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Effects of log storage on zooplankton and juvenile salmonids in Babine Lake, British Columbia Power, Elizabeth A. 1987

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EFFECTS OF LOG STORAGE ON ZOOPLANKTON AND JUVENILE SALMONIDS BABINE LAKE, BRITISH COLUMBIA by ELIZABETH A. POWER BSc. The Un ivers i ty Of B r i t i s h Columbia 1984 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department of Zoology) We accept t h i s thes is as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA February 1987 © E l i zabe th A. Power, 1987 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date ftfe in ( DE-6(3/81) ABSTRACT i E f f e c t s of log storage on water q u a l i t y , zooplankton and juven i le salmonids were invest igated at Babine Lake, B r i t i s h Columbia in a se r i es of enc losure , f i e l d and laboratory experiments. Enclosures were stocked with lake zooplankton and treated with lodgepole pine (Pinus  Contorta) and white spruce (Picea glauca) logs for two 25 day p e r i o d s . Oxygen d e p l e t i o n , to l e v e l s as low as 2.5 m g / l , and increased l i g n i n and tannin (L-T) concentrat ion (a measure of wood leachate) occurred in log treated enc losures . Zooplankton densi ty s i g n i f i c a n t l y decreased with increased log number, but changes in community d i v e r s i t y were not c o n s i s t e n t . In f i e l d s tudies at Morrison Arm, Babine Lake, extreme oxygen dep le t ion (<1 mg/l) was observed in l o c a l i z e d surface waters wi th in a log storage area . Dye t racer s tudies wi th in the log bundles implied reduced water movement, which may be involved in oxygen d e p l e t i o n . Loca l zooplankton abundance was usua l ly lower at log storage s i t e s than nearby undisturbed l i t t o r a l s i t e s and sockeye f ry held in s i t u for 24 h per iods acquired fewer and/or a lower d i v e r s i t y of prey items in log storage areas. Laboratory t o x i c i t y studies ind icated that spruce bark leachates were more tox ic than p ine , but l e t h a l l y tox ic bark leachates had higher L-T values than those measured in the Morrison Arm log storage area . In chronic Daphnia b ioassays , mor ta l i ty rates s i g n i f i c a n t l y increased and fecundi ty rates s i g n i f i c a n t l y decreased during long term exposure to low concentrat ions of bark leachates . Results of enclosure experiments, f i e l d studies and laboratory bioassays provide evidence that zooplankton are reduced in abundance by condi t ions which accompany log storage, p o s s i b l y through chronic t o x i c i t y or reduce fecundi ty . Because f ry d ie t was s e n s i t i v e to small changes in food abundance, there i s p o t e n t i a l for reduced s u r v i v a l of sockeye f r y exposed to low oxygen concentrat ions and reduced food l e v e l s . i i i TABLE OF CONTENTS ABSTRACT i i LIST OF TABLES iv LIST OF FIGURES v ACKNOWLEDGEMENTS . . . v i i 1. GENERAL INTRODUCTION 1 2. ENCLOSURE EXPERIMENTS 8 2.1 INTRODUCTION 8 2 .2 METHODS 11 2. 3 RESULTS 1 9 2.3.1 Bark treatments ( 1984) 19 2.3.1.1 Water qua l i t y 19 2 .3 .1 .2 . Zooplankton 21 2.3.2 Log treatments (1985) 21 2.3.2.1 Water Qual i ty 24 2.3.2.2 Zooplankton 28 2.4 DISCUSSION % 39 2.4.1 Water Qual i ty 39 2.4.2 Zooplankton 43 3. FIELD STUDY 4 7 3.1 INTRODUCTION 4 7 3.1.1 Water residence and water qua l i t y 49 3.1.2 Food supply and d ie t of sockeye f ry .51 3 . 2 METHODS 0 . 5 3 3.2.1 Water residence and water qua l i ty 53 3.2.2 Food supply and d ie t of sockeye f ry 56 3.3 RESULTS 6 2 3.3.1 Water residence and water qua l i t y 62 3.3.2 Food supply and d ie t of sockeye f ry 67 3.3.2.1 Zooplankton abundance 67 3.3.2.2 Stomach Contents 70 3.4 DISCUSSION 7 7 4. BIOASSAY EXPERIMENTS 8 7 4.1 INTRODUCTION 8 7 4.2 METHODS 9 0 4.2.1 Daphnia bioassays 9 0 4.2.1.1 Test organisms 9 0 4.2.1.2 Bark leachate so lut ions 9 1 4.2 .1 .3 Short term bioassays 9 2 4.2 .1 .4 Long term bioassays g 3 4.2.2 F i s h Bioassays 9 5 4.2.2.1 Test organisms 9 5 4.2.2.2 Short term bioassays 9 6 4.3 RESULTS 9 7 4.3.1 Bark leachate 97 4.3.2 Daphnia bioassays 97 4.3.2.1 Short term tes ts 97 4.3.2.2 Long term tes ts 99 4.3.3 F i s h bioassays 101 4.2 DISCUSSION 1 0 3 5. GENERAL DISCUSSION 1 1 0 6. REFERENCES CITED H 4 i v LIST OF TABLES Table 1. Experimental design of enclosure experiments 17 Table 2. Dissolved oxygen concentrations in enclosure experiments 26 Table 3. Percentage s i m i l a r i t y in enclosure zooplankton communities 31 Table 4 . Manova results for zooplankton abundance in enclosure experiments 32 Table 5. Water qual i t y in Morrison Arm 66 Table 6. Chemical reagents for Daphnia medium ... 91 Table 7. 96h-LC-50 values for Daphnia 99 Table 8. Proportion of Daphnxa reproducing in chronic bioassays 101 Table 9. 96h-LC-50 values for rainbow trout and sockeye salmon 103 V LIST OF FIGURES F i g u r e 1. Map of Babine Lake, B.C. Showing M o r r i s o n Arm and F u l t o n R i v e r 6 F i g u r e 2. Design of e n c l o s u r e s (volume=3700 1) 13 F i g u r e 3. D i s s o l v e d oxygen c o n c e n t r a t i o n s (mg/l) i n 1984 e n c l o s u r e experiments under bark and l o g treatments 20 F i g u r e 4. L i g n i n and t a n n i n c o n c e n t r a t i o n s (mg/l) i n 1984 e n c l o s u r e experiments 22 F i g u r e 5. T o t a l zooplankton c o n c e n t r a t i o n s ( n o . / l ) over time f o r c o n t r o l e n c l o s u r e s and e n c l o s u r e s t r e a t e d with 20 kg, 5 kg, 1 kg, and l o g r a f t treatments 23 F i g u r e 6. Oxygen s a t u r a t i o n (%) i n 1985 e n c l o s u r e experiments f o r l o g treatments and c o n t r o l s 25 F i g u r e 7. L i g n i n - t a n n i n c o n c e n t r a t i o n s i n experimental e n c l o s u r e s f o r l o g treatments and c o n t r o l s 27 F i g u r e 8. N a u p l i i and copepodite d e n s i t i e s ( n o . / l ) i n the l a k e from May 26-August 3, 1985 29 F i g u r e 9. D e n s i t i e s of D i a c y c l o p s thomasi, Diaptomus a s h l a n d i , Daphnia l o n q i r e m i s , and Bosmina cor e q o n i i n the l a k e from May 26-August 3, 1985 30 F i g u r e 10. Zooplankton d e n s i t i e s f o r common s p e c i e s i n spruce l o g t r e a t e d and c o n t r o l e n c l o s u r e s (June 2-June 26, 1985 33 F i g u r e 11. Zooplankton d e n s i t i e s f o r common s p e c i e s i n spruce l o g t r e a t e d and c o n t r o l e n c l o s u r e s ( J u l y 9-August 3, 1985 34 F i g u r e 12. Zooplankton d e n s i t i e s f o r common s p e c i e s i n pine l o g t r e a t e d and c o n t r o l e n c l o s u r e s (May 26-June 20, 1985 35 F i g u r e 13. Zooplankton d e n s i t i e s f o r common s p e c i e s i n pine l o g t r e a t e d and c o n t r o l e n c l o s u r e s ( J u l y 2-July 27, 1985 36 F i g u r e 14. D i v e r s i t y i n d i c e s f o r l o g t r e a t e d and c o n t r o l e n c l o s u r e s under a l l treatments 37 F i g u r e 15. Map of Morrison Arm, Babine Lake, B.C 48 F i g u r e 16. Sketch map of the H.F.P. Log dump bay and storage area 54 F i g u r e 17. Design of flow through e n c l o s u r e s used i n f r y f e e d i n g experiments . 58 F i g u r e 18. Dye c l o u d movement i n s u r f a c e waters w i t h i n l o g bundles 64 F i g u r e 19. Depth d i s t r i b u t i o n and d i l u t i o n of dye c l o u d ....65 F i g u r e 20. Zooplankton abundance i n flow through e n c l o s u r e s a t boom and c o n t r o l s i t e s d u r i n g sockeye feeding experiments May 22-23 and May 28-29, 1985 69 F i g u r e 21. Zooplankton abundance i n flow through e n c l o s u r e s at ramp and c o n t r o l s i t e s d u r i n g sockeye fee d i n g experiments June 4-5, 1985 71 F i g u r e 22. Stomach f u l l n e s s and number of prey i n stomachs of sockeye f r y d u r i n g f e e d i n g experiments at boom and v i cont ro l s i t e s and at ramp and cont ro l s i t e s 73 Figure 23. Gut contents for sockeye fry held at boom and 'control s i t e s and ramp and cont ro l s i t e s 75 Figure 24. D ive rs i t y indices for gut contents of sockeye f ry held at boom, ramp and cont ro l s i t e s 76 Figure 25. Example of graphica l in te rpo la t ion for c a l c u l a t i o n of 96h-LC-50 93 Figure 26. L ign in - tann in concentrat ions produced over time under s t a t i c condi t ions for Daphnia and f i s h bioassays ..98 Figure 27. Surv iva l of Daphnia neonates in chronic bioassays for spruce and pine bark leachates 100 Figure 28. Mean t o t a l number of neonates produced per reproducing Daphnia in sublethal bioassays with s e r i a l d i l u t i o n s of spruce and pine bark leachate 102 v i i ACKNOWLEDGEMENTS I wish to express s i n c e r e thanks t o my s u p e r v i s o r , Dr. Tom Northcote, f o r h i s enthusiasm and guidance d u r i n g the course of t h i s study. I am a l s o g r a t e f u l to my r e s e a r c h committee members, Drs. W.E. N e i l l , C.J. Walters and K.J. H a l l , f o r t h e i r a d v i c e and prompt c r i t i c a l reviews of the manuscript. Dr. C. Magnhagen a l s o gave comments on s e c t i o n s of t h i s work. Dr. K.J. H a l l , David Levy and Itsuo Yesaki p r o v i d e d l o g i s t i c a l support and a l i n k to U.B.C. d u r i n g f i e l d seasons. Thanks are a l s o due to Paula W e n t z e l l f o r her able a s s i s t a n c e throughout the e n c l o s u r e study. The support and p a t i e n c e of my f r i e n d s , both w i t h i n and ou t s i d e of the u n i v e r s i t y , i s a p p r e c i a t e d beyond measure. S p e c i a l thanks are a l s o extended t o the c i t i z e n s of G r a n i s l e , B r i t i s h Columbia f o r welcoming me i n t o t h e i r community. Susan L i p t a k and Paula Parkinson of the Environmental E n g i n e e r i n g Laboratory, U.B.C are acknowledged f o r t h e i r a s s i s t a n c e with water q u a l i t y a n a l y s e s and Daphnia b i o a s s a y s . The Department of F i s h e r i e s and Oceans k i n d l y p r o v i d e d me with l a b o r a t o r y f a c i l i t i e s a t F u l t o n R i v e r Spawning Channel. Dr. A. Kozak ( F o r e s t r y ) and C. L a i (U.B.C. computing c e n t r e ) a s s i s t e d with s t a t i s t i c a l a n a l y s i s . Research funds were s u p p l i e d by Houston F o r e s t Products i n a grant (funded under S e c t i o n 88.2 of the B.C. F o r e s t Act) to The Westwater Research Centre. The Science C o u n c i l of B.C. pro v i d e d p e r s o n a l f i n a n c i a l support through a G.R.E.A.T. s c h o l a r s h i p . F i n a l l y , I would l i k e t o thank my f a m i l y f o r t h e i r unceasing moral support. 1 1. GENERAL INTRODUCTION Over 90% of the timber logged from B r i t i s h Columbia's fores ts spends time in water-based systems of t ransportat ion and storage (Edgel l and Ross 1983) en route to processing m i l l s . Log handling a c t i v i t i e s represent one of the la rgest costs to the forest indust ry . H i s t o r i c a l l y , wood has always been harvested from the most access ib le places f i r s t , such as along the shores of seas, r i v e r s and lakes; consequently water-based log handling systems were developed (Sedel l and Duval 1985). Log d r i v ing ( t ransportat ion of wood using the power of r i v e r water flow) was a common prac t i ce which caused extreme damage to r i ve r hab i ta ts , p a r t i c u l a r l y spawning and juveni le rear ing areas ( I . P . S . F . C 1966). In the la te 1800s, r i v e r improvement consisted of removing obstacles from r i v e r s , s t ra ightening out crooked streams and blocking of f sloughs and marsh areas with c r ibb ing to keep water and logs in the main channel (Sedel l and Duval 1985). Present ly , water-based log handling centres around dumping, sor t ing and storage a c t i v i t i e s . Most of the s i t e leases are concentrated in shal low, protected areas such as bays and estuar ies which are perceived as sens i t i ve to manipulation by man. This concern i s evidenced by a number of recent studies commissioned to look at the e c o l o g i c a l aspects of log storage, 2 p a r t i c u l a r l y i n es t u a r i n e environments (Anon. 1980a, Anon. 1981, Levy et a l . 1982). There are many aspects of l o g handling i n water which may adversely a f f e c t the environment. Recognized e f f e c t s of log storage on f i s h h a b i t a t f a l l s i n t o three c a t e g o r i e s : p h y s i c a l e f f e c t s , chemical e f f e c t s and b i o t i c e f f e c t s . The most obvious and w e l l documented impacts of l o g handling on the aquatic environment are p h y s i c a l changes (eg. bark d e p o s i t i o n , sediment compaction, and increased water t u r b i d i t y ) (Toews and Brownlee 1981). Chemical changes to water q u a l i t y induced by l o g storage have been q u a n t i f i e d i n l a b o r a t o r y s t u d i e s (Graham 1970, Atkinson 1971). Leachate e x t r a c t i o n occurs i n water and i s accompanied by increased C.O.D. (chemical oxygen demand), B.O.D. ( b i o l o g i c a l oxygen demand) and oxygen d e p l e t i o n . L i t e r a t u r e on impacts of l o g storage on b i o t a i s mainly d e s c r i p t i v e ; s e v e r a l reviews and summary p u b l i c a t i o n s have been produced, a l l of which c o n t a i n the same information (Anon. 1980a, E d g e l l and Ross 1983, S e d e l l and Duval 1985). In a recent review of l o g handling i n B r i t i s h Columbian e s t u a r i e s , the Environmental Review Panel (Anon. 1980a, p 6) st a t e d : P a r t i c u l a r l y c r i t i c a l i s the need f o r information on the p r e c i s e i n t e r a c t i o n between f i s h e s and environments used f o r log handling. Lack of data on the impact of l o g handling on c o a s t a l ecosystems cannot be ove r s t a t e d . 3 There are data on e f f e c t s of l o g storage on benthic i n v e r t e b r a t e s (Conlan 1975, Conlan and E l l i s 1979, Levy et a l . 1985b) from which p r e d i c t i o n s about the food supply of b e n t h i c a l l y feeding f i s h can be made. However, wi t h the exception of a s i n g l e study on the Fraser R i v e r estuary (Levy et a l . 1982), no published information e x i s t s on d i r e c t e f f e c t s of log storage on f i s h populations (Ainscough 1979, Anon. 1980a). This lack of information places h a b i t a t managers i n an awkward p o s i t i o n . In Coos Bay, Oregon, U.S.A., government b i o l o g i s t s set s t r i n g e n t l o g handling water p o l i c i e s i n 1979, and were placed under co n s i d e r a b l e pressure from the f o r e s t i n d u s t r y because they lacked data t o support t h e i r b e l i e f that l o g r a f t s were a f f e c t i n g f i s h production d e t r i m e n t a l l y (M. Brownlee, pers. comm.). In the Nanaimo estuary, f e d e r a l b i o l o g i s t s found themselves i n a s i m i l a r p o s i t i o n , which r e s u l t e d i n formation of a task force to examine the s i t u a t i o n (Anon. 1980b). When Houston Forest Products (H.F.P.) obtained r i g h t s to harvest timber i n f e c t e d by spruce budworm near Morrison Arm, Babine Lake, B.C. (55 deg.N, 123 deg. W), they a p p l i e d to i n s t a l l a l o g storage and t r a n s p o r t a t i o n system on the l a k e . O f f i c i a l s from the Department of F i s h e r i e s and Oceans expressed concern about p o t e n t i a l d e l e t e r i o u s e f f e c t s on Babine Lake and 4 gave cond i t iona l approval , provided that a 3 year study be implemented to determine the e f fec ts of log handling on the f i s h habi ta ts and populat ion of Babine Lake. The Westwater Research Centre received a grant from H . F . P . (funded under Sect ion 88.2 of the B .C . Forest Act) to undertake the study. The main ob ject ive of the study was to "determine the e f f e c t s of log dumping, storage, and dewatering on f i s h rear ing and spawning habi tat and migration routes of f r y , smolts, and adul ts at s p e c i f i c use s i t e s , inc lud ing those to be used by H . F . P . , and the p o t e n t i a l impact on Babine Lake f i s h e r i e s " (Levy et a l . 1984, p. 1). Babine Lake i s the largest natural lake in B r i t i s h Columbia and one of the major drainage basins for the Skeena River system (Johnson 1965, Levy and Ha l l 1985). Sockeye salmon ( Oncorhynchus nerka the Babine system contr ibute over 90% of the Skeena sockeye f i s h e r y (Larkin and McDonald 1968). Average production (over past 30 y r . ) of adult sockeye has been about 1.5 m i l l i o n annually (McDonald and Hume 1984). H . F . P . i n s t a l l e d two log handling f a c i l i t i e s at Babine Lake (Figure 1). At the head of Morrison Arm a log dump/storage s i t e was i n s t a l l e d which i s used from the time of freeze up to ear ly summer. Log bundles from winter logging are s l i d down a ramp into the water and then stored in a small bay kept ice free with an a i r bubbler system u n t i l spr ing ice break up. Then the log 5 bundles are towed i n large r a f t s to the dewatering s i t e near F u l t o n River (Figure 1). There, l o g bundles are loaded onto logging t r u c k s and taken to a m i l l . Impacts of logging a c t i v i t i e s along the shore of Babine Lake w i l l p o t e n t i a l l y be greatest i n s h e l t e r e d l i t t o r a l areas of Morrison Arm where logs are s t o r e d . Poor water c i r c u l a t i o n and wood leachate e x t r a c t i o n may combine to produce d e l e t e r i o u s water c o n d i t i o n s f o r sockeye salmon f r y and t h e i r food supply, zooplankton. To examine t h i s p r e d i c t i o n , enclosure, f i e l d and l a b o r a t o r y experiments were designed to examine e f f e c t s of log storage c o n d i t i o n s on zooplankton and f i s h . A l o c a l i z e d reduction i n food supply f o r r e c e n t l y emerged f r y may r e s t r i c t t h e i r growth during t h i s " c r i t i c a l " p e r i o d , according to H j o r t (1914) and Braum (1967). To t e s t the hypothesis that zooplankton abundance decreases under simulated lo g storage c o n d i t i o n s , enclosures with stocked zooplankton populations were t r e a t e d w i t h l o g s . Then water q u a l i t y and zooplankton abundance and d i v e r s i t y were monitored over time (Chapter 2 ) . To complement the enclosure s t u d i e s of water q u a l i t y and zooplankton, comparative monitoring was c a r r i e d out f o r water q u a l i t y and zooplankton abundance at log storage and undisturbed l i t t o r a l f i e l d s i t e s (Chapter 3). 6 7 I examined feeding by sockeye f ry held at log storage and undisturbed l i t t o r a l s i t e s to test for d i f fe rences in food intake over 24 h periods between the two areas (Chapter 3) . Ration l e v e l and growth rate in sockeye salmon are cor re la ted (Brett et a_l. 1969) and i t was expected that small sockeye f ry would experience morta l i ty and hence higher morta l i ty rates (West 1983) in d isturbed s i t e s . To determine the wood leachate l eve ls necessary to a f fec t zooplankton negat ive ly , l e t h a l and chronic laboratory bioassays were conducted (Chapter 4) . It i s known that wood and bark leachates are tox ic (Atkinson 1971, Buchanan et a l . 1976) but at l e v e l s higher than those which usua l ly occur in log storage areas . Therefore , chronic bioassays for Daphnia were used to test for subletha l e f f e c t s of low concentrat ions of leachate . 8 2. ENCLOSURE EXPERIMENTS 2 . J , INTRODUCTION Most r e s e a r c h on the b i o t i c e f f e c t s of l o g storage i s mainly d e s c r i p t i v e or q u a l i t a t i v e and c o n c e n t r a t e s on b e n t h i c i n v e r t e b r a t e s . P h y s i c a l impacts, such as sediment compaction and bark d e p o s i t i o n , as w e l l as chemical changes i n the environment (reduced oxygen, hydrogen s u l p h i d e and t o x i c wood le a c h a t e p r o d u c t i o n ) are r e s p o n s i b l e f o r d e p l e t i o n of b e n t h i c communities (Toews and Brownlee, 1981). However, no r e s e a r c h has been done on the e f f e c t s of l o g storage on p e l a g i c i n v e r t e b r a t e s such as zooplankton i n marine, e s t u a r i n e or f r e s h water systems. One might not expect these organisms to be a f f e c t e d by l o g storage because zooplankton move with water masses. Yet almost h a l f of B r i t i s h Columbia's l o g h a n d l i n g l e a s e s are f o r s i t e s with n e g l i g i b l e t i d a l c u r r e n t s (FERIC 1980) which i n c r e a s e s the p o t e n t i a l f o r chemical impacts on i n v e r t e b r a t e s i n the water column. C e r t a i n l y , Levy e_t a l . (1985) and the present study (Chapter 3) have demonstrated t h a t severe oxygen d e p l e t i o n can occur i n a l o g storage area w i t h i n a very s h o r t time. There i s concern about l o c a l i z e d r e d u c t i o n of food supply f o r p l a n k t i v o r o u s f i s h e s , p a r t i c u l a r l y commercially important s p e c i e s such as sockeye salmon, whose j u v e n i l e l i f e stages depend l a r g e l y upon lake zooplankton (Narver 1970, Rankin 1977). Sockeye f r y from Morrison Creek seem to stay inshore f o r a few 9 days as they move down the arm and then o f f s h o r e (Levy et a l . 1985b). When l i t t o r a l p o s t l a r v a l sockeye enter the Morrison Arm lo g storage grounds, they are o f t e n j u s t beginning t o feed on zooplankton ( p e r s . o b s . ) . H j o r t (1914) and Braum (1967) suggest that the most c r i t i c a l p e r i o d f o r l a r v a l f i s h i s du r i n g the t r a n s i t i o n from y o l k sac to e x t e r n a l f e e d i n g . A food shortage d u r i n g t h i s time may induce s t a r v a t i o n because young f i s h are l e a s t r e s i s t a n t t o low energy r e s e r v e s . While bioassay data are i n d i s p e n s i b l e i n a s s e s s i n g r e l a t i v e t o x i c i t i e s and p r o v i d i n g b a s e l i n e data, they do not adequately assess the long term impact of a t o x i c a n t on a n a t u r a l community assemblage (Leeuwangh 1978, Stephenson et a l . 1984). A l t e r n a t i v e l y , f i e l d s t u d i e s encounter the inherent d i f f i c u l t y of r e p e t i t i v e l y sampling the same p o p u l a t i o n of organisms i n the same water mass over time (Gamble and Davies 1982) and they o f t e n l a c k adequate c o n t r o l s . The need i n t o x i c o l o g y , and a q u a t i c ecology i n g e n e r a l , f o r w e l l c o n t r o l l e d experiments on complex systems has l e d to the use of iji s i t u e n c l o s u r e s which i s o l a t e p a r t of the water column and allow w e l l c o n t r o l l e d m a n i p u l a t i o n s . A r t i f i c i a l l y impounded p o p u l a t i o n s a re h e l d under c o n t r o l l e d c o n d i t i o n s so t h a t treatment e f f e c t s can be d i s c e r n e d ( G r i c e and Menzel 1978, G r i c e and Reeve 1982, Stephenson et a l . 1984). Buikema et a l . (1982) p o i n t out t h a t s i n c e the goal of most environmental s t u d i e s i s to examine e f f e c t s on the e n t i r e community, microcosm (<10 cu b i c meters, Banse 1982) t e s t s may be the most a p p r o p r i a t e method f o r p r e d i c t i o n . 10 Microcosms have been widely used t o e v a l u a t e the environmental impacts of a q u a t i c p o l l u t a n t s (Banse 1982). Large v a r i a t i o n i n zooplankton p o p u l a t i o n d e n s i t y and s p e c i e s composition make i t d i f f i c u l t t o d e t e c t long term e f f e c t s of p o l l u t a n t s i n the f i e l d (Kuiper 1982). The use of e n c l o s u r e s i n a d d i t i o n t o sho r t term b i o a s s a y s permits the i n c l u s i o n of e f f e c t s from n a t u r a l b i o t i c f a c t o r s which may i n f l u e n c e the outcome of the t o x i c i t y experiment (Kaushik et a l . 1985, S a l k i et a l . 1985), but cannot be i n c l u d e d i n l a b o r a t o r y s i t u a t i o n s . Experimental e n c l o s u r e s were used to examine e f f e c t s of bark and l o g treatments on water q u a l i t y and zooplankton d e n s i t y i n the l i t t o r a l zone of Babine Lake. D e t e r i o r a t i o n of water q u a l i t y and reduced zooplankton d e n s i t y under l o g treatment, r e l a t i v e t o c o n t r o l e n c l o s u r e s , w i l l be accepted as evidence t h a t l o g storage can d e t r i m e n t a l l y a f f e c t the l o c a l i z e d environment t h a t sockeye salmon f r y i n h a b i t f o r t h e i r f i r s t weeks of l i f e . Decreased d i v e r s i t y i n zooplankton p o p u l a t i o n s exposed t o t o x i c a n t s has been used as an i n d i c a t o r of d e l e t e r i o u s e f f e c t s (Washington 1984, Kaushik 1985). I p r e d i c t t h a t zooplankton d i v e r s i t y w i l l decrease over time i n l o g t r e a t e d e n c l o s u r e s and 5 l o g treatment p o p u l a t i o n s w i l l have the lowest d i v e r s i t i e s . ; More s p e c i f i c a l l y , four main q u e s t i o n were addressed: (1) are there d i f f e r e n c e s i n the e f f e c t s of the two main commercial 11 t r e e s p e c i e s , Pine ( Pinus c o n t o r t a ) and spruce ( Picea glauca ) on water q u a l i t y and zooplankton d e n s i t y ? and (2) at what point does the r a t i o of wood t o water, or logs per enclosure, s i g n i f i c a n t l y reduce lake zooplankton d e n s i t i e s ? (3) are there d i f f e r e n t i a l e f f e c t s on the d i f f e r e n t zooplankton species and l i f e h i s t o r y stages? and (4) do log treatments reduce the species d i v e r s i t y of zooplankton i n enclosures, i n d i c a t i n g a change i n community s t r u c t u r e ? This chapter i s based mainly on log treatment experiments conducted during the 1985 f i e l d season. R e s u l t s from bark a d d i t i o n experiments w i l l be b r i e f l y presented and discussed w i t h respect to general trends. 2.2 METHODS Enclosure experiments were conducted i n waters of a depth s i m i l a r t o that of a shallow boom s i t e (z=3 m), w i t h i n a prot e c t e d l i t t o r a l area at G r a n i s l e , Babine Lake. Eight i d e n t i c a l enclosures were b u i l t during the summer of 1984. The enclosures c o n s i s t e d of two p a r t s : a p l a s t i c bag and a f l o a t from which the bag was suspended (Figure 2 ) . The bags were made of a woven p o l y o l e f i n f a b r i c (Fabrene R Type "T.M.") and were sewn by Fal s e Creek I n d u s t r i e s L t d . i n t o a c y l i n d e r 1.5 m in diameter and 2.1 m i n depth (Volume = 3700 1 ) . The enclosures had a s o l i d bottom; there was no water exchange or contact with 12 lake sediment. The f l o a t was of plywood c o n s t r u c t i o n ; buoyancy was p r o v i d e d by styrofoam b l o c k s . The bag was suspended from the i n s i d e perimeter of the f l o a t and l a c e d i n t o p l a c e . The tops of the e n c l o s u r e s extended 0.3 m above the s u r f a c e of the water to minimize water s p i l l o v e r . Procedure: E n c l o s u r e s were f i l l e d by water pump wit h lake water taken over a 0 to 2.0 m depth range. During the 1984 f i e l d season, zooplankton were pumped with t h i s water d i r e c t l y i n t o the e n c l o s u r e s and d i f f i c u l t i e s were encountered i n i n i t i a l l y s t o c k i n g the e n c l o s u r e s with s i m i l a r zooplankton p o p u l a t i o n s . T h e r e f o r e , d u r i n g the 1985 f i e l d season, the e n c l o s u r e s were stocked with zooplankton independently i n a method suggested by W.E. N e i l l ( p e r s . comm. 1985). The water pumped i n t o each e n c l o s u r e was f i l t e r e d through a 100 micrometer mesh net to remove zooplankton. E n c l o s u r e s were then stocked with zooplankton obtained from v e r t i c a l h a u l s from 4.0 m to s u r f a c e . The f o l l o w i n g formula was used to c a l c u l a t e the number of v e r t i c a l h a u l s r e q u i r e d per e n c l o s u r e : no. h a u l s = volume of e n c l o s u r e volume of haul X net e f f i c i e n c y The e f f i c i e n c y of the zooplankton net used t o stock the en c l o s u r e s was compared to a PAR diaphragm b i l g e pump and found to be (1) e q u a l l y e f f i c i e n t f o r sampling both n a u p l i i and copepodites (2) 30% more e f f i c i e n t f o r sampling D i a c y c l o p s plywood Figure 2. Design of enclosures (volume = 3700 1). 14 a d u l t s and (3) 20% l e s s e f f i c i e n t f o r sampling Diaptomus a d u l t s . O v e r a l l , there was no net d i f f e r e n c e i n e f f i c i e n c y between the zooplankton net and the pump f o r sampling the e a r l y May zooplankton p o p u l a t i o n . T h e r e f o r e , assuming t h i s t o be t r u e , the number of haul s to stock one e n c l o s u r e was c a l c u l a t e d to be 20 hau l s from 4 m to s u r f a c e . To t e s t t h i s r e s u l t , a t r i a l zooplankton s t o c k i n g experiment was conducted; the t r i a l e n c l o s u r e was understocked, p a r t i c u l a r l y f o r a d u l t l i f e s t a g e s . T h e r e f o r e , to reach l a k e d e n s i t i e s of zooplankton, 100 v e r t i c a l h a u l s (4 m to s u r f a c e ) were mixed and randomly a l l o c a t e d over the four e n c l o s u r e s used f o r each experiment. The percentage s i m i l a r i t y between e n c l o s u r e s was c a l c u l a t e d to a s s ess r e l a t i v e i n i t i a l c o n d i t i o n s . I was aiming f o r a percentage s i m i l a r i t y of 80% or b e t t e r . Renkonen's index, m o d i f i e d with a n a t u r a l l o g t r a n s f o r m a t i o n , as suggested by WoIda (1981), was used. R E N K O N E N S ' S INDEX OF S I M I L A R I T Y P . S . = m i n ( p j j , p 2 j . ) a f t e r I n ( n j j n 2 j ) w h e r e = p r o p o r t i o n o f t d t a l n o . o f i n d i v i d u a l s c o n s i s t i n g o f t h e j t h t y p e n , . = n o . o f i n d i v i d u a l s o f 1 J t h t h e j t y p e 15 Water q u a l i t y and zooplankton were sampled p r i o r to the i n t r o d u c t i o n of l o g r a f t s (day 0) and then c o n s e c u t i v e l y , on days 5, 10, 15, 20, and 25 of each experiment. D i s s o l v e d oxygen (D.O.) and temperature were determined iri s i t u w ith a YSI (model 57) d i s s o l v e d oxygen/temperature meter. The oxygen probe was c a l i b r a t e d at the beginning of each sample day by the a i r s a t u r a t i o n method and a l t i t u d e c o r r e c t e d . A l l measurements were taken at 1 m depth i n the centre of the enclosures. Lake samples of water q u a l i t y and zooplankton were taken adjacent to the enclosures on every sample date. Water samples were frozen and then l a t e r analyzed f o r l i g n i n and tannin (L-T) c o n c e n t r a t i o n . L i g n i n s and tannins contain aromatic hydroxyl groups that reduce tuhgstophosphoric and molybdophosphoric a c i d s to form a blue c o l o u r . The colour absorbence determined w i t h a spectrophotometer (APHA et a l . 1985) gives a measure of l i g n i n and tannin c o n c e n t r a t i o n s . Water q u a l i t y data were obtained c o o p e r a t i v e l y with Paula W e n t z e l l , a c i v i l engineering graduate student. To assess the zooplankton populations i n the enclosure experiments and l a k e , samples were taken by pumping f o r one minute (37 1) from 1 m i n depth, w i t h the pump outflow passing through a 100 micrometer net. D u p l i c a t e samples were taken f o r each treatment. Samples were preserved i n a sucrose formaldehyde s o l u t i o n (Haney and H a l l 1975) and enumerated and i d e n t i f i e d under a stereo d i s s e c t i n g scope using Edmondson (1959) and Smith 16 and Fernando (1978) f o r taxonomic c l a s s i f i c a t i o n . Most samples were completely counted; subsampling was used f o r abundant organisms o n l y . The l o g s used i n the experiments were approximately 1.4 m long and 0.15 m i n diameter. They were cut two weeks p r i o r to the s t a r t of each experiment and t i e d t o gether i n r a f t s before being i n t r o d u c e d i n t o e n c l o s u r e s . A f t e r completion of an experiment, the l o g s were measured and then the bark was removed f o r dry weight d e t e r m i n a t i o n . E n c l o s u r e s were emptied and scrubbed c l e a n between experiments. Experimental Design; In 1984, only four e n c l o s u r e s were c o n s t r u c t e d i n i t i a l l y . P a i r s of e n c l o s u r e s were used f o r t r e a t m e n t / c o n t r o l combinations. Treatments were randomly a p p l i e d to s i n g l e e n c l o s u r e s and c o n s i s t e d of amounts of bark (60:40 r a t i o of p i n e : s p r u c e by weight); 20 kg, 5 kg and 1 kg bark weights were used f o r c o n s e c u t i v e 31, 14 and 12 day experiments, r e s p e c t i v e l y . A l s o , a r a f t of 8 l o g s was used as an experimental treatment f o r t h r e e weeks i n a s i n g l e e n c l o s u r e to simulate a l o g bundle. Water q u a l i t y and zooplankton were monitored over the 2, 3 and 4 week experiments. These experiments p r o v i d e d i n f o r m a t i o n which was used f o r experimental design of the 1985 f i e l d season. The 1985 e n c l o s u r e experiments were designed to t e s t e f f e c t s over time of l o g s of two t r e e s p e c i e s on the l i t t o r a l 17 zooplankton populat ion of Babine Lake. Treatments of tree species (pine and spruce) and log number (0, 1, 3 and 5 per enclosure) were examined using eight experimental enclosures with one rep l i ca te for each log number and tree species combination. Log treatments corresponded to loading d e n s i t i e s of 0 ( c o n t r o l ) , 0.0067, 0.0201 and 0.0335 cubic meters wood/ cubic meter water. Log number treatments were randomly assigned to the four enclosures used for each of pine and spruce treatments. Experiments were run twice, each for a length of 25 days, as out l ined in Table 1. This experimental design d id not provide true r e p l i c a t i o n because experiments were repeated at d i f f e ren t times (Hurlbert 1984). Table 1. Experimental design and times of 1985 enclosure Tree species Dupl icate Experiment dates pine 1 May 26 - June 20, 1985 pine 2 July 2 - Ju ly 27, 1985 spruce 1 June 2 - June 27, 1985 spruce 2 Ju ly 9 - August 3, 1985 S t a t i s t i c a l a n a l y s i s : The e f fec ts of the log treatments on enclosure zooplankton populat ions were assessed using SPSS:X MANOVA which i s a genera l ized mul t ivar ia te ana lys is of variance program that can analyze repeated measures designs (SPSS:X User ' s Guide 1983). 18 When the same experimental u n i t ( i n t h i s case, zooplankton i n d i v i d u a l s w i t h i n e n c l o s u r e s ) i s observed r e p e a t e d l y under a l l treatments, the design i s c a l l e d repeated measures (Winer 1962). T h i s approach p r o v i d e s c o n t r o l f o r i n d i v i d u a l d i f f e r e n c e s among experimental u n i t s i n t h e i r responsiveness to treatments (which may be a r e s u l t of i n i t i a l c o n d i t i o n s ) and p r o v i d e s a more powerful t e s t of the e f f e c t s of treatment f a c t o r s when i n t e r s u b j e c t v a r i a b i l i t y i s hig h ( H a r r i s 1975). I used a three-way MANOVA with repeated measures t o t e s t the June and J u l y , 1985 data f o r the main e f f e c t s of t r e e s p e c i e s , l o g number and zooplankton s p e c i e s and t h e i r i n t e r a c t i o n s . Sample date i s c o n s i d e r e d a repeated f a c t o r and t h i s a n a l y s i s does not depend on these dates being independent of one another (Winer 1962). E s s e n t i a l l y , a l t h o u g h a l l sample dates are used, the number of deg. of freedom does not i n c r e a s e . A l l data on zooplankton d e n s i t y were log(x+1) transformed before I conducted MANOVA t e s t s ; t h i s reduced h e t e r o g e n e i t y among groups and normalized d i s t r i b u t i o n s as determined by SPSS:X subcommands. A p r i o r i t e s t s f o r d i f f e r e n c e s between l e v e l s of s i g n i f i c a n c e f o r main e f f e c t s were examined u s i n g the c o n t r a s t (p=0.05) subcommand. Simpsons's D i v e r s i t y I n d i c e s (Washington, 1984) were c a l c u l a t e d f o r the zooplankton i n each e n c l o s u r e f o r every sample date u s i n g the formula: 1 9 SIMPSON'S D I V E R S I T Y INDEX ( D ) s D = 1 - ( P i ) 2 1=0 w h e r e s P i 2.3 RESULTS 2.3.1 Bark treatments (1984) 2.3.J_.J_ Water q u a l i t y D i s s o l v e d oxygen c o n c e n t r a t i o n s were d r a m a t i c a l l y reduced over time i n bark t r e a t e d e n c l o s u r e s ( F i g u r e 3 ) , and t h i s e f f e c t i n c r e a s e d with the amount of bark added. The e i g h t l o g treatment a l s o depressed oxygen to < 1 mg/l w i t h i n 14 days. L i g n i n and t a n n i n c o n c e n t r a t i o n of e n c l o s u r e water i n c r e a s e d over time i n a l l bark treatments, p a r t i c u l a r l y f o r 20 kg ( F i g u r e 4 ) . The e i g h t l o g treatment e n c l o s u r e water reached a L-T c o n c e n t r a t i o n s l i g h t l y above 4 mg/l which was lower than = n o . o f s p e c i e s = p r o p o r t i o n o f t o t a l n o . o f i n d i v i d u a l s o f 1 t h s p e c i e s DISSOLVED OXYGEN -ALL TREATMENTS A J , - , 1 1 1 r-0 5 10 15 20 25 SO TIME (days) gure 3. D issolved oxygen concentrat ions (mg/l) in 1984 enclosure experiments under bark and log treatments (see legend). 21 measured for a l l bark treatments. 2 .3 .J_ .2 . Zooplankton I n i t i a l zooplankton d e n s i t i e s among enclosures and between lake and enclosure populat ions were d i s s i m i l a r , which makes comparisons d i f f i c u l t . However, several trends were c lea r from which dec is ions about the 1985 f i e l d season could be made. Under the 20 kg bark treatment, t o t a l zooplankton abundance decreased s i g n i f i c a n t l y within the f i r s t week of exposure to the point where no zooplankton survived the l a s t two weeks of the experiment (Figure 5 ) . In the cont ro l enc losure , zooplankton •v. populat ions were maintained throughout the experiment. Zooplankton d e n s i t i e s decreased in the 5 kg bark treatment to l e v e l s below those measured in the c o n t r o l . However, in the 1 kg treatment, where i n i t i a l condi t ions were d i s s i m i l a r , con t ro l zooplankton populat ions dec l ined s u b s t a n t i a l l y during the experiment and the treatment populat ion increased s l i g h t l y . Zooplankton populat ions exposed to the 8 log treatment dec l ined in densi ty to zero , but cont ro l populat ions a lso decreased to extremely low l e v e l s . 2 . 3 . 2 Log treatments (1985) 22 400-i TIME (days) 30-i Figure 4. L ign in and tannin concentrat ions (mg/l) in 1984 enclosure experiments under for a l l treatments (top) and a l l treatments excluding 20 kg bark load (bottom). 23 Total Zooplankton Abundance : 20kg Total Zooplankton Abundance : 1kg Total Zooplankton Abundance : 5KG Total Zooplankton Abundance : Logs JOT Figure 5 . Tota l zooplankton concentrat ions ( n o . / l ) over time for cont ro l enclosures and enclosures treated with 20 kg, 5 kg, and 1 kg of bark, and a log raf t in 1984. 24 2.3.2 .J_ Water Qual i ty Temperatures in the enclosures stayed within 1 degree C of lake temperatures adjacent to the enclosures. Water temperature during the June, 1985 experiments ranged from 4.1 to 12.0 deg. C; in the J u l y , 1985 experiments water temperature ranged from 13.0 to 17.5 deg. C. D issolved oxygen concentrat ion was reduced in log treated enc losures , compared to the lake and c o n t r o l s , but to a far greater degree in Ju ly than in June (Table 2 ) . Oxygen deplet ion increased s i g n i f i c a n t l y with time and with the number of logs per enc losure . Pine log treatments reduced d isso lved oxygen concentrat ions to s l i g h t l y lower l e v e l s than "spruce, p a r t i c u l a r l y in J u l y . The oxygen saturat ion percentages (measured d isso lved oxygen concentrat ion d iv ided by oxygen saturat ion concentrat ion ( Y . S . I . instrument book) for the appropriate water temperature) are presented in Figure 6. Oxygen saturat ion percentages remained near 100% in contro l and 1 log enc losures , but dec l ined to 80% and <40% in 5 log treatments for June and J u l y , r e s p e c t i v e l y . L ign in and tannin concentrat ions of enclosure water increased s i g n i f i c a n t l y with time and with the number of logs per treatment (Figure 7) and there was no apparent d i f fe rences O) E PINE MAY 26-JUNE 20 Z /.^!~ z < r-I 5 10 15 20 TIME (days) SPRUCE JUNE 2-JUNE 27 Control 1 log 3 logs ' 5 logs ' JULY 9-AUGUST 3 C T ^ — • • • — 25 0 I I I I 5 10 15 20 TIME (days) 25 Figure 6. Oxygen saturat ion (%) in 1985 enclosure experiments for log treatments and con t ro ls (see legend). 26 Table 2. Dissolved oxygen concentrat ions (mg/l) in experimental enclosures for log treatments, lake , and cont ro ls (treatment; C = c o n t r o l , 1 = 1 l o g , 3 = 3 l o g s , 5 = 5 logs NUMBER OF DAYS Treatment Dupl icate 0 5 10 15 20 25 lake 1 10. 7 1 1 . 3 11 . 0 10. 4 10. 2 1 1 . 1 pine C 1 11 . 6 1 1 . 1 1 1 . 4 10. 7 10. 4 9. 8 pine 1 pine 3 1 12. 4 10. 8 1 1 . 2 10. 1 9. 5 9. 6 1 1 1 . 1 10. 0 9. 3 8. 8 8. 6 9. 5 pine 5 1 1 1 . 5 9. 7 8. 4 8. 2 8. 0 9. 1 lake 2 10. 1 9. 4 9. 4 9. 7 9. 3 8. 9 pine C pine 1 2 10. 3 9. 4 9. 3 9. 6 9. 0 9. 0 2 10. 4 9. 2 8. 5 8. 9 7. 8 8. 0 pine 3 2 10. 3 8. 2 6. 8 5. 8 5. 1 3. 0 pine 5 2 10. 3 7. 8 6. 2 5. 5 4. 2 2. 5 lake ! 10. 6 11. 4 10. 6 1 1. 0 11. 3 1 1 . 2 spruce C 1 10. 8 1 1 . 4 11 . 3 11 . 4 11 . 4 10. 6 spruce 1 1 10. 6 11 . 2 10. 8 1 1 . 2 10. 5 9. 6 spruce 3 1 11 . 1 10. 7 9. 9 10. 1 9. 8 9. 2 spruce 5 1 11. 2 10. 6 9. 4 9. 8 9. 6 9. 0 lake 2 9. 7 9. 8 10. 1 9. 3 9. 5 9. 1 spruce C 2 9. 6 9. 8 9. 8 9. 2 9. 5 9. 1 spruce 1 2 9. 6 9. 7 9. 4 8. 7 8. 5 8. 2 spruce 3 2 9. 6 9. 1 8. 0 6. 7 7. 3 6. 0 spruce 5 2 9. 7 8. 8 7. 6 5. 6 5. '3 3. 4 between June and Ju ly experiments or pine and spruce log treatments. The increases in L-T concentrat ion were not l a rge ; the greatest change was from 0.45 to 2.00 mg/l in 25 days for the 5 log spruce treatment. Control enclosures and lake water had s im i l a r and L-T concentrat ion (<0.50 mg/l) over the 25 day experiments. 120 P I N E S P R U C E Q 40- • MAY 26-JUNE 20 I I JUNE 2-JUNE 27 Control • • 1 log • - • 3 logs A -A 5 logs •• « 5 10 15 TIME (days) TIME (days) Figure 7. L ignin- tannin concentrations (mg/l) in experimental enclosures (1985) for log treatments and controls (see legend). K3 28 2 .3 .2 .2 Zooplankton Juveni le copepods were numerical ly dominant in both the lake and the enc losures , followed by Diaptomus s p p . , Diacyclops  thomasi, Daphnia s p p . , and Bosmina coregoni . Th is zooplankton assemblage i s t y p i c a l of Babine Lake (Rankin 1977, Levy et a l . 1984). That i n i t i a l d e n s i t i e s of zooplankton in the enclosures were approximately 30% lower, on average, than in the lake (Figures 8 to 13) does not detract from the v a l i d i t y of the experiments. Lake zooplankton dens i t i es f luc tuate both within and between years over a range which includes l e v e l s measured in the enc losures . The o v e r a l l trends observed for the lake zooplankton (Figures 8 and 9) were the same as observed in the June and Ju ly cont ro l enc losures , which ind icates the s i m i l a r i t y between enclosures and the natura l lake . Perhaps most important, the enclosures were s im i l a r to one another. S i m i l a r i t y in species composition between enclosures was s a t i s f a c t o r y (Table 3); percent s i m i l a r i t y (Renkonen's Index; Wolda 1981) between enclosures ranged from 77% to 97%. S i m i l a r i t y between cont ro l enclosures stocked at d i f f e r e n t times ranged from 55% to 92%. Zooplankton abundance decreased in log enclosures r e l a t i v e to con t ro l enclosures during a l l experiments (Figures 10 to 13; 29 120f 80 \ A nauplii 40+ y 3 3 0 , \ copepodites 20+ A 10+ 0 \ i\ • r±:r^A ••' • v r - ...» MAY 26 JUNE 6 JUNE 16 JUNE 26 JULY 7 JULY 17 JULY 27 AUG 6 DATE Figure 8. Naupl i i and copepodite d e n s i t i e s ( n o . / l ) in the lake (z a 3 m) from May 26-August 3, 1984. 30 4r Diacyclops thomasi 2-1- A A I f fx 111 CD 2 10 8 6-4- • 2 Diaptomus ashlandi X A \ •4-V \ SL 8T 6 Daphnia longiremis 4- -2 -A A i \ / 25T 2 0 Bosmina coregoni 15 10 5 •f-V l 7 v 4-MAY 26 JUNE 6 JUNE 16 JUNE 26 JULY 7 JULY 17 JULY 27 AUG 6 DATE Figure 9. Dens i t ies ( n o . / l ) of niarcyclpps thpmasi, n i a p r n m n S a s h l a n d i , Daphnia longirftmis, and Bosmina r o r p y n n i in the lake (z = 3 m) from May 26-August 3, 1984. 31 Table 3. Percentage s i m i l a r i t y (Renkonen's index) matrix of i n i t i a l zooplankton p o p u l a t i o n s i n 1985 e n c l o s u r e experiments. Tree-d u p l i c a t e 3 l o g 5 l o g c o n t r o l lak< pine-1 1 l o g 95 97 87 92 3 l o g - 96 68 88 5 l o g - - 87 92 c o n t r o l — — - 82 pine-2 1 l o g 89 88 83 70 3 l o g - 93 86 61 5 l o g - - 90 57 c o n t r o l -_ _ 52 spruce-1 1 l o g 94 93 90 91 3 l o g - 96 86 85 5 l o g - - 84 85 c o n t r o l — — — 81 spruce-2 1 l o g 89 90 81 70 3 l o g - 96 77 72 5 l o g - - 78 69 c o n t r o l - - - 77 Table 4 ) . The pine and spruce l o g treatments d i d not s i g n i f i c a n t l y d i f f e r i n t h e i r e f f e c t on zooplankton abundance (p=0.130). However, l o g treatments reduced zooplankton d e n s i t y i n r e l a t i o n to the number of l o g s and t h i s e f f e c t was s i g n i f i c a n t (P=0.041). Comparison among the means f o r l o g treatments r e v e a l e d that the f i v e l o g treatment was 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 t r o l (p=0.007) and that the three l o g treatment approaches s t a t i s t i c a l s i g n i f i c a n c e (p=0.053). There were d i f f e r e n c e s i n the way t h a t zooplankton s p e c i e s Source of var. Sum squares df Mean square F S i g . of Within c e l l s 22.04868 64 0.34451 Tree species 0.81042 1 0.81042 2. 35237 0.130 Log number 3.01298 3 1.00433 2. 91523 0.041 Zoop. species 38.71218 7 5.53031 16. 05266 0.000 Tree*Log 0.41736 3 0.13912 0. 40382 0.751 Tree*Zoop 2.21280 7 0.31611 0. 91758 0.499 Log*Zoop 2.24914 21 0.10710 0. 31088 0.998 Tree*Log*Zoop 1.31333 21 0.06254 0. 18153 1.000 Table 4. Three way MANOVA (with repeated measures) of zooplankton abundance i n l o g t r e a t e d enclosure experiments. CO 33 DATE Figure 10. Zooplankton densi t ies for common species in spruce log treated and control enclosures (June 2-June 27, 1985) (see legend). LC6C80  . CONTROL • 1 LOG >• 3 LOGS •O 5 LOGS 34 DATE Figure 11. Zooplankton densi t ies for common species in spruce log treated and control enclosures (July 9-August 3, 1985) (see legend). _ l CONTROL - • J LOGS - O 5 LOGS f 35 DATE Figure 12. Zooplankton densi t ies for common species in pine log treated and contro l enclosures (May 26-June 20, 1985) (see legend). L E 6 E | I 0 • CONTROL — « 1 LOG 3 LOGS 36 DATE Figure 13. Zooplankton densi t ies for common species in pine log treated and contro l enclosures (July 2-July 27, 1985) (see legend). IEGDIB « COKTDOL « 1 LOG ——• 3 LOGS 5 LOGS 37 0.8 0.6 0.4 % 0-2 > ol TJ C o CO O S a a5 0 6 0.4 02 0 JUNE JULY 0.8 r 10 15 20 25 08 10 15 20 25 o • 5 logs • — • 3 logs ' -Hog • * control 2 m 10 15 20 25 10 15 20 25 Time (days) Figure 14. D i v e r s i t y ind ices (Simpson's D) for log t reated and cont ro l enclosures under a l l treatments (see legend) . 38 and l i f e stages responded to log treatments (P<0.001). Copepod juveni le l i f e stages (naupl i i and copepodites) were more d e l e t e r i o u s l y a f fec ted than adult zooplankton and th is e f f ec t was s t a t i s t i c a l l y s i g n i f i c a n t (P<0.001). The e f fec t of log treatment on the adult zooplankton was not s t a t i s t i c a l l y s i g n i f i c a n t . There were no s i g n i f i c a n t in te rac t ions between any of the main e f f e c t s (Table 4 ) . Simpson's d i v e r s i t y ind ices for log treated enclosures showed no consistent pat tern , compared to c o n t r o l s , for zooplankton populat ions over the course of the 25 day experiments (Figure 14). With a maximum H of 0.90, d i v e r s i t y values ranged between 0.12 and 0.82. 39 2.4 DISCUSSION Based on the water q u a l i t y and zooplankton abundance r e s u l t s obtained from bark addi t ions to enclosures during the 1984 f i e l d season, I was u n s a t i s f i e d with the a p p l i c a b i l i t y of bark treatment resu l ts to the f i e l d s i tua t ion where logs are the treatment f a c t o r . F i r s t l y , the water qua l i t y condi t ions created by bark addi t ions were u n r e a l i s t i c r e l a t i v e to f i e l d measurements, p a r t i c u l a r l y for the 20 kg and 5 kg bark treatments. L-T l e v e l s are < 2 mg/l in the Morrison Arm log storage area during June 1985 (Levy et §_1. 1985b) whereas the lowest bark treatment L-T concentrat ion was 11 mg/l a f te r two weeks. I decided to use log addi t ions for treatments, based on the promising resu l ts (< 5 mg/l) of the eight log treatment. Secondly, in 1984, i n i t i a l zooplankton populat ions were not s u f f i c i e n t l y s imi la r between treatments and cont ro ls to draw conclusions about treatment e f f e c t s . As a r e s u l t , a zooplankton stocking method for enclosures was adopted for the 1985 f i e l d season. However, the q u a l i t a t i v e trends determined for bark treatments (1984) are consis tent with those measured more q u a n t i t a t i v e l y in log treatments (1985). 2.4.J_ Water Qual i ty Log treatments s i g n i f i c a n t l y reduced d isso lved oxygen concentrat ions over the course of the enclosure experiments with oxygen deplet ion increas ing with time and number of l o g s . This 40 resu l t agrees with other water q u a l i t y measurements made by Wentzell ( in prep.) (eg: C .O.D. and T . O . C ) . It i s c lear from the l i t e r a t u r e (Graham 1970, Sproule and Sharpe 1970, Schaumburg 1973) that under s t a t i c c o n d i t i o n s , leachate concentrat ion increases with both time and the r a t i o of wood/water volume r e s u l t i n g in associa ted water q u a l i t y changes, as descr ibed for the enclosure experiments by Wentzell ( in p r e p . ) . There were no c lear d i f fe rences between spruce and pine log treatments in enclosure water q u a l i t y . There were s i g n i f i c a n t d i f fe rences in the d isso lved oxygen resu l ts for June and Ju ly experiments (Wentzel l , in p r e p . ) . During June, for spruce and pine log treatments, d isso lved oxygen l e v e l s were reduced but remained above 75% oxygen sa tura t ion , which would be adequate for f i s h s u r v i v a l . However, during the July experiments, oxygen concentrat ion dropped below 40% oxygen saturat ion ( l e tha l l e v e l s for f i s h ; Davis 1975) for the 3 and 5 log pine treatments and the 5 log spruce treatment. It i s not c lea r why there i s such a marked d i f fe rence in oxygen l e v e l s in the June and Ju ly experiments. Factors which may d i f f e r between the two time periods and contr ibute to d i f fe rences in d isso lved oxygen are temperature, leachate production and b a c t e r i a l biomass, r e s p i r a t i o n and a c t i v i t y . Mean temperatures of 9.4 and 15.3 deg. C for the June and July experiments, r e s p e c t i v e l y , may resu l t in d i f f e ren t leaching ra tes . However, there was no d i f fe rence in l i g n i n and tannin concentrat ion between the two months, which suggests that the 41 oxygen d i f fe rences are not a resu l t of temperature and leachate product ion . Wentzell ( in prep.) supports t h i s conclusion with C.O.D. and T . O . C . data which do not s i g n i f i c a n t l y d i f f e r between the two months. A l s o , l i g n i n s and tannins are large complex compounds which are not e a s i l y broken down (Schaumburg 1973) so i t i s very un l i ke ly that the i r concentrat ion in Ju ly i s low due to degradat ion. There i s s t i l l a p o s s i b i l i t y that the water soluble ext racts from logs cut at the two d i f f e r e n t times were responsible for d i f fe rences in oxygen dep le t ion . The chemistry of wood leachates i s extremely complex and there may be seasonal changes in the chemical const i tuents and the i r concentrat ions which were undetectable by the various measurements made by Wentzell ( in p r e p . ) . For example, wood sugars may be rapid ly degradable By microbes with a high "turnover", r e s u l t i n g in l i t t l e cont r ibut ion to T .O .D . and C.O.D. despi te high microbia l a c t i v i t y (Wentzel l , in p r e p . ) . The most l i k e l y explanation for the d i f fe rences in d i s s o l v e d oxygen between June and Ju ly experiments is oxygen deplet ion as a resu l t of temporally varying chemical and b i o l o g i c a l oxygen demands. Work by Wentzell ( in prep.) on the C .O.D. of log leachate found no d i f ference between the two months. B i o l o g i c a l oxygen demand, although not d i r e c t l y measured, i s re la ted to b a c t e r i a l number and a c t i v i t y which was determined over the course of a l l enclosure experiments (Wentzell in p r e p . ) . Based on the oxygen measurements, I would expect b a c t e r i a l a c t i v i t y rate and/or numbers to have been 42 higher in J u l y . This was not found to be the case; b a c t e r i a l number and a c t i v i t y rates in Ju ly were s imi la r to those in June (Power and Wentzell 1985, Wentzell in p r e p . ) , however, b a c t e r i a l biomass was s i g n i f i c a n t l y lower in J u l y . H a l l et a l . ( in prep) suggest that the smaller b a c t e r i a l biomass in Ju ly had a better a b i l i t y to take up substrate due to a higher metabolic a c t i v i t y per organism, r e s u l t i n g in lower d isso lved oxygen concentra t ion . This hypothesis is supported by the i r b a c t e r i a l uptake k ine t ic data . The log treatment enclosure experiments demonstrate that water q u a l i t y i s extremely s e n s i t i v e to log loading d e n s i t i e s . The r e s u l t i n g water q u a l i t y changes can produce condi t ions which are l e t h a l for f i s h and many inver tebra tes . A major problem in most laboratory experiments which examine wood leachates and water q u a l i t y i s that loading dens i t i es are orders of magnitude higher than in f i e l d s i t u a t i o n s and produce u n r e a l i s t i c water q u a l i t y l e v e l s . For example, Graham (1970) and Atkinson (1971) submerged logs in 50 1 aquar ia , producing waters with a C.O.D. as high as 600 m g / l . The maximum f i e l d measurement of C .O.D. in the Houston Forest Products log storage s i t e was 50 mg/l (Levy et a l . 1985b). The maximum C.O.D. for the enclosure experiments was 70 mg/l in the 5 log treatments (Power and Wentzel l , 1985). In the enclosure experiments, l i g n i n and tannin concentrat ions are s i m i l a r to concentrat ions measured in the log storage s i t e (Levy et a l . 1985b). Agreement between experimental enclosure and f i e l d r e s u l t s i s s t r i k i n g ; s t a t i c condi t ions in the log boom 43 resu l t in water qua l i t y s imi la r to that measured in enclosure experiments. The log loading density for the Morrison Arm log storage s i t e , as ca lcu la ted in Chapter 3, i s 0.33 cubic meters/cubic meter water, which i s higher by an order of magnitude than the highest log loading densi ty (0.0335 cubic meters wood/cubic meter water) used in enclosure experiments. Al lowing for water c i r c u l a t i o n in the log storage area, the use of enclosures proved to be an e f f e c t i v e way to experimentally simulate log storage condi t ions and examine the i r e f f ec ts on water q u a l i t y . It fol lows that the b i o t i c component of the enclosures w i l l be under p h y s i c a l and chemical condi t ions s im i l a r to those which occur in the f i e l d as w i l l be examined in the General D i s c u s s i o n . 2.4.2 Zooplankton Laboratory tes ts have shown that log leachates are acutely toxic to severa l aquatic organisms such as salmon eggs and f ry (Serv i z i et a l . 1971, Pease 1974, Peters et a l . 1976) and c a d d i s f l y larvae and mayfly nymphs (Peters et a_l. 1976), but t o x i c i t y to zooplankton has never been examined. The enclosure experiments were conducted at low, r e a l i s t i c log loadings with the p o s s i b i l i t y of measuring responses at the community l e v e l . Log leachates reduced zooplankton density in a l l treatments over time, with 5 log experiment populat ions being most severely a f f e c t e d . Th is pattern i s l inked to water q u a l i t y , as zooplankton respond to changes such as reduced d isso lved oxygen 44 and increases in leachate concentra t ion . Sprague (1970) emphasizes that environmental condi t ions ( in t h i s case d isso lved oxygen) may great ly modify t o x i c i t y and discusses several examples from the l i t e r a t u r e . Wentzell ( in prep.) monitored ch lo rophy l l a in enclosures and found that oxygen deplet ion and leachates generated by logs d id not adversely a f fec t a l g a l standing c rops . The algae consumed by zooplankton would have to be monitored to test the hypothesis that zooplankton numbers were reduced through food l i m i t a t i o n . No s i g n i f i c a n t d i f f e rence in zooplankton response to pine and spruce log treatments was found. This i s reasonable given that there were no measured d i f fe rences in water qua l i t y between treatments. D i f ferences in t o x i c i t y between other tree species have been shown by severa l researchers (Atkinson 1971, Buchanan et a l . 1976) but for higher leachate concentrat ions than occur in most log handling f a c i l i t i e s . These studies obtained tox ic leachates through ex t rac t ion processes which involve high loading d e n s i t i e s and gr inding of wood chips in water. Whole log experiments produce more d i l u t e leachates which are not usual ly measurably tox ic to salmonids (Atkinson 1971, Schaumburg 1973, Pease 1974). In enclosure experiments, only reductions in abundance of juveni le ca lanoid and cyc lopo id copepods (naupl i i and copepodites) were s t a t i s t i c a l l y s i g n i f i c a n t . Ear ly l i f e h is tory stages tend to be the most suscept ib le to tox ic substances for 45 both f i s h and invertebrates (APHA et a l . 1985, McKim 1985). P o t e n t i a l l y , for young sockeye salmon feeding in the log storage area at Morrison Arm, there may be a reduction in l o c a l food l e v e l s since f ry feed mainly on copepodites (Levy et a l . 1984). Negative e f f e c t s of wood leachate on zooplankton were determined at r e a l i s t i c leachate concentra t ions . At the community l e v e l , d i f fe rences in species d i v e r s i t y between log treated and cont ro l enclosures was p red ic ted , based on the premise that community s t ructure would change as a resu l t of log storage. According to Washington (1984), s t resses appl ied to a community as a resu l t of p o l l u t i o n should be r e f l e c t e d in changes to the community s t ruc tu re , of which species d i v e r s i t y may be an i n d i c a t o r . Species d i v e r s i t y has been used in a few other studies to evaluate the impact of a toxicant upon a zooplankton community. For example, Kaushik et a l . 1985, documented reductions in species d i v e r s i t y of zooplankton in response to app l i ca t ion of permethrin (an i n s e c t i c i d e ) to enc losures . The changes in species d i v e r s i t y which occurred in zooplankton communities in log enclosures showed no consistent pat tern , which could be due to a number of reasons. If species d i v e r s i t y i s a measure of community s t ruc ture , than th is resu l t suggests a lack of e f f ec t of log leachate at the zooplankton community l e v e l ; however, there are severa l a l t e rna t ive hypotheses. D i v e r s i t y indices may not be a good or sens i t i ve 46 measure of community s t ruc ture . A l s o , responses by each zooplankton taxa may have been equal , r e s u l t i n g in no net change in r e l a t i v e abundance, upon which d i v e r s i t y i s based. There is l im i ted scope for determining s i g n i f i c a n t changes in d i v e r s i t y because species r ichness in Babine Lake is low and small changes may not be detected by a d i v e r s i t y index. S imi lar r e s u l t s at the community l e v e l using s i m i l a r i t y ind ices were obtained for zooplankton in selenium enclosure experiments (Salk i et a_l. 1985) where no acute or chronic e f f e c t s were measured, despite ind ica t ions from laboratory bioassays that selenium was toxic to zooplankton. 47 3. FIELD STUDY 3.1 INTRODUCTION U t i l i z a t i o n of the l i t t o r a l zone by sockeye f ry during the i r f i r s t few weeks of l i f e has been widely observed (McDonald 1969, Levy et al_. 1984) and t h i s would seem to be the zone most severely a f fec ted by log storage on Babine Lake. Impacts such as bark accumulation, sediment compaction, reduction in benthic prey organisms and reduced water q u a l i t y are described for log storage areas (Pease 1974, Conlan and E l l i s 1979, Toews and Brownlee 1981). However, there are few studies which experimental ly examine the d i r e c t e f f ec ts of log storage on f i s h (Sedel l and Duval 1985). This i s par t l y due to the l o g i s t i c a l problems associa ted with car ry ing out research in log storage areas , where, for example, submerged logs and debr is make many f i s h capture methods i m p r a c t i c a l . Given that sockeye f ry u t i l i z e l i t t o r a l habitat (McDonald 1969) for the i r f i r s t few weeks of the i r lake res idence, there is concern that log handling a c t i v i t i e s during that per iod may detr imenta l ly a f f e c t these juveni le salmon. Sockeye f ry leaving Morrison River enter Babine Lake only 1 km from the Houston Forest Products dump s i t e (Figure 15). Morrison Arm i s e s s e n t i a l l y a migration c o r r i d o r , along which f ry must t rave l from the Morrison River to the main body of Babine Lake. Levy et a l . (1985b) have examined r e l a t i v e u t i l i z a t i o n of the l i t t o r a l 48 Figure 15. Map of Morrison Arm, Babine Lake, B .C . Locat ions of f ry feeding experiments are marked and descr ibed in the legend. As i n d i c a t e d , see Figure 16 for a map of the log dump bay. 49 zone along Morrison Arm and determined that the highest numbers of sockeye f ry were onshore at the head of the arm. They l i k e l y s h i f t in to the pelagic zone as they migrate towards the main basin of Babine Lake. Deter iora t ion of water q u a l i t y or habitat caused by log storage may i n h i b i t or change migration of inshore sockeye f ry within the arm. If log booms a f fec t the zooplankton community in areas where sockeye f ry feed, the d ie t of f ry could be a l t e r e d . Dietary change may detr imenta l ly a f f e c t the i r growth and s u r v i v a l during the i r f i r s t few weeks of l i f e . To look at these concerns, t h i s f i e l d study examines (1) water residence time and water qua l i t y in log boom and cont ro l s i t e s , (2) di f fe rences in food supply and d ie t for sockeye f ry held in enclosures in log storage and cont ro l s i t e s . 2.1-1 Water residence and water q u a l i t y The forest industry had acquired approximately 950 coasta l leases and reserves by 1983 (Edgel l and Ross 1983), 64% of which were used for log storage a lone. These leases have the common c h a r a c t e r i s t i c of being shel tered from wind, waves and cur rents . Houston Forest Products' log storage s i t e at Morrison Arm, Babine Lake i s no except ion; t h i s s i t e i s in the most protected bay (Figure 15) within the region meeting the c r i t e r i a for a log dump s i t e . In a d d i t i o n , the presence of log booms decreases lake surface area per uni t volume water, consequently further reducing the po ten t ia l for mixing of the water column by wind a c t i o n . 50 Obviously , l e t h a l l eve ls of oxygen (< 4 mg/l for salmonids) are l i m i t i n g to f i s h (Davis 1975). C r i t i c a l oxygen l e v e l s can a lso be def ined as those which cause sublethal e f f ec ts such as loss of equ i l ib r ium and resp i ra t ion s t ress (Davis 1975). For young sockeye salmon Brett (1964) determined that reduced l e v e l s of oxygen detr imenta l ly a f fec ted swimming performance which may reduce the a b i l i t y of f ry to capture prey. Invertebrates may a lso respond negat ively to low oxygen l e v e l s , although they usual ly have higher tolerance l e v e l s than f i s h (Davis 1975). Res t r ic ted f lush ing has been l inked to de te r io ra t ion of water qua l i t y (Pease 1974), p a r t i c u l a r l y depleted oxygen c o n d i t i o n s , which are caused by high B.O.D. ( b i o l o g i c a l oxygen demand) and C.O.D. (chemical oxygen demand) as demonstrated in many laboratory studies (Graham 1970, Sproule and Sharpe 1970, Atkinson 1971, Toews and Brownlee 1981). Water q u a l i t y has been c l o s e l y monitored in log storage s i t e s (Levy et a l . 1984, 1985a, 1985b) on Babine Lake and in the present study during 1985 within the Morrison Arm log handling s i t e . During the 1984 f i e l d season, depleted oxygen condi t ions were not observed in the Morrison Arm log handling area (Levy et a l . 1985a). Several studies (Schaumburg 1973, Pease 1974, Duval and Slaney 1980) conclude that water f low, in the majority of cases , i s enough to prevent e i ther accumulation of toxic leachates or any reduction in oxygen which could adversely a f fec t f i s h . Duval and Slaney (1980) could f i n d no record of t h i s kind of severe oxygen deplet ion in B r i t i s h Columbia. Based on resu l ts of the 1984 f i e l d season and laboratory work, i t was c lear that leachates from tree species harvested in the Babine Lake watershed could exert a s i g n i f i c a n t oxygen demand. Since oxygen deplet ion d id not occur in the Morrison Arm log handling area in 1984, I hypothesized that water movement within the boom was enough to d i l u t e the chemical e f f e c t s of log storage. Water movement and residence time can be examined by introducing a dye into the water and t rack ing i t s movement over time ( K i s i e l et a l . 1964). Therefore, I examined water residence time and water qua l i t y in the log storage area of Morrison Arm, to determine the r e l a t i o n s h i p between water exchange and oxygen c o n d i t i o n s . 3_.j_.2_ Food supply and d ie t of sockeye f ry The qua l i t y and quant i ty of food ava i l ab le to juveni le f i shes i s accepted as being an important factor in the i r growth and s u r v i v a l (Braum 1967), as has been demonstrated in several s tudies (Hjort 1914, LeBrasseur 1969, Eggers 1978). A c r i t i c a l per iod for f i s h larvae seems to occur when they s h i f t from yolk sac to external feeding; at t h i s time a food shortage may make them p a r t i c u l a r l y vulnerable to predation and adverse environmental c o n d i t i o n s . A large proport ion (50%) of the sockeye c o l l e c t e d in Morrison Arm had remnants of a yolk sac 52 (pers. o b s . ) . For juven i le sockeye salmon, ra t ion l e v e l and growth rate are l inked (Brett et a l . 1969, Bret t and Shelbourn 1975). In the Babine-Ni lki tkwa lake system, the mean growth rate of pe lagic sockeye salmon f ry increases assymptot ica l ly with the mean zooplankton biomass (Johnson 1961) and I would expect the same r e l a t i o n s h i p in younger, l i t t o r a l sockeye. Fry to smolt mor ta l i ty processes for Babine Lake sockeye have been studied by West (1983), who found high morta l i ty rates among f i s h of smaller body s ize at emergence. It appears that these f ry take longer to grow out of the s i ze window in which morta l i ty i s the most in tense. Sockeye f ry - to -smol t morta l i ty rates have been shown to decrease with increased length of lake residency (Foerester 1938). In the present study, d i f fe rences in food supply and d ie t of sockeye f ry in log storage areas v s . undisturbed lake habitat are examined. If log storage detr imenta l ly a f f e c t s sockeye salmon feeding, I predicted that a change in food supply (quantity and/or qua l i ty ) and d ie t would be ev ident . A decrease in the amount of food ava i l ab le or ingested by juveni le salmon held in enclosures in log storage areas could be accepted as evidence of a d i r e c t negative impact of log handling a c t i v i t i e s . 53 3.2 METHODS Water residence and water q u a l i t y A t r i a l dye (rhodamine-B) study was conducted on May 28, 1985 in the open water near the log dump ramp. The stock so lu t ion concentrat ion of rhodamine-B used in experiments was chosen to be 1 g / 1 . At th is i n i t i a l concentra t ion , d i l u t i o n s of up to 15,000 times were s t i l l v i s i b l e . A cont ro l experiment (June 3, 1986) was conducted in open water within the log boom s i t e to observe water movement in water without log bundles. The rate of movement was observed from shore. Within the log booms located c loses t to the log dump s i t e , a sampling g r i d was l a i d out to cover an area 100 m by 100 m. Ten l i t r e s of rhodamine-B dye (1 g/1) were introduced (Figure 16) in an instantaneous dose to track water movement. The ob ject ives were to sample over time the locat ion and dye concentrat ion of (1) the centre of the dye cloud (2) the perimeter of the dye cloud and (3) the depth of the centre of the dye c l o u d . Samples were taken by hand at the surface or by a Par diaphragm pump and hose, at depths below the sur face . Sampling began immediately fo l lowing the dye in t roduct ion and continued 54 30m Figure 16. Sketch map of the H . F . P . log dump bay and storage area showing booms and log ramp (see Figure 15 for loca t ion in Morrison Arm). Water q u a l i t y and in s i t u bioassay s i t e s are marked with a t r i ang le and l e t t e r ( top) . The dye study s i t e i s i l l u s t r a t e d showing log bundle arrangement and release point for dye (below). 55 at 5 minute in te rva ls for 0.5 h, then 10 minute in te rva ls for 1.5 h at the centre and perimeter of the dye c l o u d . Water samples at depths of 0, 0.25, 0.50, 1.0, 2 .0 , 3 .0, 4.0 and 5.0 m were taken at 0.5 h in te rva ls for 3.5 h fo l lowing int roduct ion of the dye. The movement of the cloud was tracked on the g r i d map at 5 minute i n t e r v a l s . Due to the slow movement of the dye c loud , the g r i d s ize was reduced to 30 m by 20 m. The loca t ion and log bundle layout of the gr id in the log storage s i t e i s marked in Figure 16. Water qua l i t y (temperature, oxygen) measurements were taken at s i t e s along a transect (Figure 16) and at a cont ro l s i t e . S i tes A and E are in "open" water within the log storage inner bay. S i tes B, C, and D are within the log boom and the cont ro l s i t e i s in 5 m of open water near the 2.0 m reference s i t e used in the fry feeding experiment (Figure 15). In s i t u bioassays were conducted at water q u a l i t y s i t e s (Figure 16). Ten sockeye f ry held at each s i t e in flow through enclosures were monitored for resp i ra tory s t ress and morta l i ty on June 3, 1985. Water samples were analyzed for dye concentrat ion by v i s u a l comparison with known concentrat ions of rhodamine-B in a method adapted from Standard Methods (APHA et a l . 1985). Two 50 ml matched Hel ige Aquatester tubes were f i l l e d to the 50 ml mark, one with the sample, the other with appropriate standard. By looking v e r t i c a l l y downward through the tubes toward a l igh ted white sur face , standard comparisons were made. D i l u t i o n s by 10% increments of 1 g/1 rhodamine-b down to 1/15000 (+ 10%) were d i s c e r n i b l e by t h i s method. The surface area of the boom and the head of Morrison Arm were determined using software ("lake morphometry") on an Apple computer with a graphics t a b l e t . The volume of water below the log boom was a lso determined. 3.2.2 Food supply and d ie t of sockeye f ry Feeding studies were conducted in s i t u at Morrison Arm, Babine Lake, B r i t i s h Columbia in la te May and ear ly June, 1985. The fol lowing s i t e s were se lected to compare d i e t s of sockeye fry in log handling areas (treatment) and undisturbed l i t t o r a l habitat ( reference) : (1) log boom treatment s i t e (2 m) (2) undisturbed reference s i t e (2m) (3) log dump treatment s i t e (0.5 m) ( 4 ) undisturbed reference s i t e (0.5 m) The locat ions of these four s i t e s are shown in Figure 15. The d isso lved oxygen concentrat ions at a l l s i t e s were above 6.0 m g / l . Th is study design does not provide r e p l i c a t i o n of treatments; a greater number of s i t e s in each area are required 57 to s t a t i s t i c a l l y test for d i f fe rences between treatments (Hurlbert 1984). The log boom and log dump s i t e s represent habi tats exposed to two kinds of log handling a c t i v i t i e s which sockeye f ry might encounter. The shallow log dump s i t e i s used regu lar ly over the winter and has higher rates of bark deposi t ion than the log boom area which i s r e l a t i v e l y undisturbed once covered with log bundles (Levy et a l . 1985b). Reference s i t e s in waters of appropriate depth were se lected in areas of s im i l a r undisturbed substrate and exposure to the two treatment s i t e s . During the feeding experiments, f ry were held in flow-through enclosures (FTEs) which permitted ample water c i r c u l a t i o n and zooplankton replenishment. Sampling indicated that there was no s i g n i f i c a n t d i f fe rence in zooplankton abundance or species composition in samples taken within or outside the enc losures . Each FTE consis ted of green vexar p l a s t i c mesh (3 mm mesh s ize) stretched and fastened over a l l s ides of a 0.5 X 0.5 X 0.5 m aluminium frame box (Figure 17). One side had a removable s l i d i n g door to allow access into the otherwise completely enclosed box. On the top of the FTEs were four aluminium loops from which the cages could be suspended in the water column. Six FTEs were const ructed , two of which were modif ied for zooplankton sampling. The add i t ion of a small hole and mesh cover f l a p allowed inser t ion of the zooplankton pump hose into the top of the FTE. Figure 17. Design of flow through enclosures used in f ry feeding experiments. 5 9 Sockeye f ry used at the log boom and 2 m reference s i t e s were obtained by beach se in ing from Morrison Arm, Babine Lake. The f ry used at the log dump and 0.5 m reference s i t e s were c o l l e c t e d at Ful ton River spawning channel , due to the low abundance of f ry in Morrison Arm in ear ly June. The average length (mean + standard deviat ion) of f ry used in the experiments was 2.8 + 0.1 cm. There was no s i g n i f i c a n t d i f fe rence in length of f ry used for each set of experiments. The log boom experiments were conducted on May 22-23 and May 28-29, 1985 and the log dump experiment was conducted on June 4 -5 , 1985. It was not poss ib le to t rave l to or stay at Morrison Arm on any other dates; t h i s r e s t r i c t e d the number of experiments which were conducted. The afternoon before the s tar t of an experiment, three FTEs were i n s t a l l e d at each s i t e (two for f i s h , one for zooplankton sampling). For the log boom and 2 m s i t e s , each FTE was independently suspended at 0.25 m depth from a boom and f loa t r e s p e c t i v e l y . For log dump and 0.5 m reference s i t e s , the FTEs were placed on the sediment at a depth which just completely immersed the top of the cage. A t o t a l of 200 f ry were randomly d iv ided into groups of 50 and each group was introduced into a FTE the afternoon before the s ta r t of an experiment. It was observed that young sockeye f ry c lea r the i r stomach contents overnight , so stomach samples taken the fol lowing day contain prey captured only in the 60 enclosures. In t r i a l feeding experiments i t was determined that there was no s i g n i f i c a n t d i f fe rence in net food intake per fry when f ry were held at d e n s i t i e s of 10 or 50 fry per enclosure . Sampling began before dawn and continued through u n t i l the morning of the fo l lowing day. The sampling regime cons is ted of both f ry and zooplankton samples being taken at each s i t e at regular (usual ly 4 h in terva ls ) throughout the experiment. Zooplankton samples were taken with a Par diaphragm pump f i l t e r e d through a 100 micrometer mesh net and preserved in a sucrose-5% formalin mixture (Haney and Ha l l 1975). Dupl icate two minute samples were taken from f i s h l e s s FTE each sample time. F i s h were sampled by d ipnet t ing 5 f ry from each enclosure at each sample t ime, and these were preserved in 10% formal in . Travel between the treatment and reference s i t e s was timed to keep sample c o l l e c t i o n times as s imi la r as poss ib le for the two s i t e s . Zooplankton samples were examined in toto or by s p l i t t i n g into 1/5 subsamples. Rare species were counted from the to ta l sample. Samples were ennumerated and i d e n t i f i e d under a stereo d i s s e c t i n g scope using Edmondson (1959) and Smith and Fernando (1978) for taxonomic c l a s s i f i c a t i o n . Fork lengths were recorded for each f i s h and stomach contents were analyzed under a stereo d i s s e c t i n g scope. Stomachs were d issected out of preserved f i s h specimens by making 61 i n c i s i o n s at the esophagus and at the junct ion of the p y l o r i c sphincter with the i n t e s t i n e . Absence or presence of the yolk sac was noted. The stomach f u l l n e s s was estimated on a scale of 0 (empty) to 10 ( f u l l ) (Hyslop 1980). The stomach contents were spread out in a p e t r i d ish in a drop of water and food items were i d e n t i f i e d , sorted and ennumerated. V i s u a l estimates (+5%) of the r e l a t i v e volume of each prey type were made. Overa l l assessments of the state of stomach contents were made (eg: f r e s h , d iges ted) . Fresh zooplankton were in tact and loose in the gut, whereas digested zooplankton were almost u n i d e n t i f i a b l e . Prey were categor ized as fo l lows: Diacyclops Diaptomus Daphnia Bosmina naup l i i / copepodi tes (calanoids and cyc lopoids) chironomid larvae insect pupae insect adul ts u n i d e n t i f i a b l e (digested matter) The numerical r e l a t i v e proport ions of each food item in the guts were ca lcu la ted for each sample time. Proport ion data were transformed by square root arc s i n , before means were c a l c u l a t e d , to meet the assumption of normal d i s t r i b u t i o n of the proport ion data (Schef ler 1980). Un iden t i f i ed food items were not inc luded. Prey which were rare ly taken (adult Diaptomus 62 spp., Daphnia, and i n s e c t s were grouped i n t o a category c a l l e d o t h e r . The d i v e r s i t y i n d i c e s can serve as a measure of f e e d i n g h a b i t s f o r comparisons between f i s h (Hyslop 1980). The d i v e r s i t y of prey a c q u i r e d by sockeye f r y was determined f o r each sample time u s i n g Simpsons's D i v e r s i t y Index as recommended by Washington (1984). SIMPSON'S D I V E R S I T Y INDEX ( D ) s 'D - 1 - ( P i ) 2 i=0 where s = no. of species p^ = p r o p o r t i o n of t o t a l no. of i n d i v i d u a l s of i * * 1 species 3.3 RESULTS 3.3.J_ Water re s i d e n c e and water q u a l i t y Two dye r e l e a s e t r i a l s i n open water a t the head of the l o g storage area i n d i c a t e d t h a t the dye c l o u d moved a t r a t e s ranging from 15 to 30 metres per hour, when u n r e s t r i c t e d by l o g bundles. Sur f a c e waters were r i p p l e d by a l i g h t breeze d u r i n g both t r i a l s . F o l l o w i n g an hour of o b s e r v a t i o n , the dye c l o u d s i n open water were d i l u t e d beyond d e t e c t i o n l i m i t s . In c o n t r a s t , the perimeter of the s u r f a c e of the dye c l o u d r e l e a s e d w i t h i n the l o g boom i n i t i a l l y moved a t a r a t e of 20 63 metres/h, and then was v i r t u a l l y stagnant, remaining for at least 8 h. The perimeter d id not expand more than 10 m in any d i r e c t i o n for the rest of the day (Figure 18). The centre of the dye cloud was d i l u t e d as i t spread out . Two minutes a f te r int roduct ion i t was d i l u t e d 20 times and a f te r 7 minutes, 200 t imes. The perimeter d i l u t i o n was 1000 times a f te r 7 minutes, and increased to 15000 t imes, a f ter 3.5 h. At t h i s t ime, the "centre" of the dye cloud was d i l u t e d 3000 t imes, r e l a t i v e to s t a r t i n g condi t ions and was la rge ly r e s t r i c t e d to the top 0.5 m of the water within the log boom area (Figure 19). This phenomenon, in combination with the small l a t e r a l movement of the dye, resu l ted in the dye cloud being contained within an area approximately 15 X 10 m (between 4 log bundles) to a depth of 0.5 m. This d i s t r i b u t i o n implied reduced water movement, l a t e r a l l y or v e r t i c a l l y , within the log boom area . The dye pers is ted u n t i l n i g h t f a l l , but was undetectable the fo l lowing morning. However, the th ick b a c t e r i a l growth which covered the log bundles was heavi ly s ta ined , but only within the upper 0.25 m of water. Extreme oxygen deplet ion (<2.0 mg/l) and elevated temperatures (17.0-18.5 deg. C) occurred in the upper 0.5 m of water in the log boom on June 3, 1986, while "open" areas had only s l i g h t l y depressed oxygen l e v e l s in surface waters (Table 5) . Control s i t e water was cooler (<14 deg. C) and oxygen leve ls were above 9.0 mg/l at every depth. 64 Figure 18. Dye cloud movement in surface waters of a 30 X 20 m gr id within log bundles over a 3.5h per iod on June 3, 1985 (dye re lease loca t ion ind icated by arrow). DILUTION (log) 1:1000 1:100 I I-0_ LU O 5-L 0.25h 5-L 1.5h 5-L 0.50h O F 5-L 1:10000 1:1000 -i 2.0h 1:10000 0 l'.l.'.'.-.'.'.l.t.|l;.ll'T^ 5-L 1.0h 1:10000 1:1000 5-L 3.5h Figure 19. Depth d i s t r i b u t i o n and d i l u t i o n at center of c loud over a 3.5h per iod on June 3, 1985. Depth Si te A S i te B Site ( C Si te ! D S i t e E Reference (m) T DO T DO T DO T DO T DO T DO 0 16.0 7.0 18.0 1.2 18.5 0.8 18.0 1.0 17.0 7.8 14.0 9.2 0.25 15.0 7.0 18.0 1.5 18.0 1.0 18.0 0.9 16.0 7.7 13.0 9.2 0.50 15.0 7.2 17.5 2.0 16.0 1.5 16.0 1.5 16.0 7.7 12.0 9.4 1.0 15.0 9.1 15.0 4.9 15.0 3.8 16.0 2.5 16.0 8.9 10.0 9.9 2.0 12.0 8.7 11 .5 7.2 11.5 8.0 11.0 8.0 12.0 8.2 10.0 9.9 3.0 12.0 8.6 11.5 9.1 11.0 7.9 11.0 8.2 - - 9.0 9.8 4.0 - - 9.0 9.1 9.5 8.8 9.5 8.5 - - 9.0 9.6 5.0 - - 9.0 8.8 9.0 8.2 9.0 9.7 - - 9.5 9.2 Table 5. Water qua l i ty (temperature (deg. C) and d isso lved oxygen (mg/l)) in Morrison Arm on June 3, 1985. See Figure 16 for locat ions of s i tes . (T= temperature, DO= d isso lved oxygen) 67 The surface area of the log boom comprises 15% of the area of the head of Morrison Arm (Figure 15) i s descr ibed by the r a t i o of boom:arm which is 0.15. Given that there were 165,000 cubic meters of logs in the Morrison Arm storage area (P. Ogawa, pers . comm.), and assuming that 50% of each bundle was submerged, the instantaneous woodtwater density can be c a l c u l a t e d . The volume of water below the log boom to a depth of 2 m (thermocline) was 248,000 cubic meters, therefore the woodtwater r a t i o under s t a t i c condi t ions was 0.33 cubic meters wood/cubic meter water. A l l sockeye f ry held at in s i t u l e t h a l bioassay test s i t e s within the log boom (s i tes B, C, and D) were dead within 15 minutes. They exhib i ted signs of extreme resp i ra tory s t ress such as g i l l f l a r i n g , d isor ien ted swimming and surface swimming. Of the ten f ry held at s i t e A, two died and the surv ivors d isplayed infrequent g i l l f l a r i n g . A l l f ry in s i t e E and the reference s i t e survived the 24 h test p e r i o d . 3.3.2 Food supply and d ie t of sockeye fry 3_.3.2_.J_ Zooplankton abundance Over the 24 h experiments there were c l e a r d i f fe rences in zooplankton abundance between reference and boom s i t e s (Figures 20 and 21). Copepodites and naup l i i numerical ly dominated the zooplankton community at a l l s i t e s in a l l experiments. 68 Diacyclops thomasi was the second most abundant zooplankton, followed in decreasing abundance by Bosmina coreqoni , chironomid la rvae , Daphnia s p p . , and Diaptomus spp. In the log boom experiments (May 22-23 and - May 28-29), there were d i f fe rences in l o c a l zooplankton abundance between the log boom and reference s i t e s . Naupl i i were 50% to 200% more abundant at reference s i t e s than at the log boom s i t e s on both dates (Figure 20), with peaks between 1100-1200 h. Copepodites, the most important food item for young sockeye f r y , were more abundant at the reference s i t e on May 22-23, but there was no d i f fe rence on May 28-29 between reference and boom s i t e s (Figure 20). Diacyclops thomasi was present in s imi la r dens i t i es at both reference and boom s i t e s on both dates , except for higher d e n s i t i e s at the reference s i t e near 1200 h, p a r t i c u l a r l y on May 28-29 (Figure 20). The same trend was evident for Bosmina (Figure 20); t h i s species occurred at s im i l a r l o c a l abundancies at reference and boom s i t e s , on both dates. Chironomid larvae were present at very low d e n s i t i e s (<1 ind iv /1 ) almost exc lus ive ly at the reference s i t e in the morning and evening on both experiment dates (Figure 20). Data for Daphnia and Diaptomus are not reported here because of high sampling variances associated with low d e n s i t i e s of these spec ies , and the i r absence in stomach samples. In the log ramp experiment (June 4 - 5 ) , there were s i g n i f i c a n t d i f fe rences in zooplankton abundance between the 69 04 06 12 16 20 24 04 06 c o c IS Q. o o N 33 0) 12J9 WO 60 6J0 4J) 2J0 0 4J0 30 2JD to 0 copepodites 04 06 12 16 20 24 04 06 Bosmina coregoni Diacyclops thomasi 04 06 12 16 20 24 04 06 0 4 0 6 12 1 6 2 0 2 4 0 4 0 6 04 06 12 16 20 24 04 06 Time(h) F i g u r e 20. Zooplankton abundance (no/1 + S.E. f o r subsamples) i n flow through e n c l o s u r e s a t boom and c o n t r o l s i t e s d u r i n g sockeye f e e d i n g experiments May 22-23 and May 28-29, 1985 (dashed l i n e s = c o n t r o l s i t e s , s o l i d l i n e = boom s i t e ; see n a u p l i i graph (top) f o r l a y o u t of May 22-23 and May 28-29). 70 r e f e r e n c e and l o g ramp s i t e s . The d e n s i t i e s of n a u p l i i and copepodites ( F i g u r e 21) were lower at the r e f e r e n c e s i t e than the ramp s i t e d u r i n g the morning and evening. However, n a u p l i i and copepodite abundance at the r e f e r e n c e s i t e c l e a r l y i n c r e a s e s above that of the ramp s i t e d u r i n g the middle of the day. D i a c y c l o p s thomasi and Bosmina coreqoni ( F i g u r e 21) d i d not d i f f e r between r e f e r e n c e and l o g ramp s i t e s . Chironomid l a r v a e ( F i g u r e 21) showed a l a r g e peak i n abundance d u r i n g the 0830 sample at the r e f e r e n c e s i t e with very low abundance d u r i n g a l l other sample p e r i o d s a t both s i t e s . 3.2.2.2 Stomach Contents G e n e r a l l y , the major prey items present i n the f r y stomachs were cop e p o d i t e s , with r e s p e c t to both number and volume. Bosmina coreqoni were taken at a lower frequency, and n a u p l i i , a d u l t copepods Daphnia and i n s e c t s were taken r a r e l y , with the e x c e p t i o n of chironomid l a r v a e . Chironomid l a r v a e were taken i n l a r g e numbers at s i t e s where they were a v a i l a b l e . D i g e s t i v e s t a t u s of gut c o n t e n t s over the course of 24 h experiments showed a s i m i l a r t r e n d i n each case. In g e n e r a l , the morning and a f t e r n o o n gut samples were composed of " f r e s h " zooplankton; evening gut samples were r e l a t i v e l y w e l l d i g e s t e d . Sockeye salmon f r y i n the 2.0 to 3.0 cm s i z e c l a s s completely c l e a r t h e i r stomachs o v e r n i g h t . Time (h) F i g u r e 21. Zooplankton abundance (no/1 + S.E. f o r subsamples) i n flow through e n c l o s u r e s a t ramp and c o n t r o l s i t e s d u r i n g sockeye f e e d i n g experiments June 4-5, 1985 (dashed l i n e s = c o n t r o l s i t e s , s o l i d l i n e s = ramp s i t e ) . 72 Information on ingested food q u a n t i t y was obtained by (1) e s t i m a t i n g stomach f u l l n e s s and (2) c a l c u l a t i n g mean number of each prey item per stomach. For f r y i n FTEs i n both the l o g boom and 2.0 m reference s i t e s (May 22-23 and May 28-29), stomach f u l l n e s s and mean prey/stomach (Figure 22) show s i m i l a r changes over the 24 h experiments, although hourly patterns are not the same f o r the two dates. Food intake begins i n the e a r l y morning w i t h stomach f u l l n e s s peaking between 1200 and 1600 h. Stomach f u l l n e s s and mean prey/stomach then decrease u n t i l the f o l l o w i n g morning. Fry i n FTEs i n the l o g dump and 0.5m reference s i t e s (June 4-5) do not e x h i b i t s i m i l a r trends i n stomach f u l l n e s s or i n mean prey abundance per stomach (Figure 22) over the 24 h p e r i o d . Fry i n FTEs at the 0.5 m reference s i t e e x h i b i t a mid-day peak i n stomach f u l l n e s s and prey number, while f r y held at the l o g ramp have r e l a t i v e l y low values o v e r a l l . Fry h e l d i n the 0.5 m reference s i t e ingest more food than those at the l o g ramp s i t e . In both the l o g boom and 2.0 m reference s i t e s (Figure 23), on May 22-23, copepodites were the dominant stomach content item throughout most of the 24 h p e r i o d with Bosmina s e c o n d a r i l y important. The same trends were seen i n the May 28-29 experiments. The stomach contents of 2.0 m reference s i t e f r y g e n e r a l l y had a greater number of prey species than those of l o g boom s i t e f r y (Figure 22). The higher species r i c h n e s s of prey STOMACH FULLNESS PREY NUMBER 73 Figure 22. Stomach f u l l n e s s (+ S.E.) and number of prey (+S.E.) i n stomachs of sockeye f r y during feeding experiments at boom and c o n t r o l s i t e s (May 22-23 and May 28-29, 1985) and at ramp and c o n t r o l s i t e s (June 4-5, 1985) (dashed l i n e s = c o n t r o l s i t e s , s o l i d l i n e <= treatment s i t e ) 74 items acquired by reference s i t e fry i s r e f l e c t e d in higher d i v e r s i t y . For both May 22-23 and May 28-29, species d i v e r s i t y was higher in the stomach contents of reference s i t e fry than in boom s i t e f r y (Figure 24). There were large differences in stomach contents between log dump and 0.5 m reference (Figure 23) f r y . Although copepodites were the most abundant food item over the 24 h period, chironomid larvae became the main food item during the early morning for fry at the 0.5 m reference s i t e . Cljironomid larvae were v i r t u a l l y absent from the stomach samples of fry held at the log ramp s i t e (Figure 23). Bosmina were taken at low frequencies throughout the 24 h period at both s i t e s . There was no difference in d i v e r s i t y of food items acquired by fry held at ramp and reference s i t e s . To test for prey s e l e c t i v i t y by sockeye fry in log handling vs . reference areas, several indices were applied to the data. Both Pinkas 's index of r e l a t i v e importance (1971) and Strauss' lin e a r selection index (1979) f a i l e d to represent the feeding patterns of the sockeye salmon. The sporadic appearance of chironomid larvae and th e i r corresponding consumption are represented as a preference for chironomid larvae over copepodites. However, the absence of chironomids in both zooplankton and gut samples at other times re s u l t s in their representation as a randomly selected food item, which i s not a b i o l o g i c a l l y reasonable conclusion. Therefore, these two MAY 22-23 MAY 28-29 JUNE 4-5 1.0 0.8 0.6 0.4 0.2 "•"'ilium BOOM 04 08 12 16 20 24 04 08 0.4 0.2 08 12 16 20 24 04 08 04 RAMP 08 12 16 20 24 04 08 Time (h) Figure 23. Gut contents (proportion (transformed by square root arcsin) of number of each prey type) for sockeye fry held at boom and reference s i tes (May 22-23 and May 28-29, 1985) and ramp and reference s i tes (June 4-5) (white = copepodites, sparse dots = Bosmina. l i gh t str ipes = other, dark str ipes = Diacyclops. and denser dots = chironomid larvae) . MAY 22-23 Q CO z o CO CL 1 CO o * — i 1 i \ 0.8 T 04 08 12 16 20 24 04 08 MAY 28-29 04 08 12 16 20 24 04 08 TIME(h) Figure 24. D i v e r s i t y i n d i c e s (Simpson's D) f o r gut contents of sockeye f r y h e l d at boom, ramp and c o n t r o l s i t e s . 77 s e l e c t i v i t y ind ices were discarded as methods to describe the feeding of sockeye fry over the course of 24 h experiments. 3.4 DISCUSSION The r e s u l t s of the dye experiment suggest extreme s t r a t i f i c a t i o n in response to densi ty d i f fe rences in the surface water within the log storage s i t e . The stagnant condi t ion of t h i s water contr ibutes to oxygen deplet ion due to high B.O.D. and C.O.D. Oxygen l e v e l s were lowest (<2 mg/l) in the top 0.25 m of the water column which corresponds to the most poorly mixed water l a y e r , as demonstrated in the dye experiments. Dissolved oxygen monitoring in the Houston Forest Products s i t e during May and June, 1986 (Bustard 1986) determined that oxygen leve ls again were depressed (3-5 mg / l ) , but not to the same extent as in 1985. The oxygen depression remained u n t i l the log booms were removed from the s i t e . Long term temperature data (Bustard 1986) ind icate that condi t ions were not unusual during 1985 and 1986, which suggests that t h i s phenomenon i s not anomalous and may occur on a year ly basis in la te May/early June. The downstream migration of sockeye f ry from Morrison River into Morrison Arm i s coinc ident with the oxygen deplet ion in the log storage area. It has c l e a r l y been shown by Levy et a_l. (1985b) that fry avoid the log storage area during t h i s t ime. Avoidance of oxygen depleted water has been shown for other f i shes (Davis 1975) and may be a resu l t of increased random movement u n t i l preferred 78 oxygen condi t ions are found. Increased predat ion r i sk and/or energy expenditure as a resu l t of avoidance behaviours might increase the morta l i ty rate of f ry passing through the log storage a rea . This hypothesis could be tested using a mark-recapture experiment in which f ry are marked as they leave Morrison R iver , and then recaptured af ter the log storage area . The other side of Morrison Arm could be used as a c o n t r o l , assuming that young f ry do not cross the arm. It would not be poss ib le to a t t r ibu te mor ta l i ty to i n d i v i d u a l f a c t o r s , but d i f f e r e n t i a l morta l i ty would suggest higher r i s k s in passing through the log storage area . C e r t a i n l y , the r e s u l t s of the in  s i t u bioassay experiments ind icate that f ry enter ing the surface waters of the log storage area during la te May and ear ly June would have d i e d . Schools of apparently d isor ien ted sockeye f ry were observed within the booms during ear ly June, 1985 (pers. o b s . ) , but no bodies were found. Prey consumed by sockeye f ry in FTEs were s imi la r to d ie t items prev ious ly reported for f ry in Morrison Arm (Levy et a l . 1984). A l s o , the zooplankton samples from the reference FTEs have a s im i l a r composition to lake samples which ind icates that the food ava i l ab le to f ry ins ide the FTEs i s representat ive of the lake . However, i t i s poss ib le that t h i s i s a sampling a r t i f a c t since the zooplankton sample volumes were greater than FTE volumes. Consequently, zooplankton could have been drawn into enclosures resu l t ing in a sample which may not be representat ive of what i s a v a i l a b l e to f r y . Assuming that t h i s e f fec ts w i l l be equal at treatment and reference s i t e s , I w i l l a t t r ibute d i f fe rences in fry d ie t between reference and treatment s i t e s to the e f fec ts of log storage, through (1) food a v a i l a b i l i t y and (2) sockeye f ry feeding behaviour under log storage water qua l i t y condi t ions in the log storage area . The amount and d iges t ive status of the gut contents r e f l e c t s a unimodal feeding pa t te rn , with feeding occurr ing from ear ly morning to the afternoon of each day. This pattern was a lso descr ibed by McCart (1967) for inshore f ry feeding in Babine Lake during ear ly June. The number of empty stomachs was inverse ly re la ted to the mean stomach f u l l n e s s for a l l sample t imes. Sockeye f ry held in the log boom and 2.0 m reference s i t e s (May 22-23 and May 28-29) showed no major d ie tary d i f fe rences that were consistent for both sample dates . There were only s l i g h t d i f fe rences in the food ava i lab le to the f ry at those two s i t e s , although food was general ly more abundant at reference s i t e s . There was a tendency towards higher prey d i v e r s i t y acquired by the reference s i t e f r y , as evidenced on both experiment dates by a more complex prey species composition in gut samples. It i s d i f f i c u l t to pred ic t the e f fec ts of t h i s d i f fe rence on the growth or s u r v i v a l of sockeye f r y . However, i t i s genera l ly accepted that reduced food d i v e r s i t y is a de le te r ious consequence of p o l l u t i o n and disturbance (Washington 1984). 8 0 Sockeye f ry in log dump and 0.5 m reference s i t e s (June 4-5) d isplayed major d ietary d i f f e r e n c e s . Fry held in cages in the log dump s i t e acquired s i g n i f i c a n t l y fewer prey items r e s u l t i n g in low- stomach f u l l n e s s and the species composition was markedly d i f f e r e n t . The abundance of copepodites, the major food item of sockeye f ry in May and June was s l i g h t l y higher in the reference s i t e than in log dump s i t e s for the majority of the day and th is trend i s r e f l e c t e d in the consumption of t h i s prey. S i g n i f i c a n t l y greater numbers of copepodites were consumed in the reference s i t e compared to the log ramp s i t e . Other food items such as Diacyclops and Bosmina do not exh ib i t t h i s same pattern in e i ther abundance or consumption; these prey items are r e l a t i v e l y low in abundance and d id not s i g n i f i c a n t l y d i f f e r in consumption between s i t e s . The cont ro l s i t e f ry consumed large numbers of chironomid larvae which become a v a i l a b l e to them during the morning and evening while t h i s pre fer red prey item was not ava i l ab le to f ry in the log dump. These r e s u l t s suggest that sockeye f ry which feed in the h igh ly d is turbed inshore area of the log ramp w i l l experience lower food abundance and a d i f f e r e n t d ie t composition than those feeding in a p r i s t i n e inshore environment. Sockeye f ry feed pr imar i ly on water column prey, so the presence of chironomid larvae in zooplankton and stomach samples was an unexpected r e s u l t . However, these chironomid larvae appear to undergo small v e r t i c a l migrations in the morning and evening, which puts them 81 into the "ava i lab le" food supply for sockeye f ry in shallow waters at those t imes. In gut analyses during 1984 and 1985, Levy et a l . (1985a,1985b) a lso found chironomid larvae in stomach samples from sockeye f r y . It appears that the sockeye f ry in May/June acquire prey items in proport ion to the i r abundance in the environment. However, Rankin (1977) in a laboratory study of prey s e l e c t i v i t y by young Babine Lake sockeye f ry found that Diacyclops and Diaptomus adults were se lected over copepodites. He suggested that low abundance of adul ts in Babine Lake may resu l t in increased predation on the smaller copepodites and n a u p l i i , which might be the case in Morrison Arm during May and June. In the la te summer and ear ly f a l l , Babine Lake sockeye depend mainly upon adult zooplankton (McDonald 1973, Rankin 1977) as has been observed for sockeye fry in Lake Washington (Doble and Eggers 1978). This feeding s h i f t from juveni le to adult zooplankton may r e f l e c t the growth of ava i l ab le food items and/or an improved a b i l i t y of f ry to capture larger food items as they grow and move o f fshore . The absence of chironomid larvae i s re la ted to disturbance from log handling a c t i v i t i e s . Severe impacts of log storage on a l l major groups of benthic invertebrates have been well documented for the Houston Forest Products dump s i t e (Levy et a l . 1985b, Yesaki and Levy 1986). In add i t ion to phys ica l disturbance from bark deposi t ion and boom boats (Conlan and 82 E l l i s 1979) the abundance of benthic invertebrates may be re la ted to the chemical changes to the environment which accompany log storage. Levy et a l . (1985b) demonstrate that the microbia l growth under the log boom has a high rate of oxygen consumption and i s associated with hydrogen sulphide product ion . Measurements of sediment oxygen-reduction potent ia l in the Nanaimo River estuary show the presence of an anoxic layer over the benthos at log storage s i t e s where logs had been removed (McGreer et a l . 1984). Sockeye f ry seem to p r e f e r e n t i a l l y feed on chironomid larvae over copepodites when both are a v a i l a b l e ; whether for taste or energet ic reasons. It seems reasonable that chironomid larvae would be r e l a t i v e l y easy to capture and resul t in a large energy gain r e l a t i v e to the foraging e f f o r t i f they are abundant. Chironomid larvae are probably not a staple food item, as supported by stomach content ana lys is of l i t t o r a l sockeye f ry c o l l e c t e d throughout Babine Lake (Levy et a_l. 1984), and appear to be o p p o r t u n i s t i c a l l y consumed. It i s the presence of chironomid larvae which accounts for the s h i f t in d ie t composition observed for f ry held in reference v s . log ramp s i t e s . Levy et a_l. ( 1982) a lso documented a d i f fe rence in d iet composition between a log handling s i t e and a cont ro l s i t e in the Fraser River estuary, B r i t i s h Columbia, which was re lated to food a v a i l a b i l i t y at those s i t e s . The proport ion of insects (adul t , pupae, and larvae) consumed by released chinook fry ( Oncorhynchus tshawytscha ) was greater in the undisturbed marsh 83 than in the log storage area . In f a c t , insect pupae or larvae were not taken as food by chinook in the log storage area. The a v a i l a b i l i t y of insects as a food item seems to be p o s i t i v e l y re la ted to the presence of marsh plants which are detr imenta l ly a f fec ted by estuar ine log storage, p a r t i c u l a r l y over t i d a l f l a t s (Levy et a l . 1982). I am aware of only one other experimental study that examines f i s h feeding in log storage areas. A s imi la r project on feeding by, chum salmon ( Oncorhynchus keta ) was conducted in the well f lushed Nanaimo estuary, B r i t i s h Columbia using experimental enclosures in log storage and undisturbed s i t e s (McGreer et a l . 1983). No large d i f fe rences in e i ther prey abundance or d ie t composition were found between s i t e s , which corroborates the r e s u l t s of the boom experiments in the present study. Not s u r p r i s i n g l y , food q u a l i t y and quant i ty appears to be re la ted to the in tens i ty and frequency of use log handling s i t e s rece ive . Juveni le salmon feeding in s i t e s which are r e l a t i v e l y wel l f lushed and l i g h t l y used may not be measurably a f fec ted by log storage. However, s i t e s which have r e s t r i c t e d mixing (Pease 1974) and heavy use (eg. log ramp area) may reduce water qua l i t y and abundance of food to l e v e l s which can a f fec t movement and feeding of juveni le salmon f r y . The reduced abundance of zooplankton, p a r t i c u l a r l y copepodites, in the inshore surface waters of the log ramp s i t e may be re la ted to oxygen dep le t ion . Levy et a l . (1985b) conclude 84 that zooplankton are i n s e n s i t i v e to water q u a l i t y condi t ions within the log handling s i t e . However, the i r sampling regime did not include surface waters (< 1.0 m), where water q u a l i t y was poor enough to expect a negative response by zooplankton. Therefore, the i r conclusions were only v a l i d for zooplankton at depths greater than 1.0 m, where oxygen condi t ions are better than those in surface waters. As demonstrated in the enclosure experiments (Chapter 2) , zooplankton do respond to the changes in water q u a l i t y which accompany log storage. L ign in - tann in and oxygen concentrat ions in the enclosure experiments under three and f i ve log experiments are s imi la r to those observed in the log storage s i t e during May and June in both 1985 and 1986 (Levy et a l . 1985b, Bustard 1986). This suggests that the s t a t i c enclosure experiments are representat ive of the f i e l d s i t u a t i o n . From the resu l ts of the log ramp experiment, i t seems that sockeye f ry obtain reduced amounts of food under such c o n d i t i o n s , probably as a resu l t of the s l i g h t l y depressed oxygen condi t ions as well as lower food a v a i l a b i l i t y . Di f ferences in oxygen between reference and treatment s i t e s were not c o n t r o l l e d f o r , and there fore , must be assumed to be part of the boom or ramp treatments. The combination of these factors during the c r i t i c a l ear ly weeks of a f r y ' s existence may reduce i t s s u r v i v a l and growth (Braum 1967). 85 It i s not poss ib le to quant i ta t i ve ly compare the log boom and log ramp feeding experiment r e s u l t s because the s i t e s are located in waters of d i f f e r e n t depths and, accord ing ly , zooplankton populat ions and water q u a l i t y d i f f e r . This i s a fundamental problem in e c o l o g i c a l research (Cairns and Pra t t , 1986) and not e a s i l y reso lved . A l s o , in t h i s study, several s i t e s within the log storage and reference areas should have been used, providing r e p l i c a t i o n to see i f observed patterns are reproducib le . Another problem, common to environmental impact s t u d i e s , i s that e f f e c t s must be in fer red from s p a t i a l pattern alone when the impact has already occurred (Green 1979). I must assume that observed d i f fe rences between reference and treatment s i t e s would not have ex is ted i f the log storage f a c i l i t y had not been i n s t a l l e d . The data suggest that the e f fec ts of log handling a c t i v i t i e s on food supply are greater at the log ramp s i t e than at the log boom s i t e . This i s reasonable, given that t h i s s i t e i s used a c t i v e l y and more in tens ive ly than the log storage s i t e . More important ly , the ramp s i t e i s located within the bay, enclosed by log booms and subjected to greater phys ica l and chemical in f luence , so water q u a l i t y , zooplankton and benthos at that s i t e are more severely a f f e c t e d . These changes t rans la te into a change and reduction in food supply ava i lab le to sockeye f ry and the flow through enclosure experiments demonstrate that food intake by f ry i s reduced. However, i t may be that the water 86 qua l i t y changes which occur in the log storage area are more important. Fry a c t i v e l y avoid the log storage area probably due to severe oxygen deplet ion and, there fore , may never encounter areas of a l te red food supply. The e f f e c t s described here are l o c a l i z e d and s i t e s p e c i f i c , and I can only hypothesize that sockeye fry exposed to these e f fec ts might be exposed to higher morta l i ty r a t e s . The sockeye habitat a f fec ted with respect to water qua l i t y and food supply i s a substant ia l proport ion of the lake shorel ine ava i lab le to post l a r v a l sockeye. 87 4. BIOASSAY EXPERIMENTS 4.1 INTRODUCTION The study of de le ter ious e f f e c t s of chemicals on aquatic organisms (aquatic toxicology) may include measurement of m o r t a l i t y , growth, reproduction and other parameters a f fec ted at the sublethal l e v e l (Rand and P e t r o c e l l i 1985). Evaluat ion of the t o x i c i t y of compounds i s most often accomplished through bioassay tes ts which quant i fy the response of organisms to the tox ican t . From bioassay r e s u l t s , "safe" l e v e l s for compounds can be determined (Rand 1980) which gives dec is ion makers basic information to use for regula t ing and c o n t r o l l i n g toxic substances. There are standard procedures which can be used to obtain widely comparable data on t o x i c i t y . In genera l , acute and chronic bioassays examine short term (usual ly l e tha l ) and long term (usual ly chronic or sublethal ) e f f e c t s . Standard aquatic bioassay organisms include a wide range of invertebrates and f i s h (APHA et a_l. 1985), but most commonly rainbow trout ( Salmo  ga i rdner i ) and Daphnia are used. These organisms are easy to cu l ture and maintain, r e l a t i v e l y inexpensive and have a long h i s t o r y of use in the l i t e r a t u r e (APHA et a l . 1980). For these reasons, I chose rainbow trout and Daphnia as test organisms for bark leachate b ioassays, in add i t ion to sockeye salmon f r y , a l l of which are resident in the environment being a f fec ted by log 88 storage. It i s wel l documented that bark and wood leachates are tox ic (Tabata 1964, Atkinson 1971, S e r v i z i et a l . 1971, Schaumburg 1973, Pease 1974, Buchanan et aJL. 1976, and Peters et a l . 1976). However, much of t h i s t o x i c i t y work i s incons is ten t , as wel l as fragmented and scat tered by d i f fe rences in methodology, tree species and leachate concentra t ions. Therefore , i t was necessary to determine t o x i c i t y for bark leachates which would be app l icab le to the Babine Lake system. A l s o , severa l authors (Pease 1974, Conlan 1975) have shown that the t o x i c i t y of wood leachates i s higher in freshwater than in seawater because l i g n i n compounds p r e c i p i t a t e out in s a l t water, reducing t o x i c i t y . As a r e s u l t , there i s a greater po ten t ia l for tox ic e f f e c t s to be s i g n i f i c a n t in freshwater (Sedel l and Duval 1985). The main purpose of these acute bioassays was to explore the range over which acute t o x i c i t y e x i s t s . Short-term tes ts are acknowledged (Rand 1980) as being the f i r s t step in the study of the tox ic e f f e c t s of a chemical compound. Acute tes ts can provide values for comparison of toxicant l e t h a l i t y between test organisms or tox ican ts . A 96h-LC-50 can be defined as the quant i ty of tox ic substance in the test so lu t ion that produces 50% morta l i ty in test organisms which are exposed for 96 hours. However, acute tes ts can not be used to pred ic t a "safe" toxicant concentrat ion which would be un l i ke ly to harm the 89 ecosystem (Buikema et a l . 1982). When a chemical compound i s not l e t h a l l y toxic i t does not fol low that i t has no adverse e f f e c t s . Chronic t o x i c i t y tes ts permit assessment of adverse e f f e c t s on several l i f e stages of test organisms. It became evident from the l i t e r a t u r e and the present study that acutely tox ic bark leachate concentrat ions were higher than those usual ly measured in the f i e l d . Therefore, a study of the sublethal e f f e c t s of bark leachate was undertaken. As far as I can determine, nothing has been publ ished concerning the % sublethal e f f ec ts of bark or wood leachate. The object ive of t h i s study is to determine the t o x i c i t y of bark leachate at (1) the l e t h a l l e v e l , to have a standardized measure which can be compared to l i t e r a t u r e values and (2) the sublethal l e v e l , to examine the e f f e c t s of bark leachate concentrat ions s imi la r to those measured in the f i e l d . Bark leachates (pine and spruce) produced by s t a t i c leaching for d i f f e ren t lengths of time are tested for l e t h a l t o x i c i t y using Daphnia, rainbow t rou t , and sockeye salmon f r y . Sublethal bark leachate concentrat ions are tested in long term bioassays for the i r e f fec t on mor ta l i t y , reproduct ion, molting and growth of Daphnia neonates. I predict that the L-T concentrat ion of bark leachates w i l l increase with the length of time the bark i s allowed to leach 90 under s t a t i c cond i t ions ; in conjunct ion, the t o x i c i t y of leachates to Daphnia and f i s h w i l l a lso increase at both l e t h a l and sublethal l e v e l s . 4.2 METHODS 4.2.1 Daphnia bioassays ! • Z - l ' l Test organisms The Daphnia cu l ture and f a c i l i t i e s of the Environmental Engineering Lab, Un ivers i ty of B r i t i s h Columbia were used from February to A p r i l , 1985 for a l l bioassay t e s t s . A brood stock of Daphnia pulex was set up in a 4.0 1 g lass beaker in a constant environment chamber where the temperature was maintained at 19.5+ 0.5 deg. C with a l i g h t regime of 14 h l i g h t and 10 h dark. The brood stock was maintained at low d e n s i t i e s by siphoning of f hal f the cu l ture every two weeks and adding f resh d i l u t i o n water. Daphnia were cu l tured in a medium descr ibed by Horvath and Russo (unpublished) which i s prepared by adding s p e c i f i c amounts of reagent grade chemicals (Table 6) to d i s t i l l e d water. P a r t i c u l a r care was taken to determine a high surv iva l rate in th is medium. A synthet ic medium was chosen because i t s composition i s known and reproduc ib le . 91 Ta b l e 6. Chemical reagents and q u a n t i t i e s used i n p r e p a r a t i o n of Daphnia medium ( a f t e r Horvath and Russo, u n p u b l i s h e d ) . Reagent Amount added (mg/1) NaHC03 CaS0 4 x 2H20 MgS04 96 60 60 KCl 4 Daphnia were f e d every other day with a prepared mixture of a l g a e ( C h l o r e l l a , ) t r o u t chow and y e a s t . To o b t a i n the bioass a y stock, a s i n g l e female was taken from the brood c u l t u r e and p l a c e d i n a 4 oz round g l a s s j a r with 100 ml of d i l u t i o n water. Neonates were c o l l e c t e d as produced and p i p e t t e d i n t o t h e i r own j a r s . In t h i s manner, h e a l t h y b r e e d i n g females were c u l t u r e d t o produce enough g e n e t i c a l l y uniform neonates f o r b i o a s s a y t e s t s . 4.2_. K 2 Bark l e a c h a t e s o l u t i o n s Dry p i n e and spruce bark c o l l e c t e d a t a l o g dump ramp d u r i n g the summer of 1984 was s t o r e d i n s e a l e d dark p l a s t i c bags and kept a t 4 deg. C b e f o r e use i n b i o a s s a y s . Leachates were p a s s i v e l y e x t r a c t e d from bark i n a s t a t i c system with bark a t a d e n s i t y of 2.50 g per l i t r e water h e l d a t the temperature each 92 bioassay was conducted a t . Bark was added to Daphnia d i l u t i o n water at given dens i t i es and allowed to leach for 1, 2 and 5 day per iods , a f te r which time the bark was removed and the bioassays s t a r t e d . As test so lu t ions were replaced on a d a i l y b a s i s , enough leachate for the en t i re experiment was made at once, with the majori ty of i t stored at 4 deg. C for l a t e r use throughout the b ioassay. the l i g n i n and tannin concentrat ion was determined for test so lut ions by the method descr ibed in Chapter 2. Concentrations of bioassay test so lut ions were d i l u t e d as percent by volume on a volume to volume basis (eg. 10% d i l u t i o n equaTs 1 part leachate to 9 parts d i l u t i o n water) . 4.2.1.3 Short term bioassays Bioassays (96 h s t a t i c ) were conducted in dup l ica te using 100 ml volumes of s e r i a l logari thmic d i l u t i o n s of the bark leachates . Add i t iona l j a rs of the highest sample concentrat ion were set up for measuring water q u a l i t y (temperature, d isso lved oxygen, pH and conduct iv i ty ) over the course of the experiment. Neonates (< 24 h old) were randomly t ransfer red to test ja rs using a p ipet te to reach concentrat ions of 5 neonates/100 ml . Daphnia were not fed during short term bioassays (APHA et a l . 1985). Immobil izat ion, the c r i t e r i o n for death, was determined by complete lack of movement even a f te r the test jar i s rotated. The percent morta l i ty in each jar was measured at 1, 2, 8, 24, 48, 72 and 96 h. Dead Daphnia were removed and test so lut ions were changed every 24 hours a f te r determination of mor ta l i t y . 93 10T > ^ 81 < GC h-Z LU O z o o UJ I-< X o < LU 6-4 96h-LC-50 2 20 40 60 80 PERCENTAGE MORTALITY 100 Figure 25. Example of graphica l in te rpo la t ion for c a l c u l a t i o n of 96h-LC-50. This graph i s for Daphnia in 5 day spruce bark leachate . 94 Estimation of 96h-LC-50 was made by graphic in te rpo la t ion (APHA et a l . 1985, Atwater et a l . 1983, Par r i sh 1983). According to standard methods (APHA et a l . 1985), a LC-50 i s an in terpola ted value based on percentages of organisms dying at two or more concentrat ions which produce greater and lesser than 50% m o r t a l i t y . These data are p lo t ted on semilog paper with the log of concentrat ions v s . percentage mor ta l i ty (see e g . , Figure 25). A s t ra ight l i n e i s drawn between successive concentrat ions and the point where the l i n e crosses the 50% morta l i ty point i s the estimated LC-50 va lue . 4 J _ . 4 _ Long term bioassays Daphnia were used to assess sublethal t o x i c i t y of bark leachates because they grow to reproductive age in <10 days and severa l c lutches can be produced in a 30 day test pe r iod . Long term bioassays for Daphnia were conducted using s e r i a l logar i thmic d i l u t i o n s of 2.5 g bark/1 water so lu t ions of spruce and pine bark, leached for 24 h. Water q u a l i t y was monitored every other day; oxygen l e v e l s were maintained above 6.0 m g / l . Twenty neonates (<24 h old) were used for each test d i l u t i o n and maintained in 20 separate 100 ml j a r s . Daphnia were fed every 1 to 3 days during the 30 day experiments. Test organisms were monitored for m o r t a l i t y , molt ing and neonate production every other day, at which time test so lu t ions were changed. Neonates produced during the experiments were counted.and d iscarded. 95 4.2.2 F i s h Bioassays 4.2.2.1 Test organisms Two f i s h species were used for short term bioassay: sockeye salmon ( Oncorhynchus nerka ) and rainbow trout ( Salmo  qa i rdner i ). Sockeye salmon (mean fork length = 2.9 cm) were obtained from Fulton River spawning channel , Babine Lake, B .C . and maintained in r i v e r water in holding tanks at the Department of F i s h e r i e s and Oceans laboratory located there . Fry were fed d a i l y with Oregon Moist P e l l e t s . Sockeye salmon produced in the Fulton River spawning channel had a high incidence of in fec t ious hepat ic necrosis ( I .H.N.) disease during the 1984 f i e l d season (egg-fry surv iva l rate of 7%, Stu Barnetson pers comm); however, during the 1985 f i e l d season the egg- f ry s u r v i v a l rate (61%) was above average. Fry samples analyzed by Garth Traxler ( P a c i f i c B i o l o g i c a l Stat ion) ind icated that the i n f e c t i o n incidence of t h i s disease was 41% in the l ab -he ld sockeye used in bioassay experiments during 1985. Rainbow trout f ry (mean fork length = 2.6 cm) were obtained in March, 1985 from Sun Va l ley trout farms, a commercial suppl ie r in the Fraser V a l l e y , B r i t i s h Columbia. These f ry were maintained in holding tanks with dechlor inated water at the Un ivers i ty of B r i t i s h Columbia, B .C . and fed Oregon moist p e l l e t s on a d a i l y b a s i s . 9 6 i . *2«2.2 Short term bioassays Bark leachates for f i s h bioassays were produced by the same methods used for Daphnia b ioassays , except that Fulton River (sockeye salmon) and dechlor inated water (rainbow trout) were used and samples were leached at 10+2 deg. C. Experiments were run with natural photoperiod ( approx. 14 h: l0 h of l i g h t : d a r k ) . Bioassays were conducted in g lass aquaria with 20 f i s h in 20 1 of test s o l u t i o n , which i s wel l below the maximum suggested loading densi ty of 1g/3 1/day for s t a t i c bioassays (APHA et a l . 1985). A l l aquaria were aerated with compressed a i r v i a glass p ipet tes to maintain d isso lved oxygen concentrat ions above 8 m g / l . Temperature regulat ion was accomplished by s i t u a t i n g bioassay aquaria in t rays with f lowing water. Water q u a l i t y was monitored (temperature, d i s s o l v e d oxygen, pH and conduct iv i ty ) d a i l y in a l l aquar ia . S e r i a l logari thmic d i l u t i o n s of bark leachates in dupl icate were used for 96h-LC-50 bioassays as descr ibed in Standard Methods (APHA et a l . 1985). Mor ta l i ty was measured at 1, 2, 8, 24, 48, 72 and 96 h and dead f i s h were immediately removed from aquaria and fork length and weight were recorded. Observations on the behaviour of test f ry were a lso noted. 96h-LC-50 values were determined by s t ra ight l i n e in te rpo la t ion (Figure 25). 97 4.3 RESULTS 4_.3.j_ Bark leachate L ign in - tann in concentrat ions produced by bark in waters used for bioassays var ied only s l i g h t l y between Daphnia and f i s h experiments (Figure 26). Bark leaching seemed to be equivalent in Daphnia medium, Fulton River water and dechlor inated water from U . B . C , although occurr ing at temperatures ranging from 9.0 to 19.5 deg. C. Using L-T concentrat ions as an i n d i c a t o r , spruce bark produced much higher concentrat ions of coloured mater ia ls than pine bark. A f te r two days, leachate concentrat ion leve led out in both tree s p e c i e s , remaining the same at f i ve days as for two. 4.3.2 Daphnia bioassays 4.3_.2.J_ Short term tes ts Pine bark leachates were not tox ic to Daphnia neonates in 96h l e t h a l bioassay tes ts (Table 7) . In 1, 2 and 5 day leaching experiments for pine bark there was >90% s u r v i v a l at a l l leachate concentrat ions and c o n t r o l s . For spruce bark, the 1, 2 and 5 day leachates caused s i g n i f i c a n t mor ta l i ty in neonates exposed in the 96h l e t h a l bioassay t e s t s . 96h-LC-50 values (Table 7) ind icate that acute t o x i c i t y to neonates decl ined with 98 2 0 0 T SPRUCE Daphnia A A rainbow •—•sockeye H— I—i—I—l—I— I— I 0 2 4 6 8 LEACHING PERIOD (days) Figure 26. L ign in - tann in concentrat ions (mg/l) produced over time under s t a t i c condi t ions (2.5 g bark/1 water) for Daphnia and f i s h b ioassays . 99 l e a c h i n g time. Table 7. 96h-LC-50 valu e s [L-T c o n c e n t r a t i o n (%v/v)3 f o r Daphnia neonates u s i n g p i n e and spruce bark l e a c h a t e (2.5 mg/l) under uniform bioassay c o n d i t i o n s (mg/l t a n n i c a c i d as measured L-T a n a l y s i s (APHA et a l . 1985). Leaching time Pine Spruce (days) mq/1 (%v/v) 1 not l e t h a l 41 (58 %) 2 not l e t h a l 67 (50 %) 5 not l e t h a l 73 (57 %) 4.3.2.2 Long term t e s t s S u b l e t h a l b i o a s s a y s w i t h Daphnia neonates r a i s e d over a 30 day p e r i o d demonstrate t h a t spruce bark l e a c h a t e i s more t o x i c than t h a t of pine bark. Long-term s u r v i v a l was h i g h e s t f o r neonates r a i s e d i n pine bark l e a c h a t e s ( F i g u r e 27), p a r t i c u l a r l y a t higher c o n c e n t r a t i o n s . Neonates i n 100% spruce bark l e a c h a t e were a l l dead (n = 20) a f t e r 7 days, whereas s e v e r a l neonates i n 100% pine bark l e a c h a t e s u r v i v e d u n t i l day 27 of the experiment. Oxygen l e v e l s and other water q u a l i t y parameters were w e l l w i t h i n a c c e p t a b l e l e v e l s i n a l l treatments r e l a t i v e t o c o n t r o l s . The p r o p o r t i o n of neonates producing c l u t c h e s i n bark l e a c h a t e s o l u t i o n s was h i g h e r f o r pine bark than spruce bark (Table 8 ) . The p r o p o r t i o n of r e p r o d u c t i v e Daphnia decreased with i n c r e a s e d l e a c h a t e c o n c e n t r a t i o n i n both cases (Friedman two way TIME (days) Figure 27. Surv iva l of paphnia neonates (n = 20) grown over 30 days in chronic bioassays for spruce and pine bark leachates . Each l i n e represents a s e r i a l d i l u t i o n of leachate , ranging from 0% to 100% concentra t ion . 1 0 1 ANOVA, p < 0.001). Table 8. Proport ion of i n i t i a l Daphnia neonate number (n = 20) that produced at least one c l u t c h in long term bioassays for spruce and pine bark leached for one day. Leachate (%v/v) Spruce Pine 100 56 32 10 5.6 0 0 0 0 0.45 0.80 0.65 0.05 0.50 0.60 0.70 0.80 0.85 The mean number of neonates produced per reproducing female was higher for Daphnia ra ised in pine bark leachate compared to spruce bark leachate (Figure 28). Neonate production decreased with increased leachate concentrat ions and there were s t a t i s t i c a l l y s i g n i f i c a n t reduct ions in number of neonates produced between d i f f e ren t concentrat ions of both pine and spruce bark leachate (Kruskal -Wal l is one way ANOVA, p< 0.001). 4.3.3 F i s h bioassays Pine bark leachates were l e s s tox ic than spruce bark leachates to both rainbow trout and sockeye salmon fry (Table 9) . In f a c t , a f te r leaching for one and two days, pine leachate produced no morta l i ty in bioassay f i s h . Only a f te r leaching pine bark for f i v e days was i t poss ib le to c a l c u l a t e a 96h-LC-50. Spruce bark leachates became more toxic with longer leaching C o c c CO CD :> 17 40 T 30 n«13 0) a co co 20 CD 1 :• 10 16 16 14 12 10 1 5.6 10 32 56 100 5.6 10 32 56 100 SPRUCE PINE Leachate cone. (%v/v) Figure 28. Mean to ta l number (± S . E . ) of neonates produced per reproducing Daphnia in subletha l bioassays with s e r i a l d i l u t i o n s of spruce and pine bark (2.5 g/1) leachate (n = no. of reproducing naphnia). 103 t ime, as demonstrated by a decrease in L-T values at LC-50. Table 9. 96h-LC-50 values (L-T concentrat ion mg/l (%v/v)) for rainbow trout and sockeye salmon f ry using pine and spruce bark leachate . Leaching time(days) 1 2 5 RAINBOW Pine Spruce mo/l(%vZv) not tox ic not tox ic 15 (44%) 51 (73%) 33 (24%) 22 (16%) SOCKEYE Pine Spruce mg/l(%v/v) not tox ic not tox ic 12 (30%) 42 (54%) 32 (24%) 16 (12%) Sockeye salmon f ry were more suscept ib le than rainbow trout to the tox ic e f f e c t s of bark leachate . For a l l leachates, sockeye salmon reached 96h-LC-50 at lower concentrat ions of L-T than rainbow trout (Table 9) . For both sockeye and rainbow fry b ioassays , s u r v i v a l of cont ro l f i s h was always 95%. 4.2 DISCUSSION The short term bioassay tes ts achieved the ob ject ives of explor ing the range of bark leachate t o x i c i t y and producing r e l a t i v e t o x i c i t y values for comparative purposes. Bark leachate i s acutely t o x i c ; i t can k i l l 50% or more of the test organisms in a short per iod of time i f at high enough concentrat ions (Rand and P e t r o c e l l i 1985). The var iab les which determine the bark leachate concentrat ion are (1) bark/water r a t i o (2) leaching 104 time (3) tree species and (4) poss ib ly other var iab les which I d id not determine. It has been shown in the present study and in other studies (Graham 1970, S e r v i z i et a l . 1971, Schaumburg 1973) that the loading l e v e l (wood/water) i s p o s i t i v e l y re la ted to leachate concentra t ion . Therefore, t h i s parameter was held constant to examine the e f fec t of leaching time over a r e a l i s t i c time range; most s t a t i c laboratory studies of bark leachates span leaching per iods of t h i r t y days or more (Graham 1970, Sproule and Sharpe 1970, Schaumburg 1973). There were s i g n i f i c a n t d i f fe rences in the L-T concentrat ions and often the t o x i c i t y of bark leachates produced over short time periods in my experiments. For Daphnia, pine bark leachates were not acutely t o x i c , although L-T concentrat ion d id increase a f te r one day to concentrat ions above 30 m g / l , where i t s t a b i l i z e d . In spruce bark leachates , L-T concentrat ion increased dramat ica l ly between days 0,1 and 2. This increase was not accompanied by increased t o x i c i t y . Per unit L - T , t o x i c i t y to Daphnia neonates a c t u a l l y decreased with increased leaching time, qui te the opposite to my p r e d i c t i o n . The toxic component to Daphnia may be v o l a t i l e (Rand and P e t r o c e l l i 1985) or a c o l o u r l e s s compound. If i t e x i s t s , i t was undetectable by a l l a n a l y t i c a l methods used by Wentzell (in p r e p . ) . T o x i c i t y resu l ts for f i s h matched more c l o s e l y to my 105 p r e d i c t i o n s . Again, pine bark leachate was l e s s toxic than spruce and only acutely tox ic a f te r leaching for 5 days. For spruce both L-T concentrat ion and t o x i c i t y increased with increased leaching time, as d id t o x i c i t y to f i s h per unit L -T . This i s opposite to the r e s u l t s obtained for Daphnia, despite studies which show good agreement between Daphnia and f i s h bioassay tes ts (Atwater e_t a l . 1983). This anomaly underl ines two of the main problems of acute t o x i c i t y tes ts which seem to be recognized but not emphasized in aquatic toxicology research. Chemical compounds can cause d i f f e r e n t responses under a var ie ty of test condi t ions (Buikema et a l . 1982). For example, in the present study, due to the requirements of Daphnia and f i s h , they must be tested at d i f f e r e n t temperatures and in d i f f e r e n t d i l u t i o n media which may a f fec t the a c t i v i t y and behaviour of toxic compounds. Consequently, the measured t o x i c i t y of a compound may d i f f e r s u b s t a n t i a l l y between experiments (Sprague 1970, Rand and P e t r o c e l l i 1985). A l s o , the systematic e f fec ts of chemicals may be d i f f e r e n t for d i f f e r e n t organisms, depending on the mode of uptake and the corresponding e f f e c t . This point leads to the second problem in assessing t o x i c i t y of chemical compounds. Very l i t t l e i s known about the chemical structure and behaviour of many t o x i c a n t s , inc lud ing bark leachate . The t o x i c i t y of a chemical can be modif ied by t o x i c o l o g i c a l in te rac t ion and small changes in const i tuents (Rand and P e t r o c e l l i 1985). To circumvent t h i s problem some researchers have experimentally 106 extracted known compounds (eg. tropolones and l ignans) from wood and examined the i r t o x i c i t y (Peters 1974, Peters et a l . 1976). However, t h i s information i s of l im i ted use in p r a c t i c a l assessments of log leachate t o x i c i t y . I am not s a t i s f i e d with any of the current methods for charac te r i z ing or quant i fy ing bark leachate concentra t ions. These include the Pear l Benson Index, t o t a l organic carbon, C .O .D . (Graham 1970, Schaumburg 1973) and L-T concentra t ion . L-T concentrat ion i s a good ind ica tor for the amount of coloured mater ia ls present in leachate , but t h i s i s not necessar i l y re la ted to t o x i c i t y , as demonstrated in the short term Daphnia b ioassays . Unfortunately , L-T concentrat ion has not been used by any other i n v e s t i g a t o r s , and i t i s not poss ib le to compare my r e s u l t s to those obtained by others . Peters et a l . (1976) measured the acute t o x i c i t y of l ignan (a re la ted compound) to coho fry and obtained 96h-LC-50 values of 60 and 64 mg l ignan/1 which i s in the same order of magnitude as for l i g n i n s in the present study. There were d i f fe rences in the t o x i c i t y of bark leachates to rainbow trout and sockeye salmon. Sockeye salmon reached LC-50 at lower %v/v and L-T concentrat ions than rainbow t rou t . This d i f fe rence i s not surpr is ing since rainbow trout are noted as being easy to cu l ture (APHA et a l . 1985), which suggests they are hardier than sockeye salmon. A l s o , the sockeye salmon fry in the Fulton River system had a r e l a t i v e l y high incidence of I .H.N, disease in 1985. This disease may make them more suscept ib le to s t resses (Garth T r a x l e r , pers comm) which would 107 include exposure to tox ican ts . I d id not have s u f f i c i e n t bioassay data to construct a dose response curve which may have provided me with more information on fac tors a f f e c t i n g the t o x i c i t y of bark leachates (Buikema et al^. 1982) and an i n d i c a t i o n of when acute l e t h a l i t y ceases (Rand 1980). Sprague (1970) emphasizes that modifying environmental condi t ions (eg. D.O.) great ly modify t o x i c i t y and d iscusses severa l examples from the l i t e r a t u r e . For pulp and paper m i l l wastes, Alderdice and Brett (1957) determined that reduced D.O. concentrat ion lowered LC 50 va lues , perhaps due to higher resp i ra tory ra tes . In the case of wood leachates , i t appears that d isso lved oxygen l e v e l s may be the operative l e t h a l agent rather than leachate, as was determined for f ry In i n s i t u .bioassay experiments (Chapter 3) . P icker ing (1968) found that d isso lved oxygen replaced z inc as the main morta l i ty agent in bioassays with Lepomis. As a r e s u l t , subletha l bioassays to test breathing rates and resp i ra tory i r r e g u l a r i t i e s such as coughing have been developed (Walden et a l . 1970) and would perhaps be sui ted to detect ing toxic e f f e c t s of wood leachates . However, for the purposes of t h i s study, I was able to demonstrate that acute l e t h a l i t y occurred at bark leachate concentrat ions higher than those measured in the f i e l d (< 2.0 mg/l L -T ; Levy et a l . 1985b). Therefore, i t i s un l ike ly that m o r t a l i t i e s such as those measured in acute lab bioassays would occur in the Morrison Arm log storage area . The bark weight to water volume r a t i o should be measured as bark surface area to 108 water volume since the surface area of the bark determines the amount of ex t rac t ives leached (Wentzel l , in p r e p . ) . In the 1984 f i e l d season, bark treatments were used in enclosure experiments and a 0.25 g bark/1 load produced greater leachate concentrat ions than the 1 log (0.24 g bark/1) treatment in 1985. Schaumburg (1973) a lso found that nearly a l l the colour i s contr ibuted by bark, compared to wood. A l s o , a higher percentage of ex t rac t ives are found in the inner bark, r e l a t i v e to the outer bark (Wentzel l , in prep.) so I would expect " loose" bark to produce leachates with a higher t o x i c i t y than "attached" bark. The t o x i c i t y of whole spruce and pine logs was examined in Chapter 2 in enclosure experiments which more r e a l i s t i c a l l y simulate condi t ions in the surface waters of a log storage area. Another way of examining the tox ic e f f ec ts of bark leachates at concentrat ions near those measured in the f i e l d is by conducting chronic b ioassays . By determining the concentrat ion of a chemical that w i l l in te r fe re with normal growth, development or reproduct ion, a more sens i t i ve measure of t o x i c i t y than acute l e t h a l i t y i s obta ined. Spruce bark leachate was more toxic than pine bark leachate in chronic b ioassays, which supports the r e s u l t s of the short term b ioassays . S i m i l a r l y , t o x i c i t y increased with leachate concentrat ion to the point where a l l test organisms in the 100 %v/v so lu t ions d ied before the end of the 30 day experiment. Neonates ra ised in the most d i l u t e leachate concentrat ions (5.6 %v/v) had s u r v i v a l rates very s imi la r to c o n t r o l s . Surv iva l 109 rates in chronic tes ts i l l u s t r a t e that leachate concentrat ions which d id not cause morta l i ty in short term bioassays can be c h r o n i c a l l y l e t h a l over the l i f e t i m e of an i n d i v i d u a l . In a d d i t i o n , subletha l bark leachate concentrat ions reduced the proport ion of reproducing Daphnia and the i r fecundity (neonate product ion) , that at low leachate concentrat ions ( 3 . 9 and 1 . 8 mg/l L-T for spruce and p ine , respect ive ly ) Daphnia reproduction rates were very s imi la r to those of cont ro l animals. The next step in examining the sublethal t o x i c i t y of bark leachates would be to run a long term bioassay with a logar i thmic ser ies from 10% to 1%. The concentrat ions would span the L-T concentrat ions measured in the f i e l d . Given that stagnant water condi t ions do occur in the log boom (Chapter 3 ) , i t i s poss ib le that zooplankton are d e l e t e r i o u s l y a f f e c t e d , at least at subletha l l e v e l s . The chronic bioassay r e s u l t s may i l l u s t r a t e the mechanism for reduced zooplankton abundances observed in log t reated enc losures . 110 5. GENERAL DISCUSSION The e f f e c t s of log storage on the aquatic ecosystem have been examined in a ser ies of laboratory and f i e l d experiments which focus on responses by zooplankton and juven i le salmonids. Here I s h a l l consider the consistency of the resu l ts of these experiments and the i r app l i ca t ion to f i e l d s i t u a t i o n s . The response by zooplankton to wood leachates was examined because these organisms are important to sockeye f ry as a food source (Narver 1970, Rankin 1977). In enclosure experiments, f i e l d measurements, and laboratory bioassays there i s evidence that zooplankton are reduced in abundance by the changes which accompany log storage. Short term bioassay r e s u l t s indicate that the l e v e l s of wood leachates that are l e t h a l l y toxic to zooplankton are higher than those measured in Babine Lake or in enclosure experiments, assuming the response by Daphnia to leachate is s imi la r to that of Babine Lake sockeye. Therefore, the mechanism for reduced zooplankton abundance may be l inked to chronic l e t h a l i t y or reduced fecundi ty , both of which were demonstrated for Daphnia exposed to subletha l leachate concentra t ions. A l s o , examination of zooplankton abundance over the course of enclosure experiments (Figures 10 to 13) and f i e l d measurements (Figure 20) revealed a pattern common to both; large "spikes" in zooplankton densi ty almost always occurred in cont ro l populat ions, whereas t reated populat ions remained unchanged. This may be l inked to a number of f a c t o r s , such as I l l patch iness , inadequate water q u a l i t y or reduced zooplankton fecundity in log a f fected areas . A process of v e r i f i c a t i o n by comparison of t o x i c i t y t e s t s , microcosm and f i e l d e f f e c t s i s required according to Buikema et a l . (1982), yet they make the point that t h i s kind of work has rare ly been done. I had predic ted that zooplankton d i v e r s i t y would decrease in response to the s t ress appl ied to the systems in the form of log treatments. Although spec ies ' abundancies d e c l i n e d , there was no consistent change in community d i v e r s i t y , so my resu l ts do not support the hypothesis that s t resses appl ied to a community can be determined by changes in d i v e r s i t y i n d i c e s . Th is could be for a number of reasons as discussed in Chapter 2. However, in the f i e l d experiments, zooplankton community d i v e r s i t y was cons is ten t l y lower at log boom s i t e s than at undisturbed l i t t o r a l s i t e s . If reductions in zooplankton abundance occur under condi t ions of log storage in Morrison Arm, as i s supported by my r e s u l t s , the food supply for young sockeye f ry feeding in that area i s p o t e n t i a l l y reduced. 24 h feeding experiments indicated that f ry d ie t i s sens i t i ve to small changes in food abundance. The sockeye f ry feeding experiments a lso c l e a r l y demonstrate the s ing le peak feeding time of f r y , in contrast to the feeding behaviour of f ry when they become pelagic and feed in a d i e l pattern (Eggers 1978). If the very e a r l i e s t f ry stages are the most c r i t i c a l (Braum 1967, Hjort 1914) and suscept ib le to s tarvat ion and environmental cond i t ions , then f ry enter ing the Morrison Arm log storage area may be de le te r ious ly a f fec ted (reduced food intake, s t ress due to low oxygen leve ls ) by the condi t ions within the log storage s i t e at Morrison Arm. Th is scenario i s often described in studies of environmental e f f e c t s because i t i s d i f f i c u l t to obtain d i r e c t measurements of f i s h responses to environmental c o n d i t i o n s . Oxygen concentrat ions within the surface waters of the log storage area dropped to l e t h a l l e v e l s . Avoidance of the Morrison Arm log storage area by sockeye fry during periods of low oxygen was wel l documented (Levy e_t a l . , 1985b). However, the c r i t i c a l information which i s required i s the fate of those f r y . Do they undergo higher morta l i ty rates as a resu l t of the i r contact with the log storage area? Given that the log storage area covers about one f i f t h of the lake perimeter at the head of Morrison Arm, f ry are e f f e c t i v e l y excluded from a large proport ion of the habitat ava i lab le to them upon entry to the lake from Morrison R ive r . In the marginal habi tat ava i l ab le within the log storage area , food l e v e l s are reduced. Rela t ive to the l i t t o r a l area of Babine Lake, the Morrison Arm log storage area i s only a minute f r a c t i o n of the environment ava i lab le to sockeye f ry in t o t a l . However, there are strong ra t iona les for minimizing the impact of log handling 113 a c t i v i t i e s on the Babine Lake system. F i r s t l y , deleter ious e f fec ts w i l l be f e l t exc lus ive ly by Morrison River sockeye, a wi ld stock that Department of F i s h e r i e s and Oceans i s anxious to maintain. The migration of sockeye fry from Morrison River is coincident with condi t ions which can lead to oxygen deplet ion and leachate accumulation. Secondly, the r e s p o n s i b i l i t y of minimizing or poss ib ly mi t iga t ing environmental impacts should not be sh i rked , despi te the apparent small sca le of the problem r e l a t i v e to Babine Lake as a whole. There are some simple ways to reduce the sever i ty of problems associated with log storage. Recommended p r a c t i c e s , s p e c i f i c to the Morrison Arm log storage s i t e include the fo l lowing: ( 1 ) Minimize accumulations of bark and wood debr is around the dump s i t e area, p a r t i c u l a r l y where i t comes in contact with water. Implement c o l l e c t i o n of loose bark and debr is at regular in te rva ls during ac t ive use of the s i t e . (2) Minimize the length of time the booms remain in the bay fo l lowing spring break up of the i c e . Before a thermocline develops, move booms to the dewatering s i t e near Topley Landing. (3) Consider moving booms out of the most shel tered areas f i r s t , to f a c i l i t a t e mixing by wind and reduction of the p r o b a b i l i t y of oxygen deplet ion o c c u r r i n g . ( 4 ) The aerat ion system which keeps the log storage area open in the winter could be operated b r i e f l y to d e s t r a t i f y water in areas of low oxygen. 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