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Systematic and ecological studies on copepoda in Indian Arm, British Columbia Shan, Kuo-Cheng 1962

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SYSTEMATIC AND ECOLOGICAL STUDIES ON COPEPODA IN INDIAN ARM, BRITISH COLUMBIA by KU0-CHMG SHAN B. Sc., Taiwan Normal University, China, 1956 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in the Department of Zoology We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA October, 1962 In presenting t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree a t the U n i v e r s i t y of B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t freely-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 of 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 t h a t copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be allowed without my w r i t t e n permission. Department of Zoology  The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada. Date OCLATC^ // . / i ABSTRACT A survey of the biological oceanography in Indian Arm, a fjord-type inlet near Vancouver, B. C, has been carried out during the past several, years by the Institute of Oceanography of the University of British Columbia. The present study deals with four species of Copepoda, and their distribu-tion and relationships to water properties. A systematic study of four of the most abundant pelagic calanoid copepods was undertaken, namely, Calanus sp., Gaetanus armiger Gdesbrecht, Pareuchaeta japonica (Marukawa), and Metridia sp... Some suggestions on the taxonomy of the four species in the local area are made. The l i f e history stages of Calanus sp. and Gaetanus armiger have been briefly described. Life cycles of these two species within a year have been evaluated. Water properties represented by temperature, salinity, and dissolved oxygen have been viewed in relation to the distribution of Calanus sp. and Gaetanus armiger. Adult males and females of both species are demonstrated as inhabiting waters with different ranges of properties. Stage V of the juveniles of Calanus inhabits conditions intermediate between those of males and females. Stage I of the juveniles of Gaetanus armiger occurs in a restricted range of properties, but the range widens with each successive stage. The distributions of copepodid stages and adults of the two species are shown to conform, in general, to the ranges of properties to which relationships have been demonstrated. i i ACKNCfWIEDGMENT The author would like to express his gratitude to his supervisor Dr. B. M. Bary, Associate Professor of Biological Oceanography, for his suggestions, instruction, and encouragement, and everything concerning the necessity for the completion of this thesis. Deeply appreciation is also to his graduate committee members; Dr. B. M. Bary, Chairman; Dr. G. L. Pickard, Professor of Physics and Director of the Institute of Oceano-graphy; Dr. P. A. Dehnel, Associate Professor of Invertebrate Zoology; without their consultation and criticism, this thesis may not be so arranged. The Department of Zoology and the Institute of Oceanography of the University of British Columbia granted assistantships to the author since he came to the university, enabling him not to have any financial difficulty in his study i n the past years. The Institute of Oceanography provided the material, data, and facilities for this study. These, not only to the author himself, but also to the country where he i s from, are great grant and will be seeded in his mind forever. o i i i TABLE OF CONTENTS ABSTRACT --• i ACKNOVilEDCaffiKT i i TABLE OF CONTENTS _ _ - - _ _ _ - • - i i i SECTION PAGE I INTRODUCTION 1 II MATERIAL AND METHODS 2 III SYSTEMATICS - - - 4 Order. Copepoda 5 Suborder Calanoida - - - - - - - - - - - - - - - - - - - - - 6 Family Calahidae - - - - - - - - - - - - - - - - - - 7 Genus Calanus - - - - - - - - - - - - - - - - - - - - - - 8 Calanus sp. - -. - - -'- - - ----- - - - - - - - - - - 9 Discussion of Calanus sp. - - - - - - - - - - - - - 1 2 Family Aetideidae — _ _ _ _ _ ; _ ; 18 Genus Gaetanus - - - - - - - - - - - - - - - - 19 Gaetanus armiger Giesbrecht - - i — _ _ _ _ _ _ _ _ 20 Discussion of Gaetanus armiger - - - - - - - - - - - 2 3 Family Euchaetidae - _ _ - - - - - _ - - - - - - _ _ - - - 2 4 Genus Pareuchaeta - - - - - - - - - - - - - - - - - - - - 25 Pareuchaeta japbhica (Karukawa) 26 Discussion of Pareuchaeta japonica -29 Family Metridiidae • - • _ - _ _ - _ - _ 30 Genus Ketridia - - - - - - - - - - - - - - - - - - - - - - 3 1 Metridia sp'. - - - - - - ; 32 Discussion of Metridia sp. 34 IV LIFE HISTORIES AND'- CYCLES 41 Life history stages "of Calanus sp. _ _ _ _ _ _ _ _ _ _ _ 42 Life cycles of Calanus sp. 44 Life history stages of Gaetanus armiger - - - - - - - - - - -i,46 Life cycles of Gaetanus armiger - - - - - - — - — - - - - 49 V OCEANOGRAPHIC CONDITIONS --. • -;51 Temperature - - - - - - - - - - - - - - _ - - _ - _ _ - - - - 52 Salinity ; _ 53 Dissolved Oxygen - - - - - - - - - - — - - - - - - - - - --54 Discussion of Oceanographic Conditions - - - - - - — - - - 55 iv TABLE OF CONTENTS (Continued) SECTION PAGE VI TEMPERATURE, SALINITY, AND OXYGEN IN RELATION TO COPEPODS - - 58 Temperature-Salinity-Plankton - - — - - - - 60 Calanus sp. - - - - - - - - - - - - - - - - - - - - - - - - 60 Gaetanus armiger - - - - - - - - - - - - - - - _ _ _ _ _ 62 Oxygen-Salinity-Plankton - • — 63 Calanus sp. - - - _ _ - - _ _ - - - - - - - - _ - _ - - - - - 63 Gaetanus armiger - - - - - - - - - - - - - - - - - - - - - - 64 Oxygen-Temperature-Plankton - - - - - - - - - - - - - - - - - 65 VII DISTRIBUTION OF COPEPODS 66 Distribution of Calanus sp. . — - - 66 Distribution of Gaetanus armiger - - - - - - - - - - - - - - 67 VIII DISCUSSION (The Distribution of Copepods in relation to Oceanographic Conditions) - - - - - - - - - - - - - - - - - - 70 IX SUMMARY : 79 X LITERATURE CITED 82 XI LIST OF TABLES 88 XII EXPLANATION OF ILLUSTRATIONS , 108 1 I. INTRODUCTION In the north-east Pacific and more especially along the coast of British Columbia, studies on the systematics of Copepoda have been carried out by Campbell (1929, 1930, 1934a, 1934b), Johnson (1938, 1940), Johnson and Olson (1948), Davis (1949), Le Brasseur (1954), Bowman (1955), Cameron (1957), and Legare (1957). A few of these studies include l i f e histories (Campbell, 1934a; Johnson, 1936, 1938, 1939; Johnson and Olson, 1948). Some concern distribution in relation to oceanographic factors (Cameron and Mounce, 1922; Le Brasseur, 1955; Cameron, 1957J and Legare, 1957), but very few deal with seasonal distribution (Johnson, 1932). The above studies have included numerous species usually from compar-atively large areas. In the present study, a detailed survey covering the seasons over about one and: a: ha"_f" years, during I960 and 1961, has been made of a small area, namely Indian Arm, an inlet near Vancouver, B. C. (Fig. I - l ) . Four species of Copepoda have been studied; they are Calanus sp., Gaetanus armiger, Pareuchaeta japonica, and Metridia sp.. The Morphological characters have been described and variation during the year noted. The male and copepodid stages of one species, Gaetanus armiger, have been described for the f i r s t time. Ecological information has been obtained for two of the four species, namely, Calanus sp. and Gaetanus armiger. This information includes the vertical and longitudinal distribution during the period of December, I960 to September, 1961^in Indian Arm, and the relationships shown by the species to oceanographic changes. 2 II.- MATERIAL AND METHODS In recent years, the Institute of Oceanography of the University of British Columbia has been investigating the biological oceanography of Indian Arm, near Vancouver. This inlet is about twenty-two kilometres in length and slightly more than one kilometre in average width. Its long axis runs roughly north and south. It joins Burrard Inlet (Vancouver Harbour) at its southern end and through this connects with the Strait of Georgia (Fig. I - l ) . Zooplankton collections and observations of the oceanographic properties on temperature, salinity, and dissolved oxygen were made at monthly intervals from May, I960, to September, 1961, at selected stations (Fig. 1-2). The temperature was observed using reversing thermometers attached to Nansen bottles. The Nansen bottles collected water samples for salinity and dissolved oxygen determinations. Zooplankton samples were collected using the Clarke-Bumpus sampler (Clarke and Bumpus, 1950) with nets of 0.40mm mesh aperture (No. 2 mesh) and 0.12mm mesh aperture (No. 10 mesh). The samples were fixed and preserved with 40$ formaldehyde (buffered with borax) added to make up a U% strength solution with sea water. Samplers were set on the wire at positions to give depth intervals of 30m when towed horizontally (Fig. 1-2). Other levels were occasionally added i n order to provide more detailed informa-tion. Duration of the tows was between ten and fifteen minutes at a speed of about two knots. The samplers can be opened and closed at the selected depths. A flow-meter provides a means of estimating the volume of the water filtered. Thus, each sample can be treated quantitatively. A l l the copepodid stages can be caught by the 0.12mm mesh. Most zooplankton samples were quite large, so that subsampling was necessary. The vacuum-assisted subsampler (McHardy, 196l) was used for this purpose. Copepods were removed from the subsamples and counted. A l l the analyses are reported as numbers of copepods collected per cubic metre of water filtered. Specimens for detailed morphological study were dissected and mounted in polyvinyl-lactophenol medium (Salmon, 1949) to which a few drops of 1% fast green, chlorazol black, or lignin pink were added and mixed before the specimens were put into i t . Chlorazol black is a good stain for this purpose, especially for showing joints and setae in the smaller specimens. Sometimes specimens were unstained and mounted directly in a non-resinous mounting medium prepared by the General Biological Supply House, Chicago, Illinois. This medium is rapid to use for whole specimens and provides mounts of high transparency. Occasionally, the specimens were stained with carmalum (Mayer), and mounted in Canada balsam after dehydrating. A l l measurements were made from unmounted, preserved material, but limbs were placed under a cover-glass. Measurements were made with the aid of a compound microscope and an ocular micrometer (scaled in a hundred divisions) calibrated against a stage micrometer. A l l drawings were made with the aid of a camera lucida. Each diagram had a scale included at the time i t was drawn. Photoplates were made using a Leica 35mm. camera attached to a micromirror reflex and 1/3 X adapter. The scales on the photos were drawn later on the negatives. I l l , SISTEMATICS The systematic position of each of the four species described Indian Arm is follows: Phylum Arthropoda ' Class Crustacea Order Copepoda Suborder Calanoida Section Amphascandria Family Calanidae Genus Calanus Leach, 1819 Calanus sp. Family Aetideidae Genus Gaetanus Giesbrecht, 1888 Gaetanus armiger Giesbrecht, 1888 Family Euchaetidae Genus Pareuchaeta A. Scott, 1909 Pareuchaeta japonica (Marukawa),.1921 Section Isokerandria Section Heterarthrandria Family Metridiidae Genus Metridia Boeck, 1864 Metridia sp. 5 Order Copepoda Aquatic Crustacea may be free-swimming, benthonic, commensal, semi-parasitic, or parasitic, in freshwater and marine habitats. Body divided into three parts: head, thorax, and abdomen. Head and thorax usually combined as cephalothorax or metasome. Abdomen with a pair of furcae (caudal rami), the whole named the urosome. Body more or less distinctly segmented, except in a few parasitic genera, and vd-thout true shell gland. Head or cephalosome often covered with a carapace; one or more thoracic segments may develop paired dorsal plates. Head unsegmented, often completely fused with the fi r s t thoracic segment. Eyes often present, sometimes with cuticular lenses. Rostrum and frontal organs with sensory hairs present. Genital pores situated on the last thoracic segment (or genital segment) which i s usually regarded morphologically as the f i r s t and second segment of the urosome. Six pairs of appendages on the head, namely, f i r s t antenna, second antenna, mandible, first maxilla, second maxilla, and maxilliped; five pairs of thoracic appendages, the swimming legs; and one pair on the abdomen, the furcae or caudal rami, posteriorly on the last, anal segment. Sars (1903) suggested the following seven suborders of Copepoda: Calanoida, Harpacticoida, Cyclopoida, Motodelphyoida, Monstrilloida, Caligoida, and Lernaeoida. Wilson (1932) added a further suborder, Arguloida, to these. The species of Indian Arm studied belong in suborder Calanoida. 6 Suborder Calanoida Metasome consists of head and five thoracic segments; i t may be consid-erably depressed, and is much wider than the urosome. Female genital open-ings paired, on the ventral surface of the genital segment; the male genital opening single, placed asymmetrically, on the left side. First antennae elongated, many segmented, symmetrical in female, often asymmet-rical and transformed into a grasping organ in male. Second antennae bi-ramus, usually with two-segmented endopodite, and seven-segmented exopodite. Mandibles generally have masticatory teeth on the coxopodite, and well developed endopodite and exopodite. First maxillae with several lobes on the coxopodite, usually three inner lobes and two external lobes; endo-podite segmented, exopodite unsegmented. Second maxillae and maxillipeds uniramus and furnished with curved setae or claws. Of the five pairs of swimming legs, the four anterior pairs always biramus, the f i f t h often reduced or missing in female, modified into prehensile organs in male. Caudal rami with three to five setae on each, sometimes with a slender bristle. Rose (1933) subdivided the suborder Calanoida into three sections under which the families are listed. Section Amphascandria; The f i r s t antennae symmetrical but different in structure in males and females; those of the male have more sensory organs on each segment, but less number of segments than those of female. Mouthparts of male more or less reduced compared with those of the female. A l l marine. Families in this group: Calanidae, Eucalanidae. Paracalanidae, Pseudocalanidae, Aetideidae, Euchaetidae, Phaennidae, and Scolecithridae. 7 Section Isokerandria; First antennae and mouthparts of both sexes similar in feature. A l l marine. Families in this group: Diaixidae, Stephidae, Pseudocyclopidae, and Platycopidae. Section Heterarthrandria: First antennae of the male asymmetrical, one side being transformed into a prehensile organ with a geniculate articulation. Second antennae of the male slightly asymmetrical. The f i f t h legs always present in males and females and much alike i n both sexes. Mouthparts identical in both sexes. Marine and freshwater habitats. Families in this group: Centropagidae, Temoridae, Metridiidae, Heterorhabdidae, Arietellidae, Pseudocyclopidae, Gandaciidae, Pontel-lidae, Parapontellidae, and Acartiidae. The species from Indian Arm belong to the families of Calanidae,' Aetideidae, Euchaetidae, and Metridiidae. Family Calanidae Metasome elongate-oval; urosome moderately slender, and about one third the length of metasome. Head usually separate from the thorax, frontal part round or. protruded in dorsal aspect, sometimes with a median crest or spine. Rostrum always present, consisting of two soft, ventro-posteriorly curved filaments. Thoracic segments well separated; the posterior corners of the f i f t h (last) segment rounded, slightly pointed, or spined. Urosome four-segmented in female, five-segmented in male. Furcae comparatively short, with six setae on each. Eyes simple, very small, and subventral. 8 First antennae twenty-five-segmented, with comparatively short, uniform bristles; each of the twenty-third and twenty-fourth segments with an unusually long, stout, densely plumose seta. Second antennae with endo-podite and exopodite of equal lengths. Mouthparts normal, but slightly reduced in male; distal bristles of the second maxillae and maxillipeds not modified. A l l swimming legs three-segmented on endopodite and exopodite of both sexes,(except Bathycalanus); the external margin of the third exopodal segment with only two spines; inner margins of the coxopodite of the f i f t h legs smooth or serrated; f i f t h legs of the male more or less modified and asymmetrical, the lef t side possessing, a longer exopodite. This family comprises five genera; Calanus, Bathycalanus, Megacalanus, Neocalanus, and Calanoides (Brodsky, 1950). One species of the genus Calanus has been studied from Indian Arm. Genus Calanus Leach, 1819 Head either fused or separated from the fi r s t thoracic segment and slightly carinated dorsally in the male; frontal margin obtuse, more or less projecting between the insertions of the fi r s t antennae; two rostral filaments. The posterior corners of f i f t h thoracic segment rounded. Urosome symmetrical; genital segment protrudes slightly on the ventral side.. The setae on the furcae symmetrically arranged on both sides, the second inner one the longest. 9 First antennae generally longer than the total body length, and longer in males than in females. Exopodite of the second antenna with seven segments and of equal length to the endopodite. Eight groups of teeth on the masticatory edge of the mandible. Seta on the external edge of each of the two distal segments of maxillipeds in male remarkably developed and densely plumose. The five pairs of swimming legs comparatively slender; endopodites well developed, but considerably shorter than the exopodites. The external margin of the exopodal segments with one, one, and two spines on, respect-ively, the f i r s t , second, and third segments. The distal spine of the third exopodal segment of the anterior four pairs of legs elongate and scalpel-like. The f i f t h legs of females similarly segmented to the other legs; of males, the left limb modified as a grasping organ and longer than the right. The inner margin of the coxopodite of the f i f t h leg may be denticulated or smooth. Hotseta on the inner margin of the exopodal segments of the f i f t h limbs in males. Order Copepoda Suborder Calanoida Section Amphascandria Family Calanidae Calanus sp. Plates: II, III, X, XI. Specimens of two size groups of Calanus have been examined from Indian Arm. The two size groups are sufficiently similar in many of their morphological characters to make i t difficult to distinguish between them. However, there are differences in the head shapes in females and the proportional lengths of segments of the f i f t h limbs in males so that some distinction is required. 10 Accordingly, in the present study they are referred to as the "small" and the "large" forms (see Discussion of. Calanus sp.). FEMALE: Metasome oval elongate, but slenderer in the small form (Figs. 11-13, 15.)J bead separate from the f i r s t thoracic segment, frontal portion smoothly rounded in lateral aspect (Fig. III-4), but more convex in small form (Fig. III-l). The f i f t h thoracic segment separate from the fourth, its posterior corners rounded in lateral view (Figs. 111-1,4)• Urosome about one-third of the length of metasome; genital segment about as long as the following two segments combined, slightly and symmet-rically swollen anteriorly to the middle portion in dorsal view (Figs. 11-13, 15). Furca longer than anal segment and about twice as long as wide, each with six slender plumose setae on the distal margin (Figs. II-13, 15). The f i r s t antenna (Fig. II-l) longer than the total body length by two to three segments (Figs. 111-1,4). The mouthparts (Figs. 11-3,5, 7,9, 11) similar to the description for the genus. The coxopodite of each of the f i r s t to fourth swimming legs (Figs. II-17, 18, 19, 20) with a seta on its inner margin, but denticulated on the f i f t h (Figs. III-5, 6, 7, 8). The basipodites of the f i r s t leg without external spine, but with a curved seta at the inner distal corner (Fig. 11-17); on the second and third legs, a spine i s present on the external distal corner (Figs. 11-18, 19), but this spine is barely visible on the basipodites of the fourth and f i f t h legs (Figs. 11-20, III-5, 6, 7, 8). The number of setae on the third endopodal segment of the f i f t h leg varies with size; usually there are six, two on,each of the inner, distal, and outer margins (Fig. Ill-8) of the large form; in the smaller specimens, 11 there are fiv e , only one seta being present on the outer margin (Fig. I I I -5); some specimens of intermediate size, may have five setae on both legs (Fig. III-6), or five setae on one leg and six setae on the other (Fig. IH-7). MALE: Morphologically similar to the female, but smaller i n size. Head sharply defined from the. f i r s t thoracic segment by a slight, gibbous projection across the dorsal surface (Fig. Ill-10); a dorsal organ located mid-dorsally at the foremost one-third (Figs. 11-14, 16; III-9, 10, 11). Frontal part of the head more prominent than i n female. Urosome five-segmented (Figs 11-14, 16), the second segment being the longest. The f i r s t antenna (Fig. II-2) longer than the total body length, exceeding the di s t a l end of the furca by more than four segments (Figs. III-9, 10, l l ) ; subapical plumose setae on the twenty-third and twenty-fourth segments subequal i n length and less developed than i n female (Fig. I I - l ) . Mouthparts (Figs. II-4, 6, 8, 10, 12) slightly reduced compared with the female 1s. SwinmrLng legs, except the f i f t h , similar to those of female. The f i f t h legs (Figs. Ill-12, 13, 14) asymmetrical, the l e f t leg being longer than the right; the right exopodite about as long as the combined lengths of the two proximal exopodal segments of the l e f t limb i n the large form (Fig. Ill-14), and slightly shorter i n small form (Fig. Ill-12). The endopodite about the same length on both sides; the di s t a l end of the l e f t endopodite reaches to, or exceeds, the mid-length of the second exopodal segment i n large form (Fig.' 111-14), but reaches to one-third, or less, i n 12 the small form (Fig. 111-12). The third l e f t exopodal segment pear-like and joined to the second exopodal segment by a membranous articulation (Figs. Ill-12, 13). There are no setae on the inner margin of the exopodite. The total body lengths are 3.2 to 4.2mm (26 measurements) for large form females, 3.5 to 4.0mm (5 measurements) for large form malesj for small form females, they are 2.3 to 3.3mm (21 measurements) and 2.5 to 3.3mm (20 measurements) for small males. The proportional lengths of the segments of the metasome, urosome, and f i r s t antenna to the total lengths of each of these body parts have been shown in Tables 1, 2, and 3- (see Discussion of Calanus). Discussion of Calanus sp. The Indian Arm specimens can be subdivided into two size groups within the population. The large form i s similar to the species C. glaci a l i s Jaschnov (Jaschnov, 1955)> but i s smaller (3.2 to 4.2mm for females, 3.5 to 4.0mm for males), whereas the females of C. glacialis are 4.3 to 5.5mm, and males 4.7 to 5.2mm. The small form (from Indian Arm) i s closest to the description given for C. pacificus by Brodsky (1950). It differs, however, i n having a relatively longer f i f t h l e f t endopodite i n the malesj i t extends to about one-third of the length of the l e f t second exopodal segment of the .fifth leg, whereas i n C. pacificus the l e f t endopodite seldom extends beyond the d i s t a l end of the f i r s t exopodal segment (Brodsky, 1959). The large form does not appear to. be C. finmarchicus (Gunnerus), described from the North Atlantic, because the toothed inner margin of the coxopodite of the female's f i f t h legs i s strongly concave (Fig. I l l - 8 ) 13 compared wit h an almost straight or slightly concave line i n C. finmarchicus (Sars, G. 0., 19-03)- The small form does not appear to be C. helgolandicus (Claus) mainly because the shape of the forehead i s not protuberant and bluntly pointed, but i s smoothly rounded (Fig. I I I - l ) . The two size groups are differentiated by length-frequency histograms of the metasome (Fig. X - l , 2). Measurements were made of specimens from a range of depths, for each month during the period from October, I960 to September, 1961. The modes are at 2.3mra for females and 2.2mm for males of the small form; 2.9mm for females, and 2.8mm for males of the large form. Size overlap appears to occur at 2.6mm i n females, and between 2.5mm and 2.6mm i n males. That two or more size groups can occur to-gether i n a population i s familiar to zooplanktologists since the beginn-ing of this century (Currie, 1918; Bogorov, 1933; Rees, 1949; Russell, 1951; Marshall and Orr, 1955; Grainger, 1961). I t i s possible that i n Indian Arm the large and small forms may also represent two size groups from within a population; or they nay be representatives of two different populations of one species of Calanus. Or i t i s possible they may be distinct forms, e.g. species. Body length alone, however, may not be sufficient to decide between these p o s s i b i l i t i e s for the specimens. The relationship between the body length and the number of teeth on the inner margin of coxopodite of f i f t h legs has been evaluated i n Table 4 for females, and i n Table 5 for males. These tables indicate that the number of teeth on the l e f t f i f t h coxopodite varies widely; there may be a relationship to the length of metasome, namely that i n the small^females the highest frequency of occurrence i n the number of teeth i s at 22, and for large females, between 22 and 25 teeth, possibly with 14 25 predominating. Among the males, data are sufficient to indicate that among the small specimens the highest frequency occurred between 20 and 23 teeth; a mode is not apparent for the few large males available. There is much overlap in the range of tooth-numbers in the specimens and a clear differentiation between the size groups does not seem possible on the data available. Another character, which has been used in diagnoses of Calanus species, i s the number of setae on the external margin of the third endopodal segment of the f i f t h limbs in females (Jaschnov, 1955). In Table 6, the number of these setae in females are shown in relation to length of meta-some and months of the year. It is to be noted that there is a tendency for the metasome length to increase monthly from October, I960 to February, 1961, and to decrease monthly thereafter. It would seem from Table 6 that the smaller specimens were seldom with more than one seta in this position. Large specimens often had two setae during the winter and spring seasons but there was much variation. The differences between the size-groups may be a consistent feature, but within the larger specimens, the variation appears too great for the number of setae to be significant systematically. Thus whether one, one-and-two, or two setae occur on the external margin of the third endopodal segment of the f i f t h legs in females does not seem to be consistent and because.of this the character could not be used in the differentiation of the groups. The shape of the female's head has been used as a character to distin-guish the two forms C. finmarchicus and C. helgolandicus (Rees, 1949; Marshall and Orr, 1957). The small specimens from Indian Arm differ slightly in this character from the large ones. In specimens of both sizes groups, 15 the head is smoothly rounded anteriorly. But in the small form (Fig. III-1), the curvature i s more strongly convex antero-dorsally than in the large form (Fig. I l l - 3 , 4). This gives the frontal end a rather more protuberant appearance than.in the large form. The character appears to be a consistent one as shown in Table 7 where the head shape i s tabulated i n relation to length of the metasome, I.e. for size. Table 7 indicates two points: f i r s t l y , the females can be distinguished by the shapes of the forehead In a way that two size groups can be obtained which coincide closely with the length-frequency histograms, shown in Fig. X-1. This indicates that the shape of the head may be aiisatisfactprycmeans, of distinguishing between the specimens of the two groups. In C. finmar- chicus and C. helgolandicus, however, head shape i s generally not considered sufficient in itself as a diagnostic character. Possibly i t is not suffi-cient in the present instance either. Secondly, the overlapping size range. indicated by the head shape (2.4 to 2.6mm) is wider than the 2.6mm indicated by the histograms, but only a few specimens are concerned.. Head shape may be a useful character, but i t may not in itself be sufficient to counteract the previous considerations based on numbers of setae and numbers of teeth on the f i f t h limbs of the females. The position to which the distal end of the endopodite of the left f i f t h leg reaches on the second segment of the left f i f t h exopodite in males is also regarded as a diagnostic character. The position i s about one-third the length of the second exopodal segment in the small form, and about one-half in the large form. Table 8 shows that this is a consistent feature in size-groups. 16 The lengths, of the left f i f t h endopodite of males were plotted against the lengths of exopodite of the same limb (Fig. X-3); the lengths of the le f t f i f t h exopodite were also plotted against the lengths of the right f i f t h exopodite (Fig. X-4). The resulting diagrams could be interpreted to indicate a linear relationship between lengths of one limb, or part of a limb, and the other. On the other hand, in both figures, the proportional lengths of one limb to the other in the large form f a l l on one side (the lower) of the calculated regression line, whilst the proportional lengths for the small form tend to f a l l on the other (upper) side. This difference coincides with the size differences as shown by Table 8, and could be used to differentiate systematically between the forms, especially, as the f i f t h limbs of males are generally regarded in copepods as providing good diagnostic characters. Data are probably too few to be conclusive, but they are suggestive that proportional lengths, as illustrated, may provide a means of differentiating the forms systematically. Seasonal occurrences are indicated by Tables 7 and 8. Although data may not be sufficient to be convincing, i t would seem that the greater abundance of the randomly selected specimens of both forms was in different seasons; the large form appears to be more common in spring and summer, and the small form in summer and f a l l . Previously, in this account, the proportional lengths of the segments of the f i r s t antenna, metasome, and urosome of small and large forms of Calanus sp. were tabulated (Tables 1, 2, and 3); these are illustrated in Figs. XI-1, 2, 3, 4. From a perusal of the diagrams i t is clear that although differences exist between the forms these do not appear to be large. It is doubtful whether any systematic importance can be attached 17 to the differences (see Discussion of Metridia sp. and Figs. XI-5, 6, 7). From the discussion, there i s the possibility that in addition to size, two characters, namely, the head shape in the females, and the position on the second exopodal segment of the left f i f t h leg to which the distal end of the left f i f t h endopodite reaches in the male, may be used to differentiate between the two forms in Indian Arm. Other characters, namely, the number of setae on the distal endopodal segment of f i f t h leg in females, the number of teeth on the f i f t h coxopodite, the proportional lengths of the segments of the segments of fi r s t antenna, metasome, and urosome, do not show clear differentiation between the forms. On the basis of head shape in females and the structural differences in the male f i f t h limb, i t is possible to consider that two forms are present in Indian Arm. However, the other characters would not appear to support this. Furthermore, some specimens which were intermediate in size between large and small forms (Figs. III-2, 3, 10) appeared to possess other characters intermediate between the two. For example, in Fig. 111-13, the left endopodite of the male f i f t h limb reaches a position midway between the position for the small and large forms. In view of these intermediate forms and of the doubts raised above, further analyses on more material is needed. It seems desirable, therefore, to regard the species i n Indian Arm as Calanus sp. and to refer to the forms simply as "small" and "large" forms, pending further clarification. The relationships of the Indian Arm forms to the other, closely related species of Calanus from the northern hemisphere i s indicated in 18 Table 9 where several characters are compared. This table suggests that the large form has features common to G. glacialis and C. finmarchicus, and the small form -.to; C. pacificus. The table also suggests the several species may "grade" from one to another, perhaps i n a cline of variation. This could be an effect of temperature on morphological structure; Coker (1934) has shown i n freshwater copepods reared at lower temperatures that the spination changes and a spine develops i n l i e u of a seta on the outer border of the terminal segment of the endopod of the fourth limb. As far as the present study i s concerned, Table 9 appears to provide another reason for leaving the identification of the Indian Arm material open. Detailed investigation of -the shape of the head, the body length, the number of teeth on the f i f t h coxopodite, the lengths of l e f t and right f i f t h legs of males, and the number of females i n a population with different number of setae on the external margin of the third endo-podal segment.of f i f t h leg are needed. As well, these data should be studied i n relation to ecological factors of the species or forms from different regions and l o c a l i t i e s . Some ecological features of Indian Arm Calanus are discussed i n a later section. Family Aetideidae Body stout, metasome more or less swollen. Head fused with the f i r s t thoracic segment; forehead projects below into a heavily chitinised, b i f i d or simple rostrum. The last metasomal segment fused with the preceding segment and the latero-posterior corners produced. Urosome four-segmented i n female, five-segmented i n male. Anal segment very short. Furcae slightly longer than the anal segment, with four setae on di s t a l end of each. Eyes generally well developed, but may be wholly absent i n some cases. 19 First antennae in female of moderate length or comparatively short with the eighth and ninth segments fused; in male, slightly modified, some segments fused; sensory filaments occur on the proximal segments. Exopodite of second antenna longer than endopodite. Mouthparts in female normally developed. Distal segments of the maxillipeds reflexed. Mouth-parts in male considerably reduced. Swimming legs four pairs in female, five pairs in male. The f i f t h legs of male slender, right leg styliform and shorter than the l e f t . There are eighteen genera recorded in this family (Rose, 19335 Brodsky, 1950). The species from Indian Arm belongs to the genus Gaetanus. Genus Gaetanus Giesbrecht, 1888 Metasome with four visible segments; rostrum small, single pointed, or absent. . Antero-dorsally, on the median portion of the head, a single spine occurs which may turn downward, parallel to the front, or may pro-ject forward. The postero-lateral corners of the metasome produced into a pair of pointed processes or spines, but these may be absent i n males. The exopodite of the f i r s t leg two- or three-segmented; those of the second, third, and fourth legs three-segmented. The endopodite of the f i r s t leg unsegmented; that of the second leg two-segmented (sometimes partially fused together); and those of the third and fourth legs three7 segmented. The f i f t h legs of male five-segmented with a rudimentary endopodite on each. 20 Order Copepoda Suborder Calanoida Section Amphascandria Family Aetideidae Gaetanus armiger Giesbrecht, 1888 Plates: IV J V, VI. Gaetanus armiger Giesbrecht, 1888, 1892 Giesbrecht and Schmeil, 1898 Breeman, 1908 Scott, A., 1909 Sars, 1925 Mori, 1937 Davis, 1949 FEMALE: Body comparatively short and stout (Fig. IV-10). Urosome slightly longer than one-quarter the length of the metasome. The width of the metasome about one-third its length. Rostrum (Fig. IV-6) short, with single sharp point, projecting ventrallyj at the base of the rostrum two tiny hairs indicate the frontal organ. Dorsally and posteriorly to the frontal organ a small sharp spine curves parallel to the head slope (Fig. IV-6)j some specimens are without the spine, but a scar may be present; the length of the spine is about one-third the length between 0 its base and the frontal organ. There are two pairs of eyespots dorsally on the head. A sharp spine on each of the postero-lateral corners of the last metasomal segment extends at least to the mid-length of the genital segment. Urosome with four segments; the genital segment is the longest, swollen symmetrically at the mid-portion in dorsal view (Fig. IV-10), with two genital protuberances (Fig. IV-6) side by side ventrally; the remaining.three abdominal segments decrease in length progressively. The furca about equal in length to the anal segment. A small slender seta curves ventrally and posteriorly on the external distal margin of the furca (Figs. IV-6, 10). Numerous short, slender hairs occur on the 21 median surface of the furcae (Fig. IV-12)'; distally, the furca bears four slender plumose setae of almost equal length, of which one or more may-be branched (Fig. 17-12). The f i r s t antenna (Fig. IV-18) symmetrical with twenty-five segments; i t extends to the distal end of genital segment; the eighth and ninth segments may be fused when only twenty-four segments are visible. The second antenna (Fig. V-6) biramus, with the exopodite longer than the endopodite. Mandible (Fig. V-13) well developed; the masticatory edge of the coxopodite with a hook-like seta, six sharp conical teeth, and five larger molar teeth. Maxilliped (Fig. V-34) seven-segmented, with-out lamella on the elongated basal segment, but with three rounded em-inences, each with two slender setae on the inner margin, and an additional short strong spine on the distal one. The fi r s t swimming leg (Fig. VT-6) comparatively small; a row of long slender hairs present on the inner margin of the coxopodite and basi-podite; the endopodite unsegmented, with a short, protruding lobe on the ventral surface and a fringe of fine bristles towards the distal end of the lobe; the exopodite three-segmented, but the division between the proximal two segments may be incomplete. MALE: The male of this species does not appear to have been described. Body shape similar to that of female (Figs. IV-9, 11). The metasome about three times longer than the urosome. Urosome with four visible segments; the f i f t h urosomelt.'-segment very short, and almost embedded within the fourth segment (Fig. IV-ll). The furca with four distal setae and one slender, curved external seta. The second inner distal seta approximately one-22 quarter longer than the others which are subequal in length (Fig. IV-ll). First antennae (Fig. IV-19) symmetrical, with twenty-one visible seg-ments; the frontal surface of the segments with slender sensory filaments which progressively decrease in length from the proximal towards the distal segments. The coxopodite of the mandible reduced (Fig. V-14). First maxilla (Fig. V-21) reduced, the spines on the fi r s t inner lobe of the coxopodite remain only as six nodules. Second maxilla (Fig. V-28) also reduced, the inner lobes becoming numerous tiny papillae, but the distal two lobes remaining, with one seta on each. Maxilliped (Fig. V-35) slightly reduced, no eminences or setae on the inner margin of the pro-ximal segment and only two small setae on its distal end. The fi r s t four swimming legs similar to those of female. The f i f t h legs (Fig. VI-24) are asymmetrical, the left being slightly shorter. The coxopodite of the left side about twice the length of the right. The left endopodite rod-like, with a very small notch near i t s mid-length and a tiny spherical node with a tiny spine on the distal end. The left exo-podite three-segmented; the proximal segment about twice the length of the second segment; the distal segment spine-like with a small spine on the outer margin, at the distal two-thirds of its length. The right endopodite is pear-like with the swollen part distally. The right exo-podite three-segmented; the proximal segment about two times longer than the right basipodite; the second segment about two-thirds the length of the proximal segment, enlarged distally on the inner corner. The third segment spine-like, and about half the length of the second. The total body lengths are 2.9 to 3.2mm (24 measurements) for females, 2.8 to 3.1mm (11 measurements) for males. 23 The proportional lengths of the segments of the metasome, urosome, and fi r s t antenna to the total lengths of each of these body parts are shown in Tables 10, 11, and 12. Distribution: Davis Strait between Greenland and Labrador; Atlantic ocean west of the British Isles, near the Azores, and in the Gulf of Guinea; east coast of South Africa; Indian ocean; Malay Archipelago; Pacific ocean near northern Japan and about five-hundred miles west of the Galapagos Islands (Davis, 1949). Discussion of Gaetanus armiger Sewell (1948) summarized the species in the genus Gaetanus into three large groups according to the characteristics of the exopodite of the f i r s t legs, the length of the f i r s t antennae, and the shape and size of the lamella on the f i r s t segment of the maxilliped. The species in Indian Arm belongs to Sewell's second group. In this group, the exopodite of the f i r s t leg is incompletely divided into three segments (the division between the two proximal segments being incomplete) and the f i r s t segment i s without a marginal spine. In addition the f i r s t basal segment of the maxilliped is without a lamella. In this group, G. armiger Giesbrecht and G. major Wolfenden (=G. kruppii Giesbrecht; Vervoort, 1952) were recorded. The species from Indian Arm differs from G. kruppii by being much smaller 2.9 to 3.2mm in females, 2.8 to 3.1mm in males while G. kruppii measures 3.6 to 5.7mm in females, 3.7 to 5.6mm in males (Vervoort, 1952); the f i r s t antenna extends to the distal end of genital segment in the Indian Arm specimens while in G. kruppii i t extends to the end of the furcae; the 24 spines on the postero-lateral corners of the last ntetasomal segment in local specimens are long and straight extending at least to the mid-length of the genital segment, while in G. kruppii, they are small, and slightly curved ventrally. The characters of the male from Indian Arm are similar to the description of G. kruppii, especially in the structure of the f i f t h legs; they differ, however, in being much smaller in size and in having a shorter f i r s t antenna, which in the Indian Ann specimens is slightly longer than the metasome, while in G. kruppii i t extends to the middle of abdomen (Vervoort, 1952). A summary comparison of these two species is shown in Table 13. There i s no doubt that the Indian Arm specimens should be assigned to Sewell's second group of Gaetanus. Within this group, there appear to be no discrepancies between the female specimens described above and the descriptions given by Giesbrecht (1888, 1892) for Gaetanus armiger. On the other hand there are clear distinctions between the local specimens and G. kruppii. Therefore, the specimens from Indian Arm are assigned to Gaetanus armiger Giesbrecht. Family Euchaetidae . Head completely or partly fused with the fi r s t thoracic segment; ros-trum single, acutely pointed, f i f t h thoracic segment fused with the fourth. Urosome four-segmented; genital segment of female more or less protuberant ventrally. Furcae short, the outermost seta rudimentary, but an elongated, accessory seta occurs distally on the inner corner. First antennae symmetrical and slender, with long bristles extending 25 in different directions along the anterior edge; in males, strongly-developed sensory filaments occur towards the base. Second antenna and mandible normally developed. The exopodite of f i r s t maxilla curved inwards. The second maxilla and maxillipeds very powerfully developed and armed with long clawlike spines. The mouthparts in males much reduced. The swimming legs powerfully developed, resembling in structure those of the Aetideidae. The f i f t h legs absent in females, large and specialized in males. The female carries an ovisac. Three genera, Euchaeta, Pareuchaeta, and Validiviella, have been recorded in this family (Rose, 1933; Brodsky, 1950). The species in Indian Arm be-longs to the genus Pareuchaeta. Genus Pareuchaeta, A. Scott, 1909 Head more or less fused with the f i r s t thoracic segment. Posterior corners of the last thoracic segment densely clothed with long hairs. There is a genital protuberance extending posteriorly on the ventral surface of the genital segment. The spines at the apex of the maxillipeds fringed with short secondary spinelets ..(this character helps to dis-tinguish Pareuchaeta from Euchaeta in which they are long spinules). The endopodites of the f i r s t and second legs unsegmented; endopodites of the third and fourth legs, and a l l exopodites, three-segmented. Fifth leg absent in the female, present and biramus in the male in which the left f i f t h exopodal segment is short and rudimentary, and the right, bluntly pointed. The accessory setae at the inner distal angle of the furcae very slender, with a well marked "knee joint" not far from the base. 26 Order Copepoda Suborder Calanoida Section Amphascandria Family Euchaetidae Pareuchaeta japonica (Marukawa, 1921) Plate: VII Euchaeta .japonica Marukawa, 1921 Campbell, 1929 Mori, 1937 Davis, 1949 Pareuchaeta japonica Brodsky, 1950 FEMALE: Head partly separated dorsally-. from the f i r s t thoracic segment (Fig. VII-2). Rostrum pointed and prominent; the papilla of the frontal organ very small. The postero-lateral corners of the last thoracic seg-ment terminate in blunt points. Along the postero-dorsal margins of the last segment are tufts of long hairs. Urosome about two-fifths the length of the metasome. The genital segment protrudes ventrally and posteriorly; i t is symmetrically swollen from the dorsal aspect (Fig. VII'-l).. Anal segment very short, resembling an articulation between the penultimate segment and the furca. Furca about as broad as long, with a very small non-plumose seta distally on the external margin and four long terminal setae and one accessory curved seta posteriorly on the ventro-medial margin of each side. The second inner terminal seta about twice the length of the others; the accessory seta nearly as long as the total body length. The f i r s t antenna (Fig. VII-6), with twenty-four segments, extends to about the posterior border of the metasome. The second antenna (Fig. VII-8) has a longer exopodite than endopodite. The mouthparts (Figs. VII-10, 12, 14, 16) well developed, especially the mandible (Fig. VII-10) which has five groups of strong teeth and a setosed slender hook-like bristle on 27 the masticatory edge of the coxopodite. The swimming legs (Fig. VII-18, 19, 20, 21) are similar to those of Gaetanus i n structure, but much stronger. The endopodites of the f i r s t and second legs unsegmented (Figs. VII-18, 19). MALE: Head completely fused with the f i r s t thoracic segment (Figs. VII-3,4). The posterior comer of the last thoracic segment not pointed, but slightly angular; hairs absent from the dorso-lateral margins (Fig. VII-4). Urosome with five abdominal segments, the f i f t h very short, embedded i n the fourth segment (Fig. VII-3), and almost invis i b l e ; the postero-dorsal margins of the second, third, and fourth segments toothed (Fig. VII-3). The accessory setae on the furca comparatively short, about the length of the other d i s t a l setae, and curved almost i n a right angle (Figs. VII-3,4). The f i r s t antenna with twenty-two v i s i b l e segments (Fig. VII-7) and reaching to the d i s t a l end of the f i r s t abdominal segment. The second antenna (Fig. VII-9) similar to that of the female. The mouthparts (Figs. VII-11, 13,.15, 17) reduced both i n size and structure; the mandible (Fig. VII-11) with indications of teeth; the f i r s t maxilla (Fig. VII-13) without spines on the inner lobe, the second maxilla (Fig. VII-15) very small, the maxilliped (Fig. VII-17) without clawlike spines, but with slender setae. The swimming legs similar to those of the females, but the exopodite of the f i r s t leg i s three-segmented. The f i f t h legs (Fig. VII-22) highly modified; the l e f t f i f t h leg five-segmented with a rudimentary three-segmented endopodite on the second segment, the basipodite. The fourth 28 segment (the second exopodal segment), broadly rectangular; i t terminates in a projection or thumb at the inner distal corner (Fig. VII-5) which has two subequal prongs with coarsely dentate margins; a row of teeth ex-tends in a curving line from the medial prong along the dorsal surface of the segment to its proximal joint. The f i f t h segment (third exopodal segment) (Fig. VII-5) is dactyloform with a brush of long, fine hairs at the tip; between the dactyloform segment and the fourth segment, is a smooth, oval lobe, or appendicular lappet, and a larger pointed lobe; these lobes are covered with fine setae. This whale structure on the fi f t h leg is used for transferring the spermatophore to the female. The right fifth leg is slightly longer than the left; the endopodite is about the same length as the f i r s t exopodal segment, and not segmented; the second or distal exopodal segment is slender, curved, and bluntly ended (Fig. VTI-22). There i s no third exopodal segment on the right f i f t h leg. The total body lengths are 5.9 to 6.6mm (15 measurements) for females, 5.6 to 6.0mm (12 measurements) for males. The proportional lengths of the segments of the metasome, urosome, and f i r s t antenna to the total length of each of these parts are shown in Tables 14, 15, and-16. Distribution: Japan sea, Northern Japan, Vancouver Island region, and coast of Southern California (Davis, 1949). 29 Discussion of Pareuchaeta japonica This species has been described as a species of Euchaeta, namely Euchaeta japonica, by Marukawa (1921) for specimens from the Japan Sea. Marukawa noted that E., .japonica is distinct from E. norvegica on the structure of the last thoracic segment and genital protuberance. Campbell (1929) referred the specimens occurring in the Vancouver area to E. .japon-ica, and later (1934a), gave a description of thelpost embryonic development. Mori (1937) gave a brief description and some illustrations of specimens of E. japonica from the Japan Sea. Davis (1949) described E. japonica in the Northeastern Pacific; the features of his specimens agree with previous descriptions. The specimens from Indian Arm also agree in a l l characters with those described elsewhere and there would appear to be l i t t l e doubt that they can be assigned also to E. japonica. However, a taxonomic problem has arisen due to splitting of the genus Euchaeta into Euchaeta and Pareuchaeta (Scott, A., 1909). With (1915), Marukawa (1921), Campbell (1929, 1934a), Mori (1937), and Davis (1949) considered that these two genera are identical. Scott, A. (1909), Sars, G. 0. (1925), Rose (1933), Wilson (1932), Sewell (1948), and Brodsky (1950) considered they are distinct genera. The characters on which the genera have been distinguished concern the structure of terminal spines of the second maxilla (Fig. VII-14), the third exopodal segment of the male's left leg (Fig. VII-22), the accessory setae on the furca (Fig. VII-l), and the apical spines on the maxillipeds (Fig. VII-16). These characters are compared in Table 17. Study of the specimens from Indian Arm suggests that as well as the characters, in Table 17, the distal end of the second exopodal segment of 30 the right f i f t h leg in males of Pareuchaeta is blunt (Fig. VII-22) while in Euchaeta males i t is pointed. The female genital protuberance on the ventral side of the genital segment protrudes more or less towards pos-teriorly in Pareuchaeta (Fig. VII-2), while in Euchaeta i t either protrudes anteriorly or is perpendicular to the ventral surface. These characters are valid in separating the following species: P. barbata, P. bisinuata, P. bradyi, P. glacialis, P. gracilis, P. hanseni, P. .japonica, P. norvegica, P. propinqua, P. sarsi, P. scotti, and P. tonsa from E. acuta, E. hebes, S. marina, E. media, E. pubera, E. spinosa, and E. wolfendeni. On the basis of these differences i t seems likely that Euchaeta should be regarded as composed of the two genera Euchaeta and Pareuchaeta. In . view of this and the facts discussed above, the Indian Arm specimens are assigned to Pareuchaeta japonica. Family Metridiidae Body comparatively slender. The head well defined from the first thoracic segment, the rostrum produces two delicate plumose filaments. The f i f t h thoracic segment fused with the fourth, so that there are only five visible segments in the metasome. Urosome more or less elongated, with three visible segments in the female, five segments in the male. The furca comparatively broad, dorso-ventrally flattened. Eyes very small, and subventral. The f i r s t antennae of the female symmetrical, of the male asymmetrical. One of the male fi r s t antennae geniculated; both rami with well developed sensory filaments. The mouthparts normally developed. There are five pairs of swimming legs in both sexes. The endopodites and exopodites of the four anterior pairs 31 of legs a l l three-segmented. The f i r s t endopodal segment of the second leg peculiarly transformed as a hook-like structure. The f i f t h legs uniramus, small in female, larger and prehensile in male. The female does not carry eggs. There are three genera in this family; Metridia, Pleuromamma, and Gaussia (Brodsky, 1950). The species from Indian Arm belongs to the genus Metridia. Genus Metridia Boeck, 1864 Body slender and elongated, head separated from the f i r s t thoracic segment. The postero-lateral corners of the last thoracic segment rounded or slightly produced, but not spined. The rostrum projects ventrally, and has two filaments. The urosome narrow and elongated; genital segment does not protrude ventrally. The furca squarely truncated at the tip. The f i r s t antenna conspicuously attenuated, with the anterior edge of some of the proximal segments projecting into small denticles. The prehensile antenna of the male generally on the left side with sensory filaments of moderate size and uniform appearance. The exopodite and the endopodite of the second antenna subequal. The mouthparts and the swimming legs normally developed. 32 Order Copepoda Suborder Calanoida Section Heterarthrandria Family Metridiidae Metridia sp» Plates: VIII, IX. FEMALE: Head separated from the f i r s t thoracic segment, the fourth and f i f t h thoracic segments fused together, and the fifth thoracic sepxent bluntly pointed latero-posteriorly (Fig. VIII-2). The metasome slender (Fig. VIII-l), about three times longer than the greatest width; in lateral view (Fig. VIII-2) the dorsal side of the head almost spheri-cally rounded. The two rostral projections are small, with fine f i l a -ments. The urosome about two-thirds the length of the metasome, consis-ting of three free segments and a pair of furcae. The genital segment about twice as long as wide, genital pores slightly produced as a pair of oval papillae on the ventral surface. The furca slightly longer than the anal segment; with a seta at the mid-length of the outer margin and four setae at the distal end (Fig. VIII-l). The f i r s t antenna (Fig. VIII-5) with twenty-five segments, symmetrical, and clearly segmented except between the seventh and eighth, and sometimes the ninth and tenth segments; the total length extends slightly beyond the posterior end of the metasome, but does not reach half the length of the genital segment (Fig. VIII-2). The exopodite of the second an-tenna slightly longer than the endopodite (Fig. VIII-9). The mandible (Fig. VIII-10) well, developed with eight groups of teeth and a setose spine on the masticatory edge. The four anterior pairs of swimming legs (Figs. VIII-14, 15, 16, 17) slender, three-segmented.on each exopodite and endopodite. The f i f t h 33 leg (Fig. VIII-18) usually- four-segmented, but sometimes three-segmented (Fig. IX-4); the length of the distal setae on the terminal segment variable; on the three-segmented legs they are about the same length (Fig. IX-4), but on the four-segmented legs they gradually decrease in length from the inner towards the outer side (Fig. VIII-18). MALE: The general features of the body somewhat like those of the female, but much slenderer and with five segments on the urosome (Figs. VIII-3, 4). The f i r s t antennae (Figs. VIII-6, 7, 8) asymmetrical, one of the pair geniculated, usually on the left; the right instead of the left may be geniculated, but in very few specimens in proportion to the whole popula-tion; the ungeniculated antenna (Fig. VIII-6) with twenty-five segments and with sensory filaments,on most of the segments; the geniculated antenna (Fig. VIII-8) with twenty visible segments, the last four consisting of two fused segments each; the geniculate position occurs between the seven-teenth and eighteenth visible segments (i.e. between nineteenth and twen-tieth segments) . The mouthparts and the four anterior swimming legs similar to the female, but more or less reduced in size. The f i f t h legs asymmetrical (Fig. VIII-19); both left and right rami five-segmented. If the geniculated antenna is on the left side, the longer leg i s on the left, and vice versa; on the longer ramus, the coxo-podite is about half the length and the basipodite about twice the length of the corresponding segments of the short ramus (Fig. VIII-19a). The third segment of the longer leg with a short, slender seta and a long, strong, bluntly pointed spine on the mid-dorsal margin (Fig. VIII-19b); the spine is about the length of theCdistal segment of the same leg, with 34 small teeth on its posterior margin. The fourth and f i f t h segments of the longer leg foliaceous; the fourth segment about one-third the length of the fi f t h and with a small seta. The fif t h segment with one subapical and two apical setae. At the inner distal corner of the basipodite of the shorter leg, there i s a row of short, slender hairs. The third segment of, this leg is short, barely separated from the second segment of basipodite, and liiay bear one small seta (Fig. VIII-19c). The fourth segment almost the same length as the third, and with a seta and a strong, bluntly pointed spine of about the same length, on the inner margin (Fig. VIII-19d). The fi f t h segment of the shorter leg also foliaceous, about the same length as the f i f t h segment of the longer leg, but about two-thirds as wide, with two apical and one subapical setae. The total body lengths are 2.8 to 3.2mm (50 measurements) for females, 2.0 to 2.5mm (20 measurements) for males. The proportional length of the segments of the metasome, urosome, and the first antenna to the total length of each of these parts are shown in Tables 18, 19, and 20. Discussion of Metridia sp. Previously, the species inhabiting coastal waters of B. C. was regarded a s M. lucens Boeck (Campbell, 1929; Davis, 1949; Cameron, 1957; Legare, 1957). In the present study, the Metridia found in Indian Arm has been compared with specimens from the North Atlantic (M. lucens), and from Southern California (Metridia sp.; Eaterly. 1924). Brodsky (1950) described M. pacifica from the Northwest Pacific and 35 differentiated i t from M. lucens and M. boecki Giesbrecht (another Pacific species), on the shape of the head, number of segments i n the f i f t h legs of females, the lengths of the terminal bristles on these legs, the length of the furca i n relation to the anal segment and on the structure of the f i f t h legs of males (Table 21). These characters are discussed for the specimens from Indian Arm, Southern California, and North Atlantic, and compared with Brodsky's information on M. pacifica. The number of segments of the f i f t h leg of the females varies among the specimens from the several l o c a l i t i e s . Mori (1937) pointed out that the number of segments of the f i f t h leg and the shape of the foot of the adult females from Japanese waters varied according to the stage of maturity of individuals. This appears to be true also for specimens from B. C, North Atlantic, and Southern California. The number of segments of the f i f t h leg were determined for different stages of the maturity of the ovary for a number of females from the three areas. The state of maturity has been divided into three categories; "Immature" indicates that the oviducal diverticula could not beoseen i n stained specimens, or were visible only as threads (Fig. IX-l); "Mature" indicates the ovary has developed oviducal diverticula (Fig. IX-2); "Ripe" indicates there are well developed oviducal diverticula and eggs (Fig. IX-3). The specimens examined were stained using carmalum (Mayer) and mounted i n Canada balsam. The data obtained are presented i n Table 22. It i s clear that for the B. C. specimens, the apparently three-segmented (Fig. IX-4) f i f t h leg was present more frequently on immature females and that the three to four-segmented (Fig. IX-5), or four-segmented (Fig. IX-6) f i f t h legs occurred with advanced maturity. There were no immature specimens 36 found in the samples from the North Atlantic and Southern California. The lengths of the three terminal bristles of the distal segment of the f i f t h legs of adult females appear to be related to the number of clearly demarcated segments of the leg. In the "three-segmented leg", they are almost the same length (Fig. IX-4), or the innermost one may be slightly lo longer (Fig. IX-5). In the "four-segmented leg", they decrease in length from.the inner margin towards the outer margin (Figs. IX-5, 6). The reason for these changes i s not understood. Possibly, the change in number of segments results from the division between the segments becom-ing more clearly differentiated as maturity advances. Alternatively, there may be additional moults in the mature specimens. If so, the changes in number of segments could occur at the moults. Whatever the cause of these changes, i t s effect is to make segmentation of the f i f t h limbs and the lengths of the bristles diagnostic features to be used with care. The length of furca compared with the length of the anal segment is variable among specimens from the populations examined from Indian Arm, North Atlantic, and Southern California. Table 23 shows the:.percentage of specimens in the population in which the furcae were longer, equal to, and shorter than the length of the anal segment. In a l l areas, the highest percentage of specimens have furcae longer than the anal segment. However, the Indian Arm form has the greatest percentage of longer furcae, followed by the Southern Californian form, and lastly, the North Atlantic form. The percentage of specimen with equal length of furca and anal segment is high-est in the North Atlantic form, intermediate in the Southern Californian form, and least in the Indian Arm form. Specimens in which the furcae were shorter than the anal segment were not found in the Indian Arm form, but 37 the North Atlantic form has a higher percentage than the Southern Califor-nian population. From these data i t would seem that there are real differences between the forms found i n the three areas i n the length of the furcae compared with the length of the anal segment, when treated at a population le v e l . However, there i s variation between specimens within a population such that, for individual specimens, or small numbers i n a sample, the dia-gnostic value of this feature would be doubtful. o The number of spines and setae on the fourth segment of the shorter f i f t h leg of the male (Fig. VIII-19d) has been stated to vary between species (Brodsky, 1950; Table 21). However, this does not appear to be true of the specimens examined i n the present study. A l l males from the three areas have a small seta and a bluntly pointed spine on this segment (Figs. IX-22, 23, 24). There appear to be slight differences between males of the three populations i n the proportional length of the shorter to the longer leg of the f i f t h pair. In Table 24, the shorter leg i s expressed as a percentage of the longer and the data are examined s t a t i s t i c a l l y . This examination indicates that the differences between any two of the three populations are not significant; i t also shows that the North Atlantic form resembles more closely the' Southern Californian form than either of these two resembles the Indian Arm form (Table 24). During the investigation a number of other characters, frequently used i n diagnosing the species, were used. These are the proportional lengths of segments of f i r s t antenna, metasome, and urosome. The pro-portional lengths of the segments of f i r s t antenna do not vary appreciably 38 for any of the specimens from any of the three areas. This is apparent in Fig. XI-7 (female's only). The same applies to the proportional lengths of the metasome and urosome (Figs. XI-5, 6) (female's only). These characters would not seem to be useful diagnosticallyyalthough they have frequently been used as such. Lengths of species reported in the literature may not be reliable since there has been confusion in identifying species and therefore i t is pos-.sible that in earlier records measurements given for one species may have included those for several. This is suggested by the large range of sizes in some of the entries in Table 25 where measurements given by a number of writers are listed. However, measurements of the specimens made from the three areas, Indian Arm, North Atlantic, and Southern California, in the present study, indicate there are size differences (Table 26). The Indian Arm specimens are approximately the same size as M. lucens, but larger than the Californian species. The shapes of the heads' of M. pacifica, and species from the three localities studied differ. The profile of the Indian Arm form is less convexly rounded when compared with Brodsky's M. Pacifica, but much more convexly rounded than the specimens from the North Atlantic and Southern California (Figs. IX-7, 8, 9). Setae situated on the distal corners of the seventeenth and eighteenth visible segments of the geniculated antenna of males differ for the three forms (Figs. VIII-7, 8). These setae are long in Indian Arm specimens (Fig. IX-19a) and short in the North Atlantic form (Fig. IX-20a), while the Southern Californian form (Fig. IX-2la) has setae of intermediate length. There are also differences between the specimens from the three 39 l o c a l i t i e s i n the length of an elongate process extending from the inner d i s t a l end of the eighteenth segment. In the Indian Arm form (Fig. IX-19b) i t i s longest and bluntly tipped; i n the North Atlantic form (Fig. IX-20b), i t tapers to a point and i s of intermediate length; while i n the Southern Californian form (Fig. IX-21b), i t i s shortest and bluntly pointed. The masticatory teeth on the mandible also show slight morphological differences. The Indian Arm specimens have blunt teeth (Figs. IX-10, 16) compared with the North Atlantic form's sharp teeth (Figs. IX-11, 17). The teeth i n the Southern Californian form are intermediate between these (Figs. IX-12, 18). The relative length of the setae on the geniculated segments and the teeth structure on the mandible appear to consistently di f f e r between specimens from the three areas. These may be regarded as useful diagnostic characters. Table 27 i s a comparative summary of the characteristics of the three populations from Indian Arm, North Atlantic, and Southern California, and some available information of M. pacifica. From the data presented, specimens of Metridia from Indian Arm are similar to M. lucens from the North Atlantic and the Southern Californian species i n the proportional lengths of segments of f i r s t antenna, metasome, and urosome, in the f i f t h legs of the females and the terminal bri s t l e s of the female's f i f t h legs, and i n the structure, variation i n and proportions of, the shorter to longer rami of the f i f t h legs of males. These characters have been previously used diagnostically, but as indicated already, i t would seem that they should be used vdth caution. Differences among these forms are apparent i n the shapes of the head profiles, the size and form of setae of the geniculate segment of the f i r s t antenna i n males, and i n the teeth 40 on the mandibles. Other differences between specimens from the several areas, possibly of a less reliable nature, are to be found i n the sizes, and i n the relative lengths of furcae and anal segment. I t would seem that there i s l i t t l e reason, despite the several similarities to confuse the identity of specimens from Indian Arm with the Californian species, or with M. lucens from the North Atlantic. Brodsky's (1950) data are sparse on M. pacifica, but the local speci-mens from Indian Arm seem to be similar to his description and i l l u s t r a t i o n . M. pacifica i s about the same size as the Indian Arm form; the head-shape i s also convexly rounded. I t i s possible the Indian Arm form may be M. pacifica, but direct comparison with specimens of this species i s desirable before f i n a l l y identifying the Indian Arm species. Therefore, the identity i s l e f t open at present. IV. LIFE HISTORY AND CYCLES Life histories.of calanoid copepods related to the present study-have been detailed by Lebour (1916) on Calanus finmarchicus (naupliar and copepodid stages), Campbell (1934a) on Euchaeta japonica (= Pareu-^-chaeta japonica) (naupliar and copepodid stages), and Gibbons (1938) on Metridia lucens (nauplius only). In the present study, two species have been selected, namely Calanus  sp. and Gaetanus armiger. The distributions of l i f e history stages of these species, which as adults l i v e at different depths and in different relation to temperature, salinity, and oxygen have been compared. Calanus sp. represents a species which lives predominantly i n the upper levels, and Gaetanus armiger almost only i n the deeper water i n Indian Arm'. Brief descriptions of the copepodid stages of these two species, together with a more detailed study of the appendages of G. armiger, have been made and are presented below. Some ecological relationships are discussed i n a later section. The l i f e cycle of Calanus finmarchicus i s probably the best known among copepods. It has been investigated frequently (Russell, 1928; Ruud, 1929; Runnstrdm, 1932; Marshall, Nicholls, and Orr, 1934; Sdmme, 1934; Wiborg, 1934, 1954; Fish, 1936; Wimpenny, 1937; Ussing, 1938; and Jaschnov, 1939). Most of these have been i n the North Atlantic (Marshall and Orr, 1957). In the North Pacific, this kind of work, comparatively, i s neglected. Of the two species being discussed, the l i f e cycle of G. armiger has not been studied previously. 42 A study of the seasonal fluctuations of the copepodid stages of Calanus sp. and Gaetanus armiger may provide useful ecological informa-tion concerning the l i f e cycles of these two nost abundant species inhabit-ing different ecological niches. In addition, knowledge of the distribu-tion of the earlier stages of animals in relation to oceanographic condi-tions may provide a means from an ecological point of view of studying water movement in a small area such as in a fjord. An estimation of.the abundance of each copepodid stage was made as the number of specimens per cubic metre of water filtered. The largest count of specimens of each stage was chosen from a l l of the samples, collected during one complete day and night collection, from a l l stations and depths . (Fig. 1-2). The number of specimens for each stage thus obtained provides an indication of the maximum number of specimens present in the inlet during the cruise and has been used to illustrate gross seasonal fluctuation of the population of each stage. Life history stages of Calanus sp. A l l six copepodid stages of Calanus sp. were found in Indian Arm, and the following account concerns these. Naupliar stages were infrequently found due to the incomplete collection by the larger mesh aperture (0.4mm) used, and were not studied. Lebout (1916) has fully described the naupliar and copepodid stages of C.1finmarchicus. Marshall and Orr (1955) also tabulated the segmentation and setation of appendages of a l l stages of Calanus finmarchicus. The copepodids of Calanus sp. from Indian Arm do not appear to differ, except in details, from C. finmarchicus. These details are not specified in the present study. Descriptions given below 43 are sufficient to identify the stages in B. C. waters. Copepodid I can be identified from its body length and the presence of relatively long plumose setae on the penultimate and antepenultimate segments of the fi r s t antennae. These setae are absent in the same stage of the other species studied. The total body length is between 0.77mm and 1.03mm (12 measurements). There are four segments in the metasome and two segments in the urosome. The rostrum is indicated by a pointed, rudi-mentary process, Rostral filaments cannot be seen. The f i r s t antenna has ten segments and extends to the distal end of the furca. There are two pairs of swimming legs and a pair of rudimentary third legs. The second copepodid stage is between 1.01mm and 1.42mm (15 measure-ments) in length, has five segments to the metasome, and two segments to the urosome. The rostral filaments are weH developed. The fi r s t antenna has fifteen segments and extends beyond the furca by about two segments. There are three pairs of swimming legs and a pair of rudimentary fourth legs on the metasome. The third copepodid stage is from 1.41mm to 1.93™ (14 measurements) in total length. It has six segments to the metasome and two segments to the urosome. The f i r s t antenna has twenty-three segments and extends beyond the distal end of furca by about two segments. There are four pairs of developed swimming legs and a pair of rudimentary f i f t h legs. The Copepodid IV is from 1.91mm to 2.56mm (10 measurements) in total length, with a six-segmented metasome and three-segmented urosome. The fir s t antenna has twenty-four segments, and extends beyond the distal end of furca by at least two segments. There are five pairs of swimming legs. 44 The f i f t h copepodid stage is from 2.37mm to 3.42mm (20 measurements) in total length, with a six-segmented metasome and four-segmented urosome. Head shapes are distinguishable between the large and small forms, but • not sexes. The f i r s t antenna has twenty-five segments and extends beyond the distal end of furca by about two segments. In some specimens the f i r s t antennae .^exceed;'the distal".end of the furcae by more than two segments; these are thought to be the immature males. There are five pairs of swimming legs, each leg with two-segmented endo-:ahd exo-podites. The adult stage of Calanus sp. has been described in the section on systematic?. Life cycle of Calanus sp. Calanus sp. includes two size groups, as discussed i n the systematic section; since they could not be separated in the juvenile stages, the present study combines both size groups, at each stage, as a group. The seasonal fluctuation of each copepodid stage of the Calanus population has been shown in the histogram (Fig. XII-1). The males appeared in low numbers in February, 1961; numbers increased only slightlj- up to June, but there was a considerable increase in August. By September, 1961, numbers were again at a lo\i level. It would seem from the I960 data that such low numbers would persist from September through the winter. The numbers of the females were higher than the males a l l the time, except in August, 1961. Numbers increased from Feb-ruary; as with males, but reached their maximum in September, 1961, and to judge from I960 data, decreased rapidly to comparatively low numbers during the winter. 45 The f i r s t appearance of copepodid I was i n A p r i l , but i t was accom-panied by higher numbers of the later stages, copepodids I I , III, and IV. Such a combination of stages suggests that breeding had commenced earlier than A p r i l . Copulation probably commenced with the appearance of mature males earlier i n the year (February). The number of both males and females was low, however, and any such copepodid stages would also have been i n low number. . A second breeding season probably occurred between June and August. The very high numbers of stage I i n August suggest this. Relatively high numbers of later stages, I I , III, IV, and V, were also present i n August. As with the cycle i n A p r i l this suggests that breeding may have extended for a long period. The l i f e history cycles were studied from samples collected usually at two-month intervals; however, there were no collections for July to September, I960, and May and July, 1961. These incomplete series have made interpretations d i f f i c u l t . I t i s possible, nevertheless, to make a general comparison with data on l i f e cycles from Loch Striven Scotland, detailed by Marshall, Nicholls, and Orr (1934). Calanus sp. from Indian Arm appears to have a similar cycle to the Loch Striven Calanus i n that there were two peaks during spring and summer seasons. Although data from Indian Arm did not show the f i r s t maximum of the adult stage clearly, i f the two-year record i s combined, the f i r s t maximum can be said to have occurred before May, I960, and the second i n September, 1961. 46 Life history stages of Gaetanus armiger. Living Gaetanus armiger can be kept in vials, in the original sea water in which the animals were collected, for more than two months in a cool-room, at 10°C. Eggs can be collected from freshly caught, ripe females (Fig. XXII-l), after they have been kept in a vial for from two to four days. The eggs (Fig. XXII-2) develop in the vial up to Nauplius I (Figs. XXII-3, 4). After two to four days the females seldom lay eggs. Although eggs may be present in their oviducts, they appear to be resorbed by the female after this period. The egg is spherical (Fig. XXII-2) with o i l droplets inside, and a transparent membrane outside. The diameter of the egg proper and of the egg plus membrane have been measured (Table 28). The egg proper ranges from 0.30mm to 0.35mm (7 measurements), but i f the outer membrane is included, the diameter ranges from 0.53mm to 0.73mm. From this i t is apparent that the thickness of the transparent membrane is quite variable. The nauplius I (Fig. XXII-3, 4) is about 0.36mm in length with o i l droplets inside. It is oval in shape with three pairs of appendages, the fi r s t antennae, the second antennae, and the mandibles. It is grey in color, within a two-layered membrane when i t i s just formed from the egg (Fig. XXII-2). There are usually another five naupliar stages after nauplius I before i t moults into copepodid I. These stages are not des-cribed in the present study. Specimens vrere incompletely collected, because the mesh used (No. 2) was too coarse. Complete diagrams of the copepodid stages and their appendages have 47 been made (Plates IV, V, VI), and a brief comparison.of the segments of the appendages of each stage, as well as sexes, i s tabulated (Table 29). Copepodid I (Fig. IV-l) i s about 0.85mm i n length with three segments i n the metasome and two segments i n the urosome. It i s grey i n color and has o i l droplets contained i n the metasome. There i s no spine on the front of the head, and no rostrum. It i s distinguishable from the other species by i t s f i r s t antenna, the maxilliped, swimming legs, and the color and body size. The f i r s t antenna (Fig. IV-13) i s ten-segmented with very long setae on the d i s t a l ends of the third, sixth, eighth, and ninth segments. The shape of the maxilliped (Fig. V-29) i s similar i n appearance to that of the adult, but has only four segments. There are two pairs of swimming legs (Figs. VI-1, 7) and a pair of rudimentary third legs (Fig. IV- l ) . The second leg (Fig. VI-7) has a serrated spine on the d i s t a l end of the exopodite; this i s not found i n other species at the same stage, except Pareuchaeta .japonica which i s about 1.2mm i n length (Campbell, 1934a), and therefore much bigger than copepodid I i n Gaetanus  armiger. Copepodid II (Fig. IV-2) i s about 1.15mm i n length with four segments i n the metasome and two segments i n the urosome. A long sharp spine, ex-tending forwards i n front of the head, i s a diagnostically distinctive character. The rostrum has not developed. The mouthparts (Figs. V-2, 9, 16, 23, 30), have advanced i n their development, e.g. there are five seg-ments on the maxilliped (Fig. V-30)(cf. Figs. V - l , 8, 15, 22, 29). There are three pairs of swimraing legs (Figs. VI-2, 8, 13) and a pair of rudi-mentary fourth legs (Fig. IV-2). The f i r s t antennae are seventeen-segmented (Fig. IV-14) and the number of larger setae have increased to f i v e . 48 The third copepodid stage (Fig. IV-3) i s about 1.55mm i n length and has four metasomal segments and two urosomal segments. The frontal spine tends to curve ventrally and there are indications that a rostrum i s pre-sent. The f i r s t antennae (Fig. IV-15) have twenty-two segments on each. There are four pairs of swimming legs (Figs. VI-3, 9, 14, 18). Six seg-ments are vi s i b l e on the'maxilliped'(Fig'." .:.V?3l). From the fourth copepodid stage (Figs. IV-4, 7) on, the sexes can be distinguished. The body lengths are similar i n "male" and "female" about 2.00mm i n t o t a l . Appendages do not d i f f e r , except for the addition of the f i f t h swimming legs i n males (Fig. VI-22). No additional segment i s added to the metasome i n this stage, but a spine on the postero-lateral corner of the last segment i s present at this and i n subsequent stages. There are three abdominal segments. The f i r s t antenna (Fig. IV-16) has twenty-four segments. The frontal spine i s more strongly curved ventrally than i n the third copepodid stage. The f i f t h legs of the male (Figs. IV-7, VI-22) are symmetrical, each leg with unsegmented endopodite and exopo-dite; the endopodite i s about one-half the length of the exopodite. The f i f t h copepodid stage (Fig. 1T-5, 8) has several differences over the fourth stage. The body length i s about 2.70mm i n females, 2.65mm in males. The metasome and urosome' are both four-segmented. The frontal spine l i e s almost parallel to the head contour. The rostrum i s well de-veloped. The maxilliped (Fig. V-33) Is seven-segmented. The f i r s t an-tenna (Fig. IV-17) has•twenty-four segments. There are four pairs of swimming legs i n the female (Figs. IV-5, VI-5, 11, 16, 20), five pairs i n the male (Figs. IV-8, VI-23). The four anterior pairs of swimming legs of 49 males are similar to those of females. The f i f t h pair are symmetrical (Fig. VT-23) with unsegmented endopodite and exopodite, the exopodite i s about four times longer than the endopodite. The d i s t a l end of the exopodite i s sharply pointed. The adult stage has been described i n the section on systematics. Life Cycle of Gaetanus armiger. Gaetanus armiger shows a different pattern of seasonal distribution (Fig. XII-2) from Calanus sp. (Fig. XII-l). The stage V male was present much of the time; specimens occurred i n high numbers i n October and Dec-ember, I960, and i n August and .September, 1961. Adult males, however, were common for a few months. They were present i n appreciable numbers only i n October and December, I960, and February, 1961; very low numbers occurred also i n A p r i l , 1961. Adult females were found commonly through-out the year, but were most abundant i n April,.1961 and June, I960, i . e . i n spring and early summer. Copulation probably occurred i n winter, when the males were abundant. A few stage I and II copepodites were present i n February which suggests breeding had commenced earlier, perhaps i n January. Peak breeding, to judge from the numbers of copepodid I, was reached i n A p r i l to June i n 1961; :-. '. i n May and June of I960, numbers of copepodid I were very low, "and probably the peak was over or not sampled. Subsequent to June, 1961, numbers of copepodid I decreased (and none was collected i n October or December, I960). 50 Peak numbers of stages subsequent t o stage I occurred, i n prog r e s s -i v e l y l a t e r months during the year. The sequence about c o i n c i d e s w i t h the two-monthly sampling i n t e r v a l . I n I960, stage I I appeared i n h i g h numbers i n May; t h i s suggests an e a r l i e r breeding p e r i o d , p o s s i b l y i n A p r i l , as occurred i n 1961 (but few stage I were c o l l e c t e d i n May, I960). By June, I960, stage I I I was present i n high numbers. The peak numbers of stage IV was probably missed i n the unsampled p e r i o d between June and October, I960. By October, however, stage V and a d u l t s were dominant i n the catches. I n 1961, the cycle was s i m i l a r ; a d d i t i o n a l l y the peak occurrence of stage I i s shown t o have been i n A p r i l . I t appears, t h e r e f o r e , t h a t here was a s i n g l e c y c l e of breeding which was prolonged, but showed a maximum of a c t i v i t y i n s p r i n g . This c o n t r a s t s w i t h Calanus, i n which i n d i c a t i o n s of two c y c l e s were apparent. 51 V. OCEANOGRAPHIC CONDITIONS Indian Arm, or North Arm, a branch of Burrard Inlet (Vancouver Harbour), is located between 49°18'N and 49°29'N Lat., and 122°51'W and 122°57'W Long. (Fig. I - l ) . It has a total length of twenty-two kilo-metres and an average width of slightly more than one kilometre. A deep basin occupies three-fourths of i t s length. The greatest depth is about two hundred metres at Stations 6 and 9 (Fig. 1-2). The basin shoals rather rapidly in the south to a s i l l about twenty-six metres deep (Station 23, Fig. 1-2), and in the north gradually to the estuary of the Indian, or Mesliloet, River up-inlet from Station 2 (Fig. 1-2). The inlet i s surrounded by mountains up to 1400 metres high on the east and west sides (Gilmartin, I960). Oceanographic conditions have been previously surveyed by Gilmartin (i960) and McHardy (1961). The present investigation of temperature, salinity, and oxygen extends their results to September, 1961. Data are presented for approximately two-month intervals. -Temperature, salinity, and oxygen have been plotted as isopleths in the longitudinal profile of the inlet. The maximum and minimum values of each factor Recorded in the period from May, I960, to September, 1961, and the time and place at which these records were taken, are summarized in Table 30. This table indicates there i s a wide range of temperature at the surface during the year. The values for salinity and oxygen (Table 30) also show the extreme, vertical range obtained during the year. It is clear that the organisms in the shallower depths may have to \-ri.thstand large changes. 52 In general, as with many other B. C. inlets, temperature and oxygen are decreasing, but salinity is increasing downwards. Horizontally at the surface, salinity increases towards the mouth. This is typical of B. C. inlets (Pickard, 1961). Temperature Fig. XIII-1 demonstrates that temperature fluctuations occurred in the upper levels, above 100m or 120m. In June, August, and September, 1961, the temperature was generally higher at a l l depths than in the winter and spring seasons, but there s t i l l was a relatively greater range of variation in the upper than in the deeper,levels. From December, I960, to April, 1961, there was a subsurface warm tongue which extended down inlet from the northern end. This tongue was delineated by the 8.5°C isotherm in December, I960 (Fig. XIII-la). Its upper limits ; were just underneath the surface at Station 2 and a few metres deep at Sta-tion 12; i t s lower limit reached about 50m deep at Station 12 and about 90m deep at Station 2 in January and February, 1961 (Figs X l l l - l b , l c ) . This tongue probably is warm water of the previous summer which has been depress-ed by the winter cooled surface water of lower temperature, represented by the 8.0°C isotherm. In March, 1961 (Fig. Xlll-ld), the tongue was separated into two parts: the upper part was between the depths of 10m and 20m at Station 2; the lower part extended from Station 2 to Station 6 and was between 60m and 80m deep. This may have resulted from an up-inlet intrusion centered at about the 50m level. In April, 1961 (Fig. XIII-le) the deeper tongue (lower part)'of 8.5CC water had retreated to Station 2, at the same depth of 60m to 80m as in March. The upper tongue, however, may have 53 extended down inlet covering the whole inlet with water of 8.5°Cj or this water of 8.5°C may have been the result of. the seasonal warming. From June to September, 1961 (Figs. X l l l - l f , lg, lh), the temperature in the upper levels increased month by month. By June, 1961, the tongue demarcated., by the 8.5°C isotherm had disappeared and water of higher temperature extended to the upper levels and covered the whole inlet. In June and August, there was no unusual change to suggest an influence extending into the inlet from outside. In September, 1961, a higher temperature tongue demarcated by the 11.0°C isotherm extended from the southern part northwards at levels above 60m and occupied the length of the inlet. The deep water may be arbitrarily considered as occurring below 120m in the basin, with a temperature of 8.0°C, or lower. It was consistently present in winter; and spring, from December, 1960^to April, 1961 (Figs. XIII-la, lb, l c , Id, le). As the deep water warmed in. summer and f a l l , from June to September, 1961 (Figs. XIII- If, lg, lh), the 8.0°C isotherm deepen-ed. This occurred fi r s t in June; subsequently, in August and September, i t disappeared. However, variation of temperature in the basin near the bottom was only about 0.5°C, consisting of an increase from 7.73° to 8.25°C, over the period December, I960, to September, 1961. Salinity . Salinity (Fig. XIII-2) shows a wide variation, as with temperature, i n the levels above 100m to 120m. The salinity was low at and near the surface, especially between January and February (Figs. XIII-2b, 2c), and April to August (Figs. XIII-2e, 2f, 2g). In general, the salinity decreased from December, I960, to March, 1961, and increased from April t i l l August in the 54 deeper levels. After August, i t decreased again until late f a l l or early winter,, to values approaching those present in December, I960. The 26.75 isohaline has been arbitrarily selected to indicate changes of distribution of salinity affecting shallow and deep waters. This iso-haline demarcated the upper levels at about 60m in December, I960 (Fig. XIII-2a); i t deepened to between 90m and 120m in January, 1961 (Fig. XIII-2b); at the same time there appeared to be a descending tongue of low salinity water between Stations 6 and 9. In February, and thereafter to August (Figs. XIII-2c, 2d, 2e, 2f, 2g) i t fluctuated around the 90m level. In September (Eig. XIII-2h), i t descended below 120m. In waters at levels below 120m, the salinity ranged between 26.75^° to 27.13 °fa , a variation of about 0.4 i°° . Dissolved Oxygen The distribution of the non-conservative property, dissolved oxygen (Fig. XIII-3), generally corresponded with temperature. The isopleth of 3.5ml/l, as with salinity, has been arbitrarily selected to distinguish the distribution of oxygen between shallow and deep waters. It varied in depth between 20m and 120m. This isopleth reached i t s deepest level, 120m, in January and February (Figs. XIII-3b, 3c). During these months a higher oxygen tongue was formed between 60m and 100m at Station 12, i t may have extended northwards to Station 9 i n February. In March, 1961, a tongue . • appeared to reach Station 2, at depths between 30m and 60m (Fig. XIII-3d). In April (Fig. XIII-3e), the isopleths were almost parallel with the sur-face except towards the mouth where there were slightly higher concentra-tions. A high oxygen tongue with values of S.Cml/1 was detected at Station 2, 6, and 9 in the levels about 20m in June, 1961 (Fig. XIII-3f). The 3.5ml/l isopleth formed a down-inlet tongue again in September, 1961 (Fig. XUI-3h) similar to the distribution in December, I960 (Fig. XIII-3a). In addition, this tongue overlaid and may have been caused by, a deeper tongue of high oxygen water which extended up-inlet to Station 6. Oxygen in the deep water below 120m ranged from 1.75ml/l to 2.5ml/l. The variation was 0.75ml/l» Discussion of Oceanographic Conditions Indian Arm belongs to the type of inlet with medium runoff (Pickard, 1961). A two-layer system was indicated by Gilmartin (i960). Freshwater drains into the inlet from the Indian River at the northern end of the inlet and from perpheral streams. It spreads at the surface and flows southwards mixing with the underlying water and carrying some of i t out of the inlet. A compensatory replacement of this water, plus intruded water due to tidal movement, enters the inlet beneath the outgoing low salinity surface water. These movements describe the general nature of the circula-tion in the inlet. The water in the basin has entered as the combined result of effects of freshwater runoff, flushing and intrusion of relatively high salinity water. Water movements indicated by the three factors, temperature, salinity, and oxygen, suggest that inllow of outside water did affect environmental conditions during the period from December, I960, to September, 1961. But this affect was more frequent at the shallow than at the deep levels. The salinity distribution suggests that mixing and dilution processes 56 occurred during December, I960 and January, 1961. During this period, the salinity of the deep water decreased, shown by the 27.0 ^  isohaline being deepened until i t was located near the bottom. In March, temperature and oxygen suggested a considerable inflow of water of lower temperature, and higher oxygen at the levels between 90m and the surface. During April, June and August (Figs. XUI-1, 2, 3: e, f, g), there were no indications of strong inflows of water of salinity greater than 26.25 °l°o into the inlet. However, inflow must have occurred as there was ' very low salinity at and near the surface which would be flowing out from the inlet and would have to be replaced. Possibly the increased salinity in deep waters, higher than 27.0 $0, was the result of a continuing slow replacement of the outflowing surface water by higher salinity water. Another inflow i s suggested in September. Both isotherms and oxygen isopleths showed this (Figs. XIII-1, 3: b). The isohalines slope (Fig. XIII-2h) downward towards the head of the inlet and i t could be suggested that this slope results from water of salinity of 26.25 c/°° to 26.75 °M flowing along the isohalines at intermediate depths into the basin. Such a flow could also account for the deepening of the 8.25°C isotherm from 90m i n August to 120m i n September and deepening of the 26.75 f°° isohaline over approximately the same range of depth. From this brief survey of the physical oceanography, i t appears that during the period of December, i960 to September, 1961, there were relatively stable conditions in Indian Arm, more especially in waters below about 100m. In the subsurface waters above 100m, there were fairly clear indications of inflow between about 30m and 60m, in March and September, 1961; possibly one occurred in December, I960, and January; in February, 1961, some 57 instability is indicated about Stations 6 and 9, but this was either a transitory feature or due to surface water contamination of a deeper water sample. It was not observed twenty-four hours later. No strong evidence of inflow into the bottom of the basin was available, but changes in salinity suggest there was a continuing inflow of small quantities of relatively higher salinity water commencing about April and ending about June, 1961. These results are consistent with those results from a survey conducted over three years by,Gilaaartin (i960). He showed that the general circula-tion of Indian Arm was explained with reference to low salinity surface water that flowed out of the inlet being replaced by outside higher salinity water flowing in at deeper levels. In the present study, i t i s more conve-nient to divide the water in the inlet arbitrarily into three instead of two levels. The surface water varies widely in temperature, salinity, and dissolved oxygen, down to a depth not greater than 10m. Below this is a mixture of surface and deep water. This is called intermediate water. It had relatively narrower ranges of temperature, salinity, and oxygen than the surface water. The depth range of this water shown in Figs. XEII-1, 2, 3 is between 10m and 100m or 120m levels. A deep water with narrow varia-tion of the three properties is located below the 100m to 120m depth levels. This water i s relatively stable compared with the waters above. 58 VI. TEMPERATURE* SALINITY, AND OXYGEN IN RELATION TO COPEPODS In recent years, a technique has been developed i n which occurrences of zooplanktonic organisms are shown in direct relation to the tempera-ture and salinity of the water at the time and place the organisms were captured. The method is to enter the presence or absence of selected species (by means of symbols) in the intercept of the temperature plotted against the salinity existing at each of the positions at which a plankton sample was collected. In this manner, observations of temperature, salinity and the concurrent occurrences of species are shown. If species are more closely related in their occurrences to some particular range of conditions in the water properties, in this case temperature and salinity, the technique will demonstrate this (Bary, 1959). In the present study, temperature, salinity, and plankton (Calanus sp. and Gaetanus armiger) are combined in diagrams (the T-S-P diagrams, Figs. XV-1, 2). Additional diagrams are proposed. In these, oxygen-salinity-plankton (O-S-P, Figs. XVI-1, 2) and oxygen-temperature-plankton (O-T-P, Figs. XVII-1, 2) are plotted using the same principle as that used in the T-S-P diagram. In each of these diagrams, a l l occurrences of a l l copepodid stages of the two selected species for the period surveyed are plotted; absences are indicated from a sample by the absence of symbols for the stages. The largest dot at the top in the circle (Fig. XV-1, 2) represents the adult female, the second largest to its left represents the adult male, and the next, copepodite V, and so on; the smallest represents copepodite I, which is located to the right side of the largest representing the adult female. The treatment outlined does not permit a study of seasonal occurrences 59 in relation to temperature, salinity, and oxygen. However, i t permits observations of the overall similarities and differences to be made between the life-history stages of one species and between stages of more than one species. To assist i n a ready interpretation of the diagrams, simple block diagrams have been constructed. These show by means of rectangles the maximal and minimal values (Table 31) of each temperature and salinity (Fig. XIV-l), oxygen and salinity (Fig. XIV-2), and oxygen and temperature (Fig. XIV-3) inhabited by each copepodid stage of Calanus sp. and Gaetanus  armiger. In general, the properties in Indian Arm are distributed such that temperature decreases and salinity increases downward to the deeper waters. As the distribution of properties is relatively consistent over the period plotted points tend to group together. In the T-S-P diagrams, this means that points plotted for the deep, high-salinity, low-temperature water occur towards the lower right side of the diagrams (Figs. XV-1, 2). On the other hand, in sub-surface and surface waters there are wide ranges of dilution, which spreads .the point towards the left on.the diagrams; and temperatures are low in \iri.nter and high in summer which spread the points vertically on the diagram. Therefore points from sub-surface and surface waters are scattered. Points from waters of intermediate depths f a l l at higher temperatures than those from deep waters; but these waters do not vary in temperatures or salinities to same amount as those from shallower waters. Oxygen in general also decreases in concentration downwards to fairly stable conditions in the deeper waters in which the concentration varied only slightly in the period investigated. However, i t varied widely i n the 60 upper waters. Therefore in the 0-S-P (Figs. XVI-1, 2), and 0-T-P (Figs. XVII-1, 2) diagrams, the oxygen relation of the deep water i s shown in a group of points in which high salinity is related to low oxygen, or low temperature i s related to low oxygen. Surface or sub-surface waters are v variable in oxygen content and the points representing them are scattered. Temperature-Salinity-Plankton Isopleths of (equal density) have been entered on the T-S-P diagrams (Figs. XV-1, 2) showing an indication of depth. In the inlets, in general, density is determined by salinity rather than temperature. Therefore, a t increases with increasing salinity, i.e. as the deep water i s reached. The arbitrary separation of the water into three parts in the inlet, suggested i n the previous section, can be indicated from these diagrams. The surface water may be represented by the points laying on and to the left of o^ equals to, or less than 18. The intermediate water i s represented by a group of points plotted between the isopleths of 18 and 20 or 20.5 O f The deep water i s indicated by the points plotted around the isopleth of 21 o^. Calanus sp. From the T-S-P diagram (Fig. XV-1), i t i s clear that Calanus can with-stand low salinity and a broad temperature range (Table 31, Fig. XIV-1). This applies especially to the young stages and to adult females. On the other hand, a l l stages occurred in water of higher salinity and lower temperature sampled from the deeper levels; but young stages (I to III) were less common than later stages in this water. In the general block-diagram (Fig. XIV-l) adult females of Calanus are 61 shown to have been present throughout the range of conditions available, although the extreme low s a l i n i t y i s represented by only one sample; occur-rances at high temperatures are better documented by two or three samples. This range for adult females contrasts strongly with the requirements of adult males which occurred only at low temperatures and high s a l i n i t i e s . Adult males were common i n deep water and less common i n intermediate water, but were not found i n surface water (Fig. XV-l). Juveniles, stages I to V, appear to have occurred i n ranges of conditions intermediate between those of the adult males and females. Stages I to IV are shorn to have similar requirements. They did not occur i n water of the lowest s a l i n i t y and temperature, but as only one sample was collected from water with these preperties (10°C and 10 °/ooi Fig. XV-l) specimens may have been missed. I t i s probable that stages I to IV differed inappreciably i n their occurrences from the adult female. Stage V was collected from water of the same temperature range, but of much higher sa l i n i t i e s than the females and other juvenile stages. I t occurred i n conditions intermediate between those of the females and males. The most noticeable fact that the T-S-P diagrams indicate, for Calanus, i s the real difference between the ranges of temperature and s a l i n i t y occupied by adult females, males, and stage V. From the data available juvenile stages I to IV have only slight differences, i f any, i n their temperature requirements from adult females. In general, these stages of Calanus may be expected occurring throughout the waters of Indian Arm. Stage V was present i n more restricted conditions, avoiding low s a l i n i t y water; adult males appear to inhabit only the waters of low temperature and high s a l i n i t y (deep water) and they sometimes occurred i n intermediate water, of . sl i g h t l y higher temperature. 62 Gaetanus armiger Gaetanus armiger i s shown i n the T-S-P diagram;,(Fig. XV-2) as restricted to the deep water, represented by the points grouped to the right side of the isopleth of 20. Adult females were found i n the lower edge of the intermediate water ( i . e . i n the transition zone between the intermediate and deep water) and i n the deep water. Adult males were collected only i n water i n which the sa l i n i t y was about 27% and the temperature about 7»5°C to 8.5°C. Females therefore occupied a relatively wide range of conditions compared with males. Stage V occupied similar conditions to the adult females. Stage IV may be found occasionally i n the upper edge of the deep water, at temperatures not higher than 9.5°C. Both stages III and II occurred within the sal i n i t y range of 26.0 % to 27.0 %, but stage III may occur within the temperature range between 7.5°C and 9.0°C and stage II between 8.0° to 9.©°C. Stage I was found i n the water of temperature from 8.0° to 8.5°C, and salini t y from 26.5% to 27.0%. In general, the adults and copepodid stages of Gaetanus armiger were confined i n water with properties of deep water. In Fig. XIV, the small differences i n temperature and sa l i n i t y requirements of the adults and stage I to V appear to form a pattern: females and stage V appear to possess the widest tolerance to conditions; tolerances i n stages IV to I appear to become less as indicated by the progressive restriction i n the range of conditions inhabited. Males occupied the most restricted range, at the lowest temperatures and highest s a l i n i t i e s . These general conclusions are based on a small amount of data and need further study. Nevertheless, they suggest interesting differences between one stage and another which w i l l be discussed later (see Discussion). 63 Gxygen-Salirri,ty;-Plankton The G-S-P diagrams (Figs. XVI-1, 2) show wide salinity variations at high oxygen concentrations. Samples in which oxygen was higher than 5.5ml/l, may interpreted as representing surface water. On the other hand, the samples with oxygen less than 3.5ml/l are found to have salinities be-tween 26.5 and 27.0 °/oo'} these are. representative of deep water. In Between these two tiraters, intermediate or mixing water i s located in the diagrams. This division is not as distinct" as shown in the T-S-P diagrams of the previous section. Calanus sp. From the simple block diagram (Fig. XIV-2), Calanus females are seen to occupy a wide range of oxygen concentrations as well as salinities. As in the T-S-P diagram (Fig. XIV-l), males are restricted to narrower oxygen and salinity ranges than the females; stage V again occurred over an intermediate range between the adult females and males. Stages I to IV did not show differences towards salinity, as was mentioned in the discussion of the T-S-P diagram, but they appear to require high oxygen concentrations especially in the younger stages I and II. There is a pro-gressive decrease in oxygen requirements shown by the later stages III, IV, and V. There appear to be no differences in oxygen and salinity between stages I and II in the O-S-P diagram (Fig. XVI-l). From this, the earlier stages I to IV would appear to have been more commonly distributed in the surface and subsurface intermediate mixing waters of high oxygen. Females were found from the surface high oxygen water 64 occasionally, but much more frequently in waters with intermediate and low oxygen. The f i f t h stage showed almost the same requirements as the adult female. In adult males the requirements were for lower oxygen values (2.0 to 5.5ml/l). Gaetanus armiger In general, the copepodid stages of Gaetanus in relation to oxygen and salinity did not differ greatly from each other. Only very slight differences in the ranges inhabited exist between the successive stages when compared with Calanus. This is shown in both the simple block 0-S-P (Fig. XIV-2), and 0-S-P (Fig. XVT-2) diagrams. However, there are differences which are relatively large when compared with the total range of oxygen concentrations occupied by Gaetanus. The adult females and stage V occurred in similar properties of oxygen and salinity, from 1.5 to 5.0ml/l of oxygen, and from 25.5 to 27.0 % of salinity. Adult males occurred over a more restricted oxygen range, between 1.5 and 3.5ml/l at a salinity approximating 27.0% (as noted in the T-S-P diagrams, Figs XIV-1, XV-2). Stage IV has the same salinity range as stage V, but the range of oxygen falls between 2.0 and 4.5ml/l. Stages II and III were found in similar oxygen and salinity ranges, falling between 2.0 and 4.5ml/l, and 26.0 and 27.0%. The f i r s t copepodid stage was collected from water with an oxygen range of 2.0 to 4.0ml/l, and salinity range of 26.5 to 27.0%. From the above analysis, Gaetanus adult females and f i f t h copepodid stage were commonly distributed over a relatively wide range of oxygen. 65 This correlates with the intermediate and deep waters. The males were collected only at the lowest oxygens in deep high salinity water. The-.", earlier stages., II, III, and IV were found in similar ranges of oxygen concentrations which reached higher values than for stage I. The salinity ranges were wider for stages II, III, and IV than for stage I which indicates that stage I inhabited deeper water than the others. Qxygen-Tempe rature-Plankton Both temperature and oxygen have been shown to decrease downwards (Figs. XIII- 1, 3)« At the surface, temperature varied between high and low valuesj at the intermediate depths, intermediate values were recorded. Lowest oxygen concentrations and temperatures were recorded i n the deep waters. Thus the distribution of the points shown in Figs. XVII-1, 2 can be separated into three groups corresponding with the three water types discussed in connection with T-S-P, and O-S-P diagrams. The surface water i s shown by the scatterred points above oxygen values of 5-5ml/l and between temperatures of 6.0° and 14.5°C; the deep water i s that below 3.5mlA over the temperature range of 7.0° to 11.0oC; the intermediate water has an oxygen range of 3.5 to 5.5ml/l. As these factors, oxygen and temperature, have been discussed separately in relation to salinity above, they are not treated further here. However, copepodid and adult stages of the two species are shown by the 0-T-P diagrams to have the same distinctive distributions as was shown previously, (Figs. XIV- 3, XVII-1, 2). 66 VII. DISTRIBUTION OF COPEPODS • :- The distribution of each copepodid stage of Calanus sp. and Gaetanus armiger.in Indian Arm, B. C, during the months of December, I960, February, April, June, August, and September, 1961, has been plotted in the vertical longitudinal profile of the inlet, (Figs. XVIII, XIX, XX, XXI)'. These distributions can be compared with the distribution of temperature, salinity, and dissolved oxygen (Figs. XIII-1, 2, 3 ) . The plankton samples examined were collected immediately after the water samples were collected and temperature observations made. The concentrations of organisms are illustrated in the longitudinal profile of the inlet as the number of individuals collected per cubic metre of water filtered. Distribution of Calanus sp. In general, Calanus seems to inhabit principally the upper and inter-mediate levels (Figs. XVIII; XIX-1, 2, 3 ) . Adult stages seldom were found near the bottom; mostly they were concentrated at depths between 30m to 90m below the surface. The males appeared to live at deeper levels compared with the females during corresponding periods. (Figs. XVIII-1, 2 ) . Copepodid stage V occupied a l l depths except near the surface. On a few occasions high numbers were found near the bottom (Figs. XVIII-3). A concentration was found at depths about 30m to 50nr in the southern part of the inlet in April.(Fig. XVIII-3c) and August, 1961 (Fig. XVIII-3e); in June (Fig. XVIII-3d) and September, 1961 (Fig. XVIII-3f), i t was in the deep water. Concurrently, there were zones in which few or no organisms were present in intermediate depths at Station 6 in April, June, and August, 1961 (Figs. XVIII-3c, 3d, 3e); this feature may be related to water movements. 67 Copepodid IV was found mostly above the 120m level, and concentrated at about 50m below the surface. It was distributed in a horizontal zone except in June, 1961, usually in the southern part of the inlet at Stations 9, 12, and 15 (Figs. XVIII-4). Copepodid III was more often found in the upper 100m. In April and September, 1961, i t was concentrated in the southern part, between Stations 15 and 23; in June and August (Figs. XlX-ld, le), i t extended downrdnlet from Station 2 toxvards the mouth; in September, the chief concentration centre was in mid-inlet, near Station 9, but specimens were found towards the mouth.(Fig. XlX-lf). However, patches were also found at other shallow depths near the mouth in June and August (Figs. XlX-ld, le), when the high-est numbers were in the northern.inlet. The second copepodid stage (Fig. XIX-2) seems to be similar in its occurrences to stage III, but in general i t was not distributed as deeply (Fig. XIX-l). The distribution of the fi r s t copepodid stage (Fig. XIX-3) i s also similar to stage II and III, but i t occurred in shallower waters than stage II; apart from August, highest numbers were more usual i n the southern part of the inlet than was so in stages II to IV (Figs. XVIII-4, XIX-1, 2, 3). Distribution of Gaetanus armiger The distribution of G. armiger was confined in deep water, below 60m. However, specimens were collected at the upper levels, and occasionally near the surface, but not in large numbers (Figs. XX, XXl). This species was not found at the Station 23, just outside the mouth of Indian Arm, and only very few specimens of the later stages (stage IV to adult females) 68 were collected from Station 15, just inside the mouth. Adult males were collected only i n December, I960 and February, 1961 (Figs. XIX-4a, 4b). In December, specimens were concentrated near the bottom, at Station 9; they were not collected from levels above 90m. In February, 1961 (Fig. XIX-4b), they were collected i n high numbers below 120m at Station 6. . Adult females were comparatively wide spread i n the i n l e t , but mostly aggregated at depths between about 60m and 90m. They were frequently collected from Stations 6 and 9 (Fig. XX-l) and sometimes as i n June and August, from Station 12 (Figs. XLX-ld, l e ) . Copepodid V (Figs. XX-2, 3) was distributed similarly to the adult females; they did not occur above 90m. Sexual characters can be differen-tiated i n copepodids IV and V. However, there does not appear to be any differences i n the distribution of sexes for these stages (Figs. XX-2, 3), except i n February, 1961, when stage V males were not collected although females were present (Figs. XX-2b, 3bj. The fourth copepodid stage (Figs. XX-4, XXJE-l), during June, August, and September when i t i s abundant, was distributed over the length of the i n l e t north of Station 15; i t did not occur above depths of 30m. Its centre of concentration was about 90m as with stage V (Figs. XX-2, 3}. There were only slight differences of distribution between male and female stage IV, e.g. males were not collected i n December, I960, but also only a few females were present. The earlier stages, copepodids I, I I , and III, were confined i n the depths below 90m (Figs. XXI-2, 3, 4). Copepodid I (Fig. XXI-4) was collected 69 mostly at the 150m level; stage II (Fig. XXI-3) occupied a \idder area than stage I with concentration up to 120m. Copepodid III (Fig. XXI-2) occupied a wider area than stage I and stage II, and also occurred in high numbers up to 120m. It seems that as the stages succeed one another, the later stage spreads throughout a wider area. 70 VIII. DISCUSSION (The Distribution of Copepods in relation to Oceanographic Conditions) The vertical distribution of Calanus finmarchicus has been reported on by many previous authors. Earlier reports have indicated that the younger stages were near the surface (Gran, 1902; With, 1915). StBrmer (1929) reported that the copepodid stages III to V were in water between 50m and 100m, the adults in 50m to 300m in the Norwegian Sea. Clarke (1933, 1934) found that the adults were deeper in the water than the juveniles. Gardiner (1933). in the North Sea showed that copepodids III and IV lived in the upper layers (above 10 fathoms) and stages V and VI were deeper. Nicholls (1933), in.the Clyde Sea, found that stages I to III stayed between the surface and 30m, while copepodid IV and V, and the adults were variously distributed around 100m. Farran (1947) reported that the copepodid stages IV and V were collected from much deeper levels than the adults. Filteau (1947) reported that copepodid stages III and IV live at about 25m, stage V between 25m and 50m deep, and the female lives deeper. Cushing (1951) suggested that animals living in deep waters (Calanus) may have young that live nearer the surface. Ponomareva (1957) found that in the Kara Sea, the nauplius was always between the surface and 25m; copepodid I was usually between surface to 50m, but might descend to 200m depth; copepodid II was collected from 100m to 200m, III from 50m to 100m, IV from a l l depths, and V and VI at 100m to 200m during the day. At night, copepodids I to II occurred between 25m and 50m, and the adults were concentrated between 50m and 100m. Only Farran (1947) and Ponomareva (1957) of the above accounts suggest that some of the younger stages of Calanus may live regularly at levels deeper than the adult females. A l l others indicate that in general adults live deep-er than stages I to IV, while stage V may occur over a similar range of depth 71 to -the..adult. No informatiori has been found i n the literature concerning the vertical distribution of Gaetanus armiger. From the data of the present study, i t appears that the vertical distribu-tion of the copepodid stages of Calanus i s fairly regular. The younger stages I to III were distributed in the shallow depths, above 90m; stage IV was present in deeper water than the previous stages, down to 150m. Stage V was found over a wide range of depth and in the deep water below 100m; the centres of concentration which were found in shallow depths in late winter and spring seasons (Figs. XVTII-3b, 3c) may have been due to the water movements and l i f e history processes. Adults tend to be concentrated at the intermediate depths of the inlet. These results agree with the previously mentioned studies. In Gaetanus, stages I to V were distributed below 90m depth. Copepodid I aggregated at about the 150m level (Figs. XXI-4), but each successive stage up to adult females spread over a wider range. Occasionally adult females were present near the surface at night (Fig. XX-lb, Id). It was previously shown that the selected xvater properties of temperature, salinity, and dissolved oxygen were regularly distributed, with low oxygen concentration, low temperature, and high salinity towards the bottom (Figs. XIII-1, 2, 3). The T-S-P, 0-S-P, and 0-T-P diagrams indicated relationships of organisms to these properties, namely that Calanus adults not only tended to associate with properties principally of intermediate and shallow water, but also to some extent of deeper waters, whilst Gaetanus inhabited water with properties of intermediate and deeper waters. The distributions of the 72 species in the inlet also show those relationships with depth. It might be concluded, therefore, that the species occurrences were related to depth rather than to water properties. However, this is probably not so. The T-S-P, O-S-P, and O-T-P diagrams show that the adult males and females of the two species, as well as each copepodid stage, occur;., within particular ranges of properties. Despite the absence of specimens at times, due to the seasonal nature"of their l i f e histories, these two species have, i n general, contrasting distributions throughout the year. This suggests either that each species selects one environment in which conditions are more suitable than another, or that water properies elsewhere in the inlet prevent i t from entering the other water. In this sense, species tolerance to water properties would control its occurrences. These properties may be temperature, salinity, and oxygen, although the differences and overlapping of occurrences of Calanus and Gaetanus in the several diagrams would suggest otherwise. It would seem that the particular properties to which species might be reacting should be sought: (l) in the intermediate, and shallow waters to "exclude" Gaetanus, but to "include" Calanus; (2) in the deeper water to "include" Gaetanus but not to "exclude" Calanus. These also indicate that Calanus may be more tolerent than Gaetanus to whatever these other properties may be. While the T-S-P, O-S-P, and O-T-P diagrams may be considered, therefore, as indicating preferences of species to particular conditions of temperature, salinity, and oxygen, they do not necessarily show that these properties are the actual factors controlling their occurrences. The regular association of Gaetanus with the deeper water would indicate that the particular property to which i t was reacting was confined in the deeper water. The widespread occurrences of Calanus indicate that i t was tolerant of this deep water 73 property and also possibly of some other property in the shallower water. Furthermore, not only do the species differ in their tolerances, but also the adult male and female and the several copepodid stages of one species may also differ from each other. This is shown, in Calanus for example, by a tendency for tolerance towards waters with higher temperature and oxygen concentration and lower salinity, in the earlier stages, but to lower tem-perature, less oxygen concentration, and higher salinity for later stages. The opposite trends in tolerance occur in copepodids of Gaetanus armiger, although adult males are similar to those in Calanus i n their restricted range of requirements compared to females. The associations between species and particular properties of water within Indian Arm may also occur wherever the species are present outside the inlet. If so, and i f this water should enter Indian Arm, carrying the species with i t , i t should be possible to detect the entry of the water by the presence of the species in i t . As already demonstrated, for the period being considered Gaetanus was confined in waters with properties of the deep water of the inlet. Further-more, no specimens were collected during the survey at Stations 15 and 23, situated respectively just within, and over, the s i l l at the mouth (Fig. 1-2). Either Gaetanus did not enter the inlet during the period, or i t did so at times other than when sampling was being carried out. It is more likely that specimens did not enter as the properties of the deep water were l i t t l e changed during the survey suggesting that l i t t l e i f any water with these properties entered the inlet. Calanus on the other hand, has been shown to tolerate waters with wide ranges of oxygen concentrations, salinities, and temperatures. It would 74 seem, therefore, that Calanus could indicate the entry into Indian Arm of waters in which properties were the same as, or different from those of the deep water. The distributions of several stages of Calanus in the inlet .'. (Figs. XVTII-1, 2, 3, 4; XIX-1, 2, 3) suggest at times that they ware, in fact, entering in inflowing water. In December, I960, mixing and dilution were suggested (see Discussion of Oceanographic Conditions). Few specimens of the two copepod species were collected. Little information i s to be obtained from their distribution (Figs. XvTII-2a, 3a, 4a; XIX-4a; XX-la, 2a, 3a; XXI-la). Light effect should be considered as a contributory factor in the distribution of copepods (Russell, 1926; Moore, 1955; Moore and O'Berry, 1957). Measurements of light were incomplete during the investigation, due to instrumental deficiencies. They cannot be discussed therefore in detail. However, some series of samples reported on were collected by day and others by night. There are some indications of changes in distribution resulting from diurnal vertical movements of the species. In February, 1961, plankton samples were collected during darkness and on into daylight (from 0332 to 0957 a.m. of February 22nd). Both species of copepods occurred at shallower depths than in tows made only in daylight, probably as a result of upward diurnal migration. Although females of Gaetanus ; migrated upward, they did: not:, reach the surface as females of Calanus did. The different locations of the main centres of concentration of the two species were maintained, although not as clearly as in daytime tows (Figs. XVIII-2b, 3b; XX-lb, 3b). The concentration centres of Calanus adult females and stage V in February were at Stations 6 and 9 at levels above 100m. A few specimens of 75 both species were distributed evenly between the surface and 60m along the southern part of the inlet. This may suggest that the incoming water carried Calanus stock into the inlet from outside. At the same time, Gaetanus females occupied deeper water, with a concentration centre in the southern part of the basin (Fig. XX-lb). Adult males and stage V females of Gaetanus-occurred in deep water below 100m. These distributions do not suggest that incoming water either flowed into the deep water, or carried Gaetanus into the inlet. In April, the distributions of a l l stages of Calanus, except the adult males and females (Figs. XVIII-lc, 2c, 3c , 4c; XIX-lc, 2c, 3c) suggested an incoming population. The distributions of water properties (Figs. X l l l - l e , 2e, 3e) did not indicate an inflow in April, but they showed there was a strong, subsurface inflow in March. It may be that in April, the outside conditions were not very different from those inside the inlet. On the other hand, the distributions of specimens may be/:.reflecti-hg. therrecent past his-tory of water movements into the inlet. In June, samples were again collected during the night. As in February, specimens of adults and later juvenile stages of both species have migrated up to shallower depths. The earlier stages I to III of Gaetanus remained in the deep water, below 90m level (Figs. XXI-2d, 3d, 4d) which suggests that the migration of these stages is either undetected pr that they did not migrate. Stage IV (Figs. XX-4d, XXI-ld) and adult females (Fig. XX-ld) occurred up to depths as shallow as 30m. The distribution of Calanus stages and Gaetanus adults, stage V, IV, and II at Stations 6, 9 , and 12 were discontinuous in June. Such a scattered distribution can not be interpreted from the information available. May be 76 there are other factors applying to this type of distribution which have not been detected. However, the earlier stages of Calanus were concentrated at the mouth of the inlet and may be an indication of the beginning of an inflow. In August, the general distinction between the distributions of Calanus and Gaetanus was maintained. Among juveniles of Calanus, stages I to III occurred near the surface, and the later stages (IV to adults) were deeper (Figs. XVIII-le, 2e, 3e, 4e; XlX-le, 2e, 3e). In addition, the distributions of stages IV and V indicated an intrusion of specimens from the mouth (Figs. XVIII-3e, 4e), but stages I to.Ill suggested a movement in the opposite direction, towards the mouth (Figs. XlX-le, 2e , 3e). The situation may have arisen as a result of breeding in the upper part of the inlet and the young stages spreading down inlet at slightly shallower depths than the older stages were moving into the inlet. An inflow of outside water was not apparent in the distributions of temperature, salinity, and dissolved oxygen, but the distribution of the later stages of Calanus suggest that either such an in-flow was taking place or that there had been a recent inflow. The inclina-tion of the 2 5 . 0 isohaline from the shallow depth of Station 23 (the mouth of the inlet) to 3Cm or more at Station 2 (the head of the inlet) may be an indication that slightly more saline water was flowing in along lines of equal density and carrying the later stages with i t , below outgoing shallower layer. In September, a strong inflow was suggested. The distribution of Calanus showed an incoming stock of younger stages (I to III) in the upper 30m or so. These appear to have been overriding the later stages which were concentrated below this entering tongue with the younger stages. There were indications that, the concentrations of young stages present in August remained, but towards the upper part of the inlet. Perhaps these had been forced up-inlet by the incoming water. 77 The distributions in September of both Calanus and Gaetanus in the deep water appear to have been affected by this inflow. In adult female Calanus, there was a zone on the southern slope of the deep basin in which no specimens occurred (Fig. XVIII-2f); in stage V this contained lower numbers of speci-mens than the more central part of the basin where very high numbers were present. There were only a few stage IV on the southern slope of the basin and no; specimens in the deeper water. In Gaetanus, the distributions of stages III up to adults a l l indicated a zone of zero or low numbers on the southern slope (Figs. XX-lf, 2f, 3f, 4f; XXI-lf, 2f, 3f, 4f). Moreover, the distribution of Gaetanus gives the impression that specimens had retreated before incoming water towards the northern slope of the basin. These data would suggest that some of the inflow was penetrating into the deeper parts of the basin. The above account has been concerned with the relationships of species to water properties and with possible effects of water movements on the dis-tributions of species and their l i f e history stages-in Indian Arm. The T-S-P, 0-S-P, and O-T-P diagrams demonstrated that certain stages of each species occurred in particular ranges of properties. Thus the broad tol-erances of Calanus apparently enable the species to occur throughout the inlet although showing preferences to intermediate and shallow waters. Because they are tolerant, they appear to indicate movements of waters of a variety of properties into the inlet. A similar indication could not be shown by Gaetanus in which the tol-erances were towards a narrow range of properties. In this case, Gaetanus would indicate the entry of only that water possessing those particular properties. The diagrams also indicated a wide range of tolerances among early juveniles of Calanus. The distributions of these early stages in the 78 i n l e t suggest their preference for shallower waters than the adults. In Gaetanus, the early stages, however, were more restricted i n their require-ments and this was reflected i n their occurrences nearer the bottom i n the deepest of the deep water. The study has provided an indication from f i e l d data not only of d i f f e r -ences i n the reactions of two species of Gopepoda towards waters of d i f f e r -ent properties, but also that the reactions of the several stages i n the l i f e histories of the species may d i f f e r from the adults and from each other. These defferences have, i n a general way, been shown to apply i n the distribu-tions of the stages i n the i n l e t . Such general indications are important aids to understanding the distribution of the copepods Calanus and Gaetanus. 79 DC. SUMMARY 1. Four most abundant calanoid copepods from Indian Arm, a fjord-type i n l e t located near Vancouver, B. C , have been studied systematically. They are identified as Calanus sp., Gaetanus armiger Giesbrecht, Pareuchaeta japonica (Marukawa), and Metridia sp.. 2. Morphologically, Calanus sp. can be separated into two size groups: the "large" form resembles Calanus glacial -i s Jaschnov, and Calanus finmarchicus (Gunnerus); the "small" form i s f a i r l y similar to Calanus pacificus Brodsky. But resemblances and differences suggest the two local forms need a more advanced study on both morphology and ecology. 3. The male and copepodid stages of Gaetanus armiger Giesbrecht are described for the f i r s t time. 4. Pareuchaeta japonica (Marukawa) was previously regarded as Euchaeta japonica Marukawa i n this area. Distinctive morphological characters have i been used by other investigators to diagnose two genera Pareuchaeta and Euchaeta which were contained within the Euchaeta. The characters of the two genera are reviewed i n relation to the l o c a l species. 5 . Metridia sp. has been differntiated from the species of the North Atlantic (Metridia lucens Boeck) and Southern California (Metridia sp., Esterly, 1 9 2 4 ) . Information on Metridia pacifica Brodsky, from the Japan Sea, was inadequate for a f u l l comparison to be made and therefore the Identity of material from Indian Arm i s l e f t open; a direct comparison between the l o c a l specimens and specimens from Japan i s necessary. 80 6. Two breeding seasons of Calanus sp. during the year, in spring and late summer, were found.. Gaetanus armiger i s believed to have one breeding season, during spring and summer. 7. Consideration of oceanographic conditions represented by temperature, salinity, and dissolved oxygen have shown that the water in the inlet may be arbitrarily subdivided into three parts; the surface, intermediate, and deep waters. The surface water contains fresh water drained from Indian River and peripheral streams; i t flows out of the inlet at and near the surface. A compensatory flow of water from outside comes in underneath the surface outflow. Conditions in the deep water were fairly stable during the period investigated from December, I960, to September, 1961. 8. Temperature and dissolved oxygen decreased and salinity increased down-wards in the inlet. 9. ' The Temperature-Salinity-Plankton technique has been applied to show the relationships between plankton and water properties of temperature and salin-ity. The principle has also been applied to the construction of Oxygen-Salinity-Plankton and Oxygen-Temperature-Plankton diagrams. Relationships of species to temperature and salinity, oxygen and salinity, oxygen and temperature were demonstrated. These relationships were maintained during the period investigated. 10. Calanus sp. and Gaetanus*' armiger were selected i n order to show the relationships between temperature, salinity, oxygen and copepods. Differ-ences with regard to the three factors were found not only between the two species, but also between the several copepodid stages of each species. 81 11. The earlier copepodid stages of Calanus sp. were more usually distribu-ted in the upper levels; each subsequent stage may occur over a greater range of depth than the preceding stage. Copepodid ? was widespread, but aggregated in higher numbers in deeper water; i t was not found in surface and shallow subsurface waters. Adult females may occur over the whole inlet, but they tend to concentrate 60m and 90m levels. Adult males were collected from deep and intermediate depths. 12. Geatanus armiger was confined i n deep water of the basin. Adult females and copepodid V may occur in the intermediate water, but mostly they con-centrated at depths about 90m. The earlier stages were found in the deep water between about 120m and 150m. 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Sci., Washington 6, D. C. (Trans. Inst. Oceanol. Acad. Sci. USSR, 20: 185-198). Rees, C. B., 1949. Continuous plankton records: the distribution of Calanus  finmarchicus (Gunnerus) and i t s two forms i n the North Sea, 1938-39. Hull Bull . Mar. Ecol.,. 2: 215-275-Rose, M.,. 1933. Copepodes Pelagiques. Faune de France, Paris, 26: 1-374. Rund, J. T., 1929. On the biology of copepods of Mjzfre, 1925-1927. Rapp. Cons.. Explor. Mer., 56: 1-57. Runnstr^m, S., 1932. Eine Uebersicht tiber das Zooplankton des Herdla und Hjeltefjordes. Bergeus Mus. Aarb., 7: 1-67. Russell, F. S., 1926. The v e r t i c a l distribution of marine macroplankton, IV. The apparent importance of l i g h t intensity as a controlling factor i n the behaviour of certain species i n the Plymouth area. J. Mar. B i o l . Ass. U. K., 14: 415-440. Russell, F. S., 1928. The ve r t i c a l distribution of marine macroplankton, VII. Observations on the behaviour of Calanus finmarchicus. J. Mar.  B i o l . Ass. U. K., 15: 429-454. Russell, F. S., 1951. A re-examination of Calanus collected off Plymouth. J. Mar. B i o l . Ass. U. K., 30: 313-314. Salmon, J . T., 1949. New methods i n microscopy for the study of small insects and arthropods. Tans. Roy. Soc. New Zealand, 77 (5): 250-253. Sars, G. 0., 1903. Copepoda Calanoida. An account of the Crustacea of  Norway, Bergen Museum, 4: 1-144. Sars, G. 0., 1925. Copepodes particulierement bathypelagiqu.es provenant des Campagues Scientifiques du Prince Albert l e r de Monaco. Result  Camp. Sci. Monaco, 69: 1-408. Scott, A., 1909. The Copepoda of the Siboga Expedition, Part I. Free swimming, l i t t o r a l and semi-parasitic Copepoda. -Siboga Exped., Monogr., 29a: 1-323. Sewell, R. B. S., 1947. The free-swimming planktonic. Copepoda, Systematic account. John Murray.Exped. Sci. Rept., 8: 1-303. Sewell, R. B. S., 1948. The free-swimming planktonic Copepoda, Geographical distribution. John Murray Exped. Sci. Rept.,. 8 (3): 317-592. 87 S^ mme, J. D.,..1934. Animal plankton of the Norwegian coast waters and the open sea, I. Production of Calanus finmarchicus (Gunnerus) and Calanus  hyperboreus (Kroyer) in the Lofoten Area. . Fiskeridir. Skr. Havundersgfo. (Rept. Norw..Fish. Mar. Invest.), 4 (9): 1-163. Stormer, L., 1929. Copepods from the Michael Sar Expedition, 1924. Rapp. . Cons. Explor. Mer., 56 (7): 1-57. Ussing, H. H., 1938. :The biology of some important plankton animals in,the fjords of east Greenland. Medd. Greenland, 100 (7): 1-108. Vervoort, W., 1952. Copepoda, Sub-order Calanoida, Family Aetideidae, Genus Gaetanus. Zooplankton Sheet, Cons. Explor. Mer., 46: 1-5. Wheeler, W. M., 1900. The free swimming copepods of the Woods Hole region. Bull. U. S. Fish. Comm., 19: 157-192. Wiborg, K. F., 1934. The production of zooplankton in the Oslo fjord in 1933-1934 with special refernce to the copepods. Hvalrau. Skr., 21: 1-87. Wiborg, K. F., 1954. Investigations on zooplankton in coastal and offshore waters of western and northwestern Norway with special reference to the copepods. Fiskeridir. Skr. Havundersgflc., 11 (2): 1-246. Wilson, C. B., 1932. The copepods of the Woods Hole region, Massachusetts. Bull. U. S. Nat. Mus., 158: 1-635-Wimpenny, R. S., 1937. The distribution, breeding and feeding of some important plankton organisms of the southwest North Sea in 1934- Part I. Calanus finmarchicus.jGunnerus), Sagitta setosa (J. Mttller), and Sagitta  elegans (Verrill). "Fish. Invest. Lond. Ser. 2, 15 (3): 1-53. With, C, 1915. Copepoda, I. Calanoid Amphaskandria. Danish Ingolf Exped. Copenhagen, 3 (4): 1-248. 88 XE. LIST OF TABLES 1. Proportional lengths of the segments of metasome of Calanus sp. 2. Proportional lengths of the segments of urosome of Calanus sp. 3. Proportional lengths of the; segments of f i r s t antenna of Calanus sp. 4. Frequency of occurrence of tooth-number on the left f i f t h coxa (coxo-podite) of female Calanus sp. in relation to metasome length. 5. Frequency of occurrence of tooth-number on the left f i f t h coxa (coxo-podite) of male Calanus sp. i n relation to metasome length. 6. Variation in number of setae on the external margin of the third endo-podal segment of the f i f t h leg in relation to variation of metasome length for different months in Calanus sp. female. 7. The shape of the frontal part of the head of Calanus sp. female i n relation to seasonal variation of metasome length. 8. The position on the second exopodal segment of the left f i f t h leg to which the distal end of the left f i f t h endopodite extends in relation to seasonal variation in metasome length of male Calanus sp. 9. Comparison of Calanus spp. in the Northern Hemisphere. 10. Proportional lengths of the segments of metasome of Gaetanus armiger. 11. Proportional lengths of the segments of urosome of Gaetanus armiger. 12. Proportional lengths of the segments of fi r s t antenna of Gaetanus  armiger. 13. Comparison between Gaetanus armiger and Gaetanus kruppii. 14. Proportional lengths of the segments of metasome of Pareuchaeta japonica. 15. Proportional lengths of the segments of urosome of Pareuchaeta japonica. 16. Proportional lengths of the segments of f i r s t antenna of Pareuchaeta  japonica. 17. Comparison between Euchaeta and Pareuchaeta. 18. Proportional lengths of the segments of metasome of Metridja'sp. 19. Proportional lengths of the segments of urosome of Metridia sp. 20. Proportional lengths of the segments of fi r s t antenna of Metridia sp. 89 21. Comparison of the species Metridia lucens Boeck, M. boecki Giesbrecht, and M. pacifica Brodsky. 22. The variation i n the number of segments on f i f t h legs i n relation to the maturity of ovary i n female Metridia spp.. 23. The percentage of specimens occurring i n different populations of female !Metridia with furcae longer, equal to, and shorter than the anal segment. 24. A comparison of the percentage length of shorter to longer legs of the f i f t h pair i n Metridia spp. males for .different populations. 25. Summary of body length measurements of Metridia spp.. 26. Total body lengths (mm) of Metridia populations examined from Indian Arm, North Atlantic, and Southern California. 27. Comparison of the species Metridia spp.. 28. Measurements of the diameter of Gaetanus armiger eggs. 29. Comparison of the copepodid stages of Gaetanus armiger. 30. The maximum and minimum temperature, s a l i n i t y , and oxygen records i n Indian Arm, B. C. from December, I960, to September, 1961. 31. The. maximum and minimum values of temperature, s a l i n i t y , and oxygen i n which the copepodid stages were found. TABLE 1. Proportional lengths of the segments of metasome of Calanus sp. Form Sex N o « of specimens measured Head Th-1 Th-2 Th-3 Th-4 Th-5 Total Female Male 25 20 44 47 16 15 11 11 10 10 9 9 10 8 100 100 Large Female Male 17 5 42 46 17 16 12 11 11 10 9 9 9 8 100 100 TABLE 2. Proportional lengths of the segments of urosome of Calanus sp. Form Sex No. of specimens measured Ab-1 Ab-2 Ab-3 Ab-4 Ab-5 Furca Total Small Female Male 25 20 29 19 10 24 19 14 17 21 100 14 16 17 100 Large Female Male 17 5 29 19 11 26 18 14 17 21 100 15 13 17 100 TABLE 3. Proportional lengths of the sesaents of f i r s t antenna of Calanus sp. Form Sex No. of specimens measured 1 2 3 4 5 6 7 8 9 10 11 12 -Small Female Hale 25 20 47 66 32 29 29 29 29 24 26 34 34 40 120 34 29 31 31 29 23 23 31 34 39 Large Female Male 17 5 43 70 32 28 30 28 30 26 28 35 36 41 115 35 29 31 33 31 23 21 33 35 39 13 14 15 16 17 18 19 20 21 22 23 24 25 Total 45 47 47 50 50 50 50 42 42 40 40 34 45 1000 44 47 47 47 50 50 50 42 44 42 39 37 37 1000 45 47 47 47 47 47 49 43 43 41 38 36 43 1000 47 49 49 49 49 49 51 43 43 41 39 35 31 1000 91 TABLE 4. Frequency of occurrence of tooth-number on the left f i f t h coxa (coxopodite) of female Calanus sp. in relation to metasome length. No. of Sum Length of metasome (mm) Sum Teeth 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3-2 Small females Barge females 15 3 2 1 16 17 1 1 1 1 18 1 1 1 19 3 1 1 I 2 1 1 4 20 9 2 1 3 3 1 1 1 3 21 8 1 1 1 3 2 1 2 3. 22 13 1 9 2 1 2 1 2 2 2 3 10 23 8 1 1 1 4 1 1 1 3 1 5 24 7 1 3 1 2 2 4 ' 1 2 1 10 25 • 10 1 3 3 3 2 1 7 1 11 26 8 1 3 4 1 1 2 2 2 7 27 4 1 3 1 3 2 6 28 1 1 1 1 1 3 1 7 29 4 2 2 1 1 2 1 5 30 2 1 1 1 2 3 31 1 1 2 32 1 1 1 1 2 33 1 1 34 35 36 1 1 37 38 39 1 1 Total 3 2 7 28 25 19 5 14 21 23 15 7 1 Note: 1. Sum of specimens of small females to the left. 2. Sum of specimens of large females to the right. 3. Number of overlapping specimens (2.6mm) have not been included in the sums of either "small" or "large" forms. TABLE 5-Frequency of occurrence of tooth-number on the left f i f t h coxa (coxopodite) of male Calanus sp. in relation to metasome length. Length of metasome ( mm) No. of Sum Sum Teeth 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 Small males Large males 15 1 1 16 3 1 1 1 17 5 1 1 2 1 IS 8 1 2 2 I 1 1 1 1 19 5 2 3 1 1 20 8 1 2 5 21 5 2 2 1 1 1 1 3 22 8 1 4 2 1 23 8 2 3 1 2 1 1 1 3 24 4 1 1 2 1 1 2 25 2 1 1 26 1 1 27 7 1 1 2 3 28 2 2 29 2 2 Total 1 3 9 16 19 10 7 2 2 3 6 1 Note: 1. Sum of specimens of small males to the left . 2. Sum of specimens of large males to the right. 3. Overlapping between 2.5mm and 2.6mm. 93 TABLE 6. . Variation in number of setae on the external margin of the third endopodal segment of f i f t h leg in relation to variation of metasome length for different months in Calanus sp. females. Month No. of setae Length of Metasome (mm) Total No. of spns. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3-0 3-1 3.2 Oct.60 1 1,2 2 1 6 3 2 1 1 1 13 2 Nov.60 1 1,2 2 1 3 1 5 Dec.60 1 1,2 2 1 2 1 4 1 1 9 1 Jan.6l 1 1,2 2 3 1 1 ' 3 1 2 1 1 2 1 11 1 4 Feb.61 1 1,2 2 2 6 4 3 1 1 3 3 3 2 16 12 Mar.61 1 1,2 2 1 1 2 1 1 3 3 2 1 1 1 1 1 16 1 2 Apr.61 1 1,2 2 1 4 3 3 1 3 4 1 2 2 1 1 20 4 2 Jun.6l 1 1,2 2 1 4 5 1 1 3 2 2 2 21 Aug.61 1 1,2 2 2 3 2 3 1 1 1 12 1 Sep.61 1 1,2 2 4 2 5 4 1 1 15 1 1 Total spns. 1 1,2 2 3 1 7 25 24 18 5 9 19 13 9 4 1 2 2 1 4 1 1 1 1 3 1 6 6 3 94 TABLE 7. The shape of the frontal part of the head of Calanus sp. female in relation to seasonal variation of metasome•length. Month Shape of head Length of metasome (mm) Total No. of spns. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 Oct.60 C R 1 6 3 2 1-1 1 13 2 Nov.60 C R 1 3 1 5 Dec.60 C R 1 2 1 3 1 1 1 7 3 Jan.61 C R 2 1 1 1 4 4 3 3 13 Feb.61 C R 1 5 6 7 6 2 1 1 27 Mar.61 •C R 1 1 2 1 1 3 3 4 1 2 5 14 Apr.6l C R 1 7 3 3 3 3 4 2 14 12 Jun.6l C R 1 4 5 1 1 3 2 2 2 11 10 Aug.61 C R 2 3 2 3 1 1 1 10 3 Sep.61 C R 1 4 2.5 4 1 16 1 Total spns. C R 3 2 7 - 28 24 17 4 1 2 1 1 4 2 1 23 15 7 1 85 85 Note: C = Convex rounded; R = Smoothly rounded. 95 TABLE 8. The position on the second exopodal segment of the left f i f t h leg to which the distal end of the left f i f t h endopodite extends in relation to seasonal variation in metasome length of male Calanus sp. Month Propor-tional length Length of metasome (mm) Total No. of spns. 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 Oct.60 V 3 1/2 1 1 1 5 2 10 Nov.60 V3 V2 2 1 3 Dec.60 1/3 1/2 Jan.61 1/3 1/2 1 1 Feb.61 1/3 1/2 2 1 1 1 2 4 5 6 Mar.61 1/3 1/2 2 3 3 1 8 1 Apr.6l 1/3 1/2 1 1 2 2 1 1 1 1 7 3 Jun.6l 1/3 1/2 2 2 2 3 2 1 1 12 1 Aug.61 1/3 1/2 4 6 1 1 2 14 Sep.61 1/3 1/2 1 2 2 3 8 Total spns. 1/3 1/2 1 3 9 16 18 10 7 2 1 1 1 3 6 1 67 12 TABLE 9. Comparison of Calanus spp. in the Northern Hemisphere. C. glacia- Calanus sp. C. finmar- C. helgo- C. helgb- Calanus sp. C. pacificus Species l i s (Large form chicus landicus landicus (Small form (Japan Sea) Indian Arm) (North v. ponti- Indian Arm) C haracte r s \ cus(Black Sea) Body length, average mm. (No. of speci-mens meas'd) a)5.05 (30) 3.86 (17) a ) 3 > ? 3 (24) a^3.12 (29) B V . l -3.6 3.10 (25) a>2.76 (18) Frontal head shape Smoothly rounded Protuberance Smoothly convex rounded Tooth-line on 5th coxopodite Slightly concave Straight Strongly concave fcLeft 5th endo-pod distal end reaches to 2nd exopod segment About 1/2, or more Less than 1/2 About 1/3 Less than 1/3 No.of teeth on 5th coxopodite c)34-35 25 c)32_33 c b o - 3 1 °)24-25 22 °)20-21 % in popu- ^ lation with No.of setae o n ]_ 2 external ' margin of 3rd endo- ^ podal seg. (No.of spns. examined) C V ^20 c ) 3 9 (100) 69 8 23 (85) c ) ? 1 c>4 c>25 (100) c>96 c) 0 e>4 (50) c ) 9 0 c) 2 c>8 (50) 94 2 4 (85) c^100 •) 0 •> 0 (20) Note: Male only, the rest are females'. a)Brodsky (1950). b)Jaschnov (1955). c)Jaschnov (1958). 97 TABLE 10. Proportional lengths of the segments of metasome of Gaetanus armiger. Sex N o > o f SP6'0*""**!8 Head+Th-1 Th-2 Th-3 Th-4+5 Total measured Female 24 68 12 10 10 100 Male U 68 12 10 10 100 TABLE 11. Proportional lengths of the segments of urosome of Gaetanus armiger. _ No. of specimens ., _ ., „ „ ., r „ m . n Sex , Ab-1 Ab-2 Ab-3 Ab-4 Ab-5 Furca Total Female 24 30 22 16 16 16 100 Male 11 13 30 24 19 14 100 TABLE 12. Proportional lengths of the segments of f i r s t antenna of Gaetanus armiger. Sex N o * of specimens measured 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 -Female Male 24 11 55 52 25 25 28 28 31 55 48 31 24 27 27 27 46 25 25 25 43 40 46 62 31 31 31 34 41 16 17 18 19 20 21 22 23 24 25 Total 49 49 52 61 55 46 61 59 52 22 1000 48 51 55 68 106 69 65 69 1000 98 TABLE 13. Comparison between Gaetanus armiger and Gaetanus kruppii. Character's"""" •—>^____Species G. armiger G. kruppii Total body length Male"16 2.9-3.2mm 2.8-3.1mm 3.6- 5.7mm 3.7- 5.6mm Fir s t antenna extends Not beyond the di s t a l end of genital segment. To the di s t a l end of furcae. Spines on the postero-lateral corners of metasome. Long and straight extending to the mid-portion of genital segment. Short and slig h t l y curved ventrally. TABLE 14. Proportional lengths of the segments of metasome of Pareuchaeta .japonica. No.of specimens , ™ , m . « m , « m , i . - m . . Sex measured Head+Th-1 Th-2 Th-3 Th-4+5 Total Female 15 60 12 12 16 100 Male 12 59 12 12 17 100 TABLE 15. Proportional lengths of the segments of urosome of Pareuchaeta .japonica. No. of specimens _ „_ „ , , Sex measured A b ~ 1 A b ~ 2 A b ~ 3 A b ~ ^ A b"" 5 T o t a l Female Male 15 37 22 20 8 13 100 12 16 29 27 18 10 100 99 TABLE 16. Proportional lengths of the segments of f i r s t antenna of Pareuchaeta japonica. No. of specimens measured 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 -Female 15 Male 12 43 40 45 41 22 22 25 23 23 23 25 25 27 27 36 25 27 34 45 42 47 65 23 31 41 41 45 16 17 18 19 20 21 22 23 24 25 Total 52 52 56 70 70 62 58 51 "69 1000 51 53 57 70 70 62 62 53 69 1000 TABLE 17. Comparison between Euchaeta and Pareuchaeta. Euchaeta Pareuchaeta References Terminal spine of 2nd maxilla, female With long spinules Without long spinules Scott, A., 1909 Third exopodal segment of left 5th leg in male Long spiniform process Short and rudimentary Scott, A., 1909 Accessory setae on the furcae Strongly deve-loped, straight Slender with "knee joint" Sars, G.O., 1925 Apical spines on female maxilliped With long spinules With fine short spinules Sewell, 1947 Second exopodal segment of right 5th leg in male Distal end pointed Distal end blunt Genital protu-berance on the ventral surface of genital seg-ment in female Perpendicular or protrudes anteriorly on the genital segment. More or less protrudes posteriorly on the genital segment. TABLE 18. Proportional lengths of the segments of metasome of Metridia sp. S e x N ° * measured116113 H e a d T h " 1 T h ~ 2 T h ~ 3 T h _ 4 + 5 T o t a l Female 50 45 18 11 10 16 100 Male 20 45 17 12 10 16 100 'TABLE 19. Proportional lengths of the segments of urosome of Metridia sp. S e x N ° * m e a g r e ? 6 1 1 3 ^ A b ' 2 A b ~ 3 k h ~ U A b " 5 P u P c f t T o t a l Female 50 37 27 17 19 100 Male 20 13 20 18 18 13 18 100 TABLE 20. Proportional lengths of the segments of f i r s t antenna of Metridia sp. of specimens measured 1 2 3 4 5 6 7 8 9 10 11 12 13 14 -Female Male 50 20 103 33 33 32 32 30 28 28 29 33 34 36 39 43 106 30 30 30 30 30 30 30 30 35 35 35 51 51 15 16 17 18 19 20 21 22 23 24 25 Total 44 47 50 52 53 39 39 38 42 44 19 1000 56 61 71 91 91 77 1000 Note: Measurements for male were on the geniculated f i r s t antenna. 101 TABLE 21. Comparison of the species Metridia lucens Boeck, Metridia boecki Giesbrecht, and Metridia pacifica Brodsky. M. lucens M. boecki M. pacifica Shape of the front head in lateral aspect. Oval rounded Spherical rounded No. of segments on fif t h legs in female. 3 4 3 or 4 Lengths of the ter-minal bristles on f i f t h legs in female. Innermost one, the longest. Equal in length. Length of furca com-. pared vjith anal segment. Equal Furca longer than anal segment. No. of spines on the third and fourth segments of shorter f i f t h leg in male. 1 on 4th segment Unknown 1 on each of 3rd and 4th segments. TABLE 22. The variation in the number of segments on f i f t h legs in relation to the maturity of ovary in female Metridia spp. Locality Segments on fi f t h legs Stage of maturity No.of S] pecimens Immature Mature Ripe Sum Total Indian Arm . B. C. 3 - segmehted 3,4-segmented 4- segmented 6 4 1 ~ 1 1 5 1 3 4 8 8 10 26 North Atlantic 3- segmented 3,4-segmented 4- segmented — 3 4 10 1 8 3 5 18 26 Southern California 3- segmented 3,4-segmented 4- segmented 2 4 18 2 6 18 26 102 TABLE 23. The percentage of specimens occurring in different populations of female Metridia with furcae longer, equal to, and shorter than the anal segment. . N. Atlantic S. California Indian Arm, B. C. No.of specimens mead'd 50 8 61 Furca longer than anal segment. 63% 81% Furca equals to anal segment. 30% 25% 13% Furca shorter than anal segment. 2h% 12% 0% TABLE 24-A comparison of the percentage length of shortervto longer legs of the f i f t h pair in Metridia spp. males for different populations. 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87$ No. of specimens Indian Arm,B.C. N. Atlantic S. California M. pacifica 1 2 2 1 1 1 3 l l 1 2 1 2 1 1 2 1 1 1 2 1 1 1 13 11 6 Indian Arm and N. Atlantic Mean# = 79, Variance =13.8; Student »t» = 1.42 Degree of freedom = 22 Mear$ = 81, Variance = 9.3; 0.2>P>0.1 Indian Arm and S. California Mean^ = 79, Variance = 13.8; Student "t" = 1.42 Degree of freedom = 17 Mear$ = 82, Variance = 16.8; 0.2> P>0.1 N. Atlantic and S. California Hean£ = 81, Variance = 9.3; Student "t" =0.57 Degree of freedom = 15 Mean$ = 82, Variance =16.8; P>0.5 Note: Measurement for M. pacifica was taken from Brodsky's drawing (Brodsky, 1950; p. 295, Fig. 201). TABLE 25. Summary of body length measurements of Metridia spp. Locality Species named , • Body length (mm) References Female Male . • • Atlantic M./ lucens •2.1 2.45-2.85 2.5 2.5-2.9 2.5-3.0 2.5-2.9 2.4-2.8 2.0 2.3 2.0-2.3 2.0-2.5 2.0-2.3 1.8-2.3 Boeck, 1964 Wheeler, 1900 Sars, G. 0., 1903 Pesta, 1928 Wilson, 1932 Rose, 1933 Earran, 1948 M. lucens 3-2 2.5-3.2 2.5-4.0 2.4- 3.2 2.5- 2.9 2.3 2.0-3.0 2.3-2.6 2.0-2.3 Esterly, 1905 Campbell, 1929 Mori, 1937 Davis, 1949 Brodsky, 1950 Pacific M. boecki 2.65 2.55 2.5-2.6 Giesbrecht, 1889 Esterly, 1905 Brodsky, 1950 Metridia sp. 2.6 2.1 Esterly, 1924 M. pacifica 2.6-3.1 2.0-2.1 Brodsky, 1950 TABLE 26. Total body lengths (mm) of Metridia populations examined from Indian Arm, North Atlantic, and Southern California. Indian Arm N. Atlantic S. California Female 2.8-3.2 2.6-3.0 2.3-2.4 (No. of specimens mea'd) (50) ( 8 ) ; (8) Male 2.0-2.5 2.0-2.1 1.6 (No. -of specimens mea'd) (20) (9) (1) TABLE 27. Comparison of the species Metridia spp. Indian Arm N. Atlantic S. California M. pacifica Female Male 2.8-3.2 2.0-2.5 2.6-3.0 2.0-2.1 Total body length in mm. 2.3-2.4 1.6 2.6-3.1 2.0r2.1 Blunt Teeth on mandible in both sexes Sharpe Medium blunt Shape of the front head in lateral aspect Spherical rounded Oval rounded Spherical convex rounded Percentage in population with different number of segments on the f i f t h legs in female. 3- segmented" 3,4-segmented 4- segmented 31% ' 31% 38% " 12% ' 19% 69% 8% 23% 69% 63% 25% 12% Percentage in population with variable lengths of furca i n female. i Furca longer than anal segment Furca equals to anal segment Furca shorter than anal segment 13% 0% U6% 30% 2k% Bl% 82% 76% Percentage of the shorter leg to the longer leg of f i f t h pair in male 79% nic in About 1/3 length of 18th segment Lengths of the setae on the ge . segments on the f i r s t antenna ulate male. About i/2 length of 18th segment Less than 1/3 . length of 18th segment Distal spine on the eighteenth segment of the geniculate f i r s t antenna in male. Bluntly pointed Seta-form Bluntly pointed Note: Records of Metridia pacifica from Brodsky, 1950; p. 295> Fig. 201. TABLE 28. Measurements of the diameter of Gaetanus armiger eggs. Mo. of eggs 1 2 3 4 5 6 .7 Egg proper (mm) Outer membrane included (mm) Thickness of membrane (mm) 0.30 0.33 0.33 0.33 0.33 0.33 0.35 0.57 0.53 0.53 0.57 0.73 0.73 0.53 0.27 0.20 0.20 0.24 0.40 0.40 0.18 106 TABLE 29. Comparison of the copepodid stages of Gaetanus armiger. '^^"^^^^ Stages Body parts — I II III IV V VI $ ? ? Total body iength(mm) (No.of specns. meas'd) 0.85 (7) 1.15 (15) 1.55 (12) 2.00 (14) 2.00 (9) 2.70 (7) 2.65 (5) 3.00 (12) 2.85 (7) Segments Metasome . 3'" 4 Segments Urosome 1 2 3 4 Segments First antenna 10 17 22 24 25 21 Segments Second antenna Exopod 7 Segments Endopod 2 Segments Mandible Exopod 4 5 Segments Endopod 1 • 2 Segments F irst maxilla Exopod 1 Segments Endopod 2 3 Segments Second maxilla 3 5 4 Segments Maxilliped 4 5 6 7 Segments Swimming legs 1st Exopod 1 2 3 Segments Swimming legs Endopod 1 Segments Swimming legs 2nd Exopod 1 2 3 Segments Swimming legs Endopod 1 3 Segments Swimming legs 3rd Exopod ... .TT A. 1 2 3 Segments Swimming legs Endopod 1 2 3 Segments Swimming legs 4th Exopod X 1 2 3 Segments Swimming legs Endopod 1 2 3 Segments Swimming legs 5th Exopod X X X X 1 1 3 Segments Swimming legs Endopod 1 1 1 107 TABLE 30* The maximum and minimum temperature, sa l i n i t y , and oxygen records i n Indian Arm, B.C. from December, I960, to September, 1961. Temperature(°C) Salinity( % ) 0xygen(ml/l) Maximum Time Station Depth 20.21 0712, 1, Aug. 61 2 0m 27.36' 1237, 15, Dec. 60 9. 200m 10.51 1905, 26, Apr. 61 23 Om Minimum' Time Station Depth 3.08 0937, 16, Dec. 60 6 0m 3.35 • 2240, 1, Nov. 60 6 Cm 1.35 1236,. 21, Feb. 61 6 200m TABLE 31. The maximum and minimum values of temperature, sa l i n i t y , and oxygen i n which the copepodid stages were found. Temperature (°C) Salinity ( % ) Oxygen (ml/1-) Species Stages - .-Minimum Maximum Minimum Maximum Mini mum Maximum • I 8.0 13.5 10.0 27.0 2.5 10.5 II 8.0 13.5 10.0 27.0 2.5 10.5 III 8.0 14.5 10.0 27.0 2.5 10.0 Calanus .IV 7.5 14.5 10.0 27.0 2.5 9.5 V 7.0 14.5 18.0 27.0 1.5 8.0 Male 7.5 11.5 24.0 27.0 2.0 5.5 Female 5.0 14.5 5.0 27.0 1.5 9.0 ', I 8.0 8.5 26.5 27.0 2.0 4.0 II 8.0 9.0 26.0 27.0 2.0 4.5 III 7.5 9.0 26.0 27.0 2.0 4.5 Gaetanus IV 7.5 9.5 25.5 27.0 2.0 4.5 V 7.5 11.0 25.5 27.0 1.5 5.0 Male 7.5 8.5 27.0 1.5 3.5 Female 7.5 11.0 25.5 27.0 1.5 5.0 108 XII. EXPLANATION OF ILLUSTRATIONS. Plate I: Geography of the area investigated. Fig. 1-1. Locality of Indian Arm, B. C.. Fig. 1-2. Distribution of stations and sampling levels. Plate II: Morphology of Calanus sp.. Fig. II-1. First antenna of female. Fig. II-2. First antenna of male. Fig. II-3. Second antenna of female. Fig. II-4. Second antenna of male. Fig. II-5- Mandible of female. Fig. II-6. Mandible of male. Fig. II-7- First maxilla of female. Fig. II-8. First maxilla of male. Fig. II-9. Second maxilla of female. Fig. 11-10. Second maxilla of male. Fig. 11-11. Maxilliped of female. Fig. 11-12. Maxilliped of male. Fig. 11-13. Dorsal aspect of female (large form). Fig. 11-14. Dorsal aspect of male (large form).. Fig. 11-15. Dorsal aspect of female (small form). Fig. 11-16. Dorsal aspect of male (small form).. Fig. 11-17i First swimming leg of female. Fig. 11-18. Second swimming leg. of female. Fig. 11-19. Third swimming leg of female. Fig. 11-20. Fourth swimming leg of female. Plate III: Morphology of Calanus sp. (continued). Fig. I I I - l , 2, 3, 4. Lateral aspects of female. Fig. III-5, 6, 7, 8. Fifth swimming legs of females in Figs. III-l to 4. Fig. III-9, 10, 11, Lateral aspects of male. Fig. 111-12, 13, 14. Fifth swimming legs of males i n Figs. III-9 to 11. Plate IV: Morphology of Gaetanus armiger. Fig. IV-l. Lateral aspect of copepodid stage I. Fig. IV-2. Lateral aspect of copepodid stage II. Fig. IV-3. Lateral aspect of copepodid stage III. Fig. IV-4- Lateral aspect of copepodid stage IV...(female). Fig. IV-5. Lateral aspect of copepodid stage V (female). Fig. IV-6. Lateral aspect of copepodid stage VI (adult female). Fig. IV-7. Lateral aspect of copepodid stage IV (male). Fig. IV-8. Lateral aspect of copepodid stage V (male). Fig. IV-9. Lateral aspect of copepodid stage VI (adult male). Fig. IV-10. Dorsal aspect of adult female. Fig. IV-11. Dorsal aspect of adult male. Fig. IV-12. Setae on the distal end of furca. 109 Fig. IV-13. First antenna of copepodid stage I. Fig. 17-14. First antenna of copepodid stage II. Fig. 17-15- First antenna of copepodid stage III. Fig. 17-16. First antenna of copepodid stage 17. Fig. 17-17. First antenna of copepodid stage 7. Fig. 17-18. First antenna of copepodid stage VI...(adult female). Fig. 17-19. First antenna of copepodid stage 71 (adult male). Plate 7: Morphology of Gaetanus armiger (continued). Figs. 7-1, 2, 3, 4, 5, 6, 7. Second antenna of copepodid stages I, II, III, 17, 7, 71 (adult female), and 71 (adult male). Figs. 7-8, 9,10, 11, 12, 13, 14. Mandible of copepodid stages (same order as above). Figs. 7-15, 16, 17, 18, 19, 20, 21. First maxilla of copepodid stages (same order as above). Figs. 7-22, 23, 24, 25, 26, 27, 28. Second maxilla of copepodid stages (same order as above). Figs. 7-29, 30, 31, 32, 33, 3k, 35- maxilliped of copepodid stages (same order as above). Plate 71: Morphology of Gaetanus armiger (continued). Figs. 71-1, 2, 3, 4, 5, 6. First swimming legs of copepodid stages I, II, III, 17, 7, 71 (adult female). Figs. 71-7, 8,.9, 10, 11, 12. Second swimming legs of copepodid stages (same orderaas above). Figs. 71-13, 14, 15, 16, 17. Third swimming legs of copepodid stages . II, III, 17, 7, 71 (adult female)., Figs. 71-18,.19, 20, 21. Fourth swimming legs of copepodid stages III, 17, 7, 71 (adult female). Figs. 71-22, 23, 24. Fifth swimming legs of copepodid stages 17, 7, 71, (males). Plate 711: Morphology of Pareuchaeta japonica. Fig. 711-1. Dorsal aspect of female. Fig. VII-2. Lateral aspect of female. Fig. 711-3. Dorsal aspect of male. Fig. 7II-4. Lateral aspect of male. Fig. 7II-5. Terminal portion of left exopodite of f i f t h leg of male. Fig. 7II-6. First antenna of female. Fig. 7II-7. First antenna of male. Fig. 711-8. Second antenna of female. Fig. 7II-9. Second antenna of male. Fig. 711-10. Mandible of female. Fig. 711-11. Mandible of male. Fig. 711-12. First maxilla of female. Fig. 711-13. First maxilla of male. Fig. 711-14. Second maxilla of female. Fig. 711-15. Second maxilla of male. Fig. VII-16. Maxilliped of female. Fig. VII-17. Maxilliped of male. 110 Fig. VII-18. First swimming leg of female. Fig. VII-19. Second swimming leg of female. Fig. VII-20. Third swimming leg of female. Fig. VII-21. Fourth swimming leg of female. Fig. VII-22. Fifth swimming legsvdf male. Plate VIII: Morphology of Metridia sp.. Fig. VIII-1. Dorsal aspect of female. Fig. VIII-2. Lateral aspect of female. Fig. VIII-3. Dorsal aspect of male. Fig. VIII-4. Lateral aspect of male. Fig. VIII-5. First antenna of female. Fig. VIII-6. Ungeniculated f i r s t antenna of male. Fig. VIII-7. Geniculated f i r s t antenna of male in usual form. Fig. VIII-8. Geniculated f i r s t antenna of male (stretched). Fig. VIII-9. Second antenna of female. Fig. VIII-10. Mandible of female. Fig. VIII-11. First maxilla of female. Fig. VTII-12. Second maxilla of female. Fig. VIII-13. Maxilliped of female. Fig. VIII-14, 15, 16, 11, 18. First, 2nd, 3rd, 4th, 5th swimming legs of female. Fig. VIII-19. Fifth pair of swimming legs of male. Plate IX: Morphology of Metridia sp. (continued). Fig. IX-1. Dorsal aspect of an "immature11 female, showing the ovary. Fig. IX-2. Dorsal aspect of a "mature" female, showing the ovary and oviducal diverticula. Fig. IX-3. Dorsal aspect of a "ripe" female, showing the ovary and emptied.oviducal diverticula. . Fig. IX-4- "3-segmented" 5th leg of female (showed in Fig. IX-1). Fig. IX-5- "3, 4-segmented" 5th leg of female (showed in Fig. IX-2). Fig. IX-6. '^ -segmented",- 5th leg of female (showed in Fig. IX-3). -Fig. IX-7' Lateral aspect of female from Indian Arm, B. C... Fig. IX-8. Lateral aspect of female from North Atlantic. Fig. IX-9. Lateral aspect of female from Southern California. Fig. IX-10. Masticatory edge of mandible of female from Indian Arm, B.C.. Fig. IX-11. Masticatory edge of mandible of female from North Atlantic. Fig. IX-12. Masticatory edge of mandible of female from Southern California. Fig. IX-13. Lateral aspect of male from Indian Arm, B. C . Fig. IX-14. Lateral aspect of male from North Atlantic. Fig. IX-15- Lateral aspect of male from Southern California. Fig. IX-16. Masticatory edge of mandible of male from Indian Arm, B. C. Fig. IX-17. Masticatory edge of mandible of male from North Atlantic. Fig. IX-18. Masticatory edge of mandible of male from Southern California. Fig. IX-19. Geniculated segment on f i r s t antenna of male from Indian Arm. Fig. IX-20. Geniculated segment on f i r s t antenna of male from North Atlantic. Fig. IX-21. Geniculated segment on f i r s t antenna of male from Southern California. Fig. IX-22. . Fifth pair of swimming legs of male from Indian Arm. Fig. IX-23. Fifth pair of swimming legs of male from North Atlantic. Fig. IX-24- Fifth pair of swimming legs of male from Southern California. I l l Plate X: Fig. X-l. Histograms showing the frequency of occurrence of adult females of Calanus sp. of different metasome length. Fig. X-2. Histograms showing the frequency of occurrence of adult males of Calanus sp. of different metasome length. Fig. X-3. Regression of the lengths of left endopodite and exopodite of f i f t h leg of male.Calanus sp.. Fig. X-4. Regression of the lengths of right exopodite and le f t exo-podite of fif t h leg of male ^.Calanus sp.. Plate XI: Fig. XI-1. Ine proportional lengths of segments to the total length of the metasome of Calanus sp. (female). Fig. XI-2. The proportional lengths of segments to the total length of the urosome of Calanus sp. (female). Fig. XI-3. The proportional lengths of segments to the total length of the f i r s t antenna of Calanus sp. (female). Fig. XI-4. The proportional lengths of segments to the total length of the f i r s t antenna of Calanus "sp. (male). Fig. XI-5. The proportional lengths of segments to the total length of the metasome of Metridia spp. (female). Fig. XI-6. The proportional lengths of segments to the total length of the urosome of Metridia spp."(female). Fig. XI-7. The proportional lengths of segments to the total length of the f i r s t antenna of Metridia spp. (female). Plate XII: Fig. XII-1. Seasonal fluctuation of population of each copepodid stage of Calanus sp.• • Fig. XII-2. Seasonal fluctuation of population of each copepodid stage of Gaetanus armiger. Plate XIII: Fig. XIII-1. Longitudinal vertical distribution of temperature in Indian . " • . Arm, B. C. """ " ' ' "" Fig. XIII-2. Longitudinal vertical distribution of salinity in Indian Arm, B. C. ^ Fig. XIII-3. longitudinal vertical distribution of dissolved oxygen in .. „. . Indian Arm, B. C, Plate XIV: Relationships between temperature, salinity, and dissolved oxygen and copepods. Fig. X3V-1. A summary diagram showing maximum and minimum temperature and salinity values in relation to occurrences of"copepods. Fig. XIV-2. ACsummary' diagram showing maximum and minimum oxygen and salinity Values' iii' relation" to "occurrences of copepods. Fig. XIV-3. A summary diagram showing maximum and minimum oxygen and temperature values in relation to occurrences of copepods. Plate XV: Relationships between temperature salinity, and copepods. Fig. XV-1. Temperature-Salinity-Plankton diagram showing occurrences of Calanus sp. in relation to temperature and salinity. Fig. XV-2. Temperature-Salinity-Plahkton diagram showing occurrences of Gaetanus armiger in relation to temperature and salinity. Plate XVI.-: Relationships between oxygen, salinity, and copepods. Fig. XVI-1. Qxygeh-Salirri/ty-Plankton diagram showing occurrences of Calanus sp. in relation to oxygen and salinity. Fig. XVT-2. Oxygen-Saliraty-Plankton diagram shoving occurrences of Gaetanus armiger in relation to oxygen and salinity. Plate XVII: Relationships between oxygen, temperature, and copepods. Fig. XVII-1. Oxygen-Temperature-Plankton diagram showing occurrences of Calanus' sp. in relation to oxygen and temperature. Fig. XVII-2. Oxygen-Temperature-Plankton diagram showing occurrences of Gaetanus armiger in relation to oxygen and temperature. Plate XVIII: Longitudinal vertical distribution of copepods in Indian Arm. Fig. XVTII-1. Calanus adult male. " Fig. XVIII-2. Calanus adult female. Fig. XVIII-3. Calanus copepodid stage V. Fig. XVIII-4. Calanus copepodid stage IV. Plate XIX: Longitudinal vertical distribution of copepods in Indian Arm. Fig. XIX-1. Calanus copepodid stage III. Fig. XIX-2. Calanus copepodid stage H. Fig. XIX-3- Calanus copepodid stage I. Fig. XIX-4. Gaetanus adult male. Plate XX: Longitudinal vertical distribution of copepods in Indian Arm. Fig. XX-1. Gaetanus adult"female. Fig. XX-2. Gaetanus copepodid stage V male. Fig. XX-3. Gaetanus copepodid stage V female. Fig. XX-4• . Gaetanus copepodid stage IV male. Plate XXI:: Longitudinal vertical distribution of copepods in Indian Arm. Fig. XXI-1. Gaetanus copepodid stage IV female. Fig. XXI-2. Gaetanus copepodid stage III. Fig. XXI-3- Gaetanus copepodid stage II. Fig. XXI-4. Gaetanus copepodid stage I. Plate XXII: Morphology of Gaetanus armiger. Fig. XXII-1. Gaetanus adult female and egg. Fig. XXII-2. Gaetanus egg. Fig. XXII-3. Ventral aspect of Gaetanus nauplius I. Fig. XXII-4. Dorsal aspect of Gaetanus nauplius I. Plate I 113 Plate II 114 Plate III Plate IV 6 Plate V 117 Plate VI 1 1 8 V I - 5 VI-6 Plate VII Plate v m 1 2 Q Plate IX Plate X •122 30 T 20+ CO LU |0H o UJ CL CO On 2 x - i LARGE FORM Lu O or LU m 20-10-0^  SMALL FORM X - 2 cf Z./4/?t?£" FORM 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 L E N G T H OF M E T A S O M E (mm) X - 3 X - 4 Plate XI 123 Calanus sp. (%.) -+—- SMALL FORM FORM (%o) -50 (%) 50-1 1 1 l l 1 I 20 25 (%) 50-Head Th-1 Th-2 Th-3 Th-4 T h - 5 METASOMAL SEGMENTS X I - 2 S E G M E N T S OF F I R S T A N T E N N A Ab-I Ab-2 Ab-3 Ab-4 Ab-5 Furca UROSOMAL SEGMENTS lOOi X r-CD ~ZL UJ 50 J .< O r-o o_ o cr a. Metridia sp. - INDIAN ARM, B. C. - SOUTHERN CALIFORNIA - NORTH ATLANTIC 0 J — I — l — i — i - H — I — h -I 1 1 1 H H 1 1 h 5 10 15 20 S E G M E N T S OF F I R S T A N T E N N A H—I—I—-t- 25 (%) 50-(%) 50-Head Th-I Th-2 Th-3 Th"4 + 5 M E T A S O M A L SEGMENTS X I - 6 Ab-I*2 Ab-3 Ab-4*5 Furca UROSOMAL SEGMENTS Plate XII 1 24 N U M B E R OF INDIVIDUALS P E R nrf X i Q Q t5 Co Co X i ro 5.] <_ c : J CD O o o H o m o . m CD > 73 CD C_ c CD ^ > c : o 0) m "0 o ro o N U M B E R OF I N D I V I D U A L S P E R m" ro ro ro O o O o o \ h 1 h h -J J J < i < ro o o < • et c; Co ct> m Plate XIII 125 S T A T I O N S 20O-1-T E M P E R A T U R E ( ° C ) S A L I N I T Y (%o) O X Y G E N (ml/ l ) XIII-I XIII -2' XII!-3 Plate XIV 126 I 5 T O o LU rr z> \-<io-or LU Q_ LU 5 - --I 1——H -H I 1 f r- -i 1 1——H 1 1 1 1 1 1-5 1 0 X I V - I 1 5 2 0 S A L I N I T Y (%0) 2 5 10-E LU 5 ->- T X o -c-iv- -c-iii--c-v-r-C-o*-J 6:111 Ar O H — j r -i h "i r- H h I I I h H h X I V - 2 1 0 1 5 2 0 S A L I N I T Y (%o) 2 5 1 0 -E LU C D 5 + >-X O I r-C-9--c-i a //-c-in--c-iv--c-v--c-<f-\G\H\ X H — } j i Calanus sp. Gaetanus armiger — 9 cf v  IV /// // : / 0-1- 1 1 1 1 1 1 H 1 1 1 r— 5 1 0 . 1 5 T E M P E R A T U R E ( °C ) ' X I V - 3 Plate XV 1 2 7 20 \5 _ M N \ T V ^ / o o ) Gaetanus o o armiger o o o o oo ° o o o oo o o t> Plate XVI 1 2 g O O o G> O o Calanus sp. XVI- I H 1 H h H 1 1 1 1 1 ;—I H h 15 20 S A L I N I T Y ( %o ) o o o o o o o o Gaetanus armiger X V I - 2 o o o o o H V H 1 1 1 1 1 1 i h H h 15 20 S A L I N I T Y • ( % < , ) 129 Plate XVII T E M P E R A T U R E ( ° C ) Plate XVIII 130 S T A T I O N S . ? 6 ' 9 I? 15 23 2 t? ? 12 15 2 ? 2 (? 9 '? 15 23 2 g . 9 I? 15 2 ? Plate XIX 131 2 6 9 12 15 2 3 2 6 OTT J 1 1 1 1 L J L S T A T I O N S 12 15 2 3 2 6 9 12- 15 2 3 2 Q ' 9 Ig 15 2 3 S E P . '61 X I X - 2 X I X - 3 X I X - 4 NUMBER OF S P E C I M E N S PER m 3 Plate XX -S T A T I O N S 2 6 9 12 15 23 2 6 9 12 15 23 2 6 9 12 15 23 2- Q 9 12 15 23 X X - I X X - 2 X X - 3 X X - 4 Plate XXI 3_33 S T A T I O N S 2 6 9 12 15 23 2 6 9 12 15 23 2 6 9 12 15 23 2 6 9 12 15 23 XXI-1 XXI-2 XXI-3 XXI-4 Plate XXII , .' 134 XXII- XXII - 2 

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