Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The distribution of the life history stages of Calanus plumchrus Marukawa (Copepoda : Calanoida) in the… Gardner, Grant A. 1972

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1973_A6_7 G37.pdf [ 2.75MB ]
Metadata
JSON: 831-1.0101212.json
JSON-LD: 831-1.0101212-ld.json
RDF/XML (Pretty): 831-1.0101212-rdf.xml
RDF/JSON: 831-1.0101212-rdf.json
Turtle: 831-1.0101212-turtle.txt
N-Triples: 831-1.0101212-rdf-ntriples.txt
Original Record: 831-1.0101212-source.json
Full Text
831-1.0101212-fulltext.txt
Citation
831-1.0101212.ris

Full Text

C o f 3 « THE DISTRIBUTION OF THE LIFE HISTORY STAGES OF CALAMJS PLUMCHRUS MARUKAWA (COPEPODA:CALANOIDA) IN THE STRAIT OF GEORGIA by GRANT A. GARDNER A THESIS SUBMITTED T.N PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of ZOOLOGY and INSTITUTE OF OCEANOGRAPHY We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH October, 1972 COLUMBIA In presenting t h i s t h e s i s in p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r agree that permission f o r extensive copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission. Department The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8, Canada Date O C T JO ft 7 Z-i ABSTRACT The r e l a t i o n s h i p between Calanus plumchrus and hydrographic parameters has been investigated. The copepod i s associated with S t r a i t of Georgia bottom water from J u l y to January. This associa-t i o n i s not found i n the early developmental stages, which are present from February to July and are most commonly i n near surface waters. The onset of maturation and breeding precedes the spring phytoplankton bloom; some environmental parameters appear to function as cues to t h i s timing. The nature of these cues i s not c l e a r ; no s i n g l e parameter would seem to be capable of producing the observed e f f e c t . C_. plumchrus overwinters i n a state of arrested development s i m i l a r to diapause. i i ACKNOWLEDGEMENT S The assistance and guidance of Dr. A.G. Lewis during the course of t h i s study i s acknowledged. Miss M.S. Evans i s also thanked f o r providing access to b i o l o g i c a l data c o l l e c t e d by her between November 1970 and October 1971, at three of the st a t i o n s studied, and f o r o f f e r i n g assistance and suggestions invaluable to the successful execution of t h i s study. Appreciation i s extended to a l l of the students, f a c u l t y and s t a f f of the I n s t i t u t e of Oceanography, U.B.C., for t h e i r many h e l p f u l suggestions and assistance i n the c o l l e c t i o n and ana l y s i s of the data on which t h i s manuscript i s based. To the o f f i c e r s and crew of C.S.S. Vector and C.S.S. Parizeau goes s p e c i a l g r a t i -tude f o r t h e i r assistance i n the c o l l e c t i o n of data. The author i s also g r a t e f u l to Dr. T.G. Northcote and Dr. T.H. Carefoot f o r reading and c r i t i c i z i n g t h i s manuscript. i i i TABLE OF CONTENTS Page ABSTRACT i ACKNOWLEDGEMENTS i i TABLE OF CONTENTS i i i LIST OF TABLES . i v LIST OF FIGURES v INTRODUCTION 1 MATERIALS AND METHODS .' 7 FIELD 7 Survey Locations 7 Data C o l l e c t i o n 10 Data Treatment 12 EXPERIMENTAL 18 C o l l e c t i o n of Animals and Water 18 Experimental Procedure 19 RESULTS 21 General D i s t r i b u t i o n 21 L i f e Cycle 24 Hydrographic Data and T-S-P Results 27 Experimental Results 30 DISCUSSION 32 REFERENCES 47 iv LIST OF TABLES Table 1. Biological and hydrographic sampling depths at each station. Table 2. Subsample volume (ml), mean volume (X), and standard error (s). Table 3. 95% Confidence Limits Table 4. Comparison of actual count with count esti-mated from a subsample. Table 5. Experimental Conditions Table 6. Concentration of C-V's between January, 1971 and January, 1972. (Averaged over the entire water column). Table 7. Development through the first four cope-podite stages in 1971. (Concentration in no./m ). • • • • Page 11 14 14 15 18 23 27 V Page • • • • LIST OF FIGURES Figure 1. Calanus plumchrus Marukawa, F i f t h Cope-podite Stage, l a t e r a l view. Figure 2. Map showing s t a t i o n l o c a t i o n s (100 fathom contour marked with dotted Line) .... 8 Figure 3, T-S-P diagrams for Fra-1, Fra-2, Geo-1 a-d. and Ind-9. .... 17 Figure 4. Concentration with depth of a l l stages at Geo-1 from A p r i l , 1971 to A p r i l , 1972 22 Figure 5. Concentration of the copepodite stages between November, 1970 and August, 1971. 26 Figure 6. S a l i n i t y i s o l i n e s at Geo-1 during 1971. .... 29 Figure 7. Experimental Results. .... 31 1 INTRODUCTION Despite the existence of several studies dealing with Calanus  plumchrus Marukawa, l i t t l e research has been c a r r i e d out to determine the r e l a t i o n s h i p between the organism and i t s environment. In addition, the factors involved i n regulating the behaviour and d i s t r i b u t i o n of the organism i n l o c a l waters have only beenCcursorially) examined^ x Calanus plumchrus ( F i g . 1) i s an herbivorous calanoid copepod d i s t r i b u t e d widely i n the North P a c i f i c . I t was o r i g i n a l l y described as C_. tonsus Brady (Brady, 1883) and was d i f f e r e n t i a t e d from s i m i l a r calanoid copepods p r i m a r i l y by i t s large s i z e and by the lack of serra t i o n s on the i n s i d e edge of the coxopodites of the f i f t h p a i r of swimming legs. C_. tonsus, however, i s a southern hemisphere form and i t s d i s t r i b u t i o n i s not continuous with that of the northern form. Marukawa (1921) designated the North P a c i f i c form as C_. plumchrus, but Brodsky (1938) considered C_. plumchrus - as synonymous with C_. tonsus. Tanaka (1956b) resolved the confusion over the name of the species. Although he had previously r e f e r r e d to i t as C_. tonsus (Tanaka, 1954, 1956a), he concluded that the species was morphologically d i f f e r e n t from the southern hemisphere form, and upheld i t s designation as Calanus plumchrus Marukawa. Furthermore, J i l l e t (1968) agrees that they are d i s t i n c t species and has described behavioural d i f f e r e n c e s f o r the two forms. 2 Figure 1: Calanus plumchrus Marulcawa, F i f t h Copepodite Stage, l a t e r a l view 3 U n t i l Tanaka's work i n 1956, much of the l i t e r a t u r e confused SL m tonsus with C_. plumchrus and, hence, many d i s t r i b u t i o n records are u n r e l i a b l e . I t i s probable that some of Brady's specimens were a c t u a l l y C_. plumchrus. Wilson (1950) recorded C_. tonsus from a number of s t a t i o n s i n the North P a c i f i c and Bering Sea, but he was undoubtedly dealing with C_. plumchrus. Consequently, references to C_. tonsus p r i o r to 1956 must be interpreted with care to avoid the p o s s i b i l i t y of confusion over the species c i t e d . Generally, references to C_. tonsus i n the North P a c i f i c a c t u a l l y deal with Calanus plumchrus. The d i s t r i b u t i o n of C_. plumchrus coincides with that of the P a c i f i c Subarctic Water Mass (Hebard, 1966; Heinrich, 1968). The organism has been found south to 40°N, and as f a r north as the Bering Sea (Heinrich, 1968) and Point Barrow, Alaska (MacGinitie, 1955), but i t s range apparently does not extend as f a r as the Beaufort Sea (Johnson, 1956). L o c a l l y , i t has been described i n the S t r a i t of Georgia by numerous authors, notably Campbell (1929a, b, 1930, 1933, 1934). The species i s extremely important economically. In the North P a c i f i c , i t i s a valuable food source f o r Sei whales (Nemoto, 1963; Foerster, 1968) . I t i s also grazed by the Right whale (Omura eit al_. , 1969) . During spring and summer i n the S t r a i t of Georgia, i t forms the dominant zooplankton species with respect to biomass, and i s the major food source for young salmon entering the S t r a i t en route to the open ocean (Campbell, 1933; LeBrasseur et a l . , 1969). 4 The l i f e cycle of C^, plumchrus has been described by numerous authors (Campbell, 1934; Brodsky, 1938; Heinrich, 1961, 1962a, 1968; Minoda, 1971; Pandyan, 1971) and i t s morphology has been treated i n d e t a i l by Campbell (1934) who ref e r r e d to i t as Calanus tonsus Brady. Because breeding occurs annually i n the spring, preceding the onset of the spring phytoplankton bloom, C_. plumchrus may be placed in"Category 2" of Heinrich's breeding types (Heinrich, 1962b). The coincident d i s t r i b u t i o n of C_. plumchrus and the P a c i f i c Subarctic Water Mass suggests that the d i s t r i b u t i o n of the organism may be r e l a t e d to hydrcgraphic properties. The r e l a t i o n s h i p between water types and plankton has been extensively investigated. The d i v i s i o n of the oceans i n t o large, d i s c r e t e bodies c a l l e d water masses, which are i d e n t i f i a b l e on the basis of temperature and s a l i n i t y (T-S) charac-t e r i s t i c s , i s accepted p r a c t i c e (Helland-Hansen, 1916; Sverdrup, Johnson and Fleming, 1942; Pickard, 1963). Zooplankton species and species groups have been described as c h a r a c t e r i s t i c of p a r t i c u l a r water masses ( B i e r i , 1959; McGowan, 1960; Aron, 1962; Fager and McGowan, 1963; Jaschnov 1961, 1963, 1970) and have been used as i n d i -cators of water of a p a r t i c u l a r o r i g i n . On a smaller s c a l e , species-water type r e l a t i o n s have been used to c l a r i f y water movements i n spe-c i f i c regions (Russell, 1935, 1939; Red f i e l d and Beale, 1940; Sherman and Schaner, 1968). An extensive examination of the r e l a t i o n s h i p be-tween species and water bodies was ca r r i e d out by Bary (1963a, b, c, 1964) who described the a s s o c i a t i o n between surface waters and species 5 groups i n the North A t l a n t i c west of the B r i t i s h I s l e s . He found d i s t i n c t r e l a t i o n s h i p s between species groups and three types of water—North, South, and T r a n s i t i o n a l — w h i c h could be d i f f e r e n t i a t e d on the basis of T-S c h a r a c t e r i s t i c s . Bary did not consider e i t h e r temperature or s a l i n i t y to be the environmental parameter to which the organisms were responding. He postulated that c e r t a i n other fa c t o r s were associated with the water bodies and that i t was these f a c t o r s which c o n t r o l l e d the occurrence of planktonic organisms. Attempts to i d e n t i f y the hypothetical f a c t o r s have not been suc-c e s s f u l , although i t has been demonstrated that the r e l a t i o n s h i p between organics, p a r t i c u l a t e s , and trace metals i n seawater can a f f e c t the s u r v i v a l of c e r t a i n zooplankton species (Johnson, 1964; Barber and Ryther, 1969; Lewis and Ramnarine, 1969; Lewis, Ramnarine and Evans, 1971). This phenomenon may w e l l be important i n re g u l a t i n g d i s t r i b u t i o n under c e r t a i n conditions. Chemical factors are not the only environmental parameters which regulate zooplankton d i s t r i b u t i o n . P h y s i c a l f a c t o r s such as water movements and l i g h t , as w e l l as b i o l o g i c a l f a c t ors such as pre-dation and food a v a i l a b i l i t y , are undoubtedly important. In view of the economic importance of Calanus plumchrus and the lack of s p e c i f i c information on i t s i n t e r a c t i o n s with the environ-ment, a study was i n i t i a t e d to examine the water body r e l a t i o n s of C_. plumchrus and to i n v e s t i g a t e the e f f e c t on the copepod of c e r t a i n of the environmental factors to which i t i s exposed. In p a r t i c u l a r , 6 the study was designed to examine the e f f e c t of these factors on the d i s t r i b u t i o n and breeding of the organism. 7 MATERIALS AND METHODS FIELD Survey Locations Five stations were selected f o r t h i s survey (Fig. 2). They are a l l estuarine i n nature and represent varying degrees of i s o l a t i o n from the open ocean and of exposure to fr e s h water runoff. Ind-9 (49°23.5'N, 122°52.5'W) Indian Arm i s a long, fjord-type i n l e t p a r t i a l l y separated from Burrard I n l e t to the south by 30 m deep s i l l . The i n l e t i s strongly influenced by fresh water runoff from the Indian River and i s e s s e n t i a l l y a two-layered system. Aspects of i t s physiography, c i r c u l a t i o n and hydrographic c h a r a c t e r i s t i c s have been extensively discussed by Gilmartin(1964). The i s o l a t i o n of t h i s i n l e t from the S t r a i t of Georgia, i n conjunction with the a v a i l a b i l i t y of recent survey data from the area (Woodhouse, 1971; Anon.j1971, 1972) made the i n l e t e s p e c i a l l y s u i t a b l e f or the present study. Boundary Pass (BP) (48°50.1'N, 122°57.4'W) This s t a t i o n has also been studied r e c e n t l y (Anon,,1971, 1972). Situated i n the southern part of the S t r a i t of Georgia, i t i s one of the major passages by which oceanic water enters the S t r a i t , and i s one of the areas -in which outflow from the Fraser River mixes with incoming oceanic water from the P a c i f i c Subarctic Water Mass (as 8 F i g u r e 2: Map showing s t a t i o n l o c a t i o n s (100 f a t h o m c o n t o u r marked w i t h d o t t e d l i n e ) . 9 defined by Hebard, 1966) and forms S t r a i t of Georgia bottom water (Waldichuk, 1957). The involvement with t h i s mixing process and the combined influence of oceanic and plume waters made i n c l u s i o n of t h i s s t a t i o n highly d e s i r a b l e . Geo-1 (49°17.0'N, 123°50.5'W) Again, previous data from t h i s s t a t i o n was a v a i l a b l e (Lewis, Ramnarine and Evans, 1971; Anon.,1971, 1972). The primary advantage however, was i t s depth. Previous information (Campbell, 1934; Pandyan, 1971) suggested that C_. plumchrus was found i n deep water, and t h i s s t a t i o n i s situated i n one of the deepest areas of the S t r a i t of Georgia. A v a i l a b l e b i o l o g i c a l samples also indicated that large num-bers of C_. plumchrus were found at t h i s s t a t i o n and thus i t was con-sidered important for the proposed study. Fra-1 (49°14.0'N; 123°22.5'W) and Fra-2 (49°01.3'N, 123°18.5'W) A v a i l a b l e l i t e r a t u r e on the Fraser River Plume (Parsons, Stephens and LeBrasseur, 1969; Parsons, LeBrasseur et a l . , 1969; LeBrasseur et a l . , 1969) consists p r i m a r i l y of production studies over short time periods and does not include many of the parameters with which the present study i s concerned. Both Fra-1 and Fra-2 were chosen p r i m a r i l y to determine i f Fraser River outflow a f f e c t s the d i s t r i b u t i o n and l i f e cycle of C. plumchrus. Fra-1, at 250 m, i s the deepest of the two st a t i o n s while Fra-2, at 190 m, i s much shallower. The two statio n s are out of the plume when runoff i s minimal. However, 10 maximum runoff coincides with early development of the copepod and during heavy runoff both stations are i n the plume. They are both e s s e n t i a l l y two-layered when runoff i s high, but provide a contrast with the Indian Arm s t a t i o n i n that c i r c u l a t i o n i s not as r e s t r i c t e d and the surface layer moves much more f r e e l y . The heavy amounts of s i l t i n the Fraser outflow provide a further contrast. Besides depth, the two s t a t i o n s d i f f e r i n exposure to runoff. Fra-1 i s most strongly influenced by the north arm of the Fraser River, while Fra-2 i s under the influence of the south arm. Data C o l l e c t i o n The f i v e stations were sampled at l e a s t once each month for a period of twenty months commencing November, 1970. At each s t a t i o n , h o r i z o n t a l tows were done at prearranged depths (Table 1) using Clarke-Bumpus opening/closing samplers (C-B nets). The samplers were equipped with flowmeters for determination of volume of water f i l t e r e d per tow, and were towed open for 15 minutes at a speed s u f f i c i e n t to maintain a wire angle of 35 ± 5° to the v e r t i c a l (ca. 2 knots). A v e r t i c a l haul was taken at each s t a t i o n from the depth of the deepest h o r i z o n t a l tow to the surface, using a c o n i c a l r i n g net having a 70 cm mouth d i a -meter and equipped with a 34 cm c y l i n d r i c a l metal c o l l a r . No. 2 mesh (ca. 0.3 mm aperture width) was used i n both types of net f o r most of the survey period. No. 10 mesh (ca. 0.1 mm aperture width) was used on the C-B nets from February to May, 1972, i n order to better 11 TABLE 1: B i o l o g i c a l and hydrographic sampling depths at each s t a t i o n . Ind-9 Fra-1 Fra-2 BP Geo-1 0* 10 20* 30 50 75 100 125 150 175 200 0* 0* 0* 10 20* 30 50 75 100 125 150 175 200 0* 10 20 30 50 75 100 125 150 175 200 10 20 30 50 75 100 125 135 150 165 10 20* 30 50 75 100 150 200 250 300 350 375 390 225** * denotes depth at which hydrographic data only was c o l l e c t e d . ** t h i s depth added i n November, 1 9 7 1 . NB: A l l depths are i n meters, 0 m denotes bucket sample. ensure the c o l l e c t i o n of eggs and naupliar stages. Both types of net were equipped with metal cod ends bearing mesh windows (aperture width as i n netting) through which water could drain, concentrating the sample. Samples from the C-B nets were trans-f e r r e d to 4 oz. screw-top glass j a r s , while the v e r t i c a l hauls were transferred to 1 6 oz. j a r s . Samples were preserved by the immediate a d d i t i o n of approximately 3-5% C^/\J) of formalin buffered with Borax (Na2B^0^'10 H^O). Nets were washed between hauls to prevent contamina-t i o n of l a t e r samples with animals retained i n the mesh and also to clean the netti n g . 12 Hydrographlc data were c o l l e c t e d from set depths (Table 1) using National I n s t i t u t e of Oceanography (NIO) sampling b o t t l e s . Water samples were drawn immediately f o r shipboard determination of dissolved oxygen concentration using a modified Winkler method ( C a r r i t t and Carpenter, 1966). Temperatures were read from reversing thermome-ters mounted i n frames on the sampling b o t t l e s , and water samples were drawn f o r s a l i n i t y determination i n the laboratory. A surface sample was obtained with a bucket for a surface s a l i n i t y sample and for the determination of temperature with an ordinary mercury thermometer gra-duated i n tenths of a centigrade degree. Graduations of 0.1 C were considered adequate since short term f l u c t u a t i o n s i n temperature are maximal near the surface, and temperatures read to 0.01 C are too p r e c i s e f or the degree of v a r i a t i o n involved. A bathythermograph (BT) cast was also done at each s t a t i o n to the depth of the deepest b o t t l e (or to 275 m, whichever was l e a s t ) . The BT was used to check temperature f l u c t u a t i o n s shown by the b o t t l e cast, to i n t e r p o l a t e temperature pro-f i l e s between b o t t l e depths, and to determine the depth of the thermo-c l i n e . Data Treatment Each 4 oz. preserved plankton sample was sorted, using a Wild M5 Stereomicroscope, and a l l specimens of Calanus plumchrus were removed, counted according to stage of development, and placed i n 2 dram screw-top v i a l s which were then placed i n s i d e the 4 oz. j a r from which the 13 animals came. Occasionally, the number of C_. plumchrus i n the sample was large enough to require sub-sampling. In such cases, a l l large organisms (euphausiids, chaetognaths, pasiphaeids, small f i s h , siphono-phores, medusae, and organisms of s i m i l a r size) were removed and the sample was made up to approximately 1 0 0 ml. A Folsom Plankton S p l i t t e r (McEwen, Johnson and Folsom, 1 9 5 4 ) , modified by the d i v i s i o n of the r o t a t i n g drum into four compartments, was used to divide the sample into four equal a l i q u o t s of which only one was analyzed. The sub-sample count was converted to estimated t o t a l count by a m u l t i p l i c a t i o n factor of 4 . On rare occasions when i t was necessary to take a 1/8, 1/16 or smaller sub-sample, s e r i a l sub-sampling was done with the same apparatus. To obtain an estimate of the error involved i n the method of sub-sampling, a s e r i e s of ten tests was performed. 1 0 0 ml a l i q u o t s of water were s p l i t and sub-sample volumes were calculated f o r each of the four c o l l e c t i n g trays (A, B, C, D). Mean and standard er r o r were c a l -culated f or each tray. These r e s u l t s are presented i n Table 2 . 9 5 % confidence l i m i t s were then calculated (Table 3 ) using equation 1: $ x $ X + t. X " t0.05 V10 '0.05 V10 (eqn. 1) NB: tg QJ- ( = 2 . 2 6 ) i s extracted from tables for the d i s t r i b u t i o n of t (Two-tailed tests) with (n-1) degrees of freedom (Snedecor and Cochran, 1 9 6 7 ) . !x' represents the expected subsample volume ( 9 5 % p r o b a b i l i t y ) . 14 TABLE 2: Subsample volume (ml), mean volume (X), and standard error ( s ) . A B C D 1 23.5 24.5 25.0 26.0 2 23.5 24.2 24.8 26.6 3 23.0 24.0 25.4 27.3 4 23.5 24.0 25.0 26.5 5 24.0 23.5 25.0 27.0 6 23.5 24.5 25.0 26.5 7 24.0 24.5 24.8 26.0 8 23.8 24.4 24.7 26.0 9 23.8 24.4 25.0 26.3 10 23.9 24.3 25.0 26.2 T o t a l 286.5 242.3 249.7 264.4 X 23.65 24.23 24.97 26.44 s ±0.31 ±0.36 ±0.19 ±0.47 TABLE 3: 95% Confidence L i m i t s A B C D UPPER 23.87 24.49 25.11 26.78 LOWER 23.65 23.97 24.83 26.10 Only tray C c o n s i s t e n t l y produced a sub-sample that did not deviate s i g n i f i c a n t l y from the i d e a l (25.00 ml). Consequently, i t was decided that only t h i s tray would be counted for the purpose of sub-sampling. Two tes t s using ac t u a l samples were performed as a check on the v a l i d i t y of sub-samples taken from t h i s tray. In both cases, the d e v i a t i o n between the estimated count and the ac t u a l count was n e g l i g i b l e (Table 4). 15 TABLE 4:* Comparison of actual count with count estimated from a sub-sample TEST SUB-SAMPLE COUNT ESTIMATED COUNT TRUE COUNT DEVIATION 1 36 144 142 +2 2 41 164 167 -2 A l l counts were recorded as t o t a l numbers and as d e n s i t i e s per cubic meter of each growth stage at each depth. Counts of females were further sub-divided according to breeding condition. Three conditions were recognized: mature (adult female, opaque and e i t h e r f u l l of eggs or with oviducts not yet developed, the l a t t e r condition being compara-t i v e l y r a r e ) , r i p e (transparent with large numbers of eggs i n the o v i -duct) and spent (transparent with obvious gaps between eggs i n the o v i -duct or a l l eggs gone). Conductivity of the s a l i n i t y samples was determined at IOUBC using an Auto Lab i n d u c t i v e l y coupled salinometer (model 601, MK I I I ) , and condu c t i v i t y was then converted to the nearest .001%. s a l i n i t y . Temperatures were corrected to give the ambient temperature at the depth of each b o t t l e to the nearest .01 C, and oxygen readings were corrected to give disso l v e d 0^ concentrations i n ml/1. Densities, expressed as sigma-t values, were determined from corrected temperature and s a l i n i t y values using U.S. Navy Hydrographic O f f i c e nomographs. T-S diagrams were then drawn f o r each s t a t i o n for the period from May 1971 to February 1972, and shallow, intermediate and deep waters were d i f f e r e n t i a t e d according to natural groupings of T-S points. 16 At Geo-1, f o r example, a l l T-S points f o r water of greater than 200 m could be enclosed w i t h i n a r e l a t i v e l y small region of the T-S diagram. Water from 100-200 m, while forming a smaller p o r t i o n of the water column, f e l l i n t o a l a r g e r , more d i f f u s e T-S envelope. The l a r g e s t area of the diagram consisted of water of l e s s than 100 m. Thus a T-S en-velope for water of 250-390 m depth could be drawn and termed "deep" water, while the water from 100-200 m could be enclosed i n another en-velope and termed "intermediate" water. Using t h i s method a p a i r of T-S envelopes for deep and intermediate water was produced f o r each s t a t i o n with the exception of Boundary Pass, where mixing processes were thorough and d i f f e r e n t water types could not be d i f f e r e n t i a t e d . Con-centrations of the F i f t h Copepodite Stage (C-V) of Calanus plumchrus were then superimposed on p l o t s of the T-S envelopes. This generated a s e r i e s of T-S-P diagrams (Bary, 1963b) for each s t a t i o n ( F ig. 3), ex-cluding Boundary Pass, and f a c i l i t a t e d a n a l y s i s of the c o r r e l a t i o n be-tween the d i s t r i b u t i o n of C. plumchrus and T-S c h a r a c t e r i s t i c s of the water. For the purposes of s i m p l i f i c a t i o n , only the C-V was considered i n t h i s a n a l y s i s . The adults were d i s t r i b u t e d i d e n t i c a l l y to the C-V's and the a n a l y s i s applies equally to them. Younger stages were usually found i n near surface water, and w i l l be mentioned i n greater d e t a i l i n the di s c u s s i o n . 17 Figure 3, a-d: T-S-P diagrams for Fra-1, Fra-2, Geo and Ind-9 (Note scale change i n 6d) d.lnd-9 T - S - P 18 EXPERIMENTAL The experiment was designed to expose C-V Calanus plumchrus to three combinations of two environmental parameters, photo-period and water c h a r a c t e r i s t i c s (Table 5). I t s aim was to i n d i c a t e whether decreasing photo-period or a change of water c h a r a c t e r i s t i c s (or both) was necessary to induce moulting and reproductive behaviour. TABLE 5: Experimental Conditions Container Photo-period Culture Water (350 m Geo-1) #1 None - kept i n dark Recently c o l l e c t e d water #2 As i n the f i e l d at C o l l e c t e d i n October surface and stored #3 As i n the f i e l d at Recently c o l l e c t e d surface water C o l l e c t i o n of Animals and Water Calanus plumchrus (C-V) were c o l l e c t e d i n October, 1971, at the Geo-1 s t a t i o n by means of a v e r t i c a l haul with a i m diameter r i n g net constructed of No. 3 mesh nylon n e t t i n g (ca. 1.0 mm aperture width). The net haul was placed i n a white polyethylene s o r t i n g tray, and specimens of Calanus were transferred by large bore dropping p i p e t t e into 4.5 L thermos f l a s k s (Dewar "Isotherm" Vacuum F l a s k s ) . The f l a s k s contained water from 350 m which had been passed through No. 25 plankton netting (ca. 0.075 mm aperture width) to remove phytoplankton and other 19 zooplankton. Water from 350 m was used i n the experiment as t h i s depth corresponds with high d e n s i t i e s of C_. plumchrus. Water was c o l l e c t e d using a 96 L l u c i t e and f i b e r g l a s s sampler, forced by a pressure of approximately 40 p . s . i . through a membrane f i l t e r with 0 . 4 5 y j m e a n pore s i z e (Sartorius Membranfilter) , and stored i n u n s t e r i l i z e d 5 g a l . polyethylene carboys. Both water and animals were taken to the lab as soon as was f e a s i b l e and placed i n a walk-in environment room ( B e l l - C r a f t , model 2002) maintained at about 8.0 C. Experimental Procedure As soon as was p o s s i b l e , specimens of i C . plumchrus were removed from the thermos f l a s k s ; 250 were placed i n each of three 5 g a l . covered, c y l i n d r i c a l , polyethylene containers holding about 4.5 g a l . of 350 m seawater. Extra specimens were placed i n covered 1 L fingerbowls i n the environment room. Two weeks before being used, the 5 g a l . containers were a c i d -washed, rinsed with d i s t i l l e d water, and f i l l e d with f i l t e r e d 350 m seawater. The two week storage time was considered necessary to "age" the containers and water to minimize i n t e r a c t i o n between the walls of the containers and the seawater used i n the experiment (A. Ramnarine, pers. comm.). The stored water was then replaced with water c o l l e c t e d when the experimental s e r i e s was i n i t i a t e d . The three containers were kept i n the environment room. One (#1) was placed i n a l i g h t - p r o o f box and kept i n the dark except f o r 20 short periods during which the water was changed. The other two (//2 and #3) were placed i n a large box p a r t i t i o n e d i n t o two sections, each of which was provided with a 7.5 watt overhead l i g h t source. Photo-period i n the l i g h t box was c o n t r o l l e d with a Day-Night Clock Switch (Fisher S c i e n t i f i c Co.), and length of photoperiod was a l t e r e d r e g u l a r l y to simulate environmental f l u c t u a t i o n s according to the N a u t i c a l Almanac f o r 1971 (Anon,, 1969). Water was changed once each month for four months, and the stage and condition of the animals were recorded at each change. Fresh seawater was c o l l e c t e d monthly at Geo-1 under the conditions described above. The seawater i n containers #1 and #3 was replaced with r e c e n t l y c o l l e c t e d water, but the water i n container #2 was replaced with 350 m seawater c o l l e c t e d i n October and stored i n carboys i n the environmental room. The animals were not fed during the experiment as feeding i n the C-V drops o f f considerably i n the f a l l (Pandyan, 1971; Gardner, pre-liminary observations) and i t was f e l t that the lack of food would not a f f e c t the behaviour of the organisms. 21 RESULTS General D i s t r i b u t i o n The predominant developmental stage of the copepod Calanus  plumchrus Marukawa i s the Stage V Copepodite (Fig. 1) which, f o r s i x months of the year, i s the only stage found i n the S t r a i t of Georgia. Consequently, the d i s t r i b u t i o n of t h i s stage w i l l be described i n d e t a i l and the d i s t r i b u t i o n of other stages w i l l be compared with that of the C-V. C-V Calanus plumchrus were found at a l l stations surveyed. 3 The highest concentrations, expressed as number of organisms/m averaged over a l l depths sampled, occurred i n deep water. The C-V's reached a maximum at Geo-1, where concentrations of greater than 10 3 organisms/m were common. The d i s t r i b u t i o n of a l l stages at Geo-1 between A p r i l , 1971 and A p r i l , 1972 i s shown i n F i g . 3. For c l a r i t y , naupliar stages have been considered as a group and are pl o t t e d only f o r the spring of 1972, while copepodite stages I-IV are pl o t t e d i n -d i v i d u a l l y and are only shown for the spring of 1971. The C-V's were found almost e x c l u s i v e l y below 100 m; however, the f i r s t C-V's to appear i n the year were found throughout the water column, with maximum concentrations i n near surface water. V e r t i c a l s t r a t i f i c a t i o n was sometimes strongly developed (Fig. 3). In e a r l y summer, however, the organisms moved to deep water. Highest concentration at Geo-1, where maximum depth i s 420 m, was found at 300-375 m i n November and December i n 1970, and from J u l y to December i n 1971. C-V's were found down to 22 Figure 4: Concentration with depth of a l l stages at Geo-1 from A p r i l , 1971 to A p r i l , 1972. No naupliar stages were found i n May, 1972. 23 the deepest sampling depth. At a l l other stations the C-V's were usually r e s t r i c t e d to the deepest depths sampled. The second highest o v e r a l l concentration was found at Fra-1, which i s the second deepest of the f i v e s t a t i o n s . Here, concentrations were generally much l e s s than at Geo-1. A major exception occurred i n May, 1971, when the C-V's f i r s t appeared, and 3 the maximum concentration (42/m ) was found at Fra-1. The same phe-nomenon occurred i n 1972, and w i l l be examined i n greater d e t a i l i n the discussion. Concentrations at both Fra-2 and Ind-9 were r e l a t i v e l y 3 low (ca. 0.75/m ). The average concentration was generally higher at Ind-9, but the maximum concentration, i n May, 1971, was very much greater at Fra-2. Concentration also v a r i e d temporally during the period from January, 1971 to January, 1972 (Table 6). TABLE 6: Concentration of C-V's between January, 1971 and January, 1972. (Averaged over the ent i r e water column). Fra-1 Fra-2 Ind-9 BP Geo-1 Avg. Jan. 0.12 0.06 0.07 0.07 7.29 1.52 Feb. 0.04 0.01 0.21 0.09 0.45 0.16 March - - - - - -A p r i l - - - - - -May 41.98 27.62 1.53 2.11 28.61 20.37 June 7.20 3.67 1.84 1.66 9.30 4.73 Ju l y 0.16 0.45 0.76 0.03 14.96 3.27 Aug. 0.39 0.03 0.76 - 10.04 2.24 Sept. 0.03 0.02 2.31 - 11.45 2.76 Oct. 0.52 0.28 0.87 - 12.81 2.90 Nov.* 2.13 0.42 1.27 - 18.69 4.50 Dec. 4.43 0.32 0.27 - 14.99 4.00 Jan. 0.92 0.02 0.41 0.02 3 . 3 S 0.95 *S t a r t i n g i n t h i s month one extra sampling depth was added to Fra-1 at 225 m. 24 Boundary Pass was the only s t a t i o n where C-V's were not found in a l l months. They were absent from August to December, 1971, and 3 in November, 1970. Concentrations were never greater than 3.0/m , and the highest concentrations were found i n the spring, during the early development of the new generation. The d i s t r i b u t i o n of adult C_. plumchrus i s e s s e n t i a l l y the same as that of the C-V. Adult organisms were present at the f i v e s t a t i o n s only from December to March i n each year, with the maximum concentra-tions occurring i n January and February. The males were l e s s common than the females although the unbalanced sex r a t i o was not as pronounced as i n some copepod species (Marshall and Orr, 1955). Maximum concentra-t i o n of males preceded maximum concentration of females by as much as one month. As with the C-V, maximum concentrations of adults were found at Geo-1 and next highest at Fra-1, with low concentrations at the other three s t a t i o n s . Boundary Pass supported a small population of adults despite a n e g l i g i b l e number of C-V's i n the months preceding moulting. A l l other stages were d i s t r i b u t e d i n a s i m i l a r manner, the only v a r i a -t i o n being i n t h e i r p o s i t i o n i n the water column (Fig. 3). L i f e Cycle Trends shown by the l i f e h i s t o r y stages were e s s e n t i a l l y the same at a l l s t a t i o n s with the exception of BP. Moulting to the adult occurred p r i m a r i l y i n January and February, with males developing f i r s t . 25 A l l of the C-V's disappeared by March. Immediately a f t e r moulting, the females were opaque with l i t t l e evidence of developing oviducts. This condition presumably pe r s i s t e d u n t i l f e r t i l i z a t i o n since the only females observed with spermatophores resembled r e c e n t l y moulted s p e c i -mens. The time of f e r t i l i z a t i o n was d i f f i c u l t to determine. Few females were found bearing spermatophores, and maximum concentration of males occurred i n January, p r i o r to the appearance of the maximum concentration of r i p e females. As development of the oviducts pro-ceeded, the transparency of the body increased, and i n those females with oviducts f u l l of eggs the re s t of the body was almost completely transparent. Females i n the completely transparent state often c a r r i e d varying numbers of eggs, ranging from a maximum, i n which the oviducts almost completely f i l l e d the body c a v i t y , to a minimum of a few scattered eggs i n the oviduct. Completely spent females soon died. The males were opaque at a l l stages of the breeding c y c l e . Eggs and naupliar stages were only studied i n the spring of 1972. A few eggs were i n the water as early as January, but the maximum concentration of eggs was found i n February. Development through the naupliar stages occurred during February and March, with the Stage I I I Nauplius (N-III) predominating. The four copepodite stages preceding the C-V were passed through f a i r l y quickly with no stage present i n high concentrations for more than two consecutive months (Table 7, F i g . 5). Very few copepodites were found i n March, 1971, 26 Figure 5. Concentrations of the copepodite stages between November, 1970 and August, 1971 (average of a l l s t a t i o n s ) . 27 TABLE 7: Development through the f i r s t four copepodite stages i n 1971. (Concentrations i n no./m^). Fra-1 Fra-2 Ind-9 BP Geo-1 Avg. C-I A p r i l 1.69 .0.06 0.21 0.07 2.55 0.92 C-II A p r i l 11.17 0.90 2.46 1.60 24.89 8.20 May 0.97 1.56 0.12 2.96 0.13 1.13 C-III A p r i l 4.53 0.13 0.11 0.26 7.16 2.44 May 2.43 0.61 0.17 5.35 0.39 1.79 June 0.10 0.05 - 0.01 0.01 0.03 C-IV A p r i l 0.21 0.03 _ 0.03 0.17 0.09 May 11.51 12.96 1.10 6.80 1.42 6.76 June 0.37 0.40 0.05 0.25 0.02 1.57 but by A p r i l large concentrations of C-I's, I l ' s and I l l ' s had developed, with C-II's predominating. By May, C - I l ' s , I l l ' s , IV's and V's were present with IV's and V's predominating. In June, C-V's predominated and by July only C-V's were found. Hydrographic Data and T-S-P Results Ind-9, Geo-1, BP and the two Fraser Plume stati o n s exhibited varying hydrographic conditions and were considered representative of the hydrographic conditions present i n the S t r a i t of Georgia and sur-rounding waters. The general c h a r a c t e r i s t i c s of the st a t i o n s have been presented e a r l i e r , and the hydrography of the S t r a i t of Georgia and i t s surrounding waters has been discussed by numerous authors (Waldichuk, 1957; Legare 7, 1957; Pickard, 1956; T u l l y and Dodimead, 1957; Gilmartin, 1964) . A major hydrographic occurrence during the time of the study was an i n t r u s i o n of water of oceanic o r i g i n which slowly replaced bottom 28 water at Geo-1 between August and November, 1971 ( F i g . 6). Another large scale i n t r u s i o n occurred at Ind-9 i n December and January, 1970-71, and again i n 1972. Late winter i n t r u s i o n s were also observed at Fra-1 and Fra-2, but on a smaller scale. Raw data has been tabulated i n IOUBC Data Reports (1971, 1972 ( i n press), 1973 ( i n preparation)).At each of the four sta t i o n s for which T-S-P r e l a t i o n s were analyzed, the majority of occurrences of C^ . plumchrus f e l l w i t h i n the boundaries of the two envelopes. Most of the exceptions to t h i s tendency occurred immediately following the breeding season, when new C-V's appeared and were found throughout the water column, often being concentrated near the surface. Other exceptions were noted but represented l e s s than 5% of the t o t a l number of occurrences p l o t t e d . This c o r r e l a t i o n between occurrences of the C-V and c e r t a i n T-S c h a r a c t e r i s t i c s was best demonstrated at Geo-1 (Fig. 3c). If the early developmental stages of the new generation were excluded, a l l of the points p l o t t e d l a y w i t h i n the two T-S envelopes, and 97% were with-i n what was termed "deep" water. Boundary Pass i s the only exception to the above a n a l y s i s . Inversions of temperature and s a l i n i t y were frequently observed, and l e s s frequent density inversions were also noted. Often, the water column was almost isothermal, and oc c a s i o n a l l y the v e r t i c a l s a l i n i t y gradient was very small. The high degree of mixing, and the disappear-ance of C_. plumchrus from t h i s area over extended periods 5 suggested that mixing processes and t h e i r d i r e c t e f f e c t s (e.g. on the a v a i l a b i l i t y 29 Figure 6: Salinity isolines at Geo-1 during 1971. /Cru ise Date Geo-1 Salinity (%o) 30 of food) were the prime factors which regulated the d i s t r i b u t i o n of the copepod i n t h i s area, and that chemical parameters of the water were not important i n excluding C_. plumchrus at c e r t a i n times of the year. Experimental Results Results under a l l three experimental conditions were v i r t u a l l y i d e n t i c a l ( F i g . 7). No change occurred during the f i r s t 19 days, at which time moulting began to occur. Peak numbers of females occurred at day 95, followed by a rapid d e c l i n e as the females shed t h e i r eggs and died. T o t a l population s i z e declined almost l i n e a r l y between day 19 and the termination of the experiment. Extra C-V's l e f t i n f i n g e r -bowls for the duration of the experiment showed s i m i l a r trends, a l -though m o r t a l i t y may have been s l i g h t l y higher. The only noticeable d i f f e r e n c e observed i n the three containers was the s l i g h t l y lower m o r t a l i t y i n container #1 (56.8%) compared with containers #2 (64.4%) and #3 (66.8%). Times of moulting and development i n the experiment and i n the f i e l d were compared. By February 19, a l l of the laboratory population had moulted and the majority of the females were spent. In the f i e l d i n February, the number of C-V's had greatly declined but s t i l l represented approximately 7% of the t o t a l population. Also, the majority of the females were ovigerous and transparent. In the labora-tory i n December approximately 35% of the population were adults. The f i e l d population was only 10% adult at t h i s time. 31 Figure 7: Experimental r e s u l t s . T o t a l number of animals, numbers of C-V's, C-VI males and C-VI females are p l o t t e d for each experimental condition over the period of the experiment. e o e o o o o CM "O1 to oo o CM 32 DISCUSSION Campbell (1934) suggests that Calanus plumchrus (which she re f e r r e d to as Calanus tonsus Brady) i s found i n abundance everywhere i n the S t r a i t of Georgia, with maximum numbers between 100 m and 200 m. The present study in d i c a t e s that i t s d i s t r i b u t i o n i s perhaps not as widespread and that maximum numbers may occur w e l l below 200 m. The r e s t r i c t i o n s on i t s d i s t r i b u t i o n appear to be p r i m a r i l y the r e s u l t of an a f f i n i t y f o r deep water. T-S-P an a l y s i s indicates a strong a s s o c i a t i o n between the predominant developmental stage, the C-V, and deep and intermediate water at four of the stati o n s studied. The reasons for t h i s a s s o c i a t i o n are not known but I t s a f f e c t s are obvious. The deepest stations support high concentrations of the copepod whereas shallower stations support only low concentrations. Newly appearing C-V's, however, are more c l o s e l y associated with near surface water, and do not migrate i n t o deep water f o r f i v e to s i x weeks. The f l u c t u a t i o n s i n T-S-P r e l a t i o n s with growth stage are believed at l e a s t p a r t i a l l y r e l a t e d to food requirements. C_. plumchrus i s an herbivore and i t s e a r l y development corresponds with the development of the spring phytoplankton bloom. The factors involved i n regul a t i n g t h i s timing are not c l e a r . In the experimental s e r i e s neither the culture i n complete darkness nor the cult u r e i n water c o l -l e c t e d i n October and stored produced noticeable d e v i a t i o n i n r e s u l t s from the culture maintained i n conditions approximating those i n the 33 f i e l d . This suggests that neither l i g h t conditions nor unique water properties are the cues which e l i c i t moulting and breeding behaviour. The C-V's which were kept i n fingerbowls also moulted despite being kept i n the same containers and water throughout the experiment. This suggests that the p h y s i c a l disturbance associated with changing the water did not a r t i f i c i a l l y induce moulting. Furthermore, the s t a b i l i -z a t ion of the laboratory population for almost three weeks p r i o r to the f i r s t i n d i c a t i o n of moulting suggests that the laboratory environ-ment, per se, did not i n i t i a t e the moult. I t i s p o s s i b l e , however, that handling of the copepods i n the laboratory was responsible for a c c e l e r a t i n g the moulting process. For a l l three experimental condi-t i o n s , as w e l l as for the fingerbowls, moulting i n the laboratory com-menced, and was completed, e a r l i e r than moulting i n the f i e l d . Since t h i s phenomenon was observed under a l l three conditions, neither of the experimental conditions of photoperiod nor of water type would seem to have favoured i t . One d i f f e r e n c e between the laboratory s i t u a t i o n and the f i e l d s i t u a t i o n was temperature. Temperatures i n the environ-mental chamber (ca. 8.0 C) were lower than corresponding f i e l d temper-atures (Ca. 8.8 C). T h e o r e t i c a l l y , lower temperature would favour a slower rate of development, not a f a s t e r r a t e ; however, average f i e l d temperatures between December and January, when moulting was f i r s t observed i n the f i e l d , decreased. Consequently, a lower temperature might be s l i g h t l y more favourable f o r moulting. 34 At Fra-1, Fra-2, BP and Geo-1 average f i e l d temperatures f o r depths at which C. plumchrus were found also dropped between November and December, 1971, yet no moulting occurred at t h i s time. The cor-responding temperature drop was not observed at Indian Arm u n t i l l a t e December, yet moulting at a l l four stations was f i r s t noticed at the same time. Consequently, temperature would not seem to be the f a c t o r which i n i t i a t e s development from the C-V to the adult, despite i t s possible r o l e i n the rate at which t h i s development proceeds once started. Similar arguments may be applied to s a l i n i t y . Fluctuations of s a l i n i t y between d i f f e r e n t s t a t i o n s are of greater magnitude than temporal changes at the same s t a t i o n , and v a r i a t i o n s i n the extent and timing of s a l i n i t y f l u c t u a t i o n s at each s t a t i o n do not produce con-comitant v a r i a t i o n s i n the animal's behaviour. The i n t r u s i o n of oceanic water i n t o the S t r a i t of Georgia i s noted at BP and Geo-1 i n the f a l l . Intrusions at the other s t a t i o n s , however, occur some months l a t e r and thus the simultaneous.replacement of deep water which would be necessary to induce moulting at a l l stat i o n s at the same time does not occur. No sin g l e f a c t o r examined would seem to be operating as the sole cue and a s p e c i f i c combination of factors may be required. The s i t u a t i o n i s to a large extent analogous to that described by Watson and Smallman (1971a, b) f o r the freshwater cyclopoid Diaeyelops navus.  Diacyclops responds to c e r t a i n forms of environmental s t r e s s by 35 entering a form of arrested development, or diapause. I n i t i a t i o n and termination of the diapause are governed by a combination of photoperiod and temperature. - Diapause i s a condition characterized by an abrupt onset of dormancy, followed by resumption of growth and terminating i n metamor-phosis, rapid growth or reproductive a c t i v i t y (Hoar, 1966). This des-c r i p t i o n c l o s e l y f i t s the behavioural pattern of C_. plumchrus. Once the copepod has been i n the C-V stage for about two months and has migrated to deep water, feeding rate drops o f f and a c t i v i t y decreases. A f t e r overwintering i n t h i s state, the diapause i s terminated and moult-ing to the adult occurs. As shown previously, the cues involved i n t h i s behaviour are not c l e a r . I t might be postulated that as the spring phytoplankton bloom subsides e i t h e r the lack of food or the n u t r i t i o n a l state of the animal (e.g. f u l l o i l sac) t r i g g e r s a s e r i e s of p h y s i o l o g i -c a l events which a r r e s t s somatic development. I t i s at t h i s time that the population migrates deeper i n the water column. At greater depths, where water movements are l e s s , the energy expended i n maintaining p o s i t i o n would be l e s s . Conservation of energy i n t h i s manner may be important since the process of egg production exhausts a l l of the body's o i l reserves, leaving a female that i s completely transparent except f o r her eggs. The lower metabolism may also aid i n the timing of the onset and completion of diapause. Furthermore, McLaren (1963) suggests that an energy bonus i s obtained by animals which go through a d i e l v e r t i c a l 36 migration. He hypothesizes that animals feeding i n near surface waters at night, and then moving to deeper, cooler waters to a s s i m i l a t e t h e i r food and to r e s t , obtain more energy than animals which c o n t i n u a l l y feed at the surface. In addition, McLaren considers seasonal migration to be e s s e n t i a l l y a v a r i a t i o n of d i e l migration and suggests that season-a l migrants also obtain an energy bonus. plumchrus, therefore, might be u t i l i z i n g a v a i l a b l e energy more e f f i c i e n t l y by i t s migratory behaviour. As the spring bloom approaches, e i t h e r the animal becomes r e -ceptive to c e r t a i n environmental cues or a preset "clock" t r i g g e r s another s e r i e s of p h y s i o l o g i c a l events which terminates the arrested development and simultaneously i n i t i a t e s moulting. Further i n v e s t i g a t i o n of t h i s phenomenon i s required to uncover the f a c t o r s which are operating as cues. whatever cues are being used, they allow for f a i r l y p recise timing. The timing of the onset of the phytoplankton bloom i s v a r i a b l e , however, and some safeguard must be present to prevent the copepod from developing at a time of i n s u f f i c i e n t food. The length of time spent i n the N-III suggests a means by which t h i s might be accomplished. Develop-ment from the egg to the N-III must proceed quickly and i n deep water, since few N-I and N-II stages were found i n the f i e l d and those that were occurred only at the deepest depths sampled. The N-III, however, was predominant i n the f i e l d f o r about s i x to seven weeks and was pre-sent i n the period immediately preceding the spring bloom. The N-III 37 i s the f i r s t naupliar stage that feeds (Pandyan, 1971). A short pause i n development at t h i s stage serves two purposes. I t allows the organ-ism time to migrate from the deep water i n which the eggs were l a i d to near surface water where the phytoplankton bloom develops. Furthermore, i f the rate of development of the N-III i s influenced by the amount of a v a i l a b l e food, development would not proceed u n t i l the bloom commenced. Preliminary laboratory i n v e s t i g a t i o n s associated with t h i s study suggest that the N-III i s capable of moulting i n much l e s s time than i s taken i n the f i e l d , supporting the hypothesis of i t s r o l e i n adjusting the timing of the copepod's early development. Once the phytoplankton bloom has begun, development through the remaining naupliar stages and the f i r s t four copepodite stages proceeds q u i c k l y , with the f i r s t C-V's appearing i n May, from f i v e to seven weeks a f t e r the N-III begins to disappear. This period i s characterized by intense grazing and the development of a l a r g e , f u l l o i l sac. Food r e -serves stored at t h i s time must be s u f f i c i e n t to carry the organism through i t s over-wintering phase and also through the breeding season, since feeding i s minimal i n the l a t e C-V's and adults (Pandyan, 1971). This c a r e f u l l y timed and opportunistic l i f e c ycle i s e s s e n t i a l l y the same at Geo-1, Fra-1, Fra-2 and Ind-9. The major de v i a t i o n from the expected occurred i n May, 1971, when Fra-1 had a much l a r g e r concentration of C_. plumchrus than Geo-1, and when Fra-2 supported almost as high a concentration as Geo-1. During t h i s time the Fraser Plume region i s 38 apparently better suited for the development of the C-V. This could be caused by many f a c t o r s , as the Fraser River runoff creates a unique set of conditions. S i l t i n the runoff produces a nearly opaque surface layer i n the v i c n i t y of the r i v e r mouth, g r e a t l y increasing l i g h t a tten-uation and consequently reducing primary p r o d u c t i v i t y to a minimum (Parsons, Stephens and LeBrasseur, 1969). Further from the r i v e r mouth, l i g h t attenuation i s not as intense but the freshwater runoff creates a stable water column with a r e l a t i v e l y shallow mixed layer depth (Parsons et a l . , 1969). These conditions are i d e a l for the production of phytoplankton, and thus p r o d u c t i v i t y under the Plume i s higher than at s t a t i o n s such as Geo-1 which are not as strongly influenced by the Plume. The s t r a t i f i c a t i o n of the water r e s u l t s i n a more intense v e r t i -c a l s t r a t i f i c a t i o n of zooplankton and phytoplankton under the Plume. The runoff also contributes nutrients to the water column i n the form of substances dissolved i n the water and absorbed on p a r t i c l e s i n the s i l t . Moreover, even i n periods of low runoff (November-January), benthic diatoms were present i n near surface water at Fra-1 (Gardner, p r e l i m i -nary i n v e s t i g a t i o n s ) . Presumably t h i s r e s u l t s from entrainment of bottom water near the mouth of the r i v e r . Consequently, i n periods of intense runoff, the concentration of benthic diatoms may reach r e l a t i v e l y high values. Pandyan (1971) i n d i c a t e s that C-V Calanus plumchrus feed r e a d i l y , and even p r e f e r e n t i a l l y , on Coscinodiscus concinnus. Since many of the benthic diatoms observed at Fra-1 p r i o r to peak runoff were 39 large c e n t r i c types s i m i l a r to C_. concinnus, i t i s p o s s i b l e that they c o n s t i t u t e a n a d d i t i o n a l food source for the developing copepods and may be important i n increasing the capacity of the region to support a large population of C_. plumchrus, p a r t i c u l a r l y before the bloom reaches i t s peak. Lack of predation i s another f a c t o r which contributes to the r i s e of a very large population of C_. plumchrus. Lebrasseur et a l . , (1969) i n d i c a t e that l a r v a l Pink and Chum salmon feed p r e f e r e n t i a l l y on smaller copepod species rather than on young developmental stages of C_. plumchrus. This s i t u a t i o n i s reversed when j u v e n i l e salmon appear. The j u v e n i l e s can feed more e f f i c i e n t l y on larger copepods, and consequently, a switch i n food source occurs with the salmon's development. Unfortunately, LeBrasseur et a l . (1969) did not sample past May, 1969, and d i d not record the f u l l extent of salmon predation on the C_. plumchrus stocks. Birman (1958), i n h i s observations on the extent of predation of Oncorhynchus sp. on Calanus c r i s t a t u s i n the Kamchatka area, estimates that the salmon were the cause of a 90% drop i n the biomass of the copepod over the period of the spawning run. Therefore, i t seems l i k e l y that the m o r t a l i t y of about 85% of the C. plumchrus stock, observed i n t h i s study between May and June, 1971, was caused by continued predation. However, observations on new C-V's i n the laboratory suggest that there i s a higher rate of m o r t a l i t y i n the f i r s t few weeks of t h e i r development than i s observed i n l a t e r 40 weeks when feeding and a c t i v i t y have both decreased. Hence, i t i s also possible that i n the process of metabolic slowdown and migration to deep water there i s some degree of natural mortality which c o n t r i -butes to the drop i n population observed at t h i s time. Temporal f l u c t u a t i o n s i n the concentration of C_. plumchrus at Geo-1 are also anomalous. The increase i n concentration between August and November (Table 5) cannot be a t t r i b u t e d to reproduction since spring breeding i s f i n i s h e d and no new adults have appeared. The massive f a l l i n t r u s i o n i s believed to be the mechanism responsible for the increase i n numbers. The i n t r u d i n g waters are bottom waters p a r t i a l l y of oceanic o r i g i n and characterized by higher s a l i n i t y and s l i g h t l y higher temperature than the water they replace. This i s pre-c i s e l y the type of water with which C-V Calanus plumchrus would be associated. Evidently the i n t r u d i n g water c a r r i e s a moderate concen-t r a t i o n of the copepod to Geo-1. The water intrudes i n the form of a wedge ( F i g . 5), beginning i n August and reaching a peak i n November, when the bottom 250 m of the water column have been p a r t i a l l y or completely replaced. I t i s not necessary f o r the intruding water to contain an excessively high concentration of C_. plumchrus, as the further movement of the animal into intruding bottom water would act as a concentrating mechanism. Since the minimum depth of the population of C. plumchrus at Geo-1 does not decrease s i g n i f i c a n t l y when the s a l t wedge intrudes, a phenomenon of t h i s type may be occurring. 41 Calanus plumchrus i n the i n t r u d i n g water apparently are not associated with i t when i t passes the Boundary Pass s t a t i o n . The i n -coming water i s shown c l e a r l y i n the hydrographic data from the s t a t i o n ; however, there i s no simultaneous increase i n the concentration of C^ . plumchrus. On the contrary, the organism i s absent from the s t a -t i o n at t h i s time. Furthermore, s u p e r f i c i a l examination of b i o l o g i c a l samples from Haro S t r a i t and the S t r a i t of Juan de Fuca produced no evidence of large concentrations of C, plumchrus associated with the incoming oceanic water. The C^ . plumchrus are evidently from the area southeast of the Geo-1 s t a t i o n . Much of t h i s region i s over 350 m deep and intruding bottom water could pick up Calanus from the displaced water i n a manner s i m i l a r to the concentrating mechanism described above. I t would perhaps be p r o f i t a b l e to monitor the concentration of the organism on a l i n e of s t a t i o n s between BP and Geo-1 and determine the source of the C_. plumchrus. Problems a r i s e i n explaining the means by which C_. plumchrus i s stimulated to move into i n t r u d i n g water. P r i o r to the i n t r u s i o n , the population does not extend to the bottom of the water column at Geo-1. Some factors must i n i t i a t e the descent. These are not s p e c i -f i e d i n the present study, although i t i s evident that the temperature and s a l i n i t y tolerance of the copepod does not prevent i t from enter-ing the intruding water. Temperature and s a l i n i t y c h a r a c t e r i s t i c s of the intruding water are very s i m i l a r to those of the water being 42 displaced. The increase i n average s a l i n i t y i s about 0.35%, and i n average temperature i s about 0.5 C for a l l water deeper than 200 m at Geo-1 between J u l y and November, 1971. In some months, s i m i l a r v a r i a t i o n s i n T and S can be found at the s t a t i o n over the depth range i n which C_. plumchrus i s found. S t r a i t of Georgia bottom water i s formed from a mixture of an annual i n t r u s i o n of oceanic water and of runoff from the Fraser River with which i t mixes i n the southern entrance passages to the S t r a i t of Georgia. The intruding water and the water being displaced are therefore of s i m i l a r o r i g i n but formed one year apart. Any d i f -ferences i n the two water types r e s u l t i n g from the temporal v a r i a t i o n i n t h e i r formation are apparently not s u f f i c i e n t to create a b a r r i e r to the migration of C_. plumchrus. As the oceanic water intrudes, the o r i g i n a l bottom water i s displaced. Mixing processes between the i n -truding water and the o r i g i n a l water w i l l be responsible f o r some of the movement of the copepod into the new bottom water. Water displaced upwards by the i n t r u s i o n has temperature and s a l i n i t y c h a r a c t e r i s t i c s which s t i l l f a l l w ithin those with which the copepod i s associated. However, there i s no concomitant r i s e i n the minimum depth of the po-p u l a t i o n . Possibly negative phototactism i s involved i n keeping the population at depth, but no data were found to support t h i s hypothesis. Water movements are also extremely important i n the d i s t r i b u -t i o n of C_. plumchrus at Boundary Pass. This i s the one s t a t i o n at 43 which the organism i s not found at a l l times of the year and i t appears that the s t a t i o n supports only a transient population. The d i s t i n c t d i v i s i o n between shallow, intermediate and deep water that occurs at the other s t a t i o n s i s not found here and thermal s t r a t i f i -c a t i o n r a r e l y occurs. Fluctuations i n hydrographic properties over a t i d a l cycle are of a magnitude s i m i l a r to or greater than f l u c t u a -tions observed i n a se r i e s of monthly observations over an extended time period (Anon.,1972). Consequently, a d e s c r i p t i o n of hydrographic c h a r a c t e r i s t i c s based on time s e r i e s data that has not been adjusted f o r t i d a l influence s u f f e r s from a lack of p r e c i s i o n . I t can, however, be stated that the main c h a r a c t e r i s t i c of the region i s that the water i s w e l l mixed. BP i s on the f r i n g e of the Fraser River Plume when the r i v e r i s f l o o d i n g . Often the s t a t i o n i s with i n the Plume at low t i d e and out of the Plume at high t i d e . The pattern of d i s t r i b u t i o n at t h i s s t a t i o n i s thus subject to t i d a l i n f l u e n c e . This influence i s probably one of the main factors a f f e c t i n g the d i s t r i b u t i o n of C_. plumchrus at the s t a t i o n . Immediately a f t e r spawning, when the f i r s t N - IIl's appear i n the water, they are found i n r e l a t i v e l y large numbers at BP, despite the f a c t that no C-V's were found there i n the months preceding moulting and that very few adults were found. The same i s true of young copepodite stages. In 1971, as the new generation developed, for each stage at l e a s t one s t a t i o n had a peak concentration l e s s than that found 44 at BP (Table 6). The dec l i n e i n concentration between May and June, however, was most serious at BP, and by August none of the new C-V's remained. This f l u c t u a t i o n i n numbers i s best described by a combination of hydrographic and b i o l o g i c a l phenomena. The lack of eggs, N-I's and N-II's from deep samples at BP suggests that there i s some input of N-III's from outside the system. During the spring runoff, i t has been shown that primary and secondary production, and hence concentra-t i o n of C_. plumchrus, i s higher under the Fraser River Plume. I t i s at t h i s time that BP i s most strongly influenced by the Plume and the murky Plume waters are often observed at the s t a t i o n e i t h e r as small transient patches or as a front that i s continuous to the r i v e r mouth. When patches of Plume waters extend to the Boundary Pass s t a t i o n , i t i s probable that large numbers of naupliar and copepodite stages are brought with them. At th i s time of year, mixing i s maximal and the immigrant naupliar and copepodite stages become mixed to some depth i n the water column. The extreme depth of the mixed layer suggests that phytoplankton production at BP i s very low, and i t i s probable that most of the Calanus entering t h i s region do not survive and are c a r r i e d away by cur-rents. The observed concentration of young copepodites i s probably maintained by immigration from the Plume. Once development has proceeded to the C-V and the organisms have migrated to deep water, no further input of Calanus occurs. Some C-V's which had obtained most of t h e i r food while 45 i n the Plume and were then transported to BP are l e f t there to form a temporary population. Water movement i n t h i s area i s such that there i s a net transport of bottom water into the S t r a i t of Georgia (Waldichuk, 1957). This bottom water i s replaced by a mixture of surface water, which contains no C_. plumchrus, and water from the d i r e c t i o n of Haro S t r a i t , where few i f any C_. plumchrus are found. The net e f f e c t of t h i s type of c i r c u l a t i o n pattern would be to decrease the number of C_. plumchrus at Boundary Pass, which i s apparently what happens. The o v e r a l l d i s t r i b u t i o n of Calanus plumchrus, then, i s a r e s u l t of i n t e r a c t i o n between the organism, "T-S" c h a r a c t e r i s t i c s of the environment and mixing processes. The nature of i t s l i f e c ycle i s such that a r a d i c a l change i n i t s v e r t i c a l d i s t r i b u t i o n occurs annually. The young stages develop i n near surface waters, where food i s p l e n t i f u l , but the C-V i s c l o s e l y associated with bottom waters, p o s s i b l y to ensure the e f f i c i e n t use of energy stored during i t s development. Hence, the organism abounds only i n areas where the combination of deep water and high surface p r o d u c t i v i t y i s found. Light may also be involved i n r e g u l a t i n g the behaviour and d i s t r i b u t i o n of the organism, but the extent of t h i s involvement i s s t i l l not c l e a r . Where the proper conditions e x i s t , the copepod i s i n v a r i a b l y present i n high numbers. Moreover, when the new generation forms i n the spring, Calanus plumchrus i s the dominant zooplankton species i n the S t r a i t of Georgia. The s i z e of the population at t h i s time makes the C^ . plumchrus stock a major food source for young salmon and other 46 f i s h which graze on zooplankton. Consequently, i t holds a major p o s i t i o n i n the trophic r e l a t i o n s h i p s w i t h i n the S t r a i t . 47 REFERENCES Anon, 1969. The N a u t i c a l Almanac for the year 1971. N a u t i c a l Almanac O f f i c e , United States Naval Observatory, Wash., D.C. , 1971. Data Report No. 32. I n s t i t u t e of Oceanography, Univer-s i t y of B r i t i s h Columbia. , 1972. (In press). Data Report No. 33. I n s t i t u t e of Oceanography U n i v e r s i t y of B r i t i s h Columbia. Aron, William. 1962. D i s t r i b u t i o n of Animals i n the Eastern North P a c i f i c . J . F i s h . Res. Bd. Can. 19 (2): 271-314. Barber, R.T. and J.H. Ryther. 1969. Organic chelators: Factors a f -f e c t i n g primary production i n the Cromwell Current up-welling. J . exp. mar. B i o l . E c o l . 3: 191-199. Bary, B. McK. 1963a. Temperature, S a l i n i t y and Plankton i n the East-ern North A t l a n t i c and Coastal Waters of B r i t a i n , 1957. I. The Ch a r a c t e r i z a t i o n and D i s t r i b u t i o n of Surface Waters. J . F i s h . Res. Bd. Can. 20 (3): 789-826. , 1963b. Temperature, S a l i n i t y and Plankton i n the Eastern North A t l a n t i c and Coastal Waters of B r i t a i n , 1957. I I . The Relationships Between Species and Water Bodies. J . F i s h . Res. Bd. Can. 20 (4): 1031-1065. 1963c. Temperature, S a l i n i t y and Plankton i n the Eastern North A t l a n t i c and Coastal Waters of B r i t a i n , 1957. I I I . The D i s t r i b u t i o n of Zooplankton i n Relation to Water Bodies. J . F i s h . Res. Bd. Can. 20 (6): 1519-1548. 48 Bary, B. McK. 1964. Temperature, S a l i n i t y and Plankton i n the Eastern North A t l a n t i c and Coastal Waters of B r i t a i n , 1957. IV. The Species' Relationship to the Water Body; I t s Role i n D i s t r i b u t i o n and i n S e l e c t i n g and Using Indicator Species. J . F i s h . Res. Bd. Can. 21 (1): 183-201. B i e r i , Robert. 1959. The D i s t r i b u t i o n of the Planktonic Chaetognatha i n the P a c i f i c and t h e i r Relationship to the Water Masses. Limn, and Oce. 41 (1): 1-28. Birman, I.B. 1958. New Information on the marine period of l i f e and the marine f i s h e r y of P a c i f i c Salmon. Ikhtiologicheskaia Komissiia Akad. Nauk. SSSR, Trudy Soveshchanii, No. 10: 154-164, Moscow. F i s h . Res. Bd. T r a n s l a t i o n No. 357. Brady, G.S. 1883. Report on the Copepoda. Rep. S c i . Res. H.M.S. Challenger, Zool. 8 (23): 1-142. Brodsky, K.A. 1938. Contribution to the ecology and morphology of C_. tonsus Brady (syn. : C_. plumchrus Marukawa) of far-eastern seas. Compt. Rend. Acad. S c i . U.S.S.R. 19 (1):. 123-126. Campbell, M.H. 1929a. A Preliminary Quantitative Study of the Zoo-plankton i n the S t r a i t of Georgia. Trans. Roy. Soc. Can. Ser. 3, 23 (5): 1-28. , 1929b. Some free-swimming copepods of the Vancouver Island region. I. Trans. Roy. Soc. Can. 23: 303-332. , 1930. Some free-swimming copepods of the Vancouver Island region. I I . Trans. Roy. Soc. Can. Sect. 5, B i o l . S c i . 24 (1): 177-182. 49 Campbell, M.H. 1933. Calanus tonsus Brady (= £. plumchrus Marukawa) as an Economic Factor in the Strait of Georgia. Proc. Fifth Pan-Pacific Sci. Cong. Can. 3: 2003-2008. , 1934. The Life History and Post Embryonic Development of the Copepods, Calanus tonsus Brady and Euchaeta japonica Marukawa. J. Biol. Bd. Can. 1 (1): 1-65. Carritt, D.E. and J.H. Carpenter. 1966. Comparison and Evaluation of Currently employed Modifications of the Winkler Method for Determining Dissolved Oxygen in Seawater; A NASCO Report. J . Mar. Res. 24: 286-318. Fager, E.W. and J.A. McGowan, 1963. Zooplankton species groups in the North Pacific. Sci. 140: 453-460. Foerster, R.E. 1968. The Sockeye Salmon, Oncorhynuhus nerka. Fish Res. Bd. Can., Ottawa. Gilmartin, Malvern. 1964. The Primary Production of a British Columbia Fjord. J. Fish. Res. Bd. Can..21 (3): 505-537. Hebard, J.F. 1966. Distribution of Euphausiacea and Copepoda off Oregon in Relation to Oceanographic Conditions. Ph.D. Thesis, Oregon State University. Heinrich, A.K. 1961. Seasonal phenomena in plankton of the world ocean. I. Seasonal phenomena in the plankton of high and temperate l a t i -tudes. (Transl. from) Trans. Inst. Okeanol. Akad. nauk S.S.S.R. 51: 57-81. Avail, from Clearinghouse Fed. Sci. Tech. Inform., Springhill, Va. 1163-19929. 50 Heinrich, A.K. 1962a. On the production of copepods i n the Bering Sea. Int. Rev. ges. Hydrobiol. 47 (3): 465-469. . 1962b. The l i f e h i s t o r i e s of plankton animals and seasonal cycles of plankton communities i n the oceans. J . Cons. Int. Exp. Mer. 27: 15-24. . 1963. Seasonal Phenomena i n the Plankton of the Northeast P a c i f i c Ocean. Oceanology 8:231-239. Helland-Hansen, B. 1916. Nogen Hydrografiske Metoder. Skand. Naturforsker note, K r i s t i a n i a (Oslo), 'it'-. Hoar, W.S. 1966. General and Comparative Physiology. P r e n t i c e - H a l l Inc., Englewood C l i f f s , N.J. Jaschnov, V.A. 1961. Water masses and plankton. I. Species of Calanus finmarchicus s . l . as i n d i c a t o r s of d e f i n i t e water masses. (In Russian). Zool. Zhur. 40 (9): 1314-1324. , 1963. Water masses and plankton. 2. Calanus g l a c i a l u s and C_. p a c i f i c u s as i n d i c a t o r s of d e f i n i t e water masses i n the P a c i f i c . (In Russian). Zool. Zhur. 42 (7): 1005-1021. . 1970. D i s t r i b u t i o n of Calanus spp. i n the seas of the North-ern Hemisphere. Int. Rev. ges. Hydrobiol. Hydrogra. 55: 197-312. J i l l e t , J.B. 1968. Calanus tonsus (COPEPODA, CALANOIDA) i n Southern New Zealand Waters with Notes on the Male. Aus. J . mar. Fresh-wat. Res. 19: 19-30. 51 Johnson, M.W. 1956. The Plankton of the Beaufort and Chukchi Sea areas of the A r c t i c and i t s r e l a t i o n to the Hydrography. Arct. Inst, of N. Amer., Tech. Paper No. 1. Johnson, R. 1964. Sea water, the n a t u r a l medium of phytoplankton. I I . Trace metals and c h e l a t i o n , and general di s c u s s i o n . J . Mar. B i o l . Ass. U.K. 44: 87-109. LeBrasseur, R.J. 1964. Marine Ecology of the P a c i f i c Salmon. Ms. F i s h . Res. Bd. Can., Nanaimo, B.C. LeBrasseur, R.J., W.E. Barraclough, O.D. Kennedy and T.R. Parsons. 1969. Production Studies i n the S t r a i t of Georgia. Part III. Observations on the Food of La r v a l and Juvenile F i s h i n the Fraser River Plume, February to May, 1967. J . exp. mar. B i o l . E c o l . 3: 51-61. Le'gare^, J.E.H. 1957. The q u a l i t a t i v e and q u a n t i t a t i v e d i s t r i b u t i o n of plankton i n the S t r a i t of Georgia i n r e l a t i o n to c e r t a i n oeeanographic f a c t o r s . J . F i s h . Res. Bd. Can. 14 (3): 521-552. Lewis, A.G. and A. Ramnarine. 1969. Some Chemical Factors A f f e c t i n g the E a r l y Developmental Stages of Euchaeta japonica (Crustacea: Copepoda:Calanoida) i n the Laboratory. J . F i s h . Res. Bd. Can. 26: 1347-1362. Lewis, A.G., A. Ramnarine and M.S. Evans. 1971. Natural chelators-an i n d i c a t i o n of a c t i v i t y with the calanoid copepod Euchaeta japonica. Mar, B i o l . 11 (1): 1-4. 52 MacGinitie, G.E. 1955. Invertebrate Marine Fauna from Pt. Barrow, Al a . Publ. #4221, Smithsonian Misc. C o l l e c t i o n s 128 (9): 1-201. Marshall, S.M. and A.P. Orr. 1955. The Biology of a Marine Copepod. Calanus finmarchicus (Gunnerus). O l i v e r and Boyd. Edinburgh and London. Marukawa, H. 1921. Plankton l i s t and some new species of Copepods from the northern waters of Japan. B u l l . l ' I n s t . Oce. No. 384. McEwen, G.C., M.W. Johnson and H.R. Folsom. 1954. A s t a t i s t i c a l a n a l y s i s of the performance of the Folsom Plankton sample s p l i t t e r , based upon test observations. Archiv fur meterorologie, Geophysik und Bioklimatology, Series A, 7: 503-527 (Reprinted as Scripps Inst. Oce. Contrib. No. 689). McGowan, J.A. 1960. The r e l a t i o n s h i p of the planktonic worm, Poebius meseres Heath, to the water masses of the North P a c i f i c . Deep-Sea Res. and Oce. Abst. 6 (2): 125-139. McLaren, I.A. 1963. E f f e c t s of temperature on the growth of zooplankton, and the adaptive value of v e r t i c a l migration. J . F i s h . Res. Bd. Can. 20 (3): 685-727. Minoda, Takashi. 1971. Pelagic copepoda i n the Bering Sea and the N.W. P a c i f i c with s p e c i a l reference to t h e i r v e r t i c a l d i s t r i b u t i o n . Mem. Fac. F i s h . , Hokkaido U. 18 (1/2): 1-74. 53 Nemoto, Takahisa. 1963. Some aspects of the d i s t r i b u t i o n of Calanus  c r i s t a t u s and C_. plumchrus i n the Bering and i t s neighbouring waters, with reference to the feeding of Baleen whales. S c i . Repts. of the whales Res. Inst., Tokyo 17:157-170. . and Kasuyo, Toshio. 1965. Foods of Baleen whales i n the Gulf of Alaska of the North P a c i f i c . S c i . Repts. Whales. Res. Inst., Tokyo 19: 45-51. Omura, N., S. Ohsumi, T. Nemoto, K. Nasu and T. Kasuyo. 1969. Black Right whales i n the North P a c i f i c . S c i . Repts. whales Res. Inst., Tokyo 21: 1-78. Pandyan, A.S. 1971. Food and trophic r e l a t i o n s h i p s of the develop-mental stages of Euchaeta japonica Marukawa and Calanus plumchrus Marukawa. Ph.D. Thesis, I n s t i t u t e of Oceanography, U n i v e r s i t y of B r i t i s h Columbia. Parsons, T.R., R.J. LeBrasseur, J.D. Fulton and O.D. Kennedy. 1969. Production Studies In the S t r a i t of Georgia. Part I I . Secon-dary Production Under the Fraser River Plume, February to May, 1967. J . exp. mar. B i o l . E c o l . 3: 39-50. Parsons, T.R,, K. Stephens and R.J. LeBrasseur. 1969. Production Studies i n the S t r a i t of Georgia. Part I. Primary Production Under the Fraser River Plume, February to May, 1967. J . exp. mar. B i o l . E c o l . 3: 27-38. Pickard, G.L. 1956. Surface and bottom currents i n the S t r a i t of Georgia. J . F i s h . Res. Bd. Can. 13 (4): 581-590. 54 Pickard, G.L. 1963. D e s c r i p t i v e P h y s i c a l Oceanography. Pergamon Press L t d . , London. Re d f i e l d , A.C. and A l i c e Beale. 1940. Factors determining the d i s -t r i b u t i o n of populations of chaetognaths i n the Gulf of Maine. B i o l . B u l l . 79 (3): 459-487. R u s s e l l , F.S. 1935. On the value of C e r t a i n Planktonic Animals as Indicators of Water Movements i n the Eng l i s h Channel and North Sea. J . Mar. B i o l . Ass. U.K. 20: 309-331. , 1939. Hydrographical and B i o l o g i c a l Conditions i n the North Sea as Indicated by Plankton Organisms. Jour, du Cons. Int. pour l'Exp. de l a Mer 14 (2): 171-192. Sherman, Kenneth and E. Schaner. 1963. P o n t e l l i d copepods as i n d i c a -tors of an oceanic in c u r s i o n over George's Bank. E c o l . 49 (3): 582-584. Snedecor, G.W. and W.G. Cochran. 1967. S t a t i s t i c a l Methods. Iowa State U n i v e r s i t y Press, Ames, Iowa. Sverdrup, M.U., M.W. Johnson and R.H. Fleming. The Oceans, Their Physics, Chemistry and General Biology. P r e n t i c e - H a l l , Inc., Englewood C l i f f s , N.J. Tanaka, 0. 1954. Note on Calanus tonsus Brady i n Japanese waters. J. Oce. Soc. Jap., 10(1): 31-39. . 1956a. Further note on Calanus tonsus Brady i n Japanese waters. J . Oce. Soc. Jap., 12 (2): 49-52. 55 Tanaka, 0. 1956b. The pelagic copepods of the Izu region, middle Japan. Systematic account. I. Families Calanidae and Eucalanidae. Publ. Seto. Mar. B i o l . Lab. 5 (2): 251-272. T u l l y , J.P. and A.J. Dodimead. 1957. Properties of the water i n the S t r a i t of Georgia, B r i t i s h Columbia, and i n f l u e n c i n g f a c t o r s . J . F i s h . Res. Bd. Can. 14 (3): 241-319. Waldichuk, M. 1957. Physical Oceanography of the S t r a i t of Georgia, B r i t i s h Columbia. J . F i s h . Res. Bd. Can. 14 (3): 321-486. Watson, N.H.F. and B.W. Smallman. 1971a. The physiology of diapause i n Diacyclops navus Herrick (CrustacearCopepoda). Can. J , Zool. 49 (11) : 1449-1454. , 1971b. The r o l e of photoperiod and temperature i n the induction and termination of an arrested development i n two species of freshwater cyclopoid copepods. Can. J . Zool. 49 (6): 855-862. Wilson, C.B. 1950. Copepods gathered by the U.S. F i s h e r i e s Steamer "Albatross" from 1887-1909, c h i e f l y i n the P a c i f i c Ocean. B u l l . U.S. National Mus. #100, 14 (4): 141-441. Woodhouse, CD., J r . 1971. A study of the e c o l o g i c a l r e l a t i o n s h i p s and taxonomic studies of two species of the Genus Calanus (CRUSTACEA:COPEPODA). Ph.D. Thesis, I n s t i t u t e of Oceanography, U n i v e r s i t y of B r i t i s h Columbia. 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.831.1-0101212/manifest

Comment

Related Items