o d i s p l a y v a r i a b i l i t y i n the form of two m o r p h o l o g i c a l l y d i s t i n c t s p e c i e s , r e f e r r e d to as l i m n e t i c and b e n t h i c s by Bentzen and McPhail (1984). These authors found that i n f i s h from Enos Lake, B r i t i s h Columbia, the benthic form d i s p l a y e d an a f f i n i t y f o r f e e d i n g over bottom sediments and the l i m n e t i c form an a f f i n i t y f o r f e e d i n g i n the open water column. T h i s s p e c i e s p a i r was i d e a l l y s u i t e d f o r e x p l o r a t i o n of d i e t u s i n g Rb and Cs c o n c e n t r a t i o n s as a t a g . C u l t u s Lake c o n t a i n s a r a t h e r d i v e r s e f i s h community which i n c l u d e s j u v e n i l e sockeye ( F o e r s t e r 1968). The lake was an i d e a l model f o r e x p l o r i n g d i e t i n f i s h s p e c i e s other than t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye. Included i n t h i s community are r e d s i d e s h i n e r s ( R i c h a r d s o n i u s b a l t e a t u s ) , peamouth chub ( M y l o c h e i l u s c a u r i n u s ) , p r i c k l y s c u l p i n (Cottus a s p e r ) , and squawfish ( P t y c h o c h e i l u s o r e g o n e n s i s ) . The d i e t s of a l l of these s p e c i e s have been c i t e d by S c o t t and Crossman (1973) and F o e r s t e r (1968). As i n d i c a t e d by these authors, l a r g e r e d s i d e s h i n e r s consume a d i v e r s e number of food items i n c l u d i n g a l g a e , mollusks, f i s h eggs, s m a l l f i s h , and t h e i r own eggs, but are mainly i n s e c t i v o r o u s consuming immature forms of most a q u a t i c i n s e c t s . Peamouth chub consume almost i d e n t i c a l food items to r e d s i d e s h i n e r s with the a d d i t i o n of a wide v a r i e t y of p l a n k t o n i c c r u s t a c e a n s . Large p r i c k l y s c u l p i n consume a v a r i e t y of items such as f i s h eggs, young of t h e i r own as w e l l as other s p e c i e s i n c l u d i n g sockeye salmon. Squawfish 105 over 10cm i n l e n g t h , consume mainly f i s h but i n c l u d e t e r r e s t r i a l i n s e c t s ' and some plan k t o n . More s p e c i f i c a l l y d u r i n g May to September i n C u l t u s Lake squawfish have been observed to consume s h i n e r s and t h r e e s p i n e s t i c k l e b a c k ( F o e r s t e r 1968). In c o n c l u s i o n , s i n c e t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye vary i n t h e i r use of h a b i t a t s , uptake p a t t e r n s of Rb and Cs were examined i n Great C e n t r a l , C u l t u s , and Lake Aleknagik, l a k e s i n which co m p e t i t i o n between these s p e c i e s has been suggested. Enos Lake was examined as a smal l lake i n which two d i s t i n c t v a r i e t i e s of s t i c k l e b a c k s d i s p l a y d i s t i n c t f e e d i n g h a b i t s , one b e t t e r at f o r a g i n g over s u b s t r a t e s , the other i n the open water column. Whether Rb and Cs c o u l d be used to d e t e c t t h i s d i f f e r e n c e i n f e e d i n g h a b i t s was e v a l u a t e d . C u l t u s Lake was examined as a sockeye producing lake c o n t a i n i n g both p i s c i v o r o u s and i n s e c t i v o r o u s f i s h . T h i s lake was examined to determine i f Rb and Cs c o n c e n t r a t i o n s c o u l d be used to d e t e c t a d i f f e r e n c e i n d i e t between these two groups. The a b i l i t y to d i s t i n g u i s h h a b i t a t u t i l i z a t i o n p a t t e r n s u s i n g Rb and Cs c o n c e n t r a t i o n s i n these lakes and i n a s s o c i a t i o n s other than t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye was e s s e n t i a l i n dete r m i n i n g the method's u t i l i t y and r e l i a b i l i t y . 1 06 M a t e r i a l s and methods S e c t i o n 1: Sympatric s t i c k l e b a c k s ( E n o s Lake) S t i c k l e b a c k s were c o l l e c t e d by beach seine from Enos Lake on June 6, 1985. F i s h were d i v i d e d i n t o benthic and l i m n e t i c forms of both sexes a c c o r d i n g to c r i t e r i a o u t l i n e d by McPhail (1984). The benthic form of s t i c k l e b a c k was captured by beach s e i n e i n c l o s e p r o x i m i t y to the s h o r e l i n e (l-2m), while the l i m n e t i c form was captured by an extended sweep of the beach seine to a d i s t a n c e of approximately 6m. F i s h and stomach contents were ana l y z e d f o r Rb and Cs c o n c e n t r a t i o n s . A n a l y s i s was performed on groups of 8 f i s h . 107 R e s u l t s The c o n c e n t r a t i o n s of Rb and Cs, i n accordance with sex and form, were h i g h l y v a r i a b l e among groups ( F i g u r e s 17-18). Co n c e n t r a t i o n s of Rb and Cs were s i g n i f i c a n t l y d i f f e r e n t among groups (KW, Rb: H=12.86, Cs: H=21.86, P < 0.05, df=3), with benthic males having s i g n i f i c a n t l y higher Rb c o n c e n t r a t i o n s than benthic females (NPMC, q=5.0l, P < 0.05, df=<»,4), and benth i c females having s i g n i f i c a n t l y higher Cs c o n c e n t r a t i o n s than l i m n e t i c females and l i m n e t i c males (NPMC, q=6.l5 and q=4.88, r e s p e c t i v e l y , df=»,4; P < 0.05). The c o n c e n t r a t i o n s of Rb i n stomach contents were not i n t o t a l agreement with observed d i f f e r e n c e s among the f i s h themselves (Table 10). The c o n c e n t r a t i o n s of Rb were h i g h e s t i n ben t h i c females not bent h i c males. In c o n t r a s t , the c o n c e n t r a t i o n s of Cs d i d not c o n f l i c t with p a t t e r n s observed i n the f i s h themselves. The measurement of c o n c e n t r a t i o n s of Rb and Cs i n stomach co n t e n t s of a l l f i s h were hampered by low sample weights. 108 F i g u r e 17. C o n c e n t r a t i o n s of Rb i n t h r e e s p i n e s t i c k l e b a c k from Enos Lake p l o t t e d a g a i n s t dry weight of f i s h . Sample s i z e i s 8. 109 b e n t h i c m a l e s l i m n e t i c m a l e s n a a n 8000 6000 4000 2000 b e n t h i c f e m a l e s 8000 6000 4000 2000 o o° o o o -1 I I l_ 0.00 0.20 0.40 0.60 0.00 0.10 0.20 0.30 l i m n e t i c f e m a l e s 0.00 0.20 0.40 0.60 0.00 0.03 0.06 0.09 d r y wt (g) 1 10 F i g u r e 18. C o n c e n t r a t i o n s of Cs i n t h r e e s p i n e s t i c k l e b a c k from Enos Lake p l o t t e d a g a i n s t dry weight of f i s h . Sample s i z e i s 8. Ill b e n t h i c m a l e s l i m n e t i c m a l e s 3000 2500 2000 1500 1000 500 J Q Q . D . 0.00 0.20 0.40 0.60 0.00 0.10 0.20 0.30 CO CJ b e n t h i c f e m a l e s l i m n e t i c f e m a l e s 3000 2500 2000 1500 1000 500 0.00 0.20 0.40 0.60 0.00 0.03 0.06 0.09 d r y wt (g) Table 10. C o n c e n t r a t i o n s of Rb and Cs i n stomach contents of t h r e e s p i n e s t i c k l e b a c k from Enos l a k e . Stomach contents i n each group(8) were pooled p r i o r to a n a l y s i s . s t i c k l e b a c k Rb(ppb) Cs(ppb) male (benthic) 4800 78~0 female (benthic) 6100 700 male ( l i t t o r a l ) 6000 700 female ( l i t t o r a l ) 2400 680 1 1 3 D i s c u s s i o n Bentzen and McPhail (1984) found no d i f f e r e n c e i n the f o r a g i n g a b i l i t i e s of b e n t h i c males and females on a n a t u r a l s u b s t r a t e . In c o n t r a s t , Rb c o n c e n t r a t i o n s i n b e n t h i c males were s i g n i f i c a n t l y higher than i n benthic females, though no d i f f e r e n c e i n Cs c o n c e n t r a t i o n s was found i n the same f i s h . The c o n c e n t r a t i o n s of Rb were high e r i n benthic males compared to b e n t h i c females. The r e s u l t s from the long-term experiment i n Chapter 3 i n d i c a t e d t h at Cs c o n c e n t r a t i o n s i n t h r e e s p i n e s t i c k l e b a c k d i d not vary s i g n i f i c a n t l y when f i s h were h e l d over sand, cobble, sand(mud), or gravel(mud) s u b s t r a t e s . However, s i g n i f i c a n t l y higher Rb c o n c e n t r a t i o n s were found i n f i s h having fed over sand(mud) and gravel(mud) s u b s t r a t e s as opposed to sand and cobble a l o n e . The d i f f e r e n c e s i n Rb c o n c e n t r a t i o n s between bent h i c males and females may be e x p l a i n e d by occupation of mud a s s o c i a t e d s u b s t r a t e s by b e n t h i c males. Benthic males defend a t e r r i t o r y around t h e i r nest s i t e from i n t r u d i n g females and other males (Wootton 1976). In Enos Lake, the nest s i t e s of benthic males are predominantly i n patches of v e g e t a t i o n while those of l i m n e t i c males are i n more open areas (D. McPhail p e r s . comm,). The long-term h o l d i n g experiment i n d i c a t e d that of the two mud a s s o c i a t e d s u b s t r a t e s , only the gravel(mud) s u b s t r a t e d i d not r e s u l t i n higher Rb c o n c e n t r a t i o n s i n t h r e e s p i n e s t i c k l e b a c k s compared with f i s h c a p t u r e d o f f s h o r e . The p r e v i o u s p r e d i c t i o n of occupation of mud a s s o c i a t e d s u b s t r a t e s by benthic males may be f u r t h e r r e f i n e d to 1 1 4 gravel(mud) s u b s t r a t e s , as benthic males were not s i g n i f i c a n t l y d i f f e r e n t i n Rb c o n c e n t r a t i o n s compared with l i m n e t i c males. Benthic females would have been r e s t r i c t e d to f e e d i n g over sand and cobble type s u b s t r a t e s . In the long-term experiment, only t h r e e s p i n e s t i c k l e b a c k h e l d over sand and cobble s u b s t r a t e s alone, possessed higher Cs c o n c e n t r a t i o n s compared to t h r e e s p i n e s t i c k l e b a c k captured o f f s h o r e . In Enos Lake s t i c k l e b a c k s , only benthic females were s i g n i f i c a n t l y d i f f e r e n t from l i m n e t i c males and l i m n e t i c females i n Cs c o n c e n t r a t i o n s . Present r e s u l t s would suggest that the a b i l i t y of Rb and Cs to d e t e c t d i f f e r e n c e s i n onshore and o f f s h o r e u t i l i z a t i o n p a t t e r n s depends on the type of s u b s t r a t e over which f i s h have fed and how long they have fed i n that a r e a . D i f f e r e n t onshore h a b i t a t u t i l i z a t i o n p a t t e r n s i n Enos Lake would not c o n f l i c t with the o b s e r v a t i o n s of Bentzen and McPhail (1984) that b e n t h i c s t i c k l e b a c k d i s p l a y b e t t e r f o r a g i n g a b i l i t i e s than l i m n e t i c s t i c k l e b a c k on a n a t u r a l s u b s t r a t e . The c o n c e n t r a t i o n s of Cs i n stomach contents of Enos Lake s t i c k l e b a c k s d i d not d i s a g r e e with the r e s u l t s i n f i s h , though such was not the case f o r Rb. However, stomach contents do not r e f l e c t the longer p e r i o d of Rb and Cs accumulation i n f i s h . 1 15 M a t e r i a l s and methods S e c t i o n 2: J u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k H a b i t a t u t i l i z a t i o n p a t t e r n s as indexed by Rb and Cs c o n c e n t r a t i o n s f o r j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k were examined i n Kennedy, Great C e n t r a l , C u l t u s , Babine, and Lake Al e k n a g i k . One or more of the f o l l o w i n g were sampled: sockeye f r y , sockeye smolts or t h r e e s p i n e s t i c k l e b a c k s Sampling dates were: a) Kennedy Lake- May 25th, 1983, b) Great C e n t r a l Lake - May 27th, 1983, c) Lake Aleknagik - J u l y 18th, 1983, d) Babine Lake - May 29th, 1985, and e) C u l t u s Lake - May 15th, 1985. A l l f i s h were ca p t u r e d by beach seine or midwater t r a w l with.the e x c e p t i o n of smolts from Babine Lake which were captured at a c o u n t i n g fence on the Babine R i v e r . F i s h were d i v i d e d a c c o r d i n g to t h e i r r e s p e c t i v e groupings and a n a l y z e d f o r both Rb and Cs c o n c e n t r a t i o n s i n f l e s h . A n a l y s i s was performed on groups of 8 f i s h . 1 16 R e s u l t s Smolts C u l t u s Lake y i e l d e d l a r g e s i l v e r c o l o u r e d sockeye salmon i n both midwater t r a w l catches (caught with s m a l l e r sockeye f r y ) and onshore i n beach se i n e h a u l s ( no sockeye f r y i n any of the c a t c h e s ) . Both groups from C u l t u s Lake were of low i n d i v i d u a l sample weights compared to Kennedy and Babine Lake smolts ( F i g u r e s 19 - 21). Both 1 year and 2 year sockeye smolt migrants have been recorded from C u l t u s Lake ( F o e r s t e r 1929). The t o t a l l e ngths of 1 year and 2 year sockeye smolts r e p o r t e d by F o e r s t e r (1929) are presented with the t o t a l l e n g t h s of sockeye ( e x c l u d i n g f r y ) , captured i n C u l t u s Lake i n the s p r i n g of 1985 (Table 11). The mean lengths of both groups captured i n 1985 agreed w e l l with lengths r e p o r t e d f o r 2 year migrants i n t h e i r 1st year by F o e r s t e r (1929). On t h i s b a s i s i t was concluded that sockeye captured i n C u l t u s Lake on May 15th, 1985 were r e s i d e n t f i s h f o r at l e a s t 1 more year and were a c c o r d i n g l y l a b e l l e d as 1+ f i s h . The c o n c e n t r a t i o n s of Rb i n 1+ sockeye c a p t u r e d onshore i n C u l t u s Lake were s i g n i f i c a n t l y higher than 1+ sockeye captured o f f s h o r e on the same date (KW, Rb: H=6.353, 0.01 < P < 0.05, df=1, n=8, median of onshore sample 1000 ppb, median of onshore sample 810 ppb). Cesium c o n c e n t r a t i o n s were not s i g n i f i c a n t l y d i f f e r e n t between these two groups (KW, H=3,048, P > 0.05, df=1,n=8). 1 1 7 F i g u r e 19. C o n c e n t r a t i o n s of Rb i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Kennedy and C u l t u s Lake p l o t t e d a g a i n s t dry weight of f i s h . (soc=sockeye, st=threespine s t i c k l e b a c k , on=captured onshore, off = c a p t u r e d o f f s h o r e , 1+ = f i s h r e s i d e n t f o r at l e a s t 1 more year i n the l a k e ) . Sample s i z e i s 8. 8000 6000 4000 2000 r 0 8000 6000 4000 2000 S Kennedy l a k e A A O A + soc f r y e t - o f f aoc-amolta C u l t u s l a k e o aoc f r y B aoc-on 1+ + aoc-off 1+ A at-on A AA fe + + B 0.0 0.1 0.2 0.3 0.4 0.5 0.6 dry wt (g) 119 F i g u r e 20. C o n c e n t r a t i o n s of Cs i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Kennedy and C u l t u s Lake p l o t t e d a g a i n s t dry weight of f i s h . (soc=sockeye, st= t h r e e s p i n e s t i c k l e b a c k , on=captured onshore, o f f = c a p t u r e d o f f s h o r e , 1+ = f i s h r e s i d e n t f o r at l e a s t 1 more year i n the l a k e ) . Sample s i z e i s 8. 120 Kennedy l a k e 1400 n Q . Q . tn u 0 soc f r y 1200 A s t - o f f + soc smolts 1000 BOO 600 400 200 0 1400 1200 1000 800 - 600 - 400 - 200 - 0 7 8> O soc f r y - A A st-on B soc-on 1+ + s o c - o f f 1+ + + +" A C u l t u s l a k e + *• + HA * + + L_ 0.0 0.1 0.2 0.3 0.4 0.5 0.6 dry wt (g) 121 F i g u r e 21. C o n c e n t r a t i o n s of Kennedy and Babine Lake f i s h . Sample s i z e i s 8 Rb and Cs i n sockeye smolts from p l o t t e d a g a i n s t dry weight of 1 0 0 0 0 8 0 0 0 n 6 0 0 0 a a £ 4 0 0 0 2 0 0 0 0 1 0 0 0 8 0 0 n 6 0 0 a a ui u 4 0 0 2 0 0 o Kennsdy X Bablna mj X X X X x X X X 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . d r y wt (g) 0 Table 11. T o t a l l engths of 1yr and 2yr sockeye migrants i n t h e i r f i r s t year as r e p o r t e d by F o e r s t e r (1929) f o r C u l t u s Lake compared wi t h j u v e n i l e sockeye captured from C u l t u s Lake on May 15th, 1985. Category mean standard d e v i a t i o n c o e f f i c e n t l e n g t h mm mm of v a r i a t i o n 1 yr migrants 1 82.4 5.3 1 5.68 2yr migrants 1 58.5 3.0 19.76 t r a w l 2 48 3 16.0 s e i n e 2 52 9 6.7 1 F o e r s t e r (1929), based on s c a l e readings 2 T h i s study 124 C o n c e n t r a t i o n s of Rb and Cs were s i g n i f i c a n t l y d i f f e r e n t among smolts from Kennedy and Babine Lake, and 1+ sockeye caught o f f s h o r e i n C u l t u s Lake (KW, H=19.62, P < 0.05, df=2), with higher c o n c e n t r a t i o n s of Rb and Cs i n f i s h from Kennedy and Babine Lake compared to C u l t u s Lake (NPMC, Table 12). Con t r a s t of Kennedy and C u l t u s Lake: sockeye f r y , sockeye smolts, ,1+ sockeye and t h r e e s p i n e s t i c k l e b a c k In comparing both Kennedy and C u l t u s Lake, t h r e e groups of f i s h were c o n s i d e r e d ; sockeye y e a r l i n g s ( i n c l u d e s 1+ sockeye caught o f f s h o r e i n C u l t u s and sockeye smolts from Kennedy), sockeye f r y from both l a k e s , and t h r e e s p i n e s t i c k l e b a c k c a p t u r e d o f f s h o r e i n Kennedy Lake and onshore i n C u l t u s Lake ( F i g u r e 22). Rubidium c o n c e n t r a t i o n s i n la k e s were s i g n i f i c a n t l y d i f f e r e n t (NPANOVA; l a k e s , H=35.13, P < 0.05, d f = l ) , with higher c o n c e n t r a t i o n s i n Kennedy Lake than C u l t u s Lake. A s i g n i f i c a n t i n t e r a c t i o n between la k e s and f i s h groups was observed f o r Cs c o n c e n t r a t i o n s (NPANOVA F i g u r e 22; H=9.50, P < 0.05, df =2). Within group comparisons i n d i c a t e d s i g n i f i c a n t l y h i g h e r Cs c o n c e n t r a t i o n s i n Kennedy Lake smolts than C u l t u s Lake 1+ sockeye and Kennedy Lake f r y , and i n C u l t u s Lake t h r e e s p i n e s t i c k l e b a c k than C u l t u s Lake 1+ sockeye ( F i g u r e 22, NPMC, q=4.94, q=4.60, q=4.09, r e s p e c t i v e l y ; P< 0.05, df=°°,6). An important c o n t r a s t between the two lak e s l i e s i n the comparison of C u l t u s Lake 1+ sockeye and Kennedy Lake sockeye smolts. Although both groups of f i s h have experienced a Table 12. M u l t i p l e comparisons 1 among c o n c e n t r a t i o n s of Rb and Cs i n Kennedy smolts, Babine smolts, and 1+ sockeye from C u l t u s Lake. Rb ppb - Kennedy 5900 Babine 4800 C u l t u s 810 Kennedy 5900 Babine 4800 Cu l t u s 810 * 6.25 * .3.52 Cs ppb Kennedy 430 Babine 280 C u l t u s 1 30 Kennedy 430 Babine 280 Cu l t u s * * 130 5.15 3.32 1 NPMC * s i g n i f i c a n t l y d i f f e r e n t q v a l u e s , q c r i t i c a l = 3.31 a = 0.05, df=°°,3 126 F i g u r e 22. Q u a r t i l e and median p l o t s of Rb and Cs c o n c e n t r a t i o n s i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Kennedy and C u l t u s Lake. (codes: 1 to 3 Kennedy Lake, sockeye f r y captured o f f s h o r e , t h r e e s p i n e s t i c k l e b a c k c a p t u r e d o f f s h o r e , sockeye smolts ca p t u r e d o f f s h o r e ; 4 to 7 C u l t u s Lake, sockeye f r y ca p t u r e d o f f s h o r e , t h r e e s p i n e s t i c k l e b a c k captured onshore, 1+ sockeye c a p t u r e d o f f s h o r e and 1+ sockeye ca p t u r e d onshore). Sample s i z e i s 8. A long h o r i z o n t a l l i n e i s drawn through the median of the data. The upper and lower extremes of the t h i c k v e r t i c a l l i n e r e p r e s e n t the upper and lower q u a r t i l e s . The upper end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the l a r g e s t o b s e r v a t i o n that i s l e s s than or equal to the upper q u a r t i l e p l u s 1.5 x the i n t e r q u a r t i l e range. The lower end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the s m a l l e s t o b s e r v a t i o n t h a t i s g r e a t e r than or equal to the lower q u a r t i l e minus 1.5 x the i n t e r q u a r t i l e range. A l l v a l u e s o u t s i d e the upper and lower extremes of the t h i n v e r t i c a l l i n e are p l o t t e d as "*". 3 4 5 6 7 K C c • c • 8 c 1 1 m + a + 0 0 8 1 a c t a t a 0 8 c 0 0 c • f n • 0 f f 0 f n f f g r o u p i n g s 128 s i m i l a r e l a p s e of time from h a t c h i n g w i t h i n t h e i r r e s p e c t i v e lakes they d i f f e r i n Cs c o n c e n t r a t i o n s . J u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k c o n t r a s t among lakes Kennedy Lake samples were composed of t h r e e s p i n e s t i c k l e b a c k c a p t u r e d o f f s h o r e and onshore but j u v e n i l e sockeye were only c a p t u r e d o f f s h o r e . Threespine s t i c k l e b a c k captured onshore were breeding f i s h . C u l t u s Lake samples were composed of t h r e e s p i n e s t i c k l e b a c k captured onshore and j u v e n i l e sockeye captured both onshore and o f f s h o r e . T h r e e s p i n e s t i c k l e b a c k captured onshore were breeding f i s h . No t h r e e s p i n e s t i c k l e b a c k were ca p t u r e d i n o f f s h o r e t r a w l s i n C u l t u s Lake but sampling was r e s t r i c t e d t o one evening o n l y . Great C e n t r a l Lake samples were composed of t h r e e s p i n e s t i c k l e b a c k captured onshore and j u v e n i l e sockeye c a p t u r e d o f f s h o r e . Threespine s t i c k l e b a c k captured onshore were breeding f i s h . Only one t r a w l d u r i n g the e n t i r e p e r i o d of sampling Great C e n t r a l Lake y i e l d e d t h r e e s p i n e s t i c k l e b a c k (two f i s h ) . J u v e n i l e sockeye were never caught i n beach s e i n e s h a u l s i n Great C e n t r a l Lake. Lake Aleknagik samples were composed of j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k c a p t u r e d both o f f s h o r e and onshore. Threespine s t i c k l e b a c k captured onshore were not marked by the presence of breeding c o l o u r s or mature gonads at the time of sampling. C o n c e n t r a t i o n s of Cs i n Lake Aleknagik samples ( F i g u r e s 23 and 24), were s i g n i f i c a n t l y d i f f e r e n t among groups (KW, H=19.53, P < 0.05, df=3), with higher c o n c e n t r a t i o n s i n t h r e e s p i n e 1 29 F i g u r e 23. C o n c e n t r a t i o n s of Rb p l o t t e d a g a i n s t dry weight of f i s h f o r j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k captured onshore and o f f s h o r e i n Lake A l e k n a g i k . ( s o c = j u v e n i l e sockeye, st=threespine s t i c k l e b a c k , on=captured onshore, off=captured o f f s h o r e ) Sample s i z e i s 8. 130 soc-on s o c - o f f JQ a a n m 10000 8000 6000 4000 2000 10000 8000 6000 4000 2000 0.0 0.10 0.20 0.30 0.0 0.10 0.20 0.30 S t - O f f s t - o n o o o o • • i — i — i — i — " 0.0 0.10 0.20 0.30 0.0 0.10 0.20 0.30 dry wt (g) 131 F i g u r e 24. C o n c e n t r a t i o n s of Cs p l o t t e d a g a i n s t dry weight of f i s h f o r j u v e n i l e sockeye captured and t h r e e s p i n e s t i c k l e b a c k c a p t u r e d onshore and o f f s h o r e i n Lake Ale k n a g i k . ( s o c = j u v e n i l e sockeye, s t = t h r e e s p i n e s t i c k l e b a c k , on=captured onshore, o f f = c a p t u r e d o f f s h o r e ) Sample s i z e i s 8. 132 soc-on n a a w u 400 300 200 100 soc-off U 1 1 1 ' 1 L l L i , 1 ,1 0.0 0.10 0.20 0.30 0.0 0.10 0.20 0.30 st-on 400 300 200 100 st - o f f 0.0 0.10 0.20 0.30 0.0 Q.io 0.20 0.30 d r y wt (g) 133 s t i c k l e b a c k captured o f f s h o r e and onshore (medians 360 ppb, 300 ppb, r e s p e c t i v e l y ) than j u v e n i l e sockeye captured onshore (median 170 ppb), (NPMC, q=5.59, q=4.70, r e s p e c t i v e l y , P < 0.05, df=°»,4). C o n c e n t r a t i o n s of Rb i n Lake Aleknagik samples were not s i g n i f i c a n t l y d i f f e r e n t ( F igure 23; Kw:H=5.213, df=3, P > 0.05). Si n c e a l l l a k e s y i e l d e d j u v e n i l e sockeye c a p t u r e d o f f s h o r e and t h r e e s p i n e s t i c k l e b a c k captured onshore, these groups were chosen f o r among lake comparisons of Rb and Cs c o n c e n t r a t i o n s ( F i g u r e s 25 - 28). Rb c o n c e n t r a t i o n s were s i g n i f i c a n t l y d i f f e r e n t among l a k e s (NPANOVA; H=37.71, P < 0.05, df=3), with C u l t u s Lake having lower c o n c e n t r a t i o n s than Kennedy, Great C e n t r a l and Lake Aleknagik (NPMC, Table 13). For Cs c o n c e n t r a t i o n s a s i g n i f i c a n t d i f f e r e n c e was found among s p e c i e s and l a k e s (NPANOVA, s p e c i e s : H=26.24, P < 0.05, df=1, l a k e s : H=14.66, p < 0.05, df=3), with t h r e e s p i n e s t i c k l e b a c k s c a p t u r e d onshore having higher c o n c e n t r a t i o n s than j u v e n i l e sockeye captured o f f s h o r e , and Great C e n t r a l Lake having higher c o n c e n t r a t i o n s than Kennedy, C u l t u s , and Lake Aleknagik (NPMC, Table 14). Sin c e Cs c o n c e n t r a t i o n s were s i g n i f i c a n t l y d i f f e r e n t among lakes an a d d i t i o n a l comparison of rank d i f f e r e n c e s between j u v e n i l e sockeye and th r e e s p i n e s t i c k l e b a c k w i t h i n each lake was undertaken (Table 15). Des p i t e a f o u r f o l d d i f f e r e n c e , nonparametric S c h e f f e ' s t e s t f a i l e d to d e t e c t a s i g n i f i c a n t d i f f e r e n c e . 134 Fi g u r e 25. C o n c e n t r a t i o n s of Rb p l o t t e d a g a i n s t dry weight of f i s h f o r j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Kennedy, C u l t u s , Great C e n t r a l and Lake A l e k n a g i k . Numbers below lake names are dates(M/D/Y). (symbols: c i r c l e = j u v e n i l e sockeye captured o f f s h o r e , t r i a n g l e = t h r e e s p i n e s t i c k l e b a c k captured o f f s h o r e , p l u s = t h r e e s p i n e s t i c k l e b a c k captured onshore, and square=juvenile sockeye captured onshore. Sample s i z e i s 8. Kennedy (Q52583J . 7000 6000 Great C e n t r a l (052783) 7000 6000 Cu 1 tus' (051585) Aleknagik (071883) 0.0 0.2 0.4 0.6 0.B 1.0 0.0 0.1 0.2 0 dry wt (g) 1 36 F i g u r e 26. Q u a r t i l e and median p l o t s of Rb c o n c e n t r a t i o n s i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Kennedy, C u l t u s , Great C e n t r a l and Lake A l e k n a g i k . Numbers below lake names are dates (M/D/Y). (codes: 1=juvenile sockeye captured o f f s h o r e , 2=threespine s t i c k l e b a c k c a p t u r e d onshore, 3=threespine s t i c k l e b a c k c a p t u r e d o f f s h o r e , and 4=juvenile sockeye c a p t u r e d onshore). Sample s i z e i s 8. A long h o r i z o n t a l l i n e i s drawn through the median of the d a t a . The upper and lower extremes of the t h i c k v e r t i c a l l i n e r e p r e s e n t the upper and lower q u a r t i l e s . The upper end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the l a r g e s t o b s e r v a t i o n that i s l e s s than or equal to the upper q u a r t i l e p l u s 1.5 x the i n t e r q u a r t i l e range. The lower end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the s m a l l e s t o b s e r v a t i o n t h a t i s g r e a t e r than or equal to the lower q u a r t i l e minus 1.5 x the i n t e r q u a r t i l e range. A l l val u e s o u t s i d e the upper and lower extremes of the t h i n v e r t i c a l l i n e are p l o t t e d as "*". Kennedy (052583) Great C e n t r a l (052783) Cu l t u s (051585) Aleknagik (071883) group ings 138 F i g u r e 27. C o n c e n t r a t i o n s of Cs p l o t t e d a g a i n s t s dry weight of f i s h f o r j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Kennedy, C u l t u s , Great C e n t r a l and Lake Al e k n a g i k . Numbers below lake names are dates(M/D/Y). (symbols: c i r c l e = j u v e n i l e sockeye captured o f f s h o r e , t r i a n g l e = t h r e e s p i n e s t i c k l e b a c k c a p t u r e d o f f s h o r e , p l u s = t h r e e s p i n e s t i c k l e b a c k captured onshore, and square=juvenile sockeye captured onshore. Sample s i z e i s e i g t h . 139 Kennedy 1400 (052583) 1200 - 1000 - 800 600 + . A . A A + A 400 - 200 pp b 0 i i i i i Great C e n t r a l CJ 1400 (052783) 1200 + + + 1000 -o + + + + 800 _o + 600 400 "o c? rs 200 -8 0 i i i i i i C u l t u s (051585) Aleknagik (071883) 0.Q 0.2 0.4 0.6 0.8 1.0 0.0 0.1 0.2 0.3 0.4 dry wt (g) 140 F i g u r e 28. Q u a r t i l e and median p l o t s of Cs c o n c e n t r a t i o n s i n j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k from Kennedy, C u l t u s , Great C e n t r a l and Lake A l e k n a g i k . Numbers below lake names are dates (M/D/Y). (codes: 1=juvenile sockeye captured o f f s h o r e , 2=threespine s t i c k l e b a c k captured onshore, 3=threespine s t i c k l e b a c k c a p t u r e d o f f s h o r e , and 4=juvenile sockeye captured ons h o r e ) . Sample s i z e i s 8. A long h o r i z o n t a l l i n e i s drawn through the median of the data. The upper and lower extremes of the t h i c k v e r t i c a l l i n e represent the upper and lower q u a r t i l e s . The upper end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the l a r g e s t o b s e r v a t i o n that i s l e s s than or equal to the upper q u a r t i l e p l u s 1.5 x the i n t e r q u a r t i l e range. The lower end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the s m a l l e s t o b s e r v a t i o n that i s g r e a t e r than or equal to the lower q u a r t i l e minus 1.5 x the i n t e r q u a r t i l e range. A l l v a l u e s o u t s i d e the upper and lower extremes of the t h i n v e r t i c a l l i n e are p l o t t e d as "*". 141 n a. a m CJ Kennedy (052583) Great C e n t r a l (052783) Cu l t u s (051585) Aleknagik (071883) group ings Table 13. M u l t i p l e comparisons 1 of Rb c o n c e n t r a t i o n s i n f i s h f o r Kennedy, C u l t u s , Great C e n t r a l and Lake A l e k n a g i k . Numbers i n margins are medians. Rb ppb Kennedy 3400 C u l t u s 1 100 Great Aleknagik C e n t r a l 2900 3000 Kennedy 3400 C u l t u s 1 100 * 8.24 Great C e n t r a l 2900 * 4.00 * 4.24 Aleknagi k 3000 * 4.65 1 NPMC * s i g n i f i c a n t l y = 0.05, df=»,4 d i f f e r e n t q v a l u e s , q c r i t i c a l = 3.63, a 143 Table 14. M u l t i p l e comparisons 1 of Cs c o n c e n t r a t i o n s f o r Kennedy, C u l t u s , Great C e n t r a l and Lake Ale k n a g i k . Numbers i n margins are medians. Cs ppb Kennedy 390 C u l t u s Great C e n t r a l 200 880 A l e k n a g i k 260 Kennedy 390 C u l t u s 200 Great C e n t r a l * 880 4.17 * 4.88 Aleknagik 260 * 5.17 1 NPMC • s i g n i f i c a n t l y d i f f e r e n t = 0.05, df=«,4 q v a l u e s , q c r i t i c a l = 3.63, a Table 15. The a b s o l u t e d i f f e r e n c e between rank means w i t h i n l a k e s f o r t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye. Lake |sockeye rank - s t i c k l e b a c k rank | = Kennedy 7.75 1 48.88 41.13 C u l t u s 14.19 - 35.88 21.69 Great C e n t r a l 36.88 - 58.56 21.69 Aleknagik 23.50 - 34.38 10.88 1 45 Di s c u s s i o n F o e r s t e r (1929) mentions three o v e r l a p p i n g l e n g t h groups of sockeye from C u l t u s Lake. One group of l a r g e average s i z e remains i n the lake to mature mainly t h a t same autumn. A second group, i n t e r m e d i a t e i n s i z e , goes d i r e c t l y to sea. The t h i r d group, s m a l l i n s i z e , remains i n the l a k e f o r s e v e r a l y e a r s ; some migrate as 3 year o l d s , while o t h e r s remain i n the lake and mature at ages 3 and 4. Members of t h i s t h i r d group appear to comprise the 1984 sample of j u v e n i l e sockeye other than f r y . Aging would have been more c o n c l u s i v e than l e n g t h r e l a t i o n s h i p s , but the s i g n i f i c a n c e of s m a l l e r l e n g t h s was d e t e c t e d only a f t e r f i s h , had been ground. F o e r s t e r (1968) observed that r e s i d e n t f i n g e r l i n g s moved i n t o the shallow r e g i o n s of the lake before m i g r a t i o n . Based on t h i s study r e s i d e n t sockeye f o r at l e a s t one more year may a l s o move onshore f o r a p e r i o d of time but not migrate. The 1+ sockeye that were c a p t u r e d onshore had s i g n i f i c a n t l y higher Rb c o n c e n t r a t i o n s but not Cs c o n c e n t r a t i o n s when compared to the 1+ sockeye that were ca p t u r e d o f f s h o r e . Perhaps of g r e a t e r i n t e r e s t , Rb and Cs c o n c e n t r a t i o n s i n 1+ sockeye from C u l t u s Lake were lower than i n smolts from Kennedy and Babine Lake. In a d d i t i o n , c o n c e n t r a t i o n s of Cs i n 1+ sockeye from C u l t u s Lake were not h i g h e r than sockeye f r y from the same l a k e . In Kennedy Lake, the c o n c e n t r a t i o n of Cs was higher i n sockeye smolts compared to sockeye f r y . Whether t h i s suggests t h a t 1+ sockeye from C u l t u s Lake would d i f f e r i n Rb and 1 46 Cs c o n c e n t r a t i o n s compared with migratory smolts caught i n the o u t f l o w i n g r i v e r c o u l d not be f u l l y a s c e r t a i n e d . However, i t may suggest a means of d i f f e r e n t i a t i n g migratory j u v e n i l e sockeye from r e s i d e n t j u v e n i l e sockeye w i t h i n a given year. Furthermore, the e x i s t e n c e of such a d i f f e r e n c e would imply d i f f e r e n t f e e d i n g behaviors or perhaps p h y s i o l o g y . To i n v e s t i g a t e when such a divergence i n Rb and Cs c o n c e n t r a t i o n s would occur i n a p a r t i c u l a r year c l a s s would be of i n t e r e s t . Such an examination may i n d i c a t e when the f a c t o r s governing m i g r a t i o n might come i n t o p l a y . In Lake Aleknagik, Burgner (1962) observed that sockeye f r y were present i n the shallow beach area of the lake u n t i l mid- J u l y , when they moved o f f s h o r e i n t o deeper water. Threespine s t i c k l e b a c k f o l l o w e d a s i m i l a r p a t t e r n of o f f s h o r e m i g r a t i o n . Threespine s t i c k l e b a c k and j u v e n i l e sockeye captured onshore and o f f s h o r e would not be expected to c o n t r a s t markedly i n Rb and Cs for w i t h i n s p e c i e s comparisons because.of t h e i r s i m i l a r recent h i s t o r i e s . Rubidium and Cs c o n c e n t r a t i o n s were not s i g n i f i c a n t l y d i f f e r e n t i n mid-July 1983 f o r w i t h i n s p e c i e s c o n t r a s t s between capture s i t e s i n Lake Aleknagik. Rubidium c o n c e n t r a t i o n s were not s i g n i f i c a n t l y d i f f e r e n t between s p e c i e s c o n t r a s t s but t h r e e s p i n e s t i c k l e b a c k from both onshore and o f f s h o r e capture s i t e s were s i g n i f i c a n t l y d i f f e r e n t i n Cs c o n c e n t r a t i o n s from j u v e n i l e sockeye captured onshore. Rogers(l968) observed that i n the l i t t o r a l zone winged i n s e c t s were the most important s i n g l e d i e t a r y item of j u v e n i l e sockeye. Threespine s t i c k l e b a c k i n the l i t t o r a l zone ate 1 47 s i m i l a r items to j u v e n i l e sockeye but t h r e e s p i n e s t i c k l e b a c k eggs and p l a n t m a t e r i a l were i n c l u d e d i n the d i e t . In Chapter 4 i t was concluded that t h r e e s p i n e s t i c k l e b a c k eggs d i d not c o n s t i t u t e a sink f o r cesium. Whether p l a n t m a t e r i a l would c o n s t i t u t e a r i c h source of Cs remains unknown. In the l i m n e t i c zone of Lake Aleknagik Rogers (1968) observed t h a t both s p e c i e s fed p r i m a r i l y on zooplankton, i n s e c t s were r e l a t i v e l y unimportant. No s i g n i f i c a n t d i f f e r e n c e i n Cs c o n c e n t r a t i o n s was found between these s p e c i e s i n the l i m n e t i c zone of the l a k e . Although t h i s was not the p a t t e r n observed i n Kennedy Lake f o r t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye caught o f f s h o r e on May 25th, i t was the p a t t e r n observed i n Kennedy Lake i n June and J u l y (Chapter 4). Comparison of l a k e s i n d i f f e r e n t c l i m a t i c zones would appear to r e q u i r e more e x t e n s i v e sampling i n both l a k e s throughout the seasons of comparison. A comparison of Kennedy, C u l t u s , Great C e n t r a l , and Lake Aleknagik as a group r e v e a l e d a s i g n i f i c a n t d i f f e r e n c e i n Cs c o n c e n t r a t i o n s between j u v e n i l e sockeye captured o f f s h o r e and t h r e e s p i n e s t i c k l e b a c k captured onshore. In Chapter 3, use of onshore h a b i t a t s was a s s o c i a t e d w i t h higher Cs c o n c e n t r a t i o n s . A c c o r d i n g to the ranking of d i f f e r e n c e s i n Cs c o n c e n t r a t i o n s between t h r e e s p i n e s t i c k l e b a c k c a p t u r e d onshore and j u v e n i l e sockeye ca p t u r e d o f f s h o r e , Great C e n t r a l Lake and Lake Aleknagik suggested the g r e a t e s t o v e r l a p i n d i e t . Rogers (1968) i n d i c a t e d t h a t i n Lake Aleknagik these s p e c i e s do o v e r l a p to a c o n s i d e r a b l e extent but there are d i f f e r e n c e s . Manzer (1976) 1 48 concluded that although t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye i n Great C e n t r a l Lake d i d not o v e r l a p to a great extent i n h a b i t a t they d i d so i n d i e t . Although these o b s e r v a t i o n s - do not d i s a g r e e with observed rankings by Cs c o n c e n t r a t i o n s , t h e i r use as v a l i d a t i o n of the l a t t e r remains l i m i t e d u n t i l s i m i l a r d i e t a r y i n f o r m a t i o n e x i s t s f o r a l l four l a k e s . Why Rb c o n c e n t r a t i o n s f a i l e d to r e v e a l d i f f e r e n c e s between t h r e e s p i n e s t i c k l e b a c k captured onshore and j u v e n i l e sockeye c a p t u r e d o f f s h o r e was not known. However, t h r e e s p i n e s t i c k l e b a c k h e l d over d i f f e r e n t types of s u b s t r a t e s i n Chapter 3, suggested t h a t f e e d i n g over s u b s t r a t e s not a s s o c i a t e d with mud would r e s u l t i n Rb c o n c e n t r a t i o n s s t a t i s t i c a l l y i n d i s t i n g u i s h a b l e from f i s h t h a t had f ed o f f s h o r e . C o n c e n t r a t i o n s of Rb and Cs d i f f e r e d i n the four l a k e s examined. Low c o n c e n t r a t i o n s of Cs i n f i s h have been a s s o c i a t e d with t u r b i d l a k e s (Kolehmainen and Nelson 1969). Many authors have a l s o noted a c o r r e l a t i o n between potassium content i n freshwater and Cs-137 content i n f i s h (Preston et a l . 1967, Kolehmainen et a l . 1968a, Kolehmainen and Nelson 1969, and Solyus 1970). However, the c o n c e n t r a t i o n of Cs-137 i n f i s h appears to be independent of potassium c o n c e n t r a t i o n s when the l a t t e r l i e i n the range of 2 to 30 ppb (McDonald et a l . 1971). There appear to be no s t u d i e s i n the l i t e r a t u r e t h a t have measured Rb i n f i s h from d i f f e r e n t l a k e s . The p r e c i s e reasons f o r d i f f e r e n t Rb and Cs c o n c e n t r a t i o n s among Kennedy, C u l t u s , Great C e n t r a l , and Lake Aleknagik remains unknown. In c o n c l u s i o n , comparison of Rb and Cs c o n c e n t r a t i o n s i n 149 f i s h among lak e s i s imprecise because of an i n a b i l i t y to f i n d a r e f e r e n c e a g a i n s t which a l l r e s u l t s can be weighed. 150 M a t e r i a l s and methods S e c t i o n 3: C o t t i d s , peamouth chub, r e d s i d e s h i n e r s and squawfish C u l t u s Lake was sampled by beach seine on May 15th and June 16th, 1985 f o r Cottus asper, M y l o c h e i l u s c a u r i n u s , R i c h a r d s o n i u s b a l t e a t u s , and P t y c h o c h e i l u s oregonensis. S i m i l a r l y , M y l o c h e i l u s c a u r i n u s , and Cottus asper were c o l l e c t e d from Kennedy Lake on August 11th, 1985. A n a l y s i s f o r Rb and Cs c o n c e n t r a t i o n s was performed on groups of 8 f i s h . 151 R e s u l t s The c o n c e n t r a t i o n s of Rb and Cs i n f i s h t i s s u e s were h i g h l y v a r i a b l e w i t h i n and among c e r t a i n s p e c i e s ( F i g u r e 2 9 - 3 1 ) . Median and q u a r t i l e p l o t s i n d i c a t e d t h a t d i s t r i b u t i o n s were i n most c a s e s skewed towards h i g h e r c o n c e n t r a t i o n s w i t h the e x c e p t i o n of peamouth chub from Kennedy Lake ( F i g u r e 3 2 ) . Kennedy Lake peamouth chub had the g r e a t e s t range of Rb c o n c e n t r a t i o n s compared w i t h a l l o t h e r groups of f i s h but the same p a t t e r n was not m i r r o r e d i n Cs c o n c e n t r a t i o n s ( F i g u r e 3 2 ) . C u l t u s Lake c o t t i d s and s h i n e r s a l s o e x h i b i t e d l a r g e v a r i a t i o n s i n Cs c o n c e n t r a t i o n s but t h e same p a t t e r n was not m i r r o r e d i n Rb c o n c e n t r a t i o n s . C o n c e n t r a t i o n s of Rb and Cs were s i g n i f i c a n t l y d i f f e r e n t among f i s h g r o u p s ( F i g u r e 32, RW; Rb: H=36.53, C s : H=15.57, P < 0 . 0 5 , d f = 5 ) , w i t h Kennedy Lake peamouth and c o t t i d s s i g n i f i c a n t l y h i g h e r i n Rb c o n c e n t r a t i o n s than C u l t u s Lake peamouth, c o t t i d s , and s q u a w f i s h and C u l t u s Lake s q u a w f i s h s i g n i f i c a n t l y h i g h e r i n Cs c o n c e n t r a t i o n s than C u l t u s Lake peamouth and s h i n e r s (NPMC, T a b l e 16 and 17). C o m p a r i s o n of Rb and Cs c o n c e n t r a t i o n s among f i s h groups r e s u l t e d i n two d i f f e r e n t s e t s of s i g n i f i c a n t c o n t r a s t s d e p e n d i n g on w h i c h t r a c e m e t a l was s e l e c t e d . 1 52 F i g u r e 29. Rubidium c o n c e n t r a t i o n s p l o t t e d a g a i n s t dry weight of f i s h f o r peamouth chub and c o t t i d s from Kennedy(symbol +) and C u l t u s Lake(symbol o ) , and squawfish and s h i n e r s from C u l t u s Lake. Sample s i z e i s 8. 10000 8000 6000 4000 2000 p e a m o u t h c o t t i d n CL Q. O.Q 2.0 4.0 6.0 0.0 1.0 2.0 3.0 0C 10000 8000 6000 4000 2000 s q u a w f i s h s h i n e r s 0.0 3.0 6.0 9.0 0.4 0.8 1.2 1.8 dry wt (g) 1 54 F i g u r e 30. Cesium c o n c e n t r a t i o n s p l o t t e d a g a i n s t dry weight of f i s h f o r peamouth chub and c o t t i d s from Kennedy(symbol +) and C u l t u s Lake(symbol o ) , and squawfish and s h i n e r s from C u l t u s Lake. Sample s i z e i s 8. p e a m o u t h c o t t l d n Q. cn u 1200 1000 8 0 0 BOO 4 0 0 2 0 0 1200 1000 BOO 600 400 200 0.0 2.0 4.0 6.0 s q u a w f i s h 0.0 1.0 2.0 3.0 s h i n e r s 0.0 3.0 6.0 9.0 0.4 O.B 1.2 1.6 dry wt (g) 1 5 6 F i g u r e 31. Rubidium and Cs c o n c e n t r a t i o n s p l o t t e d a g a i n s t dry weight of f i s h f o r peamouth chub from C u l t u s Lake. S c a l e has been expanded to show absence of a r e l a t i o n s h i p with dry weight. Sample s i z e i s 8. 4000 3000 2000 1000 0.0 0.02 0.04 0.06 dry wt (g) 1 58 F i g u r e 32. Q u a r t i l e and median p l o t s f o r Rb and Cs c o n c e n t r a t i o n s f o r peamouth chub ( l ) , c o t t i d s ( 2 ) from Kennedy and C u l t u s Lake, and squawfish (3) and s h i n e r s (4) from C u l t u s Lake. Sample s i z e i s 8. A long h o r i z o n t a l l i n e i s drawn through the median of the d a t a . The upper and lower extremes of the t h i c k v e r t i c a l l i n e r e present the upper and lower q u a r t i l e s . The upper end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the l a r g e s t o b s e r v a t i o n that i s l e s s than or equal to the upper q u a r t i l e p l u s 1.5 x the i n t e r q u a r t i l e range. The lower end of the t h i n v e r t i c a l l i n e i s d e f i n e d to be the . s m a l l e s t o b s e r v a t i o n that i s g r e a t e r than or equal to the lower q u a r t i l e minus 1.5 x the i n t e r q u a r t i l e range. A l l v alues o u t s i d e the upper and lower extremes of the t h i n v e r t i c a l l i n e are p l o t t e d as "*". 159 C u l t u s K e n n e d y o. a. JQ ac 8 0 0 0 6 0 0 0 4 0 0 0 2 0 0 0 0 C u l t u s K e n n e d y JQ a. a. cn CJ g r o u p i n g s 160 Table 16. M u l t i p l e comparisons 1 f o r Rb c o n c e n t r a t i o n s i n f i s h c a p t u r e d i n Kennedy and C u l t u s Lake. Numbers i n margins are median v a l u e s . C C C pea c o t t squa 1 2 3 1500 1450 1350 c pea 1 500 1 C c o t t 1450 2 C squa 1 350 3 C s h i 1900 4 K pea 6300 5 * 5.69 * • 5.82 * 5.98 K c o t t 3000 6 * 4.93 * 5.13 * 5.29 1 NPMC * s i g n i f i c a n t l y d i f f e r e n t q v a l u e s , q c r i t i c a l =4.03, a = 0.05, d f * »,6 1-4 C u l t u s l a k e , peamouth, c o t t i d , squawfish, s h i n e r s 5-6 Kennedy l a k e , peamouth, c o t t i d C K K s h i pea c o t t 4 5 6 1400 6300 3000 161 Table 17. M u l t i p l e comparisons 1 f o r Cs c o n c e n t r a t i o n s i n f i s h c a p t u r e d i n Kennedy and C u l t u s Lake. Numbers i n margins are median v a l u e s . c c c c K K pea c o t t squa s h i pea c o t t 1 2 3 4 5 6 430 500 530 410 440 470 c pea 430 1 C c o t t 500 2 C squa * 530 4.58 3 C s h i * 410 4.81 4 K pea 440 5 K c o t t 470 6 1 NPMC * s i g n i f i c a n t l y d i f f e r e n t q v a l u e s , q c r i t i c a l = 4.03, a = 0.05, df= »,6 1-4 C u l t u s l a k e , peamouth, c o t t i d , squawfish, s h i n e r s 5-6 Kennedy l a k e , peamouth, c o t t i d 1 62 D i s c u s s i o n In comparisons of peamouth chub and c o t t i d s , c o n c e n t r a t i o n s of Rb and Cs were higher f o r both s p e c i e s i n Kennedy Lake compared to C u l t u s Lake. T h i s o b s e r v a t i o n concurred with the lower ranking f o r Cs c o n c e n t r a t i o n s i n C u l t u s Lake f o r j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k compared to Kennedy Lake. The range of v a r i a t i o n i n Rb c o n c e n t r a t i o n s i n peamouth chub i n Kennedy Lake would appear to r e f l e c t i n g e s t i o n of d i f f e r e n t types of prey, as yet unknown. Fleishman (1973) observed g r e a t e r s c a t t e r f o r s p e c i f i c a c t i v i t i e s of Cs-137 i n f i s h with broad food s p e c t r a s . Fleishman (1973) r e p o r t e d a c o e f f i c i e n t of v a r i a t i o n of 49 to 45% f o r lake and l a k e - r i v e r char as opposed to only 15-16% f o r j u v e n i l e sockeye. Nelson and Whicker (1969) has a l s o r e p o r t e d l a r g e v a r i a t i o n s of Cs-137 i n f i s h with standard e r r o r s of the mean ranging from 2 to 48% between i n d i v i d u a l s of the same s p e c i e s from the same l a k e . Large v a r i a t i o n s i n stomach contents w i t h i n s i m i l a r i n d i v i d u a l s of the same s p e c i e s has been r e p o r t e d by s e v e r a l authors ( F o e r s t e r 1968, Eggers 1978, and E l i n o r and Hadley 1979). The v a r i a b i l i t y i n Rb c o n c e n t r a t i o n s observed i n peamouth chub may be due to a h i g h l y d i v e r s e d i e t . The higher c o n c e n t r a t i o n s of Cs i n the p i s c i v o r o u s squawfish compared to the other mainly i n s e c t i v o r o u s s p e c i e s i n Cu l t u s Lake was i n g e n e r a l agreement with the o b s e r v a t i o n of an in c r e a s e i n a c t i v i t y l e v e l of Cs-137 i n p i s c i v o r o u s f i s h exceeding 2 to 3 times that of s p e c i e s e a t i n g bottom animals and plankton (Kolehmainen et a l . 1967). Squawfish sampled from 163 C u l t u s Lake ranged from 10.0 to 15.8 cm. S c o t t and Crossman (1973) r e p o r t e d t h a t squawfish over 10.0 cm are mainly p i s c i v o r o u s . Stomach contents of squawfish sampled from Cultus. Lake c o n t a i n e d i n s e c t s , but no f i s h were found. T h i s may e x p l a i n , that a l t h o u g h Cs c o n c e n t r a t i o n s were higher i n squawfish, they d i d not exceed the Cs c o n c e n t r a t i o n s of i n s e c t i v o r o u s f i s h of C u l t u s Lake by a f a c t o r as great as 2 to 3 times the c o n c e n t r a t i o n s i n the l a t t e r . 1 64 General d i s c u s s i o n Many approaches have been used to i n v e s t i g a t e f e e d i n g h a b i t s among f i s h . . Present " i n s i t u " methods u s u a l l y i n v o l v e a n a l y s i s of stomach contents obtained from a sampling program s t r u c t u r e d i n accordances with time of year, day and area. D i r e c t o b s e r v a t i o n s may accompany these r e s u l t s . V a r i o u s types of e n c l o s u r e s have a l s o been employed to e l i m i n a t e confounding f a c t o r s and p r o v i d e an arena i n which the number of p o t e n t i a l c o mpetitors and food resources can be assessed. Use of Rb and Cs to examine fee d i n g behavior of t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye demanded the p r e r e q u i s i t e of e s t a b l i s h i n g a l i n k between Rb and Cs i n d i e t and subsequent c o n c e n t r a t i o n s i n f i s h . T h i s study suggests that the c l a s s i f i c a t i o n by K a n e v s k i i and Fleishman (1972) of f i s h i n t o planktophages and benthophages on the b a s i s of Rb and Cs i n f i s h , i s an o v e r s i m p l i f i c a t i o n . Such broad c a t e g o r i e s were not capable of r e s o l v i n g d i f f e r e n c e s i n Cs c o n c e n t r a t i o n s between j u v e n i l e sockeye and t h r e e s p i n e s t i c k l e b a c k c aptured o f f s h o r e i n Kennedy Lake i n May, as both s p e c i e s were a p p a r e n t l y f e e d i n g on zooplankton. Cesium uptake experiments i n Chapter 2 were an i n i t i a l attempt to demonstrate that such d i f f e r e n c e s c o u l d be accounted f o r by d i f f e r e n c e s i n d i e t between f i s h and not d i f f e r e n c e s i n uptake and e x c r e t i o n r a t e s . However, a cesium e n r i c h e d zooplankton d i e t d i d not r e s u l t i n d i f f e r e n t body burdens of Cs i n j u v e n i l e 165 coho and t h r e e s p i n e s t i c k l e b a c k , though v a r i a t i o n i n Cs c o n c e n t r a t i o n s i n stomach co n t e n t s from the same f i s h suggested s e l e c t i o n of d i f f e r e n t prey items. W i l l i a m s and Swanson (1958) r e p o r t e d c o n s i d e r a b l e v a r i a b i l i t y i n Cs-137 i n a number of d i f f e r e n t s p e c i e s of a l g a e , though t h i s aspect does not appear to have been addressed f o r zooplankton. Pendleton (1962) has proposed an a c t i v e t r a n s p o r t model f o r e n t r y of Cs i n t o c e l l s . In t h i s study, a c a r r i e r f o r Cs may have been s a t u r a t e d by e x c e e d i n g l y h i g h l e v e l s of Cs i n e n r i c h e d zooplankton, hence body burdens of Cs i n f i s h were not s i g n i f i c a n t l y d i f f e r e n t . Much of the u n c e r t a i n t y i n the use of Rb and Cs to d e t e c t d i f f e r e n c e s i n d i e t appears to be r e l a t e d to a l a c k of i n f o r m a t i o n r e g a r d i n g c o n c e n t r a t i o n s among d i f f e r e n t s p e c i e s of prey consumed. Examination of uptake r a t e s of Rb and Cs i n f i s h s hould not only i n c l u d e d i f f e r e n t s p e c i e s of prey but d i f f e r e n t l e v e l s of Rb and Cs enrichment i n the l a t t e r . Demonstration of h a b i t a t u t i l i z a t i o n p a t t e r n s by t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e sockeye was a major f a c e t of t h i s study. T r a n s f e r experiments conducted i n Chapter 3 i n d i c a t e d that the a b i l i t y of Rb and Cs to d e t e c t d i f f e r e n t i a l use of onshore and o f f s h o r e h a b i t a t s by t h r e e s p i n e s t i c k l e b a c k was dependent on the type of s u b s t r a t e over which f i s h had f e d . A lack of a s i g n i f i c a n t d i f f e r e n c e between f i s h c a ptured i n the l i t t o r a l zone compared to the l i m n e t i c zone of a lake c o u l d not be regarded as c o n c l u s i v e evidence that f i s h had s i m i l a r d i e t s . Cesium c o n c e n t r a t i o n s were not s i g n i f i c a n t l y d i f f e r e n t i n t h r e e s p i n e s t i c k l e b a c k h e l d over sand, cobble, sand(mud), and 1 66 gravel(mud) s u b s t r a t e s . In c o n t r a s t Gustafson (1969) noted a c o r r e l a t i o n between Cs-137 content of f i s h and content of Cs-137 near the s i t e of c a p t u r e . L e v e l s of Cs-137 i n prey were not. determined, hence t h e i r c o r r e l a t i o n with sediments was not known. Rabe and Stephens (1977) were a b l e to d e t e c t w i t h i n a s i n g l e s p e c i e s of f i s h , l e v e l s of Cs-137 unique to the s t a t i o n sampled. In the c u r r e n t study, Cs c o n c e n t r a t i o n s were not s i g n i f i c a n t l y d i f f e r e n t among f i s h h e l d over d i f f e r e n t s u b s t r a t e types. Rubidium c o n c e n t r a t i o n s were however, s i g n i f i c a n t l y h igher i n t h r e e s p i n e s t i c k l e b a c k h e l d over sand and cobble compared to gravel(mud) and sand(mud) s u b s t r a t e s . The i n v e s t i g a t i o n of s t i c k l e b a c k s i n Enos Lake suggested t h a t Rb and Cs c o n c e n t r a t i o n s may be used to i d e n t i f y the types of s u b s t r a t e s over which f i s h were f e e d i n g . Based on Rb and Cs c o n c e n t r a t i o n s observed i n t h r e e s p i n e s t i c k l e b a c k captured o f f s h o r e and h e l d over v a r i o u s s u b s t r a t e s i n Kennedy Lake (Chapter 3), higher c o n c e n t r a t i o n s of Rb i n benthic male s t i c k l e b a c k compared to benthic females appeared to be the r e s u l t of f e e d i n g over mud a s s o c i a t e d s u b s t r a t e s by the former. However, i t i s not known i f Rb and Cs c o n c e n t r a t i o n s i n t h r e e s p i n e s t i c k l e b a c k having fed over d i f f e r e n t s u b s t r a t e s i n Kennedy Lake i n d i c a t e s a g e n e r a l p a t t e r n , e q u a l l y a p p l i c a b l e to other l a k e s . S t u d i e s by Gustafson (1969) f a i l e d to d e t e c t a d i f f e r e n c e i n Cs-137 c o n c e n t r a t i o n s i n bottom sediments of Red Lake, Minnesota. In a small l a k e , G a l l e g o s (1970) found no d i f f e r e n c e i n Cs-137 i n sediment as a f u n c t i o n of depth or d i s t a n c e from the s h o r e l i n e . C o n c e n t r a t i o n s of Cs were not 1 6 7 examined i n d i f f e r e n t sediments i n Kennedy Lake. As a c o u n t e r p a r t to examining Rb and Cs c o n c e n t r a t i o n s i n d i f f e r e n t s p e c i e s of zooplankton i n the l i m n e t i c zone of Kennedy Lake, Rb and Cs c o n c e n t r a t i o n s should be examined i n prey s p e c i e s from d i f f e r e n t p a r t s of the l i t t o r a l zone as w e l l . Seasonal changes i n the use of onshore and o f f s h o r e h a b i t a t s i n Kennedy Lake by t h r e e s p i n e s t i c k l e b a c k were not indexed by subsequent changes i n body burdens of Rb and Cs i n f i s h . Movement of t h r e e s p i n e s t i c k l e b a c k onshore to breed i n Kennedy lake d i d not r e s u l t i n higher c o n c e n t r a t i o n s of Rb and Cs compared with f i s h c a p t u r e d o f f s h o r e . Feeding over gravel(mud) s u b s t r a t e s c o u l d account f o r t h i s o b s e r v a t i o n but t h r e e s p i n e s t i c k l e b a c k were ca p t u r e d i n Kennedy lake over numerous types of s u b s t r a t e s . C o n c e n t r a t i o n s of Rb and Cs i n t h r e e s p i n e s t i c k l e b a c k c a p t u r e d onshore may represent an i n t e g r a t i o n of food items over v a r i o u s types of s u b s t r a t e s but t h i s can o n l y lend c o n f u s i o n i n the d e t e c t i o n of d i f f e r e n c e s i n u t i l i z a t i o n of onshore and o f f s h o r e h a b i t a t s . A comparison between t h r e e s p i n e s t i c k l e b a c k captured onshore and j u v e n i l e sockeye c a p t u r e d o f f s h o r e from Kennedy, Great C e n t r a l , C u l t u s , and Lake Aleknagik r e v e a l e d a s i g n i f i c a n t d i f f e r e n c e i n Cs c o n c e n t r a t i o n s . However, i t remains u n c e r t a i n as to whether t h i s d i f f e r e n c e would e x i s t between s p e c i e s f o r samples taken l a t t e r i n the season, as no d i f f e r e n c e i n Rb and Cs c o n c e n t r a t i o n s between these s p e c i e s was found i n Kennedy Lake i n J u l y . Present evidence would suggest that d i f f e r e n c e s i n Cs c o n c e n t r a t i o n s between t h r e e s p i n e s t i c k l e b a c k and j u v e n i l e 168 sockeye i n these l a k e s c o u l d be a t t r i b u t e d to d i f f e r e n c e s i n d i e t a s s o c i a t e d with occupation of onshore or o f f s h o r e h a b i t a t s . However, i n l i g h t of sources of v a r i a b i l i t y i n body burdens of Cs i n f i s h c i t e d i n the l i t e r a t u r e and demonstrated i n t h i s study, d i f f e r e n c e s i n Cs c o n c e n t r a t i o n s i n f i s h cannot be regarded as a q u a n t i t a t i v e measure of o v e r l a p i n h a b i t a t or h a b i t a t u t i l i z a t i o n p a t t e r n s . H e r e i n l i e s the major weakness of a s s e s s i n g o v e r l a p i n d i e t i n f i s h by measuring body burdens of Rb and Cs i n f i s h . In c o n c l u s i o n , the present understanding of Rb and Cs dynamics i n f i s h as r e l a t e d to d i e t appears i n s u f f i c i e n t f o r wide and g e n e r a l a p p l i c a t i o n . I n v e s t i g a t i o n of uptake and e x c r e t i o n p a t t e r n s i n c o n j u n c t i o n with a s s e s s i n g a v a i l a b i l i t y of prey items r e f l e c t i n g d i f f e r e n t Rb and Cs c o n c e n t r a t i o n s would at present make t h i s method u n a t t r a c t i v e to f i s h e r i e s managers. The most promising prospect f o r i t s use would appear to be s m a l l l a k e s with few s p e c i e s of f i s h . Other a p p l i c a t i o n s may i n c l u d e i t s use as a b i o l o g i c a l marker, i n d i c a t i n g p o s s i b l e changes i n behavior or p h y s i o l o g y . More r a p i d techniques f o r measuring t r a c e elements,^ e n a b l i n g examination of a whole spectrum of elements at once; at reasonable c o s t , may provide a more powerful t o o l i n the f u t u r e f o r i n v e s t i g a t i n g d i e t and h a b i t a t s e l e c t i o n by f i s h . 169 REFERENCES AEC, Radioecology of some n a t u r a l organisms and systems i n Colorado. F a c t o r s a f f e c t i n g Cs-137 accumulation i n t r o u t . Department of r a d i o l o g y and r a d i a t i o n b i o l o g y . Colorado S t a t e U n i v e r s i t y . F o r t C o l l i n s , Colorado. 6th annual p r o g r e s s report on atomic energy. January 1, 1967-December 31, 1967. B a p t i s t , J . P., and T. J . P r i c e . 1962. Accumulation and r e t e n t i o n of cesium-137 by marine f i s h e s . U. S. A. Dept. I n t . F i s h and W i l d l i f e Ser. F i s h . B u l l . 62:177- 187. B a r r a c l o u g h , W. E., and D. Robinson. 1971. The f e r t i l i z a t i o n of Great C e n t r a l Lake I I I . E f f e c t s on j u v e n i l e sockeye salmon. F i s h . B u l l . 70:37-48. Becker, R. A., and J . M. Chambers. 1984. S an i n t e r a c t i v e environment f o r data a n a l y s i s and g r a p h i c s . Wadsworth advanced book program. Belmont, C a l i f o r n i a . Bentzen, P., and J . D. M c P h a i l . 1984. Ecology and e v o l u t i o n of sympatric s t i c k l e b a c k s ( G a s t e r o s t e u s ) : s p e c i a l i z a t i o n f o r a l t e r n a t e t r o p h i c n i c h e s i n the Enos Lake s p e c i e s p a i r . Can. J . Z o o l . 62: 2280-2286. Bentzen, P, Ridgeway, M.S., and J . D. M c P h a i l . 1984. Ecology and e v o l u t i o n of sympatric s t i c k l e b a c k s ( G a s t e r o s t e u s ) : s p a t i a l s e g r e g a t i o n and seasonal h a b i t a t s h i f t s i n the Enos Lake p a i r Can. J . Z o o l . 62:2436-2439. Bryan, J.E., and P.A. L a r k i n . 1972. Food s p e c i a l i z a t i o n by i n d i v i d u a l t r o u t . J . F i s h . Res. Bd. Canada 29:1615- 1624. Burgner, R. L. 1959. Study of p o p u l a t i o n d e n s i t y and c o m p e t i t i o n between p o p u l a t i o n s of young red salmon and s t i c k l e b a c k s . C o n t r i b u t i o n No. 70, C o l l e g e of F i s h e r i e s , U n i v e r s i t y of Washington. Burgner, R. L. 1962. Sampling red salmon f r y by lake t r a p i n the Wood River Lakes A l a s k a . I_n T. S. Y. Koo [ed.] S t u d i e s of A l a s k a red salmon. U n i v e r s i t y of Washington P r e s s , S e a t t l e , 1962. Clady, M.D., and G. W. Luker. 1982. Competition between s p o t t e d and largemouth bass i n v a r i a b l e pond ecosystems. Trans. Amer. F i s h . Soc. 111:665-674. Copeland, R. A., J . C. Ayers, . and the s t a f f of the environmental r e s e a r c h group, Inc. 1972. Trace element d i s t r i b u t i o n i n water, sediment, phytoplankton, zooplankton, and benthos of Lake Michigan: a b a s e l i n e study w i t h c a l c u l a t i o n s of c o n c e n t r a t i o n f a c t o r s and b u i l d u p of 170 r a d i o i s o t o p e s i n the food web. Environmental Research group Inc., Ann Arbor, Michigan, S p e c i a l Report. C o n n e l l , J . H. 1983. On the prevalence and r e l a t i v e importance of i n t e r s p e c i f i c c o m p e t i t i o n : evidence from f i e l d experiments. Am. Nat. 122:661-696. Copeland, R. A., R. H. Beethe, and W. W. P r a t e r . 1973. Trace elements d i s t r i b u t i o n s i n Lake Michigan f i s h : a b a s e l i n e study with c a l c u l a t i o n s of c o n c e n t r a t i o n f a c t o r s and e q u i l i b r i u m r a d i o i s o t o p e d i s t r i b u t i o n s . Environmental r e s e a r c h group Inc., Ann Abor, Michigan, S p e c i a l Report, March 1973. Coughtrey, P. J . , and M. C. Thorne. 1983. R a d i o n u c l i d e d i s t r i b u t i o n and t r a n s p o r t i n t e r r e s t r i a l and a q u a t i c ecosystems. A c r i t i c a l review of data. A. A. Balkema, Rotterdam. Cushing, C. E. ( J r . ) . 1979. Trace elements i n a Columbia r i v e r food web. Northwest Science 52(2):118-125. Dav i s , J . J . 1963. Cesium and i t s r e l a t i o n s h i p s to potassium i n ecology. p. 539-556. I_n Radioecology. Proceedings of the f i r s t n a t i o n a l symposium on r a d i o e c o l o g y h e l d a t Colorado S t a t e U n i v e r s i t y , F o r t C o l l i n s , Colorado, September 10-15, 1961. De B e r n a r d i , R. 1981. B i o t i c i n t e r a c t i o n s i n freshwater and e f f e c t s on community s t r u c t u r e . B u l l . Z o o l . 48:353-371. E b e r h a r t , L. L. 1976. Sampling f o r r a d i o n u c l i d e s and other t r a c e elements. p. 200-208. I_n C. E. Cushing [ed.] Radioecology and energy r e s o u r c e s . Proceedings of the f o u r t h n a t i o n a l symposium i n r a d i o e c o l o g y May 12-14, 1975, Oregon S t a t e U n i v e r s i t y , C o r v a l l i s , Oregon. Eggers, D. M. 1978. L i m n e t i c f e e d i n g behavior of j u v e n i l e sockeye salmon i n Lake Washington and predator avoidance. Limnol. Oceanogr. 23(6):1114-1125. Eggers, D. M. 1982. P l a n k t i v o r e p r e f erence by prey s i z e . Ecology 63(2):381~390. E l i n o r , L. G., W. F. Hadley. 1979. Food and h a b i t a t p a r t i t i o n i n g between rock bass (Ambloplites r u p e s t r i s ) and smallmouth bass ( M i c r o p t e r u s dolomieui). young of the year. Trans. Am. F i s h . Soc. 188:253-261. Fleishman, D. G. 1973. Accumulation of a r t i f i c i a l r a d i o n u c l i d e s i n f i s h . p. 347-370. In K l e c h k o v s k i i , G. G. P o l i k a r p o v , and R. M. Aleksakhin - T e d s.] Radioecology. John Wiley and Sons. T r a n s l a t e d from Russian. 171 F o e r s t e r , R. E. 1929. An i n v e s t i g a t i o n of the l i f e h i s t o r y and propagation of the sockeye salmon (Oncorhynchus nerka) at C u l t u s Lake, B r i t i s h Columbia. No. 3. The downstream m i g r a t i o n of the young i n 1926 and 1927. C o n t r i b . Canadian B i o l . F i s h . 5(1):55-82. F o e r s t e r , R. E. 1968. The sockeye salmon Oncorhynchus nerka. B u l l . F i s h . Res. Board Can. 162:422p.. G a l l e g o s , A. F. 1970. Radiocesium k i n e t i c s i n the components of a montane lake ecosystem. Colorado Sate U n i v e r s i t y , Ph. D.. Greenbank, J . , and P. R. Nelson. 1959. L i f e h i s t o r y of the t h r e e s p i n e s t i c k l e b a c k G a s t e r o s t e u s a c u l e a t u s Linnaeus i n Karluk Lake and Bare Lake, Kodiak I s l a n d , A l a s k a . U. S. F i s h . W i l d . Serv., F i s h . B u l l . 59:537-559. Grobenski, Z. D., D. Weber, B.. Welz, and J . W o l f f . 1983. Determination of caesium and rubidium by flame and furnace a t o m i c - a b s o r p t i o n spectrometry. A n a l y s t 108:925-932. Gustafson, P. F. 1967. Comments on r a d i o n u c l i d e s i n a q u a t i c ecosystems. p. 921-924. I_n B. Aberg and F. P. Hungate [eds.] R a d i o e c o l o g i c a l c o n c e n t r a t i o n p r o c e s s e s . Proceedings of an i n t e r n a t i o n a l symposium h e l d i n Stockholm 25-29 A p r i l , 1966. Pergamon Pr e s s , New York, N.Y.. Gustafson, P. F. 1969. Cesium-137 i n freshwater f i s h d u r i n g 1954-1965. p. 249-257. In Nelson, J . D., and Evans F. C. [eds.] Symposium on r a d i o e c o l o g y . Proceedings of the second n a t i o n a l symposium h e l d a t Ann Arbor, Michigan, May 15-17, 1967. Hakonson, T. E., A. F. G a l l e g o s and F. W. Whicker. 1971. Use of cesium-133 and a c t i v a t i o n a n a l y s i s f o r measurement of cesium k i n e t i c s i n a montane l a k e . p. 344-348. Ln D. J . Nelson [ed.] R a d i o n u c l i d e s i n ecosystems. Proceedings of the 3rd n a t i o n a l symposium on r a d i o e c o l o g y . May 10-12, 1971. V o l . 1. Hannerz, L. 1968. The r o l e of f e e d i n g h a b i t s i n the accumulation of f a l l out Cs-137 i n f i s h . Rept. I n s t . of Freshwater Res. Drottningholm 48:112-119. Hartman, W. L., and R. L. Burgner. 1972. Limnology and f i s h ecology of sockeye nursery l a k e s of the world. J . F i s h . Res. Bd. Canada 29:699-715. Hasanen, E., J . K. M i e t t i n e n . 1963. Cesium-137 content of fresh-water f i s h i n F i n l a n d . Nature 200:1018-1019. Hasanen, E., S. E. Kolehmainen, and J . K. M i e t t i n e n . 1967. B i o l o g i c a l h a l f - t i m e of Cs-137 i n three s p e c i e s of f r e s h - 1 72 water f i s h : perch, roach and rainbow t r o u t , p. 921-924. In W. S. Synder et a l . [eds.] R a d i o e c o l o g i c a l c o n c e n t r a t i o n p r o c e s s e s . Proceedings of an i n t e r n a t i o n a l symposium h e l d i n Stockholm 25-29 A p r i l , 1966. Pergamon Pr e s s , V o l . I. H a s l e r , A. D., and G. E. L i k e n s . 1963. B i o l o g i c a l and p h y s i c a l t r a n s p o r t of r a d i o n u c l i d e s i n s t r a t i f i e d l a k e s , p. 463-470. In W. S c h u l t z and A. W. Klement [eds.] Radioecology. Proceedings of the f i r s t i n t e r n a t i o n a l symposium on r a d i o e c o l o g y h e l d at Colorado S t a t e U n i v e r s i t y , F o r t C o l l i n s , Colorado, September 10-15, 1961. Reinhold, New York. Hyatt, K. D. 1979. Feeding s t r a t e g y , p. 71-119. In W. S. Hoar, D. J . R a n d a l l and J . R. B r e t t [eds.] F i s h p h y s i o l o g y . V o l . 8. Academic Press, New York. J e n k i n s , C. E. 1969. R a d i o n u c l i d e d i s t r i b u t i o n i n p a c i f i c salmon. H e a l t h P h y s i c s 17:507-512. Johannes, R. E., and P. A. L a r k i n . 1961. Competition f o r food between r e d s i d e s h i n e r s (Richardsonius b a l t e a t u s ) and rainbow t r o u t (Salmo g a i r d n e r i ) i n two B r i t i s h Columbian Lakes. J . F i s h . Res. Bd. Canada 18:203-220. K a n e v s k i i , Yu. P., and D. G. Fleishman. 1972. I n v e s t i g a t i o n of food c h a i n s i n an i c h t h y o c o e n o s i s of Lake D a l ' n y i (Kamchatka) a c c o r d i n g to the c o n c e n t r a t i o n s of rubidium and cesium i n h y d r o b i o n t s . Academy of Science of the U.S.S.R. S o v i e t J o u r n a l of Ecology (1972) p. 191-193. T r a n s l a t e d from E k o l o g i y a No.3, p. 5-8, May-June 1971. Keast, A. 1977. Mechanisms expanding niche width and m i n i m i z i n g i n t r a s p e c i f i c c o m p e t i t i o n i n two c e n t r a r c h i d f i s h . I_n E v o l u t i o n a r y b i o l o g y V o l . 10:333-395. Plenum Press, New York. Keast, A., and Welsh, L. 1968. D a i l y f e e d i n g p e r i o d i c i t i e s , food uptake r a t e s , and d i e t a r y changes with hour of day i n some lake f i s h e s . J . F i s h . Res. Bd. Can. 25(6): 1133- 1144. Kevern, N. R. 1966. Feeding r a t e of c a r p estimated by a r a d i o i s o t o p i c method. Trans. Amer. F i s h . Soc. 95:363. Kimura, K e n - i c i . 1984. Accumulation and r e t e n t i o n of cesium- 137 by the common goby. B u l l . of Jap. Soc. of S c i . F i s h . King, S. F. 1964. Uptake^ and t r a n s f e r of cesium-137 by Chlamydomonas, Daphnia and b l u e g i l l f i n g e r l i n g s . Ecology 45(4)-852-858. 50(3):481-487. 1 73 Kleinbaum, D. G., and L. L. Kupper. 1978. A p p l i e d r e g r e s s i o n a n a l y s i s and other m u l t i v a r i a b l e methods. Duxbury Press, C a l i f o r n i a . Kolehmainen, S. E. 1972. The balances of Cs-137, s t a b l e cesium and potassium of b l u e g i l l (Lepomis macrochirus) Raf.) and other f i s h i n White Oak Lake. H e a l t h P h y s i c s 23:301-315. Kolehmainen, S. E. 1974. D a i l y f e e d i n g r a t e s of b l u e g i l l (Lepomis macrochirus) determined by a r e f i n e d r a d i o i s o t o p e method. J . F i s h . Res. Board Can. 31:67-74. Kolehmainen, S. E. Hasanen and J . K. M i e t t i n e n . 1966. Cs- 137 l e v e l s i n f i s h of d i f f e r e n t l i m n o l o g i c a l types of l a k e s i n F i n l a n d d u r i n g 1963. H e a l t h P h y s i c s 12:917-922. Kolehmainen, S. E., and D. J . Nelson. 1969. The balances of Cs-137, s t a b l e cesium, and the f e e d i n g r a t e s of b l u e g i l l ( Lepomis macrochirus Raf.) i n White Oak Lake. USAEC Report ORNL-4445, Oak Ridge N a t i o n a l L a b o r a t o r y . Kolehmainen, S. E., E. Hasanen, and J . K. M i e t t i n e n . 1967. Cs-137 i n f i s h , p lankton and p l a n t s i n F i n n i s h Lakes d u r i n g 1964-5. p. 913-919. In A. B. Aberg and F. P. Hungate [eds.] R a d i o e c o l o g i c a l c o n c e n t r a t i o n p r o c e s s e s . Proceedings of an i n t e r n a t i o n a l symposium h e l d i n Stockholm 25-29 A p r i l , 1966. Kolehmainen, S. E., E. Hasanen, and J . K. M i e t t i n e n . 1968a. Cs-137 i n the p l a n t s , plankton and f i s h of the F i n n i s h Lakes and f a c t o r s a f f e c t i n g i t s accumulation. p. 407-415. Proceedings of the f i r s t i n t e r n a t i o n a l congress of r a d i a t i o n p r o t e c t i o n . September 5-10, 1966. Kolehmainen, S. E., H. Romantschuk, S. T a k a t a l o , and J . K. M i e t t i n e n . 1968b. P o l l u t i o n experiments with Cs-137 i n lakes of two l i m n o l o g i c a l l y d i f f e r e n t types, pp. 181-200. In Congress i n t e r n a t i o n a l sur l a r a d i o p r o t e c t i o n du m i l i e u devant l e development des u t i l i z a t i o n s p a c i f i q u e de l ' e n e r g i e n u c l e a i r e , Toulouse, 14-16, mars 1967. S o c i e t e F r a n c h i s e de R a d i o p r o t e c t i o n , P a r i s . Krogius, F. V., and E. M. Krokhin. 1956. Causes of the f l u c t u a t i o n s i n abundance of sockeye salmon i n Kamchatka. Trudy Problemnikh i Tematicheskikh So v e s h c h a n i i Z o o l . I n s t . Akad. Nauk. USSR, No. 6 p. 144-149. [FRB T r a n s l a t i o n No. 197]. Krogius, F. V., E. M. Krokhin, and V. V. Menshutkin. 1969. The p e l a g i c f i s h community i n Lake Dalnee. An experiment i n c y b e r n e t i c m o d e l l i n g . F i s h . Res. Bd. Can. Trans. Ser. No. 1486. 230p.. 174 Krokhin, E. M. 1959. Determination of the d a i l y food r a t i o n s of young sockeye and t h r e e - s p i n e s t i c k l e b a c k by the r e s p i r a t i o n method . F i s h . Res. Bd. Can. Trans. Ser. No. 209. Krokhin, E. M. 1969. E s t i m a t i o n of the biomass and abundance of the t h r e e s p i n e s t i c k l e b a c k G a s t e r o s t e u s a c u l e a t u s i n Lake Dal'neye based on the food consumption of p l a n k t o n - f e e d i n g f i s h e s . J . I c h t h y o l . 10:471-475. L a r k i n , P. A. 1956. I n t e r s p e c i f i c c o m p e t i t i o n and p o p u l a t i o n c o n t r o l i n freshwater f i s h . J . F i s h . Res. Bd. Can. 13(3):327-342. Levinson, A. A. 1974. I n t r o d u c t i o n to e x p l o r a t i o n geochemistry. A p p l i e d Pub. L t d . C a l g a r y . M a i t l a n d , P. S. 1965. The f e e d i n g r e l a t i o n s h i p s of salmon, t r o u t , minnows, stone l o a c h and t h r e e - s p i n e d s t i c k l e b a c k s i n the r i v e r E n d r i c k S c o t l a n d . J . Anim. E c o l . 34:109- 1 33. Manzer, J . I. 1976. D i s t r i b u t i o n , food, and f e e d i n g of the t h r e e s p i n e s t i c k l e b a c k , Gasterosteus a c u l e a t u s , i n Great C e n t r a l Lake, Vancouver I s l a n d , with comments on c o m p e t i t i o n f o r food with j u v e n i l e sockeye salmon, Oncorhynchus nerka. F i s h . B u l l . 74(3):647-668. Markovtsev, V. G. 1973. Feeding and food r e l a t i o n s h i p s of young sockeye and t h r e e - s p i n e s t i c k l e b a c k i n Lake Dalnee. J . F i s h . Res. Can. Trans. Ser. No. 2830 p. 10. Mauro, J . J . 1973. The accumulation of Cs-137 by Fundulus h e t e r o c l i t u s i n the Hudson R i v e r e s t u a r y . New York U n i v e r s i t y , Ph. D.. McDonald, E. W., J . W. Lentsch, M. Eisenbud, G. L. Lauer, and G. P. Howells. 1971. Radiocesium d i s t r i b u t i o n i n water, sediment, and b i o t a i n the Hudson R i v e r e s t u a r y from 1964 through 1970. p. 334-343. In D. J . Nelson [ed.] R a d i o n u c l i d e s i n ecosystems. Proceedings of the 3rd n a t i o n a l symposium on r a d i o e c o l o g y . May 10-12, 1971, V o l . 1 . M c P h a i l , J . D. 1984. Ecology and e v o l u t i o n of sympatric s t i c k l e b a c k s ( G a s t e r o s t e u s ) : morphology and g e n e t i c evidence f o r a s p e c i e s p a i r i n Enos Lake, B r i t i s h Columbia. Can. J . Z o o l . 62: 1402-1408. M i l i n s k i , M., and R. H e l l e r . 1978. I n f l u e n c e of a predator on the optimal f o r a g i n g behavior of s t i c k l e b a c k s G a s t e r o s t e u s a c u l e a t u s . Nature 275(5681):642-644. Minckley, W. L., J . E. Craddock, and L. A. Krumholz. 1963. 175 N a t u r a l r a d i o a c t i v i t y i n the food web of the banded s c u l p i n Cottus c a r o l i n a e ( G i l l ) . p. 229-236. In V. S c h u l t z and A.W. Klement J r . [eds.] Radioecology. Proceedings of the f i r s t n a t i o n a l symposium h e l d at Colorado S t a t e U n i v e r s i t y , F o r t C o l l i n s , Colarado, September 10-15 1961. Reinhold, New York. Nelson, D. J . 1969. Cesium, cesium-137, and potassium c o n c e n t r a t i o n s i n white c r a p p i e and other C l i n c h r i v e r f i s h . p. 240-248. I_n D. J . Nelson and F. E. Evans [eds.] Symposium on r a d i o e c o l o g y . Proceedings of the second n a t i o n a l symposium h e l d at Ann Arbor, Michigan, May 15-17, 1967 . Nelson, W. C , and F. W. Whicker. 1969. Cesium-137 i n some Colarado game f i s h , 1965-66. p. 258-265. I_n J . D. Nelson and F. E. Evans [eds.] Proceedings of the second n a t i o n a l symposium h e l d at Ann Arbor, Michigan, May 15-17, 1967. N i l s s o n , N i l s - A r v i d . 1958. On the food c o m p e t i t i o n between two s p e c i e s of Coregonus i n a North-Swedish l a k e . Rept. I n s t . Freshwater Res. Drottningholm 39:146-161. Northcote, T. G. and P. A. L a r k i n . 1956. I n d i c e s of p r o d u c t i v i t y i n B r i t i s h Columbia Lakes. J . F i s h . Res. Bd. Canada 13(4):515-540. Pendleton, R. C. 1962. Accumulation of cesium-137 through the a q u a t i c food web. U.S.P.H.S. Pub. 999-Wp-25:355-63. Pendleton, R. C , and W. C. Hanson. 1958. A b s o r p t i o n of cesium-137 by components of an a q u a t i c community. Proceedings of the 2nd i n t e r n a t i o n a l conference on p e a c e f u l uses of atomic energy 18:419-422. Poluektov, N. S., and V. T. Mishchenko 1962. The present s t a t e of the a n a l y t i c a l c hemistry of l i t h i u m , rubidium, and cesium, p. 34-48. I_n A. P. Vinogradov and D. I. Ryabchikov [eds.] D e t e c t i o n and a n a l y s i s of r a r e elements. I s r a e l program f o r s c i e n t i f i c T r a n s l a t i o n s , Jerusalem. Preston, A., D. F. J e f f e r i e s , and J . W. R. Dutton. 1967. The c o n c e n t r a t i o n of caesium-137 and strontium-90 i n the f l e s h of brown t r o u t taken from r i v e r s and l a k e s i n the B r i t i s h I s l e s between 1961 and 1966: the v a r i a b l e s determining the c o n c e n t r a t i o n s and t h e i r use i n r a d i o l o g i c a l assessments. Water Research 1:475-496. P r i c e , W. J . 1979. Spectrochemical a n a l y s i s by atomic a b s o r p t i o n . Heyden and Son L t d . P h i l a d e l p h i a , U.S.A.. Puckett, K. J . , and L. M. D i l l 1984. Cost of maintained and bu r s t swimming speed to j u v e n i l e coho salmon (Oncorhynchus 1 76 k i s u t c h ) . Can. J . F i s h . Aquat. S c i . 41:1546-1551. Rabe , F. W., and B. B. Stephens. 1977. Heavy metals i n l a k e s of the Coeur d'alene r i v e r v a l l e y , Idado. Northwest Science 51 (3):183-197. Rankin, D. P., H. J . Ashton, and 0. D. Kennedy. 1979. Crustacean zooplankton abundance and s p e c i e s composition i n s i x e x p e r i m e n t a l f e r t i l i z e d B r i t i s h Columbian l a k e s . F i s h . Mar. Serv. Tech. Rep. 897:27p. R e i c h l e , D. E., P. B. Dunaway, and D. J . Nelson. 1970. Turnover and c o n c e n t r a t i o n of r a d i o n u c l i d e s i n food c h a i n s . Nuclear S a f e t y 11(1)43-55. R i c k e r , W. E. 1937. P h y s i c a l and chemical c h a r a c t e r i s t i c s of C u l t u s Lake, B r i t i s h Columbia. J . B i o l . Bd. Can. 3(4):346-402. Rogers, D. E. 1968. A comparison of the food of sockeye salmon f r y and t h r e e s p i n e s t i c k l e b a c k i n the Wood Ri v e r l a k e s . I_n F u r t h e r s t u d i e s of A l a s k a sockeye salmon. Univ. Washington P u b l . F i s h . N. S. 3:3-43. Romberg, G. P., and W. C. Renfro. 1973. R a d i o a c t i v i t y i n j u v e n i l e Columbia r i v e r salmon: a model to d i s t i n g u i s h d i f f e r e n c e s i n movement and f e e d i n g h a b i t s . Trans. Amer. F i s h . Soc. 1973(2):317-322. Ru t h e r f o r d , D. T., K. D. Hyatt, J . E. R a d z i u l , and G. J . S t e e r . 1986. P h y s i c a l parameters of sockeye salmon (Oncorhynchus nerka) r e a r i n g l a k e s under study by the Enhancement Unit.' Can. MS Rep. F i s h . Aquat. S c i . 1878: 114 p. Ryan, P. M. 1984. Age, growth, and food of t h r e e s p i n e s t i c k l e b a c k s (Gasterosteus a c u l e a t u s ) i n t h r e e lakes of c e n t r a l Newfoundland, Canada. Can. Tech. Rep. F i s h . A q u a t i c . S c i . 1325:IV + I6p.. Ruggles, C. P. 1965. J u v e n i l e sockeye s t u d i e s i n Owikeno Lake, B r i t i s h Columbia. The Canadian F i s h C u l t u r i s t 36:1- 21 . S c o t t , W. B., and E. J . Crossman 1973. Freshwater f i s h e s of Canada. F i s h . Res. Board Ca. B u l l . No. 184 966p.. S p i g a r e l l i , S. A. 1971. E c o l o g i c a l f a c t o r s a f f e c t i n g the accumulation of cesium-137 f a l l o u t by a n a t u r a l p o p u l a t i o n of largemouth bass (Micropterus s a l m o i d e s ) . p. 328-33. In D. J . Nelson [ed.] R a d i o n u c l i d e s i n ecosystems. Proceedings of the 3rd n a t i o n a l symposium on r a d i o e c o l o g y . May 10-12, 1971. V o l . 1 . 1 77 Solyus, A. A., D. G. Fleishman, and V. G. Leont'ev. 1970. Accumulation of cesium-137 by f i s h of freshwater l a k e s . Vopr. I k h t i o l . J_0 No. 6 (65) : 1 091 -1 097 . Stephens, K., and J . G. Stockner. 1983. The lake enrichment program: methods f o r the f e r t i l i z a t i o n of l a k e s i n B r i t i s h Columbia 1970 t o l 9 8 2 . Can. Tech. Rep. F i s h . Aquat. S c i . 1 1 9 2 : i i i + 51p.. Stockner, J . G. and K. Phytoplankton s u c c e s s i o n Lake, B r i t i s h Columbia. 32:2413-2427. R. S. S h o r t r e e d . 1975. and primary p r o d u c t i o n i n Babine J . F i s h . Res. Board Can. Stockner, J . G. and K. D. Hyatt. 1984. Lake f e r t i l i z a t i o n : S t a t e of the a r t a f t e r 7 years of a p p l i c a t i o n . Can. Tech. Rep. F i s h . Aquat. S c i . 1324:33 p. Stockner, J . G., K. S. Shortreed, and K. Stephens. 1980. The B r i t i s h Columbia lake f e r t i l i z a t i o n program: l i m n o l o g i c a l r e s u l t s from the f i r s t 2 y ears of n u t r i e n t enrichment. F i s h , and Mar. Serv. Tech. Rep. 924:9lp.. Svardson, G. 1949. Competition between t r o u t and char (Salmo t r u t t a ) and (S. a l p i n u s ) . Rept. I n s t . Freshw. Res. Drottningholm 29:108-111. Tanka, G., A. Tomikawa, and H. Kawamura. 1977. Determination of rubidium i n b i o l o g i c a l m a t e r i a l s u s i n g atomic a b s o r p t i o n s p e c t r o s c o p y . B u l l . Chem. Soc. Japan 50(9):2310-2316. T i l l e r , I. V. 1974. Age and growth r a t e of t h r e e - s p i n e s t i c k l e b a c k (Gasterosteus a c u l e a t u s ) i n Lake Dal'nee. F i s h . Res. Bd. Can. Trans. Ser. No. 2916. Tong, S. S. C , W. D. Young, W. H. Gutenmann, and D. J . L i s k . 1974. Trace metals i n Lake Cayuga t r o u t ( S a l v e l i n u s namaycush) i n r e l a t i o n to age. J . F i s h . Res. Board Can. 1:238-239. Vanderploeg, H. A., and J . R. Kercher. 1974. E f f e c t s of l i m n o l o g i c a l v a r i a b l e s on b i o a c c u m u l a t i o n s f a c t o r s . p. 1192-1212. In O. F. Nygaard, H. I. A d l e r and W. K. S i n c l a i r [edsTT Proceedings of the f i f t h i n t e r n a t i o n a l congress of r a d i a t i o n r e s e a r c h h e l d at S e a t t l e , Washington, U.S.A. J u l y 14-20, 1974. Vanderploeg, H. A. R. S. Boothe, and F. H. C l a r k . 1975. A s p e c i f i c a c t i v i t y model a p p l i e d to cesium movement i n an o l i g o t r o p h i c l a k e . I_n F. G. Howell, J . B. Gentry and M. H. Smith [eds.] Proceedings of a symposium on mineral c y c l i n g i n southeastern ecosystems, Augusta Georgia, May, 1974. 178 Vanderploeg, H. A., R. S. Booth, and F. H. C l a r k . 1976. A s p e c i f i c a c t i v i t y and c o n c e n t r a t i o n model a p p l i e d to cesium-137 movement i n a e u t r o p h i c l a k e . p. 164-177. In C. E. Cushing J r . [ed.] Radioecology and energy r e s o u r c e s . Proceedings of the f o u r t h n a t i o n a l symposium i n r a d i o e c o l o g y , May 12-14, 1975, Oregon S t a t e U n i v e r s i t y , C o r v a l l i s , Oregon. Werner, E. E., and D. J . H a l l . 1979. Fo r a g i n g e f f i c i e n c y and h a b i t a t s w i t c h i n g i n competing s u n f i s h e s . Ecology 60(2):256-264. W i l l i a m s , L. G. and H. D. Swanson. 1958. C o n c e n t r a t i o n of cesium-137 by a l g a e . Science 127:187-188. W i l l i a m s , L. G., and Q. P i c k e r i n g . 1961. D i r e c t and food- c h a i n uptake of cesium-137 and strotium-85 i n b l u e g i l l f i n g e r l i n g s . Ecology 42:205-206. W i n d e l l , J . T. 1978. D i g e s t i o n and d a i l y r a t i o n of f i s h e s . In S. D. Gerking [ed.] Ecology of freshwater f i s h p r o d u c t i o n . B l a c k w e l l S c i e n t i f i c P u b l i c a t i o n s . Wootton, R. J . 1976. The b i o l o g y of s t i c k l e b a c k s . Academic P r e s s , New York. Wootton, R. J . 1977. E f f e c t of food l i m i t a t i o n d u r i n g the br e e d i n g season on the s i z e , body components and egg p r o d u c t i o n of female s t i c k l e b a c k s (Gasterosteus a c u l e a t u s ) . J . Animal. E c o l . 46:823-834. Zar, J . H. 1984. B i o s t a t i s t i c a l a n a l y s i s . 2nd ed. P r e n t i c e - H a l l , Inc. new J e r s e y . 179 APPENDIX I Parameter s e t t i n g s f o r measurement of Rb and Cs Parameter Rb Cs wavelength (nm) 780.0 852. 1 s l i t (nm) 4.0 4.0 EDL (watts) 2 3.9 d r y i n g time (sec) 40 40 d r y i n g temperature °C 110 110 d r y i n g ramp (sec) 22 2.2 c h a r r i n g time (sec) 40 40 c h a r r i n g temperature °C 1000 1000 c h a r r i n g ramp (sec) 32 32 a t o m i z a t i o n time (sec) 7 7 a t o m i z a t i o n temperature °C 2400 2400 argon gas flow 80 1 80 2 s e n s i t i v i t y 3 0.0010 0.0020 ^ r g o n gas flow 7 sec normal d u r i n g a t o m i z a t i o n 2 a r g o n gas flow 3 sec i n t e r r u p t d u r i n g f i r s t stage of a t o m i z a t i o n 3 s e n s i t i v i t y i n Mg/ml f o r absorbance of 0.00044 with 20 jul i n j e c t i o n with a Perkin-Elmer As-1 autosampler 180 APPENDIX II I n t e r f e r e n c e i n measurement of Rb and Cs M a t e r i a l s and methods To c o n f i r m the s u p p o s i t i o n that s i g n a l s t r e n g t h f o r Rb and Cs was indeed suppressed at lower d i l u t i o n s , i n d i v i d u a l samples each c o n s i s t i n g of sockeye, s t i c k l e b a c k , and zooplankton t i s s u e s were d i l u t e d 25x, 75x, and 125x. Each d i l u t i o n c o n t a i n e d the same t o t a l c o n c e n t r a t i o n of Rb. Only rubidium was examined by t h i s procedure. R e s u l t s T o t a l c o n c e n t r a t i o n of Rb w i t h i n each s e r i e s of d i l u t i o n s was found to i n c r e a s e with d i l u t i o n ( F i g u r e 33 ). In the absence of a d i l u t i o n e f f e c t and experimental e r r o r , a l l c o n c e n t r a t i o n s would have y i e l d e d the same t o t a l c o n c e n t r a t i o n . T h i s r e s u l t i d e n t i f i e d a source of e r r o r i n the r e p o r t e d v a l u e s p r i o r to 1985. 181 F i g u r e 33. Changes im measured c o n c e n t r a t i o n s of Rb i n f i s h with i n c r e a s e i n d i l u t i o n . (symbols: s o c = j u v e n i l e sockeye, st=threespine s t i c k l e b a c k , zoopl=zooplankton). d i l u t i o n 183 I o n i z a t i o n i n t e r f e r e n c e I o n i z a t i o n i n t e r f e r e n c e i s a common occurrence i n flame atomic a b s o r p t i o n when d e a l i n g with elements having a low i o n i z a t i o n p o t e n t i a l such as Rb and Cs (Grobenski et a l . , 1983). In c o n t r a s t , i o n i z a t i o n i n the g r a p h i t e furnace as i n t h i s study, occurs only a f t e r the atomic a b s o r p t i o n s i g n a l has been read and t h e r e f o r e should have p r a c t i c a l l y no i n t e r f e r e n c e on the a n a l y t e s i g n a l (Grobenski et a l . 1983). I o n i z a t i o n i n t e r f e r e n c e can u s u a l l y be s o l v e d by s p i k i n g the samples and standards with an excess of the i n t e r f e r i n g element ( P r i c e , 1979). T h i s r e s u l t s i n an i n c r e a s e i n the s t r e n g t h of the s i g n a l up to a p o i n t of s a t u r a t i o n i n both the standards and the samples. T h i s procedure was a p p l i e d to the a n a l y s i s of Rb and Cs. M a t e r i a l s and methods Two s e t s of c a l i b r a t i o n standards of 25 ppb, 50 ppb and 100 ppb were d i s s o l v e d i n d i s t i l l e d d e i o n i z e d water. One s p i k e d with 1000 ppm NaCl. Sodium was chosen as i t probably i s a major ion i n a l l of the t i s s u e samples (Copeland et a l . 1972, Copeland et a l . 1973). 1 84 R e s u l t s The a d d i t i o n of NaCl r e s u l t e d i n a d e p r e s s i o n of the absorbance s i g n a l ( F i g u r e s 34 and 35). Since an i n c r e a s e i n s i g n a l s t r e n g t h would be expected from an i o n i z a t i o n problem when t r e a t e d i n the above f a s h i o n , t h i s procedure was of no c o r r e c t i v e value i n d e a l i n g with the problem. R e c a l i b r a t i o n curves C o r r e c t i o n f o r i n t e r f e r e n c e e f f e c t s was attempted by c o n s t r u c t i n g c a l i b r a t i o n curves having the same i n t e r f e r e n c e matrix as the samples but with known c o n c e n t r a t i o n s of Rb and Cs. M a t e r i a l s and methods An a r t i f i c i a l matrix was c o n s t r u c t e d f o r both zooplankton and f i s h (Tables 18 and 19). C o n c e n t r a t i o n s of major elements i n the zooplankton matrix were based on observed v a l u e s i n Lake Michigan (Copeland et a l . 1972). C o n c e n t r a t i o n s of major elements i n the f i s h matrix were based on v a l u e s f o r coho i n Lake Michigan (Copeland et a l . 1973). Four matrix c o n c e n t r a t i o n s of Rb and Cs were c o n s t r u c t e d at 185 F i g u r e 34. Standard curve f o r Rb, alone and s p i k e d with 1OOOppm NaCl. .0 . 2 0 + NaCl 0 2 0 4 0 6 0 8 0 1 0 0 Rb ppb 187 F i g u r e 35. S t a n d a r d c u r v e f o r C s , a l o n e and s p i k e d w i t h 1000 ppm N a C l . 0 . I B 0 . 1 4 0 . 1 2 A +NaCl O n o NaCl 0 . 1 0 OJ U c ro -a 0 . 0 8 c_ o cn ro 0 . 0 6 0 . 0 4 0 . 0 2 0 . 0 0 2 0 4 0 6 0 8 0 1 0 0 Cs ppb 189 Table 18. A r t i f i c i a l zooplankton matrix major elements(g) source weight > 10 ppm wt weight used (g) A l 0.99 A1 20 1 .87 Br 0.88 KBr 1.31 Ca 17.50 C a C l 2 2 H 2 0 9.74 CaC0 3 25.88 K 9.70 KBr as above KN0 3 24.04 CI 14.4 NaCl 6.76 MgCl 26H 20 20.06 C a C l 2 2 H 2 0 as above Na 2.65 NaCl as above Mg 2.40 MgCl 26H 20 as above 1 p a r t of the element i s d e r i v e d from another compound(s) l i s t e d 190 Table 19. A r t i f i c i a l f i s h matrix major elements(g) weight > 10 ppm wt weight source used(g) Ca 2.38 C a C l 2 6.48 CI 7.07 NaCl 3.53 C a C l 2 as above 1 K 35.88 KN0 3 9.27 Na 5.01 NaCl as above NaHC0 3 9.91 Mg 2.16 MgO 3.58 part of the element i s d e r i v e d from a compound(s) l i s t e d above 191 10 ppb, 25 ppb, 50 ppb, and 100 ppb. Each c o n c e n t r a t i o n was d i l u t e d 10X, 50x, 100X, and 200x. A s e r i e s of standards of 10 ppb, 25 ppb, 50ppb, and 100 ppb was a l s o prepared i n d i s t i l l e d d e i o n i z e d water. In t h i s manner the range of d i l u t i o n s observed i n the data p r i o r to 1985 was r e p r e s e n t e d . The procedure i s summarized i n Table 20. R e s u l t s R e c a l i b r a t i o n curves were p l o t t e d i n F i g u r e s 36 to 39 . 0 A s observed i n F i g u r e s 36 and 37, i n t e r f e r e n c e e f f e c t s were present at lower d i l u t i o n s . A p a r t i c u l a r f e a t u r e of the r e c a l i b r a t i o n curves was the absence of i n t e r f e r e n c e when d i l u t i o n s exceeded 100X. S e l e c t i o n of a form of an equation to f i t the data f o l l o w e d a number of s t e p s . S i n c e each c o n c e n t r a t i o n expressed a c u r v i l i n e a r response with i n c r e a s i n g d i l u t i o n , becoming asymptotic at higher d i l u t i o n s ; the c o n c e n t r a t i o n - d i l u t i o n response was f i t t e d to the e q u a t i o n : A y z = — B + y Table 20. C o n s t r u c t i o n of r e c a l i b r a t i o n curves matrix d i l u t i o n c o n c e n t r a t i o n s f a c t o r 10 25 50 100 1 Ox X X X X 50x X X X X 1 OOx X X X X 200x X X X X F i g u r e 36. R e c a l i b r a t i o n curves f o r Rb i n zooplankton. 194 0.25 cu CJ c ro n c_ o w n ro 0.20 0. 15 0 . 10 0.05 descending order ( d i l u t i o n s ) Btandard. 200X, 100X. 50X. 10X 0.0 0 20 40 60 80 100 [Fib] ppb F i g u r e 37. R e c a l i b r a t i o n curves f o r Cs i n zooplankton. 196 CD U c CO n c_ o to n co 0.25 0.20 h descending order ( d i l u t i o n s ) 0. 15 h Btandard, 200X. 100X. SOX, 10X 0. 10 0.05 0.0 h 20 40 60 80 100 [Cs] ppb 1 97 F i g u r e 38. R e c a l i b r a t i o n curves f o r Rb i n f i s h . 1 9 8 0.25 h QJ U C ro JD c_ o tn JD ro 0.20 h descending order ( d i l u t i o n s ) 200X. standards. 100X, SOX, 10X 0 . 15 0 . 10 0.05 0.0 h 0 20 40 60 80 100 [Cs] ppb 199 F i g u r e 39. R e c a l i b r a t i o n curves f o r Cs i n f i s h . d e s c e n d i n g o r d e r ( d i l u t i o n s ) s tandard , 100 X. 200 X. SOX, 10X 0 20 40 60 80 100 [Rb] ppb 201 where A and B are c o e f f i c i e n t s . C o e f f i c i e n t s A and B were determined by e x p r e s s i n g equation (1) i n l i n e a r form: 1 m — + c (2) z y where m = the slope of the r e g r e s s i o n and c the i n t e r c e p t . In terms of the o r i g i n a l c o e f f i c i e n t s of ( 1 ) , m i n e q u a t i o n (2) equals A/B and c equals 1/A. S u b s t i t u t i n g f o r c o e f f i c i e n t s A and B i n terms of slope and i n t e r c e p t i n equation ( 2 ) , e q u a t i o n (1) becomes: m y c (3) Slopes and i n t e r c e p t s were then p l o t t e d s e p a r a t e l y a g a i n s t c o n c e n t r a t i o n f o r each set of r e c a l i b r a t i o n c u r v e s . The f o l l o w i n g equations were found to d e s c r i b e the d a t a : m = A(0) + A(1 ) (4) B(0) + B(1 ) (5) 202 S u b s t i t u t i n g back i n t o e quation (3) t h i s y i e l d s : z = A(0) + A(1) + y(B(0) + B ( 1 ) (6) where z = absorbance, y = d i l u t i o n , x = c o n c e n t r a t i o n , and A(0),A(1),B(0), and B(1) are c o e f f i c i e n t s . C o e f f i c i e n t s A ( 0 ) , A(1), B(0), and B(1) were i n i t i a l l y d e r i v e d by t h i s process and were f u r t h e r r e f i n e d by m i n i m i z i n g the d i f f e r e n c e between the sum of squares of the d e v i a t i o n s of the observed and p r e d i c t e d values u s i n g a computer r o u t i n e i n Becker and Chambers (1984), (fmin program page 315). The c o e f f i c i e n t s g i v i n g the best f i t by t h i s procedure are l i s t e d i n Table 21 . A p l o t of p r e d i c t e d v a l u e s given by equation (6) a g a i n s t observed v a l u e s was i n d i c a t i v e of the h i g h l y s i g n i f i c a n t c o e f f i c i e n t s of d e t e r m i n a t i o n ( F i g u r e s 40 to 43). Past v a l u e s were a d j u s t e d by 1) determining the absorbance (abs) when i n t e r f e r e n c e was not present at d i l u t i o n f a c t o r 200x, ( o r i g i n a l standards assumed no i n t e r f e r e n c e ) , 2) d e t e r m i n i n g what t h i s absorbance should have a c t u a l l y been f o r the c o n c e n t r a t i o n and d i l u t i o n at which the sampled was measured. 203 Table 21. C o e f f i c i e n t s f o r r e c a l i b r a t i o n curves zooplankton f i s h A(0) A(1) B(0) B(1) A(0) A(1) B(0) B(1) Rubidium 19.87 5630 Cesium 15.88 4876 0.4158 440.9 -30.73 5827 0.9798 492.0 0.8151 470.4 -0.6584 3517 0.9914 453.2 C o e f f i c i e n t s of d e t e r m i n a t i o n 1 Rudidium r 2=0.96 (F=336.0, df=1,14, p<0.0l) Cesium r 2=0.92 (F=161.0, df=1,14, p<0.0l) r 2=0.75 (F=42.0, df=1,14, p<0.0!) r 2=0.92 (F=161.0, df=1,14, p<0.0l) 1 a l l h i g h l y s i g n i f i c a n t 204 F i g u r e 40. P r e d i c t e d versus observed absorbances f o r Rb- zooplankton r e c a l i b r a t i o n c u r v e s . 205 QJ CJ c ro a c_ o cn n ro QJ u T J QJ C_ Q . 0 . 18 0.16 h 0 . 14 0 . 12 0.10 h 0 . 08 h 0 . 06 h 0 . 04 0 . 02 0 . 0 0 . 0 0.05 0.10 0.15 0.20 observed absorbance 206 F i g u r e 41. P r e d i c t e d versus observed absorbances f o r Cs- zooplankton r e c a l i b r a t i o n c u r v e s . 0 . 0 0 . 05 0.10 0.15 0.20 observed absorbance 208 F i g u r e 42. P r e d i c t e d versus observed absorbances f o r R b - f i s h r e c a l i b r a t i o n c u r v e s . 209 0 . 20 QJ CJ c CD n c_ o cn JQ CD TD OJ - M U •rH " D QJ C_ Q. 0 . 15 h 0.10 h 0 . 05 h 0 . 0 0 . 0 0 . 05 0 . 10 0 . 15 0 . 20 observed absorbance 210 F i g u r e 43. P r e d i c t e d v e r s u s o b s e r v e d a b s o r b a n c e s f o r C s - f i s h r e c a l i b r a t i o n c u r v e s . 0 . 0 0 . 0 5 0 . 1 0 0 . 1 5 0 . o b s e r v e d a b s o r b a n c e

Cite

Citation Scheme:

    

Usage Statistics

Country Views Downloads
China 10 0
India 3 0
United States 2 0
Ukraine 1 0
City Views Downloads
Beijing 10 0
Unknown 4 1
Park Rapids 1 0
Ashburn 1 0

{[{ mDataHeader[type] }]} {[{ month[type] }]} {[{ tData[type] }]}

Share

Share to:

Comment

Related Items