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Factors regulating the reproductive cycles of some West Coast invertebrates Himmelman, John H. 1976

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FACTORS REGULATING THE REPRODUCTIVE CYCLES OF SOME UEST COAST INVERTEBRATES by John H. Himmelman B.Sc, Acadia University, 1967 M.Sc, Memorial University of Newfoundland, 1969 A t h e s i s s u b m i t t e d i n p a r t i a l f u l f i l l m e n t of the r e q u i r e m e n t s f o r t h e degree o f DOCTOB OF PHILOSOPHY i n t h e Department c f Zoology We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA June 1976 (<T) John H. Himmelman, 1976 In present ing th is thes is in pa r t i a l fu l f i lment o f the requirements for an advanced degree at the Univers i ty of B r i t i s h Columbia, I agree that the L ibrary sha l l make it f ree ly ava i l ab le for reference and study. I fur ther agree that permission for extensive copying of th is thesis for s c h o l a r l y purposes may be granted by the Head of my Department or by h is representa t ives . It is understood that copying or pub l i ca t ion of th is thes is fo r f i n a n c i a l gain sha l l not be allowed without my wr i t ten permiss ion. Zoology-Department of The Un ivers i ty of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 July 9, 1976 Date i i ABSTRACT Annual r e p r o d u c t i v e c y c l e s a r e found i n many marine i n v e r t e b r a t e s . There i s a v a s t l i t e r a t u r e on the s u b j e c t , but the mechanisms i n v o l v e d have seldom been demonstrated. I n t h e p r e s e n t s t u d y , 8 s p e c i e s o f c h i t o n s and one sea u r c h i n were s t u d i e d f o r 3-5 y e a r s i n s o u t h w e s t e r n B r i t i s h C o l u m b i a , a t Vancouver and P o r t e a u i n the S t r a i t o f G e o r g i a e s t u a r y , and a t B o t a n i c a l Beach on the o u t e r c o a s t o f Vancouver I s l a n d . R e p r o d u c t i v e c o n d i t i o n was a s s e s s e d mainly by the gona d a l index method (percentage gonadal w e i g h t ) . There was a d i s t i n c t a nnual c y c l e i n the mean gonadal i n d e x of the u r c h i n , S t r o n g y l o c e n t r o t -us d r o e b a c h i e n s i s M i i l l e r , and t h e c h i t o n s , T o n i c e l l a l i n e a t a Wood, T o n i c e l l a i n s i g n i s Reeve, M o g a l i a h i n d s i i Reeve, Mo£alia l a e v i o r P i l s b r y , M o g a l i a c i l i a t a Sowerby, and K a t h a r i n a t u n i c a t a Wood. In S. d r o e b a c h i e n s i s , T. l i n e a t a , T. i n s i g n i s , M. l a e v i o r , and M. c i l i a t a an ab r u p t spawning o c c u r r e d i n t h e s p r i n g , u s u a l l y i n A p r i l , and i n M. h i n d s i i t h e r e was u s u a l l y an e a r l i e r spawning. K. t u n i c a t a sometimes spawned i n A p r i l but the main spawning p e r i o d was June. I n M. l a e v i o r , K. t u n i c a t a , and pr o b a b l y M. h i n d s i i , t h e gonads remained s m a l l d u r i n g the summer and r a p i d gonadal growth o c c u r r e d i n t h e autumn and w i n t e r . I n c o n t r a s t , i n S. d r o e b a c h i e n s i s , T. l i n e a t a , T, i n s i g n i s , and !• S i l i a t a g o n a d a l growth s t a r t e d s h o r t l y a f t e r spawning. The data on r e p r o d u c t i o n i n M o g a l i a ii9.H2§§ Gould were l e s s c l e a r . Mature a n i m a l s were found i n s e v e r a l seasons and drops i n t h e mean gonadal i n d e x o c c u r r e d i n l a t e w i n t e r - s p r i n g as w e l l as i n the summer. In Mo£alia l u s c o s a Gould a n i m a l s i n r i p e and spent c o n d i t i o n were found throughout the yea r . C o n s i d e r a t i o n was g i v e n t o the p o s s i b l e f a c t o r s c o n t r o l l i n g g o n a d a l growth. I n a number o f s p e c i e s , p a r t i c u l a r l y s p e c i e s of warm water o r i g i n , i t has been c l e a r l y demonstrated t h a t gonadal development i n the s p r i n g and summer i s s t i m u l a t e d by i n c r e a s e d t e m p e r a t u r e s . I f temperature a f f e c t s g onadal development i n t h e s p e c i e s i n the p r e s e n t s t u d y , i t must a c t i n s e v e r a l ways, s i n c e g o n a d a l growth o c c u r s through 2-3 p e r i o d s o f s t e a d i l y i n c r e a s i n g o r d e c r e a s i n g t e m p e r a t u r e . The i n i t i a t i o n o f g o n a d a l growth i n K. t u n i c a t a and T. l i n e a t a i n C a l i f o r n i a and Oregon o c c u r r e d a t the same time as i n t h e p r e s e n t s t u d y , a l t h o u g h t e m p e r a t u r e s i n t h e s o u t h e r n l o c a l i t i e s were f l u c t u a t i n g due t o u p w e l l i n g , i n c o n t r a s t t o the r e g u l a r t emperature changes which o c c u r r e d i n B r i t i s h Columbia. T h i s would suggest t h a t t e m p e r a t u r e was not i m p o r t a n t , a t l e a s t d u r i n g the e a r l y s t a g e s of gonadal growth i n K. t u n i c a t a and T. l i n e a t a . There a r e d i s t i n c t annual p h o t o p e r i o d changes throughout t h e g e o g r a p h i c a l ranges o f the s p e c i e s i n t h e p r e s e n t s t u d y , and i n S. d r o e b a c h i e n s i s , 1.' l i n e a t a , T. i n s i g n i s , and M. c i l i a t a most gon a d a l growth o c c u r r e d d u r i n g t h e p e r i o d of d e c r e a s i n g day l e n g t h . Food c o n d i t i o n s are known to a f f e c t t h e number o f gametes produced i n a number o f s p e c i e s , i n c l u d i n g S. d r o e b a c h i e n s i s and K. t u n i c a t a , but t h e r e i s no e v i d e n c e t h a t the t i m i n g of gonadal growth i n the s p e c i e s i n my s t u d y i s c o n t r o l l e d by a change i n fo o d c o n d i t i o n s . i i i The importance o f temperature i n s t i m u l a t i n g spawning has been s t r e s s e d by many a u t h o r s , but I know of no i n s t a n c e where i t has been demonstrated t h a t a temperature change, s u f f i c i e n t t o i nduce a n i m a l s to spawn i n the l a b o r a t o r y , a c t u a l l y o c c u r r e d at the time of n a t u r a l spawning. At F i r s t Narrows, t h e r e was u s u a l l y a major spawning when the temperature reached 7-8 °C i n the s p r i n g . However, i n 1971, S. d r o e b a c h i e n s i s spawned when the temperature was about 6.3 °C» and temperature d i f f e r e n c e s would not account f o r an a b r u p t spawning i n 1973 I n : P e r s p e c t i v e s i n Marine B i o l o g y , A. A. B u z z a t i - T r a v e r s o ( E d . ) , U n i v e r s i t y of C a l i f o r n i a P r e s s , B e r k e l e y , pp. 67-36. Compared to the pr o l o n g e d spawning i n 1974. At P o r t e a u , water t e m p e r a t u r e s showed a slow r i s e of o n l y 0.8 °C d u r i n g a two week p e r i o d i n which t h e r e was a complete spawning i n To n i c e 11a l i n e a t a , T o n i c e l l a i n sign, i s , and Hop_alia l a e v i o r . At B o t a n i c a l Beach, t e m p e r a t u r e s were a few °C warmer than a t F i r s t Narrows when T. l i n e a t a , 3. d r o e D a c h i e n -s i s , and H. h i n d s i i spawned, and the te m p e r a t u r e a t t h e time of spawning of T. l i n e a t a and K. t u n i c a t a v a r i e d s e v e r a l °C i n d i f f e r e n t y e a r s . These o b s e r v a t i o n s suggest t h a t spawning d i d not o c c u r i n response t o a p h y s i o l o g i c a l t h r e s h o l d t e m p e r a t u r e , or t o a sudden change i n te m p e r a t u r e . In 1973, S. d r o e b a c h i e n s i s and T. l i n e a t a were c o l l e c t e d a t F i r s t Narrows i n l a t e March, p r i o r t o spawning, and m a i n t a i n e d under v a r i o u s t e m p e r a t u r e and l i g h t c o n d i t i o n s : at 5.5 and 14 °C i n d a r k n e s s , and a t 5.5 and 14 °C i n l i g h t c o n d i t i o n s s i m i l a r t o thos e i n t h e f i e l d . These a n i m a l s d i d not spawn whan spawning o c c u r r e d i n t h e f i e l d . S i m i l a r l y , S. d r c j s b a c h i e n s i s , T. l i n e a t a , and T. i n s i g [ n i s c o l l e c t e d p r i o r t o spawning i n 1974 and m a i n t a i n e d i n t h e l a b o r a t o r y d i d not spawn. However, a n i m a l s r e t u r n e d t o the f i e l d from the l a b o r a t o r y d i d spawn. T h i s suggested t h a t some c o n d i t i o n i n t h e f i e l d , which was not pr e s e n t i n the l a b o r a t o r y , s t i m u l a t e d spawning, and t n i s f a c t o r d i d not appear t o be l i g h t or temperature. An a b r u p t spawning a t F i r s t Narrows and P o r t e a u i n 1973 o c c u r r e d a t t h e time of the s p r i n g p h y t o p l a n k t o n o u t b u r s t , but i n 1974 spawning a t F i r s t Narrows was l e s s a b r u p t c o r r e s p o n d i n g t o the s l o w development o f the p h y t o p l a n k t o n bloom i n t h a t year. In t he l a b o r a t o r y , a l a r g e p r o p o r t i o n of S. d r o e b a c h i e n s i s , !• a n d T. i n s i a n i s spawned when they were exposed to n a t u r a l p h y t o p l a n k t o n c o l l e c t e d d u r i n g t h e bloom w i t h a 50 u mesh n e t . T h i s suggested t h a t some s u b s t a n c e bound t o or r e l e a s e d by p h y t o p l a n k t o n s t i m u l a t e d spawning. For s p e c i e s w i t h p l a n k t o t r o p h i c l a r v a e the s y n c h r o n i z a t i o n o f spawaing w i t h the p h y t o p l a n k t o n bloom i n c r e a s e s the p r o b a b i l i t y o f b o t a f a v o u r a b l e fo o d and temperature c o n d i t i o n s f o r development or eggs, l a r v a e , and j u v e n i l e s . Gonadal growth d u r i n g the c o l d e s t p a r t o f the year and spawning a t the time o f the s p r i n g p h y t o p l a n k t o n uloom was found i n S. d r o e b a c h i e n s i s , T. l i n e a t a , T. i n s i g n i s , M. c i i i a t a , and probanly K. t u n i c a t a. T h i s p a t t e r n i s c h a r a c t e r i s t i c * o f marine i n v e r t e b r a t e s w i t h p e l a g i c l a r v a e l i v i n g i n c o l d waters. i v TABLE OF CONTENTS INTRODUCTION ... .............. 1 S T U D Y -&JKJEAS •*•«•••• • ^ •••*:••••••••••#••''•»••* y * • 6 RESULTS R e l a t i o n of Gonad S i z e t o Animal S i z e ................. 17 R e p r o d u c t i v e c y c l e s K a t h a r i n a t u n i c a t a ........,...... ................ 27 Mojgalia h i n d s i i 32 M o p a l i a c i l i a t a .................................. , 35 M o g a l i a l i a n o s a 38 MO£aiia l a e v i o r .................................. 40 M o p a l i a muscosa 43 T o n i c e l l a l i n e a t a 46 22si£sii§ issiasis 51 Strong;y.iocentrotus d r o e b a c h i e n s i s ................ 54 O b s e r v a t i o n s and Experiments on Spawning Temperature and Spawning i n t h e F i e l d ............. 59 E f f e c t o f L i g h t and Temperature on spawning i n the L a b o r a t o r y 67 P h y t o p l a n k t o n O b s e r v a t i o n s i n t h e F i e l d 74 E x p e r i m e n t s on the E f f e c t of P h y t o p l a n k t o n on Spci%rni.ii•••*••••••••••••••«•**•*«••••••••'•*•• 3 .2 V DISCUSSION The JBegulation o f R e p r o d u c t i v e C y c l e s , .. . . . 86 p o s s i b l e f a c t o r s R e g u l a t i n g Gonadal Growth ............ 87 Temperature ...................................... 89 P h o t o p e r i o d ....................................... , 92 N u t r i t i o n ........................................ 95 P o s s i b l e F a c t o r s R e g u l a t i n g Spawning ..................101 Temperature .........,,.,....,*.*. ,•...... 102 l i g h t 110 Chemical F a c t o r s ................................. 110 P h y t o p l a n k t o n 112 I n t e r n a l C o n s i d e r a t i o n s ............................... 118 E v o l u t i o n a r y and Geographic C o n s i d e r a t i o n s ............. 121 fiEFERENCES ................................................. 127 v i TABLES Ta b l e I , L i v e weight (g) o f a n i m a l s a t s e x u a l m a t u r i t y , and weight range c o l l e c t e d f o r t h e study of t h e r e p r o d u c t i v e c y c l e , f o r each of t h e s p e c i e s i n t h e p r e s e n t s t u d y . ......,y, ............................ 26 Ta b l e I I . D e n s i t y ( m i l l i o n s o f c e l l s / m 3 ) o f common s p e c i e s o f p h y t o p l a n k t o n a t S t a t i o n s 1, 2 and 6 b e f o r e and d u r i n g t h e bloom i n 1973. (Dr John S t o c k n e r , p e r s . comm.) 77 T a b l e ' I I I . , D e n s i t y ( m i l l i o n s o f c e l i s / m 3 ) of T h a l a s s i -sp. and Skeletonema costatum a t S t a t i o n s 1 and 2 from 6 t h March t o 3 r d May 1974 (Dr John S t o c k n e r , T a b l e IV. D e n s i t y ( m i l l i o n s ox c e l l s / m 3 ) o f diatoms a t S t a t i o n s A and B i n t h e S t r a i t o f G e o r g i a , and f o r S t a t i o n C i n Juan de Fuca S t r a i t , d u r i n g w i n t e r and s p r i n g 1973 (Mr J a e Shim, p e r s . , comm.),....,.....,...,. . 79 Tab l e V,, D e n s i t y ( m i l l i o n s o f c e l l s / m 3 ) of diatom s p e c i e s a t S t a t i o n s A, B, and C b e f o r e and d u r i n g the bloom i n 1973 (Mr Jae Shim, p e r s . comm.) .,.,.............. ..., . 80 Tab l e V I . , E f f e c t of n a t u r a l p h y t o p l a n k t o n and sperm s u s p e n s i o n on St r ong v.1ocentr o t us d r o e b a c h i e n s i s , T o n i c e l l a l i n e a t a , and T o n i c e l l a i n s i g n i s . ; ............ 84 Table V I I . , R e p o r t e d d e v e l o p m e n t a l t i m e s under v a r i o u s t e m p e r a t u r e s f o r t h e s p e c i e s i n t h e p r e s e n t s t u d y . .... 108 v i i FIGURES F i g . 1.. Southwestern. B r i t i s h C o lumbia, showing where t h e s t u d i e s o f r e p r o d u c t i v e c y c l e s were made and where e n v i r o n m e n t a l d a t a were c o l l e c t e d . ...... .............. . 7 F i g . 2 A—H, R e l a t i o n between the gonadal i n d e x p e r c e n t a g e v a l u e ( a r c s i n v a l u e s ) and the t o t a l l i v e a n i m a l weight f o r (A) K a t h a r i n a t u n i c a t a , (B) M o g a l i a h i n d s i i , (C) Mop a l i a .. c i l i a t a , (D) M o g a l i a I i g n o s a , (E) Mo £ a l i a l a e v i o r , (F) T o n i c e l l a l i n e a t a , (G) T o n i c e l l a i n s i g n i s , and (H) S t r o n g ^ l o c e n t r o t u s d r o e b a c h i e n s i s , u s i n g a n i m a l s c o l l e c t e d p r i o r t o t h e spawning p e r i o d . . „ 18 F i g . 3. Mean gona d a l i n d e x and 95% c o n f i d e n c e l i m i t s f o r K a t h a r i n a t u n i c a t a a t B o t a n i c a l Beach and P o i n t No P o i n t . The number a s s o c i a t e d w i t h each bar i n t h i s and th e f o l l o w i n g f i g u r e s of gonadal i n d e x c y c l e s i s t h e sample s i z e . 28 F i g . , 4 . Summary of spawning o b s e r v a t i o n s on Katha_rifia- t u n -i c a t a . 29 F i g , 5.,Mean gona d a l i n d e x and 95% c o n f i d e n c e l i m i t s f o r M o g a l i a h i n d s i i a t B o t a n i c a l Beach and F i r s t Narrows.,. 33 F i g , 6. Summary o f spawning o b s e r v a t i o n s on S o g a l i a h i n d s i i ; symbols d e f i n e d i n F i g u r e 4, , 33 F i g . 7. Mean gonadal i n d e x and 95% c o n f i d e n c e l i m i t s f o r M o g a l i a c i l i a t a a t F i r s t Narrows and B o t a n i c a l Beach. . 36 F i g , 8., Summary o f spawning o b s e r v a t i o n s on. M o g a l i a c i l i a t a : symbols d e f i n e d i n F i g u r e 4, ......,,,., ,,,,, . 36 F i g . 9. Mean gonadal i n d e x and 95% c o n f i d e n c e l i m i t s f o r flogalia i i g n o s a a t P o r t e a u , and mean gonadal i n d e x and gonad a l i n d i c e s of each a n i m a l c o l l e c t e d a t F i r s t Narrows. ,. ....................,'..,, ,,y...... ., 39 F i g . , 10. , Summary o f spawning o b s e r v a t i o n s on Mojgalia I i g n o s a ; symbols d e f i n e d i n F i g u r e 4. 39 F i g , 11.. Mean gonadal i n d e x and 95% c o n f i d e n c e l i m i t s f o r M o g a l i a l a e v i o r a t P o r t e a u and F i r s t Narrows. ...,..... 41 F i g . 12., Summary o f spawning o b s e r v a t i o n s on MogaJLia l a e v i o r ; symbols d e f i n e d i n F i g u r e 4 41 F i g . 13. Gonadal i n d i c e s o f each i n d i v i d u a l o f M o g a l i a museosa c o l l e c t e d ar B o t a n i c a l Beach. ..............,... 44 F i g , 14, Summary o f spawning o b s e r v a t i o n s on M o g a l i a v i i i muscosa; symbols d e f i n e d i n F i g u r e 4. ................. 45 F i g . 15. .. Mean gonadal i n d e x and 95% c o n f i d e n c e l i m i t s f o r T o n i c e l l a l i n e a t a a t B o t a n i c a l Beach, F i r s t Narrows and P o r t e a u . 47 F i g . 16., Summary o f spawning o b s e r v a t i o n s on T o n i g e l l a l i n e a t a ; symbols d e f i n e d i n F i g u r e 4. v . , 48 F i g . 17. Mean gon a d a l i n d e x and 95% c o n f i d e n c e l i m i t s f o r T o n i c e l l a . i n s i g n i s a t F i r s t Narrows and P o r t e a u . , . . , . , . , 52 F i g . 18. Summary of spawning o b s e r v a t i o n s on T o n i c e l l a i n s i g n i s ; symbols d e f i n e d i n F i g u r e 4.,.,,...,,,,«,,,,. 52 F i g . 19.,Mean gon a d a l i n d e x and 95% c o n f i d e n c e l i m i t s f o r §irongxlocentrotus d r o e b a c h i e n s i s a t F i r s t Narrows and B o t a n i c a l Beach, and f o r S t r o n g y l o c e n t r o t u s fiurjauratus a t B o t a n i c a l Beach. .................................... 55 F i g , 20. Summary of spawning o b s e r v a t i o n s on S t r o n g y l o c e n -t r o t u s d r g e b a c h i e n s i s ; symbols d e f i n e d i n F i g u r e 4.,,,, 56 F i g . 21. Mean s e a water t e m p e r a t u r e (± s t a n d a r d d e v i a t i o n ) f o r the f i r s t h a l f and second h a l f o f each month d u r i n g March 1971—September 1974 a t F i r s t Narrows compared t o t h e f o u r y e a r mean (1971-1974) f o r t h e f i r s t h a l f and l a s t h a l f of each month; mean g o n a d a l i n d e x v a l u e s f o r S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s , T o n i c e l l a i i f i e a t a * T o n i c e l l a i a S i a i l A J i / USEJlAAii l a e v i o r . Mo£alia c i l i a t a , Mo£alia h i n d s i i , . a n d M o g a l i a l i g n o s a superimposed on t h e s e d a t a , show t h e r e l a t i o n s h i p o f t h e s e c y c l e s t o t e m p e r a t u r e . . 60 F i g . 22. A comparison o f t h e mean gonadal i n d e x c y c l e s f o r T o n i c e l l a l i n e a t a , T o n i c e l l a i n s i g n i s , M o j j a l i a l a e v i o r and Mo£alia l i g n o s a a t P o r t e a u d u r i n g A p r i l 1 9 7 1 — A p r i l 1 9,73• . * • * • • -# • • • • • «• • • • * • • * •* • • • •-»»-*•'*•• •» • • ••,-*»••;•"•;'•/»".* • . 6 i F i g , . 23. Mean sea water t e m p e r a t u r e (± s t a n d a r d d e v i a t i o n ) f o r each month a t A m p h i t r i t e P o i n t and Saerringham P o i n t d u r i n g the p e r i o d May 1970-July 1974 compared t o the f i v e y e a r monthly mean t e m p e r a t u r e (1970—1974) f o r each l o c a t i o n ; mean gonadal i n d i c e s o f K a t h a r l n a t u n -i c a t a , T o n i c e l l a l i n e a t a , MO£aiia h i n d s i i , Mo£alia c i l i a t a , S t r o n g y l o c e n t r o t u s d r o e j o a c h i e n s i s - and S t r o n g y l o c e n t r o t u s £ur£uratus superimposed on t h e s e d a t a show t h e r e l a t i o n s h i p o f t h e c y c l e s t o F i g . 24., Mean gon a d a l i n d e x and 95% c o n f i d e n c e l i m i t s f o r S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s a t F i r s t Narrows d u r i n g March-May 1973, f o r groups of a n i m a l s t r a n s f e r r e d t o f o u r l i g h t and t e m p e r a t u r e r e g i m e s i n the l a b o r a t o r y , and f o r one group wnich was i x t r a n s f e r r e d t o F i r s t Narrows on 19th A p r i l ; DH (dark—warm), DC ( d a r k — c o l d , 1» (light—warm) and LC ( l i g h t - c o l d ) a r e l a b o r a t o r y c o n d i t i o n s d e s c r i b e d i n til© t © xii * ./ • • * • • • • * *» • * # • • »• •» • •.•*'-•>• •••»••#,• *••#•• #'*#•••»*'.;.' 63 F i g . 25. Mean gonadal i n d e x and 95% c o n f i d e n c e l i m i t s f o r S ^ o n g j ; l o c e n t r o t a s d r o e b a c h i e n s i s a t F i r s t Narrows from March—September 1974, and f o r groups t r a n s f e r r e d t o v a r i o u s t emperature regimes i n t h e l a b o r a t o r y . , . , . . , 69 F i g , 26. Mean gonadal i n d e x and 95% c o n f i d e n c e l i m i t s f o r !2ai£®Aia l i n e a t a a t F i r s t Narrows from March—May 1973, and f o r groups t r a n s f e r r e d t o v a r i o u s l i g h t and temperature regimes i n t h e l a b o r a t o r y . . . . . . . . . . . . . . . . . , 71 F i g . 27, Mean gonadal i n d e x and 95% c o n f i d e n c e l i m i t s f o r T o n i c e l l a l i n e a t a a t F i r s t Narrows d u r i n g March-September 1974, and f o r groups p l a c e d i n v a r i o u s t e m p e r a t u r e regimes i n t h e l a b o r a t o r y , and f o r one group t r a n s f e r r e d t o F i r s t Narrows on 15th A p r i l . ..... 72 F i g . , 2 8 . P h y t o p l a n k t o n abundance as measured by c h l o r o p h y l l a f o r s i x s t a t i o n s i n Howe Sound and one i n I n d i a n Arm d u r i n g F e b r u a r y — J u n e 1973 (Dr John S t o c k n e r , p e r s . comm.): each v a l u e i s t h e mean of f i v e measurements made a t 0-5 m; mean gonadal ind e x v a l u e s f o r S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s , Tonice11a l i n e a t a , and T o n i e e l l a i n s i g n i s , superimposed on t h e s e d a t a , show the synchrony o f spawning w i t h the p h y t o p l a n k t o n bloom i n 1973. . . 75 F i g . , 2 9 . P h y t o p l a n k t o n abundance measured by c h l o r o p h y l l a f o r S t a t i o n s i n the v i c i n i t y o f f i r s t Narrows d u r i n g F e b r u a r y — J u n e 1974: v a l u e s f o r S t a t i o n s 1, 2 and 11 r e p r e s e n t t h e mean of t h r e e measurements from 1—5 m (Dr John S t o c k n e r , p e r s . comm.) and v a l u e s f o r F i r s t Narrows and J e r i c h o Beach are s i n g l e measurements t a k e n near the s u r f a c e : mean gonadal i n d i c e s f o r S t r o j i g ^ l o c e n t r o t u s d r o e b a c h i e n s i s , T o n i c e l l a l i n e a t a , and T o n i c e l l a i n s i g n i s , superimposed on the s e d a t a , show the p r o l o n g e d spawning p e r i o d c o r r e s p o n d i n g t o th e d e l a y e d and slow growth o f p h y t o p l a n k t o n i n 1974. . 76 F i g . 30. Mean gonadal i n d e x and 95% c o n f i d e n c e l i m i t s f o r groups o f S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s and T o n i c e l l a l i n e a t a t r e a t e d w i t h p h y t o p l a n k t o n from 21-27th A p r i l 1973, compared w i t h e v e n t s i n t a n k s from which t h e s e groups s e r e t a k e n . . . . . . . . . . . . . . . . . . . . . . . . . . 84 X ACKNOWLEDGEMENTS I w i s h t o thank John S t o c k n e r , Dave C l i f f and Karen Monroe, a t the P a c i f i c E n v i r o n m e n t a l I n s t i t u t e , Vancouver, f o r a l l o w i n g me t o use t h e i r data on p h y t o p l a n k t o n abundance and p h y s i c a l c o n d i t i o n s ; and Jae Shim, I n s t i t u t e of Oceanography, U.B.C., f o r p r o v i d i n g me w i t h i n f o r m a t i o n on t h e diatom blooms a t Juan de Fuca S t r a i t and t h e S t r a i t o f G e o r g i a . Without t h i s i n f o r m a t i o n t h e c o n c l u s i o n s o f t h i s paper would be p o o r l y s u p p o r t e d . Dr Thomas H. C a r e f o o t , my g r a d u a t e s u p e r v i s o r , made d e t a i l e d c r i t i c i s m s o f s e v e r a l d r a f t s o f t h i s m a n u s c r i p t , and o f an e a r l i e r paper. . C a r e f u l c o n s i d e r a t i o n o f t h i s t h e s i s was a l s o g i v e n by my g r a d u a t e committee, Drs Ian McTaggart Cowan, G i l b e r t Hughes and John P h i l l i p s , as w e l l as by t h e e x t e r n a l e x a m i n e r s , Drs J e f f e r s o n Gonor and John Lawrence. Dr Cowan a l s o h e l p e d me w i t h the i d e n t i f i c a t i o n o f the M o p a l i a s p e c i e s , , I am g r a t e f u l to my w i f e , Helga G u d e r l e y , f o r her encouragement t h r o u g h o u t t h i s s t u d y , f o r h e l p i n c o l l e c t i n g a n i m a l s , and f o r f r e q u e n t a d v i c e on the p r e s e n t a t i o n of i n f o r m a t i o n i n t h e t h e s i s . D u r i n g t h e p h y t o p l a n k t o n e x p e r i m e n t s , some l a b o r a t o r y f a c i l i t i e s were p r o v i d e d by Dr Max T a y l o r , and Rosemary Waters gave me t e c h n i c a l a s s i s t a n c e . I had many v a l u a b l e d i s c u s s i o n s w i t h P a u l F a l k o w s k i . on the p o s s i b l e r e l a t i o n s h i p s between p h y t o p l a n k t o n and spawning. Dr Norman Wilomovsky was generous i n making the f a c i l i t i e s a t B o t a n i c a l Beach a v a i l a b l e t o me. The f i r s t few y e a r s of the B o t a n i c a l Beach e x p e r i e n c e were s h a r e d w i t h P a u l B r e e n , Hong Woo Koo and S t e v e H e i z e r . D o l o r e s L a u r i e n t e and Steve.Borden f r e g u e n t l y h e l p e d me w i t h t h e use o f t h e computer f a c i l i t i e s a t O.B.C. I w i l l always remember the encouragement and a s s i s t a n c e of my f r i e n d s , e s p e c i a l l y George L i l l y , P e t e r Newroth, Barbara Moon, Randy Kaneen, Frank Boas, R i c k B e c k w i t t , Fred M c C o n n e l l , Joanne D r u e h l , Tom Munford, P e t e r Hochachka, Jeremy F i e l d s , B r i a n Murphy, Ed Buskey and Jim Markham, D e d i c a t e d t o 762 K a t h a r i n a t u n i c a t a 292 M o g a l i a h i n d s i i 205 M o g a l i a c i l i a t a 116 M o g a l i a I i g n o s a 3 35 M o g a l i a l a e v i o r 146 M o g a l i a guscosa 1176 T o n i c e l l a l i n e a t a 373 T o n i c e l l a i n s i g n i s and 940 S t r o n g y . l o c e n t r o t u s d r o e b a c h i e n s i s which were s a c r i f i c e d d u r i n g the c o u r s e o f t h i s s t u d y . 1 INTRODUCTION R e p r o d u c t i v e c y c l e s . i n v o l v e t h e p e r i o d i c growth and development of gonads, f o l l o w e d by t h e u s u a l l y a b r u p t r e l e a s e of gametes. I n the m a j o r i t y o f marine i n v e r t e b r a t e s they f o l l o w annual p a t t e r n s , T h i s i s p a r t i c u l a r l y t r u e o f s h a l l o w water s p e c i e s i n temperate s e a s , where e n v i r o n m e n t a l c o n d i t i o n s show d i s t i n c t a n n u a l f l u c t u a t i o n s , but a n n u a l r e p r o d u c t i v e c y c l e s a r e a l s o found i n some s p e c i e s i n the t r o p i c s and i n deep s e a s , where c o n d i t i o n s are n e a r l y c o n s t a n t . There has been much study C D r e p r o d u c t i o n i n marine i n v e r t e b r a t e s , and t h e s u b j e c t has been t h o r o u g h l y r e v i e w e d by G i e s e . and Pe a r s e . (1974), Many workers c o r r e l a t e d t h e v a r i o u s phases o f g o n a d a l development and spawning w i t h e n v i r o n m e n t a l f a c t o r s , p a r t i c u l a r l y w i t h t e m p e r a t u r e . E a r l y i n t h i s c e n t u r y , A p p e l l o f (1912) c o n c l u d e d , from o b s e r v a t i o n s of the n o r t h e r n h o l o t h u r o i d , Cucumaria f r o n d o s a , t h a t t e m p e r a t u r e was i m p o r t a n t f o r two phases of t h e r e p r o d u c t i v e p r o c e s s : (1) t h e development o f t h e gonads, and (2) the d e v e l o p m e n t a l s t a g e s a f t e r f e r t i l i z a t i o n . The l a t t e r was c o n f i r m e d f o r a v a r i e t y o f s p e c i e s by Runnstrom (1927a). , He found t h a t t h e tem p e r a t u r e t o l e r a n c e s of p e l a g i c l a r v a e were c l o s e l y r e l a t e d t o t h e te m p e r a t u r e s a t the time, of spawning and t o g e o g r a p h i c a l d i s t r i b u t i o n . , O r t o n (1920) c o r r e l a t e d b r e e d i n g time w i t h t emperature f o r a number o f European s p e c i e s , and c o n c l u d e d t h a t most a n i m a l s b r e e d a t a d e f i n i t e t e m p e r a t u r e which i s a p h y s i o l o g i c a l c o n s t a n t f o r each s p e c i e s . He i m p l i e d \ 2 t h a t a c e r t a i n t e m p e r a t u r e change o r merely r e a c h i n g a c r i t i c a l t e m p e r a t u r e l e v e l s t i m u l a t e d spawning. Many a u t h o r s have a c c e p t e d O r t o n ' s i d e a s . I t has been demonstrated f o r a number of s p e c i e s t h a t i n c r e a s e d t emperature s t i m u l a t e s g o n a d a l development (eg. L o o s a n o f f & D a v i s , 1963). However, t h e i m p o r t a n c e of t e m p e r a t u r e i n t h e g o n a d a l development of o t h e r s p e c i e s , and f o r spawning i n g e n e r a l , i s not c l e a r , , O r t o n * s c o n c l u s i o n s were t o o f a r r e a c h i n g ( K o r r i n g a , 1957). The i n f l u e n c e of o t h e r e n v i r o n m e n t a l f a c t o r s has a l s o been s t u d i e d . Some r e s e a r c h e r s have c o n s i d e r e d p h o t o p e r i o d , which i s known t o c o o r d i n a t e r e p r o d u c t i v e a c t i v i t y i n many mammals, b i r d s and i n s e c t s , but t h i s has not been c l e a r l y demonstrated f o r any marine i n v e r t e b r a t e . , Food may be r e q u i r e d f o r go n a d a l development, but t h e r e are few i n s t a n c e s where i t has been demonstrated t h a t a change i n t h e f o o d c o n d i t i o n s s t i m u l a t e s g onadal a c t i v i t y , flany o t h e r f a c t o r s , i n c l u d i n g l u n a r c y c l e s , s a l i n i t y , wave a c t i o n and c h e m i c a l s t i m u l a t i o n , have been r e l a t e d t o the t i m i n g of r e p r o d u c t i v e e v e n t s , but most of the s e c o n s i d e r a t i o n s a r e s p e c u l a t i v e and not s u p p o r t e d by e n v i r o n m e n t a l d a t a . A l t h o u g h t h e l i t e r a t u r e on r e p r o d u c t i v e c y c l e s i s e x t e n s i v e , we s t i l l do not have a good u n d e r s t a n d i n g of the p r o c e s s e s i n v o l v e d . The o b j e c t i v e of t h e p r e s e n t s t u d y was to e l u c i d a t e f u r t h e r the f a c t o r s c o n t r o l l i n g r e p r o d u c t i v e c y c l e s . The s t u d y a r e a was on the s o u t h e r n c o a s t o f B r i t i s h C o lumbia, an a r e a c h a r a c t e r i z e d by a r e g u l a r but moderate annu a l c y c l e o f e n v i r o n m e n t a l c o n d i t i o n s . E i g h t s p e c i e s o f c h i t o n s and one sea u r c h i n were examined f o r 3-5 y e a r s . Most of t h e o b s e r v a t i o n s were made i n 3 t h r e e l o c a t i o n s , two i n the S t r a i t o f G e o r g i a e s t u a r y , and one on the o u t e r c o a s t of Vancouver I s l a n d . I hoped t h a t o b s e r v a t i o n s o ver d i f f e r e n t y e a r s and p l a c e s would i n d i c a t e t h a t c e r t a i n e n v i r o n m e n t a l c o n d i t i o n s were c o n s i s t e n t l y p r e s e n t d u r i n g p a r t i c u l a r phases o f the r e p r o d u c t i v e p r o c e s s . A l s o I thought i t would be u s e f u l t o compare the r e p r o d u c t i v e p a t t e r n s i n c l o s e l y r e l a t e d and n o n - r e l a t e d s p e c i e s . The p r e s e n c e of s i m i l a r p a t t e r n s would suggest t h a t s i m i l a r e n v i r o n m e n t a l c u e s were c o n t r o l l i n g r e p r o d u c t i v e e v e n t s , and the i d e n t i f i c a t i o n of t h e s e cues i n some s p e c i e s would a i d i n e l u c i d a t i n g t h e cues i n s p e c i e s which show a s i m i l a r p a t t e r n . A l t e r n a t i v e l y , d i f f e r e n t p a t t e r n s would s u g g e s t t h a t d i f f e r e n t s t i m u l i were used t o c o o r d i n a t e r e p r o d u c t i v e a c t i v i t y . A l t h o u g h e x p e r i m e n t a l s t u d i e s are d e s i r a b l e , and e s s e n t i a l f o r t e s t i n g h y p o t h e t i c a l c u e s , t h u s f a r I have o n l y conducted e x p e r i m e n t s examining the s t i m u l u s f o r spawning. The time of spawning i s of p a r t i c u l a r i m p o r t a n c e f o r a n i m a l s w i t h p e l a g i c l a r v a e , s i n c e i t i s an a d a p t i v e n e c e s s i t y t h a t t h e l a r v a e be produced when c o n d i t i o n s a r e f a v o u r a b l e f o r t h e i r growth and development. One would e x p e c t t h a t a knowledge of t h e r e q u i r e m e n t s of the l a r v a e would be u s e f u l i n u n d e r s t a n d i n g t h e f a c t o r s c o n t r o l l i n g spawning. While the synchrony of p h y t o p l a n k t o n blooms and spawning has been r e c o g n i z e d f o r many y e a r s , and p h y t o p l a n k t o n i s of o b v i o u s i m p o r t a n c e t o p l a n k t o t r o p h i c l a r v a e (Thorson, 1946), I know of no s t u d y i n which t h e e f f e c t of p h y t o p l a n k t o n on spawning was examined e x p e r i m e n t a l l y . Presumably t h i s i s due t o p a s t emphases on t e m p e r a t u r e as a c o n t r o l l i n g f a c t o r . , I n t h e p r e s e n t s t u d y , I 4 t e s t e d both t h e e f f e c t o f tem p e r a t u r e and o f p h y t o p l a n k t o n on spawning i n t h r e e of t h e s p e c i e s s t u d i e d . , The e i g h t s p e c i e s of c h i t o n s s t u d i e d were: K a t h a r i n a - t u n -i c a t a wood, M o g a l i a h i n d s i i fieeve, M o g a l i a c i l i a t a sowerby, Mp_.ga.lia l i & n o s a G o uld, M o g a l i a l a e v i o r P i l s b r y , Mo£al.ia muscosa G o u l d , T o n i c e l l a l i n e a t a Wood and T o n i c e l l a - i n s i g n i s • R e e v e . A l l are common i n t e r t i d a l and/or s u b t i d a l s p e c i e s on t h e west c o a s t of N o r t h America. Only K. ..tunicata e x t e n d s beyond t h i s a r e a t o A s i a t i c s h o r e s , I n C a l i f o r n i a , r e p r o d u c t i o n i n K. t u a i e a t a has been s t u d i e d e x t e n s i v e l y and some r e p r o d u c t i v e s t u d i e s have a l s o been made on M. h i n d s i i , M. . c i 1 i a t a , M. I i g n o s a and M.,muscosa { B a r n a w e l l , 1954; Thorpe, 1962; G i e s e , 1969)., The g e o g r a p h i c a l ranges o f M o g a l i a l a e v i o r and T, i n s i g n i s a r e l i m i t e d p r i m a r i l y to t h e B r i t i s h Columbia and Washington c o a s t l i n e , and t h e r e a r e no p u b l i s h e d a c c o u n t s o f r e p r o d u c t i o n i n t h e s e s p e c i e s . Except f o r one study on t h e r e p r o d u c t i v e b i o l o g y of T, l i n e a t a on the Oregon c o a s t and i n Puget Sound (Barnes, 1972), the p r e s e n t s t u d y i s t h e o n l y account o f s e a s o n a l r e p r o d u c t i v e a c t i v i t y i n the above c h i t o n s i n l o c a t i o n s n o r t h o f C a l i f o r n i a and c l o s e r t o the c e n t e r o f t h e i r g e o g r a p h i c a l d i s t r i b u t i o n . I n c o n t r a s t to t h e above c h i t o n s , t h e green sea u r c h i n , S£rong^locentrot u s d r o e b a c h i e n s i s M u l l e r , has a wide g e o g r a p h i c a l d i s t r i b u t i o n and o c c u r s i n the North A t l a n t i c , A r c t i c and North P a c i f i c Oceans., I t i s a dominant member o f the s u b t i d a l community throughout much o f i t s range. ;, S u r p r i s i n g l y , i t s r e p r o d u c t i v e c y c l e has been d e s c r i b e d o n l y on t h e A t l a n t i c c o a s t o f North America (Cocanour & A l l e n , 1967; Himmelman, 5 1969). I n the p r e s e n t s t u d y b r i e f o b s e r v a t i o n s were a l s o made on the n o r t h e a s t P a c i f i c sea u r c h i n , S t r o a g i i o c e n t r o t u s fiurjDur-a t u s ( S t i m p s o n ) , p r i m a r i l y t o compare i t t o S , . d r o e b a c h i e n s i s . Both t h e c h i t o n s and u r c h i n s were e a s i l y found and c o l l e c t e d , and t h e i r gonads are d i s t i n c t and s e p a r a t e organs, t h u s making i t easy t o a s s e s s t h e i r r e l a t i v e s i z e i n d i f f e r e n t s e a s o n s . 6 STUDY. AREAS Host o f t h e f i e l d o b s e r v a t i o n s i n the p r e s e n t s t u d y were made a t t h r e e l o c a t i o n s i n B r i t i s h Columbia: a t F i r s t Narrows i n Vancouver, a t P o r t e a u i n Howe Sound, and a t B o t a n i c a l Beach on th e o u t e r c o a s t o f Vancouver I s l a n d ( f i g , 1), F i r s t Harrows and P o r t e a u , , F i r s t Narrows and P o r t e a u a r e i n t h e S t r a i t o f G e o r g i a and a r e c h a r a c t e r i z e d by marked s e a s o n a l f l u c t u a t i o n s i n temperature and s a l i n i t y , , I n June and J u l y peak r u n o f f o c c u r s from the F r a s e r R i v e r and s a l i n i t i e s drop below 20°/oo i n the upper 3 m of t h e water column. D u r i n g the remainder o f t h e year s a l i n i t i e s u s u a l l y f l u c t u a t e between 23-28°/oo i n the upper 40 m o f t h e water column and r a r e l y reach 30°/oo. At F i r s t Narrows T o n i c e l l a l i n e a t a , T o n i c e ixa. i n s i g n i s , .aogalia l a e v i o r , M o p a l i a • l i g n o s a , and S t r o n g y l o c e n t r o t u s droe-b a c h i a n s i s Mere c o l l e c t e d from depths o f 2—12 m below ML1S (mean low water s p r i n g t i d e s ) and a t P o r t e a u T o n i c e l l a l i n e a t a , T o n i c e l l a i n s i g n i s , Mo£alia l a e v i o r and Mo j> a l i a i x g n o s a were c o l l e c t e d from 3-15 m below ML8S u s i n g SCUBA. The bottom a t F i r s t Narrows i s g e n t l y s l o p i n g sandstone w i t h some a r e a s c o v e r e d by b o u l d e r s . S t r o n g t i d a l c u r r e n t s sweep a c r o s s t h i s a r e a . , At P o r t e a u t h e bottom c o n s i s t s of a s t e e p b o u l d e r t a l u s w i t h a few a r e a s o f bedrock o u t c r o p s . Diatoms and ephemeral macrophytes a r e t h e predominant v e g e t a t i o n i n both a r e a s . Pig. 1. Southwestern B r i t i s h Coluabia, showing where the studies of reproductive cycles were made and where environmental data were c o l l e c t e d . 8 B o t a n i c a l Bea.clu B o t a n i c a l Beach r e c e i v e s heavy wave a c t i o n from t h e open P a c i f i c Ocean and i t s h y d r o g r a p h i c c o n d i t i o n s a r e t y p i c a l of o u t e r c o a s t a r e a s i n B r i t i s h Columbia. S u r f a c e t e m p e r a t u r e s f l u c t u a t e from 6-12 °C a n n u a l l y and s a l i n i t i e s remain between 27—32°/oo (Green, 1 9 6 8 ) . H e r e 4 s p e c i e s o f c h i t o n s and 2 u r c h i n s from the i n t e r t i d a l r e g i o n were s t u d i e d . I l l i i a r i n a t u n i c a t a was abundant . and i n o r d e r t o reduce v a r i a b i l i t y i n gonad s i z e due t o h a b i t a t d i f f e r e n c e s , a l l c o l l e c t i o n s were made from one g e n t l y s l o p i n g bench on which the phaeophyte, HedOjghj.llum s e s s i l e , predominated. , A d u l t T o n i c e l l a i i a g a t a , M o g a l i a h i n d s i i and M o g a l i a c i l i a t a were more d i f f i c u l t t o f i n d and were c o l l e c t e d from a wide r range o f h a b i t a t s , but mos t l y from v e r t i c a l rock f a c e s and u n d e r c u t s . The above s p e c i e s were always c o l l e c t e d from 0—1.5 m above MLSS., M o g a l i a lM§cosa was c o l l e c t e d from many s c a t t e r e d p o o l s a t 1.8—3.0 m above MLWS t i d a l h e i g h t . , A number of c o l l e c t i o n s o f S t r o n a y l o -£sntrotus d r o e b a c h i e n s i s and S t r ^ n g Y l g c e n t r o t u s g u r g u r a t u s were made from 0-0.4 m above Ml US i n one a r e a on a sa n d s t o n e bench which was p r o t e c t e d from heavy wave a c t i o n by an o u t e r r i d g e of r o c k s , , There a r e mixed s e m i d i u r n a l t i d e s a t B o t a n i c a l Beach and the low i n t e r t i d a l r e g i o n i s u s u a l l y o n l y exposed d u r i n g t h e lower low t i d e , which o c c u r s i n the e a r l y morning i n t h e s p r i n g and summer and i n t h e e v e n i n g i n t h e autumn and w i n t e r . , Other c o l l e c t i n g s i t e s . . S e v e r a l c h i t o n s p e c i e s were c o l l e c t e d a t 3—9 m below MLHS on a steep r o c k f a c e a t E a g l e Harbour, 11 km o u t s i d e o f F i r s t Narrows ( F i g . 1 ) . S a l i n i t y and temperature c o n d i t i o n s here are p r o b a b l y s i m i l a r t o those a t F i r s t Narrows, but t h e r e a r e no s t r o n g t i d a l c u r r e n t s . 9 K a t h a r i n a t u n i c a t a was c o l l e c t e d i n t e r t i d a l l y a t t h r e e a d d i t i o n a l l o c a t i o n s on the west c o a s t of Vancouver I s l a n d ; a t P o i n t No P o i n t i n Juan de Fuca S t r a i t , and a t Frank I s l a n d and A m p h i t r i t e P o i n t , about 110 km northwe s t of B o t a n i c a l Beach ( F i g , 1). P o i n t No P o i n t i s somewhat p r o t e c t e d from wave a c t i o n by i t s l o c a t i o n i n t h e S t r a i t , but Frank I s l a n d and A m p h i t r i t e P o i n t r e c e i v e t h e br u n t of waves from the open ocean. T i d a l , t e m p e r a t u r e and s a l i n i t y c o n d i t i o n s i n t h e s e a r e a s a r e s i m i l a r t o those a t B o t a n i c a l Beach, a l t h o u g h t h e annua l range i n t e m p e r a t u r e and s a l i n i t y tends t o decrease g o i n g from A m p h i t r i t e P o i n t t o P o i n t No P o i n t , as a r e s u l t o f i n c r e a s e d m i x i n g w i t h deeper water i n t h e S t r a i t , 10 METHODS .Reproductive cycles.. The t i m i n g o f r e p r o d u c t i v e e v e n t s i n t h e f i e l d was s t u d i e d u s i n g t h e gonadal i n d e x , d e f i n e d as t h e p e r c e n t a g e wet weight o f t h e gonads t o t h e t o t a l l i v e body we i g h t . . T h i s method g i v e s a q u a n t i t a t i v e v a l u e f o r the r e p r o d u c t i v e s t a t e o f an a n i m a l , and i s p a r t i c u l a r l y u s e f u l f o r d e s c r i b i n g r e p r o d u c t i v e c y c l e s of s p e c i e s which show marked synchrony amongst a l l i n d i v i d u a l s (Moore, 1937; Gonor 1972; G i e s e & P e a r s e , 1974). However, the gonadal i n d e x method does not d e s c r i b e gametogenic e v e n t s . One does not known whether an i n c r e a s e i n t h e g o n a d a l i n d e x i s due to an advancement i n gametogenesis or t o the a c c u m u l a t i o n o f n u t r i e n t r e s e r v e s . F u r t h e r , some gametogenic e v e n t s may not r e s u l t i n a change i n the o v e r a l l s i z e of t h e gonads. An a c c u r a t e d e s c r i p t i o n o f gametogenic e v e n t s r e q u i r e s l e n g t h y h i s t o l o g i c a l and b i o c h e m i c a l p r o c e d u r e s . I n t h e p r e s e n t s t u d y n o t e s were made on t h e c o l o u r and f i r m n e s s o f the gonads, and t h e presence o r absence of young o o c y t e s and mature o v a , or the e x t e n t t o which sperm oozed from the d i s s e c t e d t e s t e s . I emphasized th e comparison o f g e n e r a l p a t t e r n s i n r e p r o d u c t i v e c y c l e s , and d e t a i l e d h i s t o l o g i c a l e v e n t s , a l t h o u g h o f i n t e r e s t , were not s t u d i e d . The gonadal i n d e x method i s based on t h e a s s u m p t i o n t h a t t h e g o n a d a l i n d e x i s independent of a n i m a l s i z e . , Gonor (1972) s t r e s s e d the i m p o r t a n c e of t e s t i n g t h i s assumption.„ I n s t u d y i n g s e a s o n a l t r e n d s i n r e p r o d u c t i v e a c t i v i t y , o n l y a d u l t a n i m a l s 11 s h o u l d be sampled, and i t i s d e s i r a b l e t o l i m i t the s i z e range of a d u l t a n i m a l s so t h a t v a r i a t i o n due t o s i z e i s as l i t t l e as p o s s i b l e . I n some s p e c i e s gonadal a c t i v i t y i n s m a l l e r a n i m a l s i s not synchronous w i t h l a r g e r a n i m a l s , and sometimes, g o n a d a l i n d i c e s d e c r ease s l i g h t l y i n v e r y l a r g e a n i m a l s {Gonor, 1972). To d e t e r m i n e a u s e f u l s i z e range f o r each s p e c i e s i n t h i s s t u d y , I p l o t t e d g o n a d a l i n d e x a r c s i n v a l u e s a g a i n s t body w e i g h t , u s i n g a n i m a l s c o l l e c t e d j u s t p r i o r t o t h e spawning p e r i o d . The a n g u l a r t r a n s f o r m a t i o n t o a r c s i n v a l u e s c o r r e c t s t h e gonadal i n d e x p e r c e n t a g e v a l u e s so t h a t t h e y a r e n o r m a l l y d i s t r i b u t e d ( S o k o l & H o h l f , 1969). For each s p e c i e s I t r i e d t o c o l l e c t a sample o f 10 or more a n i m a l s , w i t h i n t h e s i z e range determined by the above method, a t monthly or b i m o n t h l y i n t e r v a l s , or more f r e q u e n t l y when I a n t i c i p a t e d spawning. flhen a s p e c i e s was r a r e , as i n t h e case of I2££lia l i g n o s a a t F i r s t Narrows, o r when wave c o n d i t i o n s were extreme a t B o t a n i c a l Beach, i t was not always p o s s i b l e t o c o l l e c t 10 i n d i v i d u a l s of each s p e c i e s . The mean gonadal i n d e x and 95% c o n f i d e n c e l i m i t s of each sample were c a l c u l a t e d and t h e s e v a l u e s were p l o t t e d on a time s c a l e f o r each s p e c i e s . When spawning was imminent i n t h e f i e l d , a n i m a l s c o l l e c t e d i n the f i e l d c o u l d f r e q u e n t l y be i n d u c e d t o spawn by a d i s t u r b a n c e . To t e s t whether spawning c o u l d be i n d u c e d , I made a s t a n d a r d p r a c t i c e o f r e t u r n i n g a n i m a l s t o f r e s h seawater a f t e r a l l o w i n g them t o dry on paper t o w e l s f o r 15 minutes f o r weighing p u r p o s e s . , Spawning c o u l d o n l y be i n d u c e d i n t h i s way when i t »as about t o happen i n t h e f i e l d . 12 E n v i r o n m e n t a l c o n d i t i o n s ^ I n f o r m a t i o n on e n v i r o n m e n t a l c o n d i t i o n s i n the study a r e a s was o b t a i n e d from a number o f s o u r c e s . D a i l y t e m p e r a t u r e and s a l i n i t y measurements were made of i n c oming water a t the Vancouver P u b l i c Aquarium.. Ihe water i n t a k e was l o c a t e d 1 km from the c o l l e c t i o n s i t e a t F i r s t Narrows a t a depth of 6 m below MLWS, and i t i s l i k e l y t h a t t h e s e d a t a p r o v i d e a good r e c o r d of t h e c o n d i t i o n s t o which t h e f i e l d a n i m a l s were exposed. At B o t a n i c a l Beach water t e m p e r a t u r e s were not r e c o r d e d but d a i l y measurements o f s u r f a c e t e m p e r a t u r e s were a v a i l a b l e from l i g h t h o u s e s a t Sherringham P o i n t and A m p h i t r i t e P o i n t ( F i g . . 1 ; H o l l i s e r , 1971, 1972, 1974; Giovando & H o l l i s t e r , 1974; Giovando, P a c i f i c E n v i r o n m e n t a l I n s t i t u t e , p e r s . comm.), A comparison o f t e m p e r a t u r e s a t o r near B o t a n i c a l Beach at e a r l i e r d a t e s w i t h those f o r the same p e r i o d s a t Sherringham P o i n t and A m p h i t r i t e P o i n t i n d i c a t e d t h a t t e m p e r a t u r e s a t B o t a n i c a l Beach were c l o s e s t t o and s l i g h t l y warmer t h a n t h o s e a t Sherringham P o i n t , and almost always c o l d e r t h a n t h o s e a t A m p h i t r i t e P o i n t (Green, 1968; Crean & Agnes, 1968; H o l l i s t e r , 1968, 1971a, 1971b). Dr John S t o c k n e r , P a c i f i c E n v i r o n m e n t a l I n s t i t u t e (pers.,comm.) p r o v i d e d d a t a on t e m p e r a t u r e , s a l i n i t y and t h e abundance and s p e c i e s c o m p o s i t i o n of p h y t o p l a n k t o n a t s e v e r a l s t a t i o n s i n the v i c i n i t y of Vancouver and Howe Sound ( F i g . 1) d u r i n g 1973 and 1974. Mr Jae Shim, I n s t i t u t e o f Oceanography, U. B. C. ( p a r s . comm.), p r o v i d e d d a t a on p h y t o p l a n k t o n abundance i n S t r a i t of G e o r g i a and Juan de Fuca S t r a i t ( F i g . 1) i n 1973., I n a d d i t i o n I made some measurements of temperature and of c h l o r o p h y l l a c o n c e n t r a t i o n s i n t h e Vancouver a r e a i n 1973 and 1974, and a 13 thermograph r e c o r d o f temperature a t P o r t e a u d u r i n g t h e spawning p e r i o d i n 1973., Exp e r i m e n t s on spawning.. I n 1973 and 1974 l a b o r a t o r y e x p e r i m e n t s on spawning were conducted. On 30th March 1973, p r i o r t o spawning i n t h e f i e l d , S. d r o e b a c h i e n s i s and I . l i n e a t a were c o l l e c t e d a t F i r s t Narrows t o t e s t t h e e f f e c t or l i g h t and temperature on spawning. T h i r t y - f i v e t o f i f t y i n d i v i d u a l s o f each s p e c i e s were kept i n each o f f o u r 45 1 t a n k s under t h e f o l l o w i n g c o n d i t i o n s : d a r k - c o l d , l i g h t - w a r m , dark-warm, and l i g h t - c o l d . The two t a n k s i n the l i g h t were s e t up nex t t o a west f a c i n g window and p r o b a b l y r e c e i v e d more l i g h t t h a n a n i m a l s i n t h e f i e l d , but w i t h t h e same p h o t o p e r i o d i c i t y . A c o n t i n u o u s incoming s u p p l y of water m a i n t a i n e d t h e c o l d t a n k s a t 5.0±0.5 °C and the warm t a n k s a t 14.0±1.0 C e x c e p t f o r 2 o c c a s i o n s when t h e c o o l i n g system f a i l e d . D u r i n g A p r i l each t a n k was v i s u a l l y checked d a i l y f o r any i n d i c a t i o n of spawning, and on 12th A p r i l , 10 i n d i v i d u a l s o f each s p e c i e s were removed from each tank and t h e i r gonadal i n d i c e s determined. F i v e S . , d r o e b a c h i e n s i s were a l s o t a k e n from the dark-warm tank on 20th A p r i l . J On 2 9 t h A p r i l t h e e x p e r i m e n t s were t e r m i n a t e d and gonadal i n d i c e s were det e r m i n e d f o r t h e r e m a i n i n g a n i m a l s . I n 1974 S. d r o e b a c h i e n -s±s, T. .. l i n e a t a and T. i n s i g n i s were c o l l e c t e d on s e v e r a l d a t e s p r i o r to spawning and m a i n t a i n e d f o r 1—3 months under c o n s t a n t t e m p e r a t u r e c o n d i t i o n s i n t h e l a b o r a t o r y . L i g h t c o n d i t i o n s d u r i n g the 1974 e x p e r i m e n t s were not c o n t r o l l e d but v a r i e d w i t h o t h e r r e s e a r c h a c t i v i t i e s i n t h e l a b o r a t o r y . , I n a l l o f t h e above e x p e r i m e n t s t h e c h i t o n s were not f e d , e x c e p t f o r diatom scums which formed i n some t a n k s , and the u r c h i n s were 14 o c c a s i o n a l l y g i v e n p i e c e s of l a r a i a a r i a sp. Ex p e r i m e n t s were a l s o performed t o t e s t whether t h e presence o f p h y t o p l a n k t o n would i n d u c e spawning i n t h e l a b o r a t o r y . I n 1973 n a t u r a l p h y t o p l a n k t o n was c o l l e c t e d d a i l y a t J e r i c h o Beach w i t h a 50 p. mesh net and added t o tan k s c o n t a i n i n g groups of unspawned a n i m a l s . The e x p e r i m e n t a l a n i m a l s were from t a n k s which were s e t up on 30th March 1973 t o t e s t the e f f e c t s o f temperature and l i g h t . One group of S. d r o e b a c h i e n s i s i n a 12 1 c o n t a i n e r (14 °C) and two.groups o f 2* A±2.§§.ta i n two 4 1 c o n t a i n e r s (8 °C) were used. , These c o n t a i n e r s were m a i n t a i n e d w i t h o u t an incoming s u p p l y of water, but were g e n t l y a e r a t e d . Prom 2 1 t h - 2 7 t h A p r i l t h e water was changed d a i l y i n each c o n t a i n e r and f r e s h p h y t o p l a n k t o n was added u n t i l t h e water was s l i g h t l y murky. Spawning a c t i v i t y was no t e d and the mean g o n a d a l i n d e x of each group o f a n i m a l s on 27th A p r i l was compared t o i t s " s o u r c e " tank on 12th A p r i l and 29th A p r i l . I n 1974 f u r t h e r l a b o r a t o r y e x p e r i m e n t s on the e f f e c t s of p h y t o p l a n k t o n were conducted. A s u p p l y o f mature ^ r o n q y l o c e n -t r o t u s d r o e b a c h i e n s i s , T o n i c e l l a l i n e a t a , and T o n i e e l l a i n s i g n i s was c o l l e c t e d on 12th March and on 4 t h A p r i l a t F i r s t Narrows, and was m a i n t a i n e d a t 5.5 °C i n l a r g e t a n k s . . S i n c e adeguate q u a n t i t i e s of p h y t o p l a n k t o n c o u l d not be c o l l e c t e d w i t h a 50 p. mesh n e t a t J e r i c h o Beach u n t i l 29th A p r i l , e x p e r i m e n t s on these a n i m a l s were not s t a r t e d u n t i l t h i s date.,. D u r i n g t h e e x p e r i m e n t s f r e s h p h y t o p l a n k t o n was c o l l e c t e d e v e r y 2—3 days. Each experiment was r u n f o r 10 days. T e s t s were made on s i n g l e 15 a n i m a l s , u s i n g 1.2 1 c o n t a i n e r s f o r S. d r o e b a c h i e n s i s and 0.4 1 c o n t a i n e r s f o r T. l i n e a t a and T. i n s i g n i s . Every day the water i n each c o n t a i n e r was changed and a q u a n t i t y of p h y t o p l a n k t o n ( f i n a l c o n c e n t r a t i o n of 10 mg c h l o r o p h y l l a/m3) was added t o e x p e r i m e n t a l c o n t a i n e r s , but not t o t h e c o n t r o l s . A f t e r 17th May i t was not p o s s i b l e t o c o l l e c t a s u i t a b l e q u a n t i t y of p h y t o p l a n k t o n w i t h a n e t , and f r o z e n p l a n k t o n from 6 t h May was used a f t e r 19th May. The a d d i t i o n of sex p r o d u c t s i s one o f t h e most e f f e c t i v e ways o f i n d u c i n g spawning i n a v a r i e t y o f marine i n v e r t e b r a t e s ( G i e s e , 1959; L o o s a n o f f & D a v i s , 1963). Thus, f o r c o m p a r a t i v e p u r p o s e s , f o r each s p e c i e s I a l s o t e s t e d t h e e f f e c t o f an a d d i t i o n of a s m a l l q u a n t i t y o f sperm s u s p e n s i o n , u s i n g sperm shed by a n i m a l s i n the p l a n k t o n experiments.,, I d e ^ t i f i c a t i o n of the M o p a l i a sjaecies^,,- The genus Mojgalia i s i n need of r e v i s i o n and i d e n t i f i c a t i o n o f t h e v a r i o u s s p e c i e s i s u s u a l l y d i f f i c u l t f o r a person who has not spent c o n s i d e r a b l e t ime s t u d y i n g them. T h e r e f o r e , I w i l l d e s c r i b e i d e n t i f y i n g c h a r a c t e r i s t i c s which I have found u s e f u l . , M o g a l i a muscosa i s t h e most d i s t i n c t i v e s p e c i e s , owing t o t h e s t i f f b r i s t l e s which d e n s e l y c o v e r i t s g i r d l e . The p l a t e s are o f t e n worn t h r o u g h t o the c a l c a r e o u s l a y e r , and when the integument i s p r e s e n t i t i s brown i n c o l o u r and s c u l p t u r e d w i t h l o n g i t u d i n a l r i d g e s . M o g a l i a i i a n o s a has medium c o a r s e b r i s t l e s s c a t t e r e d o v e r i t s g i r d l e , and t h e r e a r e p i n k s p o t s at t h e base o f t h e b r i s t l e s . C o l o u r s t r e a k s , of b l u e - g r e y , brown and w h i t e i n v a r y i n g p r o p o r t i o n s , g i v e a d i s t i n c t i v e appearance to the smooth-s u r f a c e d p l a t e s . , The f o o t of M. I i g n o s a i s more r e d d i s h i n c o l o u r than t h a t o f the o t h e r M o p a l i a s p e c i e s . ., M f i a l i a - c i l i a t a 16 u s u a l l y has a wider g i r d l e and narrower p l a t e s than t h e o t h e r s p e c i e s . The g i r d l e has both f i n e g l a s s y b r i s t l e s and l a r g e r f l a t t e n e d b r i s t l e s . There are l o n g i t u d i n a l r i d g e s on the c e n t r a l a r e a s o f t h e p l a t e s , and t h e s e become more o b l i q u e and i r r e g u l a r on t h e l a t e r a l a r e a s . The p l a t e s u s u a l l y have a complex c o l o u r p a t t e r n w i t h shades of brown, g r e y , w h i t e , g r e e n , y e l l o w and orange, but sometimes , one c o l o u r predominates. Mo£alia h i n d s i i has a mo d e r a t e l y dense c o v e r i n g o f f i n e g l a s s y b r i s t l e s on i t s g i r d l e . The p l a t e s a r e dark brown i n c o l o u r , and t h e r e a r e l o n g i t u d i n a l and l a t t e r a l r i d g e s , g i v i n g a "basketweave" appearance. The p a l l i a l groove was y e l l o w - c o l o u r e d ( p a r t i c u l a r l y towards the p o s t e r i o r end) i n 95% o f the a n i m a l s I c o l l e c t e d weighing o v e r 10 g, and i n a s m a l l e r p r o p o r t i o n o f s m a l l e r a n i m a l s . T h i s c o l o u r a t i o n was not seen i n the o t h e r s p e c i e s . M o g a l i a l a e v i o r has a s p a r s e c o v e r i n g of g l a s s y b r i s t l e s on i t s g i r d l e . The s u r f a c e o f t h e p l a t e s i s smooth, but t h e r e i s t h e appearance o f f i n e l i n e s which l a t e r a l l y c r o s s t h e c e n t r a l a r e a s and then c u r v e p o s t e r i o r l y a c r o s s t h e l a t e r a l a r e a s . The p l a t e s a r e mostly grey brown i n c o l o u r , but i n most a n i m a l s t h e r e a r e some green markings and sometimes t h e r e a r e white s t r e a k s a c r o s s the c e n t e r o f t h e p l a t e s . 17 RESULTS R e l a t i o n o f Gonad S i z e t o an i m a l S i z e K a t h a r i n a t u n i c a t a . Gonadal i n d e x a r c s i n v a l u e s p l o t t e d a g a i n s t body weight a r e p r e s e n t e d f o r K. t u n i c a t a i n F i g u r e 2A, u s i n g a n i m a l s c o l l e c t e d a t B o t a n i c a l Beach and P o i n t No P o i n t p r i o r t o spawning i n 1971 and 1973. At B o t a n i c a l Beach no gonads were found i n 12 a n i m a l s w e i g h i n g 3.6 g o r l e s s ; t h e s m a l l e s t a n i m a l s w i t h mature gametes were a male and a female weighing 5.3 and 7.1 g r e s p e c t i v e l y ; and t h e l a r g e s t a n i m a l w i t h an immature gonad weighed 9.6 g., Animals l a r g e r t h a n 30 g had l a r g e r i p e gonads and t h e v a r i a t i o n i n a r c s i n v a l u e s remained s i m i l a r i n l a r g e r a n i m a l s . At P o i n t No P o i n t a n i m a l s had l a r g e r gonads, but gonad s i z e d i d not appear t o vary w i t h a n i m a l s i z e between 45—129 g. M o p a l i a h i n d s i i . Four M. h i n d s i i w e i g h i n g 1.3—2.4 g had no gonads, a male and a female , both w e i g h i n g 4.6 g, c o n t a i n e d mature gametes, and t h e s p r e a d o f gonadal i n d e x a r c s i n v a l u e s was s i m i l a r f o r a n i m a l s weighing 10-32 g ( F i g . 2 B j . M o p a l i a c i l i a t a . Gonadal i n d e x a r c s i n v a l u e s remained a t about t h e same l e v e l f o r a n i m a l s from F i r s t Narrows w e i g h i n g 4-19 g ( F i g . 2C). I n a c o l l e c t i o n of s m a l l e r a n i m a l s from Eagle Harbour on 23rd March 1973, a l l a n i m a l s , even a 0.6 g a n i m a l , c o n t a i n e d mature gametes, and one male wei g h i n g 2,4 g spawned i n the l a b o r a t o r y . 18 A 25 20 A 15 « O U < a "8 10 C o o Katharina tunlcata + I I I ° I I e + o o I 1 . • I O o Botanical Beach 0 28th March - 5th May 1971 1 6th A p r i l 1973 Point No Point + 25th May 1971 04niii 0 1 0 . 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 110 1 2 0 1 3 0 Weight (g) Fig. 2 A-H. Relation between the gonadal index percentage value (arcsin values) and the t o t a l l i v e animal weight f o r (A) Katharina tunicata, (B) Mopalia h i n d s i i . (C) Mofialia c i l i a t a , (D) Mopalia lignosa, (E) Mopalia l a e v i o r , (F) T o n i c e l l a l i n e a t a , (G) T o n i c e l l a i n s i g n i s , and (H) Strongylocentrotus droebachien-s i s . using animals c o l l e c t e d p r i o r to the spawning period. I 1 Mopalia h i n d s i i l I o I I e I I I • I I ' • I • ' I I e 1 , ( 1 I I I o I ° F i r s t Narrows 0 22nd February 1973 Eotanical Beach 1 9th March - 6th A p r i l 1973 0+-« i—!—i 1 1 1 1 1 1 0 5 10 15 20 25 30 35 Weight (g) 25 Mopalia c i l i a t a 20 CD O VI •< 15 10 54 • • • • • • • • • First Narrows • 21st February - 30th March 1973 Eagle Harbour • 23rd March - 4th April 1973 2 4 6 D 30 25 20 • o u I 15 R-F a 9 XM 8 10 12 14~ 16 18 20 Weight (g) Mopalia lignosa * • fa • 0 • • • o ' a + a. • Porteau f 8th April 1971 • 16th June 1971 + 7th April 1972 • 28th December 1972 • 8th May 1973 T 6 8 10 Weight (g) —r— 12 —r~ 14 76 25i 20 2 15 •< x a* "O c •g 10 c o 5^ 35i 30 25 20 15 10 54 Mopalia laevior o • • • • • , • 1 T O I First Narrows o 22nd January - 6th March 1973 Porteau • 8th February - 27th March 1973 10 15 20 25 Weight Cg) Tonicella lineata 30 ~35 i • _ 0 • I ' I » ~ B * ° „ * • n 0 O _ I , » II I o I i I o • o I I ,'l„ i . • i i i i 'i i i 0 • • • First Narrows } 20th April 1971 • 16th March - 20th April 1972 0 2nd February - 30th March 1973 Eagle Harbour 1 23rd March - 4th April 1973 0-fca-0 ~6~ T —i 8 -r-2 ; Weight (g) Tonicella Insignis c O •o c M 25 20H 15 cd 5 1(5 • 4 First Narrows f 21st January - 30th March 1973 Porteau • 8th February - 27th March 1973 Eagle Harbour I 23rd March 1973 4 6 8 Weight Cg) 10 72 40 35 30-25-20-15 10 5-I Strongylocentrotus droebachiensis e o ° oe e • • • a - • 8 » O e e o First Narrows o 12th March - 7th April 1974 ~20~ 40 60 80 100 120 140 160 180 200 220 Weight (gj 23 -Mogalia I i g n o s a . Gonadal i n d e x a r c s i n v a l u e s f o r 5 c o l l e c t i o n s o f M. I i g n o s a from P o r t e a u d u r i n g p e r i o d s when t h e mean gona d a l i n d e x was h i g h a re shown i n F i g u r e 2D., A l l a n i m a l s , even one .weighing 2.6 g, had l a r g e mature gonads, and gonadal s i z e d i d not appear t o vary w i t h body s i z e , , D u r i n g p e r i o d s when t h e mean gonadal i n d e x was low , f i v e 2,3—2.6 g a n i m a l s were f o u n d and each o f the s e c o n t a i n e d gonadal t i s s u e . ; M o g a l i a l a e v i o r . I n M. l a e v i o r from F i r s t Narrows and P o r t e a u t h e v a r i a t i o n i n go n a d a l i n d e x a r c s i n v a l u e s was r e l a t i v e l y u n i f o r m f o r a n i m a l s w e i g h i n g 9—35 g (Fxg. 2£). In a c o l l e c t i o n o f s m a l l e r a n i m a l s from E a g l e Harbour on 4th A p r i l 1973, 14 out of 17 a n i m a l s weighing 2-5 g c o n t a i n e d some mature gametes, but a r c s i n v a l u e s were not p l o t t e d f o r t h i s c o l l e c t i o n s i n c e spawning was n e a r l y f i n i s h e d on t h i s d a t e . M o g a l i a muscosa. S i n c e t h e r e d i d not appear t o be a p e r i o d when a l l a n i m a l s were i n peak r e p r o d u c t i v e c o n d i t i o n , I d i d not make a c o l l e c t i o n o f s m a l l M, .muscosa t o determine t h e s i z e a t s e x u a l m a t u r i t y . I n each o f the c o l l e c t i o n s made a t B o t a n i c a l Beach d u r i n g 1971-1973 t h e g o n a d a l i n d e x v a l u e s appeared to be independent o f a n i m a l s i z e w i t h i n t h e range 10—50 g. T o n i c e l l a l i n e a t a . T. l i n e a t a r e a c h e d s e x u a l m a t u r i t y a t a s m a l l e r s i z e t h a n t h e o t h e r c h i t o n s i n t h e p r e s e n t s t u d y ( F i g . , 2 F ) . I n a c o l l e c t i o n o f s m a l l a n i m a l s from E a g l e Harbour p r i o r t o spawning i n 1973 a l l a n i m a l s weighing 0.12 g or mOre c o n t a i n e d gametes, but 4 s m a l l e r a n i m a l s d i d not have gonads. Low g o n a d a l i n d e x a r c s i n v a l u e s were not found i n a n i m a l s weighing more than 1.5 g and t h e v a r i a t i o n i n v a l u e s was 24 r e l a t i v e l y u n i f o r m a f t e r 2 g., Two a n i m a l s weighing 0,4 and 0.7 g, r e s p e c t i v e l y , which were c o l l e c t e d a t B o t a n i c a l Beach on 21th June. 1970 spawned i n the l a b o r a t o r y a f t e r b e i n g d r i e d and r e w e t t e d , T o n i c e l l a i n s i g n i s , , F i g u r e 2G shows the g o n a d a l i n d e x a r c s i n v a l u e s f o r T. i n s i g n i s c o l l e c t e d a t F i r s t Narrows, P o r t e a u , and E a g l e Harbour p r i o r t o spawning i n 1973.., No gonads were found i n two a n i m a l s weighing 0,3 and 0,5 g r e s p e c t i v e l y , and a l l a n i m a l s w e i g h i n g 0.6 g or more c o n t a i n e d mature gametes. Gonadal index a r c s i n v a l u e s tended t o i n c r e a s e s l i g h t l y w i t h i n c r e a s i n g body weight between 3—12 g. ,, S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s . D u r i n g t h i s s t u d y I d i d not make a c o l l e c t i o n o f s m a l l S, d r o e b a c h i e n s i s i n o r d e r t o d e t e r m i n e the s i z e a t s e x u a l m a t u r i t y . . However, I made a few o b s e r v a t i o n s on t h i s s p e c i e s i n an e a r l i e r s tudy i n Newfoundland (Bimmelman, 1969), Animals s m a l l e r t h a n 20 mm i n t e s t d i a m e t e r ( e q u i v a l e n t t o about 3.9 g) d i d not c o n t a i n mature gametes d u r i n g a peak r e p r o d u c t i v e p e r i o d , but a n i m a l s 22 mm o r l a r g e r (about 5.0 g) c o n t a i n e d mature gametes. I n F i g u r e 2H gonadal i n d e x a r c s i n v a l u e s a r e p l o t t e d a g a i n s t body weight f o r l a r g e r a n i m a l s c o l l e c t e d a t F i r s t Narrows p r i o r t o spawning i n 1974. A r c s i n v a l u e s may d e c rease s l i g h t l y w i t h i n c r e a s i n g body weight. A summary of t h e o b s e r v a t i o n s on the s i z e a t s e x u a l m a t u r i t y f o r each of t h e s p e c i e s s t u d i e d , as w e l l as t h e s i z e ranges which I c o l l e c t e d f o r t h e s t u d i e s on r e p r o d u c t i v e c y c l e s , i s p r e s e n t e d i n T a b l e I . For some s p e c i e s a s m a l l e r s i z e range may have been p r e f e r a b l e t o reduce f u r t h e r t h e v a r i a t i o n i n 25 gonadal i n d e x v a l u e s i n t h e samples, but e x c l u d i n g t h e extremes would have reduced t h e sample s i z e too much. 26 Table I. Live weight (g) of animals at sexual maturity, and weight range c o l l e c t e d for the study of the reproductive c y c l e , for each of the species i n the present study. Size when a l l Size range c o l l e c t e d Size range with Smallest animal animals have f o r studies on no gonad with gametes " f u l l - s i z e d " gonads* reproductive cycles Katharina tunicata 0-3.6 Mopalia h i n d s i i  Mopalia c i l i a t a  Mopalia Iignosa  Mopalia l a e v i o r 0-2.4 5.3 4.6 0.6 2.6 1.6 30 10 4 2-4 8 30-130 10-35 4-20 4-19 8-35 Mopalia muscosa 10-50 T o n i c e l l a l i n e a t a 0-0.09 0.12 2-8 T o n i c e l l a i n s i g n i s 0-0.5 Strongylocentrotus droebachiensis 0-3.9. 0.6 5.0 20-25 3-12 30-150 * Size when a l l animals have near maximal gonadal index a r c s i n values (see F i g . 2). 27 R e p r o d u c t i v e C y c l e s K a t h a r i n a t u n i c a t a ( P i g . 3) The r e p r o d u c t i v e c y c l e o f K, t u n i c a t a at B o t a n i c a l Beach v a r i e d i n d i f f e r e n t y e a r s i n the f i v e . y e a r s t u d y p e r i o d . , D u r i n g 1970 and 1971 t h e r e was a r e g u l a r sequence o f e v e n t s ; a w e l l d e f i n e d spawninq p e r i o d i n June, a p e r i o d o f g o n a d a l i n a c t i v i t y d u r i n g the summer, and a p e r i o d of gonadal enlargement i n t h e l a t e autumn and w i n t e r . I n l a t e May 1970, p r i o r t o spawning, a l l a n i m a l s had mature gonads w i t h g o n a d a l i n d i c e s o f 3.8—9,5. D u r i n g June t h e mean gonadal i n d e x dropped from 6,1 t o 1.1, and a l l a n i m a l s c o l l e c t e d from l a t e June t o l a t e October had gonadal i n d i c e s of l e s s t h a n 2.5. Gonadal i n d e x v a l u e s i n c r e a s e d p r o g r e s s i v e l y from l a t e October 1970 t o March 1971., I n l a t e May 1971 one spent male and 20 r i p e i n d i v i d u a l s were c o l l e c t e d . By 10th June 30% of t h e a n i m a l s had i n d i c e s of l e s s than 2.0, and i n l a t e June a l l but one a n i m a l had s m a l l gonads. I t was unexpected t o f i n d a mature male w i t h an i n d e x o f 9.8 on 23rd J u l y , but o t h e r a n i m a l s c o l l e c t e d d u r i n g t h a t summer had s m a l l gonads. I n 1972 and 1973 K. t u n i c a t a had a markedly i r r e g u l a r r e p r o d u c t i v e c y c l e , and t h e r e may have been two spawning p e r i o d s . Gonadal growth i n the autumn o f 1971-72 was not as e x t e n s i v e as i n the p r e v i o u s year. F o r example, i n each o f t h e c o l l e c t i o n s from October t h r o u q h January 401 o f t h e a n i m a l s had Gonada l Index n ID tn H> 8 to m H- e IP t-" AO B |(+ >a e cr isr . ID IP> M l h P 13 O W IP H) W O i f l O Irt-O H-IC 3 0> 13 P ft H-& ID in P C M P H |rt C IP 3 rt-0, BT p (6 X ac ID p 3 o 3 P & p d) H-o a t ) o o & tr rt ID P K D cr H* P O P H P 3 H & 3* 8 (0 la rt-P er B H-•a w ID w N 0 as ID \0 p m O VI tr P O 3 O a. D H) •o p. o P-H- ID 3 3 rt- o (D ss o Hi O B O P-H 3 rt-H rt- W O • * • H- H3 M> B t r O XJ ID M 29 Botanical Beach Point No Point Amphitrite Point Frank Island Monterey Bay, C a l i f . Central C a l i f o r n i a Puget Sound, Wash. Monterey Area: Carmel Point Yankee Point Yankee Point Pescadero Point Yankee Point Yankee Point Yankee Point Yankee Point J ' F ' M ' A ' M ' J ' J ' A ' S ' O V D 1970 1971 1972 1973 1974 1971 1972 1971 1971 1932 1955 1956 1957 1958 1959 1959 1960 1961 1962 1963 1964 1965 1966 Katharina tunicata =1 present study Hewatt, 1933 Rickets & Calvin, 1968 1 = 1 Giese, 1959b; Giese, Tucker & Boolootian, 1959; Giese 6 Araki, 1962; Nimitz & Giese, 1964; Lawrence, Lawrence & Giese, 1965; Giese 6. Hart, 1967; Giese, 1969 Symbols |- large mature gonads, spawning not started -j small depleted gonads, spawning completed t • decrease i n the mean gonadal index fa beginning of spawning end of spawning approximate time of spawning ? <S observed egg or sperm release F i g . 4. Summary of spawning observations on Katfrari,na tunicat^. 30 g o n a d a l i n d i c e s of l e s s t h a n 2.0. I n mid—March 1972, 9 out of 10 a n i m a l s had r i p e gonads (and i n d i c e s g r e a t e r than 3 . 0 ) , and some spawning o c c u r r e d by 1 s t May, when a l l but one of t h e a n i m a l s c o l l e c t e d c o n t a i n e d s m a l l q u a n t i t i e s o f gametes (and had i n d i c e s o f 2,7 o r l e s s ) . There was some a d d i t i o n a l g o n a d a l growth d u r i n g May and June 1972 and on 14th June moderate q u a n t i t i e s o f gametes were found i n o n e - h a l f o f t h e a n i m a l s c o l l e c t e d . A second spawning o c c u r r e d sometime d u r i n g the summer, but t h e e x a c t time i s not known s i n c e a c o l l e c t i o n was not made u n t i l September.. I t may have o c c u r r e d between e a r l y May and l a t e June, t h e p e r i o d d u r i n g which t h e r e was spawning i n each o f t h e o t h e r f o u r y e a r s o f t h i s s t u d y . The drop i n the mean gonadal i n d e x from October t o November 1972 was p r o b a b l y due t o s a m p l i n g e r r o r r a t h e r than spawning. D u r i n g t h i s p e r i o d g o n a d a l growth i n males was w e l l i n advance o f t h a t i n f e m a l e s , and s i n c e more females were c o l l e c t e d i n November than i n O c t o b e r , t h e November i n d e x was l o w e r . . I n 1973 t h e r e was an i n c r e a s e i n t h e mean go n a d a l i n d e x s i m i l a r t o t h a t i n 1971, but t h e r e were agaxn two spawning p e r i o d s . The f i r s t spawning o c c u r r e d between 6 t h A p r i l and 4 t h May, and t h e second spawning was i n June. One male from 2nd J u l y had not y e t completed spawning but o t h e r i n d i v i d u a l s c o l l e c t e d i n J u l y and August c o n t a i n e d o n l y t r a c e s o f gametes (and had i n d i c e s o f l e s s than 2.5). I n l a t e A p r i l 1974 the mean gonadal i n d e x was 9.0, s u r p a s s i n g t h e peak v a l u e s i n the p r e v i o u s y e a r s . I n l a t e May 1974 spawning was underway and i t was completed by 20th June., 31 At Point No Po i n t 10 c o l l e c t i o n s of K. t u n i c a t a were made i n 1971 and one was made i n A p r i l 1972., The r e p r o d u c t i v e c y c l e here resembled c l o s e l y that during the same period at B o t a n i c a l Beach. The gonads grew r a p i d l y from February 1971 to a peak i n May. On 9th June 3 out of 10 animals were spent, and spawning was completed on 25th June.. In 1972 there was some e a r l y spawning c o r r e s p o n d i n g to the e a r l y spawning a t B o t a n i c a l Beach.. More than one-half o f the animals from 15th A p r i l 1972 had spent or p a r t l y spawned gonads. Gonadal index values at P o i n t No P o i n t were always l a r g e r than those at B o t a n i c a l Beach (see F i g s . 2A S 3). I do not know whether t h i s was due to the l a r g e r s i z e of animals at Poi n t No P o i n t , t o n u t r i t i o n a l d i f f e r e n c e s i n the two areas, or to other f a c t o r s . Three c o l l e c t i o n s of K. t u n i c a t a were made at A m p h i t r i t e P o i n t and at Frank I s l a n d i n 1971 ( F i g . ,1). , l a both areas spawning was near completion on 26th June and the mean gonadal index was 2.5±0.9 (95% co n f i d e n c e l i m i t s , n=10) at A m p h i t r i t e P o i n t and 2.8±1.1 (n=11) at Frank I s l a n d . On 10th J u l y the values were 1.5+0.5 (n=10) and 1.6+.Q.6 (n=11) , r e s p e c t i v e l y , and most animals d i d not c o n t a i n a t r a c e o f gametes. On 2nd October the gonads had s t a r t e d to develop and mean gonadal i n d i c e s were 2.3±0. 7 (n=10) and 2. 1±0.7 (n=9) , r e s p e c t i v e l y . , Thus, i n 1971, i t appears t h a t K. t u n i c a t a completed spawning at about the same time from Frank I s l a n d to P o i n t No P o i n t on the outer co a s t of Vancouver I s l a n d , and a l s o t h a t gonadal enlargement was s t a r t e d by October a t Frank I s l a n d , Amphitrite P o i n t and B o t a n i c a l Beach, 32 A summary of spawning o b s e r v a t i o n s on K a t h a r i n a t u n i c a t a from the p r e s e n t study and e a r l i e r s t u d i e s i s shown i n F i g u r e 4. The main spawning season i s J u n e - J u l y , but sometimes t h e r e i s a p a r t i a l spawning i n t h e s p r i n g . Shen the l a t t e r o c c u r r e d i n my st u d y i t was always f o l l o w e d be some a d d i t i o n a l g o n a d a l enlargement up t o t h e time o f t h e second spawning. I n summary, an a n n u a l r e p r o d u c t i v e c y c l e w i t h s p r i n g t o summer spawning appears t o be c h a r a c t e r i s t i c of K a t h a r i n a t u n -i c a t a from B r i t i s h Columbia t o Monterey. The gonads a r e always d e p l e t e d i n l a t e summer and gonadal growth o c c u r s from autumn through s p r i n g . Mop_alia h i n d s i i {.Fig., 5) !!• .^ifid§ii a a d a d i s t i n c t l y a n n u a l r e p r o d u c t i v e c y c l e i n bo t h t h e i n t e r t i d a l p o p u l a t i o n a t B o t a n i c a l Beach and i n t h e s u b t i d a l p o p u l a t i o n a t F i r s t Narrows, At B o t a n i c a l Beach i n 1972, spawning was completed i n June, s i n c e e v e r y a n i m a l c o l l e c t e d c o n t a i n e d few or no gametes.. D u r i n g the summer t h e r e was l i t t l e g o n a d a l enlargement, but a f t e r September t h e gonads grew s t e a d i l y t o a peak i n A p r i l 1973., A complete spawning o c c u r r e d i n A p r i l 1973 and a l l a n i m a l s c o l l e c t e d on 4 t h May 1973 had d e p l e t e d gonads. Only t h r e e c o l l e c t i o n s were made i n 1974. On 27th A p r i l 1974 t h e a n i m a l s c o l l e c t e d had e i t h e r p a r t l y spawned o r spent gonads, s u g g e s t i n g t h a t spawning was n e a r l y f i n i s h e d , and a l l a n i m a l s c o l l e c t e d i n May and June had spent Mopalia hinds Botanical Beach F i g . 5. Mean gonadal index and 955S confidence l i m i t s f o r flqpalia j j i n d s i i at Botanical Beach and F i r s t Narrows. Botanical Beach F i r s t Narrows San Francisco Bay Marin County, C a l i f . Monterey Bay, C a l i f . J ' F W A ' M ' J V A ' S ' O ' N ' D 1972 1973 1974 1972 1973 (-1974 1952 1953 1957 1956 1957 =1958= 1959 1960 Mopalia hindsii H present study h =1 Thorpe, 1962 _j Barnawell, 1954 J L Giese, 1959b; Giese, Tucker & Boolootian, 1959; Giese & Araki, 1962 JL F i g . 6. Summary of spawning observations on flo.j3aJ.ia, feislsii; syabols defined i n Figure U. 34 gonads. At F i r s t Narrows spawning was completed i n l a t e A p r i l 1972. Gonadal enlargement commenced i n t h e s p r i n g and by August t h e gonads were t w o — t h i r d s maximum s i z e . Gonadal growth i n t h e autumn and w i n t e r was s l o w e r and a peak was r e a c h e d i n January 1973., I n marked c o n t r a s t t o t h e a b r u p t spawning a t B o t a n i c a l Beach i n 1973, spawning a t F i r s t Narrows l a s t e d 2-3 months. I t was underway i n e a r l y March, when 1 spent animal and 6 w i t h i n t e r m e d i a t e — s i z e d gonads were c o l l e c t e d , b u t a l l a n i m a l s d i d not have spent gonads u n t i l 10th A p r i l . , In 1974 an a b r u p t spawning o c c u r r e d . , A few p a r t l y spawned a n i m a l s were f i r s t c o l l e c t e d on 4 t h A p r i l and spawning was completed by 15th A p r i l . A l i s t o f spawning o b s e r v a t i o n s on M. h i n d s i i i n t h e p r e s e n t study and e a r l i e r s t u d i e s i s shown i n F i g u r e 6. I n San F r a n c i s c o Bay, B a r n a w e l l (1954) o b s e r v e d a r e p r o d u c t i v e c y c l e i n i * h i n d s i i s i m i l a r t o t h a t observed i n my s t u d y . There was a p r o g r e s s i v e i n c r e a s e i n t h e p r o p o r t i o n o f a n i m a l s w i t h l a r g e gonads from l a t e August t o November 1952, and the m a j o r i t y of a n i m a l s c o l l e c t e d from J a n u a r y - A p r i l 1953 had l a r g e gonads. S u b s e q u e n t l y , spawning o c c u r r e d , s i n c e most or the a n i m a l s c o l l e c t e d i n flay had s m a l l gonads. Egg r e l e a s e i n fi. ...hindsii from two l o c a t i o n s i n M a r i n County, C a l i f o r n i a , was seen i n l a t e October by Thorpe (1962)., I n t h e Monterey a r e a M. h i n d s i i spawned a b r u p t l y i n March 1957, but not i n t h e f o l l o w i n g y e a r s ( G i e s e , Tucker & B o o l o o t i a n , 1959; G i e s e & A r a k i , 1962). There was a g r a d u a l d e c l i n e i n the mean g o n a d a l i n d e x from November 1957 t o J u l y 1958, and t h r e e b r e e d i n g p e r i o d s o c c u r r e d between 35 November 1959 and l a t e s p r i n g 1960., I n summary, M o p a l i a h i n d s i i i n B r i t i s h C o lumbia spawns a n n u a l l y i n M a r c h - A p r i l , w h i l e i n C a l i f o r n i a i t sometimes spawns over extended p e r i o d s from e a r l y w i n t e r t o l a t e spring.„ i°£alia c i l i a t a ( F i g . 7) The r e p r o d u c t i v e c y c l e of M. c i l i a t a was s t u d i e d i n g r e a t e s t d e t a i l a t F i r s t Narrows. The d a t a from 1972-1973 showed a r e g u l a r c y c l e to be p r e s e n t , even though o n l y a few a n i m a l s were found on some c o l l e c t i o n d a t e s . Gonadal enlargement i n 1972 proceeded g r a d u a l l y a f t e r June r e a c h i n g a peak i n Ja n u a r y 1973., A l l a n i m a l s c o l l e c t e d i n March 1973 had mature gonads, and one male i n each o f the two March c o l l e c t i o n s d i s c h a r g e d some sperm s u g g e s t i n g t h a t spawning was imminent. The . g o n a d a l i n d i c e s dropped a b r u p t l y i n e a r l y A p r i l and every animal from t h e 14th A p r i l c o l l e c t i o n had d e p l e t e d gonads. I n 1974 t h e r e may have been some summer spawning i n a d d i t i o n t o t h e main s p r i n g spawning. ., A l l a n i m a l s c o l l e c t e d on 20th A p r i l and e a r l i e r had mature gonads, but o n e — h a l f o f t h e a n i m a l s c o l l e c t e d on 24th A p r i l had spent gonads., I t was unexpected t o f i n d 4 out o f 5 a n i m a l s on 7th May w i t h l a r g e mature gonads. P o s s i b l y spawning was d e l a y e d i n some l o c a l i z e d a r e a s a t F i r s t Narrows and the v a r i a t i o n i n the da t a was due to sam p l i n g e r r o r . Most o f the a n i m a l s c o l l e c t e d i n June and J u l y had mature g o n a d a l t i s s u e s , but many of t h e s e a n i m a l s had s m a l l — t o i n t e r m e d i a t e - s i z e d gonads. By 18th September 10 o u t of 13 Mopa l ia c i l i a t a Botanical Beach H 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 M J J A S O N D J F M A M J J A S O N D J F M A M J J A S 1972 I 1973 I 1974 F i g . 7. Bean gonadal index and 95% confidence l i m i t s f o r Mopalia c i l i a t a at F i r s t Narrows and Botanical Beach. Botanical Beach Fir s t Narrows Eagle Harbour San Francisco Bay California J F M A M J J A S O N D Mopalia c i l i a t a 1974 1971 1972 1973 1974 1973 1953 1956 1957 I960 1961 Thorpe, * ° 1962 J? J L J L present study H Barnawell, 1954 ? J I I I F i g . 8. Summary of spawning observations on Mopalia c i l i a t a , : symbols defined i n Figure H, 37 a n i m a l s had s p e n t gonads., On 20th A p r i l 1971, 2 M. c i l i a t a w i t h d e p l e t e d gonads were c o l l e c t e d a t F i r s t Narrows. On the assumption t h a t t h i s s p e c i e s i s mature d u r i n g the w i n t e r , as i n 1972 and 1973, spawning i n 1971 p r o b a b l y o c c u r r e d i n March or A p r i l . , At Eagle Harbour two c o l l e c t i o n s o f M. c i l i a t a - were made near the time of t h e 1973 spawning season. The gonadal i n d e x decreased from 11.8±1. 9 (n=10) on 23rd March, t o 10.-2±2. 8 (n=9) on 4 t h A p r i l , and a l l a n i m a l s c o n t a i n e d l a r g e q u a n t i t i e s of mature gametes. Here, spawning p r o b a b l y o c c u r r e d a t about t h e same time as a t F i r s t Narrows . At B o t a n i c a l Beach f o u r c o l l e c t i o n s o f M. c i l i a t a were made i n 1974., On 27th A p r i l a l l a n i m a l s c o l l e c t e d had l a r g e mature gonads.. The mean gonadal i n d e x dropped a b r u p t l y i n May, and a l l a n i m a l s c o l l e c t e d i n June and J u l y were spent. A summary of spawning o b s e r v a t i o n s on M. c i l i a t a i s shown i n F i g u r e 8. In B r i t i s h Columbia spawning o c c u r r e d from l a t e March t h r o u g h A p r i l , e x c e p t i n 1974 when t h e r e was some d e l a y e d spawning a c t i v i t y . I n San F r a n c i s c o Bay, B a r n a w e l l (1954) r e p o r t e d t h a t a n i m a l s w i t h l a r g e gonads were found i n a l l s e a s o n s , but h i s data show a d e c r e a s e i n t h e p r o p o r t i o n of a n i m a l s w i t h l a r g e gonads from A p r i l t o J u l y , which s u g g e s t s t h a t spawning o c c u r r e d i n t h i s p e r i o d . From v a r i o u s l o c a t i o n s i n C a l i f o r n i a , Thorpe (1962) r e p o r t e d 20 o b s e r v a t i o n s of i n d i v i d u a l s spawning: 12 were i n t h e p e r i o d 2 1 t h F e b r u a r y - 2 1 t h Harch, 1 was on 15th J u l y , and 7 were i n t h e p e r i o d 2 5 t h 38 September-20th November. Thus, Mojgalia c i l i a t a spawns from l a t e w i n t e r t h r o u g h s p r i n g i n B r i t i s h C olumbia, but i n the s o u t h e r n p a r t o f i t s range i t may a l s o spawn i n t h e summer and autumn. M o p a l i a l i g n o s a ( F i g . .9) At P o r t e a u M. . l i g n o s a appeared t o spawn t w i c e i n 1971. Spawning was imminent on 8th A p r i l , when a l l a n i m a l s had l a r g e mature gonads and 4 males spawned i n t h e l a b o r a t o r y , but one month l a t e r 7 out of 10 a n i m a l s had i n t e r m e d i a t e - t o s m a l l - s i z e d gonads. S u b s e q u e n t l y t h e r e was some gonadal g r o w t h , and a d d i t i o n a l spawning o c c u r r e d sometime between mid—June and l a t e August., In 1972 one c o l l e c t i o n of 4 a n i m a l s was made on 7 t h A p r i l . , , Three males had gonadal i n d i c e s o f 15.3-19.5, and one female had an i n d e x o f 7.5. . These 4 a n i m a l s appeared mature but c o u l d not be i n d u c e d t o spawn i n the l a b o r a t o r y . , I n 1973 a n i m a l s w i t h l a r g e gonads were found i n February and spawning o c c u r r e d sometime p r i o r t o 10th A p r i l , when t h e a n i m a l s c o n t a i n e d o n l y s m a l l q u a n t i t i e s of gametes. I n t e r p r e t a t i o n o f t h e r e p r o d u c t i v e c y c l e o f M, . l i g n o s a a t F i r s t Narrows i s c o m p l i c a t e d by both t h e s m a l l s i z e o f many o f the c o l l e c t i o n s and the i r r e g u l a r sequence o f e v e n t s . , I n 1971 spawning may have o c c u r r e d i n A p r i l , s i n c e 1 a n i m a l from 2 0 t h A p r i l r e l e a s e d sperm i n t h e l a b o r a t o r y . I n 1972, 3 spent a n i m a l s were found i n March., Animals w i t h l a r g e r gonads were found i n A p r i l t h r o u g h June 1972 and some spawning may have 39 16 14 12 X 0} XJ 10 c 8 ro c o 6 O 4 2 0-10 \ 1-° \ 10 \ P o r t e a u V . \6 Mopal ia I ignosa F i r s t N a r r o w s •J : • 14 10 \ P o r t e a u V 8 A M j j A 'S 'O 'N 'D 'J 'F 'M 'A 'M 'J 'J 'A 'S 'O 'N 'D 'J 'F 'M 'A ' 1971 I 1972 | 1973 F i g . 9. Bean gonadal index and 95X confidence l i m i t s f o r Mopalia lASSosa. at Porteau, and mean gonadal index and gonadal i n d i c e s ot each animal c o l l e c t e d at F i r s t Narrows. Porteau F i r s t Narrows California Monterey, C a l i f . J " F ' M ' A ' M ' J ' J ' A ' S ' O ^ N P D Mopalia Iignosa 1971 1972 1973 1971 1972 1973 1957 1974 <t9 rf? present study Thorpe, 1962 J L I I L Watanabe & Cox, 1975 -1 1 I I L F i g . 10. Summary of spawning observations on Mopalia Iignosa-symbols defined i n Figure 4. — - — a ~' 40 o c c u r r e d i n t h e summer, s i n c e i n August the an i m a l s c o l l e c t e d c o n t a i n e d s m a l l e r q u a n t i t i e s o f gametes. There was no e v i d e n c e of spawning i n November 1972 and Ja n u a r y 1973, but by l a t e A p r i l 1973 the gonads were n o t a b l y s m a l l e r and c o n t a i n e d o n l y t r a c e s of gametes. The a m p l i t u d e o f t h e gona d a l i n d e x c y c l e was much s m a l l e r a t F i r s t Narrows than a t P o r t e a u . , At peak p e r i o d s g o n a d a l i n d e x v a l u e s a t P o r t e a u were f r e q u e n t l y 9-13 and o c c a s i o n a l l y n e a r l y 20, whereas a t F i r s t Narrows an i n d e x o f 9 o c c u r r e d o n l y t w i c e , and peak v a l u e s were u s u a l l y about 6. There are l i t t l e d a ta on spawning o f fi. . l i g n o s a i n the l i t e r a t u r e ( F i g . 10)., On the open c o a s t near San F r a n c i s c o Bay, Thorpe (1962) o b s e r v e d spawning i n 5 a n i m a l s i n t h e p e r i o d 2 7 t h F e b r u a r y - 1 3 t h March 1957, and i n t h e Monterey a r e a , i a t a n a b e and Cox (1975) i n d u c e d some a n i m a l s t o spawn i n A p r i l - M a y 1974 by k e e p i n g them i n s t a l e w a t e r , but spawning c o u l d not be i n d u c e d by o t h e r methods. I n summary, M o p a l i a - l i g n o s a appears t o spawn i n l a t e w i n t e r - e a r l y s p r i n g , and a second spawning may o c c u r i n t h e e a r l y summer. Mo£alia l a e v i o r ( F i g . , 11) II* i^§li2£ w a s examined o n l y i n t h e s u b l i t t o r a l p o p u l a t i o n s a t P o r t e a u and F i r s t Narrows. ,, At P o r t e a u spawning was i n p r o g r e s s and near c o m p l e t i o n when t h e f i r s t c o l l e c t i o n was made on 8 t h A p r i l , 1971. The mean gona d a l i n d e x was l o w , but 4 a n i m a l s r e l e a s e d gametes i n the l a b o r a t o r y and 3 o f t h e s e had 41 Mopal ia laevior i , F i r s t N a r r o w s 1/ F i g . 11. Mean gonadal index and 95% confidence l i m i t s f o r l2E§lil l a e v i o r at Porteau and F i r s t Narrows. Porteau Fi r s t Narrows Eap.le Harbour j ' F ' M ' A ' M ' j 1 J ' A ' S ' O ' N ' D Mopalia laevior present study 1971 94 1972 1973 M 1972 1973 197.4 1973 J L J_ I L F i g . 12. Summary of spawning observations on Mopalia l a e v i o r : symbols defined i n Figure 4. 42 i n t e r m e d i a t e — s i z e d gonads., I n 1972 spawning was d e l a y e d , s i n c e a l l a n i m a l s c o l l e c t e d on 7 t h A p r i l , w i t h t h e e x c e p t i o n of 1 p a r t l y spawned male, had l a r g e gonads. I n 1973 t h e r e was an abru p t spawning a t P o r t e a u . On 27th March o n l y 1 s p e n t a n i m a l was c o l l e c t e d , and on 10th A p r i l t h e p o p u l a t i o n had n e a r l y completed spawning., At F i r s t Narrows t h e r e was no i n d i c a t i o n o f spawning i n t h e c o l l e c t i o n s from March and A p r i l 1972, but t h e 1 a n i m a l c o l l e c t e d on 8th May was s p e n t , as were a l l a n i m a l s c o l l e c t e d i n June and August. The gonads e n l a r g e d r a p i d l y durng t n e autumn o f 1972 and r e a c h e d peak s i z e by l a t e J a n uary 1973., One spent a n i m a l was found on 6 t h March and a n o t h e r on 30th March.„ I n the l a t t e r c o l l e c t i o n 4 a n i m a l s spawned i n response to b e i n g d r i e d and r e w e t t e d . , There was an a b r u p t spawning i n e a r l y A p r i l 1973 and o n l y s m a l l q u a n t i t i e s o f gametes o r none a t a l l remained i n a n i m a l s c o l l e c t e d on 14th A p r i l . I n 1974 the spawning p e r i o d a t F i r s t Narrows was p o o r l y d e f i n e d and t h e r e appears t o have been spawning i n A p r i l and May and perhaps a l s o i n t h e summer p e r i o d . The most s t r i k i n g drop i n t h e mean gona d a l i n d e x o c c u r r e d between 10th—24th A p r i l , but the d a t a were e r r a t i c and a h i g h p r o p o r t i o n o f unspawned a n i m a l s was l a t e r c o l l e c t e d on 3 0 t h A p r i l and 7 t h May. Animals c o l l e c t e d on d i f f e r e n t d a t e s , and pr o b a b l y from s l i g h t l y v a r i e d l o c a l i t i e s , d i f f e r e d i n the e x t e n t t o which they had spawned, s u g g e s t i n g t h a t t h e p o p u l a t i o n a t F i r s t Narrows d i d not spawn i n synchrony i n 1974., A l l a n i m a l s i n the 18th September c o l l e c t i o n had s p e n t gonads. One c o l l e c t i o n o f M. l a e v i o r was made a t E a g l e Harbour on 43 4th A p r i l 1973. The mean gonadal i n d e x was 1. 4±0. 7 (n=5) i n d i c a t i n g t h a t spawning was completed. There are no spawning d a t a on M o g a l i a l a e v i o r i n the l i t e r a t u r e . The da t a from P o r t e a u and F i r s t Narrows show a d i s t i n c t a n n u a l c y c l e w i t h u s u a l l y an a b r u p t spawning i n t h e s p r i n g ( F i g . 12). H2£dlia museosa ( F i g . 13) Midway i n t h e s t u d y o f M. muscosa, I r e a l i z e d t h a t t h e r e p r o d u c t i v e c o n d i t i o n o f a n i m a l s v a r i e d g r e a t l y i n d i f f e r e n t p o o l s a t any one t i m e , and s i n c e a n i m a l s from d i f f e r e n t p o o l s on the same c o l l e c t i o n d a t e s were not s e p a r a t e d , mean gonadal i n d i c e s were not c a l c u l a t e d . F i g u r e 13 shows the g o n a d a l i n d e x v a l u e s of each a n i m a l c o l l e c t e d on 15 da t e s a t B o t a n i c a l Beach d u r i n g 1971-1973. At a l l t i m e s i n t h e y e a r mature and spent a n i m a l s were found a t B o t a n i c a l Beach and no peak p e r i o d o f r e p r o d u c t i v e a c t i v i t y was e v i d e n t . , Animals w i t h i n any one p o o l tended t o have s i m i l a r g onadal i n d i c e s . F o r example, on 4 t h August, 5 a n i m a l s from a p o o l a t 2.6 m above MLSS had i n d i c e s r a n g i n g from 1,9—4.2, whereas 5 a n i m a l s from a p o o l a t 1.8 m had v a l u e s of 5.0—8.6. T h i s c h i t o n s p e c i e s l i v e s h i g h e r i n the i n t e r t i d a l r e g i o n t h a n t h e o t h e r c h i t o n s s t u d i e d , and t h e v a r i a t i o n i n t h e r e p r o d u c t i v e c o n d i t i o n o f a n i m a l s i n d i f f e r e n t p o o l s was p r o b a b l y r e l a t e d t o such f a c t o r s as p o o l s i z e , i n t e r t i d a l h e i g h t and f o o d c o n d i t i o n s . To dete r m i n e s e a s o n a l t r e n d s i n .M. muscosa i t would be n e c e s s a r y t o make c o l l e c t i o n s 44 Mopalia muscosa B o t a n i c a l B e a c h H 1 1 1 1 1 1 1 0 I i I I l 1 1 1 1 1 1 1 1 1 1 1 1—7~*~T 0 1 - ' • • 1 • • • • • s O N D J F M A M J J F M A M J J A 1971 A S O N D J F M A M J J A S O N 1 9 7 2 I 1973 P i g . 13. Gonadal i n d i c e s of each i n d i v i d u a l of flooalia flascosa c o l l e c t e d at Botanical Beach. 45 Botanical Beach Monterey Bay, C a l i f . Pug e t S ound, Wa sh. Corona del Mar, C a l i f . San Francisco Eay Santa Monica Bay: Flat Rock Sunset Point Latigo Point Monterey, C a l i f . J ' F ' M ' A ' M ' J ' J ' A ' S ' O ' N ' D Mopalia muscosa i Q 7 i 1Q7-3 Animals with mature gonads „„„ . _ , 1971-1973 f„„„j f. , ^ t, present study round throughout the year 3 1932 Rickets & Calvin, 1968 — — MacGinitie & MacGinitie, 1949 1953 ? Hewatt, 1933 Animals with mature gonads found throughout the year Barnawell, 1954 1960 1961 1960 1961 [i960 1961 1974 -I L Watanabe & Cox, 1975 ± Boolootian, 1964b; Monroe & Boolootian, 1965 Pig. 14. Summary of spawning observations on flopalja muscosa: symbols defined i n Figure 4. 46 t h r o u g h o u t t h e year from a s p e c i f i c p o o l which c o n t a i n e d enough a n i m a l s t o s u s t a i n t h i s amount o f s a m p l i n g . I n the l i t e r a t u r e t h e r e a re r e p o r t s o f obser v e d spawnings or o f gonadal i n d e x decreases i n M. muscosa i n a l l seasons o f the year ( F i g . 14). B a r n a w e l l (1954) found a h i g h p r o p o r t i o n of i n d i v i d u a l s w i t h l a r g e gonads t h r o u g h o u t t h e year i n San F r a n c i s c o Bay. I n Santa Monica Bay, C a l i f o r n i a , B o o l o o t i a n (1964b) and Monroe and E o o l o o t i a n (1965) i n d i c a t e d t h a t major drops i n t h e mean gonadal i n d e x i n t h r e e d i f f e r e n t p o p u l a t i o n s o c c u r r e d d u r i n g the w i n t e r and s p r i n g , a l t h o u g h t h e i r d a t a a l s o showed t h a t a n i m a l s w i t h mature gametes were found even when t h e mean gonadal i n d e x was low. I t would appear t h a t M o p a l i a 1useosa spawns t h r o u g h o u t t h e y e a r , and t h a t t h e e x t e n t of r e p r o d u c t i v e a c t i v i t y i s r e l a t e d t o e n v i r o n m e n t a l c o n d i t i o n s i n t h e immediate v i c i n i t y where t h e a n i m a l s a r e found. T o n i c e l l a l i n e a t a ( F i g . 15) O b s e r v a t i o n s on t h e r e p r o d u c t i v e c y c l e of T., l i n e a t a were made a t t h r e e l o c a t i o n s o v e r f o u r b r e e d i n g s e a s o n s . At B o t a n i c a l Beach i n l a t e May 1971, 2 out of 10 a n i m a l s were s p e n t , i n d i c a t i n g t h a t spawning had begun., One month l a t e r a l l a n i m a l s were s p e n t . , I n 1972 t h e r e was a complete spawning between mid-March and m i d - A p r i l . Two spawning p e r i o d s o c c u r r e d i n 1973., The major drop i n t h e mean gonadal i n d e x o c c u r r e d d u r i n g t h e p e r i o d 6 t h A p r i l - 4 t h May, and a i l a n i m a l s from t h e l a t t e r d a t e c o n t a i n e d s m a l l q u a n t i t i e s of gametes., A n i m a l s from 47 24 20 16 12 8 0 Tonicella l ineata 12 15 15| jFirst N a r r o w s 14 Botanica l B e a c h • H — - H 1 I • I 1 1 1 1 1 1 1 1 1 1 (-A M J J A S O N D J FM A ' M ' J ' J ' A ' S ' O ' N V J ' F ' M ' A ' M V J ' A ' S ' O ' N ' D V F ' M ' A ' M V J ' A ' S 1971 I 1972 | 1973 | 1974 F i g . 15. Mean gonadal index and 9531 confidence l i m i t s f o r S g s i c e l l a l i n e a t a at Botanical Beach, F i r s t Narrows and Porteau. 48 Botanical Beach Porteau F i r s t Karrows Eagle Harbour San Pedro Point, C a l i f . San Juan Island, Wash. Oregon: Boiler Bay Yaquina Head Yaquina Head Yaquina Head Strawberry H i l l Cape Argo Cape Argo I I I I 1 1 1 1 1 1 ~1 J F M A M J J A S O N D 1970 1971 1972 1973 1974 1971 1972 1973 1971 . 1972 1973 1974 1973 1957 1955 1958 1959 1968 1969 1970 1968 1967 1968 1969 1968 1968 \- 1969 Toni c e l l a lineata o"? =4 present study o"9 Thorpe, 1962 o*S> Barnes, 1972 F i g . 16. Summary of spanning observations on To n i c e l l a l i n e a t a -symbols defined i n Figure 4. ~ * 49 2 1 s t May and 4th June c o n t a i n e d medium t o l a r g e . q u a n t i t i e s of gametes, s u g g e s t i n g t h a t t h e r e was some a d d i t i o n a l gamete p r o d u c t i o n . The second spawning o c c u r r e d a f t e r 4 t h June and a l l a n i m a l s i n J u l y and August had d e p l e t e d gonads. ,, In 1974 t h e mean gonadal i n d e x dropped i n l a t e A p r i l - e a r l y May, and a n i m a l s c o l l e c t e d on 23rd May and l a t e r had spen t gonads. At P o r t e a u , spawning i n 1971 was p r o b a b l y i n p r o g r e s s on 8th A p r i l when 1 a n i m a l i n 5 c o l l e c t e d had a s m a l l gonad, and was n e a r l y f i n i s h e d on 8th May when 9 a n i m a l s i n 10 had d e p l e t e d gonads. I n 1972 o n l y one c o l l e c t i o n was made and t h i s was on 7th A p r i l . One a n i m a l had a d e p l e t e d gonad and 10 o t h e r s had l a r g e . r i p e gonads, s u g g e s t i n g t h a t spawning had begun.. An e a r l y spawning o c c u r r e d i n 1973. On 27th March 1973 spawning was imminent, s i n c e 1 male spawned i n the l a b o r a t o r y from b e i n g h a n d l e d , and on 10th A p r i l spawning was n e a r l y f i n i s h e d . A t F i r s t Narrows spawning o c c u r r e d a t about t h e same t i m e i n both 1971 and 1972. On 20th A p r i l 1971 the 22 a n i m a l s c o l l e c t e d had mature gonads and t w o - t h i r d s o f the s e spawned a f t e r b e i n g d r i e d and r e w e t t e d . On 17th May a l l a n i m a l s had d e p l e t e d gonads. In 1972 spawning c o u l d not be i n d u c e d i n the l a b o r a t o r y i n a n i m a l s from 20th A p r i l , but 2 a n i m a l s had d e p l e t e d gonads,, F o l l o w i n g t h i s t h e mean gonadal i n d e x dropped a b r u p t l y and a l l a n i m a l s from 8th May were spent.,. I n 1973 %* l i n e a t a spawned s e v e r a l weeks e a r l i e r . The e v e n t s were f o l l o w e d c l o s e l y . On 30th March the mean gonadal i n d e x was 14.5, and a l l a n i m a l s had l a r g e gonads. By 14th A p r i l t h e i n d e x had dropped t o 10,1 and o n e - h a l f of the a n i m a l s had p a r t l y 50 spawned gonads. The i n d e x on 17th A p r i l was 5.1 w i t h a l l a n i m a l s h a v i n g s m a l l - t o medium-sized gonads, and on 2 8 t h A p r i l s e v e r a l a n i m a l s c o n t a i n e d b a r e l y a t r a c e of gametes. I n 1974 !• l i n e a t a spawned o v e r a much l o n g e r p e r i o d than i n t h e p r e v i o u s y e a r s . , The a n i m a l s had l a r g e r i p e gonads on 10th A p r i l and e a r l i e r , b u t t h e r e was a de c r e a s e i n the mean gon a d a l ind e x a f t e r t h i s d a t e u n t i l 7 t h May, as t h e p r o p o r t i o n o f a n i m a l s w i t h d e p l e t e d gonads i n c r e a s e d . _ Spawning a c t i v i t y c o n t i n u e d i n t o the summer. N e a r l y h a l f o f the a n i m a l s c o l l e c t e d i n June and J u l y c o n t a i n e d r e l a t i v e l y l a r g e q u a n t i t i e s o f gametes and a n i m a l s from J u l y spawned from b e i n g handled. By 18th September a l l but 1 a n i m a l i n 13 had d e p l e t e d gonads. A t E a g l e Harbour one c o l l e c t i o n o f T. l i n e a t a was made on 4 t h A p r i l 1973. One a n i m a l i n 18 (of the a d u l t a n i m a l s c o l l e c t e d w eighing o v e r 1.5 g) had spawned, s u g g e s t i n g t h a t spawning had b a r e l y begun (mean gonadal i n d e x 14.0±2.8). F i g u r e 16 summarizes spawning o b s e r v a t i o n s on T_.ylij3ea.ta, The major drop i n gonadal i n d i c e s o c c u r r e d i n A p r i l — e a r l y . May, e x c e p t f o r the June spawning a t B o t a n i c a l Beach i n 1971, and the l a t e M a y — e a r l y June spawning which o c c u r r e d a t San Juan I s l a n d , Washington, i n 1968 and 1969 (Barnes, 1972). At B o t a n i c a l Beach i n 1973 and a t F i r s t Narrows i n 1974, t h e r e was some a d d i t i o n a l g onadal development and spawning a f t e r the major A p r i l spawning. T h i s d i d not o c c u r when t h e r e was a complete spawning i n t h e s p r i n g , which l e f t a l l a n i m a l s w i t h s m a l l d e p l e t e d gonads. The o b s e r v a t i o n s of spawning i n l a t e June and e a r l y August a t San Juan I s l a n d i n 1955, 1968 and 1969 (Barnes, 1972) were p r o b a b l y 51 made d u r i n g summer embryology c o u r s e s a t the F r i d a y Harbor L a b o r a t o r i e s so t h a t e a r l i e r e v e n t s i n t h e s e y e a r s were n o t f o l l o w e d . Spawning was not always synchronous i n d i f f e r e n t l o c a t i o n s . F o r example, Barnes (1972) found t h a t spawning o c c u r r e d a month e a r l i e r i n Oregon than a t San Juan I s l a n d i n both 1968 and 1969, I n t h e p r e s e n t study spawning a t B o t a n i c a l Beach was always e a r l i e r o r l a t e r than a t F i r s t Narrows and P o r t e a u , and the p o p u l a t i o n a t F i r s t Narrows always t e n d e d t o l a g b e h i n d t h e p o p u l a t i o n a t P o r t e a u . I n summary, T o n i c e l l a l i n e a t a has a d i s t i n c t l y a n n u a l r e p r o d u c t i v e c y c l e , The gonads a r e s m a l l i n mid-summer and gonadal growth s t a r t s i n the autumn and reaches a peak i n m i d - w i n t e r t o s p r i n g . , The major spawning p e r i o d i s A p r i l b u t spawning may c o n t i n u e i n t o May and June. T o n i c e l l a i n s i g n i s ( F i g . 17) T . . i n s i g n i s d i s p l a y e d a d i s t i n c t l y annual . r e p r o d u c t i v e c y c l e w i t h spawning u s u a l l y c o n f i n e d t o a r e l a t i v e l y s h o r t p e r i o d i n t h e s p r i n g . For example, t h e i n t e r v a l between the l a s t c o l l e c t i o n b e f o r e spawning and t h e f i r s t c o l l e c t i o n a f t e r spawning was o n l y 14 days a t P o r t e a u i n 1973, and a t F i r s t Narrows i t was 18 days i n 1972 and 15 days i n 1973. I t i s l i k e l y t h a t t h e a c t u a l p e r i o d o f spawning was even s h o r t e r than t h e s e c o l l e c t i o n i n t e r v a l s . A l l a n i m a l s c o l l e c t e d b e f o r e spawning had g o n a d a l i n d i c e s of 8.0 o r g r e a t e r , and s h o r t l y a f t e r spawning a l l a n i m a l s had i n d i c e s of 3.0 o r l e s s , w i t h most 2 0 i 52 1 6 f x o •o S 12 f "O c o O 8 0 -P o r t e a u 106 N Tonicel la insignis 11 F i rs t N a r r o w s s 9 H 1 1 1 1 h 1 1 1 1 1 1 1- H 1 1 1-,10 i16 F i r s t N a r r o w s « / 13 6 „. F i r s t N a r r o w s 14 13 9 -) 1 1 1 1 1 1——I 1-M J • J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J j A S 1971 I 1972 I 1973 i 1974 F i g . 17. Hean gonadal index and 95% confidence l i m i t s f o r T o n i c e l l a in s i t j n i s at F i r s t Narrows and Porteau. Porteau F i r s t Marrows Eagle Harbour J F M A M J J A S O N D 1971 1972 1973 1972 1973 1974 1973 Tonicella inslflnls _J present study J I L F i g . 18. Summary of spawning observations on T o n i c e l l a i n s i g n i s : symbols defined i n Figure <». 53 i n d i v i d u a l s c o n t a i n i n g no t r a c e o f gametes. .. The e x a c t t i m e of spawning v a r i e d i n 1972 and 1973 but o c c u r r e d a t about t h e same time a t both P o r t e a u and F i r s t Narrows i n any one year. I n 1972 spawning o c c u r r e d sometime a f t e r 7 th May a t P o r t e a u , and between 20th A p r i l — 8 t h May a t F i r s t Narrows., I n 1973 both p o p u l a t i o n s spawned i n t h e f i r s t week o f A p r i l . I n 1974 c o l l e c t i o n s were o n l y made a t F i r s t Narrows. , In marked c o n t r a s t t o t h e a b r u p t spawnings i n 1972 and 1973, t h e spawning p e r i o d i n 1974 was p o o r l y d e f i n e d , A d e c r e a s e i n t h e mean go n a d a l i n d e x o c c u r r e d d u r i n g A p r i l but spawning was not completed i n A p r i l . F o r t y p e r c e n t o f t h e a n i m a l s c o l l e c t e d on 7t h A p r i l had l a r g e mature gonads., As i n M o g a l i a c i l i a t a , M o g a l i a l a e v i o r and T o n i c e l l a l i n e a t a , t h i s p r o b a b l y r e p r e s e n t s s a m p l i n g e r r o r due t o v a r y i n g degrees o f spawning - a c t i v i t y i n s l i g h t l y d i f f e r e n t l o c a t i o n s a t F i r s t Narrows. Two t o f o u r a n i m a l s w i t h r i p e gonads were found i n each o f tne c o l l e c t i o n s from l a t e May t h r o u g h J u l y . I n September no anxmais c o n t a i n e d mature gametes and unpigmented o o c y t e s were seen i n t h e f e m a l e s . Two c o l l e c t i o n s of T.., i n s i g n i s were made a t Eagle Harbour d u r i n g t h e 1973 spawning p e r i o d . The mean gonadal i n d e x (of a d u l t a n i m a l s , w e i g h i n g 2 g or g r e a t e r ) dropped from 10.3±1.5 (n=8) on 23rd March t o 3.8±1.3 (n=16) on 4th A p r i l . On the l a t e r d a t e few a n i m a l s were y e t i n spen t c o n d i t i o n . There a r e no spawning d a t a on T o n i c e l l a i n s i f l n i s i n t h e l i t e r a t u r e . F i g u r e 18 summarizes t h e r e s u l t s of t h e p r e s e n t s t u d y . I t i s c l e a r t h a t t h i s s p e c i e s has a d i s t i n c t a n n u a l c y c l e w i t h g o n a d a l growth b e g i n n i n g i n e a r l y summer and u s u a l l y 54 an a b r u p t s p r i n g spawning. S t r o n g y j - o c e u t r o t u s d r o e b a c h i e n s i s ( P i g . 19) Most of t h e o b s e r v a t i o n s on S. d r o e b a c h i e n s i s - were made on a s u b l i t t o r a l p o p u l a t i o n a t F i r s t Narrows. I n 1971 t h e r e was an ab r u p t and complete spawning d u r i n g t h e p e r i o d 23rd March-20th A p r i l . , T h i s was f o l l o w e d by a l o n g p e r i o d o f g o n a d a l growth u n t i l a peak was r e a c h e d i n March 1972. Another a b r u p t spawning f o l l o w e d , b u t a few weeks l a t e r t han i n 1971. On 20th A p r i l o n l y 1 s p e n t a n i m a l was c o l l e c t e d , and on 8th May o n l y 1 a n i m a l had n o t completed spawning. Gonadal growth i a the summer of 1972 was s l i g h t compared to t h a t i n t h e summer of the p r e v i o u s y e a r , but more r a p i d growth f o l l o w e d i n the autumn and w i n t e r . I n 1973 spawning a g a i n o c c u r r e d i n e a r l y A p r _ l . ,.• The mean go n a d a l i n d e x dropped from 23.7 on 30th March t o 2.4 on 14th A p r i l . I n 1974 spawning was l e s s a b r u p t t h a n i n 1972 and 1973, On 10th A p r i l , 2 p a r t l y spawned a n i m a l s were found and none were found on 15th A p r i l . There was a marked d e c r e a s e i n t h e mean gon a d a l i n d e x by 20th A p r i l and a l l a n i m a l s c o l l e c t e d on 24th A p r i l had completed spawning. U n e x p e c t e d l y , some a n i m a l s which had not completed spawning were found on 30th A p r i l , and t h i s must be a r e f l e c t i o n o f " p a t c h i n e s s " i n spawning a c t i v i t y . I n 1973 and 1974 o b s e r v a t i o n s were made on t h e time o f spawning o f S, d r o e b a c h i e n s i s i n t h e low i n t e r t i d a l a t B o t a n i c a l Beach. On 6th A p r i l 1973, 1 a n i m a l i n 10 was s p e n t , and on 4 t h May e v e r y a n i m a l was spe n t . Thus spawning was a t about the same 55 30 25 ST 20 75 15 •o ro c o O 10 S t r o n g y l o c e n t r o t u s d r oebach i en s i s 15 \ Botanical Beach 1 0 S. purpuratus, " / Botanical Beach 10 13 14 15] 20 F i r s t N a r r o w s I*** to S. purpuratus, , / Botanical Beach Botanical Beach 16' M A M J J A S O N D J F M A M J J A S O N D J F M A M J J ' A ' S 'o ' N ' D ' J ' F'M ' A'M ' J ' J ' A ' S ' 1971 I 1972 i 1973 I 1974 F i g . 19. Mean gonadal index and 95% confidence U n i t s f o r §iE2Sailocentrotus droebachiensis at F i r s t Narrows and Botanical Beach, and for Strongylocentrotus £urj>uratus at Botanical Beach. 56 J ' F M 1 1 A M ' J ' J ' A ' S ' O ' N 'D Strongylocentrotus droebachiensis F i r s t Narrows Botanical Beach 1971 1972 1973 1974 1973 1974 = i M 1 = 1 =i present study Bergen, Norway — Rdnnstrom, 1927b Tromso, Norway 1943 1951 . _ H Vasseur, 1951 Drobak, Trondheim & Tromso, Norway Salisbury Cove, Maine _ - — 1 Vasseur, 1952 Harvey, 1956 1965 Tucker & Boolootian (in Boolootian, 1966) Lamoine, Maine 1965 Cocanour & A l l e n , 1967 j- 1966 Portugal Cove, Nfld. Bellevue, Nfld. 1968 | ==1969 1965 —, i Himmelman, 1969 Acreman, 1966 — 1 -1 = 1 H Cape Cod Bay, Mass. & Boothbay, Maine Stephens, 1972 Margaret's Bay, N. S. 1 1 1 1 M i l l e r & Mann, 1973 1 1 1 1 1 1 1 Pig. 20. Sumoary of spanning observations on Strongylocentrotus droebachiensis: symbols defined i n Figure 4. ~ ~ 57 t i m e as a t F i r s t Narrows i n 1973. I n 1974 spawning was n e a r l y completed when the f i r s t c o l l e c t i o n was made on 27th A p r i l . A number of c o l l e c t i o n s o f a c l o s e l y r e l a t e d s e a u r c h i n , S t r o n a y l o c e n t r o t u s purp. u r a t u s , were a l s o made a t B o t a n i c a l Beach from t h e same s i t e where S. d r o e b a c h i e n s i s was c o l l e c t e d . ,. I n 1972 g o n a d a l growth i n t h e autumn c o i n c i d e d w i t h t h a t i n S . . d r o e b a c h i e n s i s , but the spawning p a t t e r n i n 1973 was s t r i k i n g l y d i f f e r e n t . . I n S. fiurguratus t h e r e was a very g r a d u a l spawning over 2-3 months. I t s t a r t e d i n e a r l y Bar eh and was not completed u n t i l e a r l y May. A s i m i l a r slow . spawning may a l s o have o c c u r r e d i n 1974.,, I t was i n p r o g r e s s a t t h e t i m e o f the f i r s t c o l l e c t i o n on 2 7 t h A p r i l , and a l l a n i m a l s were not spent u n t i l June. The p r e s e n t s t u d y , and r e p o r t s by Cocanour and A l l e n (1967) and Himmelman (1969), p r o v i d e i n f o r m a t i o n on r e p r o d u c t i v e a c t i v i t y o f S, d r o e b a c h i e n s i s i n d i f f e r e n t seasons. The gonads were always s m a l l i n t h e l a t e s p r i n g , and gonadal growth s t a r t e d i n t h e summer and reached a peak i n l a t e w i n t e r . Many a u t h o r s have r e p o r t e d the t i m e of spawning o f S. ...droebachiensis ( F i g , 2 0 ) , In agreement w i t h t h e p r e s e n t s t u d y , Stephens (1972) i n d i c a t e d t h a t S, d r o e b a c h i e n s i s spawns a b r u p t l y and t h a t i t s p r e c i s e t i m i n g may v a r y i n d i f f e r e n t y e a r s and l o c a t i o n s . , For example, a t Boothbay Harbor, Maine, spawning was sometimes two weeks e a r l i e r t h a n a t Cape Cod, M a s s a c h u s e t t s . ;, In Nova S c o t i a , M i l l e r and Mann (1973) i n d i c a t e d t h a t an e a r l i e r spawning p e r i o d may have o c c u r r e d i n November. T h i s was a p p a r e n t l y based on the appearance of a n i m a l s w i t h l a r g e r i p e gonads a t t h i s time. 58 However, t h i s can h a r d l y be c o n s i d e r e d as e v i d e n c e t h a t gametes were r e l e a s e d . I n Newfoundland, I found some a n i m a l s w i t h s m a l l ' gonads i n December—January but not i n the p r e v i o u s November (Himmelman, 1969). I t was not c e r t a i n whether spawning o c c u r r e d or whether the s m a l l gonads were c h a r a c t e r i s t i c o f a new c o l l e c t i o n s i t e . I n summary, t h e m a j o r i t y of s p e c i e s i n the p r e s e n t s t u d y have a d i s t i n c t l y a n n u a l r e p r o d u c t i v e c y c l e , , The main spawning p e r i o d i s s p r i n g , u s u a l l y A p r i l , when t h e r e i s an a b r u p t and synchronous spawning i n S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s . T o n i c e l l a l i n e a t a , T o n i c e l l a i n s i g n i s , Mojaalia c i l i a t a and M o p a l i a l a e v i o r . K a t h a r i n a t u n i c a t a sometimes spawns p a r t l y a t t h i s t i m e , but t h e main spawning p e r i o d i s June.,, At F i r s t Narrows spawning i n M o p a l i a h i n d s i i i s e a r l i e r than i n t h e above s p e c i e s . . I n K. t u n i c a t a , M. l a e v i o r , and p o s s i b l y M o p a l i a i l i U d s i i , the gonads a r e ' s m a l l f o r s e v e r a l months f o l l o w i n g spawning and r a p i d g onadal growth o c c u r s i n t h e autumn and w i n t e r . . I n c o n t r a s t , gonadal growth i n T. ., l i n e a , t a , T. i n s i g n i s , M. c i l i a t a and S. d r o e b a c h i e n s i s s t a r t s s h o r t l y a f t e r spawning. The data on Mo£alia l i g n o s a and M o p a l i a muscosa do not i n d i c a t e t h a t t h e r e i s an a n n u a l r e p r o d u c t i v e c y c l e . . Mature a n i m a l s were found i n s e v e r a l seasons o f t h e y e a r , and i n M. l i g n o s a spawning was seen i n l a t e w i n t e r - s p r i n g as w e l l as i n t h e summer. 59 O b s e r v a t i o n s and Ex p e r i m e n t s on Spawning Temperature and Spawning i n t h e F i e l d . I n t h e l i t e r a t u r e t h e r e i s much emphasis on temperature as a cue f o r spawning i n marine i n v e r t e b r a t e s . Orton (1920) s t a t e d t h a t most a n i m a l s breed a t a d e f i n i t e t e m p e r a t u r e , and i m p l i e d t h a t merely r e a c h i n g a c r i t i c a l p h y s i o l o g i c a l t e m p e r a t u r e l e v e l s t i m u l a t e d spawning. ,. T h i s h y p o t h e s i s can now be examined f o r the s p e c i e s i n t h e p r e s e n t s t u d y . f i r s t Narrows., F i g u r e 21. shows t h e b i m o n t h l y mean and s t a n d a r d d e v i a t i o n o f d a i l y t e m p e r a t u r e s o f i n c o m i n g water a t the Vancouver P u b l i c Aquarium d u r i n g t h e p e r i o d March 1971—September 1974. The f o u r y e a r monthly mean v a l u e s , 1971-1974, a r e a l s o shown so t h a t p e r i o d s which were warmer or c o l d e r t h a n normal can e a s i l y be r e c o g n i z e d . Superimposed on th e s e d a t a a r e t h e gon a d a l i n d e x c y c l e s f o r t h e s p e c i e s s t u d i e d a t F i r s t Narrows, S t r o n q y l o c e n t r o t u s dr o e ba. c h i e n s i s and T o n i c e l l a l i n e a t a were the o n l y s p e c i e s s t u d i e d a t F i r s t Narrows i n 1971. The w i n t e r and s p r i n g o f 1971 was t h e c o l d e s t p e r i o d d u r i n g t h e p r e s e n t s t u d y . , I n t h a t year 3. .,droebachiensis spawned i n e a r l y A p r i l when t e m p e r a t u r e s averaged 6.3 °c, and l i n e a t a spawned i n l a t e A p r i l - e a r l y May when t h e t e m p e r a t u r e was over 7 °C. I f a c r i t i c a l t e m p e r a t u r e l e v e l i n d u c e d spawning i n t h e s e s p e c i e s the c r i t i c a l l e v e l must have been c o l d e r f o r S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s t h a n f o r I , l i n e a t a . However, i n the t h r e e f o l l o w i n g y e a r s S. d r o e b a c h i e n s i s and I . l i n e a t a 60 2 4 2 0 -1 6 c . o O 8 : F I R S T N A R R O W S W9 . ^ - M . laevior M . h i n d s i | > ^ M. h i n d s i i ^ 1 M. l a e v i o r H 1 . t M A M J J A S O N D J F M A M J J A 1 9 7 1 I 1 9 7 2 O N D J F M A M J J A I 1 9 7 3 S O N D J F M A M J J A 1 9 7 4 F i g . 21. Mean sea water temperature [± standard deviation) f o r the f i r s t half and second half of each month during March 1971-September 1974 at F i r s t Narrows compared to the four year mean (1971-1974) for the f i r s t half and l a s t h a l f of each month; mean gonadal index values for St£oncjil,oc.entr.otu.s d.r.oe.ba.c.h.ie.n,sis, l o n i c e l l a l i n e a t a , ToQisglla. i c s i s n i s , Hop.a,li§. l a g v i s E * iSojoalia. Sili§.ta., Mo£alia h i n d s i i , and flSfiliia Iignosa superimposed on these data, show the r e l a t i o n s h i p of these c y c l e s to temperature. (To make the l i n e s more v i s i b l e , a number of mean gonadal index values for A p r i l , Hay, and June, 1974, have been s h i f t e d s l i g h t l y . ) 61 20 T 16 + x -o 12 c 03 ru c o CD 8 P O R T E A U T. l ineata M. lignosa / V / \ v / \ > / // / // / -// / * -M . laevior _/ •y*<-l. insignis T. l ineata- / ! . . - • ' " l i -"1 t M. laev ior-*// \ T. insignis-*/ \ i A L M. lignosa \/| K 0 - i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i A M J J A S O N D J . F M A M J J A S O N D J F M A 1971 I 1972 I 1973 Pig. 22. A comparison of the mean gonadal index cycles f o r l o n i c e l l a l i n e a t a , T o n i c e l l a i n s i g n i s , fiopalia. l a e v i o r and Mpj^alia lig_nosa at Porteau during A p r i l 1971-April 1973. I 62 B O T A N I C A L B E A C H 0 -I H - r H 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 H 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1—1 M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J 1970 I 1971 I 1972 I 1973 I 1974 F i g . 23. Mean sea water temperature (± standard deviation) f o r each month at amphitrite Point and Sherringham Point during the period May 1970-July 1974 compared to the f i v e year monthly mean temperature (1970-1974) f or each l o c a t i o n ; mean gonadal i n d i c e s o f Katharina t u n i c a t a , Jonicella. l i n e a t a , flo.Ea.lia. h i f i l i i i , fl2E<=I±a c i l i a t a . Strongylocentjotus d.roeba c h i e f s i s and Strong, y.-l2£e.atrotus £ur£ura.tus superimposed on these data show the r e l a t i o n s h i p of the cycles to temperature. spawned a t about the same t i m e . In t h e s p r i n g of 1972 t h e r e was an a b r u p t and synchronous spawning by S. d r o e b a c h i e n s i s , T. l i n e a t a , T o n i c e l l a i n s i g n i s and Mojaalia l a e v i o r i n l a t e A p r i l . The water t e m p e r a t u r e a t t h i s t i m e had r e a c h e d 7,6 °C and was near t h e mean l a t e A p r i l t e m p e r a t u r e s f o r 1971—1974, The warmest s p r i n g was 1973 and i n t h i s year the above s p e c i e s and M o g a l i a c i l i a t a a g a i n spawned a b r u p t l y and i n s y n c h r o n y , but i n e a r l y A p r i l r a t h e r than l a t e A p r i l . Temperatures a t t h i s t i m e were between 7.4-8.0 °C and were t h u s s i m i l a r t o t e m p e r a t u r e s a t t h e t i m e o f spawning i n 1972., I n 1974 w i n t e r and s p r i n g t e m p e r a t u r e s were a g a i n above the f o u r y e ar mean te m p e r a t u r e s f o r w i n t e r and s p r i n g , but t h e spawning p a t t e r n was s t r i k i n g l y d i f f e r e n t t h a n i n t h e p r e v i o u s y e a r s . F o r most s p e c i e s t h e p e r i o d o f spawning was p o o r l y d e f i n e d . J A major drop i n mean g o n a d a l i n d i c e s o f S. d r o e b a c h i e n s i s , X . . l i n e a t a , !• - i f i s i a i i S * fi».iat©li2£» a Q d a . . c i l i a t a o c c u r r e d i n m i d — A p r i l when t e m p e r a t u r e s were 7.6-8.1 °C, but T. l i n e a t a , T . , i n s i g n i s , S * l a e v i o r and fl. c i l i a t a were not d e p l e t e d o f gametes u n t i l s e v e r a l months l a t e r . M o g a l i a h i n d s i i was o n l y s t u d i e d i n 1973 and 1974 and i n t h e s e y e a r s i t spawned e a r l i e r than t h e above s p e c i e s , d u r i n g the p e r i o d when t e m p e r a t u r e s were j u s t s t a r t i n g t o r i s e . The s c a n t y data on M o g a l i a I i g n o s a s uggest t h a t t h e r e may have been w i n t e r as w e l l as spring—summer spawning, which would i m p l y t h a t a c r i t i c a l t e m p e r a t u r e was n o t i m p o r t a n t f o r t h i s s p e c i e s . Thus, t h e h y p o t h e s i s t h a t a g i v e n temperature l e v e l a c t s as a cue f o r spawning would account f o r t h e d e l a y e d spawning which was o b s e r v e d i n most s p e c i e s i n 1972 compared t o 1973, and f o r 64 t h e d e l a y e d spawning of f . l i n e a t a i n 1.971.., A l s o t h e major drop i n g onadal i n d i c e s i n 1974 o c c u r r e d at about • t h e same tem p e r a t u r e as i n t h e p r e c e e d i n g y e a r s , namely 7.6 °C. On t h e b a s i s o f the e a r l i e r spawning t i m e i n H. h i n d s i i , presumably t h i s s p e c i e s would have a lower t e m p e r a t u r e t h r e s h o l d f o r spawning., The data were i n c o n s i s t e n t f o r S. d r o e b a c h i e n s i s . s i n c e i t spawned a t a c o l d e r t e m p e r a t u r e i n 1970 t h a n i n t h e f o l l o w i n g y e a r s . The temperature h y p o t h e s i s would not account f o r the g r a d u a l spawning which o c c u r r e d i n most s p e c i e s i n 1974, compared t o t h e a b r u p t spawning i n the p r e v i o u s y e a r s . I t may be t h a t an i n c r e a s e i n t h e r a t e of warming, r a t h e r than a p a r t i c u l a r t e m p e r a t u r e l e v e l , i n d u c e d spawning. I n 1971 when T. ,.lineata spawned t e m p e r a t u r e s were i n c r e a s i n g a t an a c c e l e r a t e d r a t e compared t o t h e prespawning p e r i o d , but i n S . . d r o e b a c h i e n s i s spawning o c c u r r e d b e f o r e the a c c e l e r a t i o n i n th e r a t e of warming began. There was an i n c r e a s e i n t h e r a t e of warming when most s p e c i e s spawned i n 1972, 1973 and 1974. P o r t e a u ^ Temperature measurements were made a t S t a t i o n s 5 and 6 i n the v i c i n i t y o f P o r t e a u ( F i g . 1) d u r i n g F e b r u a r y — A p r i l by Dr John S t o c k n e r , P a c i f i c E n v i r o n m e n t a l I n s t i t u t e . There was an i n c r e a s e of 1.4 °C o r l e s s a t depths of 2-10 m d u r i n g t h e p e r i o d 2 7 t h F e b r u a r y - 4 t h A p r i l , and a f a s t e r r a t e of warming o c c u r r e d between 4-24th A p r i l . A thermograph p l a c e d a t 8 m below MLIS i n t h e c o l l e c t i o n s i t e a t P o r t e a u showed a r i s e of 0.8 °C between 27th March-IOth A p r i l 1973, and i t was d u r i n g t h i s p e r i o d t h a t t h e r e was an a b r u p t spawning by I . l i n e a t a , S« i S S i a i i 3 . a Q d JH. l a e v i o r ( F i g . 22) . Temperatures were 7.5—8.3 65 °C when t h i s spawning took p l a c e . I f a c r i t i c a l t e m p e r a t u r e s t i m u l a t e d t h i s a b r u p t spawning, t h e re s p o n s e t o t h i s s t i m u l u s must be very s e n s i t i v e i n d e e d . B o t a n i c a l Beach,. F i g u r e 23 shows t h e mean monthly t e m p e r a t u r e s c a l c u l a t e d from d a i l y s u r f a c e t e m p e r a t u r e s f o r t h e p e r i o d May 1970-July 1974, and the f i v e y e a r mean f o r each month of the year (1970-1974) a t both Sherringham P o i n t and A m p h i t r i t e P o i n t l i g h t h o u s e s . , The mean gona d a l i n d e x v a l u e s f o r a n i m a l s a t B o t a n i c a l Beach a r e superimposed on the s e d a t a . E x c e p t f o r l°£alia muscosa, t h e a n i m a l s a t B o t a n i c a l Beach were c o l l e c t e d from 0-1.5 m above MLWS, and Green (1967) c a l c u l a t e d t h a t a n i m a l s from t h i s r e g i o n o f t h e s h o r e a t B o t a n i c a l Beach a r e submerged more than 801 of the t i m e . , Hedgpeth and Gonor (1969) s t r e s s e d t h a t c o r r e l a t i o n s between s u r f a c e t e m p e r a t u r e measurements and b i o l o g i c a l a c t i v i t i e s i n i n t e r t i d a l a n i m a l s a r e not • v e r y r e l i a b l e , s i n c e t h e a c t u a l t e m p e r a t u r e s t o which t h e a n i m a l s a r e exposed v a r i e s g r e a t l y depending on t h e e x a c t l o c a t i o n o f the a n i m a l s on the s h o r e . N e v e r t h e l e s s , t h e r e a r e some s t r i k i n g d i f f e r e n c e s i n r e p r o d u c t i v e a c t i v i t y of a n i m a l s a t B o t a n i c a l Beach i n d i f f e r e n t y e a r s which d i d not appear t o be r e l a t e d t o t e m p e r a t u r e . , I n 1970, K. t u n i c a t a spawned i n e a r l y June when the water temperature was 9 °C o r warmer.,,. I n 1971, K. t u n i c a t a a g a i n spawned i n June and when a s i m i l a r t e m p e r a t u r e was reached. I n 1971 T o n i c e l l a - l i n e a t a spawned i n synchrony w i t h K. t u n i c a t a . I t s h o u l d a l s o be noted t h a t K . : t u n i c a t a spawned a t about t h e same time a t P o i n t No P o i n t , and t h a t spawning by K. t u n i c a t a was completed a t about t h e same t i m e ( l a t e June) a t Frank I s l a n d and A m p h i t r i t e P o i n t a s a t B o t a n i c a l 66 Beach and P o i n t Ho P o i n t . I t i s known t h a t t e m p e r a t u r e s t e n d t o decrease going from A m p h i t r i t e P o i n t t o Sherringham P o i n t due t o m i x i n g w i t h deeper water i n t h e Juan de Fuca S t r a i t . . I n 1972, w i n t e r and s p r i n g t e m p e r a t u r e s were w e l l below the mean f o r 1970-1974, but spawning a t B o t a n i c a l Beach o c c u r r e d e a r l i e r t han i n t h e p r e v i o u s y e a r s and p r o b a b l y b e f o r e t e m p e r a t u r e s reached 8 °C. I n l a t e M a r c h - A p r i l 1972, t h e r e was a complete spawning o c c u r r e d i n T , , l i n e a t a and a p a r t i a l spawning i n K . . t u n i c a t a . S p r i n g t e m p e r a t u r e s i n 1973 were above normal but a g a i n a major spawning o c c u r r e d i n A p r i l when t h e t e m p e r a t u r e was a p p r o x i m a t e l y 9 °C., At t h i s t i m e S t r o n g y l o c e n t r o t u s droebach-i e n s i s and M o g a l i a h i n d s i i spawned c o m p l e t e l y and t h e r e was a p a r t i a l spawning i n T. l i n e a t a and K. t u n i c a t a . , I n 1974, I o n l y observed the l a t t e r p a r t of the spawning p e r i o d but spawning o c c u r r e d when t e m p e r a t u r e s were about 8 °C., I n c o n t r a s t t o the above s p e c i e s , spawning i n S t r o n g y l o c e n t r o t u s p u r g u r a t u s i n 1973 was a slow p r o c e s s , s t a r t i n g when tempe r a t u r e s were near t h e a n n u a l minimum of 7.0-7.5 °C and c o n t i n u i n g u n t i l t h ey r e a c h e d 9.0 °C. Thus a t B o t a n i c a l Beach spawning d i d not appear to be c o r r e l a t e d w i t h a p a r t i c u l a r t e m p e r a t u r e . In t h e c o l d e s t y e a r , 1972, spawning by K. t u n i c a t a and T. l i n e a t a o c c u r r e d e a r l i e r o r as e a r l y as i n the o t h e r y e a r s and a t a lower t e m p e r a t u r e , l e s s t han 8 °C. I n 1970 and 1971 spawning was l a t e , when t e m p e r a t u r e s were above 9 °C, and i n 1973 and 1974 t h e r e was spawning i n A p r i l when tempe r a t u r e s were a p p r o a c h i n g 9 °C. I n summary, a t F i r s t Narrows, T. . l i n e a t a , I . . i n s i g n i s , M. l a e v i o r and M. c i l i a t a spawn when t h e water i s 7-8 °C. S. d r o e b a c h i e n s i s u s u a l l y spawns at t h i s t e m p e r a t u r e b u t 67 sometimes spawns a t a l o w e r t e m p e r a t u r e . M. h i n d s i i spawns near the a n n u a l minimum o r when t e m p e r a t u r e s a r e b e g i n n i n g t o i n c r e a s e . I n c o n t r a s t , a t B o t a n i c a l Beach t h e r e i s no c o n s i s t e n t r e l a t i o n s h i p between spawning and temperature i n S« d r o e b a c h i e n s i s , T. l i n e a t a , K. t u n i c a t a and M. h i n d s i i , e x c e p t t h a t t h e t e m p e r a t u r e i s always above 8 °C. S. p u r p u r a t u s has a p r o l o n g e d spawning p e r i o d and t h e r e f o r e does not appear t o be i n d u c e d by a c r i t i c a l t e m p e r a t u r e . The E f f e c t o f Temperature and L i g h t on Spawning i n t h e L a b o r a t o r y , S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s . , The a n i m a l s m a i n t a i n e d under the v a r i o u s l i g h t and t e m p e r a t u r e regimes showed no i n d i c a t i o n o f spawning a t the t i m e i t o c c u r r e d i n the f i e l d ( F i g . 24). I t i s n o t a b l e t h a t on t h e two o c c a s i o n s when the c o o l i n g system f a i l e d (on 6 t h and 10th A p r i l ) t h e t e m p e r a t u r e i n c r e a s e d about 5 °C i n 2 h i n a l l f o u r e x p e r i m e n t a l t a n k s , but no spawning r e s u l t e d . The g o n a d a l i n d i c e s o f a n i m a l s i n t h e l i g h t - w a r m , l i g h t - c o l d and d a r k - c o l d t a n k s remained h i g h from t h e s t a r t of t h e e x p e r i m e n t s on 30th March u n t i l t h e e x p e r i m e n t s were t e r m i n a t e d on 29th A p r i l , but t h e r e was a f a l l i n t h e i n d e x f o r a n i m a l s i n t h e dark-warm t a n k , , The l a t t e r was due t o spawning which s t a r t e d on 23rd A p r i l , when an a i r b u b b l e r was i n a d v e r t e n t l y t u r n e d on " h i g h " f o r a few hours c a u s i n g a g r e a t d e a l o f a g i t a t i o n . I n an a d d i t i o n a l e x p e r i m e n t , 9 a n i m a l s from the l i g h t - c o l d tank were t r a n s f e r r e d t o a w i r e cage a t below low t i d e l e v e l a t F i r s t Narrows on A p r i l 14., When t h e s e a n i m a l s 68 C ~o co c o 30 20 10 0 DC LW Stronqylocentrotus  droebachiensis group moved to field from April 1 9 - 2 8 1 0 field (First Narrows) — i i March Apr i l May F i g . 24. Bean gonadal index and 95% confidence l i a i t s f o r Strongylocentrotus droebachiensis at F i r s t Narrows during March—May 1973, for groups of animals transferred to four l i g h t and temperature regimes i n the laboratory, and for one group which was transferred to F i r s t Narrows on 19th A p r i l : Dl (dark-warm), DC (dark-cold, LH (light-warm) and LC (light-cold) are laboratory conditions described i n the text. I 69 30 9 c? 20 CO T> CO c o CD 10 0 14 13 15 20, March 181 S . 5 ° C — ~ " 5 .5°C 13 16 1 ^ Strongvlocentrotus droebachiensis 1974 15 laboratory 13 r < field (First Narrows) 8 M F i g . 25. Mean gonadal index and 95% confidence l i m i t s f o r Strongylocentrotus droebachiensis at F i r s t Narrows from March-September 1974, and for groups transferred to various temperature regimes i n the laboratory. 70 were r e t r i e v e d on 28th A p r i l a l l had s m a l l d e p l e t e d gonads, and t h e i r mean gona d a l i n d e x was s i g n i f i c a n t l y s m a l l e r (P<0.01)* than f o r a n i m a l s i n t h e l i g h t - c o l d tank on 29th A p r i l ( F i g . 2 4 ) . I n 1974, S. d r o e b a c h i e n s i s c o l l e c t e d on 12th March and 4 t h A p r i l and k e p t a t 5.5 °C i n the l a b o r a t o r y u n t i l 12th June, and a n i m a l s c o l l e c t e d on 10th A p r i l and kept a t 10.5 C u n t i l 2 1 s t May, showed l i t t l e change i n g o n a d a l i n d i c e s ( F i g . ,25)., T o n i c e l l a l i n e a t a . The e x p e r i m e n t s on T. , , l i n e a t a y i e l d e d r e s u l t s s i m i l a r t o t h o s e f o r S. d r o e b a c h i e n s i s . I n 1973 t h e r e was no spawning i n e x p e r i m e n t a l t a n k s a t t h e time o f spawning i n the f i e l d , b u t some spawning d i d o c c u r i n t h e dark-warm t a n k , p r o b a b l y s t a r t i n g on 23rd A p r i l when S. d r o e b a c h i e n s i s i n t h e same tan k s t a r t e d t o spawn { F i g . 4 ) . Two groups o f a n i m a l s were c o l l e c t e d a t F i r s t Narrows on 14th A p r i l , midway t h r o u g h t h e n a t u r a l spawning p e r i o d , and were m a i n t a i n e d i n two 10 1 c o n t a i n e r s w i t h an incoming s u p p l y o f water a t 5.5 °C and 14.0 °C r e s p e c t i v e l y ; t h e r e was no e v i d e n c e t h a t spawning c o n t i n u e d . On 30th A p r i l t he mean gonadal i n d e x o f t h e s e groups was s i m i l a r to t h e v a l u e f o r 14th A p r i l , when they were c o l l e c t e d , and l a r g e r than t h e f i e l d a n i m a l s on 28th A p r i l , a l t h o u g h s i g n i f i c a n t l y l a r g e r (P<0.05) o n l y f o r the group a t 5.5 °C. S i m i l a r l y , a n i m a l s c o l l e c t e d p r i o r t o spawning i n 1974 and m a i n t a i n e d i n t h e l a b o r a t o r y a t 5.5 °C o r 10,5 °C d i d not spawn ( F i g . 27), On 15th A p r i l , 1974, 15 a n i m a l s , which were •Throughout t h i s t h e s i s when two groups were compared s t a t i s t i c a l l y , a r c s i n t r a n s f o r m a t i o n s were made of gona d a l i n d e x v a l u e s , f o l l o w e d by a t - t e s t . 71 20 x -8 16 c CO "8- 12 c O O 8 0 13 DW D C 10T10 Tonicella lineata 1973 March laboratory 14 field (First Narrows) Apri l May F i g . 26. Mean gonadal index and 9555 confidence l i m i t s f o r To n i c e l l a l i n e a t a at F i r s t Narrows from March—May 1973, and f o r groups transferred to various l i g h t and temperature regimes i n the laboratory. 72 20 x 16 <D "D C .g 12 co c o O 8 0 Tonicella lineata 1974 group moved to / field f r om Apr i l ^ 1 5 - 3 0 field (F i rs t Na r rows ) March A M F i g . 27. Mean gonadal index and 95% confidence l i m i t s f o r I s a i s e i i l i i a e a t a at F i r s t Narrows during March-September 1974, and for groups placed i n various temperature regimes i n the laboratory, and for one group transferred to F i r s t Narrows on 15th A p r i l . 73 o r i g i n a l l y c o l l e c t e d on March 12 and had been kept a t 5.5 °C i n the l a b o r a t o r y , were r e t u r n e d t o F i r s t Narrows where they were kep t i n a p l a s t i c c o n t a i n e r p e r f o r a t e d w i t h h o l e s , , At t h e same ti m e a c o n t r o l group was t r a n s f e r r e d t o 10.5 °C i n t h e l a b o r a t o r y , 1 °C warmer than t h e temperature i n the f i e l d . On 30th A p r i l t he mean gona d a l i n d e x o f t h e group i n the f i e l d was 9.5/ s i m i l a r t o t h e v a l u e f o r t h e n a t u r a l p o p u l a t i o n ( F i g . 2 7 ) . The c o n t r o l group had a mean gona d a l i n d e x of 15.3 on 2 1 s t May, c l o s e t o the v a l u e f o r 12th March when t h e s e a n i m a l s were c o l l e c t e d , a l t h o u g h not s i g n i f i c a n t l y l a r g e r (P<0.05) than the group t r a n s f e r r e d t o t h e f i e l d . I n summary, i n 1973 and 1974 S. d r o e b a c h i e n s i s - and l i f i e a t a were c o l l e c t e d p r i o r t o spawning and m a i n t a i n e d i n the l a b o r a t o r y under v a r i o u s l i g h t and temp e r a t u r e c o n d i t i o n s . Spawning d i d not o c c u r i n t h e s e a n i m a l s when spawning o c c u r r e d i n t h e f i e l d a n i m a l s , , When groups o f unspawned a n i m a l s were r e t u r n e d t o t h e f i e l d t h e i r gonads d e c r e a s e d i n s i z e and became s i m i l a r t o t h e f i e l d a n i m a l s . , Some c o n d i t i o n i n t h e . f i e l d , which was not p r e s e n t i n t h e l a b o r a t o r y , a p p a r e n t l y s t i m u l a t e d spawning, and t h i s f a c t o r d i d not appear to be l i g h t o r tem p e r a t u r e . 74 P h y t o p l a n k t o n O b s e r v a t i o n s i n the F i e l d , Measurements of t h e abundance and s p e c i e s c o m p o s i t i o n of ph y t o p l a n k t o n were made a t s i x s t a t i o n s i n Howe Sound and one i n I n d i a n Arm d u r i n g 1973 by Dr John S t o c k n e r , P a c i f i c E n v i r o n m e n t a l I n s t i t u t e . I n 1973 t h e s p r i n g p h y t o p l a n k t o n bloom de v e l o p e d r a p i d l y i n e a r l y A p r i l . C h l o r o p h y l l a- measurements were l e s s t h a n 1 mg/m3 u n t i l t h e end of March, b u t h i g h v a l u e s were r e c o r d e d i n the f i r s t week o f A p r i l ( F i g . 28). At s t a t i o n s 1 and 2, about 20 km from F i r s t Narrows ( F i g . 1 ) , v a l u e s o f 8.9—9.3 ffig c h l o r o p h y l l a/m3 were r e c o r d e d on 6xh A p r i l , and a t S t a t i o n 6, 2 km from P o r t e a u , t h e r e was 5.0 mg/m3 on 4 t h A p r i l . , T h i s p h y t o p l a n k t o n o u t b u r s t c o i n c i d e d w i t h spawning i n most o f the s p e c i e s s t u d i e d . , At F i r s t Narrows t h e r e was a complete spawning of I . l i n e a t a , T. i f i s i g n i s , S. . d r o e b a c h i e n s i s , M. l a e v i o r and M . . c i l i a t a between 30th March and 14-17th A p r i l , and a t P o r t e a u T. l i n e a t a , T. i n s i g n i s and M. l a e v i o r spawned c o m p l e t e l y between 27th March and 10th A p r i l . , The synchrony between the o n s e t o f t h e p h y t o p l a n k t o n bloom and t h e r e l e a s e o f gametes i n S. , d r o e b a c h i e n s i s and t h e two T o n i c e l l a s p e c i e s s u g g e s t s t h a t some f a c t o r a s s o c i a t e d w i t h t he presence of p h y t o p l a n k t o n was t h e cue f o r spawning., Data on the abundance of t h e more common s p e c i e s o f p h y t o p l a n k t o n found d u r i n g t h e bloom a t S t a t i o n s 1, 2, and 6, compared t o t h e i r abundance b e f o r e t h e bloom, are shown i n Table I I . , T h a l a s s i -o s i r a s p. (T, p a c i f i c a Gran & Angst and/or T. n o r d e a s k i o e l d i i C leve) was ab s e n t o r i n s m a l l g u a n t i t i e s b e f o r e the bloom and dominant d u r i n g t h e bloom, w i t h d e n s i t i e s of 36 9-586 m i l l i o n 75 February M A M J F i g . 28.* Phytoplankton abundance as measured by chlorophyll a for s i x stations i n Hove Sound and one in Indian Arm during February—June 1973 (Dr John Stockner, pers. comm.): each value i s the mean of f i v e measurements made at 0—5 m; mean gonadal index values for Strongylocentrotus droebachiensis. T o n i c e l l a l i n e a t a , and T o n i c e l l a i n s i g n i s , superimposed on these data, show the synchrony of spawning with the phytoplankton bloom i n 1973. 76 February M A M J F i g . 29. Phytoplankton abundance measured by chlorophyll a f o r Stations i n the v i c i n i t y of F i r s t Narrows during February—June 1974: values f o r Stations 1, 2 and 11 represent the mean of three measurements from 1—5 m (Dr John Stockner, pers. comm.) and values for F i r s t Narrows and Jericho Beach are single measurements taken near the surface: mean gonadal indices f o r Strongylocentrotus droebachiensis. Tonicella l i n e a t a . and Ton i c e l l a i n s i g n i s . superimposed on these data, show the prolonged spawning period corresponding to the delayed and slow growth of phytoplankton i n 1974. 77 Table I I . Density (millions of cells/m 3) of common species of phytoplankton at Stations 1, 2 and 6 before and during the blooa i n 1973. (Dr John Stockner, pers. comm.) Station 1973 27th Feb.-6lh Mar. 2nd-6th April Bacillariophyccae Thalassiosira sp. 1 0.0 398 2 11.8 369 6 0.0 586 Skeletonema costatum 1 16.5 13.4 2 11.0 7.06 6 0.0 7.85 Nilzschia seriata 1 2.35 11.8 2 0.78 0.0 6 0.0 3.14 Nacicula sp. 1 0.0 0.0 2 1.57 6.29 6 6.28 4.71 Dinophyceae Gymnodimium sp. 1 0.0 7.85 2 0.0 3.92 6 0.0 1.57 Phytoflagellates 1 0.0 15.7 2 91.2 12.6 3 0.0 33.0 Table I I I . Density (millions of cells/m 3) of Tha l a s s i o s i r a sp. and Skeletonema costatum at Stations 1 and 2 from 6th Harch to 3rd May 1974 (Dr John Stockner, pers. comm.). Station 6th March 1974 2nd April 3rd May Bacillariophyceae Thalassiosira sp. 1 0.0 2.94 530 2 0.0 8.82 1070 Skeletonema costatum 1 32.3 84.3 6210 2 13.7 42.1 12100 78 c e l l s / l a 3 . There was l i t t l e change i n t h e g u a n t i t y of Ske l e t c i -nema costatum (Grev.) C l e v e , M i t z s c h i a s e r i a t a • C l e v e , S a i i s a i a SP« and p h y t o f l a g e l l a t e s b e f o r e and d u r i n g t h e bloom. J S i l S S d i n i u m sp. : was not found b e f o r e the bloom and was i n s m a l l g u a n t i t i e s d u r i n g t h e bloom. I n 1974 t h e s p r i n g p h y t o p l a n k t o n bloom d i d not d e v e l o p as e a r l y o r as r a p i d l y as i n 1973. .. F i g u r e 29 shows c h l o r o p h y l l a measurements f o r f i v e S t a t i o n s i n t h e v i c i n i t y of F i r s t Narrows d u r i n g t h e p e r i o d when spawning o c c u r r e d . There was l e s s than 1 mg c h l o r o p h y l l a/m3 a t a l l S t a t i o n s u n t i l t he end of A p r i l . At J e r i c h o Beach, n e t p l a n k t o n c o u l d not be c o l l e c t e d u n t i l A p r i l 29 when a v a l u e o f 6.2 mg c h l o r o p h y l l a/m3 was found; and a t S t a t i o n s 1 and 2, v a l u e s o f 4.0 and 5.8 mg/m3 were found on May 3. Samples c o l l e c t e d a t t h e s u r f a c e a t F i r s t . N a r r o w s o n l y approached 1.0 mg/m3 from l a t e A p r i l t h r o u g h May. The low v a l u e s i n t h i s a rea may have been due t o the mi x i n g e f f e c t o f the s t r o n g t i d a l r a p i d s , and h i g h e r v a l u e s may have o c c u r r e d d u r i n g o t h e r p a r t s o f the t i d a l c y c l e . I t i s c l e a r t h a t t h e r e was no sh a r p i n c r e a s e i n p h y t o p l a n k t o n i n 1974 compared t o t h a t i n 1973, and t h e s e e v e n t s c o r r e s p o n d w e l l t o t h e d e l a y e d and p o o r l y d e f i n e d spawning i n S. . d r o e b a c h i e n s i s , I , l i n e a t a , i J B s i a n i s , M. l a e v i o r , and M. c i l i a t a - i n 1974. At S t a t i o n s 1 and 2 the d e n s i t y o f T h a l a s s i o s i r a sp. was low on 2nd A p r i l but h i g h on 3rd May, when i t s d e n s i t y was second t o t h a t o f S k e l e t o -nema co s t a t u m (Table I I I ) . I n f o r m a t i o n on t h e s p r i n g p h y t o p l a n k t o n bloom i n 1973 was a l s o c o l l e c t e d by Mr J a e Shim, I n s t i t u t e of Oceanography 79 Table IV. Density (millions of cells/m 3) of diatoms at Stations A and B in the S t r a i t of Georgia, and f o r Station C i n Juan de Fuca S t r a i t , during winter and spring 1973 (Mr Jae Shia, pers. comm.) ... Station Depth 17th January 13-14th February 13-14th March 17th A p r i l 15-16th May 17th June 19th J u l y lm 25m 3.0 0.6 32.9 32.0 2.7 3.0 1570 710 25.8 10.3 3580 1.6 2.0 0.8 lm 25m 6.3 11.4 10.6 16.6 11.2 0.4 2730 146 125 3.6 23.8 0.4 57.7 14.7 lm 25m 1.6 18.2 6.7 7.9 8.8 18.6 109 37.9 72.0 29.3 134 12.5 78.3 185 80 Table V. Density (millions of cells/m 3) of diatom species at Stations A, B, and C before and during the bloom i n 1973 (Mr Jae Shim, pers. comm.) 1973 Station A S t a t i o n B Station C 14th 17th. 13th 17th 14th 17th 16th 17th Depth March A p r i l March A p r i l March A p r i l May June B a c i l l a r io phyc eae Th a l a s s i o s i r a p a c i f i c a lm 0.0 153 0.0 524 0.0 61.0 0.0 0.0 25m 0.0 58.9 0.0 54.6 0.0 33.7 1.9 0.0 Th a l a s s i o s i r a nordenskioeldii lm 0.0 112 0.0 173 0.0 4.7 12.5 0.0 25m 0.0 108 0.0 5.7 0.0 2.0 10.6 1.9 T h a l a s s i o s i r a a e s t i v a l i s lm 0.5 0.0 3.0 0.0 0.0 0.0 5.3 1.3 25m 0.0 . 0.0 0.1 0.0 0.0 . 0.0 3.3 0.7 Th a l a s s i o s i r a eccentricus lm 0.0 2.1 0.0 0.8 0.0 1.3 0.6 0.0 25m 0.0 0.0 0.0 0.0 0.0 10.6 0.0 0.0 Skeletonema costatum lm 0.0 481 0.5 1160 0.0 4.1 1.9 116 25m 0.0 228 0.0 92.2 0.0 8.4 0.0 0.0 Nit z s c h i a d e l i c a t u l a lm 0.1 221 1.4 96.3 0.4 . 7.9 1.9 0.0 25m 0.0 38.0 0.0 9.6 1.0 0.7 7.7 0.0 Nit z s c h i a longissima lm 0.1 12.5 0.0 13.0 0.6 1.3 1.3 0.0 25m 0.0 0.0 0.0 0.0 1.0 1.3 0.2 0.7 Ni t z s c h i a closterium lm 0.0 4.2 0.4 2.3 0.2 0.7 0.0 0.0 25m 0.6 0.0 0.0 0.0 0.2 0.0 0.0 0.0 Corethron criophilum lm 0.0 200 0.0 82.2 0.0 0.7 0.0 0.0 25m 0.0 41.8 0.0 5.7 0.0 0.3 0.0 0.0 Chaetocerus d e b i l i s lm 0.2 247 0.0 357 0.0 2.7 0.0 0.0 25m 0.0 7.7 0.0 0.4 0.0 1.2 0.4 0.0 Thalassionema n i t z s c h i o i d e s lm 0.1 0.7 0.0 5.4 0.1 0.2 1.9 3.3 25m 0.2 1.4 0.1 0.4 0.8 2.7 0.8 3.9 P a r a l i a sulcata lm 0.0 0.0 0.0 0.0 5.4 9.2 12.5 9.2 25m 0.0 0.0 0.0 0.0 11.2 6.8 3.2 2.6 Schroederella d e l i c a t u l a lm 0.4 1.4 0.0 0.0 0.0 0.2 0.0 0.0 25m 0.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 81 0. B. C. (Table I V ) . At s t a t i o n s A and B i n t h e S t r a i t o f G e o r g i a ( F i g . 1) t h e r e was a marked i n c r e a s e i n the abundance o f diatoms from mid-March t o m i d — A p r i l , from 2.7—11.2 t o 1570-2730 m i l l i o n c e l l s / m 3 . T h i s c o i n c i d e d w i t h t h e sharp p h y t o p l a n k t o n i n c r e a s e and spawning o f S. d r o e b a c h i e n s i s , T. l i n e a t a , H« i n s i g n i s , M. l a e v i o r and M. c i l i a t a observed i n e a r l y A p r i l 1973 i n t h e v i c i n i t y o f Vancouver and Howe Sound., At S t a t i o n C i n Juan da Fuca S t r a i t , 36 km from B o t a n i c a l Beach { F i g . 1 ) , t h i s bloom was l e s s i n t e n s e w i t h o n l y a d e n s i t y o f 108 m i l l i o n c e l l s / m 3 found on 17th A p r i l . At B o t a n i c a l Beach M. h i n d s i i and S. d r o e b a c h i e n s i s spawned c o m p l e t e l y i n A p r i l 1973, but K. t u n i c a t a and T, l i n e a t a o n l y spawned p a r t l y . . The l a t t e r two s p e c i e s completed spawning i n June, and t h i s . c o i n c i d e d w i t h a second bloom i n Juan de Fuca S t r a i t (Table I V ) . , The s p e c i e s c o m p o s i t i o n o f diatoms a t S t a t i o n s A, B, and C b e f o r e and d u r i n g t h e bloom i n 1973 i s shown i n T a b l e V, The sharp i n c r e a s e i n T h a l a s s i o s i r a £acifica and T. n o r d e n s k e o l d i i a t S t a t i o n s A and B i n the S t r a i t o f G e o r g i a was comparable t o t h a t observed a t S t a t i o n s 1, 2, and 6 near Howe Sound and B u r r a r d I n l e t (Table I I ) . However, t h e most s t r i k i n g i n c r e a s e a t S t a t i o n s A and B was i n Skeletonema c o s t a t u m , w i t h d e n s i t i e s o f 481-1160 m i l l i o n c e l l s / m 3 r e c o r d e d at 1 m depth on 17th A p r i l . N o t a b l e i n c r e a s e s were a l s o seen i n N i t z s c h i a l o n g i s s i m a (Berb.) H o l f s , C o r e t h r o n c r i o p h i l u m C a s t r a c a n e , and C h a e t o c e r u s d e b i l u s C l e v e . At S t a t i o n C, t h e A p r i l bloom was not heavy, and !• M £ i f i £ a w a s t i i e most common s p e c i e s w i t h 61 m i l l i o n c e l l s / m 3 found a t 1 m depth on 17th A p r i l . Other s p e c i e s which showed a marked i n c r e a s e from March t o A p r i l a t S t a t i o n C were 82 1" n o r d e n s k e o l d i i , and I . e c c e n t r i c u s (Ehr.) C l e v e , and S k e l e t o -nema c o s t a t u m . , D u r i n g the June bloom a t S t a t i o n C, Skeletonema costatum was t h e predominate s p e c i e s , and o t h e r s p e c i e s which were i m p o r t a n t i n the o t h e r blooms were uncommon. I n t h e s e p h y t o p l a n k t o n o b s e r v a t i o n s (Table IV"), Skeletonema costatum showed i n c r e a s e s which most c l o s e l y c o r r e s p o n d e d t o t h e spawning t i m e s of S. ...droebachiensis, T. l i n e a t a , T. i n s i y n i s , M. l a e v i o r , I ' c i l i a t a , and K. ..tunicata a t F i r s t Narrows, P o r t e a u , and B o t a n i c a l Beach. i n both 1973 and 1974 t h e r e was a c l o s e c o r r e l a t i o n between the s p r i n g p h y t o p l a n k t o n o u t b u r s t and spawning i n t h e f i e l d . Temperatures o n l y i n c r e a s e d s l i g h t l y d u r i n g the spawning p e r i o d and t h e r e was no apparent t r e n d i n s a l i n i t y . , These o b s e r v a t i o n s suggest t h a t p h y t o p l a n k t o n i t s e l f , o r some f a c t o r a s s o c i a t e d w i t h the p h y t o p l a n k t o n bloom, s t i m u l a t e d spawning. E f f e c t of P h y t o p l a n k t o n on Spawning i n the L a b o r a t o r y I n 1973, f o l l o w i n g the ob s e r v e d synchrony o f t h e s p r i n g p h y t o p l a n k t o n bloom and spawning i n t h e f i e l d , l a b o r a t o r y e x p e r i m e n t s were conducted to t e s t the h y p o t h e s i s t h a t t h e presence of p h y t o p l a n k t o n would i n d u c e spawning. Groups o f unspawned a n i m a l s , from the t a n k s which were s e t up on 30th March t o t e s t t h e e f f e c t o f l i g h t and t e m p e r a t u r e , were t r e a t e d w i t h n a t u r a l p h y t o p l a n k t o n from J e r i c h o Beach (see Methods). These e x p e r i m e n t s were r u n from 21-27th A p r i l . I n a l l t h r e e t r e a t e d groups spawning s t a r t e d on t h e f i r s t o r second day of 83 th e e x periment and heavy spawning f o l l o w e d . S i n c e t h e r e were not enough a n i m a l s t o e s t a b l i s h p r o p e r c o n t r o l s , the mean gonadal i n d e x of each t r e a t e d group on 2 7 t h A p r i l was compared t o i t s " s o u r c e " tank on 12th A p r i l and 29th A p r i l ( F i g . , 3 0 ) . I n every case t h e a n i m a l s exposed t o p h y t o p l a n k t o n had s i g n i f i c a n t l y s m a l l e r gonads (P<0.01). The r e s u l t s o f the 1974 e x p e r i m e n t s on t h e e f f e c t o f phytoplanktom on spawning are shown i n T a b l e V I , I n e x p e r i m e n t s performed a t 5.5 °C, 62% of the t r e a t e d S t r o n g y l o c e n t r o t u s droe-b a c h i e n s i s from 12th March spawned i n 10 days of p l a n k t o n t r e a t m e n t (Expt. 1) ,compared t o 44S o f t h e a n i m a l s from 4 t h A p r i l (Expt. 2) . At 7.0 °C, 7 out o f 10 a n i m a l s t r e a t e d w i t h sperm spawned (Expt. 3, T a b l e VI) . , At 5.5 °C, 64% o f the T o n i c e l l a l i n e a t a from 12th March spawned i n 10 days o f p l a n k t o n t r e a t m e n t ( E x p t . , 4 ) , compared t o 1% of the a n i m a l s from 4 t h A p r i l (Expt. 5 ) . I n Experiment 6 performed a t 10 °C, a l l 9 a n i m a l s from 12th March spawned, and i n Experiment 7, which was s t a r t e d a few days l a t e r , 67$ o f t h e a n i m a l s from 12th March spawned. I n t h e l a t t e r e x p e r i m e n t 2 o f the t r e a t e d a n i m a l s d i e d and were not counted i n t h e r e s u l t s . The 13 a n i m a l s which d i d not spawn a t 5.5 °C i n Experiment 5 were t r a n s f e r r e d t o 10.0 °C on 15th May, No spawning r e s u l t e d d u r i n g t h e next t h r e e days of warmer c o n d i t i o n s . , From 18-28th May f r o z e n p l a n k t o n was added t o t h e s e a n i m a l s and 9 o u t o f t h e 13 a n i m a l s spawned (Expt. 8 ) . The 7 c o n t r o l a n i m a l s i n t h i s e x periment were a l s o from Experiment 5 and none spawned, but 2 d i e d . , When sperm s u s p e n s i o n was added t o 12 T . . l i n e a t a from 84 30 | 20 "O CO c o CD 10 0 10 14 3. droebachiensis, DC 10 10 I lineata, DC 10 I lineata, LC f \ \ \ J 7 star t of plankton treatments 15 12 H h-21 April 1973 27 29 F i g . 30. Mean gonadal index and 9536 conf i d e n c e l i m i t s f o r groups of S t r o n q y l o c e n t r q t u s d r o e b a c h i e n s i s and T o n i c e l l a l i n e a t a t r e a t e d with phytoplankton from 21-27th A p r i l 1973, compared with events i n tanks from which these groups were taken. Table VI. Effect of natural phytoplankton and sperm suspension on StrongyJ.ocentrotus droebachiensis. T o n i c e l l a l i n e a t a . and To n i c e l l a i n s i g n i s . 1 0 - 7 / 1 Expt no. and date Date Exp. T Total Total % No. of collected (°C) spawned unspawned spawned controls* Strongylocentrotus droebachiensis Plankton treated 1. 3rd-13th May 12th March 5.5 8 5 62 6 2. lst- l l th May 4th April 5.5 4 5 44 5 Sperm treated 3. 30th April-lOth May 12th March 7.0 7 4 64 5 Tonicella lineata Plankton treated 4. 4th-14th May 12th March 5.5 7 4 64 ' 9 5. 6th-16th May 4th April 5.5 1 13 7 7 6. 15th-25th May** 12th March 10.0 9 0 100 8 7. 19th-29th May** 12th March 10.0 4 2 67 8 8. 18th-28th May** 4th April 10.0 9 4 69 7 Sperm treated 9. 4th-14th May 12th March 5.5 8 4 67 9 Tonicella insignis Plankton treated 10. 4th-14thMay 12th March 5.5 12 4 75 7 Sperm treated 11. 6th-16thMay 12th March 5.5 6 3 67 4 * No control animals spawned in any of the experiments. ** Frozen plankton was used after 19th May (see text). 85 12th March, 8 a n i m a l s spawned (Expt. 9, T a b l e V I ) . , A l a r g e r p r o p o r t i o n o f T o n i c e l l a i n s i g n i s spawned a t low t e m p e r a t u r e s than d i d T. l i n e a t a . At 5.5 °C, 12 out o f 16 a n i m a l s spawned w i t h i n s i x days o f p l a n k t o n t r e a t m e n t , and 3 of the unspawned a n i m a l s were l a t e r found t o have undeveloped gonads (Expt. 10). S i x out o f 9 a n i m a l s t r e a t e d w i t h sperm spawned (Expt. 11, T a b l e V I ) . These l a b o r a t o r y e x p e r i m e n t s suggest t h a t the p r e s e n c e of p h y t o p l a n k t o n s t i m u l a t e s spawning i n S. d r o e b a c h i e n s i s , T. l i n e a t a , and T. i n s i g n i s , and t h a t sperm s u s p e n s i o n s a r e a l s o e f f e c t i v e i n i n d u c i n g them t o spawn. 86 DISCUSSION The R e g u l a t i o n o f R e p r o d u c t i v e C y c l e s R e p r o d u c t i v e c y c l e s a r e not 'independent e v e n t s but a r e c o o r d i n a t e d w i t h o t h e r b i o l o g i c a l a c t i v i t i e s , f o r example, i n the u r c h i n , S t r o n g y l o c e n t r o t u s i n t e r m e d i n s , the a n n u a l c y c l e i n g o n a d a l development i s c o o r d i n a t e d w i t h annual c y c l e s i n ' t h e r a t e o f f o o d consumption and o f body growth ( F u j i , 1967). C y c l e s i n t h e l e v e l s of v a r i o u s b i o c h e m i c a l c o n s t i t u e n t s of v a r i o u s body organs are known f o r many i n v e r t e b r a t e s (eg, G i e s e , 1966, 1969) and presumably a r e brought about by m e t a b o l i c s h i f t s , c h anging t h e p r o p o r t i o n of incoming energy (or s t o r e d energy) c h a n n e l e d i n t o s o m a t i c or g o n a d a l growth. I t i s l i k e l y t h a t n e u r o e n d o c r i n e mechanisms, as are known f o r many v e r t e b r a t e s , a r e i m p o r t a n t i n c o o r d i n a t i n g r e p r o d u c t i o n w i t h o t h e r e v e n t s i n i n v e r t e b r a t e s , but t hey a r e not w e l l u n d e r s t o o d . At c e r t a i n p o i n t s i n t h e s e i n t e r n a l p h y s i o l o g i c a l c y c l e s the e x t e r n a l environment may a f f e c t t h e s e i n t e r n a l p r o c e s s e s , t h e r e b y a c t i n g as a cue. Such e x t e r n a l cues may be of p a r t i c u l a r i m p o r t a n c e d u r i n g r e p r o d u c t i v e phases, - s i n c e t h e young must be produced when e n v i r o n m e n t a l c o n d i t i o n s a r e f a v o u r a b l e , and t o e nsure the c o o r d i n a t i o n o f gamete r e l e a s e i n a n i m a l s which spawn. The f a c t t h a t most organisms show some degree o f s e a s o n a l i t y i n t h e i r r e p r o d u c t i v e c y c l e s i n d i c a t e s t h a t they a r e a f f e c t e d by e x t e r n a l f a c t o r s . I n t r y i n g t o e l u c i d a t e e n v i r o n m e n t a l cues s e v e r a l approaches a r e u s e f u l . 87 E x a m i n a t i o n o f r e p r o d u c t i v e c y c l e s i n d i f f e r e n t l o c a t i o n s and i n d i f f e r e n t y e a r s , i f c o u p l e d w i t h good d a t a on the p h y s i c a l and b i o t i c e n vironment, may suggest t h e importance o f some f a c t o r s and make o t h e r s l e s s l i k e l y . I f t h e c y c l e s vary i n d i f f e r e n t l o c a t i o n s , l o c a l f a c t o r s a re p r o b a b l y i m p o r t a n t , whereas i f e v e n t s occur i n synchrony over d i s t i n c t g e o g r a p h i c a l a r e a s , the c y c l e s may be c o n t r o l l e d by some c o n d i t i o n which i s u n i f o r m o v e r w i d e l y s e p a r a t e d a r e a s or may have s t a r t e d a t some d i s t a n t r e f e r e n c e p o i n t and be m a i n t a i n e d i n t e r n a l l y w i t h o u t a d d i t i o n a l e x t e r n a l s t i m u l a t i o n . , In the l a t t e r i n s t a n c e , the rhythm s h o u l d c o n t i n u e i f a n i m a l s a r e brought i n t o t h e l a b o r a t o r y from t h e f i e l d . I t must be emphasized t h a t e n v i r o n m e n t a l f a c t o r s which a r e c l o s e l y c o r r e l a t e d w i t h c e r t a i n r e p r o d u c t i v e e v e n t s can o n l y be c o n s i d e r e d as p o s s i b l e cues. ,, Some e n v i r o n m e n t a l c o n d i t i o n s may be a p r e r e q u i s i t e f o r c e r t a i n e v e n t s , but may not d i r e c t l y i n i t i a t e the p r o c e s s . , E x p e r i m e n t s , p r e f e r a b l y under a wide v a r i e t y o f c o n d i t i o n s , s h o u l d be performed t o t e s t any h y p o t h e t i c a l cue. P o s s i b l e F a c t o r s fiegulating Gonadal Growth The i n t e r p r e t a t i o n o f the r e s u l t s of the p r e s e n t s t u d y i s l i m i t e d by a l a c k o f i n f o r m a t i o n on i n t e r n a l e v e n t s i n the a n i m a l s s t u d i e d . Some gametogenic phases, such as t h e i n i t i a t i o n of gametogenesis o r v i t e l l o g e n e s i s , may be s t i m u l a t e d by e n v i r o n m e n t a l c u e s , but the t i m i n g o f the s e e v e n t s was n o t examined. . 88 Si§£o^gical Events..., Some i n f o r m a t i o n on gametogenesis of the s p e c i e s c o n s i d e r e d i n t h e p r e s e n t study i s a v a i l a b l e from e a r l i e r papers. N i m i t z and Giese (1964) report: t h a t i n K a t h a r i n a t u n i c a t a the a c t i v e p e r i o d o f gametogenesis s t a r t s i n the w i n t e r when t h e gonads a r e growing r a p i d l y , and t h e r e i s e v i d e n c e of n u t r i e n t t r a n s f e r from t h e go n a d a l e p i t h e l i u m (and p o s s i b l y o t h e r body organs) t o t h e d e v e l o p i n g gametes,, They s t a t e t h a t o o g e n e s i s i n K. t u n i c a t a t a k e s two y e a r s , w i t h t h e o o c y t e s r e a c h i n g 35-50 ju i n d i a m e t e r i n t h e f i r s t s e a s o n , and 175 p. i n the second season when t h e y are mature ova. , Anderson (1969) d e s c r i b e s t h e s u b c e l l u l a r d i f f e r e n t i a t i o n o f o o g o n i a i n t o mature ova i n M o p a l i a muscosa, u s i n g a n i m a l s c o l l e c t e d i n t h e w i n t e r . He does not i n d i c a t e t h e p r o p o r t i o n of v a r i o u s s t a g e s found a t t h i s t i m e o f the y e a r , , Barnes (1972) r e p o r t s a d i s t i n c t l y a n n u a l gametogenic c y c l e i n T o n i c e l l a l i n e a t a . I n males, a f t e r spawning the t e s t i c u l a r lumens are empty of sperm and t h e g e r m i n a l l a m e l l a r e p i t h e l i u m i s t h i n , w i t h a r e a s of sperm p r o d u c t i o n b e i n g r a r e . I n t h e summer and autumn the g e r m i n a l l a m e l l a e t h i c k e n and t h e r e i s a g r a d u a l i n c r e a s e i n sperm p r o d u c t i o n a l o n g t h e i r s u r f a c e , , By F e b r u a r y t h e r e i s sperm p r o d u c t i o n a l o n g the e n t i r e l a m e l l a r s u r f a c e and t h e lumens a r e f i l l e d w i t h spermatozoa. The l a m e l l a e become t h i n n e r b e f o r e spawning o c c u r s , i n d i c a t i n g t h a t new s p e r m a t i d s a r e no l o n g e r b e i n g produced. I n f e m a l e s , young o o c y t e s appear j u s t b e f o r e o r soon a f t e r spawning, and e a r l y s t a g e s of o o g e n i s predominate thr o u g h o u t t h e summer. The o o c y t e s e n l a r g e d u r i n g t h e autumn. By J a n u a r y t h e o v a r i a n lumens are b e g i n n i n g t o f i l l w i t h mature ova and e a r l y o o g e n i c s t a g e s a r e uncommon, .,• P r i o r t o 89 spawning t h e lumens are b u l g i n g w i t h mature ova and o t h e r s t a g e s ar e uncommon. I n t h e p r e s e n t s t u d y i t was observed t h a t t h e gonads i n K a t h a r i n a t u n i c a t a , M o p a l i a l a e v i o r and M o p a l i a h i n d s r i u s u a l l y remained s m a l l d u r i n g t h e summer and grew r a p i d l y i n t h e autumn and w i n t e r , whereas i n S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s , T o n i c e l l a l i n e a t a , T o n i c e l l a i n s i g n i s and M o p a l i a c i l i a t a the gonads s t a r t e d growing s h o r t l y a f t e r t h e s p r i n g spawning., The p o s s i b l e r e l a t i o n s h i p between t h e s e o b s e r v e d p a t t e r n s i n gonadal development and t e m p e r a t u r e , p h o t o p e r i o d and n u t r i t i o n w i l l now be examined. Temperature The i n f l u e n c e o f temperature on g o n a d a l development has been s t r e s s e d more th a n any o t h e r f a c t o r . I n some s p e c i e s , f o r example mussels and o y s t e r s ( C l i p p e r f i e l d , 1953; K o r r i n g a , 1957), t h e gonads a r e i n a c t i v e d u r i n g t h e w i n t e r b u t become a c t i v e when t h e t e m p e r a t u r e reaches a c e r t a i n l e v e l i n t h e s p r i n g . I n a v a r i e t y o f i n v e r t e b r a t e s i n c l u d i n g l a m e l l i b r a n c h s , o p i s t h o b r a n c h s , e c h i n o i d s and s h r i m p , which n o r m a l l y r e p r o d u c e i n the s p r i n g or summer, i t has been shown t h a t a n i m a l s can be brought i n t o r i p e c o n d i t i o n i n t h e w i n t e r by e x p o s i n g them t o i n c r e a s e d t e m p e r a t u r e s i n t h e l a b o r a t o r y (Townsend, 1940; l o o s a n o f f £ D a v i s , 1963; Smith & C a r e f o o t , 1967; L i t t l e , 1968)., I n t h e bay s c a l l o p , A e g u i p e c t e n i r r a d i a n s , the i n i t i a t i o n o f gametogenesis r e g u i r e s both an i n c r e a s e i n temperature t o 15—20 90 °C and a s u p p l y o f food ( S a s t r y , 1966, 1968), Once a c e r t a i n amount o f n u t r i e n t s have accumulated t h e c o m p l e t i o n of o o g e n e s i s r e q u i r e s a f u r t h e r i n c r e a s e i n t e m p e r a t u r e to over 20 °C, but a food s u p p l y i s no l o n g e r n e c e s s a r y . , Temperature appears t o a c t d i r e c t l y on t h e gonads of the s c a l l o p , Pecten y e s s o e n s r s , s i n c e i n e x p e r i m e n t s by Yamamoto (1951) a r i s e i n t e m p e r a t u r e caused m a t u r a t i o n o f p r i m a r y o o c y t e s and passage o f t h e eggs i n t o t h e o v i d u c t s i n o v a r i e s which had been removed from the a n i m a l s . Leonard (1969) found t h a t gonadal development s t a r t e d e a r l i e r i n the o y s t e r , O s t r e a e d u l i s , i n a n i m a l s which were t r a n s f e r r e d t o Southern C a l i f o r n i a t h a n i n the p a r e n t a l p o p u l a t i o n i n Maine. The c l a m . Mya a r e n a r i a , on the A t l a n t i c c o a s t o f North A m e r i c a , u s u a l l y has one b r e e d i n g p e r i o d d u r i n g t h e warmer months o f the y e a r , but i n t h e s o u t h e r n p a r t of i t s range t h e r e may be two b r e e d i n g p e r i o d s as a r e s u l t o f an i n t e r r u p t i o n of gametogenesis d u r i n g t h e p e r i o d o f h i g h e s t t e m p e r a t u r e s i n mid-summer (Hopes & S t i c k n e y , 1965; P f i t z e n m e y e r , 1965). , A l s o , Cochran and Engelman (1972) found t h a t S t r o n g y l o c e n t r o t u s £U££urajus i n s o u t h e r n C a l i f o r n i a l o s t i t s a b i l i t y t o produce gametes when t e m p e r a t u r e s r o s e t o 17 °C. Other s p e c i e s r e g u i r e low t e m p e r a t u r e s f o r gonadal development. For example, C r i s p and P a t e l (1969) demonstrated t h a t t h r e e b o r e o — a r c t i c b a r n a c l e s p e c i e s r e g u i r e c o n d i t i o n i n g f o r s e v e r a l weeks below a c e r t a i n t e m p e r a t u r e b e f o r e the gonads w i l l mature. Thus, f o r numerous s p e c i e s i t i s c l e a r t h a t t e m p e r a t u r e i s t h e major s t i m u l u s f o r g o n a d a l development. I n the p r e s e n t s t u d y , g o n a d a l growth of K a t h a r i n a - t u n i c a t a and M o g a l i a l a e v i o r began i n t h e autumn when t e m p e r a t u r e s were 91 d e c l i n i n g ( F i g s . .1.3 & 16). Webber and G i e s e ( 1 9 6 9 ) , from o b s e r v a t i o n s on t h e r e p r o d u c t i v e c y c l e of K. t u n i c a t a o v e r a t e n year p e r i o d i n t h e Monterey a r e a , r e p o r t e d t h a t t h e r e was no c o n s i s t e n t r e l a t i o n s h i p between g o n a d a l growth and t e m p e r a t u r e . I n some y e a r s gonadal growth o c c u r r e d w h i l e t e m p e r a t u r e s were s t e a d i l y d e c l i n i n g , w h i l e i n o t h e r years t e m p e r a t u r e s f l u c t u a t e d , , I n t h e p r e s e n t s t u d y , T o n i c e l l a l i n e a t a , • • T o n i c e l l a i n s i g n i s , M o g a l i a c i l i a t a and S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s s t a r t e d gonadal growth i n June (except when spawning was delayed) and d u r i n g the f i r s t 3—4 months of g o n a d a l growth t e m p e r a t u r e s were i n c r e a s i n g . However, Barnes (1972) observed the same p a t t e r n of gonadal growth i n a p o p u l a t i o n o f T, l i n e a t a i n Oregon where summer te m p e r a t u r e s f l u c t u a t e d due t o u p w e l l i n g . I n a l l of t h e above s p e c i e s the gonads c o n t i n u e d e n l a r g i n g as t e m p e r a t u r e s dropped to the w i n t e r minimum and as warming began i n l a t e w i n t e r and s p r i n g . I t i s p o s s i b l e t h a t d i f f e r e n t gametogenic a c t i v i t i e s a r e s t i m u l a t e d by d i f f e r e n t t e m p e r a t u r e c o n d i t i o n s . , I n B a r n e s 1 (1972) d e s c r i p t i o n of o o g e n e s i s i n T. . . l i n e a t a e a r l y s t a g e s were common i n t h e summer and autumn but not i n January. J a n u a r y through March appeared t o be a p e r i o d when o o c y t e s grew and matured, r a t h e r than a p e r i o d when new o o c y t e s were formed. T h i s change i n gametogenic a c t i v i t y c o u l d be r e l a t e d t o the change from d e c r e a s i n g t o i n c r e a s i n g t e m p e r a t u r e . , Thus, i n T. l i n e a t a and o t h e r s p e c i e s which spawn i n the s p r i n g , a s l i g h t i n c r e a s e i n t e m p e r a t u r e may be r e q u i r e d f o r g o n a d a l m a t u r a t i o n . T h i s would not be t h e case f o r M o g a l i a h i n d s i i - and a n o t h e r c h i t o n . C r y g t o e h i t o n s t e l l e r i , s i n c e i n t h e s e s p e c i e s peak 92 g o n a d a l i n d i c e s and spawning o c c u r i n the c o l d e s t p e r i o d o f the year ( F i g , .5;Tucker & G i e s e , 1962; Lawrence, Lawrence & G i e s e , 1965) P h o t o p e r i o d The h y p o t h e s i s t h a t p h o t o p e r i o d c o n t r o l s gonadal development i n some s p e c i e s seems p l a u s i b l e . The a n n u a l c y c l e i n d a y l e n g t h , the t i m e between s u n r i s e and s u n s e t , becomes i n c r e a s i n g l y pronounced g o i n g from the aguator t o t h e p o l e s . T h i s t r e n d i s even more a c c e n t u a t e d when t h e morning and e v e n i n g t w i l i g h t p e r i o d s are i n c l u d e d i n t h e c a l c u l a t i o n of e f f e c t i v e d a y l e n g t h ( S a d l e i r , 1969). For example, a t 50° l a t i t u d e t h e r e i s a very r a p i d change i n e f f e c t i v e d a y l e n g t h i n J u n e - J u l y and a g a i n i n December-January, w h i l e d u r i n g t h e r e s t of t h e y e a r t h e r e i s n e a r l y a s t e a d y i n c r e a s e o r d e c r e a s e i n d a y l e n g t h . P h o t o p e r i o d c o n t r o l of r e p r o d u c t i o n i s w e l l known i n many v e r t e b r a t e s , and t h e mechanism i n v o l v e s p h o t o r e c e p t o r s and nervous and hormonal pathways ( B u l l o u g h , 1961). The h y p o t h e s i s t h a t p h o t o p e r i o d c o n t r o l s r e p r o d u c t i o n i s a p p e a l i n g i n t h a t i t would account f o r synchrony amongst w i d e l y s e p a r a t e d p o p u l a t i o n s . I n marine i n v e r t e b r a t e s o n l y a few r e s e a r c h e r s have examined the p o s s i b l e c o n t r o l o f r e p r o d u c t i o n i»y p h o t o p e r i o d , and a few o t h e r s have a l l u d e d to t h i s p o s s i b i l i t y , While Barnes (1963) and C r i s p and P a t e l (1969) i n d i c a t e d t h a t d e c r e a s e d t e m p e r a t u r e s a r e the most i m p o r t a n t i n f l u e n c e on g o n a d a l 93 m a t u r a t i o n i n b o r e a l c i r r i p e d e s , t hey a l s o demonstrated t h a t long—day p h o t o p e r i o d s t r o n g l y i n h i b i t e d t h i s p r o c e s s . Gonor (1973) noted t h a t g o n a d a l growth i n s e v e r a l p o p u l a t i o n s o f S t r o n g y l o c e n t r o t u s p u r p u r a t u s i n Oregon d i d not s t a r t u n t i l l a t e June, and gonadal enlargement o c c u r r e d between the summer and w i n t e r s o l s t i c e s ( a l t h o u g h the m a t u r a t i o n phase c o n t i n u e d i n t o t h e w i n t e r ) . B o o l o o t i a n (1963) p e r i o d i c a l l y t o o k b i o p s i e s o f the gonads of t h e same male S t r o n g y l o c ^ e n t r o t u s p u r p u r a t u s and found t h a t under a 14 h l i g h t : 10 h dark p h o t o p e r i o d m a i n l y spermatogonia were produced, but when t h e p h o t o p e r i o d was changed t o 6 h l i g h t : 18 h d a r k , spermatogonia d e c r e a s e d i n numbers and s p e r m a t i d s and spermatozoa were produced. , I n r e c e n t l a b o r a t o r y s t u d i e s on S, p u r p u r a t u s , Cochran and Engelman (1975) r e p o r t e d t h a t t h e o n s e t of r e p r o d u c t i v e a c t i v i t y was not a f f e c t e d by p h o t o p e r i o d . These experiments were co n d u c t e d i n t h e autumn and e a r l y w i n t e r when one would e x p e c t r a p i d g o n a d a l growth t o be o c c u r r i n g c o i n c i d e n t a l w i t h d e c r e a s i n g p h o t o p e r i o d . However, t h e i r e x p e r i m e n t s were p o o r l y designed i n t h a t t h e i r c r i t e r i a f o r t h e onset of r e p r o d u c t i v e a c t i v i t y was the appearance of mature gametes o o z i n g from t h e gonads. They would not have d e t e c t e d a p r o l i f e r a t i o n and development of e a r l i e r s t a g e s by t h i s method, , I n t h e p r e s e n t s t u d y , d u r i n g t h e p e r i o d o f d e c r e a s i n g p h o t o p e r i o d , t h e r e was gonadal growth i n S t r o n g y l o c e n t r o t u s • • d r o e b a c h i e n s i s , T o n i c e l l a l i n e a t a , T o n i c e l l a i n s i g n i s - and Mo p a l i a c i l i a t a , but gonadal growth c o n t i n u e d i n t o t h e w i n t e r and s p r i n g . As d e s c r i b e d e a r l i e r , i n T. l i n e a t a i n Oregon o n l y t h e l a t t e r s t a g e s o f o o g e n e s i s were common a f t e r December 94 (Barnes, 1972), I t i s p o s s i b l e t h a t t h e change from d e c r e a s i n g t o i n c r e a s i n g d a y l e n g t h may have s t i m u l a t e d gonadal m a t u r a t i o n i n t h e s p e c i e s which spawn i n the s p r i n g . For a few marine i n v e r t e b r a t e s t h e r e i s some e v i d e n c e t h a t p h o t o p e r i o d a f f e c t s gonadal development v i a a n e u r o e n d o c r i n e m e c h a n i s m , F o r example, i n Octopus, H e l l s and M a l l s ( 1 9 5 9 ) , and H e l l s (1960) r e p o r t e d t h a t i n October a s e c r e t i o n from the o p t i c g l a n d s t i m u l a t e d g o n a d a l development, and t h e s e c r e t o r y a c t i v i t y o f t h i s g l a n d was i n t u r n c o n t r o l l e d by i n h i b i t o r y n e r v e s from the b r a i n . A l s o , i n some C r u s t a c e a , p r o d u c t i o n of g o n a d o t r o p h i c hormones by the a n d r o g e n i c g l a n d i n males and by the ovary i n f e m a l e s i s i n h i b i t e d by a hormone produced i n the X—organ s i n u s g l a n d system l o c a t e d i n the e y e s t a l k ( A d i y o d i & A d i y o d y , 1970). T h i s organ i n t u r n may be c o n t r o l l e d by the c e n t r a l nervous system. These i n t e r n a l pathways are c o n c e i v a b l y i n f l u e n c e d by p h o t o p e r i o d . Mi H o t t (1966) s u g g e s t e d t h a t i n e c h i a o i d s l i g h t p a s s i n g t h r o u g h the t e s t might s t i m u l a t e t h e gonads d i r e c t l y , o r t h e r e may be an i n t e r m e d i a t e n e u r o e n d o c r i n e pathway., S i m i l a r l y , i n c h i t o n s the gonads l i e d i r e c t l y under the d o r s a l p l a t e s and i n most s p e c i e s l i g h t p a s s i n g through t h e p l a t e s c o u l d a f f e c t the gonads i n some d i r e c t way. A l t e r n a t i v e l y l i g h t c o u l d a f f e c t g o n a d a l development by a n e u r o s e c r e t o r y pathway i n v o l v i n g t h e l i g h t s e n s i n g o r g a n s , t h e a e s t h e t e s , which are l o c a t e d i n the p l a t e s . 95 N u t r i t i o n L arge q u a n t i t i e s o f n u t r i e n t s a r e r e q u i r e d f o r gon a d a l growth and i t i s p l a u s i b l e t h a t the t i m i n g of gonadal growth i s i n f l u e n c e d by n u t r i e n t a v a i l a b i l i t y . S e v e r a l a u t h o r s i n d i c a t e d t h a t e x t e r n a l f o o d c o n d i t i o n s might d i r e c t l y s t i m u l a t e gonadal development, Pearse (1965, 1966) o b s e r v e d a marked synchrony i n gametogenesis i n d i f f e r e n t p o p u l a t i o n s of the s e a s t a r , O d o n t a s t e r v a l i d u s , i n t h e A n t a r c t i c , where t h e annual t e m p e r a t u r e range i s o n l y 0.8 °C, and su g g e s t e d t h a t t h i s synchrony s t a r t s w i t h t h e a c c u m u l a t i o n o f n u t r i e n t s d u r i n g the summer p e r i o d o f p h y t o p l a n k t o n abundance.. S i m i l a r l y , H o l l a n d (1967) s p e c u l a t e d t h a t the w e l l d e f i n e d r e p r o d u c t i v e c y c l e of the u r c h i n , S t y l o c i d a r i s a f f i n u s , l i v i n g i n the M e d i t e r r a n e a n under a l m o s t c o n s t a n t t e m p e r a t u r e , oxygen c o n c e n t r a t i o n and s a l i n i t y c o n d i t i o n s , was r e l a t e d t o t h e a n n u a l p h o t o p e r i o d c y c l e or consequent changes i n t h e a v a i l a b i l i t y o f a l g a l f o o d . I n some b a r n a c l e s and copepods i n temperate w a t e r s , t h e r e a r e s e v e r a l b r e e d i n g p e r i o d s d u r i n g s p r i n g t h r o u g h autumn, and i t has been i n d i c a t e d t h a t r e g e n e r a t i o n o f t h e gonads i s dependent on the a v a i l a b i l i t y of f o o d ( M a r s h a l l . & Orr, 1955.; C r i s p & D a v i s , 1955; C o r k e t t & McLaren, 1969; Barnes 6 B a r n e s , 1975). I n c o n t r a s t , i n some b o r e o — a r c t i c b a r n a c l e s , f o o d a v a i l a b i l i t y i s n o t t h e major cue f o r gonadal development, a l t h o u g h i t has been demonstrated t h a t the de c r e a s e i n t h e food s y p p l y i n the autumn h a s t e n s t h e l a t t e r s t a g e s of gametogenesis ( C r i s p . & P a t e l , 1969). Thus, f o r some s p e c i e s f o o d s u p p l y may i n f l u e n c e g onadal development. , 96 k number of s t u d i e s on marine i n v e r t e b r a t e s have been concerned w i t h the s o u r c e s of n u t r i e n t s f o r gonadal development, and some c o n t r a s t i n g s t r a t e g i e s have been d e s c r i b e d . , I n the s e a s t a r , P i s a s t e r o c h r a c e u s , most f e e d i n g o c c u r s i n t h e summer when t h e gonads a r e s m a l l and l i t t l e o c c u r s i n t h e Winter when the gonads are e n l a r g i n g (Farmanfarmaian, G i e s e , B o o l o o t i a n & B e n n e t t , 1958; G r e n f i e l d , G i e s e , Farmanfarmaian, & B o o l o o t i a n , 1958; fiauzey, 1966; N i m i t z , 1971) . There i s a r e c i p r o c a l d ecrease i n the s i z e o f the h e p a t i c caecae as the gonads grow, s u g g e s t i n g t h a t r e s e r v e s i n the h e p a t i c caecae are used f o r gamete p r o d u c t i o n . I n c o n t r a s t , t h e u r c h i n , S t r o n q y i o c e n t r o t u s e u r p u r a t u s , does not appear t o have a major s t o r a g e organ a p a r t from the gonad i t s e l f , and t o a l a r g e e x t e n t n u t r i e n t s f o r g o n a d a l growth p r o b a b l y come d i r e c t l y from i n g e s t e d f o o d ( G i e s e , 1959b, 1966).,,. G i e s e s u g g e s t s t h a t t h e d i f f e r e n c e s i n t h e s e two a n i m a l s may have e v o l v e d i n response t o d i f f e r e n c e s i n the a v a i l a b i l i t y o f t h e i r f o o d s , s i n c e t h e f o o d s u p p l y of the omnivorous u r c h i n may be more c o n t i n u o u s than t h a t o f the s e a s t a r . However, Hauzey (1966) s u g g e s t e d t h a t f o r P i s a s t e r the e f f i c i e n c y of f e e d i n g may be g r e a t e s t i n t h e summer, and t h a t r e d u c e d f e e d i n g i n the w i n t e r would i n c r e a s e the space i n t h e arms, t h u s a l l o w i n g g r e a t e r gamete p r o d u c t i o n . S e v e r a l s t u d i e s d e a l w i t h n u t r i e n t s u p p l y f o r g o n a d a l development i n K a t h a r i n a t u n i c a t a . N i m i t z and G i e s e (1964), from h i s t o l o g i c a l o b s e r v a t i o n s , r e p o r t t h a t n u t r i e n t s f o r gamete p r o d u c t i o n are d e r i v e d p r i m a r i l y from r e s e r v e s i n t h e gonad i t s e l f o r from i n g e s t e d f o o d . , When they s t a r v e d a n i m a l s f o r 5 months i n a p e r i o d p r i o r t o spawning, normal but fewer gametes 97 were produced., The gonads, however, d i d not i n c r e a s e i n s i z e , whereas a c o n t r o l group f e d P e l y e t i a and I j i d ^ g h y c u s d i d show gonad a l growth, a l t h o u g h n o t as g r e a t as i n t h e f i e l d a n i m a l s . , Lawrence, Lawrence and Giese (1965) found t h a t the s i z e o f t h e d i g e s t i v e g l a n d o f K . , t u n i c a t a had a s e a s o n a l c y c l e which was i n v e r s e t o t h a t o f t h e gonad, and suggested t h a t i t had a s t o r a g e f u n c t i o n . I n a l a t e r s t u d y , Lawrence and G i e s e (1969) kept a n i m a l s a t 13 °C w i t h o u t a s u p p l y of f o o d . a f t e r f o u r and a h a l f months t h e r e was a marked drop i n l i p i d l e v e l s i n t h e f o o t and mantle, w h i l e the gonads showed a s l i g h t i n c r e a s e i n l i p i d c o n t e n t and t h e gonadal i n d e x r o s e from 1,0 t o 2.7. Meanwhile, t h e go n a d a l i n d e x i n f i e l d a n i m a l s r o s e t o 8.0, but t h e r e was a drop i n l i p i d l e v e l s i n the f o o t , mantle and d i g e s t i v e g l a n d comparable t o t h a t i n t h e s t a r v e d a n i m a l s . , Lawrence and G i e s e i n t e r p r e t t h i s t o mean t h a t t h e p o s s i b l e n u t r i e n t r e s e r v e s i n s o m a t i c body organs are not enough f o r normal gonadal growth and t h a t a d d i t i o n a l n u t r i e n t s must come from i n g e s t e d f o o d . , G i e s e and Hart (1967) s t u d i e d changes i n th e b i o c h e m i c a l c o n s t i t u e n t s o f v a r i o u s body o r g a n s of K. t u n i c a t a t h r o u g h o u t the year and c o n c l u d e d t h a t d u r i n g gamete p r o d u c t i o n , c a r b o h y d r a t e i n t h e gonad i s c o n v e r t e d t o p r o t e i n i n the t e s t e s and t o p r o t e i n and l i p i d i n t h e o v a r y . Thus, i t appears t h a t K. t u n i c a t a r e l i e s on both s t o r e d and i n g e s t e d n u t r i e n t s f o r gamete p r o d u c t i o n . F o r a v a r i e t y o f i n v e r t e b r a t e s , both f o o d q u a n t i t y and q u a l i t y a r e r e p o r t e d t o i n f l u e n c e t h e amount o f gametes produced (Moore, 1937; Ve v e r s , 1949; Vadas, 1968; E b e r t , 1968)., From numerous o b s e r v a t i o n s on t h e f e e d i n g o f K. t u n i c a t a i n t h e 98 f i e l d , as w e l l as o b s e r v a t i o n s on gut c o n t e n t s , I have c o n c l u d e d t h a t t h e main f o o d of K. t u n i c a t a i s t h e phaeophyte Hedophyllum s e s s i l e , the a l g a i t i s most commonly a s s o c i a t e d w i t h . I n N i m i t z and . G i e s e ' s (1964) experiment th e c o n t r o l a n i m a l s were fe d P e l y e t i a and I r i d p p h y c u s and t h i s d i e t may not have been as n u t r i t i o u s as t h e d i e t a v a i l a b l e t o f i e l d a n i m a l s ; t h i s c o u l d p o s s i b l y have caused the reduced gonadal growth i n t h e l a b o r a t o r y a n i m a l s . The presence of gametes a f t e r 5 months of s t a r v a t i o n i n N i m i t z and G i e s e ' s e x p e r i m e n t , and t h e s l i g h t i n c r e a s e i n the mean gonadal i n d e x o f a n i m a l s s t a r v e d by Lawrence and G i e s e (1969) [ t h e y do not i n d i c a t e whether mature gametes were produced] s u g g e s t s t h a t a f t e r November t h e gametogenic p r o c e s s i n K. t u n i c a t a w i l l c o n t i n u e i r r e s p e c t i v e of l a b o r a t o r y and f o o d c o n d i t i o n s . However, i n K. t u n i c a t a , as i n o t h e r s p e c i e s , f o o d does appear t o a f f e c t the amount o f gametes produced. I n some marine i n v e r t e b r a t e s i t has been demonstrated t h a t the r a t e of f o o d consumption d e c r e a s e s at the time when the gonads a r e i n c r e a s i n g i n s i z e , even when e x c e s s f o o d i s a v a i l a b l e . , T h i s has been r e p o r t e d f o r S t r o n g y l o c e n t r o t u s ii}£ermedius» S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s and S t r o n g y l p c e n -t r o t u s p u r p u r a t u s ( F u j i , 1962, 1967; E b e r t , 1966; Himmelman, 1969). E b e r t (1966) suggested t h a t t h i s may be due t o t h e s i z e o f t h e gonads, s i n c e t h e r e i s not enough room i n the t e s t f o r a l a r g e gut and l a r g e gonads, a l t h o u g h he a l s o i n d i c a t e d t h a t f o o d may be l e s s abundant i n the f i e l d when gonadal growth i s o c c u r r i n g . F u j i (1962) c o n s i d e r e d t h a t t h e r e d u c t i o n i n t h e f e e d i n g r a t e was a p h y s i o l o g i c a l response to t h e gonadal 99 development. A s e a s o n a l c y c l e i n the . f e e d i n g r a t e o f K. t u n i c a t a a t B o t a n i c a l Beach Mas d e s c r i b e d by Himmelman and C a r e f o o t (1975), D u r i n g A u g u s t - e a r l y September 1971 about 0.9 g of fledoghyllum s e s s i l e were consumed d a i l y . K. t u n i c a t a a t t h i s time had s m a l l gonads. In October and December o n l y 0.3-0.6 g were consumed d a i l y and a t t h i s t i m e t h e gonads were e n l a r g i n g . The h i g h e s t f e e d i n g r a t e s o c c u r r e d i n May-July 1972, about 1.2 g d a i l y , when spawning was n o t yet c o m p l e t e d , and tne r a t e a g a i n dropped i n t h e l a t e summer when t h e a n i m a l s were s p e n t . , Thus, the f e e d i n g r a t e of K. t u n i c a t a was low when the gonads were b e g i n n i n g t o grow, but i n c o n t r a s t t o t h e u r c h x n s , f e e d i n g i n c r e a s e d b e f o r e spawning was completed. I n a l l o f t h e above s p e c i e s the f e e d i n g r a t e decreased as the gonads were e n l a r g i n g , but t h e r e was no e v i d e n c e t h a t a change i n t h e f o o d s u p p l y s t i m u l a t e d g o n a d a l growth. Many o t h e r f a c t o r s may i n f l u e n c e t h e n u t r i t i o n of an a n i m a l (eg. see re v i e w on e c h i n o i d n u t r i t i o n by Lawrence, 1975). The amount o f n u t r i e n t s a v a i l a b l e t o an a n i m a l may n o t d e c r e a s e i n p r o p o r t i o n t o t h e decrease i n f e e d i n g r a t e a t t h e t i m e o f gonadal growth. For example, i n S t r o n g y l o c e n t r o t u s i n t e r m e d i n s and S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s t h e weight of f o o d absorbed per weight i n g e s t e d i n c r e a s e s as l e s s f o o d i s p a s s i n g t h r o u g h the gut ( F u j i , 1962, 1967; Himmelman, 1969). A l s o t h e g u a l i t y o f f o o d i n t h e f i e l d may change i n d i f f e r e n t seasons. For example, a t B o t a n i c a l Beach, Himmelman and C a r e f o o t (1975) found t h a t t h e r e i s an i n c r e a s e i n t h e c a l o r i f i c c o n t e n t o f the phaeophytes, Hedophyllum s e s s i l e and L e s s o n i g p s i s l i t t o r a i i s , and o f the r h o d o p h y t e , I r i d a e a c o r d a t a , d u r i n g t h e l a t e summer 100 t o e a r l y w i n t e r and a de c r e a s e i n the s p r i n g . Thus, a t B o t a n i c a l Beach d u r i n g t h e p e r i o d when g o n a d a l growth o c c u r s i n K a t h a r i n a t u n i c a t a , S t r o n g y l o c e n t r o t u s . d r o e b a c h i e n s i s and S t r o n g y l o c e n t r o t u s £J!££uratus t h e c a l o r i c i n t a k e o f the s e a n i m a l s may not have decrea s e d i n p r o p o r t i o n t o the r e d u c t i o n i n t h e i r f e e d i n g r a t e s . The r e v e r s e s i t u a t i o n appears t o be t h e c a s e f o r SJtr o n j j y l o -c e n t r o t u s d r o e b a c h i e n s i s p o p u l a t i o n s f e e d i n g on L a m i n a r i a l o n g i c r u r i s i n S t . Margaret's Bay, Nova S c o t i a . Data p r e s e n t e d by Mann (1972) i n d i c a t e t h a t the c a l o r i c c o n t e n t o f t h i s a l g a on a l i v e weight b a s i s would have a s e a s o n a l c y c l e which i s t h e r e v e r s e t o t h a t o b s e r v e d f o r t h e t h r e e west c o a s t a l g a e (Himmelman and C a r e f o o t , 1975)., C o n s e q u e n t l y , S t r o n g y l o c e n t r q t -us d r o e b a c h i e n s i s f e e d i n g on t h i s a l g a would have a marked s e a s o n a l f l u c t u a t i o n i n c a l o r i c i n t a k e , T h i s was c o n f i r m e d by M i l l e r and Mann (1973). They r e p o r t e d t h a t t h e number o f c a l o r i e s consumed, as w e l l as t h e number o f c a l o r i e s a b s o r b e d , •by S. d r o e b a c h i e n s i s f e e d i n g on L a m i n a r i a l o n g i c r u s i s d e c r e a s e s from June t o March, but from August t o March t h e r e was an i n c r e a s e i n t h e number or c a l o r i e s c h a n n e l l e d i n t o g onadal growth and l i t t l e c h a n n e l l e d i n t o somatic growth.,, I n t h e i r e x p e r i m e n t s , t h e a n i m a l s were p r o v i d e d w i t h excess f o o d . Thus i t would not appear t h a t food a v a i l a b i l i t y caused the change i n energy f l o w from s o m a t i c t o gonadal . growth. , Temperature . and p h o t o p e r i o d approximated t h a t i n t h e field.„ I t i s i n t e r e s t i n g t h a t M i l l e r and Mann (1973) r e p o r t t h e r e was a decrease i n t h e c a l o r i f i c c o n t e n t of t h e gonad/g wet weight from June t o March, •when the gonads were i n c r e a s i n g i n s i z e . , T h i s i s p r i m a r i l y due 101 t o an i n c r e a s e i n water c o n t e n t , t h u s i n d i c a t i n g t h a t some, of the enlargement as measured by t h e gonadal i n d e x i s not due t o th e a d d i t i o n o f o r g a n i c m a t e r i a l s . An i n c r e a s e i n water c o n t e n t as t h e gonads i n c r e a s e i n s i z e has a l s o been noted i n S t r o n g y -i°£S3.t£2.tus p u r p u r a t u s (A. L. Lawrence & J . M. ,.Lawrence i n G i e s e , 1 966) . In summary, f o r growth i n some s p e c i e s t h e r e must be an in c o m i n g s u p p l y of n u t r i e n t s from i n g e s t e d f o o d d u r i n g t h e p e r i o d when the gonads a r e gr o w i n g , w h i l e i n o t h e r s , p r o v i d e d t h a t t h e r e i s soma s t o r a g e of m a t e r i a l s , gonadal development w i l l proceed even when t h e r e i s no food a v a i l a b l e . F o r most s p e c i e s poor f o o d g u a l i t y o r a s c a r c i t y of food w i l l r e d u c e the numbers of gametes produced. There i s no e v i d e n c e s u g g e s t i n g t h a t g o n a d a l development i n the s p e c i e s c o n s i d e r e d . i n the p r e s e n t s t u d y i s s t i m u l a t e d by changes i n f o o d g u a l i t y o r a v a i l a b i l i t y . P o s s i b l e F a c t o r s R e g u l a t i n g Spawning I t i s l i k e l y t h a t some mechanism has e v o l v e d t o ensure t h a t spawning w i l l o c c u r when c o n d i t i o n s a r e f a v o u r a b l e f o r bo t h f e r t i l i z a t i o n and l a r v a l development. , F o r a n i m a l s which shed t h e i r gametes d i r e c t l y i n t o the s e a , the p r o b a b i l i t y of f e r t i l i z a t i o n w i l l be d i r e c t l y , r e l a t e d t o . t h e degree of s y n c h r o n i z a t i o n o f spawning amongst a n i m a l s i n a p o p u l a t i o n ; and when synchronous spawning o c c u r s i t i s p r o b a b l y i n r e s p o n s e t o e x t e r n a l cues (Giese & P e a r s e , 1974), I n examining t h e s t i m u l u s 102 f o r spawning, both p h y s i c a l and b i o t i c c o n d i t i o n s r e q u i r e d f o r the s u c c e s s of l a r v a l s t a g e s s h o u l d be c o n s i d e r e d . , One would e x p e c t a change i n one or more e n v i r o n m e n t a l f a c t o r s a t t i m e o f , o r j u s t p r i o r t o , spawning. A l t e r n a t i v e l y , i n some s p e c i e s the s t i m u l u s f o r spawning may preceed the f a v o u r a b l e p e r i o d f o r l a r v a l growth, so t h a t the l a r v a e have developed t o a s t a g e where t h e y can t a k e f u l l advantage o f t h e f a v o u r a b l e p e r i o d ( P e a r s e , 1965) . Many r e s e a r c h e r s have i n v e s t i g a t e d t h e s t i m u l u s f o r spawning. However, t h e r e a r e r e l a t i v e l y few organisms f o r which t h e spawning cue (s) has been e l u c i d a t e d . , Orton's (1920) work has been f r e g u e n t l y r e f e r r e d t o , but i t s h o u l d be n o t e d t h a t he d i d not d i s t i n g u i s h between the c o n d i t i o n s which s t i m u l a t e d g onadal development and those r e s p o n s i b l e f o r spawning. Many r e p o r t s a r e p u r e l y d e s c r i p t i v e and spawning f a c t o r s may be s u g g e s t e d but u s u a l l y w i t h o u t e x p e r i m e n t a l p r o o f . , A s u r p r i s i n g number of h a r s h t r e a t m e n t s , f o r example e l e c t r i c a l shock, s c r a p i n g t h e a n i m a l s , exposure t o K r a f t p u l p m i l l e f f l u e n t and o t h e r c h e m i c a l s , are known t o cause spawning i n t h e l a b o r a t o r y (Young, 1945; B r e e s e , M i l l e m a n n & Dimick, 1963), but i t i s d i f f i c u l t t o imagine t h e i r r o l e i n n a t u r a l spawning. Temperature Temperature more than any o t h e r f a c t o r has been c o n s i d e r e d t o c o n t r o l spawning. There i s a d i s t i n c t a n n u a l t e m p e r a t u r e c y c l e i n most s h a l l o w water h a b i t a t s and many workers c o n s i d e r 0 103 t h a t spawning s t a r t s when a p h y s i o l o g i c a l t h r e s h o l d t e m p e r a t u r e i s r e a c h e d , or when t h e r e i s a sudden change i n t e m p e r a t u r e . , For example, C l i p p e r f i e l d (1953) r e p o r t s t h a t i n a number o f l o c a t i o n s i n G r e a t B r i t a i n M y t i l u s e d u l i s spawns when t h e mean sea temperature r i s e s from 9.5 t o 11-12.5 °C. He s u g g e s t s t h a t spawning i s s t i m u l a t e d by t h i s t e m p e r a t u r e r i s e , a l t h o u g h he a l s o i n d i c a t e s t h a t l a b o r a t o r y s t u d i e s produced c o n f l i c t i n g r e s u l t s . M y t i l u s e d u l i s i s p r o b a b l y exposed t o a t l e a s t a 3 °C change d u r i n g every daytime low t i d e . L o o s a n o f f and D a v i s (1963) r e p o r t t h a t t h e y c o u l d not i n d u c e t h i s s p e c i e s t o spawn by t h e r m a l shock. Orton (1920) r e p o r t s t h a t Q s t r e a - e d u l i s spawns when t h e t e m p e r a t u r e r e a c h e s t h e c r i t i c a l l e v e l of 15-16 °C, but l a t e r s t u d i e s on t h i s s p e c i e s i n d i c a t e t h a t a l t h o u g h a c e r t a i n temperature i s r e g u i r e d f o r gonadal m a t u r a t i o n , t e m p e r a t u r e does not a c t as a " t r i g g e r " f o r spawning ( K o r r i n g a , 1957), T h i s appears to be t r u e o f many s p e c i e s . L o o s a n o f f and D a v i s (1963) s t u d i e d 19 s p e c i e s o f l a m e l l i b r a n c h s and r e p o r t t h a t most of them r i p e n e d out of season when s u b j e c t e d t o warmer t e m p e r a t u r e s , but t e m p e r a t u r e does not a l w a y s s t i m u l a t e spawning. The s t a n d a r d t e c h n i g u e L o o s a n o f f and D a v i s used t o i n d u c e spawning was a sudden r i s e i n t e m p e r a t u r e of 5-10 °C and the a d d i t i o n o f g o n a d a l t i s s u e s . T h i s t r e a t m e n t was o n l y r e l i a b l e f o r about h a l f o f t h e s p e c i e s , and o n l y a s m a l l number c o u l d be i n d u c e d t o spawn by a temperature change a l o n e . I t i s u n l i k e l y t h a t M. e d u l i s , Q s t r e a e d u l i s , and t h e l a m e l l i b r a n c h s s t u d i e d by L o o s a n o f f and D a v i s n a t u r a l l y e n c o u n t e r sudden te m p e r a t u r e changes s u f f i c i e n t to s t i m u l a t e spawning.. Thus, w h i l e t e m p e r a t u r e i s o f t e n r e f e r r e d t o as the s t i m u l u s f o r 104 spawning, t h i s has u s u a l l y not been a d e g u a t e l y demonstrated. F i e l d o b s e r v a t i o n s made d u r i n g t h e p r e s e n t study i n d i c a t e d t h a t t h e r e was u s u a l l y a s l i g h t i n c r e a s e i n t h e r a t e o f warming d u r i n g t h e spawning p e r i o d , compared t o the p e r i o d p r i o r t o spawning, but t h e t o t a l t emperature i n c r e a s e was s t i l l s m a l l . , a t F i r s t Harrows, S t r o n q y l o c e n t r o t u s d r o e b a c h i e n s i s , T o n i c e l l a l i n e a t a , T o n i c e l l a i n s i g n i s , M o p a l i a l a e v i o r and M o p a l i a c i l i a t a had a major spawning when t h e temperature r e a c h e d 7—8 °C, e x c e p t f o r S. d r o e b a c h i e n s i s i n the c o l d s p r i n g o f 1970 when spawning o c c u r r e d a t 6,3 °C. The temp e r a t u r e was 7.5—8.3 °C a t P o r t e a u when T. l i n e a t a , T. i n s i g n i s and M. l a e v i o r spawned i n 1973. At B o t a n i c a l Beach i n some y e a r s K. t u n i c a t a spawned when t e m p e r a t u r e s were a t l e a s t 9 °C and i n o t h e r y e a r s spawned when t e m p e r a t u r e s were 1—2 °C c o l d e r , , T, l i n e a t a , M o g a l i a h i n d s i i , M . . c i l i a t a and S, d r o e b a c h i e n s i s p r o b a b l y spawned a t h i g h e r t e m p e r a t u r e s a t B o t a n i c a l Beach t h a n a t F i r s t Narrows, and t h e r e was c o n s i d e r a b l e warming o v e r the p r o l o n g e d spawning p e r i o d of S t r o n g y . l o c e n t r o t u s ^ u r p u r a t u s a t B o t a n i c a l Beach. The a b r u p t spawning i n most of the s p e c i e s i n the p r e s e n t s t u d y s u g g e s t s t h a t spawning happens as a s e n s i t i v e r e s ponse o f t h e a n i m a l s t o an e x t e r n a l s t i m u l u s . , At P o r t e a u i n 1973 t h e r e was a g r a d u a l r i s e o f not more th a n 0.8 °C over the two week p e r i o d when the complete spawning o c c u r r e d . I n t h i s c a s e , i f t e m p e r a t u r e was the spawning s t i m u l u s , the a n i m a l s must have had a very p r e c i s e t e m p e r a t u r e t h r e s h o l d . Such a p r e c i s e temperature t h r e s h o l d was not i n d i c a t e d by the v a r i a b l e c o r r e l a t i o n o f te m p e r a t u r e w i t h spawning i n d i f f e r e n t y e a r s a t B o t a n i c a l Beach, o r by t h e d i f f e r e n c e s i n t e m p e r a t u r e a t t h e t i m e of spawning between F i r s t 105 Harrows and B o t a n i c a l Beach. I n c o n t r a s t t o Ort o n ' s (1920) h y p o t h e s i s o f a p h y s i o l o g i c a l l y c o n s t a n t spawning, i t i s c l e a r f o r t h e s p e c i e s i n t h e p r e s e n t s t u d y t h a t t e m p e r a t u r e s a t t h e t i m e o f spawning vary c o n s i d e r a b l y i n w i d e l y s e p a r a t e d g e o g r a p h i c a l l o c a t i o n s . Most of the s p e c i e s range a t l e a s t from c e n t r a l C a l i f o r n i a t o A l a s k a , and w h i l e the annual t e m p e r a t u r e minimum i n C e n t r a l C a l i f o r n i a i s about 11 °C, the same l e v e l i s near t h e a n n u a l maximum f o r A l a s k a . Barnes (1972) showed t h a t the tem p e r a t u r e was about 11 °C when T o n i c e l l a l i n e a t a spawned i n Oregon, whereas a t F i r s t Harrows and P o r t e a u i t was 7—8 °C., Mean t e m p e r a t u r e s were always above 12 °C when K a t h a r i n a t u n i c a t a spawned i n the Monterey a r e a , and i n the p r e s e n t study, were p r o b a b l y always l e s s than 11 °C. I n Newfoundland, S t r o n g y l o c e n -t£otus d r o e b a c h i e n s i s spawned when te m p e r a t u r e s were l e s s than 3 °C (Himmelman, 1969) w h i l e i n t h e p r e s e n t s t u d y t h i s s p e c i e s spawned a t t e m p e r a t u r e s above 6 °C. In my l a b o r a t o r y s t u d i e s , a n i m a l s c o l l e c t e d p r i o r t o spawning and kept i n c o n d i t i o n s warmer and c o l d e r and l i g h t e r and d a r k e r t h a n i n t h e f i e l d d i d not spawn when spawning o c c u r r e d i n t h e f i e l d . F u r t h e r , i n t h e 1973 e x p e r i m e n t s , no spawning o c c u r r e d when the c o o l i n g system f a i l e d , c a u s i n g a temperature i n c r e a s e of 5 °C i n two ho u r s . Barnes (1972) a l s o r e p o r t e d t h a t he c o u l d not i n d u c e spawning i n T o n i c e l l a l i n e a t a by t e m p e r a t u r e and o t h e r s t i m u l i . . He t r i e d a l t e r n a t i n g h e a t and c o l d , a l t e r n a t i n g l i g h t and dark p e r i o d s , g u i e t water c o n d i t i o n s and e l e c t r i c a l shock w i t h no s u c c e s s . Matanabe and Cox (1975) 106 t r i e d t o i n d u c e M o p a l i a I i g n o s a and M o g a l i a muscosa to spawn by-t h e r m a l shock, e l e c t r i c a l , c h e m i c a l and m e c h a n i c a l s t i m u l a t i o n . The o n l y s i t u a t i o n i n which a n i m a l s spawned was when t h e y were p l a c e d i n sea water and l e f t u n t i l t h e water became s t a l e , , I t seems u n l i k e l y t h a t t h e s l i g h t t e m p e r a t u r e changes which o c c u r r e d i n t h e f i e l d would have i n d u c e d t h e sudden spawning observed i n most of t h e s p e c i e s i n my s t u d y . There i s s u f f i c i e n t e v i d e n c e t h a t i n some s p e c i e s a c e r t a i n t e m p e r a t u r e l e v e l i s n e c e s s a r y f o r spawning t o o c c u r . F o r example, spawning i n M y t i l u s e d u l l s , C r a s s o s t r e a v i r g i n i c a , and H e r c e n a r i a m e r c e n a r i a i s i n h i b i t e d when a n i m a l s a r e exposed t o l o w e r e d t e m p e r a t u r e s ( G a l t s o l f , 1938; L o o s a n o f f & D a v i s , 1951, 1963: Bayne, 1965), These c r i t i c a l t e m p e r a t u r e l e v e l s f o r gametogenesis and spawning a r e not c o n s t a n t , but may v a r y i n d i f f e r e n t p o p u l a t i o n s throughout t h e i r g e o g r a p h i c a l range ( L o o s a n o f f , 1968) . Temperatures r e q u i r e d f o r spawning a r e p r o b a b l y r e l a t e d t o t h o s e r e g u i r e d f o r normal development o f t h e embryos and l a r v a e . For a number of b i v a l v e s and f o r some o t h e r i n v e r t e b r a t e s i t has been demonstrated t h a t the l a r v a e have narrower t e m p e r a t u r e t o l e r a n c e s t h a n do the a d u l t s , and t h a t e a r l y c l e a v a g e s t a g e s may have even narrower temperature t o l e r a n c e s than t h e l a r v a e ( P e l s e n e e r , 1901; fiunnstrom, 1927a; L o o s a n o f f & D a v i s , 1963; Kennedy, Boosenburg, Z i o n & C a s t a n g a , 1974; Kennedy, fioosenburg, Castagna and M i h u r s k y , 1974). S a s t r y (1966) s t a t e s t h a t t h e lower temperature l i m i t f o r spawning i n t h e bay s c a l l o p , A e g u i p e c t e n i r r i d i a n s , c o r r e s p o n d s t o t h e l o w e r t e m p e r a t u r e 107 l i m i t f o r c l e a v a g e . , G a l t s o l f (1938) r e p o r t s t h a t t h e American o y s t e r , C r a s s o s t r e a y i r g i n i c a , can he i n d u c e d t o spawn a t 20.5 °C but not a t 18.0 °C [ a l t h o u g h L o o s a n o f f and Nomejko (1951) r e p o r t t h a t t h i s s p e c i e s sometimes spawns a t t e m p e r a t u r e s as low as 16.5—18.5 °C] and D a v i s and C a l a b r e s s e (1964) r e p o r t t h a t C r a s s o s t r e a y l r g i n i c a l a r v a e show a p r o g r e s s i v e i n c r e a s e i n growth r a t e from 17.5—30.0 °C. The l a r v a e o f the European o y s t e r , Q s t r e a e d u l i s can s u r v i v e t e m p e r a t u r e s o f 12.5—27.5 °C and grows be s t above 17.5 °C (Davis & C a l a b r e s s e , 1969). T h i s c o r r e s p o n d s t o the r e g u i r e d spawning t e m p e r a t u r e r e p o r t e d by O r t o n (1920) f o r t h i s s p e c i e s . E x p e r i m e n t s by Bayne (1965) on the m u s s e l , M y t i l u s e d u l i s , i n North S a l e s and Denmark . i n d i c a t e t h a t normal c l e a v a g e o c c u r s between 8—18 °C. , There i s a marked i n c r e a s e i n l a r v a l growth r a t e from 10—13 °C and a d e c r e a s e above 18 °C i n l a r v a e from Denmark, but not i n l a r v a e from North H a l e s . As noted e a r l i e r , M y t i l u s e d u l i s i n B r i t i s h w a t e r s spawns as t h e mean temp e r a t u r e r i s e s from 9.5 t o 11—12.5 °C ( C l i p p e r f i e l d , 1953).... Thus, f o r t h e s e and o t h e r s p e c i e s n a t u r a l spawning appears t o o c c u r when t e m p e r a t u r e s a r e f a v o u r a b l e f o r the temperature s e n s i t i v e l a r v a l s t a g e s , For a number o f the s p e c i e s i n t h e p r e s e n t s t u d y , d e v e l o p m e n t a l r a t e s under v a r i o u s t e m p e r a t u r e s have been r e p o r t e d (Table V I I ) . Temperature t o l e r a n c e s have o n l y been determined f o r S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s , and t h e t e m p e r a t u r e s a t which t h e o t h e r s p e c i e s were s t u d i e d were p r o b a b l y c o n s i d e r e d by the r e s p e c t i v e r e s e a r c h e r s t o be w i t h i n a n a t u r a l or f a v o u r a b l e range f o r development., The embryos and l a r v a e of S, d r o e b a c h i e n s i s has normal development from ~1 t o 108 Table VII. Beported developmental times under various temperatures for the species i n the present study. Length of Time of hatching free-swimming Chours a f t e r f e r t i l i z a t i o n ) period Reference Strongylocentrotus droe normal development between -1 and 11 C droebachiensis 2.5 months 9 weeks normal development between -1 and 9 °C 80 h (0 °C) 50 h (4 °C) 30 h (8 °C) RunnstrOm, 1927a Runnstrem, 1927b Turner, 1965 > Stephens, 1972 Mopalia c i l i a t a 36-42 h (normal sea temp-erature, probably 10 C) 12-24 h (12-15 °C) 7-14 days I Thorpe, 1962 Mopalia lignosa  Mopalia muscosa T o n i c e l l a l i n e a t a 19-25 h (13 C) 20-24 h (13 C) 48 h (10 C) 43-44 h (12-13 °C) 4.5 days (13 C) 10 days (13 C) 4.5 days (10 C) 2.7 days (12 13 °C) J Watanabe & Cox, 1975 Watanabe & Cox, 1975 Barnes, 1972 109 9—11 °C and i t s growth r a t e w i t h i n t h i s range i n c r e a s e s w i t h i n c r e a s i n g temperature* The s t u d i e s on M o g a l i a muscosa, M o p a l i a AiSLSSsa, M o g a l i a c i l i a t a and T o n i c e l l a l i n e a t a -were made i n C a l i f o r n i a and Oregon and t h e r e was normal development i n t h e s e s p e c i e s a t 10—15 °C. I n the l a t t e r two s p e c i e s growth i n c r e a s e d w i t h i n c r e a s i n g temperature (Table V I I ) . , D u r i n g t h e p r e s e n t s t u d y spawning i n t h e above c h i t o n s p e c i e s p r o b a b l y o c c u r r e d w i t h i n a temperature range s u i t a b l e f o r l a r v a l development., However, i n S , . d r o e b a c h i e n s i s , i t i s p o s s i b l e t h a t i n some a r e a s of s o u t h e r n B r i t i s h C o lumbia, e s p e c i a l l y i n t h e S t r a i t o f G e o r g i a , l e t h a l t e m p e r a t u r e s may sometimes be r e a c h e d b e f o r e l a r v a l development i s completed. In summary, a l t h o u g h t e m p e r a t u r e i s known t o be an i m p o r t a n t s t i m u l u s f o r gonadal growth and m a t u r a t i o n i n numerous s p e c i e s , t h e r e a r e few s u b s t a n t i a t e d i n s t a n c e s o f t e m p e r a t u r e a c t i n g as a s t i m u l u s f o r n a t u r a l spawning. In S t r o n g y l o c e n t r o t -us d r o e b a c h i e n s i s , T o n i c e l l a l i n e a t a , T o n i c e l l a i n s i g n i s and p r o b a b l y o t h e r s p e c i e s i n my s t u d y , i t appears u n l i k e l y t h a t t e m p e r a t u r e a c t e d as a cue f o r spawning. F o r a number of marine i n v e r t e b r a t e s i t i s c l e a r t h a t n a t u r a l spawning o c c u r s when t e m p e r a t u r e s a r e f a v o u r a b l e f o r l a r v a l development, and f o r some s p e c i e s reduced t e m p e r a t u r e s w i l l i n h i b i t spawning, t h e r e b y a c t i n g a s a s a f e g u a r d a g a i n s t t h e waste of gametes. 110 L i g h t L i g h t has been shown t o a c t as a cue f o r s y n c h r o n o u s r e l e a s e o f gametes i n s e v e r a l marine i n v e r t e b r a t e s . D u r i n g the b r e e d i n g seasons of s e v e r a l s p e c i e s of h y d r o i d s spawning o c c u r s i n t h e e a r l y morning., B a l l a r d (1942) demonstrated t h a t t h i s was s o l e l y i n response t o l i g h t a f t e r a p e r i o d of d a r k n e s s . R e — i l l u m i n a t i o n a c t i v a t e s t h e germ c e l l s t o undergo t h e f i n a l s t a g e s o f m a t u r a t i o n (even i n o o c y t e s d i s s e c t e d from the animals) and a f t e r a p e r i o d o f 55 minutes i n l i g h t , mature gametes r u p t u r e from the w a l l s of t h e gonophores. A l s o , some a s c i d i a n s are known t o spawn when exposed t o l i g h t a f t e r a p e r i o d o f d a r k n e s s . Lambert and B r a n t (1967) s u g g e s t s t h a t spawning i n C i g n a i n t e s t i n a l i s i s i n i t i a t e d when a nervous pathway i s s t i m u l a t e d by heme-proteins which absorb l i g h t . K o r r i n g a (1947) s u g g e s t s t h a t t h e presence o r absence o f m o o n l i g h t may be a f a c t o r i n a n i m a l s w i t h l u n a r spawning rhythms. C o n c e i v a b l y p h o t o p e r i o d c o u l d a c t as a s i g n a l f o r spawning i n c h i t o n s and u r c h i n s , but t h e v a r i a b l e spawning t i m e i n d i f f e r e n t p l a c e s and i n d i f f e r e n t y e a r s d u r i n g t h e p r e s e n t s t u d y do not s u p p o r t t h i s h y p o t h e s i s . , Chemical F a c t o r s Many c h e m i c a l s , f o r example a d r e n a l i n , t h y r o x i n , KC1 and ammoninated s e a water, a r e known t o cause r i p e a n i m a l s t o spawn ( G a l t s o l f , 1940; S a g a r a , 1958; B r e e s e , M i l l e m a n n D i m i c k , 1963). However, i t i s not known t h a t they a r e f u n c t i o n a l i n n a t u r e . 111 Sax p r o d u c t s , p a r t i c u l a r l y sperm, causes spawning i n many i n v e r t e b r a t e s (Heath, 1905; Fox, 1924), and t h e s e have o b v i o u s v a l u e i n i n c r e a s i n g the degree o f synchrony i n spawning amongst i n d i v i d u a l s i n a p o p u l a t i o n . I n t h e p r e s e n t s t u d y sperm s u s p e n s i o n s t i m u l a t e d spawning i n about t w o - t h i r d s of the S t r o n q y l o c e n t r g t u s d r o e b a c h i e n s i s , T o n i c e l l a l i n e a t a and T o n i c e l l a i n s i g n i s t e s t e d . T h i s t y p e o f s t i m u l a t i o n has been s t u d i e d most i n C r a s s o s t r e a v i r g i n i c a ( G a l t s o l f , 1938; Nelson,. £ A l l i s o n , 1940). Sperm s u s p e n s i o n i s u s u a l l y f a r more e f f e c t i v e than p h y s i c a l s t i m u l i (Young, 1945), and the r e s p o n s e t o sperm i s sometimes used as a c r i t e r i a f o r whether an a n i m a l i s i n c o n d i t i o n t o spawn ( G a l t s o l f , 1938, 1940). G a l t s o l f (1940) r e p o r t e d a s u b s t a n c e i n egg s u s p e n s i o n which s t i m u l a t e d spawning i n male C r a s s o s t r e a v i r ^ i n i c a . , T h i s s u b s t a n c e was t h e r m o s t a b l e and water s o l u b l e and t h u s resembled a s u b s t a n c e which M i y a z a k i (1938) e x t r a c t e d from t h e green a l g a e , U l y a and Entermorgha, which induced spawning i n the Japanese o y s t e r , C r a s s o s t r e a g i g a s . A v a r i e t y o f p l a n t s u b s t a n c e s ( m a l t o s e , a r a b i n o s e , s t a r c h and y e a s t ) a r e a l s o r e p o r t e d t o s t i m u l a t e spawning i n C r a s s o s t r e a v i r g i n i c a . Many e x t r a c e l l u l a r p r o d u c t s a r e r e l e a s e d by a l g a e ( H e l l e b u s t , 1974) and i t i s c o n c e i v a b l e that, some may cause n a t u r a l spawning. The h i g h e f f e c t i v e n e s s of c h e m i c a l s t i m u l a t i o n by sperm and o t h e r s u b s t a n c e s s u g g e s t s t h a t t h e n a t u r a l spawning s t i m u l u s i s c h e m i c a l . 112 P h y t o p l a n k t o n The c l o s e c o r r e l a t i o n of spawning w i t h the . development o f t h e s p r i n g p h y t o p l a n k t o n bloom i n s e v e r a l l o c a t i o n s i n 1973 and 1974, and t h e e x p e r i m e n t a l o b s e r v a t i o n t h a t n a t u r a l p h y t o p l a n k t o n s t i m u l a t e d spawning i n the l a b o r a t o r y , s u g g e s t s t h a t the p h y t o p l a n k t o n bloom a c t s as t h e cue f o r n a t u r a l spawning. As mentioned e a r l i e r , t h e a d d i t i o n of sperm i s r e p o r t e d t o be one o f the most e f f e c t i v e methods f o r i n d u c i n g spawning i n marine i n v e r t e b r a t e s , but i n the p r e s e n t s t u d y p h y t o p l a n k t o n was as e f f e c t i v e as sperm i n c a u s i n g spawning i n S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s . T o n i c e l l a l i n e a t a and T o n i c e l l a i n s i g n i s . I t i s p o s s i b l e t h a t p h y t o p l a n k t o n and sperm a c t through a s i m i l a r mechanism i n v o l v i n g chemoreceptors and a n e u r o e n d o c r i n e pathway. C e r t a i n l y t h i s p r e s e n t s an i n t e r e s t i n g p h y s i o l o g i c a l problem, and the s p e c i f i c i t y of the r e c e p t o r t o d i f f e r e n t p h y t o p l a n k t o n s p e c i e s i s o f e c o l o g i c a l i n t e r e s t . The v a r i o u s s p e c i e s i n the p r e s e n t s t u d y can be compared a c c o r d i n g t o t h e degree t o which t h e i r spawning c o i n c i d e d w i t h the p h y t o p l a n k t o n blooms,,, S. d r o e b a c h i e n s i s and T o n i c e l l a i n s i g n i s u s u a l l y spawned a b r u p t l y e a r l y i n the bloom, w h i l e !• Aill®ata spawned more .slowly d u r i n g t h e bloom.,, T.. ...lineata p r o b a b l y r e g u i r e s c o n t i n u o u s p h y t o p l a n k t o n s t i m u l a t i o n s i n c e a n i m a l s t r a n s f e r r e d from F i r s t Narrows t o the l a b o r a t o r y i n t h e middle o f the spawning p e r i o d i n 1973, appeared to s t o p spawning ( F i g . 26). M o p a l i a l a e v i o r and M o p a l i a c i l i a t a spawned a b r u p t l y a t t h e o n s e t o f the p h y t o p l a n k t o n o u t b u r s t i n 1973, and more g r a d u a l l y i n .1974, c o r r e s p o n d i n g t o t h e slow i n c r e a s e i n 113 p h y t o p l a n k t o n i n t h a t y e a r . Spawning o f K a t h a r i n a t u n i c a t a a t B o t a n i c a l Beach was c l o s e l y t i med w i t h t h a t of T. l i n e a t a i n each y e a r d u r i n g 1971—197 4, and i n 1973 bo t h s p e c i e s o n l y spawned p a r t i a l l y i n A p r i l and completed spawning i n June. Spawning i n S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s a t B o t a n i c a l Beach i n 1973 was completed d u r i n g A p r i l . I i n d i c a t e d e a r l i e r t h a t the A p r i l 1973 p h y t o p l a n k t o n bloom i n Juan de Fuca S t r a i t was not as i n t e n s e as i n S t r a i t o f G e o r g i a (Table IV).,, The p a r t i a l spawning i n T. l i n e a t a and K. t u n i c a t a and the complete spawning i n S. d r o e b a c h i e n s i s c o i n c i d e d w i t h t h i s A p r i l p h y t o p l a n k t o n bloom, and spawning i n T. l i n e a t a and K. t u n i c a t a was completed i n June when a second and more i n t e n s e bloom occurred,,, A l t h o u g h p h y t o p l a n k t o n o b s e r v a t i o n s were not made d u r i n g o t h e r y e a r s a t B o t a n i c a l Beach, the synchrony of spawning i n X. . l i n e a t a . and K. t u n i c a t a s u g g e s t s t h a t t h e s e two s p e c i e s were r e s p o n d i n g t o the same s t i m u l u s . The synchrony of spawning by M o p a l i a l a e v i o r , M o g a l i a c i l i a t a and K a t h a r i n a t u n i c a t a w i t h p h y t o p l a n k t o n blooms i n the ye a r s when.there were d a t a on the t i m i n g of t h e bloom, and the c l o s e t i m i n g of spawning i n t h e s e s p e c i e s w i t h spawning i n S t r o n g y i o c e n t r o t u s d r o e b a c h i e n s i s . T o n i c e l l a l i n e a t a and T o n i c e l l a i n s i g n i s i n years when t h e r e were no d a t a a v a i l a b l e on p h y t o p l a n k t o n , s u g g e s t s t h a t t h e p h y t o p l a n k t o n bloom was a l s o the cue f o r spawning i n M. l a e v i o r , £iAi§.ta a n d K. t u n i c a t a . However, t h i s a s sumption r e g u i r e s e x p e r i m e n t a l e v i d e n c e , , Spawning by the o t h e r s p e c i e s i n the p r e s e n t s t u d y d i d not appear t o c o i n c i d e w i t h t h e s p r i n g p h y t o p l a n k t o n blooms,, At F i r s t Marrows Mo£alia h i n d s i i spawned i n the w i n t e r i n 1973 and 114 j u s t p r i o r t o t h e bloom i n 1973. I n M o p a l i a muscosa, spawning was not synchronous f o r a n i m a l s i n d i f f e r e n t p o o l s a t B o t a n i c a l Beach and t h e r e f o r e was p r o b a b l y not r e l a t e d t o a w i d e s p r e a d f a c t o r l i k e t h e p h y t o p l a n k t o n bloom. I n M o p a l i a l i g n o s a t h e r e appeared t o be spawning b e f o r e the bloom i n 19 73 and a n o t h e r spawning d u r i n g t h e summer., The slow spawning i n S t r o n g y l o c e n -t r o t u s p u r p u r a t u s was i n marked c o n t r a s t t o t h e o t h e r s p e c i e s . I t seems u n l i k e l y t h a t i t uses p h y t o p l a n k t o n a s a cue f o r spawning. Thus, M o p a l i a h i s g s i i , M o p a l i a muscosa, M o p a l i a l i g n o s a and S t r o n g y l o c e n t r o t u s p u r p u r a t u s p r o b a b l y do not use p h y t o p l a n k t o n as a s t i m u l u s f o r spawning., While p h y t o p l a n k t o n appears t o s t i m u l a t e spawning i n some of the s p e c i e s i n the p r e s e n t s t u d y , the i n f l u e n c e of o t h e r f a c t o r s cannot be e x c l u d e d . . I n t h e 1974 e x p e r i m e n t s , when p h y t o p l a n k t o n was added t o S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s and T o n i c e l l a l i n e a t a a t a temperature o f 5.5 °C, a s m a l l e r p r o p o r t i o n o f a n i m a l s c o l l e c t e d on 4 t h A p r i l spawned t h a n those c o l l e c t e d on 12th March. However, when the . e x p e r i m e n t a l t e m p e r a t u r e was 10 °C, a s i m i l a r p r o p o r t i o n o f T . , l i n e a t a from 12th March and 4 t h A p r i l spawned., F i e l d t e m p e r a t u r e s a t F i r s t Harrows (as measured a t the Vancouver P u b l i c Aguarium) a t 6 m below MLWS i n c r e a s e d 1 °C or l e s s between 12th March and 4 t h A p r i l . I t would appear t h a t l o w e r i n g the temperature i n h i b i t e d spawning, and t h a t once a n i m a l s have adapted t o warmer c o n d i t i o n s , even j u s t a s l i g h t t e m p e r a t u r e i n c r e a s e , t h e temperature l e v e l a t which spawning i s i n h i b i t e d i s i n c r e a s e d . D u r i n g t h e e x p e r i m e n t s on S. d r o e b a c h i e n s i s i t was f r e q u e n t l y observed t h a t spawning d i d not b e g i n when an a n i m a l was exposed 115 t o p h y t o p l a n k t o n , hut s t a r t e d when t h e water was b e i n g changed., [ A n i m a l s which spawned i n t h i s way were counted as p o s i t i v e r e s u l t s i n T a b l e V, s i n c e c o n t r o l s handled i n the same way d i d not spawn.] Changing t h e water caused a s l i g h t t e m p e r a t u r e change and m e c h a n i c a l a g i t a t i o n . I n t h r e e i n s t a n c e s i t was found t h a t the spawning began even when f r e s h s e a water was added v e r y s l o w l y , l o w e r i n g the t e m p e r a t u r e o n l y 2 °C. , An i m a l s exposed t o sperm responded i n the same way. Thus, i n S. dr o e -b a c h i e n s i s p h y t o p l a n k t o n and sperm seemed t o s e n s i t i z e t h e a n i m a l s so t h a t spawning i s provoked by a s l i g h t , d i s t u r b a n c e . , fthen d e t e r m i n i n g t h e gonadal i n d e x o f a n i m a l s from the f i e l d , a wet weight was r e c o r d e d a f t e r a l l o w i n g a n i m a l s t o d r a i n on paper t o w e l l i n g f o r 15 mi n u t e s , and the a n i m a l s were t h e n r e t u r n e d t o c o l d water., H a n d l i n g S. d r o e b a c h i e n s i s , • T . , l i n e a t a , and 2- i n s i g n i s i n t h i s way caused some i n d i v i d u a l s t o spawn, but o n l y when spawning was imminent i n the f i e l d . I n e a r l y June 1974 a few a n i m a l s spawned w i t h o u t p r e v i o u s exposure t o p h y t o p l a n k t o n . These a n i m a l s had been h e l d i n the l a b o r a t o r y a t 10 °C f o r a p r o l o n g e d p e r i o d . The synchrony o f spawning w i t h p h y t o p l a n k t o n blooms has been known f o r many y e a r s , Thorson (1936, 1946, 1951) emphasized t h a t p e l a g i c l a r v a e o f b e n t h i c s p e c i e s a r e u s u a l l y most abundant d u r i n g p h y t o p l a n k t o n blooms, whether i t be i n t h e A r c t i c where a s i n g l e bloom p e r i o d o c c u r s , or i n temperate s e a s where t h e r e may be s p r i n g , summer and autumn blooms., I n Thorson*s time t h e r e was much emphasis on the i m p o r t a n c e o f temperature i n c o n t r o l l i n g b i o l o g i c a l p r o c e s s e s , i n c l u d i n g spawning. However, Thorson (1946) c l e a r l y s t a t e d t h a t i t cannot 116 be e x c l u d e d t h a t p h y t o p l a n k t o n a c t s t o s t i m u l a t e spawning. I n G r e e n l a n d , spawning and p h y t o p l a n k t o n blooms may o c c u r b e f o r e t h e r e i s a r i s e i n t e m p e r a t u r e (Thorson, 1936)., T h i s synchrony i s not l i m i t e d t o b e n t h i c s p e c i e s f o r i t has a l s o been o b s e r v e d i n p e l a g i c a n i m a l s , f o r example euphausids ( E i n a r s s o n , 1945) and c a l a n o i d copepods ( M a r s h a l l , N i c h o l l s & O r r , • 1934)., At I g l o o l i k , i n the Canadian A r c t i c , G r a i n g e r (1959) n o t e s t h a t t h e young of h e r b i v o r o u s zooplank'ton s p e c i e s become abundant a t the t i m e of the summer p h y t o p l a n k t o n i n c r e a s e , and i n some s p e c i e s t h i s may occur b e f o r e t h e r e i s warming of even t h e s u r f a c e waters. Barnes (1957), and Barnes and Stone (197 3) r e p o r t t h a t the r e l e a s e o f n a u p l i i by some b a r n a c l e s i s s t i m u l a t e d by t h e s p r i n g diatom o u t b u r s t , and emphasize the i m p o r t a n c e o f t h i s s ynchrony f o r a l l a n i m a l s w i t h p l a n k t o t r o p h i c l a r v a e , whether the eggs and sperm a r e r e l e a s e d d i r e c t l y i n t o the sea o r the e a r l i e r s t a g e s a r e n u r t u r e d by t h e a d u l t s and then r e l e a s e d . The advantages t o spawning a t t h e same time as t h e p h y t o p l a n k t o n bloom may v a r y a c c o r d i n g to the s p e c i e s . For a n i m a l s w i t h p l a n k t o t r o p h i c l a r v a e t h e a v a i l a b i l i t y of f o o d i s of o b v i o u s i m p o r t a n c e . The l a r v a e o f S. d r o e b a c h i e n s i s a r e p e l a g i c f o r 2.5 months (fiunnstrom, 1927b) t o 6 weeks (St r a t h m a n , p e r s . comm.), but f e e d i n g cannot b e g i n u n t i l the p l u t e u s d e v e l o p s , which t a k e s more than a week (Stephens, 1972). Strathmann (1971) o f f e r e d n a t u r a l p h y t o p l a n k t o n t o 8-armed p l u t e i and found t h a t they c o u l d i n g e s t p a r t i c l e s as l a r g e as armoured d i n o f l a g e l l a t e s measuring SO x 60 x 40 jx. „ S h o r t c h a i n s °f Skeletonema costatum and T h a l l a s s i o s i r a sp., were found i n t h e stomachs of l a r v a e , and t h e r e was e v i d e n c e t h a t diatoms were 117 e a s i l y d i g e s t e d , Skeletonema costatum and T h a i l a s s i o s i r a spp, were i m p o r t a n t elements of the blooms i n 1973 and 1974 {Table I I , I I I , and V). L o o s a n o f f and D a v i s {1963) i n d i c a t e d t h a t f o o d and t e m p e r a t u r e were v e r y i m p o r t a n t f a c t o r s i n t h e growth of a number of b i v a l v e l a r v a e . , The f o o d r e q u i r e m e n t s v a r i e d f o r d i f f e r e n t b i v a l v e s p e c i e s and f o r d i f f e r e n t d e v e l o p m e n t a l s t a g e s w i t h i n a s i n g l e s p e c i e s , , They s t a t e d t h a t d i n o f l a g e l l a t e blooms cause abnormal development and h i g h m o r t a l i t y to b i v a l v e l a r v a e . , I n c h i t o n s , the egg i s l a r g e and u s u a l l y d e v e l o p s i n t o a f r e e swimming t r o c h o p h o r e , which a f t e r a s h o r t p e r i o d s e t t l e s and metamorphoses d i r e c t l y i n t o t h e a d u l t form (see d e s c r i p t i o n s o f l a r v a l development by B a r n e s , 1972; Barnes & Gonor, 1973; Watanabe & Cox, 1975). The c h i t o n s p e c i e s which use p h y t o p l a n k t o n as a spawning cue a l m o s t c e r t a i n l y spend t h e i r e n t i r e p e l a g i c e x i s t e n c e under bloom c o n d i t i o n s , but t h e y p r o b a b l y do not e a t p h y t o p l a n k t o n . P o s s i b l y o t h e r f a c t o r s a r e advantageous f o r c h i t o n l a r v a e . The s p r i n g p h y t o p l a n k t o n bloom i s one o f the most s h a r p l y d e f i n e d e v e n t s i n temperate and p o l a r seas and t h i s a l o n e would make i t a r e l i a b l e spawning cue t o ensure f e r t i l i z a t i o n . The eggs of T. l i n e a t a and I . i n s i g n i s can e a s i l y be d i s p e r s e d by water c u r r e n t s and Barnes (1972) r e p o r t e d t h a t T. ...lineata eggs do not d e t e r i o r a t e f o r a t l e a s t 14 h. H y d r o g r a p h i c c o n d i t i o n s a t t h e time o f t h e s p r i n g p h y t o p l a n k t o n bloom a r e d e s c r i b e d by Sverdrup {1953). D u r i n g the w i n t e r t h e r e i s a m i x i n g of t h e water column t o a g r e a t d e p t h , but as s p r i n g approaches t h e depth o f t h i s mixed l a y e r d e c r e a s e s due t o h e a t i n g a t the s u r f a c e or t o t h e f o r m a t i o n o f a 118 l e s s s a l i n e t o p l a y e r . , The bloom o c c u r s when the depth of t h e mixed s u r f a c e l a y e r i s l e s s than t h e c r i t i c a l depth where p r o d u c t i o n due t o p h o t o s y n t h e s i s exceeds d e s t r u c t i o n due t o r e s p i r a t i o n . , L i g h t p e n e t r a t i o n and i n t e n s i t y i n f l u e n c e t h e depth o f t h i s c r i t i c a l l e v e l . L a r v a e r e l e a s e d d u r i n g t h e bloom ar e l i k e l y t o s t a y i n t h i s s u r f a c e l a y e r . , Here t e m p e r a t u r e s a r e u s u a l l y warmer t h a n a t g r e a t e r depths and i n most s p e c i e s t h i s i n c r e a s e s the growth r a t e of t h e l a r v a e . , S i n c e so many s p e c i e s spawn d u r i n g t h e p h y t o p l a n k t o n bloom, the t o t a l amount of p r e d a t i o n may be l e s s per s p e c i e s t h a n i f d i f f e r e n t s p e c i e s were to a l t e r n a t e t h e i r spawning. Even though p h y t o p l a n k t o n may not be used as f o o d f o r some p e l a g i c l a r v a e , the i n c r e a s e i n p r o d u c t i o n o f b e n t h i c a l g a e , a t about the same t i m e as t h e bloom, may be i m p o r t a n t as f o o d f o r r e c r u i t i n g b e n t h i c o r g a n i s m s . , A l s o o r g a n i c matter s e t t l i n g from the bloom may be a u s e f u l f o o d s o u r c e f o r young a n i m a l s . I n t e r n a l C o n s i d e r a t i o n s In t h e p a s t decade t h e r e have been numerous s t u d i e s on e n d o c r i n e mechanisms i n i n v e r t e b r a t e s , and i t i s becoming i n c r e a s i n g l y c l e a r t h a t they p l a y an i m p o r t a n t r o l e i n t h e r e p r o d u c t i v e b i o l o g y o f marine i n v e r t e b r a t e s (see r e v i e w s by Highman £ H i l l , 1969; G o u l d i n g , 1972; f i n g e r m a n , 1974). For example, some e n d o c r i n e c o n t r o l mechanisms have been worked out i n echinoderms. Chaet and McConnaughy (1959) f i r s t r e p o r t e d t h a t spawning i n s t a r f i s h c o u l d be i n d u c e d when a s u b s t a n c e from the r a d i a l nerve i s i n j e c t e d i n t o t h e coelom. Numerous o t h e r 119 s t u d i e s have f u r t h e r e l u c i d a t e d t h e mechanism of s t a r f i s h spawning ( K a n t a n i £ S k i r a i , 1972), A p o l y p e p t i d e produced by nervous t i s s u e , when r e l e a s e d i n t o the coelom, c a u s e s t h e o v a r i e s t o produce a second s u b s t a n c e , 1-methyiadenine. , The l a t t e r s u b s t a n c e i n d u c e s o o c y t e m a t u r a t i o n , d i s s o l v e s t h e attachment of t h e o o c y t e s to t h e f o l l i c l e s , and c a u s e s the o v a r i a n w a l l t o c o n t r a c t , t h e r e b y r e s u l t i n g i n the r e l e a s e of gametes. Other s u b s t a n c e s have been found which b l o c k m e i o s i s and i n h i b i t spawning, and t h u s p r e v e n t t h e r e l e a s e o f gametes b e f o r e t h e a p p r o p r i a t e time (Ikegami & Tamura, 1973) . .. I n t h e u r c h i n , S t r o n g y l o c e n t r p t u s p u r g u r a t u s , i t has been demonstrated t h a t the c o n c e n t r a t i o n o f a n e u r a l s u b s t a n c e which i n d u c e s spawning f l u c t u a t e s w i t h t h e r e p r o d u c t i v e c y c l e (Cochran & Engelmann, 1972)., Thus, i f e x t e r n a l f a c t o r s a f f e c t r e p r o d u c t i o n , t h e y a r e l i k e l y mediated by e n d o c r i n e pathways., U n f o r t u n a t e l y , t h e m a j o r i t y o f e n d o c r i n o l o g i c a l s t u d i e s have n o t c o n s i d e r e d the i n f l u e n c e o f e x t e r n a l f a c t o r s on t h e s e i n t e r n a l c o n t r o l mechanisms. As mentioned e a r l i e r , i n some v e r t e b r a t e s i t has been shown t h a t p h o t o p e r i o d a c t i n g t h r o u g h a n e u r o e n d o c r i n e pathway c o o r d i n a t e s s e a s o n a l r e p r o d u c t i v e a c t i v i t y . A number of r e s e a r c h e r s have proposed t h a t p h o t o p e r i o d may a l s o i n f l u e n c e e n d o c r i n e systems which r e g u l a t e r e p r o d u c t i v e c y c l e s i n marine i n v e r t e b r a t e s ( S e l l s £ H e l l s , 1959; H a u e n s c h i l d , 1964; A d i y o d i £ A d i y o d i , 1970; G o l d i n g , 1972). T h i s s h o u l d be f u r t h e r i n v e s t i g a t e d . Some i n t e r n a l e v e n t s , once i n i t i a t e d , might p r o c e e d w i t h o u t 120 f a r t h e r c o o r d i n a t i o n from the e x t e r n a l environment. .. T h i s was suggested f o r p o r t i o n s o f the gametogenic seguence i n b a r n a c l e s ( C r i s p & P a t e l , 1969). A l s o endogenous sequences have been suggested t o p l a y a r o l e i n r e p r o d u c t i v e c y c l e s of a n i m a l s l i v i n g under n e a r l y c o n s t a n t e n v i r o n m e n t a l c o n d i t i o n s ( P e a r s e , 1965: H o l l a n d , 1967), In some l a m e l l i b r a n c h s , spawning may not r e q u i r e an e x t e r n a l s t i m u l u s , but may happen s p o n t a n e o u s l y when gametogenic e v e n t s , which were i n i t i a t e d by i n c r e a s e d water t e m p e r a t u r e , a r e completed ( L o o s a n o f f and D a v i s , 1963; S a s t r y , 1966). Here spawning may not r e q u i r e an e x t e r n a l s t i m u l u s , but may happen s p o n t a n e o u s l y when the a n i m a l has r e a c h e d a c e r t a i n p o i n t i n development. A l t e r n a t i v e l y , i n t e r n a l mechanisms may change the c o n d i t i o n o f the a n i m a l so t h a t any s l i g h t d i s t u r b a n c e w i l l c ause spawning. Once gametes a r e i n t h e water o t h e r a n i m a l s w i l l be s t i m u l a t e d t o spawn (KecJces, O z r e t i c & Lucu, 1966).. B o o l o o t i a n (1964a, 1966) d e s c r i b e d an e x p e r i m e n t i n which a group of §tronqxlocent£otus purpurafeus were m a i n t a i n e d i n a c i r c u l a t i n g seawater s y s t e m , and y e t spawning o c c u r r e d a t t h e normal time over two c o n s e c u t i v e y e a r s . I t appears t h a t e x t e r n a l f a c t o r s may c o o r d i n a t e i n t e r n a l e v e n t s a t s p e c i f i c p o i n t s , and t h a t once i n i t i a t e d some r e p r o d u c t i v e seguences w i l l proceed w i t h o u t f u r t h e r c o o r d i n a t i o n by e x t e r n a l f a c t o r s . 121 E v o l u t i o n a r y and Geographic C o n s i d e r a t i o n s R e p r o d u c t i v e c y c l e s have e v o l v e d i n r e s p o n s e t o s e l e c t i v e p r e s s u r e s f o r i n c r e a s e d r e p r o d u c t i v e s u c c e s s . , I n marine i n v e r t e b r a t e s the e a r l y d e v e l o p m e n t a l and l a r v a l s t a g e s a r e most s e n s i t i v e t o adver s e p h y s i c a l c o n d i t i o n s (Runnstrom, 1 9 2 7 a ) , and t h e r e would be a d i s t i n c t advantage t o c o o r d i n a t i n g t h e s e phases w i t h f a v o u r a b l e c o n d i t i o n s . F u r t h e r , the a v a i l a b i l i t y o f f o o d i s i m p o r t a n t f o r s p e c i e s w i t h p l a n k t o t r o p h i c l a r v a e . ., Thorson (1946) demonstrated t h e i n c r e a s e d tendency of s p e c i e s i n p o l a r r e g i o n s t o brood t h e i r young and r e l a t e d t h i s t o t h e harsh p h y s i c a l c o n d i t i o n s and s h o r t p e r i o d s when food i s a v a i l a b l e to the l a r v a e . The s p e c i e s i n c o l d waters which have p e l a g i c l a r v a e u s u a l l y s y n c h r o n i z e t h i s phase w i t h p h y t o p l a n k t o n blooms, which a l s o may c o i n c i d e w i t h s l i g h t l y i n c r e a s e d t e m p e r a t u r e s . These s p e c i e s t y p i c a l l y d e v e l o p t h e i r gonads d u r i n g t h e w i n t e r so t h a t t h e gametes a r e ready f o r r e l e a s e - when t h i s s h o r t p e r i o d o f f a v o u r a b l e c o n d i t i o n s a r r i v e s . A l t e r n a t i v e l y , i f e a r l y development under t h e s e low t e m p e r a t u r e s i s very s l o w , spawning may o c c u r b e f o r e the bloom so t h a t t h e l a r v a e have r e a c h e d the f e e d i n g s t a g e and can make immediate use of the p h y t o p l a n k t o n when the bloom o c c u r s ( P e a r s e , 1965). I n warm s e a s , the m a j o r i t y of s p e c i e s have p e l a g i c l a r v a e and the d i f f e r e n t s p e c i e s spawn a t v a r i o u s (and sometimes s e v e r a l ) t i m e s d u r i n g the y e a r . Here, p l a n k t o n p r o d u c t i o n i s more or l e s s c o n s t a n t and t h e s c a t t e r e d spawning p e r i o d s p r o b a b l y d e c rease c o m p e t i t i o n f o r food among p l a n k t o t r o p h i c l a r v a e (Thorson, 1946, 1950). I n temperate seas t h e r e a r e s p e c i e s o f both warm and c o l d 122 water o r i g i n . ,, S p e c i e s of c o l d water o r i g i n spawn when t h e p h y t o p l a n k t o n f i r s t become abundant i n the s p r i n g . . T h e i r l a r v a l phase i s o f t e n i n t o l e r a n t t o warm c o n d i t i o n s , as i n t h e case o f S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s , and must be completed b e f o r e warm summer c o n d i t i o n s s e t i n {fiunnstrom, 1927a)., S p e c i e s o f warm water o r i g i n u s u a l l y d e v e l o p t h e i r gonads o n l y when t e m p e r a t u r e s r e a c h a c e r t a i n l e v e l i n t h e s p r i n g , or gonadal development may be s t a r t e d i n the autumn, a r r e s t e d i n t h e w i n t e r and resumed i n t h e s p r i n g . The l a r v a e o f t h e s e s p e c i e s cannot t o l e r a t e c o l d t e m p e r a t u r e s (fiunnstrom, 1927a), and spawning o c c u r s i n t h e summer and autumn. Spawning may be c o o r d i n a t e d w i t h the presence of c e r t a i n p h y t o p l a n k t o n f o o d s p e c i e s f o r the l a r v a e , o r w i t h r e d u c e d f e e d i n g a c t i v i t i e s of p r e d a t o r y a n i m a l s (Thorson, 1946, 1958).. The s p e c i e s of c o l d water o r i g i n u s u a l l y have s h o r t spawning p e r i o d s , w h i l e s p e c i e s o f warm water o r i g i n o f t e n have p r o l o n g e d p e r i o d s of gametogenesis and spawning. A l s o s i n c e a c e r t a i n t e m p e r a t u r e may be r e q u i r e d f o r r e p r o d u c t i o n i n warm water s p e c i e s t h e r e p r o d u c t i v e p e r i o d s a r e u s u a l l y d e l a y e d and s h o r t e n e d i n the c o l d e r p a r t s of t h e i r g e o g r a p h i c range ( O r t o n , 1920; Hopes & S t i c k n e y , 1965). S i m i l a r l y , a number o f s p e c i e s which e v o l v e d i n b o r e a l s e a s may have s h o r t e n e d r e p r o d u c t i v e p e r i o d s i n the warmer p a r t s o f t h e i r r a n g e , s i n c e g o n a d a l a c t i v i t y may cease when t e m p e r a t u r e s a r e too warm (Runnstrom, 1927a; Cochran & Engelmann, 1975). F o r c o l d water s p e c i e s t h e advantages o f spawning a t t h e t i m e of t h e p h y t o p l a n k t o n bloom (and i n c r e a s e d t e m p e r a t u r e s ) a r e u n d e r s t o o d a t l e a s t i n p a r t , but the advantages a s s o c i a t e d w i t h the v a r i a b l e spawning p e r i o d s i n warm water s p e c i e s a r e not c l e a r . , 123 The waters a l o n g t h e P a c i f i c c o a s t o f N o r t h A m e r i c a , from P o i n t C o n c e p t i o n , C a l i f o r n i a , northward t o the G u l f o f A l a s k a and westward a l o n g the A l a s k a n P e n i n s u l a , a r e c o o l and do not f l u c t u a t e g r e a t l y t h r o u g h o u t t h e year { l e s s than 10 °C annual v a r i a t i o n ) . S t r o n g y l o c e n t r o t u s d r o e b a c h i e n s i s i s a c i r c u m p o l a r s p e c i e s which e x t e n d s from the A r c t i c i n t o t h e N o r t h A l t a n t i c and N o r t h P a c i f i c . Throughout t h i s range i t d i s p l a y s t h e c o l d water r e p r o d u c t i v e p a t t e r n , w i t h g o n a d a l growth i n t h e w i n t e r and an a b r u p t spawning a t the time o f the f i r s t i n c r e a s e i n p h y t o p l a n k t o n . I t s l a r v a e cannot t o l e r a t e t e m p e r a t u r e s above 9-11 °C {fiunnstrom, 1927a; Stephens, 1972) and t h e s o u t h e r n g e o g r a p h i c a l l i m i t o f t h i s s p e c i e s i s p r o b a b l y d e t e r m i n e d by t h e t e m p e r a t u r e s r e a c h e d d u r i n g t h e bloom p e r i o d and s e v e r a l weeks l a t e r . S t r o n g y l o c e n t r o t u s p u r p u r a t u s i s endemic t o the n o r t h w e s t P a c i f i c and w h i l e the t i m i n g o f i t s g o n a d a l growth c o i n c i d e s w i t h t h a t i n S. d r o e b a c h i e n s i s , i t s spawning p a t t e r n i s s t r i k i n g l y d i f f e r e n t . R e p r o d u c t i o n has been s t u d i e d i n S. EM££M£§l=iiI> more tha n any o t h e r s p e c i e s on t h e P a c i f i c c o a s t , but t h e f a c t o r s c o n t r o l l i n g i t s w i n t e r — s p r i n g spawning a r e not known. , The genus T o n i c e l l a a l s o o c c u r s i n the A r c t i c and e x t e n d s i n t o the North P a c i f i c and N o r t h A t l a n t i c . D a l l (1878, 1921) r e p o r t e d t h a t T o n i c e l l a l i n e a t a r a n g e s from n o r t h e r n Japan and the Okhotsk Sea n o r t h w a r d t o the B e r i n g Sea, t h r o u g h o u t the A l e u t i a n s , a l o n g t h e A l a s k a n P e n i n s u l a and southward a l o n g t h e North American c o a s t t o San Diego. However, S i r e n k o (1973) c o n s i d e r e d the form on A s i a t i c s h o r e s t o be a s e p a r a t e s p e c i e s . 124 T o n i c e l l a i n s i g n i s has a narrow r a n g e , b e i n g r e p o r t e d o n l y from A l a s k a t o Puget Sound ( B u r g h a r d t s , 1969). Both T. l i n e a t a and 2* i n s i g n i s showed an i n c r e a s e i n gonadal s i z e from t h e summer th r o u g h t h e w i n t e r and spawning was s t i m u l a t e d by t h e s p r i n g p h y t o p l a n k t o n bloom. I n T. l i n e a t a t h e r e was e v i d e n c e t h a t spawning was i n h i b i t e d i f t e m p e r a t u r e s of 7-8 °C a r e n o t reached a t t h e time o f t h e bloom. Thus, T. l i n e a t a and T, i n s i g n i s a l s o d i s p l a y t h e r e p r o d u c t i v e p a t t e r n which i s c h a r a c t e r i s t i c o f c o l d water s p e c i e s . The genus M o p a l i a o c c u r s o n l y i n the North P a c i f i c and t h e r e has been e x t e n s i v e s p e c i a t i o n i n t h i s genus on No r t h American s h o r e s . M o p a l i a muscosa and M o p a l i a c i l i a t a a r e t h e most wide s p r e a d , o c c u r r i n g a l o n g t h e A l a s k a n P e n i n s u l a and southward t o B a j a C a l i f o r n i a ( B a l l , 1878, 1921; B e r r y , 1922). M o p a l i a l i g n o s a and M o p a l i a h i j i d s i i e x t e n d from S i t k a , A l a s k a , t o the s o u t h e r n p a r t o f B a j a C a l i f o r n i a p e n i n s u l a ( B a l l , 1921), w h i l e M o p a l i a l a e v i o r i s known o n l y from S i t k a { B u r g h a r d t s , 1969) t o c e n t r a l C a l i f o r n i a ( R i c e , 1971). These s p e c i e s e x h i b i t e d v a r i o u s r e p r o d u c t i v e p a t t e r n s . , M. h i n d s i i spawned when t e m p e r a t u r e s were near t h e an n u a l minimum or had j u s t warmed s l i g h t l y , and M . . c i l i a t a and M. l a e v i o r spawned a t the time of the s p r i n g p h y t o p l a n k t o n increase.,. I n t h e s e t h r e e s p e c i e s gonadal growth u s u a l l y s t a r t e d i n the summer and c o n t i n u e d t h r o u g h t h e autumn and e a r l y w i n t e r . The d a t a f o r M o p a l i a l i g n o s a were l e s s c l e a r but gona d a l growth and spawning may have o c c u r r e d i n the l a t e w i n t e r as w e l l as i n t h e s p r i n g and summer., R e p r o d u c t i v e a c t i v i t y i n M. l u s e o s a p r o b a b l y o c c u r r e d t h r o u g h o u t the year and seemed t o v a r y i n t h e d i f f e r e n t 125 p o o l s where the a n i m a l s were f o u n d , r a t h e r t h a n w i t h more g e n e r a l e n v i r o n m e n t a l c o n d i t i o n s . , U n l i k e t h e o t h e r s p e c i e s i n t h i s s t u d y M. muscosa o c c u r s p r i m a r i l y i n the m i d - i n t e r t i d a l r e g i o n , and i s t h u s exposed t o more e r r a t i c changes i n e n v i r o n m e n t a l c o n d i t i o n s . Thus, s e v e r a l p a t t e r n s of r e p r o d u c t i v e a c t i v i t y a re found i n t h e genus M o p a l i a . K a t h a r i n a t u n i c a t a and another c h i t o n . C r y p t o c h i t o n s t e l l e r i , are known from t h e P l i o c e n e , and have a l o n g e r g e o l o g i c h i s t o r y than the o t h e r c h i t o n s i n t h i s study . ( B e r r y , 1922). Both genera a r e m o n o s p e c i f i c and show l i t t l e m o r p h o l o g i c a l v a r i a t i o n t h r o u g h o u t t h e i r e x t e n s i v e g e o g r a p h i c a l ranges., They a r e t h u s matured s p e c i e s (or e u s p e c i e s ) as d e f i n e d by D i l l o n (1966). C r y p t q c h i t g n s t e l l e r i o c c u r s from Hokodate i n n o r t h e r n Japan, on the K u r i l and S a k h a l i n I s l a n d s around t h e Okhotsk Sea, a t t h e s o u t h e r n e x t r e m i t y o f Kamchatka, i n t h e A l e u t i a n s , and a l o n g t h e A l a s k a n P e n i n s u l a and s o u t h t o s o u t h e r n C a l i f o r n i a ; and K. t u n i c a t a has a s i m i l a r d i s t r i b u t i o n e x c e p t t h a t i t i s found o n l y from Kamchatka on A s i a t i c s h o r e s ( D a l l , 1878, 1921). Both s p e c i e s showed l i t t l e g onadal growth d u r i n g t h e summer and r a p i d development i n t h e autumn and w i n t e r , but t h e i r spawning t i m e s are s e p a r a t e . I n t h e Monterey a r e a , even i n t h e same y e a r s , C r y p t q c h i t g n s t e l l e r i spawned i n l a t e w i n t e r t o e a r l y s p r i n g and K. t u n i c a t a spawned i n t h e l a t e s p r i n g t o e a r l y summer ( F i g . , 4 ; Tucker and G i e s e , 1962; Lawrence, Lawrence & G i e s e , 1965). However, i n Japan C r y j e t o c h i t o n s t e l l e r i was r e p o r t e d t o spawn i n May (Okuda, 1947). I n summary, a l l of t h e s p e c i e s i n t h e p r e s e n t s t u d y show 126 g o n a d a l growth d u r i n g t h e c o l d e r p a r t o f the y e a r . The ones w i t h s t r o n g a f f i n i t i e s t o A r c t i c forms spawn a t t h e t i m e o f t h e s p r i n g p h y t o p l a n k t o n bloom, and t h e p h y t o p l a n k t o n i t s e l f i s p r o b a b l y t h e spawning s t i m u l u s . Some o f t h e s p e c i e s which occur o n l y i n the temperate waters o f t h e n o r t h e a s t P a c i f i c spawn a t v a r i o u s t i m e s from w i n t e r t o e a r l y summer, and spawning i s pr o b a b l y c o n t r o l l e d by o t h e r f a c t o r s . None of the a n i m a l s i n t h i s s t u d y r e q u i r e i n c r e a s e d t e m p e r a t u r e s f o r gonadal growth as i s the p a t t e r n i n warm water s p e c i e s . The p r e s e n t s t u d y has d e s c r i b e d t h e p a t t e r n o f r e p r o d u c t i v e e v e n t s i n e i g h t s p e c i e s o f c h i t o n s and two sea u r c h i n s i n B r i t i s h Columbia w a t e r s . While no e x p e r i m e n t a l o b s e r v a t i o n s were made on the f a c t o r s c o n t r o l l i n g gonadal g r o w t h , t h e c o r r e l a t i v e o b s e r v a t i o n s on g o n a d a l growth and e n v i r o n m e n t a l c o n d i t i o n s p r o v i d e a b a s i s on which hypotheses f o r e x p e r i m e n t a l s t u d i e s can be made. The e f f e c t of p h o t o p e r i o d and t e m p e r a t u r e on g o n a d a l development s h o u l d be i n v e s t i g a t e d . , S t r o n g y l o c e n -t r o t u s d r o e b a c h i e n s i s , T o n i c e l l a l i n e a t a , and T o n i c e l l a i n s i g n i s would be u s e f u l s p e c i e s f o r such s t u d i e s s i n c e they can be e a s i l y m a i n t a i n e d i n the l a b o r a t o r y , and t h e l a t t e r two s p e c i e s r e g u i r e o n l y a s m a l l amount o f l a b o r a t o r y s pace, w h i l e the synchrony of spawning and p h y t o p l a n k t o n blooms has been r e c o g n i z e d f o r many y e a r s , the p r e s e n t s t u d y on S.. d r o j s b j i c i d e n -i i S ' T. l i n e a t a . and T. i n s i j j n i s i s t h e f i r s t d e m o n s t r a t i o n t h a t p h y t o p l a n k t o n , i t s e l f , i s t h e cue f o r t h e r e l e a s e o f gametes. 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