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Impact of stream acidification on invertebrates : drift response to in situ experiments augmenting aluminum… Bernard, David P. 1985

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IMPACT OF STREAM ACIDIFICATION ON INVERTEBRATES DRIFT RESPONSE TO IN SITU EXPERIMENTS AUGMENTING ALUMINUM ION CONCENTRATIONS by DAVID P. BERNARD B.Sc. Honors, U n i v e r s i t y Of A l b e r t a 1976 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of Zoology) We accept t h i s t h e s i s as c o n f o r m i n g t o the r e q u i r e d s t a n d a r d ( THE UNIVERSITY OF BRITISH COLUMBIA October 1985 (c) D a v i d P. B e r n a r d , 1985 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. 1 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 <9e/bW ^ f i i " DE-6(3/81) i i ABSTRACT Recent e v i d e n c e s t r o n g l y s u g gests t h a t aluminum t o x i c i t y i s i m p o r t a n t i n d e t e r m i n i n g the s t r u c t u r a l and f u n c t i o n a l c h a r a c t e r i s t i c s of f r e s h w a t e r communities a f f e c t e d by a c i d p r e c i p i t a t i o n . To d e t e r m i n e the e f f e c t d i s s o l v e d aluminum has on l o t i c i n v e r t e b r a t e s p r e v i o u s l y unexposed t o a n t h r o p o g e n i c a c i d i f i c a t i o n , e x p e r i m e n t s were c a r r i e d out i n a second-order headwater stream 50 km e a s t of Vancouver, B r i t i s h Columbia d u r i n g August 1982. In t h r e e s e p a r a t e e x p e r i m e n t s , HC1 and/or A1C1 3 were added t o M a y f l y Creek d u r i n g d a y l i g h t h o u r s , i n c r e a s i n g a c i d i t y from pH 6.9 - 7.0 t o pH 5.8 - 6.0 and t o t a l aluminum from < 0.1 mg/L t o > 1.0 mg/L. B i o l o g i c a l response was m o n i t o r e d by s a m p l i n g i n v e r t e b r a t e d r i f t w i t h 86 Mm n e t s . R e l a t i v e t o an u n m a n i p u l a t e d , upstream c o n t r o l s i t e , d r i f t d e n s i t y d o u b l e d i n response t o added H + a l o n e (pH 5.9). When A l 3 + was added (pH 5.9) d r i f t d e n s i t y i n c r e a s e d f o u r f o l d . F o l l o w i n g 48 h c o n t i n u o u s d o s i n g w i t h HC1 (pH 5.9) t h e r e was an even g r e a t e r response t o added A l 3 + . Ephemeroptera were a b l e t o d e t e c t d i s s o l v e d aluminum and responded almost i m m e d i a t e l y ( w i t h i n 45 m i n ) . S i m i l a r l y , T r i c h o p t e r a and Chironomidae d e t e c t e d i n c r e a s e d H + c o n c e n t r a t i o n s and responded i m m e d i a t e l y . Response t o augmented A l 3 + by T r i c h o p t e r a , H y d r a c a r i n a , and Chironomidae was d e l a y e d 6 h. However, p r e - e x p o s i n g a n i m a l s t o 48 h HC1 r e s u l t e d i n enhanced aluminum s e n s i t i v i t y f o r Chironomidae and f o r S i m u lium and P l e c o p t e r a , which had not responded w i t h i n 10 h t o H + or A l 3 + a l o n e . I t i s proposed t h a t r a p i d i n c r e a s e s i n d r i f t d e n s i t y a r e due t o b e h a v i o r a l escape r e s p o n s e s , w h i l e d e l a y e d r esponses are p r o b a b l y a s s o c i a t e d w i t h p h y s i o l o g i c a l impairment. E v i d e n c e was a l s o o b t a i n e d s u g g e s t i n g t h a t d u r i n g e a r l y s t a g e s of m o r p h o l o g i c a l development Ephemeroptera and Chironomidae are more s e n s i t i v e t o i n c r e a s e d A l 3 + and H + c o n c e n t r a t i o n s than d u r i n g l a t e r d e v e l o p m e n t a l s t a g e s . In l a b o r a t o r y e x periments u s i n g a r t i f i c i a l stream c h a n n e l s , Chironomidae l a r v a e and Ephemeroptera nymphs were exposed t o C I " and H + c o n c e n t r a t i o n s , e q u a l t o t h o s e d u r i n g f i e l d e x p e r i m e n t s . R e s u l t s showed t h a t d r i f t b e h a v i o r i n the s e a n i m a l s i s not s t i m u l a t e d by m i l d l y e l e v a t e d c h l o r i d e c o n c e n t r a t i o n s . These s t u d i e s demonstrate t h a t i n c r e a s e d d i s s o l v e d aluminum c o n c e n t r a t i o n s i n t e n s i f y b i o l o g i c a l response t o a c i d i f i c a t i o n , and c o n f i r m a c i d s e n s i t i v i t y p a t t e r n s f o r Ephemeroptera and Chironomidae r e p o r t e d by o t h e r s . The observed a c i d i n s e n s i t i v i t y of P l e c o p t e r a , s i m u l i i d s , and T r i c h o p t e r a a l s o conforms t o p r e v i o u s l y d e s c r i b e d p a t t e r n s . E x p e r i m e n t a l l y m a n i p u l a t i n g t h i s community produced r e s u l t s c l o s e l y r e s e m b l i n g those o b t a i n e d i n s i m i l a r s t u d i e s f o r a r e a s c u r r e n t l y a f f e c t e d by a c i d p r e c i p i t a t i o n . The major d i f f e r e n c e i n r e s u l t s between s t u d i e s i s t h a t i n v e r t e b r a t e communities p r e v i o u s l y unexposed t o a c i d i f i c a t i o n c o n t a i n more s p e c i e s s e n s i t i v e t o m i l d a c i d i f i c a t i o n . These l a t t e r a n i m a l s a r e p a r t i c u l a r l y s e n s i t i v e t o the presence of e l e v a t e d d i s s o l v e d aluminum c o n c e n t r a t i o n s . i v TABLE OF CONTENTS ABSTRACT i i LIST OF TABLES v i i LIST OF FIGURES v i i i ACKNOWLEDGEMENTS i x Chapter 1. I n t r o d u c t i o n 1 1 . 1 Background 1 1.2 Problem d e f i n i t i o n 3 1.3 T h e s i s o r g a n i z a t i o n 9 Chapter 2. Methods, M a t e r i a l s and E x p e r i m e n t a l D e s i g n 11 2.1 O b j e c t i v e s and scope 11 2.2 F i e l d - s t u d y s i t e 12 2.3 E x p e r i m e n t a l d e s i g n 15 2.3.1 Background s t u d i e s 19 2.3.2 F i e l d e x p e r i m e n t s 19 2.3.3 L a b o r a t o r y e x p e r i m e n t s 21 2.4 Methods and M a t e r i a l s 22 2.4.1 F i e l d E x periments 22 2.4.1.1 D r i f t sampling 23 2.4.1.2 P h y s i c a l measurements 24 2.4.1.3 C h e m i c a l s a m p l i n g 24 2.4.1.4 Data a n a l y s i s 26 2.4.2 L a b o r a t o r y E x p e r i m e n t s 26 2.4.2.1 B i o l o g i c a l 27 2.4.2.2 P h y s i c a l - c h e m i c a l 28 V 2.4.2.3 Data a n a l y s i s 28 Chapter 3. R e s u l t s of F i e l d and L a b o r a t o r y E x p e r i m e n t s .... 29 3.1 R e s u l t s of f i e l d e x p e r i m e n t s 29 3.1.1 Experiment 1: E f f e c t s of A l 3 + 29 3.1.1.1 B i o l o g i c a l response ... 29 3.1.1.2 P h y s i c a l - c h e m i c a l c o n d i t i o n s 37 3.1.2 Experiment 2: E f f e c t s of H + 40 3.1.2.1 B i o l o g i c a l response 40 3.1.2.2 P h y s i c a l - c h e m i c a l c o n d i t i o n s 47 3.1.3 Experiment 3: A1C1 3 f o l l o w i n g HC1 47 3.1.3.1 B i o l o g i c a l response 49 3.1.3.2 P h y s i c a l - c h e m i c a l c o n d i t i o n s 56 3.2 R e s u l t s of L a b o r a t o r y Experiments w i t h C l " 56 3.2.1 P h y s i c a l - c h e m i c a l c o n d i t i o n s 58 3.2.2 B i o l o g i c a l response 58 3.3 Summary 60 Chapter 4. G e n e r a l D i s c u s s i o n 63 4. 1 B i o t a 63 4.1.1 E v a l u a t i o n of hypotheses 63 4.1.2 B e h a v i o r a l response r a t e s 67 4.1.3 Community/ecosystem i m p l i c a t i o n s 74 4.2 P h y s i c a l - c h e m i c a l 77 4.3 Methods e v a l u a t i o n 79 Chapter 5. C o n c l u s i o n s and Recommendations 81 5.1 C o n c l u s i o n s 81 5.2 S i g n i f i c a n c e 83 5.3 Recommendations f o r F u t u r e Research 86 v i R e f e r e n c e s C i t e d 88 Appendix A. Study S i t e : D e t a i l e d D e s c r i p t i o n 100 Appendix B. E x p e r i m e n t a l F i e l d Methods: D e s i g n , C o n s t r u c t i o n and A p p l i c a t i o n 108 Appendix C. E x p e r i m e n t a l L a b o r a t o r y Methods: D e s i g n , C o n s t r u c t i o n and A p p l i c a t i o n 112 Appendix D. A n a l y t i c a l Methods 117 LIST OF TABLES v i i Ta b l e 2.1 Hypotheses t e s t e d i n f i e l d and l a b o r a t o r y e x p e r i m e n t s 15 Tab l e 2.2 Parameters Measured i n F i e l d E x periments 22 T a b l e 2.3 C h l o r i d e E x p e r i m e n t : Test c o n d i t i o n s 27 T a b l e 3.1 D r i f t response t o A l 3 + 32 Tab l e 3.2 Water C h e m i s t r y : Experiment 1 39 Tab l e 3.3 D r i f t response t o H* 42 Tab l e 3.4 Water C h e m i s t r y : Experiment 2 48 Tab l e 3.5 D r i f t response t o A1C1 3 f o l l o w i n g HC1 51 Tab l e 3.6 Water c h e m i s t r y : C h l o r i d e E xperiments 58 Tab l e D.1 Water volume f i l t e r e d : C o n v e r s i o n f a c t o r s 120 v i i i LIST OF FIGURES F i g u r e 2.1 M a y f l y Creek: G e o g r a p h i c a l l o c a t i o n 13 F i g u r e 2.2 M a y f l y Creek: Study s i t e d e t a i l 16 F i g u r e 3.1 T o t a l d r i f t r e s p o n s e : E x p t . 1 30 F i g u r e 3.2 Ephemeroptera response: E x p t . 1 33 F i g u r e 3.3 C h i r o n o m i d r e s p o n s e : Expt.1 35 F i g u r e 3.4 T r i c h o p t e r a and H y d r a c a r i n a response: E x p t . 1 . . 3 6 F i g u r e 3.5 M a y f l y Creek D i s c h a r g e : August, 1'982 38 F i g u r e 3.6 T o t a l d r i f t r e s p o n s e : E x p t . 2 41 F i g u r e 3.7 Ephemeroptera response: E x p t . 2 43 F i g u r e 3.8 C h i r o n o m i d r e s p o n s e : E x p t . 2 45 F i g u r e 3.9 T r i c h o p t e r a and Simulium r e s p o n s e : E x p t . 2 '46 F i g u r e 3.10 T o t a l and Ephemeroptera D r i f t r e s p o n s e : E x p t . 3 50 F i g u r e 3.11 Chironomidae and T r i c h o p t e r a D r i f t r e s p onse: E x p t . 3 52 F i g u r e 3.12 H y d r a c a r i n a and H a r p a c t a c o i d a D r i f t r e s p onse: E x p t . 3 55 F i g u r e 3.13 Simulium and P l e c o p t e r a r e s p o n s e : E x p t . 3 57 F i g u r e A.1 D i e l d r i f t p a t t e r n s a t M a y f l y Creek 104 F i g u r e C.1 T e s t i n g a p p a r a t u s : Schematic diagram 113 i x ACKNOWLEDGEMENTS I t i s u t t e r l y i m p o s s i b l e f o r one person t o e n t e r i n t o modern s c i e n c e a l o n e , never mind make a c o n t r i b u t i o n , f o r s c i e n c e i s l i k e a c o n v e r s a t i o n ; w i t h o u t knowing what has been s a i d p r i o r t o a r r i v i n g on the scene we a r e unable t o engage i n m e a n i n g f u l d i s c u s s i o n . To a l l th o s e p e o p l e who g e n e r o u s l y shared t h e i r knowledge, time and wisdom w i t h me, thank you. S p e c i f i c r e c o g n i t i o n i s due the members of my r e s e a r c h committee, D r s . W i l l i a m E. N e i l l , Tom G. N o r t h c o t e and Ken H a l l , f o r t h e i r p a t i e n c e , u n d e r s t a n d i n g , and comments on t h i s t h e s i s . The m a n u s c r i p t was a l s o s u b s t a n t i a l l y improved by comments r e c e i v e d from Dr. J . S c o t t C a r l e y , John R i c h a r d s o n , and Brad A n h o l t . Use of E n v i r o n m e n t a l E n g i n e e r i n g L a b o r a t o r y f a c i l i t i e s was ar r a n g e d by Dr. H a l l . I would a l s o l i k e t o thank Dr. M. Quick f o r l o a n i n g h y d r o l o g y equipment and p r o v i d i n g e s s e n t i a l plumbing a d v i c e . M a t e r i a l s f o r t h i s p r o j e c t were donated by Texada Lime, S t e e l B r o t h e r s (Lime D i v i s i o n ) , Ocean E n g i n e e r i n g , and G u l f O i l . E a r l y i n t h i s p r o j e c t , Dr. M. F e l l e r u n s e l f i s h l y shared both h i s time and p r e c i p i t a t i o n c h e m i s t r y d a t a w i t h me. S p e c i a l computing a s s i s t a n c e was p r o v i d e d by A. B l a c h f o r d and S. E r t i s , of the U.B.C. B i o s c i e n c e s Data C e n t e r . J . R i c h a r d s o n g e n e r o u s l y p r o v i d e d the l i s t of s p e c i e s i d e n t i f i e d from M a y f l y Creek. Many i n d i v i d u a l s c o n t r i b u t e d a s s i s t a n c e - i n f i e l d w o r k i n c l u d i n g : B i l l N e i l l , W i l l i a m Chan, P e t e r Saunders and h i s crew X a t the U.B.C. Res e a r c h F o r e s t , and Nancy Rogers. I would a l s o l i k e t o e s p e c i a l l y thank S c o t t C a r l e y , John R i c h a r d s o n , and Tom S a k a t a f o r t h e i r moral s u p p o r t , w i t h o u t which t h i s t h e s i s might w e l l have become p a r t of f o l k l o r e , r a t h e r than w r i t t e n h i s t o r y . I t g i v e s me g r e a t p l e a s u r e t o acknowledge my SUPERvisor Dr. W i l l i a m E. N e i l l , and t o p u b l i c a l l y commend him f o r h i s good judgement, wisdom, g e n e r o s i t y , humor and most of a l l , tremendous humanity. I t i s a w o n d e r f u l e x p e r i e n c e t o meet an e d u c a t o r who i s b o t h a good s c i e n t i s t and an o u t s t a n d i n g h u m a n i t a r i a n . B i l l , however, i s one such i n d i v i d u a l . F i n a l l y , a v e r y s p e c i a l thanks goes t o A. C h r i s t i n e H j o r l e i f s o n . Her " c a r r o t s " , encouragement, and l o v e kept me moving d u r i n g those t i m e s when the wind seemed t o have d i e d and the ebb t i d e t h r e a t e n e d t o h a l t my p r o g r e s s a l l t o g e t h e r . F i n a n c i a l s u p p o r t f o r t h i s r e s e a r c h came from an NSERC o p e r a t i n g g r a n t t o Dr. W. E. N e i l l . T e a c h i n g a s s i s t a n t s h i p s from the Zoology Department, and summer r e s e a r c h a s s i s t a n t s h i p s from B.C. y o u t h employment programs p r o v i d e d n e c e s s a r y p e r s o n a l f i n a n c i a l s u p p o r t . 1 CHAPTER 1. INTRODUCTION J_._1_ Background A c i d p r e c i p i t a t i o n i s n e i t h e r new nor u n n a t u r a l . Chemical a n a l y s e s of i c e d e p o s i t s a t b o t h p o l e s have p r o v i d e d good e v i d e n c e t h a t f o r a t l e a s t the pa s t 10,000 y e a r s p r e c i p i t a t i o n f a l l i n g i n the s e r e g i o n s has been a c i d i c (pH < 6) (Delmas and Gra v e n h o r s t 1983). C u r r e n t l y , i n many remote a r e a s of the p l a n e t , background p r e c i p i t a t i o n a c i d i t y i s a l s o below pH 6 (Galloway et a l . 1982). S i n c e pure water has a pH of 7, i t seems c l e a r t h a t n a t u r a l f a c t o r s have been c o n t r i b u t i n g t o at m o s p h e r i c p r e c i p i t a t i o n a c i d i t y f o r m i l l e n n i a . The c h e m i s t r y of at m o s p h e r i c water vapor i s a f f e c t e d by the presence of n a t u r a l t r a c e gases ( e . g . C 0 2 , S 0 2 , NOx, NH 3) most of which cause a l o w e r i n g of pH when absorbed ( C h a r l s o n and Rodhe 1982). For example, water i n e q u i l i b r i u m w i t h atmospheric C0 2 (330 ppm volume) w i l l have a pH of 5.6 due t o the f o r m a t i o n of c a r b o n i c a c i d . However, r e a c t i o n s i n v o l v i n g s u l f u r and n i t r o g e n dominate the c h e m i s t r y of a t m o s p h e r i c water (Junge 1972; C h a r l s o n and Rodhe 1982); c o n s e q u e n t l y , even s m a l l i n c r e a s e s i n the c o n c e n t r a t i o n of the s e gases s t r o n g l y a f f e c t s p r e c i p i t a t i o n a c i d i t y , r e s u l t i n g i n pH v a l u e s below 5.6. Long b e f o r e a n t h r o p o g e n i c e m i s s i o n s c o n t r i b u t e d t o the g l o b a l s u l f u r c y c l e , a t m o s p h e r i c s u l f u r o x i d e c o n c e n t r a t i o n s v a r i e d i n response t o , among o t h e r f a c t o r s , e p i s o d i c v o l c a n i c a c t i v i t y . S t u d i e s of G r e e n l a n d i c e c o r e s , f o r example, have r e v e a l e d t h a t major e r u p t i o n s i n the N o r t h e r n Hemisphere 2 p e r i o d i c a l l y l e a d t o i n c r e a s e d S 0 2 c o n c e n t r a t i o n s i n d e p o s i t e d p r e c i p i t a t i o n (Herron et a l . 1977). F o l l o w i n g an e r u p t i o n t h e s e s h i f t s i n S 0 2 c o n c e n t r a t i o n t y p i c a l l y have been accompanied by i n c r e a s e d p r e c i p i t a t i o n a c i d i t y l a s t i n g s e v e r a l y e a r s (Herron e t a l . 1977). Now, a n t h r o p o g e n i c e m i s s i o n s of s u l f u r and n i t r o g e n gases are superimposed upon n a t u r a l , background c o n d i t i o n s w i t h the r e s u l t t h a t d u r i n g the l a s t c e n t u r y s u l f a t e and n i t r a t e c o n c e n t r a t i o n s i n Greenland snow have i n c r e a s e d t h r e e f o l d and t w o f o l d , r e s p e c t i v e l y (Wolff and P e e l 1985). C o n c u r r e n t l y , a c i d i t y measurements of snow d e p o s i t e d i n the Canadian A r c t i c d u r i n g the p a s t q u a r t e r c e n t u r y demonstrate not o n l y a s i g n i f i c a n t d e c r e a s e i n pH (0.007 pH u n i t s per y e a r ) , but a l s o s e a s o n a l v a r i a t i o n i n a c i d i t y w i t h maximum c o n c e n t r a t i o n s a t t a i n e d each s p r i n g (Koerner and F i s h e r 1982). F u n d a m e n t a l l y , a c i d p r e c i p i t a t i o n i s a r a t e problem. Si m p l y s t a t e d , the a c i d i t y of n a t u r a l l y d e p o s i t e d r a i n , snow, fog and o t h e r forms of a t m o s p h e r i c water appears t o be i n c r e a s i n g a t a r a t e t h a t c e r t a i n l o c a l i z e d ecosystems a r e unable t o accommodate. Through e v o l u t i o n , component p o p u l a t i o n s i n these ecosystems have adapted t o p r e v a i l i n g e n v i r o n m e n t a l c o n d i t i o n s d e t e r m i n e d , i n p a r t , by p r e c i p i t a t i o n c h e m i s t r y . To i n d i v i d u a l s l o c a t e d where p r e c i p i t a t i o n c h e m i s t r y i s now c h a n g i n g , the r a t e of change i s p r o b a b l y more im p o r t a n t than the tendency toward d e c r e a s e d pH. Thus, p r e c i p i t a t i o n a c i d i f i c a t i o n , per se, i s p r o b a b l y no more a problem than a l k a l i z a t i o n would be. 3 In most l o c a t i o n s , g l o b a l l y , n e i t h e r i n c r e a s e d c o n c e n t r a t i o n nor d e p o s i t i o n of e i t h e r s u l p h u r or n i t r o g e n per  se i s cause f o r c o n c e r n , and i n many a r i d a r e a s , i n c r e a s e d hydrogen i o n c o n c e n t r a t i o n and d e p o s i t i o n onto s o d i c s o i l s would be welcomed by range managers and a g r i c u l t u r i s t s a l i k e . To un d e r s t a n d the e c o l o g i c a l e f f e c t s a t t e n d a n t w i t h e l e v a t e d a t m o s p h e r i c p r e c i p i t a t i o n a c i d i t y , one must a p p r e c i a t e t h a t t h i s i s b a s i c a l l y an ecosystem problem. Nowhere i s t h i s f a c t more o b v i o u s than i n the case of headwater strea m s . J_.2_ Problem d e f i n i t i o n As a l r e a d y d e s c r i b e d f o r A r c t i c r e g i o n s , changes i n at m o s p h e r i c c h e m i s t r y can a f f e c t the i o n i c c o m p o s i t i o n of snow. In temperate zones, w i n t e r snow a c c u m u l a t i o n r e p r e s e n t s a temporary s t o r a g e of water and a s s o c i a t e d a c i d s w hich, from the p e r s p e c t i v e of stream ecosystems, r e s u l t s i n e p i s o d i c a c i d i f i c a t i o n each s p r i n g . A c i d i f i c a t i o n of r u n n i n g w a t e r s d u r i n g s p r i n g r u n o f f was commented on by Dannevig (1959) f o r s e v e r a l c o a s t a l streams i n so u t h e r n Norway. S u b s e q u e n t l y , pH d e p r e s s i o n d u r i n g snowmelt has now been documented f o r many o t h e r streams and r i v e r s i n Norway, as w e l l as Sweden, F i n l a n d , O n t a r i o , and the n o r t h e a s t e r n U n i t e d S t a t e s (Galloway 1983). In t h e s e a r e a s the e a r l i e s t p o r t i o n of the s p r i n g r u n o f f can be even more a c i d i c t han e x p e c t e d based upon c h e m i c a l a n a l y s i s of the accumulated snow pack. Hornbeck et a l . (1977) n o t e d t h a t the most a c i d i c w a t e r s were produced d u r i n g the e a r l y s t a g e s of snowmelt and 4 S e i p (1980b) r e p o r t e d t h a t t y p i c a l l y 50 t o 80% of the p o l l u t a n t s i n snow are f l u s h e d out w i t h the f i r s t 30% of the snowmelt. E p i s o d i c a c i d i f i c a t i o n of headwater streams can e l e v a t e a c i d i t y more than one o r d e r of magnitude; c o n c o m i t a n t l y , a l k a l i n i t y may drop t h r e e o r d e r s of magnitude or more (Galloway 1983). O b s e r v a t i o n s d u r i n g snowmelt by r e s e a r c h e r s i n S w i t z e r l a n d , M i n n e s o t a , O n t a r i o , and New York have shown t h a t stream water a l k a l i n i t y v a l u e s r i s e s u b s t a n t i a l l y as one moves downstream (Marmorek e t a l . 1984). Presumably reduced a l k a l i n i t y i n headwater reaches i s caused by a v a r i e t y of f a c t o r s i n c l u d i n g a c i d i f i c a t i o n per se and by m i n i m a l s o i l c o n t a c t between melt waters and the upper watershed. C o n s e q u e n t l y , even streams w i t h pH > 6.5 may p e r i o d i c a l l y be r a p i d l y a c i d i f i e d t o pH < 5.0 (Gal l o w a y 1983). R a p i d but s h o r t -term d e p r e s s i o n s i n pH, such as those d u r i n g s p r i n g r u n o f f , may be d i s p r o p o r t i o n a t e l y i m p o r t a n t i n d e t e r m i n i n g the b i o l o g i c a l consequences of stream a c i d i f i c a t i o n . E p i s o d i c e l e v a t i o n of stream a c i d i t y (> 1 pH u n i t ) has a l s o been shown t o r e s u l t from v o l c a n i c e r u p t i o n s (Kurenkov 1958) and, i n r a r e i n s t a n c e s , heavy r a i n f a l l e v e n t s ( S c h e i d e r e t a l . 1979), but t h e s e a r e u n u s u a l c i r c u m s t a n c e s . N o r m a l l y , n a t u r a l f l u c t u a t i o n s i n H + i o n c o n c e n t r a t i o n s over the c o u r s e of 12 months remain w i t h i n 1 pH u n i t i n headwater streams ( L i k e n s e t a l . 1977; F e l l e r and Kimmins 1979). D u r i n g autumn, streams i n decid u o u s f o r e s t s may a l s o t e m p o r a r i l y e x p e r i e n c e i n c r e a s e d a c i d i t y as a r e s u l t of l e a f l i t t e r d e c o m p o s i t i o n ( S l a c k and F e l t z 1968). 5 H i s t o r i c a l l y , many stream e c o l o g i s t s i m p l i c i t l y assumed t h a t water c h e m i s t r y remains r e l a t i v e l y c o n s t a n t t h r o u g h t i m e , at l e a s t on the s c a l e of i n s e c t l i f e h i s t o r i e s . Now, however, i n some l o t i c h a b i t a t s f a c t o r s a r e r a p i d l y a l t e r i n g water c h e m i s t r y and stream e c o l o g i s t s c l e a r l y must be a l e r t t o t h i s p o s s i b i l i t y , even i n seemingly remote a r e a s . Streams e n t i r e l y f r e e of p o l l u t i o n are i n c r e a s i n g l y r a r e and i n many areas may no l o n g e r e x i s t . R e t r o s p e c t i v e e x a m i n a t i o n of p u b l i s h e d l i t e r a t u r e p e r t a i n i n g t o the r e l a t i o n s h i p between i o n i c c o m p o s i t i o n of r u n n i n g waters and the c o m p o s i t i o n of l o t i c i n v e r t e b r a t e communities r e v e a l s u n c e r t a i n t y c o n c e r n i n g the s i g n i f i c a n c e of c h e m i c a l f a c t o r s i n a f f e c t i n g the d i s t r i b u t i o n , abundance, and p e r s i s t e n c e of l o t i c (stream d w e l l i n g ) a n i m a l s . In h i s c l a s s i c r eview of stream e c o l o g y , Hynes (1970) l i s t e d the f o l l o w i n g c h e m i c a l f a c t o r s as i m p o r t a n t i n n a t u r a l f r e s h w a t e r s f o r t h e i r e f f e c t on b e n t h i c i n v e r t e b r a t e communities: oxygen, s a l i n i t y , a c i d i t y , and hardness. He c o n c l u d e d t h a t , e xcept i n unusual cases or p o l l u t e d w a t e r s , d i s s o l v e d oxygen and s a l i n i t y a r e r a r e l y of major s i g n i f i c a n c e , e s p e c i a l l y i n headwater streams. He d i d , however, i n d i c a t e t h a t f o r at l e a s t some s p e c i e s , a c i d i t y and/or hardness a r e i m p o r t a n t but then goes on t o admit t h a t how t h e s e f a c t o r s o p e r a t e i s l a r g e l y unknown. In f a c t , H u t c h i n s o n (1941) came t o the same c o n c l u s i o n 3 decades e a r l i e r , and h i s statement on t h i s t o p i c i s p r o b a b l y s t i l l a c c u r a t e today (pg. 410): " I t i s , however, e x c e e d i n g l y d o u b t f u l i f more than a 6 s i n g l e case has ever been brought f o r w a r d d e m o n s t r a t i n g u n e q u i v o c a l l y t h a t the n a t u r a l v a r i a t i o n i n numbers of any a n i m a l i s due t o pH..." B i o l o g i c a l communities i n headwater r e a c h e s a r e q u i t e d i s t i n c t from those i n h i g h e r o r d e r streams and a t lower e l e v a t i o n s (Hynes 1970; Hawkes 1975). H i s t o r i c a l l y , t h e s e d i f f e r e n c e s were a t t r i b u t e d t o the t r a d i t i o n a l l y r e c o g n i z e d v a r i a b l e s - - t e m p e r a t u r e , f l o w , s u b s t r a t e , o r d i s s o l v e d oxygen c o n t e n t . However, i n 1969 M i n s h a l l and Kuehne a t t r i b u t e d b e n t h i c d i f f e r e n c e s i n the upper and l o w e r R i v e r Duddon t o c h e m i c a l f a c t o r s . W h i l e c o n f i r m i n g the o b s e r v e d r e l a t i o n s h i p between stream water c h e m i s t r y and b e n t h i c f a u n a l c o m p o s i t i o n , S u t c l i f f e and C a r r i c k (1973) p o s t u l a t e d t h a t pH was e x e r t i n g an i n f l u e n c e i n d i r e c t l y by a l t e r i n g f o o d s u p p l y . No doubt the w e l l , e s t a b l i s h e d f a c t t h a t c h e m i c a l f a c t o r s i n f l u e n c e d i s t r i b u t i o n of a q u a t i c a l g a e a f f e c t e d t h i s c o n c l u s i o n . C o u n t e r i n g w i t h e x p e r i m e n t a l t e s t s , M i n s h a l l and M i n s h a l l (1978) then showed c h e m i c a l f a c t o r s i n the R i v e r Duddon can d i r e c t l y l i m i t i n v e r t e b r a t e d i s t r i b u t i o n . N o n e t h e l e s s , d e s p i t e the s t r o n g c o r r e l a t i o n between pH and i n v e r t e b r a t e community c o m p o s i t i o n , the M i n s h a l l s r e j e c t e d the c o n c l u s i o n t h a t v a r i a t i o n s i n hydrogen i o n c o n t e n t were p r i m a r i l y r e s p o n s i b l e f o r c o n t r o l l i n g d i s t r i b u t i o n of i n v e r t e b r a t e s i n the R i v e r Duddon and suggested t h a t some o t h e r ( u n i d e n t i f i e d ) c h e m i c a l f a c t o r ( s ) was o p e r a t i n g i n t h i s system. A major geochemical consequence- of a c i d p r e c i p i t a t i o n i s the r e l e a s e of aluminum i o n s i n t o groundwater, streams, r i v e r s 7 and l a k e s . Aluminum m o b i l i z a t i o n has been documented i n S c a n d i n a v i a ( D i c k s o n 1980; S e i p 1980a; S e i p et a l . 1984), Wales .(Stoner e t a l . 1984), e a s t e r n Canada (Campbell et a l . 1984), and the n o r t h e a s t e r n U.S.A. (Johnson e t a l . 1981; D r i s c o l l e t a l . 1983). In each case aluminum l i b e r a t i o n i s a t t r i b u t e d t o watershed a c i d i f i c a t i o n . A n t h r o p o g e n i c a l l y - d e r i v e d a c i d s a r e " n e u t r a l i z e d " by c a t i o n exchange r e a c t i o n s w i t h s o i l s (N.M. Johnson 1979) or stream and l a k e benthos (Hooper e t a l . 1985; H a l l et a l . 1985b). These r e a c t i o n s l i b e r a t e d i s s o l v e d aluminum i o n s , p r e v i o u s l y i m m o b i l i z e d on a n i o n i c o r g a n i c and i n o r g a n i c s u r f a c e s . Thus, c a t i o n exchange r e a c t i o n s can r e s u l t i n a m p l i f c a t i o n of the e c o l o g i c a l e f f e c t s of i n c r e a s e d H + d e p o s i t i o n t h rough l i b e r a t i o n of o t h e r c a t i o n s w i t h p o t e n t i a l l y h i g h e r t o x i c i t y . In l a b o r a t o r y b i o a s s a y s , aluminum has been shown t o be t o x i c t o f r e s h w a t e r i n v e r t e b r a t e s i n c l u d i n g a r t h r o p o d s ( B i e s i n g e r and C h r i s t e n s e n , 1972), p l a n a r i a (Jones, 1940), b a c t e r i a , f u n g i , and a l g a e (Burrows, 1977). More r e c e n t e v i d e n c e has suggested t h a t aluminum t o x i c i t y i n f l u e n c e s the s t r u c t u r e and f u n c t i o n a l c h a r a c t e r i s t i c s of f r e s h w a t e r i n v e r t e b r a t e communities a f f e c t e d by a c i d i c p r e c i p i t a t i o n (Haines 1981; NRCC 1981; NAS 1981). Changes i n abundance of a q u a t i c i n s e c t s ( H a l l e t a l . 1980, 1982, 1985b; Herrmann and Baron 1980) and o l i g o c h a e t e s (Raddum 1980) i n a c i d i c w a t e r s have been a t t r i b u t e d t o the c o n c e n t r a t i o n of aluminum. S i n c e e l e v a t e d aluminum c o n c e n t r a t i o n s have been found i n a c i d i f y i n g headwater streams i n Sweden, Norway, S c o t l a n d , 8 B e l g i u m , the U n i t e d S t a t e s and Canada ( D r i s c o l l 1983), i t i s e s s e n t i a l t h a t the r e l a t i v e importance of H + and A l 3 + i o n s i n c a u s i n g o b s e r v e d changes i n l o t i c communities be i n v e s t i g a t e d . In 1977, H a l l e t a l . (1980) e x p e r i m e n t a l l y lowered the pH of N o r r i s Brook, a mountain stream i n the Hubbard Brook E x p e r i m e n t a l F o r e s t of New Hampshire, from pH 5.4-6.4 t o pH 3.9-4.2 f o r 5 months by adding s u l f u r i c a c i d . For the f i r s t week, e l e v a t e d a c i d i t y r e s u l t e d i n i n c r e a s e d d r i f t a c t i v i t y of l a r g e i n v e r t e b r a t e s ; t h e r e a f t e r , no d i f f e r e n c e was d e t e c t e d i n d r i f t between c o n t r o l and e x p e r i m e n t a l a r e a s . D u r i n g the p e r i o d when d r i f t d e n s i t y was e l e v a t e d , t h e r e was a l s o a s i g n i f i c a n t i n c r e a s e i n d i s s o l v e d aluminum c o n c e n t r a t i o n . C o n s e q u e n t l y , i t i s i m p o s s i b l e t o d i s t i n g u i s h e f f e c t s due t o i n c r e a s e d H + from tho s e r e s u l t i n g from e l e v a t e d A l 3 + i o n c o n c e n t r a t i o n s . Because t h e r e was a p r i o r h i s t o r y of a c i d i f i c a t i o n a t t h i s s i t e , i t i s a l s o l i k e l y t h a t many of the most s e n s i t i v e i n v e r t e b r a t e s p e c i e s had been e x c l u d e d from the community even b e f o r e the experiment began. The r e s e a r c h r e p o r t e d on here was d e s i g n e d t o examine responses by b e n t h i c i n v e r t e b r a t e s from a community r e l a t i v e l y n a i v e t o a c i d i f i c a t i o n , t o r a p i d , but n o n - l e t h a l i n c r e a s e s i n H + and A l 3 + , s e p a r a t e l y and i n c o m b i n a t i o n . The g e n e r a l q u e s t i o n here i s what e f f e c t does d i s s o l v e d aluminum have on stream i n v e r t e b r a t e s under c o n d i t i o n s of m i l d a c i d i f i c a t i o n ? 9 J_._3 T h e s i s o r g a n i z a t i o n In Chapter 2 I o u t l i n e my o v e r a l l e x p e r i m e n t a l d e s i g n used to t e s t s e v e r a l hypotheses u s i n g f i e l d and l a b o r a t o r y e x p e r i m e n t s . F i v e s e p a r a t e , but r e l a t e d , e x p e r i m e n t s were used i n t h i s r e s e a r c h program. Methods and m a t e r i a l s a r e a l s o b r i e f l y d e s c r i b e d i n Chapter 2. D e t a i l s of the a n a l y t i c a l methods employed a r e p r o v i d e d i n Appendix D. R e s u l t s of the t h r e e f i e l d e x p e r i m e n t s , d e a l i n g w i t h r e l a t i v e s e n s i t i v i t y of stream i n v e r t e b r a t e s t o H + and A l 3 + i o n s are d e s c r i b e d i n the f i r s t p a r t of Chapter 3_. R e s u l t s of the two l a b o r a t o r y e x p e r i m e n t s , t e s t i n g responses of c h i r o n o m i d and Ephemeroptera l a r v a e t o e l e v a t e d c h l o r i d e i o n c o n c e n t r a t i o n s are d e t a i l e d i n the l a t t e r p a r t of Chapter 3. G e n e r a l d i s c u s s i o n of the e x p e r i m e n t a l r e s u l t s forms Chapter 4_. Here the hypotheses a r e e v a l u a t e d i n l i g h t of e x p e r i m e n t a l r e s u l t s . C o n c l u s i o n s have been r e s e r v e d f o r Chapter 5_, where the s i g n i f i c a n c e of t h i s r e s e a r c h i s reviewed from a l a r g e r p e r s p e c t i v e . Recommendations f o r f u t u r e r e s e a r c h are a l s o o f f e r e d a t the end of t h i s c h a p t e r . When t h i s r e s e a r c h program was i n i t i a t e d , t h e r e were no p u b l i s h e d r e p o r t s of s i m i l a r f i e l d e x p e r i m e n t s i n v o l v i n g aluminum i n the l i t e r a t u r e . C o n s e q u e n t l y , c o n s i d e r a b l e time and e f f o r t were devo t e d t o d e v e l o p i n g new t e c h n i q u e s and a p p a r a t u s . D e t a i l s and d e s c r i p t i o n s of methods employed i n the f i e l d e x p e r i m e n t s a r e p r o v i d e d i n Appendix B. As w e l l , Appendix A c o n t a i n s a d e t a i l e d d e s c r i p t i o n of the study s i t e and f i e l d s t a t i o n t h a t I c o n s t r u c t e d a t M a y f l y Creek. In a d d i t i o n t o 10 d e s i g n i n g and c o n s t r u c t i n g b r i d g e s , p l a t f o r m s , e l e c t r i c a l g e n e r a t i n g f a c i l i t i e s and o t h e r support s t r u c t u r e s e s s e n t i a l t o the f i e l d e x p e r i m e n t s , I d e s i g n e d and b u i l t 15 a r t i f i c i a l stream c h a n n e l s , which a r e d e t a i l e d i n Appendix C. 11 CHAPTER 2. METHODS, MATERIALS AND EXPERIMENTAL DESIGN 2_.J_ O b j e c t i v e s and scope T h i s r e s e a r c h was d e s i g n e d t o t e s t the f o l l o w i n g hypotheses u s i n g f i e l d and l a b o r a t o r y e x p e r i m e n t s : (1) Some l o t i c i n v e r t e b r a t e s r e s i d i n g i n g e o c h e m i c a l l y s e n s i t i v e a r e a s of B.C. can d e t e c t and respond t o d i s s o l v e d aluminum i o n s . (2) Not a l l taxonomic groups respond s i m i l a r l y t o e l e v a t e d d i s s o l v e d aluminum c o n c e n t r a t i o n s . ( 3 ) Some l o t i c i n v e r t e b r a t e s a r e r e l a t i v e l y more s e n s i t i v e t o aluminum than t o hydrogen i o n s . ( 4 ) For " s e n s i t i v e " i n v e r t e b r a t e s , e a r l y i n s t a r s a r e more s e n s i t i v e t o i n c r e a s e d A l 3 + and H + i o n c o n c e n t r a t i o n s than are l a t e r i n s t a r s . To t e s t these hypotheses I used j^n s i t u e x p e r i m e n t s augmenting aluminum and hydrogen i o n c o n c e n t r a t i o n s . S e v e r a l advantages a c c r u e by c o n d u c t i n g _in s i t u e x p e r i m e n t s i n a n a t u r a l headwater stream of the Coast Range Mountains of B r i t i s h C o l umbia. (1) U n l i k e streams i n e a s t e r n N o r t h A m e r i c a , t h e r e i s no p r e v i o u s h i s t o r y of a n t h r o p o g e n i c a c i d i f i c a t i o n problems h e r e ; t h u s , b e n t h i c communities a t t h i s s i t e a r e r e l a t i v e l y n a i v e , v i s a v i s a c i d i f i c a t i o n . C o n s e q u e n t l y , " s e n s i t i v e " s p e c i e s a r e s t i l l p r e s e n t . (2) By e x p o s i n g p o r t i o n s of ecosystems t o c o n t r o l l e d p e r t u r b a t i o n s , one can overcome d e f i c i e n c i e s i n h e r e n t i n l a b o r a t o r y b i o a s s a y s i n c l u d i n g (a) f a i l u r e t o d u p l i c a t e c r i t i c a l sediment/water i n t e r a c t i o n s ( e.g. 1 2 sedimentary aluminum r e l e a s e v i a c a t i o n exchange r e a c t i o n s ) , (b) i n a b i l i t y t o s i m u l t a n e o u s l y expose e n t i r e n a t u r a l b i o t i c assemblages, and (c) t e c h n i c a l problems i n m a i n t a i n i n g water c u r r e n t f l o w i n g over the g i l l s of r h e o p h i l i c i n s e c t s . (3) Headwater streams i n the Coast Range Mountains would be prime c a n d i d a t e s f o r aluminum "problems" i f these watersheds were exposed t o a t m o s p h e r i c a c i d s because p o d z o l i c s o i l s here ( K l i n k a and Lowe 1975; V a l e n t i n e and L a v k u l i c h 1978) (a) have a h i g h aluminum c o n t e n t , (b) e x h i b i t a r e l a t i v e l y low c a t i o n exchange c a p a c i t y , (c) a r e t h i n and f r e e of c a r b o n a t e s , (d) a r e a c i d i c (pH < 4 ) , and (e) are low i n base s a t u r a t i o n . Under these c o n d i t i o n s , b u f f e r i n g c a p a c i t y i n s o i l s and stream sediments would be d e t e r m i n e d p r i m a r i l y by c h e m i c a l r e a c t i o n s t h a t r e l e a s e aluminum and o t h e r c a t i o n s . (4) F i n a l l y , the e n t i r e Coast Mountain Range of B r i t i s h Columbia i s known t o be g e o l o g i c a l l y s u s c e p t i b l e t o a c i d i f i c a t i o n ( G alloway and C o w l i n g 1978; C l a r k and Bonham 1982). 2.2 F i e l d - s t u d y s i t e M a y f l y Creek (50 km e a s t of Vancouver) i n the U.B.C. Research F o r e s t was s e l e c t e d as the l o c a t i o n f o r f i e l d s t u d i e s ( F i g . 2.1). The watershed f o r t h i s second-order stream l i e s between 315 and 760 m A.S.L. Because of h i g h a n n u a l r a i n f a l l (>200 cm), s t e e p s l o p e s , and t h i n s o i l s c o n t a i n i n g macrochannels ( F e l l e r and Kimmins 1979), r u n o f f i n t h i s a r e a i s r a p i d . A l t h o u g h no p r e v i o u s s t u d i e s have been p u b l i s h e d documenting d i s c h a r g e p a t t e r n s or water c h e m i s t r y f o r M a y f l y Creek, STUDY SITE LOCATION metres F i g u r e 2.1 M a y f l y Creek: G e o g r a p h i c a l l o c a t i o n 1 4 e x t e n s i v e d a t a are a v a i l a b l e f o r a s i m i l a r stream, E a s t Creek, 5 km t o the southwest. A c c o r d i n g t o F e l l e r and Kimmins (1979), stream d i s c h a r g e i n t h i s area i s t y p i c a l l y h i g h (>1000 L/sec) from October or November u n t i l A p r i l . D u r i n g summer months, flo w i s o f t e n <10 L / s e c , and may remain depressed u n t i l autumn r a i n s b e g i n . At M a y f l y Creek, stream-water temperature v a r i e s from a h i g h of around 20°C to below z e r o i n w i n t e r . D u r i n g the summer, dense b a n k - s i d e v e g e t a t i o n shades the stream, m o d u l a t i n g temperature f l u c t u a t i o n s . C h e m i c a l l y , streams i n t h i s a r e a are c h a r a c t e r i z e d by n e u t r a l t o s l i g h t l y a c i d i c water, w i t h pH u s u a l l y r a n g i n g from 6.5-7.3 ( F e l l e r and Kimmins 1979). In u n d i s t u r b e d w a t e r s h e d s , such as M a y f l y Creek, e l e c t r i c a l c o n d u c t i v i t y of the water i s low (around 20/xS/cm) , and c o n c e n t r a t i o n of most major i o n s ( K + , C a + , Mg +, C I " , and Na +) i s l e s s than 2 mg/L. Maximum v a l u e s f o r most c h e m i c a l parameters are r e c o r d e d d u r i n g l a t e summer and e a r l y autumn, w i t h minimum v a l u e s observed i n w i n t e r and e a r l y s p r i n g . Stream waters here a r e u s u a l l y >90% s a t u r a t e d w i t h d i s s o l v e d oxygen ( F e l l e r and Kimmins 1979). E x p e r i m e n t s were c a r r i e d out on M a y f l y Creek i m m e d i a t e l y above the j u n c t i o n w i t h Jacobs Creek. T h i s p a r t i c u l a r s i t e was i d e a l f o r s e v e r a l reasons i n c l u d i n g : (1) permanent water f l o w , (2) low c o n c e n t r a t i o n of d i s s o l v e d i o n s and o r g a n i c m a t t e r , (3) a d i v e r s e , w e l l d e v e l o p e d a q u a t i c i n s e c t community, (4) easy a c c e s s i b i l i t y , (5) m i n i m a l exposure t o v a n d a l i s m , and (6) presence of an i s l a n d . The i s l a n d s e p a r a t e s M a y f l y Creek i n t o two a d j a c e n t c h a n n e l s ( F i g . 2.2) w i t h n e a r l y i d e n t i c a l 15 water c h e m i s t r y and b e n t h i c communities. T h i s s e p a r a t i o n made i t p o s s i b l e t o r e f i n e e x p e r i m e n t a l t e c h n i q u e s t h r o u g h p r e l i m i n a r y t r . i a l s on one c h a n n e l w h i l e r e s e r v i n g the r e m a i n i n g c h a n n e l f o r e x p e r i m e n t a t i o n . A more d e t a i l e d d e s c r i p t i o n of M a y f l y Creek and i t s watershed can be found i n Appendix A. 2.3 E x p e r i m e n t a l d e s i g n O v e r a l l , 4 d i f f e r e n t e x p e r i m e n t s were conducted w i t h each d e s i g n e d t o t e s t a s p e c i f i c h y p o t h e s i s ( T a b l e 2.1). Experiment 4 was conducted t w i c e , u s i n g Ephemeroptera nymphs and c h i r o n o m i d l a r v a e . The pr o c e d u r e i n a l l 5 e x p e r i m e n t s was e s s e n t i a l l y the Ta b l e 2.1 Hypotheses L a b o r a t o r y Experiment/Treatment F i e l d (1) Aluminum c h l o r i d e (2) H y d r o c h l o r i c a c i d (3) Aluminum c h l o r i d e f o l l o w i n g h y d r o c h l o r i c ac i d L a b o r a t o r y (4) C h o i i n e c h l o r i d e T e s t e d i n F i e l d and Ex p e r i m e n t s H y p o t h e s i s E l e v a t e d A l 3 + r e s u l t s i n avo i d a n c e b e h a v i o r M i l d l y e l e v a t e d H + does not r e s u l t i n a v o i d a n c e b e h a v i o r Response t o A l 3 + not s i m p l y due t o accumulated H + exposure Response t o A1C1 3 and HC1 not due t o e l e v a t e d C I " same; ambient water c h e m i s t r y was a l t e r e d and the b e h a v i o r a l response r e c o r d e d f o r exposed i n v e r t e b r a t e s . B i o l o g i c a l -response was m o n i t o r e d by s a m p l i n g i n v e r t e b r a t e d r i f t p a s s i n g F i g u r e 2.2 M a y f l y Creek: Study s i t e d e t a i l . S ampling s t a t i o n s a r e marked w i t h numbers, w i t h s i t e 1 ( c o n t r o l ) l o c a t e d a t the upstream end of the i s l a n d . Both d o s i n g s t a t i o n s (marked w i t h a dot) were l o c a t e d over a r i f f l e . The n o r t h e r n r i f f l e extended downstream t o s i t e 2, w h i l e the s o u t h e r n r i f f l e ended -2 m below the s o u t h d o s i n g s i t e . Between the bottom of t h a t r i f f l e and s i t e 3 t h e r e was a 2 m l o n g p o o l . S i t e 3 was l o c a t e d a t the head of a n other r i f f l e t h a t e x t e n d e d t o s i t e 4 and beyond. S t i p p l e d a r e a s r e p r e s e n t g r a v e l d e p o s i t s . D r i f t n e t s r e p r e s e n t e d by c o n i c a l symbols a t each sa m p l i n g s t a t i o n . MAYFLY CREEK t 1 Site ^Dos ing S t a t i o n sY^  I s l a n d Or, 18 from the t r e a t e d stream s e c t i o n . I t was assumed t h a t some a n i m a l s would show an a v o i d a n c e response by e n t e r i n g the water column and d r i f t i n g downstream. I n c r e a s e d d r i f t d e n s i t y (compared w i t h c o n t r o l samples) was then a t t r i b u t e d t o the e x p e r i m e n t a l c o n d i t i o n s . A n i m a l s r e s p o n d i n g w i t h i n the f i r s t s a m p l i n g p e r i o d were r e f e r r e d t o as h a v i n g responded i m m e d i a t e l y , compared w i t h groups where responses were d e l a y e d t o some l a t e r t i m e . In t h e s e e x p e r i m e n t s a n i m a l s were exposed t o 4 c h e m i c a l s : aluminum c h l o r i d e ( A 1 C 1 3 ) , h y d r o c h l o r i c a c i d (HC1), s u l f u r i c a c i d (H 2SO„), and c h o l i n e c h l o r i d e ( C 5 H 1 4 CI NO). Aluminum c h l o r i d e was s p e c i f i c a l l y chosen over o t h e r aluminum compounds because: (1) the amount of aluminum added t o the stream c o u l d be e a s i l y c a l c u l a t e d from C I " c o n c e n t r a t i o n s measured i n the water samples; (2) the amount of C I " added was c o n s i d e r e d t o be b i o l o g i c a l l y " u n i m p o r t a n t " (see S e c t . 2.3.3); and (3) HC1 c o u l d J be used as the c o r r e s p o n d i n g a c i d . S u l f u r i c a c i d and c h o l i n e c h l o r i d e were used o n l y i n the l a b o r a t o r y e x p e r i m e n t s (see T a b l e 2.3). Use of H 2 S 0 4 was p r e d i c a t e d on the assumption t h a t minor i n c r e a s e s i n d i s s o l v e d s u l f a t e ( S 0 4 ) would be b i o l o g i c a l l y u n i m p o r t a n t , because of the low t o x i c i t y of t h i s a n i o n t o f r e s h w a t e r l i f e (McNeely e t a l . 1979). C h o l i n e c h l o r i d e was chosen as a s o u r c e of C I " based upon the a s s u m p t i o n t h a t the c h o l i n e m o l e c u l e would have l i t t l e or no b i o l o g i c a l e f f e c t of i n t e r e s t i n t h e s e e x p e r i m e n t s . C h o l i n e compounds a r e w i d e l y used i n p h y s i o l o g i c a l e x p e r i m e n t a t i o n because c h o l i n e e x e r t s i n s i g n i f i c a n t o s m o t ic 19 p r e s s u r e and does not p e n e t r a t e most a n i m a l membranes ( E c k e r t and R a n d a l l 1978) . 2.3 .J_ Background s t u d i e s In p r e p a r a t i o n f o r the main e x p e r i m e n t a l s t u d i e s , i t was n e c e s s a r y t o d e t e r m i n e n a t u r a l d i e l d r i f t p a t t e r n s f o r t h i s s i t e . T h i s i n v o l v e d c o l l e c t i n g d r i f t i n g i n v e r t e b r a t e s h o u r l y f o r 24 h. D e t a i l s and r e s u l t s a r e i n S e c t . A.2 (Appendix A ) . A d d i t i o n a l l y , s e v e r a l t r i a l s were needed t o t e s t and r e f i n e methods and a p p a r a t u s r e q u i r e d f o r the main e x p e r i m e n t s . These were c a r r i e d out on the south s i d e of the i s l a n d ( F i g . 2.2) t o a v o i d d i s t u r b i n g the n o r t h stream c h a n n e l which was d e s i g n a t e d f o r use l a t e r i n the main e x p e r i m e n t s . 2.3.2 F i e l d e x p e r i m e n t s To t e s t the h y p o t h e s i s t h a t l o t i c i n v e r t e b r a t e s d e t e c t and a v o i d i n c r e a s e d d i s s o l v e d aluminum c o n c e n t r a t i o n s , a s o l u t i o n of aluminum c h l o r i d e was added d i r e c t l y t o M a y f l y Creek. B i o l o g i c a l response was examined by s a m p l i n g i n v e r t e b r a t e d r i f t below a r i f f l e a t two s i t e s ( F i g . 2.2) w i t h the upper s t a t i o n ( s i t e 1) s e r v i n g as a c o n t r o l , and samples from s i t e 2 p r o v i d i n g a measurement of b i o l o g i c a l response t o the t r e a t m e n t s . In l i g h t of known d r i f t p a t t e r n s a t t h i s s i t e (see S e c t . A.2) experiments were conducted d u r i n g d a y l i g h t hours t o m i n i m i z e c o m p l i c a t i n g f a c t o r s a s s o c i a t e d w i t h n i g h t t i m e " b e h a v i o r a l d r i f t " (Waters 1972). E x p e r i m e n t s were a l s o 20 conducted d u r i n g p e r i o d s of r e l a t i v e l y s t a b l e f l o w t o m i n i m i z e the i n f l u e n c e of " c a t a s t r o p h i c " d r i f t (Waters 1972). Once aluminum i s d i s s o l v e d i t c o n t r i b u t e s t o aqueous a c i d i t y , b u f f e r i n g a g a i n s t i n c r e a s e s i n pH (Johannessen 1980; Johnson et a l . 1981). C o n s e q u e n t l y , t o d e t e r m i n e whether observed d r i f t r esponses r e c o r d e d i n the aluminum c h l o r i d e experiment were due t o a c i d i t y or t o e l e v a t e d A l 3 + c o n c e n t r a t i o n , h y d r o c h l o r i c a c i d (HC1) was added t o M a y f l y Creek i n experiment 2 t o produce the same a c i d i t y as i n t h e aluminum experiment. The h y p o t h e s i s here was t h a t a s l i g h t l y e l e v a t e d hydrogen i o n c o n c e n t r a t i o n would not produce as s t r o n g a d r i f t response as e l e v a t e d A l 3 + c o n c e n t r a t i o n s . S i n c e aluminum s o l u b i l i t y i n f r e s h w a t e r v a r i e s w i t h pH and i s a t a minimum around pH 6.0, pH 5.9 was chosen as the t a r g e t H + c o n c e n t r a t i o n f o r b oth e x p e r i m e n t s 1 and 2. T h i s H + c o n c e n t r a t i o n m i n i m i z e d the d i s s o l v e d A l 3 + c o n c e n t r a t i o n , w h i l e p r e s e n t i n g the a n i m a l s w i t h s u b - l e t h a l H + i o n c o n c e n t r a t i o n s . To m i n i m i z e d i s r u p t i o n of t h e b e n t h i c community, experiments 1 (A1C1 3) and 2 (HC1) were c a r r i e d out i n r e v e r s e o r d e r . The n e c e s s a r y s o l u t i o n c o n c e n t r a t i o n s and dose r a t e s (see Appendix S e c t . B.1) were d e t e r m i n e d d u r i n g t h e e a r l i e r p i l o t s t u d i e s . Because b o t h e x p e r i m e n t s 1 and 2 o n l y t e s t e d s h o r t - t e r m (< 12 h) r esponses t o c h e m i c a l p e r t u r b a t i o n s , a t h i r d f i e l d experiment of i n t e r m e d i a t e l e n g t h (60 h > X >12 h) was c a r r i e d out t o t e s t the a d d i t i o n a l h y p o t h e s i s t h a t some- l o t i c i n v e r t e b r a t e s a r e t o l e r a n t of m i l d a c i d i f i c a t i o n , but i n t o l e r a n t 21 of e l e v a t e d aluminum c o n c e n t r a t i o n s , at the same pH. T h i s experiment was conducted on the s o u t h s i d e of the i s l a n d . HC1 was added t o the creek d e p r e s s i n g pH t o 5 . 9 . A f t e r two days of c o n t i n u o u s d o s i n g w i t h HC1, the s o l u t i o n was changed t o A1C1 3 and the d o s i n g r a t e i m m e d i a t e l y a d j u s t e d t o m a i n t a i n pH 5 . 9 f o r an a d d i t i o n a l 10 hours. D r i f t i n g i n v e r t e b r a t e s were sampled im m e d i a t e l y p r i o r t o s w i t c h i n g from HC1 to A1C1 3 and t h e r e a f t e r f o r an a d d i t i o n a l 8 hours. A g a i n , r e l a t i v e b i o l o g i c a l response t o the two s o l u t i o n s was examined by sampling i n v e r t e b r a t e d r i f t , o n l y t h i s time t h r e e s i t e s were used. Samples from the upper s t a t i o n ( s i t e 1) p r o v i d e d a c o n t r o l , w h i l e a measurement of b i o l o g i c a l response t o a l t e r e d stream c h e m i s t r y was p r o v i d e d by samples drawn from s i t e s 3 (at the downstream end of a p o o l ) and 4 (below a r i f f l e ) (see F i g . 2 . 2 ) . 2 . J 3 . 3 L a b o r a t o r y e x p e r i m e n t s In a l l 3 f i e l d e x p e r i m e n t s the s o l u t i o n added t o M a y f l y Creek c o n t a i n e d c h l o r i d e i o n s ( C l " ) . A l t h o u g h I c o u l d f i n d no e v i d e n c e i n the l i t e r a t u r e t h a t C l " can a f f e c t d r i f t i n g b e h a v i o r i n a q u a t i c i n v e r t e b r a t e s , I d e c i d e d to e x p l i c i t l y t e s t the h y p o t h e s i s t h a t m i l d l y e l e v a t e d C l " c o n c e n t r a t i o n s would not a f f e c t d r i f t i n g b e h a v i o r . T h i s h y p o t h e s i s was t e s t e d i n a l a b o r a t o r y experiment u s i n g a r t i f i c i a l stream c h a n n e l s , c h i r o n o m i d s from S p r i n g Creek and m a y f l i e s from a s m a l l t r i b u t a r y of J a c o b ' s Lake (Marion L a k e ) , b o t h s i t e s i n the U.B.C. Rese a r c h F o r e s t ( F i g . 2 . 1 ) . 22 E x p e r i m e n t a l c h a n n e l s were dosed w i t h c h o l i n e c h l o r i d e and a n i m a l e m i g r a t i o n was used as a measure of response t o a l t e r e d water c h e m i s t r y . 2.4 Methods and M a t e r i a l s 2.4.J[ F i e l d Experiments In these f i e l d e x p e r i m e n t s 12 parameters were r o u t i n e l y measured; they are l i s t e d , a l o n g w i t h t h e i r i m p o r t a n c e , i n T a b l e 2.2. Table 2.2. Parameters Measured i n F i e l d E x p e r i m e n t s Parameter B i o l o g i c a l d r i f t P h y s i c a l water v e l o c i t y water depth c o n d u c t i v i t y temperature s t a g e Chemical pH pH p r o f i l e aluminum c h l o r i d e a l k a l i n i t y d i s s o l v e d oxygen (D.O.) Importance a n i m a l response c a l c u l a t e volume f i l t e r e d by n e t s c a l c u l a t e volume f i l t e r e d by n e t s t o t a l i o n i c s t r e n g t h D.O. s a t u r a t i o n ; a d j u s t pH meter monitor d i s c h a r g e t r e n d s hydrogen i o n c o n c e n t r a t i o n monitor m i x i n g monitor c o n c e n t r a t i o n monitor c o n e ; c a l c . A l added b u f f e r i n g c a p a c i t y background c h e m i s t r y 23 2-4.J_.J_ Dr i f t sampling At each s t a t i o n r e p l i c a t e samples of d r i f t i n g i n v e r t e b r a t e s ( l e f t and r i g h t net p o s i t i o n s ) were c o l l e c t e d e v e r y 1.5 hours s t a r t i n g a t l e a s t 1.5 h b e f o r e c h e m i c a l d o s i n g began. D u r i n g each s a m p l i n g p e r i o d , n e t s were i n p l a c e f o r 45 min. The i n i t i a l s e t of samples s e r v e d not o n l y t o measure background d r i f t l e v e l s at each s i t e , but a l s o t o e s t a b l i s h a r e l a t i o n s h i p between d r i f t d e n s i t y a t the c o n t r o l and e x p e r i m e n t a l s i t e s . Stream d r i f t was sampled u s i n g s p e c i a l l y - d e s i g n e d 86 Lim mesh nets' ( d e s c r i b e d i n S e c t . B.1); f o l l o w i n g c o l l e c t i o n , samples were p r e s e r v e d w i t h 10 % f o r m a l i n and s e a l e d i n p l a s t i c bags f o r s t o r a g e . In the l a b o r a t o r y , a n i m a l s i n p r e s e r v e d samples were s e p a r a t e d from d e t r i t a l p a r t i c l e s by s i e v i n g t h r ough a 296 jum mesh f i l t e r . A n i m als from 7 d i f f e r e n t t a x a were enumerated: Ephemeroptera (Large ^ 2 mm > S m a l l ) , Chironomidae ( D i p t e r a ) (Large ^ 2 mm > S m a l l ) , T r i c h o p t e r a , H y d r a c a r i n a , H a r p a c t a c o i d a (Copepoda), Simulium ( D i p t e r a ) , and P l e c o p t e r a (Large > 2 mm > S m a l l ) . F u r t h e r d e t a i l s a r e p r o v i d e d i n S e c t . D.1. To p e r m i t comparison between net p o s i t i o n s ( l e f t and r i g h t ) , s t a t i o n s , and e x p e r i m e n t s , t o t a l number of a n i m a l s i n each taxon c a p t u r e d d u r i n g each 45 min s a m p l i n g p e r i o d was r e l a t e d t o the water volume f i l t e r e d by the n e t s as d e s c r i b e d by A l l a n and Russek (1985). C o n v e r s i o n f a c t o r s used a r e g i v e n i n T a b l e D.1. F i n a l r e s u l t s , t h e r e f o r e , a r e e x p r e s s e d as number of a n i m a l s from a g i v e n taxon d r i f t i n g per 10' L, an a r b i t r a r y but c o n s i s t e n t volume. 24 2.4.j_.2 P h y s i c a l measurements To p e r m i t c a l c u l a t i o n of water volume f i l t e r e d d u r i n g a sa m p l i n g p e r i o d , water v e l o c i t y and depth were r e c o r d e d f o r each net p o s i t i o n ( l e f t and r i g h t ) a t a l l s i t e s . Water v e l o c i t y was det e r m i n e d u s i n g an O t t c u r r e n t meter (Model C-2) w i t h which r e p l i c a t e , 30 second r e a d i n g s were taken at the s t a r t of a sa m p l i n g p e r i o d . F u r t h e r d e t a i l s a r e p r o v i d e d i n S e c t i o n s B.3 and D.2.1. Because t h e r e was no d i s c h a r g e gauging s t a t i o n a t M a y f l y Creek, an a r b i t r a r y , f i x e d - p o s i t i o n s t a d i u m was e s t a b l i s h e d . Stage measurements (water depth r e l a t i v e t o the stadium) were taken t w i c e d a i l y a t t h i s l o c a t i o n . E l e c t r i c a l c o n d u c t i v i t y was measured i n the l a b o r a t o r y u s i n g a Radiometer meter (CDM-3) on u n p r e s e r v e d samples taken, i n the f i e l d and s t o r e d a t 10°C u n t i l a n a l y s e d . These r e s u l t s were then c o n v e r t e d t o s p e c i f i c c o n d u c t i v i t y d a t a . 2.4.J_.3 Chemical s a m p l i n g With the e x c e p t i o n of hydrogen i o n s , grab samples f o r a l l o t h e r c h e m i c a l d e t e r m i n a t i o n s were s i m p l y taken a t some time d u r i n g the e x p e r i m e n t a l p e r i o d from both c o n t r o l and e x p e r i m e n t a l s i t e s . Hydrogen i o n c o n c e n t r a t i o n s were c o n s t a n t l y m o n i t o r e d and r e c o r d e d u s i n g a C o r n i n g c o m b i n a t i o n e l e c t r o d e , a t t a c h e d t o a H o r i z o n pH meter (5997-20), and a R u s t r a c k s t r i p -c h a r t r e c o r d e r . D u r i n g e x p e r i m e n t s 1 and 2 the e l e c t r o d e was p o s i t i o n e d a t s i t e 2, w h i l e i n experiment 3 i t was l o c a t e d a t s i t e 3. S u b g r a v e l pH was a l s o m o n i t o r e d by vacuuming water 25 samples t h r o u g h a s t a n d p i p e i n s e r t e d t o a depth of 0.5 m below the s u b s t r a t e / w a t e r i n t e r f a c e a t the edge of the stream. F u r t h e r d e t a i l s a r e p r o v i d e d i n S e c t . B.4.2. Water samples f o r m u l t i - e l e m e n t , d i s s o l v e d i o n c o n c e n t r a t i o n s , i n c l u d i n g A l , Ca, Mg, K, and Na, were f i l t e r e d (0.45 jum M i l l i p o r e ) , a c i d i f i e d (2 mL u l t r a p u r e HN0 3 ) , and s t o r e d i n new, acid-washed 150 mL p o l y e t h y l e n e b o t t l e s . P r i o r t o a n a l y s i s samples were c o n c e n t r a t e d by e v a p o r a t i o n t o < 50 mL. Samples were a n a l y s e d by Acme A n a l y t i c a l L a b o r a t o r y , Vancouver, u s i n g i n d u c t i v e l y c o u p l e d plasma s p e c t r o p h o t o m e t r i c (ICP) methods (see a l s o S e c t . B.4.5 and D.3.4). D u r i n g experiment 1, d i s s o l v e d , monomeric aluminum and added t o t a l aluminum c o n c e n t r a t i o n s were a l s o d e t e r m i n e d . Monomeric aluminum was e x t r a c t e d i n the f i e l d from f i l t e r e d (0.45 Mm M i l l i p o r e ) stream water u s i n g m e t h y l i s o b u t y l ketone (Barnes 1975), and e x t r a c t s were s t o r e d i n new, acid-washed p o l y e t h y l e n e c o n t a i n e r s (see Sec t B.4.1 f o r a more d e t a i l e d d e s c r i p t i o n ) . Monomeric aluminum c o n c e n t r a t i o n s were d e t e r m i n e d i n the l a b o r a t o r y u s i n g atomic a b s o r b t i o n (AA) methods. T o t a l , added aluminum c o n c e n t r a t i o n s were c a l c u l a t e d based upon C l " c o n c e n t r a t i o n s measured d u r i n g experiment 1. For each mole of C l " added t o the stream from t h e A1C1 3 s o l u t i o n , 1/3 mole A l 3 + was a l s o added. For more d e t a i l s on aluminum d e t e r m i n a t i o n s see S e c t . D.3.1. U n f i l t e r e d water samples were c o l l e c t e d f o r c h l o r i d e a n a l y s i s i n c l e a n p o l y e t h y l e n e c o n t a i n e r s and s t o r e d a t 10°C u n t i l a n a l y s e d . C h l o r i d e c o n t e n t was d e t e r m i n e d u s i n g 26 c o l o r i m e t r i c m e r c u r i c n i t r a t e t i t r a t i o n s (APHA 1984). A l k a l i n i t y was measured by t i t r a t i n g 500 mL water samples w i t h 0.005 N HC1 ( F i s h e r c e r t i f i e d ) and p l o t t i n g the r e s u l t s a c c o r d i n g t o the methods of Gran (see Stumm and Morgan 1970). A d d i t i o n a l d e t a i l s can be found i n S e c t . B.4.3 and D.3.3. I ' l - l - l Data a n a l y s i s A nimal c o u n t s were a d j u s t e d t o s t a n d a r d volume ( 1 0 4 L) and then a n a l y z e d ( w i t h o u t t r a n s f o r m a t i o n ) u s i n g the MINITAB s t a t i s t i c a l package (Ryan et a l . 1981). Data from th e s e f i e l d e x p e r i m e n t s were summarized i n t o t a b l e s , and where a p p r o p r i a t e p l o t t e d and v i s u a l l y e v a l u a t e d . 2.i.2 L a b o r a t o r y E x p e r i m e n t s B i o l o g i c a l responses t o e l e v a t e d c h l o r i d e i o n c o n c e n t r a t i o n s i n l a b o r a t o r y e x p e r i m e n t s 4 and 5 were measured at two H + i o n l e v e l s and two C I " l e v e l s a t each pH (Table 2.3). Choosing pH 5.9 a l l o w e d comparison w i t h r e s u l t s of p r e v i o u s f i e l d e x p e r i m e n t s . Two a c i d s were used t o lower pH, HCl and H 2SO f l, and c h o l i n e c h l o r i d e was used t o e l e v a t e C I " c o n c e n t r a t i o n s . To m i n i m i z e e x p e r i m e n t a l b i a s , t r e a t m e n t s and an i m a l s were a r b i t r a r i l y a s s i g n e d t o e x p e r i m e n t a l t r o u g h s , w i t h 3 r e p l i c a t e s per t r e a t m e n t . 27 T a b l e 2.3 C h l o r i d e Experiment: Treatments (a H + C o n c e n t r a t i o n [ C l - ] Ephemeroptera (mg/L) p_H 6.2 pH 5.9 Chironomids p_H 6.9 pH 6.2 1 .5 C o n t r o l H 2SO f l C o n t r o l H 2SO« 5.5 C h o l i n e C h l o r i d e HC1 C h o i i n e C h l o r i d e HC1 (a E x p e r i m e n t a l C o n d i t i o n s : Water v e l o c i t y (mL/min.) 970 Water temperature (°C) 15.5 Animals/Trough 6 970 15.5 9 2.4.2.j_ B i o l o g i c a l Ephemeroptera nymphs f o r use i n these l a b o r a t o r y e x p e r i m e n t s were c o l l e c t e d d u r i n g d a y l i g h t hours from i n v e r t e b r a t e d r i f t i n the s o u t h e a s t t r i b u t a r y t o Jacobs Lake on August 31, 1985 u s i n g 86 nm mesh n e t s . To s t i m u l a t e d r i f t and ensure t h a t a n i m a l s used i n the l a b o r a t o r y t e s t s were, i n d e e d , " s e n s i t i v e " t o changes i n water q u a l i t y , an aluminum s o l u t i o n was d r i p p e d i n t o the stream a t a r a t e t h a t produced pH 5.7 (background pH 6.9). Immediately a f t e r c o l l e c t i n g the nymphs I t r a n s f e r r e d them t o uncontaminated w a t e r , packed on i c e , and t r a n s p o r t e d them t o the l a b o r a t o r y . C h i ronomids were c o l l e c t e d by i n c u b a t i n g l e a f - p a c k s i n S p r i n g Creek f o r 2 weeks d u r i n g August, 1985. A f t e r r e c o v e r y , a n i m a l s f o r use i n the e x p e r i m e n t s were m a n u a l l y s o r t e d from t h e l e a f - p a c k s . F o l l o w i n g a 24 h o b s e r v a t i o n p e r i o d ( d u r i n g which m o r t a l i t y 28 was < 5 % ) , a n i m a l s were then exposed t o t e s t s o l u t i o n s f o r 3 h o u r s . E m i g r a t i n g a n i m a l s were c o l l e c t e d from b o t h c o n t r o l and e x p e r i m e n t a l c h a n n e l s and response was d e t e r m i n e d by comparing numbers e m i g r a t i n g i n response t o each t r e a t m e n t . 2.4.2.2 P h y s i c a l - c h e m i c a l Water samples f o r C I " a n a l y s e s were taken from each c h a n n e l a t the end of 2.5 h. C h l o r i d e c o n c e n t r a t i o n s were d e t e r m i n e d u s i n g m e r c u r i c n i t r a t e t i t r a t i o n s . Hydrogen i o n c o n c e n t r a t i o n s were c o n s t a n t l y m o n i t o r e d and r e c o r d e d . 2.4.2.3 Data a n a l y s i s Data on the p r o p o r t i o n of each s p e c i e s d r i f t i n g out of each c h a n n e l were t r a n s f o r m e d ( a r c s i n square r o o t ) and then a n a l y s e d u s i n g a n a l y s i s of v a r i a n c e from the GLIM ( R o y a l S t a t i s t i c a l S o c i e t y ) s t a t i s t i c a l package. P r o b a b i l i t y v a l u e s f o r each F s t a t i s t i c were c a l c u l a t e d by the UNIX s t a t i s t i c a l r o u t i n e "pof". S t a t i s t i c a l s i g n i f i c a n c e was judged a t p < 0.05. 29 CHAPTER 3. RESULTS OF FIELD AND LABORATORY EXPERIMENTS 3_._1_ R e s u l t s of f i e l d e x p e r i m e n t s _3._l_.j_ Experiment E f f e c t s of A l 3 * On 26 August, 1982 an aluminum c h l o r i d e (A1C1 3) s o l u t i o n (see S e c t . B.1) was added t o the n o r t h branch of M a y f l y Creek c o n t i n u o u s l y from 0915 h u n t i l 2030 h. From a d o s i n g s t a t i o n 15 m upstream ( F i g . 2.2), aluminum c h l o r i d e was a d m i n i s t e r e d a t a r a t e t h a t r e s u l t e d i n stream water pH 5.9 a t s i t e 2. On t h i s ' d a t e median pH f o r the c o n t r o l s e c t i o n was 6.9. Over a 30-minute p e r i o d , a c i d i t y was r a i s e d i n the e x p e r i m e n t a l s e c t i o n and then h e l d r e l a t i v e l y c o n s t a n t (see S e c t . 3.1.1.2) f o r the next 11 h o u r s . When s o l u t i o n a d d i t i o n was t e r m i n a t e d stream water pH r e t u r n e d t o p r e - a d d i t i o n l e v e l s i n 15 min. D r i f t d e n s i t y was measured a t two l o c a t i o n s (see F i g . 2.2), w i t h d r i f t samples from upstream ( s i t e 1) s e r v i n g as a r e f e r e n c e ( c o n t r o l ) a g a i n s t which samples from downstream ( s i t e 2) c o u l d be compared. B i o l o g i c a l response P r e c e d i n g aluminum a d d i t i o n , t o t a l d r i f t d e n s i t y a t b o t h the c o n t r o l and e x p e r i m e n t a l s e c t i o n s was s i m i l a r but s l i g h t l y l ower a t the c o n t r o l s i t e ( F i g . 3.1). A f t e r aluminum d o s i n g began, d r i f t d e n s i t y i n the c o n t r o l stream s e c t i o n remained r e l a t i v e l y c o n s t a n t (mean = 62 an i m a l s / 1 0 " L ) , w h i l e a t the 30 EXPERIMENT 1 TOTAL DRIFT „ 600 P H 1 1 1 1 h 0600 0900 1200 1500 1800 2100 HOUR F i g u r e 3.1. T o t a l D r i f t Response t o A1C1 3 a l o n e , pH 5.9. • S i t e 1. n S i t e 2. A1C1 3 added from 0915 h u n t i l 2030 h, 26 August 1982. 31 e x p e r i m e n t a l stream segment, d e n s i t y more than t r i p l e d from a p r e - t r e a t m e n t c o n c e n t r a t i o n of =160 a n i m a l s / 1 0 4 L t o > 550 a n i m a l s / 1 0 4 L. However, as seen i n F i g . 3.1, t h e r e were two phases t o the o v e r a l l r esponse. Immediately a f t e r a dding aluminum, and w i t h i n the f i r s t s a m p l i n g p e r i o d (45 m i n ) , d r i f t d e n s i t y i n the e x p e r i m e n t a l stream s e c t i o n a b r u p t l y doubled and remained a t t h i s l e v e l f o r 6 h. At the end of t h i s time p e r i o d , d r i f t d e n s i t y suddenly doubled a g a i n and remained a t t h i s h i g h e r l e v e l u n t i l the experiment was t e r m i n a t e d 4.5 h l a t e r . S i n c e n e i t h e r dose r a t e nor stream pH changed a t the end of the f i r s t 6 h p e r i o d , observed v a r i a t i o n s i n d r i f t d e n s i t y a r e a t t r i b u t e d to d i f f e r e n c e s i n the r a t e of b i o l o g i c a l response by d i v e r s e taxonomic groups. N u m e r i c a l l y , two t a x a dominated the i n c r e a s e i n d r i f t d e n s i t y a t s i t e 2 — s m a l l i n d i v i d u a l s of the groups Ephemeroptera and Chironomidae ( D i p t e r a ) (Table 3.1). Data from a l l s a m p l i n g p e r i o d s a t both s i t e s were p o o l e d t o produce T a b l e 3.1. W h i l e d r i f t d e n s i t y f o r each taxonomic group remained r e l a t i v e l y c o n s t a n t at the c o n t r o l s i t e ( 1 ) , t h i s was not the case at the e x p e r i m e n t a l s i t e . C o n s e q u e n t l y , v a l u e s f o r mean d r i f t d e n s i t y at s i t e 2 ( T able 3.1) a r e o n l y c o a r s e i n d i c a t o r s of which a n i m a l groups were s t i m u l a t e d by the t r e a t m e n t , and c o n c e a l the dynamic n a t u r e of t h e o b s e r v e d r e s p o n s e s . By examining t i m e - s e r i e s p l o t s of d r i f t d e n s i t y , the response (or non-response) by each group can be e v a l u a t e d . In the f o l l o w i n g p a r a g r a p h s , I d e s c r i b e the b e h a v i o r observed* f o r each group d u r i n g the e x p e r i m e n t a l p e r i o d . 32 T a b l e 3.1.- D r i f t Response t o A l 3 + Taxon Mean Dr i f t d e n s i t y ( a n i m a l s / 1 0 " L) S i t e 1 S i t e 2 SD n Mean SD n Ephem-Sm 3.3 Ephem-Lg 0.3 Chiron-Sm 45.0 C h i r o n - L g 2.0 T r i c h o p 1.6 Hydrac 4.3 Harpact 4.2 Simulium 0.5 Plecopt-Sm 0.7 P l e c o p t - L g 0 1 .9 0.6 14.1 1 .4 1 .2 2.2 3.4 1 .6 1 . 1 18 18 18 18 18 18 18 18 18 18 103.9 5.2 252.8 50.2 5.0 18 18 18 18 18 18 18 18 18 18 131.1 4.7 5.9 9.5 5.6 0.6 1 . 4 0 4.2 6.1 5.7 5.0 0.9 1 .6 P r i o r t o s t a r t i n g t h e e x p e r i m e n t , d r i f t d e n s i t i e s f o r l a r g e and s m a l l Ephemeroptera a t b o t h s i t e s 1 and 2 were v e r y s i m i l a r ( F i g . 3.2a,b). A f t e r aluminum a d d i t i o n s began, i n d i v i d u a l s of both s i z e c l a s s e s responded i m m e d i a t e l y ( w i t h i n 45 min) t o the a l t e r e d water c h e m i s t r y . D r i f t d e n s i t y f o r s m a l l i n d i v i d u a l s r o s e above 75 a n i m a l s / 1 0 " L and remained e l e v a t e d u n t i l aluminum a d d i t i o n was t e r m i n a t e d 10 hours l a t e r ( F i g . 3.2a). By compari s o n , mean d r i f t d e n s i t y of s m a l l m a y f l i e s a t the c o n t r o l s i t e was low (3.3 a n i m a l s / 1 0 " L) and r e l a t i v e l y c o n s t a n t . The response by l a r g e Ephemeroptera t o aluminum t r e a t m e n t was l e s s c l e a r , s i n c e d r i f t d e n s i t y a t s i t e 2 remained low (max. 12 a n i m a l s / 1 0 " L) and e r r a t i c ( F i g . 3.2b). D e s p i t e the l a r g e v a r i a b i l i t y i n d r i f t d e n s i t y f o r t h i s group a t s i t e 2, i t s h o u l d be noted t h a t the r e c o r d e d peaks were 40 t i m e s h i g h e r than l e v e l s a t s i t e 1 where l a r g e Ephemeroptera seldom d r i f t e d (mean = 0.3 a n i m a l s / 1 0 " L ) . T h i s e r r a t i c response may have been caused by low p o p u l a t i o n d e n s i t y , s e v e r a l s p e c i e s - r e s p o n d i n g a t d i f f e r e n t t i m e s , or some o t h e r f a c t o r . At l e a s t t e n s p e c i e s of 33 150 100 j 50 cn r—i m 6 c (0 EXPERIMENT 1 SMALL EPHEMEROPTERA X E-K-i to z w a a n LARGE EPHEMEROPTERA 15 10 B 0600 0900 1200 1500 HOUR 1800 2100 F i g u r e 3.2a,b. Ephemeroptera D r i f t Response t o A1C1 3 a l o n e , pH 5.9. • S i t e 1. n S i t e 2. A1C1 3 added from 0915 h u n t i l 2030 h, 26 August 1982. 34 Ephemeroptera i n h a b i t t h i s s i t e (Sec. A.1.2.1). At both the c o n t r o l and e x p e r i m e n t a l s i t e s , p r e - a d d i t i o n d r i f t d e n s i t y f o r s m a l l and l a r g e c h i r o n o m i d s was s i m i l a r ( F i g . 3.3a,b). F o l l o w i n g aluminum a d d i t i o n , d r i f t d e n s i t y f o r s m a l l i n d i v i d u a l s a t s i t e 2 g r a d u a l l y i n c r e a s e d ; 6 h a f t e r aluminum c o n c e n t r a t i o n s were e l e v a t e d , >350 s m a l l c h i r o n o m i d s / 1 0 " L were d r i f t i n g out of the e x p e r i m e n t a l stream s e c t i o n ( F i g . 3.3a). The i n c r e a s e i n d r i f t d e n s i t y f o r t h i s group r e p r e s e n t e d an ob v i o u s and s u b s t a n t i a l i n c r e a s e over mean d r i f t d e n s i t y a t the c o n t r o l s i t e (45 a n i m a l s / l O " L ) . D u r i n g t h i s p e r i o d , d r i f t d e n s i t y f o r l a r g e c h i r o n o m i d s appeared t o s t e a d i l y i n c r e a s e a t s i t e 2, but the numbers c a p t u r e d were always low (max. =8 i n d i v i d u a l s / 1 0 " L) ( F i g . 3.3b). At s i t e 1, background d r i f t d e n s i t y was r e l a t i v e l y c o n s t a n t a t 2.0 large- c h i r o n o m i d s / 1 0 " L. D e s p i t e an u n u s u a l l y h i g h p r e - a d d i t i o n d r i f t d e n s i t y f o r T r i c h o p t e r a at s i t e 2, t h e r e was a w e l l - d e f i n e d but d e l a y e d (>6 h) response t o i n c r e a s e d d i s s o l v e d aluminum c o n c e n t r a t i o n s ( F i g . 3.4a). Peak d r i f t d e n s i t y i n the e x p e r i m e n t a l stream s e c t i o n was =15 T r i c h o p t e r a / 1 0 " L, an o r d e r - o f - m a g n i t u d e h i g h e r than a t the c o n t r o l s i t e (mean= 1.6 a n i m a l s / 1 0 " L ) . F o l l o w i n g the peak i n d r i f t d e n s i t y , numbers of T r i c h o p t e r a l e a v i n g the e x p e r i m e n t a l stream s e c t i o n r a p i d l y d e c l i n e d and when the experiment ended d r i f t d e n s i t y a t the two s i t e s was n e a r l y e q u a l ( F i g . 3.4a). A l t h o u g h the s i z e of the s e a n i m a l s was not r e c o r d e d , n e a r l y a l l c a p t u r e d a n i m a l s were < 5 mm i n l e n g t h . Response by H y d r a c a r i n a t o e l e v a t e d d i s s o l v e d aluminum c o n c e n t r a t i o n s was a l s o w e l l - d e f i n e d and d e l a y e d by 6 h ( F i g . 35 0600 0900 1200 1500 1800 2100 HOUR F i g u r e 3.3a,b. Chironomidae D r i f t Response t o A1C1 3 a l o n e , pH 5.9. • S i t e 1. n S i t e 2. A1C1 3 added from 0915 h u n t i l 2030 h, 26 August 1982. 36 EXPERIMENT 1 TRICHOPTERA H 1 1 1 1 f 0600 0900 1200 1500 1800 2100 HOUR F i g u r e 3.4a,b. T r i c h o p t e r a and H y d r a c a r i n a D r i f t Response t o A1C1 3 a l o n e , pH 5.9. • S i t e 1. n S i t e 2. A1C1 3 added from 0915 h u n t i l 2030 h, 26 August 1982. 37 3.4b). A f t e r r e a c h i n g a maximum d r i f t d e n s i t y of r o u g h l y 17 i n d i v i d u a l s / 1 0 " L, d r i f t d e n s i t y began t o d e c l i n e . Throughout the e x p e r i m e n t , numbers of a n i m a l s d r i f t i n g p a s t the c o n t r o l s i t e remained low and r e l a t i v e l y c o n s t a n t (mean =4.3 animal s / 1 0 " L ) . Dur i n g aluminum d o s i n g t h e r e was no d e t e c t a b l e response by h a r p a c t a c o i d copepods, Simulium, or s m a l l P l e c o p t e r a . As w e l l , d u r i n g t h i s p e r i o d no l a r g e P l e c o p t e r a d r i f t e d from e i t h e r the c o n t r o l or e x p e r i m e n t a l reaches of M a y f l y Creek. _3.J_._1_._2 P h y s i c a l - c h e m i c a l c o n d i t i o n s 'On the date of t h i s e x p e r i m e n t , M a y f l y Creek d i s c h a r g e was r e l a t i v e l y c o n s t a n t and a t , or near, b a s e - f l o w c o n d i t i o n s ( F i g . 3.5b). P r e v i o u s l y , d i s c h a r g e had been d e c l i n i n g a t t h i s s i t e f o l l o w i n g a r a i n f a l l event t h a t ended on 13 August (see F i g . 3.5a) . Adding aluminum c h l o r i d e s a l t s i n c r e a s e d s p e c i f i c c o n d u c t i v i t y s l i g h t l y from 23 yS/cm t o 28 juS/cm. D u r i n g the experi m e n t , a i r temperature v a r i e d between 12°C and 18°C w h i l e water t e m p e r a t u r e s s l o w l y rose from 13°C t o 14°C. A c i d i t y a t s i t e 2 d u r i n g the experiment was e l e v a t e d one or d e r - o f - m a g n i t u d e above t h a t a t the c o n t r o l s i t e ( T a ble 3.2). Al t h o u g h a c o n s t a n t head r e s e r v o i r was not used f o r s o l u t i o n d e l i v e r y , c o n s t a n t m o n i t o r i n g of stream water pH throughout the e x p e r i m e n t a l p e r i o d showed t h a t v a r i a t i o n i n hydrogen i o n c o n c e n t r a t i o n was m i n i m a l ; mean H + c o n c e n t r a t i o n was 1.19 X 1 0 - 6 mol/L (SD=0.51, n = 4 l ) . A c a r e f u l survey of stream 38 42 AUGUST 1982 ~ 28 14 28.5 t B ~ 26.0 + g 23.5 + 21.0 + t • • • • • • 16 DAY 24 32 F i g u r e 3.5a,b. R a i n f a l l and M a y f l y Creek D i s c h a r g e , August 1982. 39 Ta b l e 3.2. Water C h e m i s t r y : Experiment 1 D i s s o l v e d C o n c e n t r a t i o n S i t e 1 S i t e 2 Mean SD (a Mean SD >arameter n = 2 n = 2 pH 6.9 - 5.9 -A l (jug/L) 62.5 17.7 95.9 42.4 Ca (mg/L) 2.56 0.11 2.78 0.01 C l (mg/L) 0.62 0.15 5.21 -Mg (mg/L) 0.50 0.13 0.48 0.05 K (mg/L) 0.09 0.03 0.11 0.01 Na (mg/L) 1 .24 0.12 1 .32 0.06 a l k a l i n i t y 6.20 - 2.00 -(as CaC0 3) (a P o o l e d 25,26 Aug. v a l u e s . water pH below the a d d i t i o n s i t e i n d i c a t e d t h a t the aluminum s o l u t i o n was r a p i d l y (< 2 m) mixed by t u r b u l e n c e i n the r i f f l e ; no a c i d i c plumes were d e t e c t e d f u r t h e r downstream. Background C l " c o n c e n t r a t i o n a t M a y f l y Creek was.0.62 mg/L. D u r i n g A1C1 3 a d d i t i o n s , C l " l e v e l s i n c r e a s e d n e a r l y an o r d e r - o f -magnitude w h i l e a l k a l i n i t y dropped by n e a r l y t w o - t h i r d s (Table 3.2). D i s s o l v e d i o n c o n c e n t r a t i o n s f o r A l , Ca, K, and Na were h i g h e r i n the e x p e r i m e n t a l stream s e c t i o n than a t s i t e 1. Monomeric aluminum c o n c e n t r a t i o n s a t the c o n t r o l s i t e were 50-75 Mg/L, compared w i t h > 225 Mg/L a t s i t e 2 d u r i n g the ex p e r i m e n t . However, t h i s l a t t e r v a l u e may have been i n f l a t e d by sample e v a p o r a t i o n d u r i n g s t o r a g e . T o t a l added aluminum c o n c e n t r a t i o n , c a l c u l a t e d from stream water C l " c o n t e n t , was 1.14 mg/L. 40 3 .J_. 2 Experiment 2: E f f e c t s of H* On 25 August, 1982 the n o r t h b ranch of M a y f l y Creek was c o n t i n u o u s l y dosed w i t h a h y d r o c h l o r i c a c i d s o l u t i o n (see S e c t . B.1) from 0845 h u n t i l 2015 h. The s o l u t i o n was a d m i n i s t e r e d a t a r a t e t h a t r e s u l t e d i n stream water pH 5.9 a t the downstream s t a t i o n ( s i t e 2) and was d e l i v e r e d from a l o c a t i o n 15 m upstream (see F i g . 2.2). Over a 30-minute p e r i o d a c i d i t y i n the e x p e r i m e n t a l s e c t i o n was i n c r e a s e d t o pH 5.9, from a p r e -a c i d i f i c a t i o n l e v e l of pH 7.0. _3.J_._2._I_ B i o l o g i c a l response P r i o r t o a c i d a d d i t i o n , t o t a l d r i f t d e n s i t y f o r b o t h c o n t r o l and e x p e r i m e n t a l a r e a s was s i m i l a r ( F i g . 3.6). F o l l o w i n g e l e v a t i o n of H + i o n c o n c e n t r a t i o n , d r i f t d e n s i t y i n the e x p e r i m e n t a l s e c t i o n ( s i t e 2) i n c r e a s e d from a p r e -a c i d i f i c a t i o n l e v e l of ^90 a n i m a l s / 1 0 " L t o a maximum of about 310 a n i m a l s / 1 0 " L. D e s p i t e the f a c t t h a t stream pH remained d e p r e s s e d , d r i f t d e n s i t y a t s i t e 2 s t a r t e d t o d e c l i n e 7 hours a f t e r d o s i n g began. Throughout the e x p e r i m e n t a l p e r i o d , d r i f t at the c o n t r o l s i t e remained r e l a t i v e l y c o n s t a n t a t a p p r o x i m a t e l y 75 a n i m a l s / 1 0 " L ( F i g . 3.6). Maximum d r i f t d e n s i t y o b s e r v e d d u r i n g t h i s e xperiment was j u s t s l i g h t l y over 1/2 t h a t r e c o r d e d i n experiment 1. S m a l l Ephemeroptera, both s i z e s of c h i r o n o m i d s , and T r i c h o p t e r a a c c o u n t e d f o r most of the i n c r e a s e d d r i f t d e n s i t y ( T a b l e 3.3). D r i f t d e n s i t y f o r s m a l l P l e c o p t e r a a t s i t e 2 was 41 EXPERIMENT 2 TOTAL DRIFT •i 1 1 1 1 1_ 0600 0900 1200 1500 1800 2100 HOUR F i g u r e 3.6. T o t a l D r i f t Response t o HC1 a l o n e , pH 5.9. • S i t e 1. n S i t e 2. HC1 s o l u t i o n added from 0845 h u n t i l 2015 h, 25 August 1982. 42 T a b l e 3.3. D r i f t Response t o H + D r i f t d e n s i t y ( a n i m a l s / 1 0" L) S i t e 1 S i t e 2 Taxon Mean SD n Mean SD Ephem-Sm 3.7 2 .7 20 14.6 7.6 20 Ephem-Lg . 0.3 0 .6 20 0.8 1 .2 20 Chiron-Sm 54.2 1 3 .7 20 148.3 53.0 20 Chi ron-Lg 2.0 1 .4 20 6.0 5. 1 20 Tr i c h o p 2.2 1 .6 20 10.4 7.4 20 Hydrac 6.3 3 .8 20 10.2 6.8 20 Harpact 5.0 2 .3 20 8.3 6.2 20 Simulium 0.1 0 .2 20 0.3 0.7 20 Plecopt-Sm 0.8 0 .6 20 4.3 3.0 20 P l e c o p t - L g 0 - 20 0.3 0.7 20 h i g h e r than a t the c o n t r o l s i t e f o r a l l s a m p l i n g p e r i o d s , but d i s p l a y e d no t r e n d s . In c o n t r a s t t o t h e i r immediate response under A1C1 3 a d d i t i o n , s m a l l Ephemeroptera responded t o d e c r e a s e d pH s l o w l y , e x h i b i t i n g a 6-hour i n c r e a s e , f o l l o w e d by a slow, 4-hour decrease i n d r i f t d e n s i t y ( F i g . 3.7a). Ephemeroptera d r i f t d e n s i t y a t each s i t e (1 and 2) was s i m i l a r p r i o r t o a c i d i f i c a t i o n ; d e n s i t y a t the c o n t r o l s i t e remained r e l a t i v e l y s t a b l e a t 3.7 a n i m a l s / 1 0 " L. L a r g e m a y f l i e s may a l s o have responded t o i n c r e a s e d a c i d i t y ; i f so, the response appears t o have been d e l a y e d 4-5 hours ( F i g . 3.7b). U n f o r t u n a t e l y , i n t e r p r e t a t i o n of the d a t a f o r l a r g e Ephemeroptera i s s e v e r e l y c o n s t r a i n e d by the s m a l l d r i f t d e n s i t i e s i n v o l v e d (max. =2.1 an i m a l s / 1 0 " L) and the anomalously e l e v a t e d p r e - a c i d i f i c a t i o n d e n s i t y . In c o n t r a s t t o the slow i n c r e a s e i n t h e i r d r i f t a f t e r A1C1 3 was added i n experiment 1, d r i f t d e n s i t y f o r s m a l l c h i r o n o m i d s i n c r e a s e d i m m e d i a t e l y and remained e l e v a t e d (>150 a n i m a l s / 1 0 " L) 43 30 EXPERIMENT 2 SMALL EPHEMEROPTERA o \ Ul r—i ca e c (0 20 10 E-| 2.25 p E-EL4 LARGE EPHEMEROPTERA Q 1.5 0.75 0600 0900 1200 1500 HOUR 1800 2100 F i g u r e 3.7a,b. Ephemeroptera D r i f t Response t o HC1 a l o n e , pH 5.9. • S i t e 1. n S i t e 2. HC1 s o l u t i o n added from 0845 h u n t i l 2015 h, 25 August 1982. 44 f o r more than 7 h b e f o r e s t a r t i n g t o d e c l i n e ( F i g . 3.8a). T h i s was i n s h a r p c o n t r a s t t o the c o n t r o l s e c t i o n where mean d e n s i t y remained around 54 s m a l l c h i r o n o m i d s / 1 0 " L. A l s o i n c o n t r a s t t o t h e i r response w i t h A1C1 3 a d d i t i o n , l a r g e c h i r o n o m i d s responded q u i t e r a p i d l y but d r i f t d e n s i t i e s began t o d e c l i n e a f t e r < 3 h exposure t o HC1 ( F i g . 3.8b). I n the e x p e r i m e n t a l s e c t i o n , d r i f t d e n s i t y f o r t h i s group had d e c l i n e d a t the end of 7 h t o p r e - a c i d i f i c a t i o n l e v e l s . Mean d r i f t d e n s i t i e s under H + were about the same as under A l 3 + a d d i t i o n s . Throughout the day, d e n s i t y of l a r g e c h i r o n o m i d s d r i f t i n g past the c o n t r o l s i t e remained around 2 a n i m a l s / 1 0 " L. U n l i k e under A1C1 3 t r e a t m e n t , where T r i c h o p t e r a responded s l o w l y i n response t o the HC1 t r e a t m e n t , T r i c h o p t e r a responded almost i m m e d i a t e l y and i n g r e a t e r numbers ( F i g . 3.9a). D r i f t d e n s i t i e s remained e l e v a t e d f o r r o u g h l y 6 h, a t which time the number of a n i m a l s e x i t i n g the e x p e r i m e n t a l stream s e c t i o n began t o d e c l i n e r a p i d l y . When the experiment ended, c a d d i s f l y d r i f t d e n s i t y a t s i t e 2 had r e t u r n e d t o p r e - a c i d i f i c a t i o n l e v e l s and was n e a r l y e q u a l t o t h a t a t s i t e 1. Peak d r i f t d e n s i t y a t s i t e 2 was >15 a n i m a l s / 1 0 " L; f o r c o m p a r i s o n , mean d r i f t , d e n s i t y i n the c o n t r o l s e c t i o n was 2.2 a n i m a l s / 1 0 " L. A f t e r HC1 d o s i n g began, a few Simulium (<1.5 a n i m a l / 1 0 " L) appeared i n n e t s at s i t e 2 ( F i g . 3.9b). Because the b e n t h i c community a t M a y f l y Creek c o n t a i n e d l i m i t e d numbers of Simulium (max. n o c t u r n a l d r i f t d e n s i t y =*7 a n i m a l s / 1 0 " L; see S e c t . A.2.2), i n t e r p r e t a t i o n of these d a t a are e q u i v o c a l . At no time d u r i n g the e x p e r i m e n t , though, were s i m u l i i d s ever r e c o r d e d 45 250 in. (0 a • i H c fO 175 100 50 0 co z u p 1—1 p 1 5 10 EXPERIMENT 2 SMALL CHIRONOMIDAE f LARGE CHIRONOMIDAE B -+- -+-0600 0900 1200 1500 HOUR 1800 2100 F i g u r e 3.8a,b. Chironomidae D r i f t Response t o HCl a l o n e , pH 5.9. • S i t e 1. n S i t e 2. HCl s o l u t i o n added from 0845 h u n t i l 2015 h, 25 August 1982. 46 22.5 15.0 o 7.5 \ ui <—i m E • r - l s 0 EXPERIMENT 2 TRICHOPTERA E-•-t CO 2 u Q EH r—( a p 1 .5 1.0 0.5 SIMULIUM 0600 0900 1200 1500 HOUR 1800 2100 F i g u r e 3.9a,b. T r i c h o p t e r a and Simulium D r i f t Response t o HC1 a l o n e , pH 5.9. • S i t e 1. n S i t e 2. HC1 s o l u t i o n added from 0845 h u n t i l 2015 h, 25 August 1982. 47 d r i f t i n g a t s i t e 1. As under A1C1 3 a d d i t i o n , h a r p a c t a c o i d copepods as w e l l as s m a l l and l a r g e P l e c o p t e r a never responded t o a c i d i f i c a t i o n . In c o n t r a s t t o A1C1 3 a d d i t i o n , H y d r a c a r i n a showed no e v i d e n c e of i n c r e a s e d d r i f t d e n s i t y under HCl a d d i t i o n . 3.]_.2.2 P h y s i c a l - c h e m i c a l c o n d i t i o n s D u r i n g t h i s experiment, d i s c h a r g e was r e l a t i v e l y c o n s t a n t a t , or near, b a s e - f l o w c o n d i t i o n s (see F i g . 3.5). Median pH f o r the c o n t r o l s e c t i o n was s l i g h t l y h i g h e r (pH 7.0) than i n experiment 1, w h i l e i n the e x p e r i m e n t a l s e c t i o n i t was t h e same as i n experiment 1, pH 5.9 (mean H += 1.12 X 10" 6, SD=0.54, n=44; Tab l e 3.4). As i n experiment 1, an a c i d i t y s u r v e y showed t h a t the a c i d s o l u t i o n was w e l l mixed w i t h the stream water w i t h i n about 2 m below the d o s i n g s t a t i o n . D u r i n g HCl a d d i t i o n s , C l " c o n c e n t r a t i o n (Table 3.4) was e l e v a t e d t o o n l y 1/2 t h e l e v e l r e c o r d e d d u r i n g the f i r s t e x p e r i m e n t . D u r i n g e x p e r i m e n t 2, a l k a l i n i t y a t the e x p e r i m e n t a l s i t e dropped t o about the- same l e v e l as i n the f i r s t e x periment. D i s s o l v e d i o n c o n c e n t r a t i o n s i n the a c i d i f i e d stream s e c t i o n were s l i g h t l y h i g h e r f o r aluminum, c a l c i u m , magnesium, and sodium (Table 3.4). _3.J_._3 Experiment 3: A1C1 3 f o l l o w i n g HCl On 21 August, 1982 a 3 day experiment was s t a r t e d on the sou t h branch of M a y f l y Creek ( F i g . 2.2). A l t h o u g h t h i s s i t e had a h i s t o r y of i n t e r m i t t e n t a c i d i f i c a t i o n , the p r e v i o u s d o s i n g 48 Ta b l e 3.4. Water C h e m i s t r y : Experiment 2 Parameter D i s s o l v e d C o n c e n t r a t i o n C o n t r o l S i t e (1) E x p e r i m e n t a l S i t e (2) Mean SD (a n = 2 Mean SD n = 2 pH A l U g/L) Ca (mg/L) CI (mg/L) Mg (mg/L) K (mg/L) Na (mg/L) a l k a l i n i t y (as CaC0 3) 7.0 31 .0 2.40 0.62 0.32 0.13 1 .07 7.11 0.11 0.15 0.13 0.03 0.12 5 40 2 3 9 2 61 ,76 0.47 0.11 23 1 4 6.9 0.42 0.10 0.02 0.004 (a P o o l e d 25,26 Aug. v a l u e s . t r i a l ended on 11 August. In the i n t e r v e n i n g p e r i o d a r a i n f a l l event caused d i s c h a r g e t o i n c r e a s e s u b s t a n t i a l l y (see F i g . 3.5), p r o v i d i n g an o p p o r t u n i t y f o r r e - c o l o n i z a t i o n by b e n t h i c i n v e r t e b r a t e s . Stream water a c i d i t y a t the c o n t r o l s i t e on the date of t h i s experiment was pH 6.8. Dos i n g began a t 0815 h w i t h a h y d r o c h l o r i c a c i d s o l u t i o n (see S e c t . B.1) which was c o n t i n u o u s l y added u n t i l 0810 h on 23 August. Throughout t h i s p e r i o d pH 5.9 was m a i n t a i n e d a t s i t e 3, 10m below the d o s i n g s t a t i o n . At 0815 h on the 23 r d , HC1 was r e p l a c e d by an A1C1 3 s o l u t i o n and the a d d i t i o n r a t e i m m e d i a t e l y a d j u s t e d t o m a i n t a i n pH 5.9 (mean H +=1.43 X 10~ 6 mol/L, SD=0.85, n = 3 l ) . Aluminum a d d i t i o n c o n t i n u e d a t t h i s r a t e u n t i l 1630 h a t which time the experiment was t e r m i n a t e d . T h i s experiment was d e s i g n e d t o t e s t f o r t h e added e f f e c t of aluminum on a n i m a l s a l r e a d y exposed t o a c i d i f i c a t i o n . Thus, b e f o r e a d d i n g A1C1 3 i t was n e c e s s a r y t o d e s c r i b e r e s i d u a l b i o t i c r e s p o n s e s t o 48 h HC1 d o s i n g . As a r e s u l t , d r i f t i n g 49 i n v e r t e b r a t e s were sampled i m m e d i a t e l y p r i o r t o a d d i n g A1C1 3, and t h e r e a f t e r u n t i l d o s i n g ended. Samples were c o l l e c t e d a t s i t e 1 ( c o n t r o l ) , a t the downstream end of a p o o l ( s i t e 3 ) , and below a r i f f l e ( s i t e 4) (see F i g . 2.2). _3.J__._3.Ji_ B i o l o g i c a l response Immediately p r i o r t o ad d i n g aluminum, t o t a l d r i f t d e n s i t y a t s i t e s 3 and 4 was r o u g h l y an o r d e r - o f - m a g n i t u d e h i g h e r than a t s i t e 1, presumably i n response t o 48 h HCl exposure ( F i g . 3.10a). With the e x c e p t i o n of Ephemeroptera, H y d r a c a r i n a , and Simu l i u m , d r i f t d e n s i t y f o r a l l o t h e r groups was h i g h e r i n the e x p e r i m e n t a l stream s e c t i o n . For compar i s o n , i n the p r e v i o u s e x p e r i m e n t s a l l groups except h a r p a c t a c o i d copepods and P l e c o p t e r a responded t o H C l , A1C1 3, or b o t h . F o l l o w i n g s u b s t i t u t i o n of A1C1 3 f o r HCl as the source of a c i d i t y , t he t o t a l number of a n i m a l s d r i f t i n g a t the c o n t r o l s t a t i o n ( s i t e 1) remained r e l a t i v e l y c o n s t a n t (=72.9 a n i m a l s / 1 0 " L) w h i l e numbers caught a t the p o o l and p o s s i b l y the r i f f l e s i t e i n c r e a s e d ( T able 3.5). In t h i s experiment mean d r i f t d e n s i t y a t s i t e 4 was r o u g h l y 4 X h i g h e r than i n the A1C1 3 e x p e r i m e n t , and >10 X h i g h e r than i n the HCl e x p e r i m e n t . At the r i f f l e s i t e , d r i f t d e n s i t y r o s e s l o w l y , but s t e a d i l y over 6 or more h o u r s . D i f f e r e n c e i n response between the two h a b i t a t s ( s i t e s 3 and 4) i s c l e a r l y e v i d e n t f o r Ephemeroptera (not s o r t e d t o s i z e ) , where t h e r e was no added response t o aluminum a t s i t e 3 but a marked, and immediate r i s e i n d r i f t d e n s i t y a t s i t e 4 5 0 EXPERIMENT 3 TOTAL DRIFT EPHEMEROPTERA B 0600 0800 1000 1200 HOUR 1 400 1600 F i g u r e 3.10a,b. T o t a l and Ephemeroptera D r i f t Response t o A1C1 3 f o l l o w i n g 48 h H C l , pH 5.9. • S i t e 1. n S i t e 3. • S i t e 4. HCl added from 0815 h 21 August u n t i l 0810 h 23 August; A1C1 3 added from 0815 h u n t i l 1630 h 23 August 1982. 51 T a b l e 3.5. D r i f t Response t o A1C1 3 f o l l o w i n g HCl D r i f t d e n s i t y ( a n i m a l s / 1 0 " L) C o n t r o l S i t e (1 ) P o o l S i t e (3) R i f f l e S i t e (4) Taxon Mean SD n Mean SD n Mean SD n Ephem 4.6 2.7 10 63.0 27.4 10 248.0 251.7 10 Ch i ron 56.2 29.2 10 485.5 322. 1 10 1042. 1 644.5 10 T r i c h o p 2.1 1 .3 10 25.9 28.4 1 0 31.3 36.3 10 Hydrac 5.0 1 .8 10 35.8 55.2 10 82.6 61.2 10 Harpact 4.2 4.5 1 0 18.1 16.7 10 38.7 30.6 1 0 Simulium 0.3 0.5 1 0 0 - 1 0 2.2 3.6 1 0 P l e c o p t 0.5 1 .0 10 8.0 7.6 10 10.6 18.5 10 ( F i g . 3.10b). In f a c t , peak d r i f t d e n s i t i e s o b s e r v e d f o r Ephemeroptera a t s i t e 4 (> 500 a n i m a l s / 1 0 " L) are the h i g h e s t ever r e c o r d e d a t M a y f l y Creek, r e g a r d l e s s of s i t e . Mean Ephemeroptera d r i f t d e n s i t y a t the c o n t r o l s i t e was stea d y a t 4.6 anim a l s / 1 0 " L. The immediate response r e c o r d e d here was s i m i l a r t o t h a t observed i n the A1C1 3 experiment,•and d i f f e r e d from the d e l a y e d response seen when HCl was added. Immediately a f t e r i n t r o d u c i n g the aluminum c h l o r i d e s o l u t i o n , c h i r o n o m i d d r i f t d e n s i t y a t s i t e 4 i n c r e a s e d s h a r p l y and c o n t i n u e d t o r i s e u n t i l 2 h a f t e r d o s i n g began when a peak of > 1500 a n i m a l s / 1 0 " L was reached. (Fig.. 3. 11a). T h i s peak was f o l l o w e d by a slow d e c l i n e i n d r i f t d e n s i t y over the next 6 h. At the end of the exper i m e n t , c h i r o n o m i d d r i f t d e n s i t y a t s i t e 4 had n e a r l y r e t u r n e d t o pre-aluminum l e v e l s . In n e i t h e r of the two p r e v i o u s e x p e r i m e n t s had such h i g h d r i f t d e n s i t i e s been r e c o r d e d f o r c h i r o n o m i d s , but the response r a p i d i t y i n t h i s experiment (3) was s i m i l a r t o t h a t d u r i n g the HCl e x p e r i m e n t . Chironomids a t s i t e 3 responded v e r y d i f f e r e n t l y from those a t s i t e 4 ( F i g . 3.11a). Below the p o o l ( s i t e 3 ) , t h e r e was a p p a r e n t l y a 6 h d e l a y i n r e s p o n s e , and peak d r i f t d e n s i t y (^900 5 2 EXPERIMENT 3 CHIRONOMIDAE TRICHOPTERA 0600 0800 1000 1200 HOUR 1 400 1600 F i g u r e 3.11a,b. Chironomidae and T r i c h o p t e r a D r i f t i n Response t o A1C1 3 F o l l o w i n g 48 h H C l , pH 5.9. • S i t e 1. n S i t e 3. • S i t e 4. HCl added from 0815 h 21 August u n t i l 0810 h 23 August; A1C1 3 added from 0815 h u n t i l 1630 h 23 August 1982. 53 a n i m a l s / 1 0 1 1 L) was lower than t h a t r e c o r d e d a t s i t e 4. Ch i r o n o m i d d r i f t d e n s i t y a t s i t e 3 then d e c r e a s e d u n t i l the experiment was t e r m i n a t e d . Throughout the e x p e r i m e n t a l p e r i o d , mean d r i f t d e n s i t y a t s i t e 1 was 56.2 a n i m a l s / 1 0 * L. A g a i n , peak d r i f t d e n s i t y here was g r e a t e r than r e c o r d e d i n e i t h e r the HCl or A1C1 3 e x p e r i m e n t s . However, the d e l a y e d response was s i m i l a r i n t i m i n g t o t h a t o b s e r v e d i n the A1C1 3 e x p e r i m e n t . T r i c h o p t e r a from both s i t e s 3 and 4 responded t o the added aluminum, but o n l y a f t e r r o u g h l y a 6-hour d e l a y ( F i g . 3.11b), as was the c a s e i n the A1C1 3 e x p e r i m e n t . A g a i n , responses a t s i t e s 3 and 4 d i f f e r e d . Below the r i f f l e , d r i f t d e n s i t y remained low u n t i l a g r e a t l y i n c r e a s e d peak was r e c o r d e d r o u g h l y 6 h . a f t e r d o s i n g began. T h i s was f o l l o w e d by a s h a r p d e c l i n e i n d r i f t d e n s i t y . At s i t e 3, below the p o o l , t h e r e was a l s o =6 h d e l a y i n re s p o n s e o b s e r v e d , but a f t e r the i n i t i a l i n c r e a s e , d r i f t d e n s i t y t h e r e c o n t i n u e d t o r i s e u n t i l t h e experiment ended. At each s i t e , maximum d r i f t d e n s i t y r e c o r d e d was >5 X h i g h e r than had been p r e v i o u s l y r e c o r d e d i n e i t h e r the HCl or A1C1 3 e x p e r i m e n t s . At the c o n t r o l s i t e , d r i f t d e n s i t y h e l d s t e a d y a t around 2 a n i m a l s / 1 0 " L. H y d r a c a r i n a a l s o e x h i b i t e d a d e l a y e d response (=6 h ) , as obs e r v e d i n t h e A1C1 3 experiment ( F i g . 3.12a). At both s i t e s 3 and 4, t h e r e was a marked i n c r e a s e i n d r i f t d e n s i t y a f t e r about 6 hours t o a l e v e l r o u g h l y 10 X h i g h e r than i n e x p e r i m e n t s 1 and 2. Even though e a r l i e r s t u d i e s a t t h i s s i t e had shown t h a t H y d r a c a r i n a d r i f t i n i n c r e a s i n g numbers, p r i o r t o sunset (see S e c t . A.2.2), t h e r e was no c o r r e s p o n d i n g i n c r e a s e i n the 54 c o n t r o l n e t s where mean d r i f t d e n s i t y remained a t 5 a n i m a l s / 1 0 " L. Thus, the d e l a y e d i n c r e a s e i n H y d r a c a r i n a d r i f t a f t e r A l C l 3 a d d i t i o n i s a t t r i b u t e d t o the t r e a t m e n t . Data f o r h a r p a c t a c o i d copepods c o l l e c t e d a t s i t e 4 suggest t h e r e was an immediate, but b r i e f , response t o i n c r e a s e d aluminum c o n c e n t r a t i o n s ( F i g . 3.12b). Peak d r i f t d e n s i t y r e c o r d e d was > 75 an i m a l s / 1 0 " L, compared w i t h a v a l u e of =05 a n i m a l s / 1 0 " L a t t h i s s i t e p r i o r t o s w i t c h i n g from HCl t o A1C1 3. Mean d r i f t d e n s i t y a t s i t e 3 (18.1 a n i m a l s / 1 0 " L) was h i g h e r than a t the c o n t r o l s i t e (4.2 a n i m a l s / 1 0 " L ) , but t h e r e was no e v i d e n c e of an aluminum response a t s i t e 3. P r e v i o u s l y , h a r p a c t a c o i d copepods had not been encountered r e s p o n d i n g t o e i t h e r A1C1 3 or H C l . P r i o r - t o d o s i n g the south branch of M a y f l y Creek w i t h aluminum, S i m u l i u m were seldom c a p t u r e d i n the d r i f t n e t s , even at s i t e s 3 and 4 a f t e r 48 h c o n t i n u o u s exposure t o HCl ( F i g . 3.13a). However, a f t e r the a c i d source was s w i t c h e d t o A 1 C 1 3 , over the next 8 hours t h e r e was a d r a m a t i c b u i l d u p i n S i m u l i u m d r i f t d e n s i t y below the r i f f l e ( s i t e 4 ) , f i n a l l y r e a c h i n g a peak of > 4 a n i m a l s / 1 0 " L. T h i s compared w i t h a mean of 0.3 a n i m a l s / 1 0 " L a t the c o n t r o l s i t e . D u r i n g the e x p e r i m e n t a l p e r i o d , no Simulium were ever c a p t u r e d a t s i t e 3. Simulium were absent from v i r t u a l l y a l l samples t a k e n d u r i n g b o t h the HCl and A1C1 3 e x p e r i m e n t s . W i t h i n 2 hours a f t e r aluminum was added, P l e c o p t e r a (not s o r t e d by s i z e ) d r i f t d e n s i t i e s a t s i t e 4 r o s e t o > 30 a n i m a l s / 1 0 " L compared w i t h a mean d r i f t d e n s i t y of 0.5 5 5 EXPERIMENT 3 HYDRACARINA F i g u r e 3.12a,b. H y d r a c a r i n a and H a r p a c t a c o i d a D r i f t Response t o A1C1 3 F o l l o w i n g 48 h H C l , pH 5.9. • S i t e 1. n S i t e 3. • S i t e 4. HCl added from 0815 h 21 August u n t i l 0810 h 23 August; A1C1 3 added from 0815 h u n t i l 1630 h 23 August 1982. 56 a n i m a l s / 1 0 " L a t the c o n t r o l s t a t i o n ( F i g . 3.13b). However, by the next s a m p l i n g p e r i o d , d r i f t d e n s i t y had r e t u r n e d t o p r e -aluminum l e v e l s . There may a l s o have been a s i m i l a r , but l e s s pronounced, response a t s i t e 3. P l e c o p t e r a d r i f t d e n s i t y a t s i t e 1 remained low and n e a r l y c o n s t a n t (mean = 0.5 a n i m a l s / 1 0 " L) throughout the t r i a l p e r i o d . P l e c o p t e r a had not responded t o e i t h e r HCl or A1C1 3 when a d m i n i s t e r e d s e p a r a t e l y . 3_.__.3_._2 P h y s i c a l - c h e m i c a l c o n d i t i o n s As a r e s u l t of a r a i n f a l l event 10 days p r e v i o u s l y , d i s c h a r g e a t M a y f l y Creek on t h i s d a t e was s l i g h t l y above base-f l o w ( F i g . 3.5b). In a d d i t i o n t o c o n t i n u o u s l y m o n i t o r i n g pH i n the stream, a c i d i t y measurements were made f o r . w a t e r s 0.5 m below the s u b s t r a t e / w a t e r i n t e r f a c e . W i t h i n 15 min a f t e r a c i d i f i c a t i o n began i n o v e r l y i n g w a t e r s , a decrease i n pH was d e t e c t e d a t d e p t h . No o t h e r c h e m i c a l a n a l y s e s are a v a i l a b l e f o r t h i s e x periment. 3.2 R e s u l t s of L a b o r a t o r y E x p e r i m e n t s w i t h C l ~ Experiments 4 and 5 were c a r r i e d out i n August, 1985, t o e v a l u a t e the impact, i f any, of added c h l o r i d e i o n s on d r i f t d e n s i t y . Ephemeroptera nymphs and c h i r o n o m i d l a r v a e were exposed t o c o m b i n a t i o n s of two H + and C l " i o n c o n c e n t r a t i o n s , and responses t o t r e a t m e n t s were e v a l u a t e d by comparing numbers of a n i m a l s e m i g r a t i n g from each l a b o r a t o r y stream c h a n n e l . EXPERIMENT 3 SIMULIUM 57 0600 0800 1000 1200 1400 1600 HOUR F i g u r e 3.13a,b. Simulium and P l e c o p t e r a D r i f t Response t o A1C1 3 F o l l o w i n g 48 h H C l , pH 5.9. • S i t e 1. n S i t e 3. • S i t e 4. HCl added from 0815 h 21 August u n t i l 0810 h 23 August; AICI3 added from 0815 h u n t i l 1630 h 23 August 1982. 58 3_._2._1_ P h y s i c a l - c h e m i c a l c o n d i t i o n s D u r i n g t h e s e e x p e r i m e n t s , adding c h o l i n e c h l o r i d e had no e f f e c t on stream water pH, but d i d r a i s e C l " c o n c e n t r a t i o n s by a f a c t o r of 5 (Table 3.6). In both e x p e r i m e n t s , pH f o r the c h a n n e l s r e c e i v i n g a c i d s was n e a r l y i d e n t i c a l . As w e l l , b o th the HCl and c h o l i n e c h l o r i d e a d d i t i o n s r a i s e d C l " by r o u g h l y the same amount. Water and a i r te m p e r a t u r e s were 15.5°C and 13°C, r e s p e c t i v e l y . T a b l e 3.6. Water C h e m i s t r y d u r i n g C h l o r i d e Experiments Ephemeroptera Chironomidae Mean (n=3 ) Mean (n=3) Treatment pH (mq/L) C I -SD £H C l " (mq/L) SD C o n t r o l 6.2 1 .6 0.1 6.9 1.5 0 C h o i i n e C h l o r i d e 6.2 5.3 0.5 6.9 5.1 1.1 H 2SO, 5.7 1 .5 0.1 6.2 1.5 0.9 HCl 5.7 5.5 0.1 6. 1 5.4 0.4 3.2.2 B i o l o g i c a l response Ephemeroptera nymphs used i n t h i s experiment were a l l < 2 mm i n l e n g t h and were s e n s i t i v e i n d i v i d u a l s , as e v i d e n c e d by t h e i r d r i f t i n response t o aluminum a d d i t i o n s used t o c o l l e c t them i n the f i e l d . A f t e r e x p o s i n g the m a y f l y nymphs t o t e s t c o n d i t i o n s f o r 3 h no s i g n i f i c a n t response was d e t e c t e d t o 59 e i t h e r i n c r e a s e d c h l o r i d e (F1,8= 0.63, p >0.4) or hydrogen i o n (F1,8= 0.50, p=1.0) c o n c e n t r a t i o n s . As w e l l , no s i g n i f i c a n t i n t e r a c t i o n was d e t e c t e d between pH and c h l o r i d e (F1,8= 0.07, p=0.8). However, the b l o c k e f f e c t neared s i g n i f i c a n c e (F3,5= 7.83, p=0.06). F a i l u r e of i n d i v i d u a l s t o respond t o e i t h e r HCl or H 2SO u s t r o n g l y s u g gests t h a t d r i f t i n g b e h a v i o r o b s e r v e d i n the f i e l d was not due t o de p r e s s e d pH, but r a t h e r t o some o t h e r f a c t o r - - most p r o b a b l y e l e v a t e d aluminum c o n c e n t r a t i o n . C h i r o n o m i d l a r v a e were exposed t o the t e s t c o n d i t i o n s f o r 2.75 h. At the end of t h i s t i m e , no s i g n i f i c a n t e f f e c t due t o CI" (F1,8= 1.63, p=0.5), pH (F1,8= 0, p=1.0), or an i n t e r a c t i o n between pH and c h l o r i d e (F1,8= 0.06, p=1.0) was d e t e c t e d . As w e l l , t h e r e were no s i g n i f i c a n t d i f f e r e n c e s between b l o c k s of stream c h a n n e l s (F3,5= 0.08, P=1.0). Because many of the c h i r o n o m i d l a r v a e used i n t h i s experiment were > 2 mm, they may have been l e s s s e n s i t i v e t o the t r e a t m e n t s than were those i n d i v i d u a l s o b s e r v e d r e s p o n d i n g i n the e a r l i e r f i e l d e x p e r i m e n t s . C h l o r i d e i o n l e v e l s measured i n the d e c h l o r i n a t e d water s u p p l y were r o u g h l y t h r e e t i m e s h i g h e r than i n the streams from which t h e s e a n i m a l s had been c o l l e c t e d . C I " i s a breakdown byproduct of water c h l o r i n a t i o n p r o c e s s e s (Robert J o n e s , G.V.R.D., p e r s . comm.). N e v e r t h e l e s s , t h i s e l e v a t e d c h l o r i d e c o n c e n t r a t i o n appears not t o a d v e r s e l y a f f e c t growth i n a n i m a l s from streams i n the U.B.C. R e s e a r c h F o r e s t , s i n c e t hey can be s u c c e s s f u l l y r e a r e d t o a d u l t h o o d i n these; d e c h l o r i n a t e d w a t e r s w i t h m i n i m a l m o r t a l i t y (John R i c h a r d s o n , I.A.R.E., p e r s . 60 c omm.) . _3._3 Summary P r i o r t o i n t r o d u c i n g c h e m i c a l p e r t u r b a t i o n s , d i e l i n v e r t e b r a t e d r i f t p a t t e r n s a t M a y f l y Creek were s i m i l a r t o thos e r e c o r d e d many times a t o t h e r s i t e s t hroughout N o r t h America (Waters 1972). Large Ephemeroptera, l a r g e Chironomidae ( D i p t e r a ) , and H y d r a c a r i n a a l l e x h i b i t e d i n c r e a s e d d r i f t a c t i v i t y a s s o c i a t e d w i t h low l i g h t l e v e l s . For the r e m a i n i n g g roups, d r i f t d e n s i t y remained r e l a t i v e l y c o n s t a n t through t i m e . At s i t e 1 background d r i f t d e n s i t y was around 70 a n i m a l s / 1 0 " L, w i t h t h r e e - q u a r t e r s of each d r i f t sample composed of s m a l l c h i r o n o m i d s . T o g e t h e r , s m a l l m a y f l i e s (Ephemeroptera), water m i t e s ( H y d r a c a r i n a ) , and h a r p a c t a c o i d copepods (Copepoda) co m p r i s e d an a d d i t i o n a l 20% of t o t a l background d r i f t numbers. D u r i n g the HCl experiment ( 2 ) , n e i t h e r l a r g e Ephemeroptera, H y d r a c a r i n a , h a r p a c t a c o i d copepods nor any s i z e s of P l e c o p t e r a responded t o HCl a d d i t i o n s . However, T r i c h o p t e r a and c h i r o n o m i d s of a l l s i z e s responded i m m e d i a t e l y . Meanwhile, d r i f t d e n s i t y f o r s m a l l Ephemeroptera g r a d u a l l y i n c r e a s e d , r e a c h i n g a maximum 6 h l a t e r . There was a l s o a weak response r e c o r d e d f o r Si m u l i u m . Over the c o u r s e of experiment 2, mean d r i f t d e n s i t y a t s i t e 2 was n e a r l y 3 X h i g h e r than a t s i t e 1. Immediately a f t e r aluminum was added i n experiment 1, d r i f t d e n s i t y doubled i n the e x p e r i m e n t a l stream s e c t i o n , w i t h most of the i n c r e a s e due t o a sudden e n t r y i n t o the water column by s m a l l Ephemeroptera. U n t i l A1C1 3 d o s i n g c e a s e d , d r i f t d e n s i t y 61 f o r t h i s group remained e l e v a t e d . S i x hours a f t e r the tr e a t m e n t began, s m a l l c h i r o n o m i d s , c a d d i s f l i e s ( T r i c h o p t e r a ) , and H y d r a c a r i n a began t o e n t e r the water column i n i n c r e a s i n g numbers c a u s i n g the t o t a l d r i f t d e n s i t y t o a g a i n d o u b l e . There was a l s o weak evi d e n c e s u g g e s t i n g some l a r g e r m a y f l i e s and c h i r o n o m i d s responded t o t h i s t r e a t m e n t . No s u b s t a n t i a l response was r e c o r d e d f o r h a r p a c t a c o i d copepods, Simulium or s t o n e f l i e s ( P l e c o p t e r a ) . D u r i n g aluminum a d d i t i o n s , mean d r i f t d e n s i t y i n the e x p e r i m e n t a l stream s e c t i o n was more than 6 X h i g h e r than a t the c o n t r o l s i t e . Peak d r i f t d e n s i t y r e c o r d e d a t s i t e 2 d u r i n g aluminum a d d i t i o n s was more than t w i c e t h a t o b s e r v e d a t the same pH d u r i n g experiment 2 ( H C l ) . D u r i n g experiment 3, a l l groups responded t o A l 3 + , a l t h o u g h t h e r e was o n l y a moderate, d e l a y e d response by P l e c o p t e r a , compared w i t h a s t r o n g , w e l l - d e f i n e d response by a l l o t h e r groups. P r i o r t o A1C1 3 d o s i n g , P l e c o p t e r a d r i f t r a t e s were s t i l l e l e v a t e d a f t e r 48 h of HCl exposure; as w e l l , some T r i c h o p t e r a and h a r p a c t a c o i d copepods were a p p a r e n t l y s t i l l r e s p o n d i n g t o H C l . A f t e r A1C1 3 d o s i n g began, h a r p a c t a c o i d s and a l l s i z e s of Ephemeroptera and Chironomidae responded i m m e d i a t e l y , but then d r i f t d e n s i t y began t o d e c l i n e , perhaps due t o e x h a u s t i o n of b e n t h i c p o p u l a t i o n s . S t a r t i n g 6 h a f t e r A1C1 3 d o s i n g began, I a l s o o b s e r v e d a s u b s t a n t i a l i n c r e a s e i n d r i f t d e n s i t y of T r i c h o p t e r a , H y d r a c a r i n a , and Simulium. Compared w i t h c o n t r o l s i t e 1, mean d r i f t d e n s i t i e s were >8 X and 20 X h i g h e r a t s i t e s 3 and 4, r e s p e c t i v e l y . Peak d r i f t d e n s i t i e s d u r i n g experiment 3 were r o u g h l y 10 X h i g h e r than i n 62 the A1C1 3 experiment. 63 CHAPTER 4. GENERAL DISCUSSION 4.__ B i o t a 4_.J_.J_ E v a l u a t i o n of hypotheses Hypothes i s _]_: Some l o t i c i n v e r t e b r a t e s r e s i d i n g i n  g e o c h e m i c a l l y s e n s i t i v e a r e a s of B.C. can d e t e c t and  respond t o d i s s o l v e d aluminum i o n s . P r o b a b l y the c l e a r e s t e v i d e n c e s u p p o r t i n g t h i s h y p o t h e s i s i s found i n the av o i d a n c e b e h a v i o r shown by Ephemeroptera when exposed t o A1C1 3 a d d i t i o n s d u r i n g b o t h e x p e r i m e n t s 1 and 3. In each case t h e r e was an immediate i n c r e a s e i n d r i f t d e n s i t y which c o n t r a s t e d s h a r p l y w i t h the s m a l l e r and d e l a y e d response t o HCl (experiment 2 ) . Chironomids a l s o responded immediately t o e l e v a t e d A l 3 + c o n c e n t r a t i o n s i n experiment 3; t h i s r esponse, however, may have r e s u l t e d from s e n s i t i z a t i o n by p r i o r HCl exposure s i n c e t h e i r response t o e l e v a t e d A l 3 + i n experiment 1 was much s l o w e r . Other a n i m a l s r e s p o n d i n g t o aluminum t r e a t m e n t s a l l d i d so a f t e r some time d e l a y ( u s u a l l y =6 h ) , s u g g e s t i n g t h e s e responses were not the d i r e c t r e s u l t of d e t e c t i o n . H a l l et a l . (1985b) a l s o r e p o r t t h a t i n t h e i r f i e l d e x p e r i m e n t s some i n v e r t e b r a t e s responded w i t h i n 15 min a f t e r aluminum c o n c e n t r a t i o n s were e l e v a t e d . C o n t r a r y t o e x p e c t a t i o n s , b o t h c h i r o n o m i d s and T r i c h o p t e r a responded almost i m m e d i a t e l y t o HCl a d d i t i o n s i n experiment 2. Because n e i t h e r group responded r a p i d l y t o aluminum a d d i t i o n s i n 64 experiment 1 (nor d i d T r i c h o p t e r a respond t o aluminum i n experiment 3 ) , these a n i m a l s p r o b a b l y can d e t e c t and respond d i r e c t l y t o e l e v a t e d H + c o n c e n t r a t i o n s . Based upon these e x p e r i m e n t a l r e s u l t s I ac c e p t the h y p o t h e s i s t h a t some s t r e a m - d w e l l i n g i n v e r t e b r a t e s can d e t e c t and respond t o e l e v a t e d c o n c e n t r a t i o n s of d i s s o l v e d aluminum. H y p o t h e s i s 2: Not a l l taxonomic groups respond s i m i l a r l y  t o e l e v a t e d d i s s o l v e d aluminum c o n c e n t r a t i o n s . Taken t o g e t h e r , r e s u l t s of a l l t h r e e f i e l d e x p e r i m e n t s c l e a r l y show a d i v e r s i t y of responses by d i f f e r e n t taxonomic groups t o e l e v a t e d d i s s o l v e d aluminum c o n c e n t r a t i o n s . Even among a q u a t i c i n s e c t s t h e r e was c o n s i d e r a b l e v a r i a t i o n i n r e s p o n s e , w i t h the l e s s r e a c t i v e P l e c o p t e r a and Simulium b e h a v i n g v e r y d i f f e r e n t l y from s e n s i t i v e c h i r o n o m i d s and Ephemeroptera. There was a l s o n o n - u n i f o r m i t y of response w i t h i n n o n - i n s e c t o r d e r s , w i t h H y d r a c a r i n a e x h i b i t i n g a much g r e a t e r response t o d i s s o l v e d aluminum than d i d h a r p a c t a c o i d copepods. Thus, the e v i d e n c e s u p p o r t s t h i s h y p o t h e s i s . H y p o t h e s i s 3: Some l o t i c i n v e r t e b r a t e s a re r e l a t i v e l y more  s e n s i t i v e t o aluminum than t o hydrogen i o n s . To demonstrate t h a t stream i n v e r t e b r a t e s a r e r e l a t i v e l y more s e n s i t i v e t o aluminum than t o hydrogen i o n s r e q u i r e s e v i d e n c e t h a t response v a r i e s w i t h A l 3 + c o n c e n t r a t i o n a t any g i v e n H + c o n c e n t r a t i o n . E v i d e n c e t h a t s m a l l Ephemeroptera were, i n d e e d , more r e s p o n s i v e t o e l e v a t e d A l 3 + than t o H + i o n c o n c e n t r a t i o n s may be found by comparing r e s u l t s o b t a i n e d in- the-HCl experiment (2) w i t h t h o s e i n experiment 1. For T r i c h o p t e r a 65 and s m a l l c h i r o n o m i d s , though, the r e v e r s e was t r u e ; t h e s e a n i m a l s were r e l a t i v e l y more s e n s i t i v e t o e l e v a t e d H + than t o A l 3 + i o n c o n c e n t r a t i o n s . E x p o s i n g l o t i c i n v e r t e b r a t e s t o a c i d f o r 48 h i n experiment 3 i n c r e a s e d s e n s i t i v i t y of s e v e r a l groups t o d i s s o l v e d aluminum. C h i r o n o m i d s , Simulium, and P l e c o p t e r a f o r example, were a l l more s e n s i t i v e t o aluminum i n experiment 3 than i n experiment 1. In s i m i l a r aluminum a d d i t i o n e x p e r i m e n t s c o n d u c t e d i n New Hampshire, H a l l et a l . (1985b) showed t h a t l o w e r i n g stream water t o pH 5.25-5.5 had l i t t l e e f f e c t on d r i f t d e n s i t y ; however, d r i f t d e n s i t y i n c r e a s e d n o t i c e a b l y a f t e r aluminum c o n c e n t r a t i o n s were i n c r e a s e d a t the same pH. These r e s u l t s c o r r o b o r a t e those p r e s e n t e d i n t h i s t h e s i s ; c o n s e q u e n t l y , I accept t h i s h y p o t h e s i s . H y p o t h e s i s 4_: For " s e n s i t i v e " i n v e r t e b r a t e s , e a r l y i n s t a r s  a re more s e n s i t i v e t o i n c r e a s e d A l 3 + and H + i o n  c o n c e n t r a t i o n s than a r e l a t e r i n s t a r s . I f e a r l y i n s t a r s ( s m a l l i n d i v i d u a l s ) of a g i v e n taxon e n t e r the d r i f t more r a p i d l y than l a t e r i n s t a r s ( l a r g e r i n d i v i d u a l s ) i n response t o a s p e c i f i e d t r e a t m e n t , t h i s would be good e v i d e n c e s u p p o r t i n g h y p o t h e s i s 4. U n f o r t u n a t e l y , because I was unable t o t a x o n o m i c a l l y i d e n t i f y e a r l y i n s t a r s , I c o u l d not determine i f l a r g e and s m a l l i n d i v i d u a l s came from the same p o p u l a t i o n . However, e v i d e n c e c o l l e c t e d from t h e s e e x p e r i m e n t s suggests t h a t , of the t h r e e groups d i s t i n g u i s h e d by s i z e , h y p o t h e s i s 4 c o u l d h o l d t r u e f o r o n l y o n e — E p h e m e r o p t e r a , but not f o r Chironomidae and P l e c o p t e r a . C o n t r a r y t o e x p e c t a t i o n s , 66 t h e r e was a n o t i c e a b l e d i f f e r e n c e a c c o r d i n g t o s i z e i n Ephemeroptera o n l y i n experiment 2, w i t h s m a l l e r a n i m a l s e n t e r i n g the d r i f t sooner a f t e r exposure than l a r g e r ones i n r e s p o n s e t o H C l . A c c o r d i n g t o t h i s c r i t e r i o n , P l e c o p t e r a and c h i r o n o m i d s f a i l e d t o show g r e a t e r s e n s i t i v i t y among s m a l l e r s i z e c l a s s e s . A l t h o u g h l a b o r a t o r y t e s t s have shown t h a t s e n s i t i v i t y t o low pH and e l e v a t e d aluminum c o n c e n t r a t i o n v a r i e s w i t h l i f e s t a g e f o r some f i s h s p e c i e s ( e.g. Baker and S c h o f i e l d 1982), t h e r e a r e few s i m i l a r r e s u l t s a v a i l a b l e f o r f r e s h w a t e r i n v e r t e b r a t e s . I t i s known, though, t h a t d u r i n g e c d y s i s and emergence, m o r t a l i t y can be e s p e c i a l l y h i g h f o r a n i m a l s i n a c i d w a t e r s ( B e l l 1971; Raddum and S t e i g e n 1981). Thus, t h e r e i s c u r r e n t l y i n s u f f i c i e n t e v i d e n c e t o e i t h e r s u p p o r t or r e j e c t t h i s h y p o t h e s i s . H y p o t h e s i s ; I n c r e a s e d d r i f t d e n s i t y o b s e r v e d i n f i e l d  e x p e r i m e n t s r e s u l t e d from response t o e l e v a t e d C l '  c o n c e n t r a t i o n s . T h i s h y p o t h e s i s was not s u p p o r t e d by s h o r t - t e r m (3 h) l a b o r a t o r y t e s t s w i t h e i t h e r c h i r o n o m i d l a r v a e or Ephemeroptera nymphs. In l a b o r a t o r y t e s t s e x p o s i n g a q u a t i c i n v e r t e b r a t e s t o HCl and H 2 S 0 4 s o l u t i o n s at the same H + c o n c e n t r a t i o n , i t has been shown t h a t t o x i c e f f e c t s a r e more c l o s e l y a s s o c i a t e d w i t h pH than w i t h the a n i o n c o n c e n t r a t i o n ( G a u f i n 1973). Whether d r i f t b e h a v i o r , as opposed t o t o x i c i t y , would be r e l a t i v e l y u n a f f e c t e d by a n i o n c o n c e n t r a t i o n s i s unknown. Over a l o n g e r e x p o s u r e p e r i o d i t i s s t i l l p o s s i b l e t h a t a n i m a l s would respond 67 a l t h o u g h , based upon f i e l d e x p e r i m e n t s comparing a n i m a l responses t o HCl and H 2SO« a d d i t i o n s , H a l l e t a l . (1985b) a l s o c o n c l u d e d t h a t e l e v a t e d C I" i o n c o n c e n t r a t i o n s p l a y e d no r o l e i n observ e d d r i f t r e s p o n s e s . T o g e t h e r , t h e s e r e s u l t s l e a d me t o r e j e c t the h y p o t h e s i s t h a t observed i n c r e a s e d d r i f t d e n s i t y was caused by e l e v a t e d C I" c o n c e n t r a t i o n s . _4.J_._2 B e h a v i o r a l response r a t e s A c i d p r e c i p i t a t i o n i s a problem i n which an u n d e r s t a n d i n g of r a t e s i s e s s e n t i a l . The r e a c t i o n by stream i n v e r t e b r a t e s t o c h e m i c a l p e r t u r b a t i o n s d e s c r i b e d i n my s t u d i e s can be d i v i d e d i n t o a t l e a s t t h r e e major c a t e g o r i e s , based upon response r a t e : (a) no re s p o n s e , (b) d e l a y e d r e s p o n s e , and (c) immediate r e s p o n s e . No response F a i l u r e of i n d i v i d u a l s t o respond by e n t e r i n g the water column can be i n t e r p r e t e d in- a t l e a s t f i v e ways: (1) the c h e m i c a l i s p h y s i o l o g i c a l l y n o n - r e a c t i v e , (2) the s u b s t a n c e i s p r e s e n t i n u n d e t e c t a b l e c o n c e n t r a t i o n s , (3) a n i m a l s succumb w h i l e l o c a t e d i n h a b i t a t s where they cannot be swept i n t o the water column, (4) n e g a t i v e l y buoyant a n i m a l s ( e . g . , c a s e d T r i c h o p t e r a ) a r e unable t o be c a r r i e d by the c u r r e n t , and (5) some a n i m a l s may respond by b u r r o w i n g i n t o the s u b s t r a t e . In e x p e r i m e n t s 1 and 2, P l e c o p t e r a of a l l s i z e c l a s s e s and h a r p a c t a c o i d copepods f a i l e d t o respond t o e i t h e r i n c r e a s e d A l 3 + or H + i o n c o n c e n t r a t i o n s . As w e l l , n e i t h e r l a r g e Ephemeroptera nor H y d r a c a r i n a responded t o a c i d a d d i t i o n s ( e xperiment 2 ) . 68 With the p o s s i b l e e x c e p t i o n of l a r g e P l e c o p t e r a , none of these a n i m a l s i s p a r t i c u l a r l y n e g a t i v e l y buoyant, and a l l a r e found d r i f t i n g under n a t u r a l c o n d i t i o n s a t t h i s s i t e (see S e c t . A.2). C o n s e q u e n t l y , i t i s u n l i k e l y t h a t i n a b i l i t y t o d r i f t p r e v e n t e d a response from b e i n g d e t e c t e d i n t h e s e a n i m a l s . F u r t h e r m o r e , w i t h the p o s s i b l e e x c e p t i o n s of copepods and H y d r a c a r i n a , many of these a n i m a l s a r e t y p i c a l l y found near the b e n t h i c / w a t e r i n t e r f a c e and r o u t i n e l y e n t e r the water column and d r i f t ; presumably, t h e n , t h i s r o u t e was open t o a n i m a l s a t t e m p t i n g t o escape. The absence of a d e t e c t a b l e response can be i n t e r p r e t e d as i n d i c a t i n g e i t h e r t h a t the a p p l i e d c h e m i c a l s were p h y s i o l o g i c a l l y n o n - s t r e s s f u l w i t h i n the time frame t e s t e d , or t h a t these a n i m a l s l a c k the sensory c a p a c i t y t o d e t e c t such m i l d l y e l e v a t e d H + and A l 3 + i o n l e v e l s . I t i s w e l l known t h a t P l e c o p t e r a l a r v a e possess chemoreceptors (Rupprecht and Gnatzy 1974; Kapoor and Z a c h a r i a h 1983). S t i l l , as a group, s t o n e f l i e s a r e c o n s i d e r e d moderately a c i d t o l e r a n t based upon l a b o r a t o r y b i o a s s a y s ( B e l l and Nebeker 1969; B e l l 1971) and f i e l d s t u d i e s ( O t t o and Svensson 1983; Stoner e t a l . 1984; Mackay and Kersey 1985). However, f o l l o w i n g p r o l o n g e d e x p e r i m e n t a l exposure (^  25 days) t o H 2SO„ at pH 4.0 i n N o r r i s Brook, N.H., H a l l e t a l . (1982) d i d observe a s i g n i f i c a n t s h i f t i n d r i f t d e n s i t y f o r t h i s group i n d i c a t i n g a net o u t f l u x of a n i m a l s from the a c i d i f i e d r e g i o n . In experiment 3, I o b s e r v e d a s i m i l a r r e s u l t where t h e r e was evidence s u g g e s t i n g a weak response by r i f f l e s t o n e f l i e s t o e l e v a t e d aluminum. Responding a n i m a l s may have become s e n s i t i z e d t o A l 3 + 69 a f t e r 48 h of HCl exposure. N o n e t h e l e s s , i n headwaters where a c i d d i s t u r b a n c e s f r e q u e n t l y o c c u r , s h r e d d i n g s t o n e f l i e s a r e common ( H a l l e t a l . 1985b). Mackay and Ker s e y (1985) have suggested t h a t s h r e d d e r s may be more t o l e r a n t of i n c r e a s e d a c i d i t y because they a re adapted t o l i v e among d e c a y i n g l e a v e s , where pH may be n a t u r a l l y reduced by o r g a n i c a c i d s . At M a y f l y Creek t h e r e a r e a t l e a s t 13 s p e c i e s of P l e c o p t e r a ( S e c t . A. 1.2.1), most of which appear t o be t o l e r a n t of m i l d l y e l e v a t e d A l 3 + and H + i o n c o n c e n t r a t i o n s (pH 5.9), a t l e a s t f o r s h o r t (< 12 h) time p e r i o d s . In M a y f l y Creek, h a r p a c t a c o i d copepods t y p i c a l l y d r i f t a t a low, but r e l a t i v e l y c o n s t a n t , r a t e (see S e c t . A . 2 ) , and were l a r g e l y u n a f f e c t e d by e l e v a t e d c o n c e n t r a t i o n s of e i t h e r A l 3 + or H +. A l t h o u g h few stream r e s e a r c h e r s use n e t s w i t h a mesh s i z e s m a l l enough t o r o u t i n e l y sample s m a l l c r u s t a c e a n s , F r o s t (1942) d i d f i n d copepods a s s o c i a t e d w i t h mosses i n an a c i d i c stream. As w e l l , i n e a s t e r n N o r t h America ( K e l l e r 1981) and so u t h e r n Norway (Hobaek and Raddum 1980), c a l a n o i d and d i a p t o m i d copepods ar e o f t e n abundant i n a c i d l a k e s . S i n c e h a r p a c t i c o i d copepods feed among d e c a y i n g v e g e t a t i o n ( W i l s o n and Yeatman 1959), they too may be r e g u l a r l y exposed t o e l e v a t e d a c i d i t y . I t i s a l s o p o s s i b l e t h a t a n i m a l s such as h a r p a c t a c o i d s l i v i n g w i t h i n a l a r g e l y o r g a n i c m a t r i x a r e " b u f f e r e d " from e p i s o d i c i n c r e a s e s i n A l 3 + because of the a f f i n i t y aluminum i o n s have f o r b i n d i n g s i t e s on o r g a n i c m a t t e r . The b r i e f i n c r e a s e i n d r i f t d e n s i t y of h a r p t a c o i d copepods d u r i n g the f i r s t s a m p l i n g p e r i o d of experiment 3 was an i s o l a t e d r e s u l t , not r e p e a t e d i n subsequent 70 samples. As such i t may have been a response by a n i m a l s " s e n s i t i z e d " t o A l 3 + , o r , e q u a l l y l i k e l y , t h e s e a n i m a l s were d i s l o d g e d by o t h e r a n i m a l s a t t e m p t i n g t o r e a c h the water column. For l a k e s i n c e n t r a l O n t a r i o , C o l l i n s e t a l . (1981) found t h a t c o m p o s i t i o n of e p i f a u n a l i n s e c t communities was much more s t r o n g l y r e l a t e d t o pH than was the case f o r i n f a u n a l communities. From t h i s i t appears t h a t i n l a k e s some a n i m a l s may use o r g a n i c sediments as a r e f u g e from a c i d i c w a t e r s . However, because of the permeable n a t u r e of some l o o s e l y -a g g r e g a t e d , i n o r g a n i c stream sediments (see W i l l i a m s 1984), i t seems l i k e l y t h a t a c i d i c w a t e r s would, i n t i m e , p e n e t r a t e t o a l l h a b i t a t s s u i t a b l e f o r a e r o b i c i n v e r t e b r a t e s . D e l a y e d response There a r e s e v e r a l p l a u s i b l e mechanisms f o r d e l a y e d d r i f t i n c l u d i n g p h y s i c a l and p h y s i o l o g i c a l c o n s i d e r a t i o n s . S i n c e stream i n v e r t e b r a t e s may be found deep i n the benthos ( W i l l i a m s 1984) or c o n f i n e d w i t h i n l e a f - p a c k s (Cummins 1974), waters of a l t e r e d c h e m i s t r y may not r e a c h a n i m a l s i n t h e s e l o c a t i o n s i m m e d i a t e l y . T h i s appears not t o be the case a t M a y f l y Creek, f o r a c i d i c w a t e r s were d e t e c t e d 0.5 m below the s u r f a c e w i t h i n 15 min a f t e r d o s i n g began. I t seems more l i k e l y t h a t r e s p o n d i n g a n i m a l s t r a v e l s l o w l y t h r o u g h the s u b s t r a t u m and r e q u i r e some time t o r e a c h the water column p r i o r t o d r i f t i n g away. A t h i r d p o s s i b i l i t y i s t h a t f o r a n i m a l s r e s i d i n g w i t h i n l e a f - p a c k s , the l a r g e s u r r o u n d i n g s u r f a c e a r e a of o r g a n i c matter may adsorb some c a t i o n s , such as aluminum, t h e r e b y p r o v i d i n g some " b u f f e r i n g " . 71 In e x p e r i m e n t s 1 and 3, T r i c h o p t e r a e x h i b i t e d a d e l a y e d response t o aluminum which may have been r e l a t e d t o the f a c t t h a t many of the s e a n i m a l s l i v e i n l e a f - p a c k s and do not have immediate a c c e s s t o the water column. In s p i t e of t h i s , i t i s l i k e l y t h a t p h y s i o l o g i c a l f a c t o r s may a l s o be r e s p o n s i b l e f o r the o b s e r v e d d e l a y e d r e s p o n s e , s i n c e T r i c h o p t e r a were a b l e t o respond i m m e d i a t e l y when a c i d was added i n experiment 2. A l t h o u g h t h e r e i s abundant e v i d e n c e a v a i l a b l e from many s i t e s i n Europe (Jones 1948; Zieman 1975; Ston e r e t a l . 1984) and S c a n d i n a v i a ( O t t o and Svensson 1983) i n d i c a t i n g reduced c a d d i s f l y d i v e r s i t y i n a c i d i c w a t e r s , t h e r e a re a l s o r e p o r t s t h a t some T r i c h o p t e r a , p a r t i c u l a r l y s h r e d d e r s , can be abundant i n a c i d i c streams ( F r i b e r g e t a l . 1980; Mackay and Kersey 1985). D u r i n g e x p e r i m e n t a l a c i d i f i c a t i o n ( H 2 S O a ) , H a l l e t a l . (1982) found t h a t the d i v e r s i t y of c a d d i s f l i e s d r i f t i n g i n t o the a c i d i f i e d stream s e c t i o n was h i g h e r than f o r d e p a r t i n g c a d d i s f l i e s , s u g g e s t i n g t h a t a t l e a s t some T r i c h o p t e r a , t o l e r a n t of pH 4 w a t e r s , were r e m a i n i n g i n the e x p e r i m e n t a l stream s e c t i o n . By c o n t r a s t , my r e s u l t s from e x p e r i m e n t s 1 and 3 suggest t h a t many M a y f l y Creek T r i c h o p t e r a a r e p h y s i o l o g i c a l l y s e n s i t i v e t o d i s s o l v e d A l 3 + i o n s . The immediate response by T r i c h o p t e r a t o a c i d a d d i t i o n s i n experiment 2 may not be i n c o n f l i c t w i t h r e s u l t s from aluminum e x p e r i m e n t s because t h e r e i s a minimum of 12 T r i c h o p t e r a s p e c i e s p r e s e n t a t t h i s s i t e (see A.1.2.1). C o n s e q u e n t l y , t h i s r esponse t o a c i d may have been by an e n t i r e l y d i f f e r e n t c a d d i s f l y group. Thus, my f i e l d e x p e r i m e n t s suggest t h a t w h i l e some T r i c h o p t e r a may d e t e c t and 72 respond d i r e c t l y t o moderately e l e v a t e d H + i o n l e v e l s , many more appear t o be t o l e r a n t of t h i s l e v e l but s u s c e p t i b l e t o i n c r e a s e d A l 3 + i o n c o n c e n t r a t i o n s . A l t h o u g h H y d r a c a r i n a d r i f t i n streams has p r e v i o u s l y been r e c o g n i z e d (Hynes 1970), I c o u l d f i n d no r e p o r t s i n the l i t e r a t u r e documenting t h e i r s e n s i t i v i t y t o changes i n water c h e m i s t r y . Pennak (1953), however, does mention t h a t a c i d l a k e s u s u a l l y c o n t a i n few water m i t e s . In both my e x p e r i m e n t s i n v o l v i n g aluminum (1 and 3 ) , I found a d e l a y e d response (^6 h) by members of t h i s group. In experiment 3, these a n i m a l s t o l e r a t e d pH 5.9 f o r 2 days, y e t responded q u i c k l y t o the added aluminum. T h i s suggests H y d r a c a r i n a a re much more s e n s i t i v e t o d i s s o l v e d A l 3 + than H*, a t l e a s t a t e l e v a t e d H + c o n c e n t r a t i o n s . Simulium and perhaps P l e c o p t e r a were a p p a r e n t l y s e n s i t i z e d by exposure t o 48 h H C l , because they s h i f t e d from no response t o aluminum i n experiment 1, t o a d e l a y e d response i n experiment 3. D u r i n g p r o l o n g e d exposure t o a c i d and aluminum, a n i m a l s may e x p e r i e n c e d i s r u p t i o n of p h y s i o l o g i c a l p r o c e s s e s , l e a d i n g t o a d e l a y e d r e s p o n s e . Immediate response D e s p i t e the s u g g e s t i o n t h a t l o t i c c h i r o n o m i d s a r e a c i d t o l e r a n t ( S u t c l i f f e and C a r r i c k 1973), t h e r e i s e v i d e n c e from f i e l d s u r v e y s i n a c i d streams i n d i c a t i n g t h a t some c h i r o n o m i d s a r e a c i d i n t o l e r a n t (Jones 1948; H a l l et a l . 1980, 1982; Simpson 1983; Mackay and Ker s e y 1985). For example, i n experiment 2, I found t h a t c h i r o n o m i d s of a l l s i z e s responded 73 i m mediately t o i n c r e a s e d H + c o n c e n t r a t i o n s w i t h s m a l l i n d i v i d u a l s c o n t i n u i n g t o d e p a r t t h r o u g h o u t the exposure p e r i o d . T h i s r a p i d response t o HCl may have been a t t r i b u t a b l e t o a p a r t i c u l a r l y s e n s i t i v e s p e c i e s or group; the extended response may r e f l e c t r e l a t i v e abundance of s m a l l c h i r o n o m i d s i n the b e n t h i c community. When expose t o aluminum, i n experiment 1, t h e r e was a d e l a y e d response by both l a r g e and s m a l l i n d i v i d u a l s . T h i s c o n t r a s t e d s h a r p l y w i t h the immediate response by c h i r o n o m i d s t o aluminum a d d i t i o n s d u r i n g experiment 3. Thus, I c o n c l u d e t h a t some l a r g e and s m a l l c h i r o n o m i d s are s e n s i t i v e t o s l i g h t i n c r e a s e s i n a c i d a l o n e , w h i l e o t h e r s may be t o l e r a n t of these i n t e r m e d i a t e pH l e v e l s , but i n t o l e r a n t of e l e v a t e d A l 3 + c o n c e n t r a t i o n s a t t h e same pH. I t seems r e a s o n a b l e t o s u g g e s t t h a t the s h i f t from d e l a y e d response by c h i r o n o m i d s t o aluminum i n experiment 1 t o an immediate r e s p o n s e , i n experiment 3, was due t o s e n s i t i z a t i o n by p r i o r exposure t o a c i d . The r a p i d and r e p e a t a b l e response of Ephemeroptera t o e l e v a t e d A l 3 + c o n c e n t r a t i o n s u g g e s t s these a n i m a l s a r e somehow a b l e t o d e t e c t t h i s i o n i n t h e i r environment. M a y f l i e s a r e known t o p o s s e s s chemoreceptors ( S l i f e r 1977), but I c o u l d f i n d no i n f o r m a t i o n i n d i c a t i n g whether these i o n r e c e p t i v e c e l l s " d e t e c t " d i s s o l v e d aluminum. Presumably d e t e c t i o n of ' u n d e s i r a b l e ' water q u a l i t y would be f o l l o w e d by a b e h a v i o r a l response d e s i g n e d t o remove the i n d i v i d u a l t o a more ' s u i t a b l e ' l o c a t i o n . D r i f t b e h a v i o r i s o b v i o u s l y one easy, e n e r g e t i c a l l y i n e x p e n s i v e way t o respond t o a l t e r e d water c h e m i s t r y . 74 I t has been r e p e a t e d l y demonstrated t h a t Ephemeroptera a re p a r t i c u l a r l y s e n s i t i v e t o waters below pH 5; as w e l l , some s p e c i e s a r e absent from waters more a c i d than pH 6 ( M i n s h a l l and Kuehne 1969; B e l l 1971; S u t c l i f f e and C a r r i c k 1973; Zieman 1975; F i a n c e 1978; H a l l e t a l . 1980; O t t o and Svensson 1983; H a l l et a l . 1985; Mackay and Ker s e y 1985). My exp e r i m e n t s show t h a t some Ephemeroptera, n a i v e t o a c i d i f i c a t i o n , a r e indeed i n t o l e r a n t of pH < 6 b u t , more i m p o r t a n t l y , t h e r e appears t o be an even g r e a t e r a v o i d a n c e response t o a c i d i c waters c o n t a i n i n g e l e v a t e d d i s s o l v e d aluminum c o n c e n t r a t i o n s . _4.__.3_ Community/ecosystem i m p l i c a t i o n s The r a t e at which Ephemeroptera responded i n my ex p e r i m e n t s argues a g a i n s t the s u g g e s t i o n ( S u t c l i f f e and C a r r i c k 1973) t h a t absence of g r a z e r s from a c i d i c waters i s due t o d e c r e a s e d food q u a l i t y or a v a i l a b i l i t y . In f a c t , t h e r e i s now growing e v i d e n c e t h a t l o s s of g r a z i n g i n v e r t e b r a t e s ( e . g . , many Ephemeroptera) due t o a c i d i f i c a t i o n p roduces i n c r e a s e d abundance of f i l a m e n t o u s a l g a e (Hendrey 1976; H a l l e t a l . 1980), a p o o r e r q u a l i t y food f o r many i n v e r t e b r a t e g r a z e r s . For most l o t i c i n v e r t e b r a t e s t h e r e a re l i k e l y t o be few r e f u g e s a v a i l a b l e when stream waters a c i d i f y . S i n c e b e n t h i c r e c o l o n i z a t i o n of d i s t u r b e d h a b i t a t s appears t o be l a r g e l y from upstream p o p u l a t i o n s v i a d r i f t (Hynes 1970; Waters 1972), d e c i m a t i o n of headwater communities may a l s o a f f e c t downstream communities as w e l l . In terms of community c o m p o s i t i o n , i t i s p o s s i b l e t o see 75 a c i d i f i c a t i o n as a phenomenon f o r which t h e r e are p r e c e d e n t s i n the l o t i c community. For example, i f j u v e n i l e s t a g e s are p a r t i c u l a r l y s e n s i t i v e , then the community consequences may be s i m i l a r t o s i z e - s e l e c t i v e p r e d a t i o n upon s m a l l s t a g e s (see Newman and Waters 1984). As w e l l , downstream d i s p l a c e m e n t of i n v e r t e b r a t e s due t o a c i d i f i c a t i o n may be s i m i l a r t o the impacts of f l o o d i n g . In f a c t , d r i f t response of l o t i c i n v e r t e b r a t e s t o d i s t u r b a n c e s s u g g e s t s t h a t t h i s b e h a v i o r a l c h a r a c t e r i s t i c i s g e n e r a l l y advantageous, a t l e a s t f o r some groups (see G u r t z and W a l l a c e 1984). Absence of a g i v e n s p e c i e s from o t h e r w i s e a c c e p t a b l e a c i d i c h a b i t a t s may be the consequence of many f a c t o r s i n c l u d i n g : (1) " d e t e c t i o n " and a v o i d a n c e response; (2) p h y s i o l o g i c a l i n t o l e r a n c e t o ambient water q u a l i t y of a t l e a s t one l i f e s t a g e ; (3) i n c r e a s e d m o r t a l i t y d u r i n g m o u l t i n g or emergence; (4) f a i l u r e t o a v o i d p r e d a t i o n (perhaps due t o p h y s i o l o g i c a l s t r e s s ) ; (5) inadequate food abundance and/or q u a l i t y ; (6) p h y s i c a l a l t e r a t i o n of h a b i t a t ( e . g . , d e c r e a s e i n s u r f a c e t e n s i o n ) ; (7) b i o - a c c u m u l a t i o n of t o x i c body burden; (8) f a i l u r e t o c o l o n i z e due t o h a b i t a t a v o i d a n c e by egg-l a y i n g f e m a l e s ; (9) s y n e r g i s t i c i n t e r a c t i o n s between s t r e s s f a c t o r s . Only a few of t h e s e f a c t o r s a r e l i k e l y t o dominate i n s h o r t time frames (< 1 g e n e r a t i o n ) . R a p i d responses ( e . g . , w i t h i n 45 min) 76 a r e p r o b a b l y due t o d e t e c t i o n and a v o i d a n c e , w h i l e d e l a y e d responses (> 6 h) may be the r e s u l t of p h y s i o l o g i c a l d i s t u r b a n c e s . Longer term responses (> 24 h) may be due t o i n c r e a s e d s u s c e p t i b i l i t y t o p r e d a t i o n , changes i n food q u a l i t y , or a c o m b i n a t i o n of these and o t h e r f a c t o r s . Thus, f o l l o w i n g a c i d i f i c a t i o n , a n i m a l s f a i l i n g t o d e p a r t may s t i l l succumb i n the l o n g term due to o t h e r f a c t o r s . As an agent of s e l e c t i o n , stream a c i d i f i c a t i o n may f a v o r i n v e r t e b r a t e l i f e h i s t o r y p a t t e r n s t h a t reduce exposure of i n d i v i d u a l s t o p e r i o d s i n which a c i d i f i c a t i o n i s most p r o b a b l e . Due t o the s e a s o n a l n a t u r e of a c i d i n p u t s t o streams, the g r e a t e s t impacts of contemporary a c i d i f i c a t i o n may be on s p r i n g -emerging s p e c i e s , f o r m o u l t i n g and emergence have been shown t o be p e r i o d s i n which a n i m a l s are p a r t i c u l a r l y s e n s i t i v e t o a c i d s ( B e l l and Nebeker 1969; B e l l 1971). I n c r e a s i n g l y t h e r e i s e v i d e n c e t h a t l o n g - t e r m a c i d i f i c a t i o n not o n l y r e s u l t s i n a l t e r e d s p e c i e s c o m p o s i t i o n , but can l e a d t o the e v o l u t i o n of s p e c i e s l i m i t e d t o a c i d environments (Whitton and Say 1975). I t i s l i k e l y t h a t the most s e n s i t i v e s p e c i e s i n headwater streams i n e a s t e r n Canada, n o r t h e a s t e r n U.S.A. and S c a n d i n a v i a have a l r e a d y been e l i m i n a t e d , l e a v i n g behind a community of organisms w i t h a broader t o l e r a n c e t o changes i n water c h e m i s t r y (Hawkins et a l . 1982). L i k e e u t r o p h i c a t i o n , a c i d i f i c a t i o n i s , i n p a r t , a n a t u r a l p r o c e s s and, as such, i s " t o l e r a b l e " by b i o t a . What i s i n t o l e r a b l e t o some s p e c i e s i s the r a t e a t which changes t a k e p l a c e i n t h e i r medium. 77 4.2 P h y s i c a l - c h e m i c a l Each time I added aluminum c h l o r i d e t o M a y f l y Creek ( e x p e r i m e n t s 1 and 3) foam accumulated i n backwater a r e a s and i n the d r i f t n e t s . T h i s foam was f r o t h y , t i n t e d w i t h a s l i g h t y e l l o w c o l o r and appeared t o have minute o r g a n i c p a r t i c l e s i n c o r p o r a t e d i n the m a t r i x . A p p a r e n t l y , a d d i n g aluminum causes d i s s o l v e d o r g a n i c m o l e c u l e s t o c o a g u l a t e ; the a c c u m u l a t i n g foam i n d i c a t e d reduced s u r f a c e t e n s i o n ( H a l l e t a l . 1985a) and p r o b a b l y c o n t a i n e d e l e v a t e d m e t a l c o n c e n t r a t i o n s ( E i s e n r e i c h e t a l . 1978). The i n c r e a s e d c o n d u c t i v i t y measured d u r i n g e x p e r i m e n t s 1 and 2 was e x p e c t e d , f o r H a l l et a l . (1980, 1985a) have shown t h a t i n c r e a s i n g .stream water a c i d i t y m o b i l i z e s exchangeable i o n s from the benthos which then c o n t r i b u t e t o e l e c t r i c a l c o n d u c t i v i t y . What was unexpected were the lower r e a d i n g s d u r i n g the A1C1 3 experiment than d u r i n g the HCl e x p e r i m e n t . My e x p e c t a t i o n was t h a t c o n d u c t i v i t y s h o u l d have been h i g h e r i n the aluminum t r i a l due t o e l e v a t e d d i s s o l v e d C I " and A l 3 + i o n l e v e l s . Perhaps foam p r o d u c t i o n e x t r a c t e d s u f f i c i e n t numbers of i o n s t o reduce e l e c t r i c a l c o n d u c t i v i t y . The i n c r e a s e d C a + , Mg +, N a + , and K + c o n c e n t r a t i o n s observed i n these e x p e r i m e n t s c o n f i r m r e s u l t s o b t a i n e d i n s i m i l a r f i e l d e x p e riments u s i n g H2SOi, and i n c r e a s i n g stream water a c i d i t y t o pH 4 ( H a l l e t a l . 1980). Based upon f i e l d ( H a l l e t a l . 1980) and l a b o r a t o r y (Norton 1981) e x p e r i m e n t s , c o n c e n t r a t i o n s of o t h e r m e t a l s , such as Zn, Mn, Fe, Cd, and Cu, a r e e x p e c t e d t o i n c r e a s e under a c i d i c c o n d i t i o n s as a r e s u l t of d e s o r p t i o n from 78 the stream s u b s t r a t u m . T h i s was not o b s e r v e d i n t h e s e f i e l d e x p e r i m e n t s , presumably because a c i d i t y was o n l y s l i g h t l y e l e v a t e d . The i n c r e a s e d i o n c o n c e n t r a t i o n s r e c o r d e d i n t h e s e e x p e r i m e n t s were w e l l w i t h i n the range of normal f l u c t u a t i o n e x p e c t e d f o r streams i n t h i s a r e a (M. F e l l e r , unpub. d a t a ) . F u r t h e r m o r e , background c o n c e n t r a t i o n s of c a l c i u m (2.4 mg/L = 119.8 meq/L), magnesium (0.3 mg/L = 24.7 meq/L), and a l k a l i n i t y (105.7 Meq/L) found a t M a y f l y Creek are v e r y c l o s e t o the t h e o r e t i c a l r e l a t i o n s h i p p r e d i c t e d f o r waters u n a f f e c t e d by a c i d i c p r e c i p i t a t i o n (NRCC 1981). T h i s h e l p s c o n f i r m t h a t t h i s s i t e i s c u r r e n t l y r e l a t i v e l y u n a f f e c t e d by a c i d p r e c i p i t a t i o n , and the a q u a t i c community s h o u l d , t h e r e f o r e , be r e l a t i v e l y n a i v e t o a c i d i f i c a t i o n . Temperature p l a y s a m i n i m a l r o l e i n c o n t r o l l i n g m e t a l t o x i c i t y d i r e c t l y ; however, t h r o u g h i t s i n f l u e n c e on water c h e m i s t r y i t can i n d i r e c t l y a f f e c t t o x i c i t y . For example, a l t h o u g h p r e d o m i n a t e l y c o n t r o l l e d by pH, aluminum s o l u b i l i t y and s p e c i a t i o n can be a f f e c t e d by t e m p e r a t u r e , a l b e i t m i n i m a l l y (Burrows 1977). D e c r e a s i n g t e m p e r a t u r e r e s u l t s i n i n c r e a s e d aluminum s a t u r a t i o n ; t h i s i n t u r n can l e a d t o i n c r e a s e d t o x i c i t y (Baker and S c h o f i e l d 1982). Aluminum c o n c e n t r a t i o n s a t the temperature a t which t h e s e e x p e r i m e n t s were conducted were s u p e r s a t u r a t e d (May e t a l . 1979) as i n d i c a t e d . b y a f a i n t m i l k y c o l o r presumably due t o aluminum h y d r o x i d e s . D u r i n g t h i s s t u d y , background c h l o r i d e i o n c o n c e n t r a t i o n s measured were below the annual mean e x p e c t e d f o r headwater streams a t the U.B.C. Research F o r e s t . However, because C l " 79 c o n c e n t r a t i o n s here v a r y w i t h d i s c h a r g e and are t y p i c a l l y a t a minimum d u r i n g l a t e summer ( F e l l e r and Kimmins 1979), the low c o n c e n t r a t i o n s r e c o r d e d were normal. N e v e r t h e l e s s , d u r i n g both the HCl and A1C1 3 e x p e r i m e n t s , C I " c o n c e n t r a t i o n s were at l e a s t double maximum v a l u e s r e c o r d e d a t nearby S p r i n g Creek ( F e l l e r unpub. d a t a ) . 4._3 Methods e v a l u a t i o n Many a u t h o r s have commented on the n e c e s s i t y t o use f i n e n e t s t o c a p t u r e e a r l y i n s t a r s of many s p e c i e s . S u t e r and B i s h o p (1980) and Z e l t and C l i f f o r d (1972) recommend n e t s w i t h a mesh s i z e of 100 Mm or s m a l l e r f o r use i n l i f e c y c l e s t u d i e s i n which a l l i n d i v i d u a l s of a p o p u l a t i o n must be sampled. However, Mundie (1971) "showed t h a t even when s a m p l i n g w i t h n e t s of 120 um mesh s i z e , over 50% of the a n i m a l s p r e s e n t can s t i l l be m i s s e d . Many of the s m a l l a n i m a l s p a s s i n g t h r o u g h the 120 /nm mesh i n h i s study were c h i r o n o m i d s , but o t h e r l a r v a e were missed as w e l l , i n c l u d i n g some a q u a t i c i n s e c t s i n e a r l y i n s t a r s . As- o u t l i n e d i n S e c t . D.1.2.1, I found s i m i l a r r e s u l t s u s i n g a 296 um mesh s i e v e i n the l a b o r a t o r y . U n f o r t u n a t e l y , l a r g e q u a n t i t i e s of o r g a n i c p a r t i c l e s were c a p t u r e d by the 86 urn mesh n e t s d u r i n g f i e l d e x p e r i m e n t s . By u s i n g s m a l l (86 Mm) n e t s i n the f i e l d combined w i t h a l a r g e r mesh (296 Mm) s i e v e i n the l a b o r a t o r y , I was a b l e t o both c a p t u r e s m a l l a n i m a l s and remove most of the t i n y o r g a n i c p a r t i c l e s p r i o r t o c o u n t i n g the samples. Because h a r p a c t a c o i d copepods do not show d i e l f l u c t u a t i o n s i n d r i f t d e n s i t y a t t h i s s i t e (see S e c t . A . 2 ) , they a r e good 80 i n d i c a t o r s p e c i e s t o use i n e v a l u a t i n g methods used t o o b t a i n d a t a i n t h e s e e x p e r i m e n t s . The r e l a t i v e l y c l o s e agreement between d r i f t d e n s i t i e s r e c o r d e d at b o t h s i t e s i n d i c a t e s t h e r e were no s u b s t a n t i a l d i f f e r e n c e s i n h a n d l i n g samples from t h e two s i t e s . D e s p i t e v a r i a b i l i t y i n copepod d r i f t r a t e s , o v er t i m e , t h e r e were no s u b s t a n t i a l d i f f e r e n c e s i n c a t c h e s a t t h e two s i t e s . As w e l l , between-date comparisons of d r i f t d e n s i t y r e c o r d e d a t the c o n t r o l s i t e (1) f o r o t h e r s m a l l a n i m a l s (Ephemeroptera, c h i r o n o m i d s , P l e c o p t e r a , and H y d r a c a r i n a ) , r e v e a l s s i m i l a r r e s u l t s , r e g a r d l e s s of d a t e . T h i s s u g g e s t s t h a t the methods used t o c o l l e c t and p r o c e s s samples were c o n s i s t e n t . I t i s d i f f i c u l t t o e x t r a p o l a t e r e s u l t s from s h o r t term e x p e r i m e n t s i n August t o l o n g term community changes a s s o c i a t e d w i t h s p r i n g a c i d i f i c a t i o n , and from mountain streams on t h e west c o a s t t o l o t i c systems i n d i f f e r e n t g e o g r a p h i c r e g i o n s . However, r e s u l t s o b t a i n e d i n t h e s e e x p e r i m e n t s c o n f i r m the r e l a t i v e s e n s i t i v i t y p a t t e r n s observed i n s y n o p t i c s u r v e y s and e x p e r i m e n t s e l s e w h e r e . Thus, c a r r y i n g out t h e s e e x p e r i m e n t s i n August appears not t o have s i g n i f i c a n t l y a l t e r e d the f i n d i n g s . D e t e r m i n a t i o n of pH does not p r o v i d e a d i r e c t , q u a n t i t a t i v e measurement of s o l u t i o n a c i d i t y ; i t i s , however, g e n e r a l l y c o n s i d e r e d a r e l i a b l e i n d i c a t o r of a c i d c o n c e n t r a t i o n (ASTM 1981), but c e r t a i n p r e c a u t i o n s must be ob s e r v e d i n pH measurement. For example, i n r u n n i n g waters of low c o n d u c t i v i t y (<5 nS/cm), s t r e a m i n g p o t e n t i a l s can d e v e l o p (ASTM 1981). I was a b l e t o overcome t h i s tendency by u s i n g a grounded 1, s t a i n l e s s -s t e e l f l o w chamber. 81 CHAPTER 5. CONCLUSIONS AND RECOMMENDATIONS 5_.J_ C o n c l u s i o n s With few e x c e p t i o n s , i n v e r t e b r a t e s l i v i n g i n streams i n the Coast Range Mountains of B r i t i s h Columbia have no p r e v i o u s h i s t o r y of exposure t o s t r o n g a c i d s , such as t h o s e a s s o c i a t e d w i t h a c i d i c p r e c i p i t a t i o n . These streams a r e not o n l y g e o c h e m i c a l l y s u s c e p t i b l e t o a c i d i f i c a t i o n , but t h e i r b i o t a are s e n s i t i v e t o i n c r e a s e d H + and A l 3 + c o n c e n t r a t i o n s , as shown i n the e c o t o x i c o l o g i c a l s t u d i e s r e p o r t e d i n t h i s t h e s i s . Ephemeroptera, p a r t i c u l a r l y e a r l y i n s t a r s of some s p e c i e s , seem c a p a b l e of r a p i d l y (<1 h) d e t e c t i n g low c o n c e n t r a t i o n s of d i s s o l v e d aluminum (^ 1 mg/L). S i m i l a r l y , Chironomidae and T r i c h o p t e r a d e t e c t e l e v a t e d hydrogen i o n c o n c e n t r a t i o n s (pH 5.9). As one apparent a v o i d a n c e r e s p o n s e , a f f e c t e d i n d i v i d u a l s e n t e r the water column and d r i f t downstream. E a r l y d e v e l o p m e n t a l s t a g e s of Ephemeroptera and Chironomidae may be l e s s t o l e r a n t of i n c r e a s e d A l 3 + and H + c o n c e n t r a t i o n s than are l a t e r i n s t a r s . T r i c h o p t e r a , H y d r a c a r i n a and c h i r o n o m i d s , w i t h minimal (< 12 h) p r i o r exposure t o s t r o n g a c i d s , e x h i b i t d e l a y e d (6 h) response t o i n c r e a s e d d i s s o l v e d aluminum i o n c o n c e n t r a t i o n s . P r e - e x p o s u r e t o a c i d r e s u l t s i n enhanced s e n s i t i v i t y t o d i s s o l v e d aluminum f o r Simulium, P l e c o p t e r a and Chironomidae. The o b s e r v e d 6 h d e l a y and s e n s i t i z a t i o n by p r o l o n g e d a c i d exposure suggest a p h y s i o l o g i c a l mechanism u n d e r l y i n g observed e x p e r i m e n t a l r e s u l t s , r a t h e r than mere a v o i d a n c e . 82 E x p e r i m e n t a l l y i n c r e a s e d d i s s o l v e d aluminum i o n c o n c e n t r a t i o n not o n l y i n t e n s i f i e s b i o l o g i c a l response t o a c i d i f i c a t i o n , but a l s o c o n t r i b u t e s t o stream water a c i d i t y . On the o t h e r hand, a r t i f i c i a l e l e v a t i o n (< 5 mg/L) c f C I " c o n c e n t r a t i o n s i n these e x p e r i m e n t s t h r o u g h _i_n s i t u A1C1 3 and HCl a d d i t i o n s does not s t i m u l a t e d r i f t response by Chironomidae l a r v a e and Ephemeroptera nymphs. E c o t o x i c o l o g i c a l methods, such as t h o s e d e v e l o p e d f o r t h i s s t u d y , p e r m i t the i n v e s t i g a t o r t o s i m u l t a n e o u s l y expose a wide v a r i e t y of organisms and l i f e s t a g e s t o p r e s c r i b e d p e r t u r b a t i o n s under r e a l i s t i c t e s t c o n d i t i o n s . R e s u l t s from such s t u d i e s would be e x t r e m e l y hard t o d u p l i c a t e u s i n g t r a d i t i o n a l b i o a s s a y t e c h n i q u e s . F u r t h e r m o r e , s i n g l e s p e c i e s t e s t s f a i l t o even i n v e s t i g a t e i m p o r t a n t s p e c i e s i n t e r a c t i o n s t h a t may change under the i n f l u e n c e of the t o x i c a g e n t . On the o t h e r hand, i t i s d i f f i c u l t t o c o n t r o l f o r a l l the v a r i a b l e s t h a t can i n f l u e n c e r e s u l t s of f i e l d e x p e r i m e n t s , making i t more d i f f i c u l t t o i n t e r p r e t d a t a o b t a i n e d , t h i s way. F u r t h e r m o r e , as H u r l b u r t (1984) p o i n t e d o u t , i t can be e x t r e m e l y d i f f i c u l t t o r e p l i c a t e such f i e l d e x p e r i m e n t s i n a s t a t i s t i c a l l y sound manner. N e v e r t h e l e s s , e c o t o x i c o l o g i c a l s t u d i e s can be i n v a l u a b l e f o r t e s t i n g h y p o t h e s e s r e g a r d i n g how a g i v e n ecosystem w i l l respond t o a s p e c i f i e d p e r t u r b a t i o n . E q u a l l y i m p o r t a n t , they can p r o v i d e f u r t h e r hypotheses t h a t can be i n v e s t i g a t e d i n g r e a t e r d e t a i l i n l a b o r a t o r y s t u d i e s under c o n t r o l l e d c o n d i t i o n s . 83 5.2 S i g n i f i c a n c e To d a t e , much of our knowledge r e g a r d i n g the r e l a t i o n s h i p between d i s t r i b u t i o n of l o t i c i n v e r t e b r a t e s and c h e m i c a l f a c t o r s has been a c q u i r e d through f i e l d s u r v e y s . W h i l e t h e s e methods have been u s e f u l i n h e l p i n g e s t a b l i s h t h a t such a r e l a t i o n s h i p e x i s t s , they are but a f i r s t s t e p toward an u n d e r s t a n d i n g of the u n d e r l y i n g mechanisms. Because of i n h e r e n t weaknesses, s y n o p t i c s u r v e y s are a l s o p o o r l y s u i t e d t o d e t e c t i n g e f f e c t s r e s u l t i n g from i n t r o d u c t i o n of i n s i d i o u s c h e m i c a l s , such as a c i d s , i n t o the environment. These weaknesses i n c l u d e the f o l l o w i n g : (1) e p i s o d i c e v e nts may be e n t i r e l y m i s s e d ; (2) s u b t l e changes i n c r i t i c a l b i o l o g i c a l parameters ( e . g . , f e c u n d i t y , r e c r u i t m e n t , and- growth) may escape d e t e c t i o n ; (3) r a r e l y a r e s u f f i c i e n t samples taken t o e s t a b l i s h s e a s o n a l or h i s t o r i c a l t r e n d s ; (4) r e l a t i v e f u n c t i o n a l " i m p o r t a n c e " of each sampled s p e c i e s t o the community i s unknown; e.g. " k e y s t o n e " s p e c i e s ( P a i n e 1980) may not be i d e n t i f i e d as such; (5) " r a r e " p o p u l a t i o n s w i l l p r o b a b l y be m i s s e d , or a t l e a s t under-sampled; (6) remote, i n a c c e s s i b l e , or seemingly unimportant h a b i t a t s , such as headwater streams, may r e c e i v e i n s u f f i c i e n t s a m p l i n g e f f o r t . C o n s e q u e n t l y , o n l y the more o b v i o u s , l o n g - t e r m changes i n community c o m p o s i t i o n can be d e t e c t e d u s i n g survey methods. More s o p h i s t i c a t e d t e c h n i q u e s are r e q u i r e d t o d e t e c t e a r l y 84 warning " s i g n a l s " t h a t r e s u l t from e n v i r o n m e n t a l p e r t u r b a t i o n s . Based upon f i e l d o b s e r v a t i o n s , hypotheses r e g a r d i n g the r o l e of s p e c i f i c c h e m i c a l f a c t o r s i n the s t r u c t u r e and f u n c t i o of i n v e r t e b r a t e communities can be f o r m u l a t e d and s u b s e q u e n t l y t e s t e d t h r o u g h v a r i o u s t y p e s of e x p e r i m e n t a t i o n . The c u r r e n t importance of a c i d p r e c i p i t a t i o n i s s u e s has r e - f o c u s e d a t t e n t i o n on the i n f l u e n c e t h a t c h e m i c a l f a c t o r s can have on a q u a t i c communities. Through e a r l y f i e l d s t u d i e s by J e w e l l (1922), Jones (1948, 1949a,b), H a l l (1951 ), and many o t h e r s , a w e a l t h of i n f o r m a t i o n l i n k i n g s p e c i f i c c h e m i c a l c o n d i t i o n s t o the presence or absence of p a r t i c u l a r s p e c i e s has been g a t h e r e d . These h i s t o r i c a l r e c o r d s r e l a t i n g stream pH and a n i m a l d i s t r i b u t i o n must be approached w i t h c a u t i o n , though, f o r a v a r i e t y of reasons i n c l u d i n g : (1) Many of the e a r l y methods used t o determine pH i n the f i e l d a r e i n a c c u r a t e by today's s t a n d a r d s (Haines e t a l . 1983). (2) These r e p o r t s r a r e l y p r o v i d e s u f f i c i e n t i n f o r m a t i o n t o determine whether t h e h a b i t a t b e i n g i n v e s t i g a t e d was a c i d i c due t o o r g a n i c a c i d s ( e . g . , d y s t r o p h i c w a t e r s ) or t o much s t r o n g e r m i n e r a l a c i d s . (3) S i n c e s t r e a m water a c i d i t y v a r i e s w i t h d i s c h a r g e ( L i k e n s e t a l . 1977), and few s t u d i e s have been comprehensive enough t o e s t a b l i s h the a c i d i t y range t o which a g i v e n community might be exposed over t i m e , i t i s d i f f i c u l t t o i n t e r p r e t p r e v i o u s l y r e p o r t e d b i o t a / w a t e r 85 a c i d i t y r e l a t i o n s h i p s . (4) S i n c e the metal c o n t e n t i n many a c i d i c w aters can be e l e v a t e d , i t i s i m p o s s i b l e , w i t h o u t thorough c h e m i c a l a n a l y s e s , t o s e p a r a t e e f f e c t s due t o metal i o n s from t h o s e d i r e c t l y a t t r i b u t a b l e t o hydrogen i o n s . The work r e p o r t e d i n t h i s t h e s i s o f f e r s two main c o n t r i b u t i o n s . F i r s t , my e x p e r i m e n t a l r e s u l t s f u r t h e r u n d e r s t a n d i n g of the r o l e p l a y e d by d i s s o l v e d aluminum i n s t r u c t u r i n g f r e s h w a t e r communities a f f e c t e d by a c i d i c p r e c i p i t a t i o n . Second, my r e s e a r c h demonstrates the v a l u e of e x p e r i m e n t a l l y t e s t i n g hypotheses u s i n g e c o t o x i c o l o g i c a l methods. Both t r a d i t i o n a l l a b o r a t o r y b i o a s s a y s and e c o t o x i c o l o g i c a l f i e l d e x p e r i m e n t s can c o n t r i b u t e t o u n d e r s t a n d i n g and p r e d i c t i o n of e c o l o g i c a l i m p a c t s . However, we must always be aware of the l i m i t a t i o n s a s s o c i a t e d w i t h each method and e x p e r i m e n t . For example, r e s u l t s of in. s i t u e x p e r i m e n t s t e s t i n g i n v e r t e b r a t e responses t o a l t e r e d H + and A l 3 + l e v e l s i n n o r t h e a s t e r n streams w i l l be l i m i t e d t o p r e d i c t i n g how a l r e a d y impacted systems w i l l respond t o f u r t h e r a c i d i f i c a t i o n . U n f o r t u n a t e l y , i t i s i m p o s s i b l e t o i n v e s t i g a t e h i s t o r i c a l e v e n t s i n these streams o c c u r r i n g i n e a r l y s t a g e s of a c i d i f i c a t i o n . A l t e r n a t i v e l y , by e x p e r i m e n t a l l y a c i d i f y i n g ecosystems o u t s i d e a r e a s c u r r e n t l y a f f e c t e d by a c i d d e p o s i t i o n , "warning s i g n a l s " can be i d e n t i f i e d and a p p l i e d t o a r e a s near t h o s e c u r r e n t l y a f f e c t e d . Because of the l o c a t i o n where my e x p e r i m e n t s took p l a c e , t h i s r e s e a r c h r e p r e s e n t s j u s t such a 86 s t u d y . From these r e s u l t s , we see why s u r v e y s u s i n g s a m p l i n g d e v i c e s w i t h c o a r s e mesh and i n f r e q u e n t s a m p l i n g p e r i o d s have f a i l e d t o d e t e c t e a r l y "warning s i g n a l s " of m i l d a c i d i f i c a t i o n . Documenting the e x t e n t and " s e v e r i t y " of e c o l o g i c a l e f f e c t s r e s u l t i n g from a c i d i f i c a t i o n i s a c o n t r i b u t i o n not o n l y toward an u n d e r s t a n d i n g of the e f f e c t s themselves and what causes them, but a l s o t o the p r o c e s s of d e a l i n g w i t h t h i s complex i s s u e . 5.3 Recommendations f o r F u t u r e R e s e a r c h C o n c e r n i n g the e f f e c t of a c i d i f i c a t i o n on stream i n v e r t e b r a t e s , many unanswered q u e s t i o n s remain. F u n d a m e n t a l l y , I see the need f o r two, complementary l i n e s of i n v e s t i g a t i o n : (1) e c o l o g i c a l and (2) p h y s i o l o g i c a l . E c o l o g i c a l s t u d i e s c o u l d be u s e f u l i n answering the f o l l o w i n g q u e s t i o n s . (1) What i s the f a t e of a n i m a l s d r i f t i n g downstream i n response t o c h e m i c a l p e r t u r b a t i o n s ? (2) I f d i s p l a c e d a n i m a l s c o l o n i z e - the benthos f u r t h e r downstream, what e f f e c t does t h i s have on the b e n t h i c community at t h a t l o c a t i o n ? (3) I f p r e c i p i t a t i o n a c i d i t y i s c o n t r o l l e d , what f a c t o r s might i n f l u e n c e the " r e s t o r a t i o n " of i n v e r t e b r a t e communities i n headwater streams "damaged" by a c i d and aluminum exposure? P h y s i o l o g i c a l s t u d i e s might attempt t o p r o v i d e answers t o these q u e s t i o n s . (1) Are t h e r e sharp n o n - l i n e a r i t i e s i n the dose-response 87 r e l a t i o n s h i p f o r " s e n s i t i v e " i n v e r t e b r a t e s exposed t o d i s s o l v e d aluminum? (2) What p h y s i o l o g i c a l mechanisms are i n v o l v e d i n r a p i d r esponses t o changes i n water c h e m i s t r y , such as avoidance b e h a v i o r ; a re d i f f e r e n t p r o c e s s e s r e s p o n s i b l e f o r d e l a y e d responses? (3) Are some forms of aluminum more t o x i c t o f r e s h w a t e r i n v e r t e b r a t e s than a r e o t h e r s ? (4) Why are e a r l y i n s t a r s more s e n s i t i v e t o e l e v a t e d H + and A l 3 + c o n c e n t r a t i o n s than a r e more f u l l y developed a n i m a l s ? 88 REFERENCES CITED ASTM. 1981. S t a n d a r d t e s t methods f o r pH of w a t e r . Amer. Soc. T e s t i n g M a t e r i a l s , P h i l a d e l p h i a . Method D 1293-78. A l l a n , J.D.,' and E. Russek. 1985. The q u a n t i f i c a t i o n of stream d r i f t . Can. J . F i s h . Aquat. S c i . 42:210-215. APHA. 1984. S t a n d a r d methods f o r the e x a m i n a t i o n of water and wastewater. 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The h y p o r h e i c zone as a h a b i t a t f o r a q u a t i c i n s e c t s and a s s o c i a t e d a r t h r o p o d s . In: V.H. Resh and D.M. Rosenberg (eds.) The e c o l o g y of a q u a t i c i n s e c t s . P r a e g e r , New York. pp.430-455. 99 W i l s o n , M.S., and H.C. Yeatman. 1959. H a r p a c t i c o i d a . I n : W.T. Edmonson (ed.) Fr e s h w a t e r b i o l o g y , 2nd e d i t i o n . W i l e y , New York. pp.815-861. W o l f f , E.W., and D.A. P e e l . 1985. The r e c o r d of g l o b a l p o l l u t i o n i n p o l a r snow and i c e . Nature 313:535-540. Z e l t , K.A. and H.F. C l i f f o r d . 1972. Assessment of two mesh s i z e s f o r i n t e r p r e t i n g l i f e c y c l e s , s t a n d i n g c r o p , and pe r c e n t a g e c o m p o s i t i o n of stream i n s e c t s . Freshwat. B i o l . 2:259-269. Ziemann, H. 1975. On the i n f l u e n c e of the hy d r o g e n - i o n c o n c e n t r a t i o n and the b i c a r b o n a t e c o n c e n t r a t i o n on the s t r u c t u r e of b i o c o e n o s e s of mountain b r o o k s . I n t . Rev. ges. H y d r o b i o l . Hydrogr. 60:523-555. 100 APPENDIX A. STUDY SITE: DETAILED DESCRIPTION OUTLINE A.1 M a y f l y Creek d e s c r i p t i o n A.1.1 A b i o t i c h a b i t a t A.1.2 R e s i d e n t b i o t a A.1.2.1 P r e l i m i n a r y l i s t of r e s i d e n t a q u a t i c i n v e r t e b r a t e s A.2 I n v e r t e b r a t e d i e l d r i f t p a t t e r n s : F i e l d s tudy A.2.1 Methods A.2.2 R e s u l t s A.3 Watershed d e s c r i p t i o n A. 3.1 Geomorphology A.3.2 Geology A.3.3 S o i l s A.3.4 C l i m a t e A.3.5 V e g e t a t i o n A.3.6 D i s t u r b a n c e H i s t o r y A.4 Atmospheric i n p u t s A.4.1 D e p o s i t i o n m o n i t o r i n g A.4.2 P r e c i p i t a t i o n c h e m i s t r y A.4.3 L o a d i n g v s . c o n c e n t r a t i o n A.4.4 C u r r e n t impacts A._1_ M a y f l y Creek d e s c r i p t i o n A.J_._1_ A b i o t i c h a b i t a t M a y f l y Creek i s a second-order stream d r a i n i n g the western s l o p e s of Golden E a r s P r o v i n c i a l P a r k , l o c a t e d a t the s o u t h e r n end of the Coast Range Mountains 50 km e a s t of Vancouver, B r i t i s h Columbia ( F i g . 2.1). The headwaters a r i s e a t about 765 m A.S.L. and f a l l t o a p p r o x i m a t e l y 315 m A.S.L. a t the j u n c t i o n of M a y f l y and Jacobs Creeks (49° 19' N, 122° 33' W). F i e l d e x p e r i m e n t s were conducted on the f l o o r of t h i s montane v a l l e y on M a y f l y Creek, j u s t upstream of the j u n c t i o n w i t h Jacobs Creek ( F i g . 2.2). A l t h o u g h the upper watershed i s s t e e p (30°-35° g r a d i e n t ) , the g r a d i e n t a t the s t u d y s i t e i s l e s s than 5°. A d e t a i l e d d e s c r i p t i o n of the watershed, i n c l u d i n g i n f o r m a t i o n on g e o l o g y , i s found i n S e c t i o n A.3; a t m o s p h e r i c i n p u t s ( c h e m i s t r y ) are d i s c u s s e d i n S e c t i o n A.4. In M a y f l y Creek the stream s u b s t r a t u m i s composed l a r g e l y of igneous r o c k s r a n g i n g i n s i z e from c o b b l e s t o s m a l l b o u l d e r s ; t h e s e a r e a r r a n g e d i n t y p i c a l r i f f l e - p o o l c o n f i g u r a t i o n . D u r i n g the summer t h e r e i s c o n s i d e r a b l e i n t e r s t i t i a l o r g a n i c m a t t e r p r e s e n t , but few i n t a c t l e a f packs are found. E x c a v a t i o n of the b e n t h i c s u b s t r a t e showed t h e r e t o be a t l e a s t one meter or more of a l l u v i a l d e p o s i t s above the bedrock. 101 Due t o o r o g r a p h i c p r e c i p i t a t i o n , s t e e p h i l l s i d e s , and t h i n s o i l s c o n t a i n i n g macrochannels ( F e l l e r and Kimmins 1979), r u n o f f i n t h i s a r ea i s r a p i d . Stream d i s c h a r g e a t nearby E a s t Creek i s s e a s o n a l l y v a r i a b l e and t y p i c a l l y h i g h (> 1000 L/sec) from October or November u n t i l A p r i l , f o l l o w e d by a d e c l i n e u n t i l May when a summer low (< 10 L/sec) i s e s t a b l i s h e d t h a t p e r s i s t s u n t i l the f o l l o w i n g autumn ( F e l l e r , 1975). Summer d i s c h a r g e i n M a y f l y Creek responds r a p i d l y t o i n d i v i d u a l p r e c i p i t a t i o n e v e n t s . At the study s i t e mean w i d t h i n the summer i s < 4 m, and water depth < 50 cm. There a r e no r o o t e d a q u a t i c p l a n t s p r e s e n t , the water i s u n c o l o r e d t o the naked eye and t u r b i d i t y i s low d u r i n g base f l o w c o n d i t i o n s . Stream water temp e r a t u r e s i n M a y f l y Creek v a r y from a summer h i g h up t o 20 °C t o below z e r o i n w i n t e r . However, t u r b u l e n c e and l a c k of p r o l o n g e d p e r i o d s of sub-zero temperatures n o r m a l l y p r e v e n t the lower reaches from i c i n g o v e r . In the summer, dense bank s i d e v e g e t a t i o n shades the stream t h e r e b y m o d u l a t i n g r i s e s i n t e m p e r a t u r e . A.J_.2_ R e s i d e n t b i o t a The f o l l o w i n g l i s t of a q u a t i c i n v e r t e b r a t e s p e c i e s , i d e n t i f i e d from M a y f l y Creek, was s u p p l i e d by John R i c h a r d s o n , I n s t i t u t e of Animal Resource E c o l o g y , U.B.C. P f e l i m i n a r y l i s t of r e s i d e n t a q u a t i c i n v e r t e b r a t e s  Taxon F u n c t i o n a l Group (a) Ephemeroptera Heptagen i i d a e R i t h r o g e n a Epeorus Cinyqmula Ironodes L e p t o p h l e b i a P a r a l e p t o p h l e b i a B a e t i d a e B a e t i s sp.1 B a e t i s sp.2 S i p h o n u r i d a e Ameletus E p h e m e r e l l i d a e S e r r a t e l l a sp. P r u n e l l a s p i n i f e r a P l e c o p t e r a P e r l o d i d a e Kogotus ? P t e r o n a r c i d a e P t e r o n a r c y s P e r l i d a e H e s p e r o p e r l a p a c i f i c a p r e d a t o r s ? C a l i n e u r i a c a l i f o r n i c a p r e d a t o r s s c r a p e r s , c o l l e c t o r - g a t h e r e r s s c r a p e r s , c o l l e c t o r - g a t h e r e r s c o l l e c t o r - g a t h e r e r s s c r a p e r s , c o l l e c t o r - g a t h e r e r s s c r a p e r s , c o l l e c t o r - g a t h e r e r s c o l l e c t o r - g a t h e r e r s p r e d a t o r s s h r e d d e r s r ? L e u c t r i d a e ( u n i d e n t i f i e d ) Nemour idae Podmosta Zapada c i n c t i p e s  Zapada o r e g o n e n s i s  Malenka sp. V i s o k a sp. Nemoura sp. C h l o r o p e r l i d a e S w e l t s a e x q u i s i t a  A l l o p e r l a sp. T r i c h o p t e r a Lepidostomat idae Lepidostoma sp.1 Lepidostoma sp.2 Lepidostoma sp.3 L i m n e p h i l i d a e E c c l i s o c o s m o e c u s sp Onocosmoecus u n i c o l o r sp E c c l i s o m y i a sp P h i l o p o t a m i d a e Wormaldia ? Hydropsychidae Parapsyche almota Parapsyche e l s i s P o l y c e n t r o p o d i d a e P o l y c e n t r o p u s R h y a c o p h i l i d a e R h y a c o p h i l a B r a c h y c e n t r i d a e Mic rasema s h r e d d e r s ? s h r e d d e r s c o l l e c t o r - g a t h e r e r s ? s h r e d d e r s s h r e d d e r s s h r e d d e r s c o l l e c t o r s ( f i l t e r e r s ) p r e d a t o r s p r e d a t o r s C o l e o p t e r a Elmidae Z a i t z e v i a p a r v u l a D i p t e r a S i m u l i d a e Simulium v i t t a t u m Empididae Oregeton ? T i p u l i d a e Hexatoma ? D i c r a n o t i a ? D i x i d a e ( u n i d e n t i f i e d ) Chironomidae R h e o t a n y t a r s u s Ceratopogonidae ( u n i d e n t i f i e d ) 1 03 Eucopepoda • H a r p a c t a c o i d a H y d r a c a r i n a V a r i o u s o t h e r groups i n c l u d i n g : nematods, o l i g o c h a e t e s , T u r b e l l a r i a , o s t r a c o d s , r o t i f e r s , and C o l l e m b o l a (a) Based on M e r r i t t and Cummins (1978) a t the g e n e r i c l e v e l . A.2_ I n v e r t e b r a t e d i e l d r i f t p a t t e r n s : F i e l d study A.2.__ Methods To d e s c r i b e background d r i f t p a t t e r n s , a complete s e t of h o u r l y samples were taken w i t h 86 Mm mesh n e t s from 1330 h r . on 17 June, 1982 u n t i l the same time the f o l l o w i n g day. D r i f t samples were p r e s e r v e d i n 10% f o r m a l i n u n t i l c o u n t e d . In the l a b o r a t o r y a n i m a l s from every o t h e r sample were s e p a r a t e d from o r g a n i c d e b r i s by f i l t e r i n g the samples t h r o u g h a 296 Mm mesh. R e t a i n e d a n i m a l s were then examined under a d i s s e c t i n g m i c r o s c o p e at 25X, i d e n t i f i e d , c o u n t e d , removed, and p r e s e r v e d . A.2-.2 R e s u l t s On averag e , n u m e r i c a l l y the most abundant group was the s m a l l (< 2 mm) c h i r o n o m i d s ( T a b l e A.1), f o l l o w e d by s m a l l p l e c o p t e r a n s , l a r g e c h i r o n o m i d s , h y d r a c a r i n i d s , s m a l l ephemeropterans, h a r p a c t a c o i d copepods, t r i c h o p t e r a n s , l a r g e ephemeropterans, Simulium, and l a r g e p l e c o p t e r a n s . Not a l l of the s e groups, however, d r i f t e d c o n s t a n t l y . In f a c t , d r i f t of l a r g e P l e c o p t e r a , l a r g e Ephemeroptera, and Simulium was almost e n t i r e l y l i m i t e d t o n o c t u r n a l hours whereas l a r g e c h i r o n o m i d s , i n a d d i t i o n t o showing a n o c t u r n a l peak n e a r l y double the mean d a i l y d r i f t d e n s i t y , a l s o d r i f t e d i n s u b s t a n t i a l numbers (> 50 a n i m a l s / 1 0 " L) d u r i n g d a y l i g h t h o u r s . In a d d i t i o n , h y d r a c a r i n i d s d r i f t e d d u r i n g the day, but e x h i b i t e d peak d r i f t d e n s i t i e s s h o r t l y a f t e r sunset ( F i g . A . 1 ) . The number of d r i f t i n g t r i c h o p t e r a n s e x h i b i t e d the c l a s s i c bigeminans p a t t e r n (Waters 1972), w i t h two peak d r i f t p e r i o d s d a i l y , one each around s u n r i s e and sunset ( F i g . A . 1 ) . In c o n t r a s t t o t h e s e o t h e r g r o u p s , s m a l l (< 2 mm), e a r l i e r i n s t a r s of c h i r o n o m i d s , P l e c o p t e r a , and Ephemeroptera a l l appeared t o d r i f t n e a r l y c o n s t a n t l y t h r o u g h o u t the day, as d i d the h a r p a c t a c o i d copepods ( F i g . A . 1 ) . 104 M A Y F L Y C R E E K F i n e N e t s c E i » * o a o s o o i s o e « s o t i s o T I M E ( H r s . ) 1 7 J u n e 1 9 8 2 1 8 J u n e 1 0 8 2 F i g u r e A.1 D i e l d r i f t p a t t e r n s a t M a y f l y Creek 1 0 5 A.3 Watershed d e s c r i p t i o n A . 3_.J_ Geomorphology The g r a n i t i c Coast Mountains a r i s e s h a r p l y from the n o r t h e r n margin of the F r a s e r V a l l e y and, i n the southwest p o r t i o n of t h i s range, f e a t u r e n o r t h - s o u t h o r i e n t e d v a l l e y s . M a y f l y Creek i s a t r i b u t a r y t o Jacobs Creek which d r a i n s the h i g h l a n d s between two such v a l l e y s , P i t t Lake t o the west, and A l o u e t t e Lake t o the e a s t . Jacobs Creek empties i n t o the n o r t h branch of the A l o u e t t e R i v e r , which f l o w s i n t o P i t t R i v e r and u l t i m a t e l y t he lower F r a s e r R i v e r . A . 3 . 2 Geology A c c o r d i n g t o Roddick ( 1 9 6 5 ) , the u n d e r l y i n g g e o l o g i c a l s t r u c t u r e i n t h i s a r e a i s composed m a i n l y of c o a r s e l y g r a i n e d a c i d igneous r o c k s such as q u a r t z d i o r i t e , w i t h l o c a l i z e d p o c k e t s of v o l c a n i c and sedi m e n t a r y r o c k s . There has been r e l a t i v e l y l i t t l e c h e m i c a l w e a t h e r i n g of the r o c k s p a r t l y because t h e r e a r e numerous rock f a u l t s t h r o u g h which groundwater can t r a v e l . T h i s area was g l a c i a t e d a t l e a s t 3 - 4 t i m e s d u r i n g the P l e i s t o c e n e (Armstrong, 1 9 5 6 ) , so the u n d e r l y i n g t i l l s have been f r e q u e n t l y reworked. A . 3 _ . 3 S o i I s In the watershed s o i l t h i c k n e s s v a r i e s w i t h l o c a t i o n and l a n d forms, and ranges from v i r t u a l l y absent near the headwaters t o over 1 m on the v a l l e y f l o o r . G e n e r a l l y the p o d z o l i c s o i l s d o m i n a t i n g t h i s area a r e r i c h i n o r g a n i c m a t t e r , have a c o a r s e t e x t u r e ( F e l l e r , 1 9 7 5 ) , and can be q u i t e a c i d i c (pH = 3 . 5 t o 4 . 5 ) ( K l i n k a and Lowe, 1 9 7 5 ) . They are seldom d e e p l y f r o z e n and thus remain porous and w e l l d r a i n e d a l l year l o n g . A . 3 . 4 C l i m a t e C l i m a t e here i s marine, warm temperate r a i n y , w i t h no d i s t i n c t d r y season. N e a r l y t h r e e - q u a r t e r s of the an n u a l p r e c i p i t a t i o n ( 2 2 0 cm t o 2 7 0 cm) f a l l s d u r i n g t he 8 month p e r i o d September t h r o u g h A p r i l , when fog and m i s t a r e a l s o common. At h i g h e l e v a t i o n s snow accumulates d u r i n g the w i n t e r months; o c c a s i o n a l l y snow f a l l s a t lower e l e v a t i o n s as w e l l , but seldom remains t h e r e f o r more than a week or two. Summer weather i s c o o l , w i t h average d a i l y a i r te m p e r a t u r e s u s u a l l y r e m a i n i n g below 2 0 °C. A . 3 _ . 5 V e g e t a t i o n Western hemlock (Tsuga h e t e r o p h y l l a ) and western r e d cedar . (Thuja p l i c a t a ) dominate the watershed v e g e t a t i o n c o v e r , w i t h r e d a l d e r ( A l n u s r u b r a ) and b l a c k cottonwood (Populus  t r i c h o c a r p a ) common a l o n g s i d e the w a t e r c o u r s e . At the stream's edge, v i n e maple (Acer c i r c i n a t u m ) , d e v i l ' s c l u b (Oplopanax 106 h o r r i d u s ) , salmonberry (Rubus s p e c t a b i l i s ) , and r e d h u c k l e b e r r y (VaccinTum p a r v i f o l i u m ) a r e a l l common (N. Rogers, p e r s . comm.). A.3.6 D i s t u r b a n c e h i s t o r y Mathewes (1973) has summarized the major watershed d i s t u r b a n c e s ( w i l d f i r e s , l o g g i n g , and burns) i n t h i s a r e a t o the year 1550 based upon sediment c o r e s taken from nearby Jacobs (Marion) Lake. The l a s t major d i s t u r b a n c e i n the watershed was a burn i n 1931. A.4_ Atmospheric i n p u t s A.4 .J_ D e p o s i t i o n m o n i t o r i n g To date t h e r e a re no p u b l i s h e d r e p o r t s r e v i e w i n g p r e c i p i t a t i o n c h e m i s t r y i n B r i t i s h Columbia, d e s p i t e the e x i s t e n c e of d a t a f o r a number of s i t e s . The l o n g e s t c o n t i n u o u s p r e c i p i t a t i o n c h e m i s t r y r e c o r d i s f o r the U.B.C. Rese a r c h F o r e s t (1971 t o p r e s e n t ) , c o l l e c t e d by Dr. M i c h a e l F e l l e r of the F o r e s t r y Department. A.j_.2 P r e c i p i t a t i o n c h e m i s t r y A n a l y s e s of F e l l e r ' s hydrogen i o n d a t a f o r t h e - p e r i o d 1971-1980 ( B e r n a r d and F e l l e r 1983) r e v e a l e d : (1) a mean b u l k p r e c i p i t a t ion"pH = 4.66; (2) annual v a r i a t i o n s i n hydrogen i o n l o a d i n g s ( [ H + ] * p r e c i p i t a t i o n volume) between 0.25 and 0.58 kg H +/ha; (3) f o r the p e r i o d of r e c o r d , p r e c i p i t a t i o n - w e i g h t e d , mean monthly pH v a r i e s from a summer low of 4.49 t o a w i n t e r h i g h of 4.99; (4) the hydrogen i o n d e p o s i t i o n r a t e of 20-70 m mol/m 2/yr i s i n the same or d e r of magnitude as s o u t h e r n Canada, n o r t h e a s t e r n U.S.A., and sou t h e r n S c a n d i n a v i a . A.4.3_ Loa d i n g v s . c o n c e n t r a t i o n A n a l y s i s of d a t a from C a r n a t i o n Creek ( S c r i v e n e r , 1975), P o r t Hardy, T e r r a c e (S. N i k l e v a , Atmos. E n v i r o n . S e r v i c e , p e r s . Comm.), and Olympic N a t i o n a l Park ( J . G i b s o n , Nat. Atmos. Depos. Program, p e r s . Comm.) c o n f i r m s t h a t annual hydrogen i o n l o a d i n g s (see S e c t . A.4.2) i n c o a s t a l r e g i o n s of the P a c i f i c Northwest a r e on the same o r d e r of magnitude as th o s e g e o g r a p h i c a r e a s e x p e r i e n c i n g a c i d p r e c i p i t a t i o n problems. The p r i m a r y d i f f e r e n c e l i e s i n the f a c t t h a t the per volume hydrogen i o n c o n c e n t r a t i o n i n the P a c i f i c Northwest i s r o u g h l y 1/2 t h a t found i n the t r o u b l e d a r e a s , w h i l e p r e c i p i t a t i o n volume i s n e a r l y d o u b l e . 107 A C u r r e n t impacts D e s p i t e s u r p r i s i n g l y h i g h hydrogen i o n l o a d i n g s i n t h i s r e g i o n no f i r m e v i d e n c e y e t e x i s t s t o suggest t h a t l a k e s and streams are b e i n g a d v e r s e l y a f f e c t e d by these l e v e l s of a c i d d e p o s i t i o n . In f a c t , f o r E u n i c e Lake i n the U.B.C. Res e a r c h F o r e s t (2 km NW of M a y f l y C r e e k ) , Marmorek (1984) c o u l d f i n d no e v i d e n c e t o suggest t h a t the l a k e had been c h e m i c a l l y a l t e r e d by a c i d i c p r e c i p i t a t i o n . I have examined c h e m i c a l d a t a f o r over 60 c o a s t a l w a t e r c o u r s e s i n B r i t i s h Columbia and, p l o t t i n g them a c c o r d i n g t o the method of G i b b s (1970), I found no e v i d e n c e t o suggest t h a t t h e i r c h e m i s t r y i s even p r e c i p i t a t i o n dominated. F u r t h e r m o r e , background c o n c e n t r a t i o n s f o r C a + , Mg + and a l k a l i n i t y a t M a y f l y Creek a r e c l o s e t o the t h e o r e t i c a l v a l u e s f o r w a t e r s u n a f f e c t e d by a c i d i f i c a t i o n (NRCC 1981). N e v e r t h e l e s s , F e l l e r (1975) found t h a t stream pH i n nearby E a s t Creek responded t o a c i d i c r a i n f a l l e v e n t s ; a d d i t i o n a l l y , the l o w e s t pH v a l u e s i n t h i s s tream were g e n e r a l l y r e c o r d e d d u r i n g the r a i n y w i n t e r months. However, even w i t h p r e c i p i t a t i o n pH v a l u e s below 5, the h i g h e s t H + c o n c e n t r a t i o n r e c o r d e d i n h i s s t u d y streams was pH 6.5. R e c e n t l y , C o l e (1984) r e p o r t e d t h a t i n a r e d a l d e r ecosystem i n Washington s t a t e , n i t r i f i c a t i o n i n n a t u r a l l y N - r i c h s o i l r e l e a s e d more p r o t o n s than a r e t y p i c a l of a r e a s r e c e i v i n g heavy a t m o s p h e r i c H + d e p o s i t i o n . H + l e a c h i n g , however, was l i m i t e d t o the t o p 40 cm. These H + l e a c h i n g r e s u l t s are i n l i n e w i t h an e a r l i e r s t u d y , a l s o i n Washington s t a t e , where r e s e a r c h e r s found no e f f e c t of " a c i d p r e c i p i t a t i o n " on s o i l s o l u t i o n i n a Douglas f i r ecosystem ( C o l e and Johnson 1977). Because of the h i g h o r g a n i c c o n t e n t of f o r e s t s o i l s i n t h i s g e o g r a p h i c a l r e g i o n , a n i o n a d s o r p t i o n i s p r o b a b l y m i n i m a l (Johnson and C o l e 1980). Thus, even i n c o a s t a l watersheds exposed t o marine s u l f a t e s , i t i s u n l i k e l y t h a t m o b i l e a n i o n s , such as s u l f a t e , w i l l a c c u m u l a t e . S i n c e c a t i o n l e a c h i n g i s l i m i t e d by the a v a i l a b i l i t y of m o b i l e a n i o n s (Johnson and C o l e 1980), i t appears t h a t f o r e s t ecosystems a l o n g t h e B.C. Coast ar e l e s s s u s c e p t a b l e t o a c i d i f i c a t i o n than the low b u f f e r i n g c a p a c i t y of the p a r e n t g e o l o g i c a l m a t e r i a l s would i n d i c a t e . 108 APPENDIX B. EXPERIMENTAL FIELD METHODS: DESIGN, CONSTRUCTION. AND APPLICATION OUTLINE B. 1 Stream d o s i n g B.2 D r i f t s a m p l i n g B.3 P h y s i c a l measurements B.3.1 Water movement and depth B.4 Chemical parameters B. 4.1 Aluminum B.4.2 Hydrogen i o n B.4.3 A l k a l i n i t y B.4.4 D i s s o l v e d oxygen B.4.5 M e t a l s B._1_ Stream d o s i n g Stream c h e m i s t r y was a l t e r e d by c a r e f u l l y a d d i n g d i l u t e s o l u t i o n s of e i t h e r HCl or A1C1 3 d i r e c t l y t o the r u n n i n g w a t e r s at the upstream end of a 1.5 m r i f f l e , t h e r e b y e n s u r i n g r a p i d m i x i n g . An 80 L f i b e r g l a s s tank f i t t e d w i t h a t e f l o n / g l a s s v a l v e a l l o w i n g p r e c i s e manual c o n t r o l of d o s i n g r a t e s was used to d e l i v e r s t o c k s o l u t i o n s . Stream pH was c o n t i n u a l l y m o n i t o r e d and a d d i t i o n r a t e s v a r i e d as n e c e s s a r y . P e r i o d i c a l l y the tank was r e f i l l e d w i t h f r e s h l y p r e p a r e d s t o c k s o l u t i o n . S o l u t i o n concentrations.... were chosen w i t h f i v e c o n s i d e r a t i o n s i n mind: (.1) a c i d - p u l s i n g ; (2) r e s e r v o i r s i z e ; (3) d e s i r e d stream pH; (4) d e l i v e r y r a t e , and (5) f r e q u e n c y of s o l u t i o n m i x i n g . The d e s i r e d o b j e c t i v e was a s o l u t i o n w i t h the l o w e s t p r a c t i c a b l e c o n c e n t r a t i o n , t h e r e b y m i n i m i z i n g the p o s s i b i l i t y of problems w i t h a c i d p u l s i n g , a c i d plumes (denser a c i d s o l u t i o n f a i l i n g t o mix p r o p e r l y ) and r e l e a s e of exchangeable i o n s from b e n t h i c a r e a s exposed t o hydrogen i o n c o n c e n t r a t i o n s above the d e s i g n p a r a m e t e r s . E x p e r i m e n t a l s o l u t i o n s were p r e p a r e d by m i x i n g r e a g e n t grade c h e m i c a l s w i t h f i l t e r e d (300 ixm) stream water. I t was n e c e s s a r y t o f i l t e r the water t o a v o i d c l o g g i n g the t e f l o n v a l v e w i t h minute o r g a n i c p a r t i c l e s . C o n c e n t r a t e d HCl ( A l l i e d Chemical) and h y d r a t e d A1C1 3 c r y s t a l s (BDH) were used i n s o l u t i o n p r e p a r a t i o n . On August 25, 1982, a 0.25 N HCl s o l u t i o n was p r e p a r e d by a d d i n g 1.6 L of c o n c e n t r a t e d HCl t o 80 L f i l t e r e d stream w a t e r . The aluminum s o l u t i o n on August 26 was p r e p a r e d by m i x i n g 500 gm h y d r a t e d A1C1 3 w i t h 1.2 L HCl and a d d i n g t h i s t o 80 L f i l t e r e d stream w a t e r . A s a t u r a t e d s o l u t i o n of anhydrous c a l c i u m c a r b o n a t e i n water was s l o w l y d r i p p e d i n t o the stream below the e x p e r i m e n t a l s e c t i o n t o r a i s e the pH i n M a y f l y Creek t h e r e b y a v o i d i n g impacts to f i s h and o t h e r b i o t a i n Jacobs Creek. 109 B.2 Dr i f t sampling In l i g h t of known d r i f t p a t t e r n s at. t h i s s i t e (see S e c t . A. 2 ) , and i n r e c o g n i t i o n of the many v a r i a b l e s a t t r i b u t e d t o i n i t i a t i n g , d r i f t (Waters 1972), I d e c i d e d t o conduct e x p e r i m e n t s d u r i n g d a y l i g h t hours t o m i n i m i z e c o m p l i c a t i n g f a c t o r s such as n o c t u r n a l b e h a v i o r a l d r i f t . A d d i t i o n a l l y , e x p e r i m e n t s were c a r r i e d out d u r i n g p e r i o d s of r e l a t i v e l y s t a b l e f l o w t o m i n i m i z e the i n f l u e n c e of " c a t a s t r o p h i c " d r i f t . D r i f t i n g i n v e r t e b r a t e s were sampled u s i n g custom d e s i g n e d , t a p e r i n g n e t s f i t t e d w i t h 86 Mm N i t e x mesh. T h i s s i z e net was chosen because the pores are s m a l l enough t o c a p t u r e e a r l y i n s t a r c h i r o n o m i d l a r v a e (Mundie 1971), and y e t not t r a p most s i l t or c l a y (< 62 nm). Such a net s h o u l d a l s o c a p t u r e the m a j o r i t y of Ephemeroptera, as w e l l , s i n c e even t h e i r eggs a r e g e n e r a l l y > 90 Mm i n the narrowest d i m e n s i o n ( E l l i o t t and Humpesch 1980). Each d r i f t net was 95 cm l o n g w i t h 77 cm of N i t e x n e t t i n g a t t a c h e d t o a f a b r i c c o l l a r w i t h v e l c r o f l a p s t o f a c i l i t a t e a t t a c h i n g the net t o square PVC p i p e frames (15 cm by 15 cm) f i l l e d w i t h sand t o a v o i d buoyancy problems. Nets were h e l d i n p l a c e by v e r t i c a l m e t al rods i m p l a n t e d i n t h e stream bottom. To a v o i d d i s t u r b i n g the benthos, a c c e s s t o the nets was v i a s m a l l b r i d g e s a t t a c h e d t o stream banks. D r i f t samples were taken every 1.5 h r s . by l o w e r i n g a net on the rods u n t i l the frame came i n t o c o n t a c t w i t h the benthos; a t the end of a s p e c i f i e d p e r i o d , the net was r a i s e d and removed from the stream. Net c o n t e n t s were then r i n s e d i n t o p l a s t i c bags, f o r m a l i n was added t o a p p r o x i m a t e l y 10%, and the bags h e a t - s e a l e d , l a b e l e d , and packed f o r s t o r a g e . R e p l i c a t e samples were taken d u r i n g each c o l l e c t i o n p e r i o d by s i m u l t a n e o u s l y p l a c i n g two n e t s s i d e - b y - s i d e . A l t h o u g h t h i s method f a i l s t o p r o v i d e t r u e r e p l i c a t e samples as r e q u i r e d by i n f e r e n t i a l s t a t i s t i c s , i t does f o l l o w what H u r l b e r t (1984) r e f e r s t o as an " o p t i m a l impact study d e s i g n " where the " r e s u l t s are so c l e a r t h a t i n f e r e n t i a l s t a t i s t i c s a r e not r e q u i r e d " . B.3 P h y s i c a l measurements B. 3.J_ Water movement and depth Water v e l o c i t y was measured at each net p o s i t i o n u s i n g a c a l i b r a t e d O t t c u r r e n t meter w i t h an e l e c t r o - m e c h a n i c a l c o u n t e r (Model C-2). Mean v e l o c i t y was c a l c u l a t e d from r e p l i c a t e , 30 second r e a d i n g s . T y p i c a l l y , measurements were made a t both the s t a r t and f i n i s h of a net c o l l e c t i o n p e r i o d , but s e v e r a l extended t r i a l s were run t o determine the r a t e a t which 1 c l o g g i n g took p l a c e and i t s e f f e c t on v e l o c i t y measurements. Problems w i t h water b e i n g d i v e r t e d around the net o p ening as a r e s u l t of c l o g g i n g were a v o i d e d by always p l a c i n g the c u r r e n t meter w i t h 1 10 the i m p e l l e r 5 cm i n s i d e the net t h r o a t . At each net p o s i t i o n , water depth was a l s o r e c o r d e d f o r use i n volume f i l t r a t i o n c a l c u l a t i o n s . To monitor changes i n d i s c h a r g e , s t a g e measurements were r e c o r d e d t w i c e d a i l y from a f i x e d - p o s i t i o n gauge a t the lower end of the study a r e a . B.3_.2 Temperature Both water and a i r temperature were r e c o r d e d t h r e e t i m e s d a i l y . In a d d i t i o n , a submerged Ryan thermograph p r o v i d e d c o n t i n u o u s water temperature measurements. B._3._3 S u n r i s e / s u n s e t D u r i n g the study p e r i o d o f f i c i a l s u n r i s e t i m e s (PST) ranged from 0502 hours on June 19 t o 0625 h r s on August 30; c o r r e s p o n d i n g sunset times were 2124 h r s . and 2000 h r s . (Vancouver P l a n e t a r i u m , p e r s . comm.). B.4 Chemical parameters W i t h the e x c e p t i o n of hydrogen i o n s , which were c o n t i n u o u s l y m o n i t o r e d , a l l o t h e r c h e m i c a l s a m p l i n g was done on the b a s i s of grab samples taken a t some time d u r i n g t h e e x p e r i m e n t a l p e r i o d . B.£.J_ Aluminum Two forms of aluminum were de t e r m i n e d i n t h i s e x p e r i m e n t : (1) d i s s o l v e d , monomeric aluminum, and (2) t o t a l aluminum. T o t a l added aluminum was c a l c u l a t e d based upon stream water c h l o r i d e c o n c e n t r a t i o n s (see S e c t . D.3.1), w h i l e samples f o r d i s s o l v e d , monomeric aluminum were c o l l e c t e d i n the f i e l d . These samples r e q u i r e d prompt f i e l d e x t r a c t i o n s because even 0.1 Mm f i l t r a t i o n f a i l s t o remove a l l p o l y m e r i c and p a r t i c u l a t e A l 3 + (Barnes 1975). E x t r a c t i o n s were c a r r i e d out on f i l t e r e d (0.45 um), 400 mL water samples a c c o r d i n g t o the methods i n Barnes (1975). The methyl i s o b u t y l ketone e x t r a c t s were s t o r e d i n new, acid-washed, 150 mL p o l y e t h y l e n e c o n t a i n e r s a t 10 °C u n t i l a n a l y z e d . B.4.2 Hydrogen i o n For t h e s e experiments a C o r n i n g c a l o m e l c o m b i n a t i o n e l e c t r o d e (No. 476182) was a t t a c h e d t o a H o r i z o n pH C o n t r o l l e r (Model 5997-20) w i t h manual temperature compensation; r e s u l t s were r e c o r d e d on a R u s t r a k s t r i p - c h a r t r e c o r d e r . To a v o i d s t r e a m i n g p o t e n t i a l s (ASTM 1981) and p r o v i d e p r o t e c t i o n from d r i f t i n g d e b r i s , the probe was f i t t e d w i t h a s t a i n l e s s s t e e l f l o w chamber grounded t o the stream bed. The system was c a l i b r a t e d a t l e a s t d a i l y u s i n g F i s h e r c e r t i f i e d b u f f e r s o l u t i o n s and manual temperature compensation. For c o n t i n u o u s m o n i t o r i n g of stream water pH i n t h e 1.11 e x p e r i m e n t a l zone, the e l e c t r o d e was p o s i t i o n e d 10 m downstream from the d o s i n g s i t e . At l e a s t d a i l y , a water sample from above the d o s i n g s i t e was checked f o r pH and p e r i o d i c a l l y water samples from s e v e r a l s i t e s below the study a r e a were ta k e n t o moni t o r a c i d plume d i s p e r s i o n . S u b g r a v e l pH was o c c a s i o n a l l y checked u s i n g a PVC s t a n d p i p e sunk 50 cm i n t o the s t r e a m s i d e sediments. B.4.3 A l k a l i n i t y A l k a l i n i t y measures the a b i l i t y of an aqueous s o l u t i o n t o n e u t r a l i z e a c i d ; a n other name f o r t h i s i s a c i d n e u t r a l i z i n g c a p a c i t y (ANC). Immediately f o l l o w i n g c o l l e c t i o n of a 500 mL water sample, a l k a l i n i t y was d e t e r m i n e d u s i n g the Gran t i t r a t i o n method (see Stumm and Morgan 1970). Samples were p l a c e d i n a 535 mL c a p a c i t y g l a s s - s t o p p e r e d b o t t l e c o n t a i n i n g a magnetic s p i n n e r . The pH probe was lowered i n t o the b o t t l e ' s t h r o a t , and a b u r e t t e c o n t a i n i n g c e r t i f i e d HCl s o l u t i o n (N/200) was p o s i t i o n e d overhead t o a l l o w a c i d d e l i v e r y d i r e c t l y i n t o t h e v e s s e l . W h i l e g e n t l y s t i r r i n g the s o l u t i o n , I d e r i v e d a t i t r a t i o n c u r v e by a d d i n g HCl one mL a t a time and t a k i n g pH measurements a t r e g u l a r i n t e r v a l s . A l t h o u g h t h i s method d i d not p r o v i d e a c l o s e d c e l l , as recommended by S c h i n d l e r and R u s z c z y n s k i (1983), i t d i d g r e a t l y reduce sample s u r f a c e a r e a exposed t o the atmosphere. B.4.4 D i s s o l v e d oxygen D i s s o l v e d oxygen d e t e r m i n a t i o n s were made on 65 mL water samples u s i n g Hach K i t model AL-36B. B.4.5 M e t a l s Water samples- f o r m u l t i - e l e m e n t ICP a n a l y s i s (see S e c t . G.1.3.4.1) were s t o r e d i n new, 150 mL p o l y e t h y l e n e b o t t l e s t h a t had p r e v i o u s l y been acid-washed a c c o r d i n g t o t h e methods o u t l i n e d i n EPA (1983). Each c o n t a i n e r r e c e i v e d 2 mL of c o n c e n t r a t e d , u l t r a p u r e HN0 3 t o ensure t h a t m e t a l s would remain i n s o l u t i o n and not become adsorbed onto the c o n t a i n e r w a l l s . Most stream water samples were f i l t e r e d t h r o u g h 0.45 um M i l l i p o r e f i l t e r s p r i o r t o b e i n g b o t t l e d . However, some samples were l e f t u n f i l t e r e d t o p e r m i t d e t e r m i n a t i o n of t o t a l m e t a l l o a d . Samples were s t o r e d a t 10 °C u n t i l a n a l y z e d . U n f i l t e r e d water samples f o r d i s s o l v e d c h l o r i d e a n a l y s e s and e l e c t r i c a l c o n d u c t i v i t y were c o l l e c t e d i n acid - w a s h e d , 1 L l i n e a r p o l y e t h y l e n e c o n t a i n e r s and s t o r e d a t 10 °C u n t i l a n a l y z e d . D u r i n g each s a m p l i n g p e r i o d , water samples were always p a i r e d , w i t h one o r i g i n a t i n g from the c o n t r o l s e c t i o n , and the o t h e r from the e x p e r i m e n t a l s e c t i o n . 1 12 APPENDIX C. EXPERIMENTAL LABORATORY METHODS: DESIGN, CONSTRUCTION AND APPLICATION OUTLINE C.1 Overview C.2 A r t i f i c i a l streams C.3 D o s i n g a p p a r a t u s C.4 C h e m i c a l s o l u t i o n s and d e l i v e r y C.5 A n i m a l s C.6 Response measurement C.7 Water c h e m i s t r y C._1_ Overview Because n e i t h e r s t a n d a r d equipment nor methods were a v a i l a b l e f o r examining s u b l e t h a l e f f e c t s of c h e m i c a l s u b s t a n c e s on l o t i c m i c r o - i n v e r t e b r a t e s (< 2 mm), I d e s i g n e d a method f o r e x p o s i n g a q u a t i c a n i m a l s t o water w i t h a known c h e m i s t r y . As the measure of b e h a v i o r a l response I chose t o use number of a n i m a l s d r i f t i n g per t i m e . T h i s , i n t u r n , n e c e s s i t a t e d the d e s i g n and c o n s t r u c t i o n of a r t i f i c i a l stream c h a n n e l s i n which such e x p e r i m e n t s c o u l d be c a r r i e d o u t . The purpose of t h i s a p pendix i s t o p r o v i d e d e t a i l s on d e s i g n , cons'truct i o n , and o p e r a t i o n of the r e s u l t i n g e x p e r i m e n t a l f a c i l i t y . C.2_ A r t i f i c i a l streams F i f t e e n a r t i f i c i a l stream c h a n n e l s measuring 3.7 cm wide, 60 cm l o n g and 3 cm deep were c o n s t r u c t e d from p l e x i g l a s s . These were b u i l t as 5 a r t i f i c i a l stream u n i t s , each c o n s i s t i n g of 3 c h a n n e l s s e p a r a t e d by 1 cm d i v i d e r s ( F i g . C.1). Four of the stream u n i t s (12 c h a n n e l s ) were devoted t o e x p e r i m e n t a t i o n , w h i l e the r e m a i n i n g u n i t (3 c h a n n e l s ) was r e s e r v e d as an a n i m a l -h o l d i n g f a c i l i t y . The base of each c h a n n e l was l i n e d w i t h h i g h - d e n s i t y s t y r o f o a m (0.6 cm t h i c k ) , and a t the downstream end was a s m a l l p l a s t i c box c o n t a i n i n g two o u t l e t h o l e s c o v e r e d by 86 nm N i t e x n e t t i n g . F i l t e r e d water dropped i n t o an aluminum t r o u g h f o r d i s p o s a l t h r o u g h the f l o o r d r a i n . Each c h a n n e l was equipped w i t h a p l a s t i c header box (2 cm wide, 3.5 cm deep and 5 cm long) w i t h h o l e s i n the bottom t o promote even water d i s t r i b u t i o n over the w i d t h of the c h a n n e l . A f l o w volume of 970 mL/min was m a i n t a i n e d i n each c h a n n e l ; t h i s gave a water depth of a p p r o x i m a t e l y 4 mm over the s u b s t r a t e when the stream a n g l e was at 2 d e g r e e s . Streams were housed i n a w a l k - i n e n v i r o n m e n t a l chamber where the temperature was m a i n t a i n e d a t 13 °C. 1 1 3 F i g u r e C.1 T e s t i n g a p p a r a t u s : Schematic diagram (not to s c a l e ) . T h i s schematic i s f o r one e x p e r i m e n t a l stream b l o c k ; i n use, t h e r e were f o u r such b l o c k s of 3 c h a n n e l s each. D e c h l o r i n a t e d water e n t e r e d the c o n s t a n t - l e v e l head tank; from t h e r e , two o u t l e t s per stream c h a n n e l c a r r i e d water t o a s m a l l head box and u l t i m a t e l y i n t o the stream c h a n n e l . The main l i n e c a r r i e d a p p r o x i m a t e l y 830 mL/min, w h i l e the secondary l i n e c a r r i e d c a . 140 mL/min. The secondary l i n e emptied i n t o a m i x i n g chamber where s o l u t i o n s were i n t r o d u c e d from a p e r i s t a l t i c pump at the r a t e of =8 mL/min. Water e x i t i n g each channel was f i l t e r e d t h r ough 86 /im mesh n e t s i n removable f i l t e r boxes. .1^ So e o * e 1 15 C.J3 D o s i n g a p p a r a t u s D e c h l o r i n a t e d water (from the U.B.C. Zoology Dept.) f i r s t e n t e r e d a 20 L p l e x i g l a s s c o n s t a n t - h e a d tank equipped w i t h 30 o u t l e t hoses (two per stream c h a n n e l ) and an o v e r f l o w . For each stream c h a n n e l the main s u p p l y l i n e d e l i v e r e d water (900 mL/min) d i r e c t l y from the head tank t o the header box, w h i l e the second l i n e (70 mL/min) f l o w e d i n t o a p l e x i g l a s s m i x i n g chamber (one per c h a n n e l ) where t e s t s o l u t i o n s were i n t r o d u c e d . A f t e r b e i n g d i l u t e d t o the d e s i r e d c o n c e n t r a t i o n , s o l u t i o n s e x i t e d the m i x i n g chamber and e n t e r e d the header box where they mixed w i t h water d e l i v e r e d from the m a i n l i n e . S u b s e q u e n t l y the f i n a l water s u p p l y then f l o w e d i n t o the stream c h a n n e l . T h i s set-up ensured (1) c o n s t a n t f l o w i n each stream of (2) w e l l a e r a t e d water w i t h (3) a t m o s p h e r i c gases i n a t m o s p h e r i c , and (4) a c o n s t a n t t e m p e r a t u r e . I t a l s o p e r m i t t e d independent c o n t r o l of water c h e m i s t r y i n each stream c h a n n e l . C.4 Chemical s o l u t i o n s and d e l i v e r y T e st s o l u t i o n s were p r e p a r e d u s i n g a n a l y t i c a l grade r e a g e n t s - - c o n c e n t r a t e d HCL, A1C1 3.6H 20, c o n c e n t r a t e d H 2SO f l, and c h o l i n e c h l o r i d e ([CH 2(OH).CH 2.N(CH 3) 3 ] C 1 ) — and d e l i v e r e d t o m i x i n g chambers u s i n g a p e r i s t a l t i c pump. S o l u t i o n c o n c e n t r a t i o n s were de t e r m i n e d e m p i r i c a l l y t o y i e l d r e q u i r e d c o n c e n t r a t i o n s i n t e s t c h a n n e l s w i t h a n i m a l s a b s e n t . I t was assumed t h a t a d d i n g a n i m a l s would not s i g n i f i c a n t l y a l t e r water c h e m i s t r y . The p r o t o c o l f o r s o l u t i o n a d d i t i o n s was as f o l l o w s : (1) R e q u i r e d water c h e m i s t r y i n each c h a n n e l was determined based upon t h e s t a t i s t i c a l d e s i g n . (2) Stock s o l u t i o n s were i n i t i a l l y mixed a c c o r d i n g t o t h e o r e t i c a l c a l c u l a t i o n s ; t h e n , i n the absence of a n i m a l s , e m p i r i c a l t e s t runs were c a r r i e d out t o c a l i b r a t e d e l i v e r y r a t e s . When n e c e s s a r y , s t o c k s o l u t i o n s were remixed and d e l i v e r y r a t e s r e a d j u s t e d t o p r o v i d e the d e s i r e d water c h e m i s t r y i n each c h a n n e l . Once the d e l i v e r y system was c a l i b r a t e d t o " a u t o m a t i c a l l y " a d j u s t water c h e m i s t r y as d e s i r e d , e x p e r i m e n t s were i n i t i a t e d . (3) Each experiment s t a r t e d by t u r n i n g the p e r i s t a l t i c pumps o f f and c l o s i n g a v a l v e on the m i x i n g chambers. To t h o r o u g h l y f l u s h the stream c h a n n e l s , d e c h l o r i n a t e d water was a l l o w e d t o c o n t i n u e f l o w i n g f o r 30 min b e f o r e a n i m a l s were i n t r o d u c e d . (4) A f t e r a d d i n g a n i m a l s an a d d i t i o n a l 30 min were a l l o w e d f o r a c c l i m a t i o n , and a t the end of t h i s p e r i o d , (5) the v a l v e was reopened and the pumps t u r n e d on. (6) A n i m a l s and water c h e m i s t r y were then sampled a t the c o n c l u s i o n of the 3 hour exposure p e r i o d . 1 1 6 C.5 An i m a l s S p r i n g Creek i n v e r t e b r a t e s were c o l l e c t e d d u r i n g d a y l i g h t hours u s i n g 86 /xm N i t e x d r i f t n e t s and s e p a r a t e d from l a r g e a n i m a l s (> 2 mm) and d e t r i t a l p a r t i c l e s by g e n t l y washing through 1.7 mm and 287 /um s i e v e s . T h i s c o m b i n a t i o n of d r i f t net and 287 Mm s i e v e was used i n p r e v i o u s e x p e r i m e n t s and the e f f i c i e n c y has been d e t e r m i n e d (see S e c t . D.1.2.1). F o l l o w i n g c a p t u r e and s o r t i n g , a n i m a l s were q u i c k l y t r a n s p o r t e d from the f i e l d t o t h e l a b o r a t o r y where they were p l a c e d i n stream c h a n n e l s s p e c i a l l y d e s i g n a t e d as h o l d i n g chambers. On the morning of t h e e x p e r i m e n t , a n i m a l s were removed from the h o l d i n g c h a n n e l s and p l a c e d i n p e t r i d i s h e s where they were counted out u s i n g a d i s s e c t i n g m i c r o s c o p e ; the s i z e range of a n i m a l s s e l e c t e d was a l s o r e c o r d e d . Nine c h i r o n o m i d s were p l a c e d i n each randomly chosen c h a n n e l and, as d e s c r i b e d e a r l i e r , e x p e r i m e n t a l a d d i t i o n s commenced 30 min a f t e r a l l c h a n n e l s were s t o c k e d . C.6 Response measurement Water e x i t i n g each c h a n n e l was f i l t e r e d t h r o u g h 86 Mm mesh t o c a p t u r e d r i f t i n g a n i m a l s . Nets were i n s t a l l e d p r i o r t o s t o c k i n g a n i m a l s ; they were then removed a t the end of 3 h o u r s , f o l l o w i n g the 30 min a c c l i m a t i o n p e r i o d and p r i o r t o i n t r o d u c i n g the t e s t s o l u t i o n s . At t h e end of the exposure p e r i o d , the n e t s were removed and a n i m a l s c a r e f u l l y r i n s e d i n t o a p e t r i d i s h , c o u n t e d , and l i v e a n i m a l s h e l d f o r 48 hours t o p e r m i t f u r t h e r o b s e r v a t i o n of m o r t a l i t y . C.7 Water c h e m i s t r y Background v a l u e s were based upon s i n g l e grab samples drawn a t the s t a r t of each e x p e r i m e n t from c o n t r o l c h a n n e l s . Water c h e m i s t r y i n each e x p e r i m e n t a l c h a n n e l was d e t e r m i n e d from grab samples taken 2.5 hours a f t e r s o l u t i o n a d d i t i o n s commenced. 1 17 APPENDIX D. ANALYTICAL METHODS OUTLINE D.1 B i o t i c samples D.1.1 Taxonomic i d e n t i f i c a t i o n D.1.2 S o r t i n g and enumeration D.1.2.1 Method e v a l u a t i o n D.2 P h y s i c a l ' c h a r a c t e r i s t i c s D.2.1 S t a n d a r d i z i n g f i l t e r e d volume D.2.2 C o n d u c t i v i t y measurements D.3 Ch e m i c a l a n a l y s e s D.3.1 Aluminum D.3.2 C h l o r i d e D.3.3 A l k a l i n i t y D.3.4 M e t a l s D.4 S t a t i s t i c s D.5 Computing D.J_ B i o t a D.______ Taxonomic i d e n t i f i c a t i o n Because most a n i m a l s c a p t u r e d were e x t r e m e l y s m a l l , w i t h e a r l y i n s t a r s p r e d o m i n a t i n g , taxonomic i d e n t i f i c a t i o n was c o n s t r a i n e d t o o r d e r . Ephemeroptera, P l e c o p t e r a , and c h i r o n o m i d s were f u r t h e r s u b d i v i d e d i n t o s i z e c l a s s e s (> 2 mm = l a r g e ) based upon t o t a l body l e n g t h . In a l l , 10 groups were enumerated: l a r g e and s m a l l P l e c o p t e r a , l a r g e and s m a l l Ephemeroptera, l a r g e and s m a l l Chironomidae ( D i p t e r a ) , T r i c h o p t e r a , H y d r a c a r i n a , H a r p a c t a c o i d a (Copepoda), and Simulium ( S i m u l i i d a e : D i p t e r a ) . N u m e r i c a l l y , t h e s e groups made up > 95 % of a l l d r i f t i n g a n i m a l s c a p t u r e d . D.J_.2 S o r t i n g and enumeration Because l a r g e numbers of o r g a n i c p a r t i c l e s were t r a p p e d i n the 86 jum mesh d r i f t n e t s , i t was n e c e s s a r y t o s e p a r a t e a n i m a l s from d e b r i s b e f o r e enumerating the samples. Thus, p r e s e r v e d d r i f t samples were p r o c e s s e d by s i e v i n g t h r ough a 296 Mm mesh and r e t a i n i n g the f i l t r a t e . A l l a n i m a l s r e t a i n e d on the s i e v e were then examined under 25X and i d e n t i f i e d , c o u n t e d , removed, and p r e s e r v e d . E x u v i a e and head c a p s u l e s were e x c l u d e d from the count and s e a r c h i n g ceased when no more a n i m a l s were found a f t e r 2 minutes of e x a m i n a t i o n . 1 18 D._j_.2.__ Method e v a l u a t i o n To d e t e r m i n e l a b o r a t o r y " l o s s " v i a f i l t e r i n g w i t h a 296 Mm mesh, the f i l t r a t e was subsampled and counted u s i n g methods developed by Mundie (1971). T h i s i n v o l v e d p l a c i n g 21 s h e l l v i a l s on the bottom of a 500 mL beaker t o which 250 mL of tap water were then added. Next, the f i l t r a t e was c o n c e n t r a t e d , by s i e v i n g t h r o u g h a 56 Mm mesh, and then added t o the beaker w h i l e g e n t l y s t i r r i n g . A f t e r the a n i m a l s and p a r t i c l e s had s e t t l e d (> 1 h ) , the c o n t e n t s of a l l 21 v i a l s were examined i n d i v i d u a l l y ; a n i m a l s were i d e n t i f i e d and counted as o u t l i n e d i n the p r e v i o u s s e c t i o n . F i n a l l y , the number of a n i m a l s counted was m u l t i p l i e d by 2.0025 t o account f o r the f a c t t h a t the area sampled by a l l the v i a l s was o n l y 27.87 cm 2, compared w i t h 55.81 cm 2 f o r the beaker. R e s u l t s showed t h a t n e a r l y a l l l a r g e a n i m a l s (> 2 mm) c a p t u r e d i n the 86 Mm mesh d r i f t n e t s were r e t a i n e d on the 296 Mm mesh f i l t e r and more than 80 % of T r i c h o p t e r a and s m a l l P l e c o p t e r a were r e t a i n e d . However, the 296 Mm f i l t e r a l l o w e d up t o 60 % of s m a l l c h i r o n o m i d s , and up t o 40 % of s m a l l Ephemeroptera t o pass t h r o u g h . U s i n g these methods even h i g h e r numbers of H y d r a c a r i n a (> 75 % ) , and h a r p a c t a c o i d copepods (> 80 %) p a s s e d t h r o u g h . To p r e v e n t b i a s i n the a n i m a l c o u n t s , s t a n d a r d i z e d methods were used t o s e p a r a t e a n i m a l s from o r g a n i c d e b r i s p a r t i c l e s . As a r e s u l t of u s i n g 296 Mm f i l t e r s , d r i f t d e n s i t i e s r e p o r t e d i n t h i s study r e p r e s e n t c o n s e r v a t i v e e s t i m a t e s . Data p r e s e n t e d and a n a l y z e d i n Chapter 3 have not been " a d j u s t e d " f o r the l o s s . D.2 P h y s i c a l c h a r a c t e r i s t i c s D.2._1_ S t a n d a r d i z i n g f i l t e r e d volume In t h e o r y i t s h o u l d be p o s s i b l e t o d i r e c t l y c a l c u l a t e the. volume of water f i l t e r e d by each net i n M a y f l y Creek based upon i n i t i a l v e l o c i t y measurements. To do so would r e q u i r e e s t a b l i s h i n g r e l a t i o n s h i p s between (1) i n i t i a l and f i n a l v e l o c i t i e s , and (2) i n i t i a l v e l o c i t i e s and volume of water f i l t e r e d . P r e l i m i n a r y c a l c u l a t i o n s based upon d a t a c o l l e c t e d a t s i t e 1 on 19-27 August, 1982 show a p o s i t i v e c o r r e l a t i o n between i n i t i a l v e l o c i t y and 2700 second v e l o c i t y (y = 1.24X -0.22, r = 0.82). Such a r e l a t i o n s h i p i s p a r t i c u l a r l y v a l u a b l e f o r i n t e r p r e t i n g d a t a c o l l e c t e d on those d a t e s where o n l y i n i t i a l f l o w measurements were t a k e n , f o r i t a l l o w s volume c a l c u l a t i o n s t o be c a r r i e d o u t . The r e l a t i o n s h i p between i n i t i a l f l o w v e l o c i t y and volume f i l t e r e d was e s t a b l i s h e d as f o l l o w s . A r e g r e s s i o n , i n c o r p o r a t i n g i n i t i a l and f i n a l f l o w v e l o c i t y measurements, was1 c a l c u l a t e d and the r e s u l t s used i n e q u a t i o n D.I. j» = 1/2 m ( t + b/m) 2 - b 2/2 m Eq. D.1 where m = r e g r e s s i o n l i n e s l o p e 1 19 b = • r e g r e s s i o n l i n e i n t e r c e p t . T h i s y i e l d e d a v a l u e (T>) r e p r e s e n t i n g c u m u l a t i v e l i n e a r water movement through the n e t s . T h i s e q u a t i o n i s v a l i d o n l y i f the change i n water v e l o c i t y p a s s i n g t h r o u g h the n e t s i s c o n s t a n t . S i n c e the p r e v i o u s l y demonstrated r e l a t i o n s h i p was l i n e a r , i t i s assumed t h a t t h e r e was a c o n s t a n t d e c e l e r a t i o n i n water v e l o c i t y d u r i n g the p e r i o d n e t s were i n p l a c e ; hence, i t i s a c c e p t a b l e t o use e q u a t i o n D.1. V a l u e s f o r volume of water f i l t e r e d were c a l c u l a t e d s i m p l y by m u l t i p l y i n g the l i n e a r f a c t o r (fy) by the c r o s s - s e c t i o n a l area of the n e t s . F i n a l l y , a r e g r e s s i o n was c a l c u l a t e d r e l a t i n g i n i t i a l v e l o c i t y t o water volume f i l t e r e d . The a l g o r i t h m y = 20.67X - 2.01 Eq. D.2 gave a good f i t ( r = 0.93) f o r t h e s i t e 1 d a t a mentioned above; t h i s i n d i c a t e s t h e r e indeed was a d i r e c t r e l a t i o n s h i p between i n i t i a l v e l o c i t y and f i n a l volume of water f i l t e r e d . To c a l c u l a t e the volume of water f i l t e r e d a t each net p o s i t i o n f l o w v e l o c i t y was m u l t i p l i e d by the c r o s s - s e c t i o n a l a r e a of the net o p e n i n g . In c a s e s where the net was not f u l l y submerged, the c r o s s - s e c t i o n a l a r e a was a d j u s t e d a c c o r d i n g l y . V a l u e s were then compared t o the s t a n d a r d volume (10" L) and n e c e s s a r y c o r r e c t i o n f a c t o r s c a l c u l a t e d . V a l u e s used f o r each of the t h r e e f i e l d e x p e r i m e n t s a r e g i v e n i n T a b l e D.1. Column 5. c o n t a i n s f a c t o r s by which a n i m a l c o u n t s ..were m u l t i p l i e d t o a d j u s t them t o the s t a n d a r d volume. D.2_. 2 Conduct i v i t y measurements E l e c t r i c a l c o n d u c t i v i t y was d e t e r m i n e d on samples at 22 °C u s i n g a Radiometer meter (Model CDM-3); v a l u e s were then s t a n d a r d i z e d t o c o n d u c t i v i t y a t 25 °C. D.3 C hemical a n a l y s e s D. 3. J_ Aluminum F i e l d e x t r a c t i o n s f o r d i s s o l v e d , monomeric aluminum were a n a l y z e d u s i n g atomic a b s o r p t i o n methods. E x t r a c t s were a s p i r a t e d i n t o a n i t r o u s - o x i d e - a c e t y l e n e flame and atomic a b s o r b t i o n measured a t 309.4 nm on a J a r r e l l - A s h s p e c t r o p h o t o m e t e r f o r comparison w i t h blank and s t a n d a r d v a l u e s . Known s o l u t i o n s of 0, 12.5, 25, and 50 Mg A l / L were p r e p a r e d u s i n g d e i o n i z e d , d i s t i l l e d water and a s t a n d a r d s o l u t i o n (BDH) c o n t a i n i n g 1 mg Al/mL. T h i s method i s s u i t a b l e f o r waters w i t h aluminum c o n c e n t r a t i o n >1 ug/L (Barnes 1975). T o t a l added aluminum c o n c e n t r a t i o n s were c a l c u l a t e d based upon c h l o r i d e c o n c e n t r a t i o n s i n stream water samples. For each mole of C I " added t o the stream, 1/3 mole A l 3 + was a l s o added. Assuming C l " i s r e l a t i v e l y n o n - r e a c t i v e i n M a y f l y Creek ( v i z . t h e r e a r e no s i g n i f i c a n t s o u r c e s or s i n k s ) , the t h e o r e t i c a l , t o t a l amount of aluminum added can be c a l c u l a t e d 120 T a b l e D.1 Water volume f i l t e r e d : C o n v e r s i o n f a c t o r s , Experiment 1 Net P o s i t i o n 1 ,L 1 ,R 2,L 2,R 1 ,L 1 ,R 2,L 2 ,R 1 ,L 1 ,R 3,L 3, R 4, L 4,R Mean I n i t i a l V e l o c i t y (cm/sec) (SD,N) 14.62 (0.06,2) 12.01 (0.26,2) 11.81 (a (2.863,4) 9.47 (a 1 5.25 (2.12,3) 1 2.30 (1 .33,3) 11.81 (a (2.86,4) 9.47 (a (2.84,4) 1 4.84 1 1 .06 4.85 4.30 17.71 13.69 C r o s s Sect i o n a l Area (cm 2) 225 225 172.5 1 65 Experiment 2. 225 225 172.5 1 65 Experiment 3. 225 225 1 65 225 1 04 90 Volume F i l t e r e d ( 1 0 3 L/ 45 min) 8.88 7.30 5.55 4.22 9.26 7.47 5.50 4.22 6.72 9.02 2.61 2.1 6 4.95 3.33 C o n v e r s i o n F a c t o r 1.126 1 .371 1.818 2.370 1 .080 1 .338 1.818 2.370 1 . 109 1 .488 12.500 10.341 5.456 8.117 (a P o o l e d v a l u e s f o r 25, 26 August 121 from t h e i n c r e m e n t a l C l " c o n c e n t r a t i o n . D.3.2 C h l o r i d e C h l o r i d e c o n c e n t r a t i o n s were d e t e r m i n e d by t i t r a t i o n w i t h m e r c u r i c n i t r a t e (APHA 1984) s t a n d a r d i z e d w i t h a known sodium c h l o r i d e s o l u t i o n and compared w i t h d e i o n i z e d , d i s t i l l e d water b l a n k s . D e t e c t i o n l i m i t s on t h i s t e s t a r e around 0.1 mg/L. D.3_.3_ A l k a l i n i t y A c c o r d i n g t o the methods of Gran (see Stumm and Morgan 1970), t i t r a t i o n d a ta were p l o t t e d , and a l k a l i n i t y d e t e r m i n e d , u s i n g t h e s e e q u a t i o n s : F = ( V 0 + v) [ H + ] Eq. D.3 where F = d e r i v e d l i n e a r f u n c t i o n V 0 = o r i g i n a l volume of sample (mL) v = volume of s t r o n g a c i d added (mL) AT = v (N * 50,000) / V 0 Eq. D.4 where Ar = t o t a l a l k a l i n i t y (as CaC0 3) (mg/L) Ae = AT/5.004*10" 2 Eq. D.5 where Ae = a l k a l i n i t y (Meq/L) D.3.4 M e t a l s Water samples and d e i o n i z e d , d i s t i l l e d b l a n k s ( a l l c o n t a i n i n g 2 mL u l t r a p u r e HN0 3) were c o n c e n t r a t e d by e v a p o r a t i n g t o < 50 mL a t 40 °C. The p r e s ence of HN0 3 i n the sample ensured t h a t i o n s remained i n s o l u t i o n even a f t e r e v a p o r a t i o n (M. B l a d e s , UBC C h e m i s t r y Dept., P e r s . comm.). Samples were then sent t o ACME A n a l y t i c a l L a b o r a t o r i e s , Vancouver, B.C. f o r m u l t i - e l e m e n t i n d u c t i v e l y c o u p l e d plasma s p e c t r o p h o t o m e t r i c (ICP) a n a l y s i s . D e t e c t i o n l i m i t s on the ICp a n a l y s e s were 0.01 mg/L f o r A l and K, 0.02 mg/L f o r Ca and Mg, and 0.10 f o r Na. D.4 S t a t i s t i c s Data were a n a l y z e d u s i n g the MINITAB s t a t i s t i c a l package (Ryan e t a l . 1981). D.5 Computing Data a n a l y s i s and word p r o c e s s i n g were done a t the B i o s c i e n c e s Data C e n t e r , U.B.C. on a VAX -11/750 r u n n i n g B e r k e l e y UNIX 4.2. T h i s t h e s i s was produced u s i n g FMT t e x t f o r m a t t i n g s o f t w a r e . B e r n a r d , D a v i d P . and M . C . F e l l e r . 1 9 8 2 . P r e c i p i t a t i o n C h e m i s t r y i n B r i t i s h C o l u m b i a : A R e v i e w . P a p e r p r e s e n t e d a t S y m p . o n A c i d i c P r e c i p -i t a t i o n and D e p o s i t i o n : A W e s t e r n P e r s p e c t i v e . J u n e 2 4 - 2 6 . B e l l i n g h a m , WA. B e r n a r d , D a v i d P . 1 9 8 1 . A c i d P r e c i p i t a t i o n i n B r i t i s h C o l u m b i a . P r e s e n t e d t o H o u s e o f Commons S u b c o m m i t t e e o n A c i d R a i n . F e b r u a r y 1 6 . C a l g a r y , A l b e r t a . 1 9 7 9 . P r i m e F a r m l a n d D i s t u r b a n c e f r o m C o a l S u r f a c e M i n i n g i n t h e C o r n B e l t , 1 9 8 0 - 2 0 0 0 . A r g o n n e N a t i o n a l L a b o r a t o r y , A r g o n n e , I I . A N L / E S - 7 0 . 50 p . . 1 9 7 9 . T h e n e e d f o r c o m p r e h e n s i v e a q u a t i c i m p a c t a n a l y s e s : The N o r t h C e n t r a l U n i t e d S t a t e s - - M i s s i s s i p p i R i v e r t r a c e m e t a l c a s e s t u d y . In M . K . W a l i ( e d . ) . E c o l o g y a n d C o a l R e s o u r c e D e v e l o p m e n t . V o l . 1 P e r g a m o n P r e s s , New Y o r k . p p . 3 7 8 - 3 8 5 . . 1 9 7 9 . P r o j e c t e d a c r e a g e o f p r i m e f a r m l a n d t o b e d i s t u r b e d by c o a l s u r f a c e m i n i n g i n t h e C o r n B e l t , 1 9 8 0 - 2 0 0 0 . i_n P r o c . P r i m e F a r m -l a n d s R e c l a m a t i o n W o r k s h o p , I n d i a n a p o l i s , I n . M a r c h 1 5 - 1 6 , 1 9 7 9 . P u r d u e U n i v . S c h o o l E n g i n e e r i n g a n d T e c h n o l o g y , I n d i a n a p o l i s , p p . 1 3 5 - 1 4 1 . . 1 9 7 8 . R e l e a s e o f s e l e c t e d t r a c e m e t a l s i n t o a q u a t i c e c o s y s -t e m s . J j _ _ A . J . D v o r a k e t a ! . An I n t e g r a t e d A s s e s s m e n t o f I n c r e a s e d C o a l U s e i n t h e C e n t r a l R e g i o n o f t h e U n i t e d S t a t e s . A r g o n n e N a t i o n a l L a b o r a -t o r y , A r g o n n e , I I . A N L / A A - 1 5 p p . 4-1 t o 4 - 2 0 . B e r n a r d , D a v i d P . i n t e r a l i o s . 1 9 7 8 . R e g i o n a l E n e r g y - E n v i r o n m e n t D a t a B o o k : M i d w e s t R e g i o n . A r g o n n e N a t i o n a l L a b o r a t o r y , A r g o n n e , I I . A N L / E E S - T M - 2 5 8 4 4 p . . 1 9 7 4 . B i o a s s a y o f f o u r f o r m u l a t i o n s o f t h e m o s q u i t o l a r v i c i d e D u r s b a n ® i n A l b e r t a s l o u g h s . C i t y o f E d m o n t o n , E n v i r o . S e r v . S e c t i E d m o n t o n , A l b e r t a . 

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