THE CHAETOGNATHS OP WESTERN CANADIAN COASTAL WATERS by HELEN ELIZABETH LEA A THESIS SUBMITTED IN PARTIAL FULFILMENT OP THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS in the Department of ZOOLOGY We accept this thesis as conforming to the standard required from candidates for the degree of MASTER OF ARTS Members of the Department of Zoology THE UNIVERSITY OF BRITISH COLUMBIA October, 1954 ABSTRACT A study of the chaetognath population in the waters of western Canada was undertaken to discover what species were pre• sent and to determine their distribution. The plankton samples examined were collected by the Institute of Oceanography of the University of British Columbia in the summers of 1953 and 1954 from eleven representative areas along the entire coastline of western Canada. It was hoped that the distribution study would correlate with fundamental oceanographic data, and that the pre• sence or absence of a given species of chaetognath might prove to be an indicator of oceanographic conditions. Four species of chaetognaths, representing two genera, were found to be pre• sent. One species, Sagitta elegans. was the most abundant and widely distributed species, occurring at least in small numbers in all the areas sampled. It was characteristic of the mixed coastal waters over the continental shelf and of the inland waters. Enkrohnla hamata. an oceanic form, occurred in most regions in small numbers as an immigrant, and was abundant to- ward the edge of the continental shelf. Sagitta lyra. strictly a deep sea species, was found only in the open waters along the outer coasts, and a few specimens of Sagitta decipiens. another oceanic form, were also taken in deep hauls from areas exposed to open ocean influence. It was found that the outer limit of Sagitta elegans corresponded with the inner limits of all three oceanic forms, though Eukrohnia hamata invaded the inland waters to some extent. TABLE OP CONTENTS Page 1. INTRODUCTION . 1 2. HISTORY . 2 3. ZOOGEOGRAPHICAL DISTRIBUTION . 3 4. OCEAN0GRAPHIC FACTORS INFLUENCING OCCURRENCE IN BRITISH COLUMBIA . 4 5. AFFINITIES OF THE CHAETOGNATHS . 7 6. ANATOMY OF CHAET OGNATHS .............. 9 Geheralappearance Development and maturity stages 7. MATERIAL . 13 8. TECHNIQUE OF EXAMINATION . 16 9. SPECIES IN BRITISH COLUMBIA 19 Descriptions of Species Eukrohnia hamata Sagitta~eiegahs Sagitta lyra Sagitta decipiens Keys to British Columbia Species 10. DISTRIBUTION AND FREQUENCY OF OCCURRENCE ..... 34 11. DISTRIBUTION IN EACH AREA 36 I Saanich Inlet II Indian Arm III Pehdrell Sound IV Channels north end Strait of Georgia V Bute Inlet VI Queen Charlotte Strait VII Queen Charlotte Sound VIII Hecate Strait IX Dixon Entrance X Masset Sound and Inlet XI West coast Queen Charlotte Islands 12. EVALUATION OF THE DATA .............. 79 13. SUMMARY . 80 14. ACKNOWLEDGEMENTS 82 15. LITERATURE CITED 84 LIST OF ILLUSTRATIONS Plates Page I. Sagitta. diagrammatic drawing, ventral view .... 11 II. Eukrohnia hamata, large maturing and small mature, dorsal views . 21 III. Sagitta elegans, Sagitta decipiens^ and Sagitta lyra, dorsal views ... ........ 27 Maps I. Coast of western Canada, regions investigated ... 14 II. Saanich Inlet - stations ............. 40 III. Indian Arm - stations . ..... 45 IV. Pendrell Sound, Channels, and Bute Inlet - stations 48 V. Queen Charlotte Strait - stations 58 VI. Queen Charlotte Sound and Hecate Strait - stations 61 VII. Dixon Entrance - stations 67 VIII. Masset Sound and Inlet - stations .... , 73 IX. Queen Charlotte Islands - stations along west coast 77 Tables 1. Saanich Inlet, distribution of chaetognaths .... 41 2. Indian Arm, distribution of chaetognaths 46 3. Pendrell Sound, distribution of chaetognaths ... 49 4. Channels north end Strait of Georgia, distribution of chaetognaths . ... 49 5. Bute Inlet, distribution of chaetognaths ..... 55 Page 6. Queen Charlotte Strait, distribution of chaetognaths. 59 7. Queen Charlotte Sound, distribution of chaetognaths . 62 8. Hecate Strait, distribution of chaetognaths 62 9. Dixon Entrance, distribution of chaetognaths .... 68 10. Masset Sound and Inlet, distribution of chaetognaths ..... 74 11. West coast Queen Charlotte Islands, distribution of chaetognaths ......... 78 # » * 1. INTRODUCTION Chaetognaths, or arrow worms, are conspicuous members of the plankton communities of the oceans of the world. More• over in some localities they have been found to be important indicator organisms, certain species being confined to waters with characteristic properties. When the requirements of var• ious species are known, it may be possible to predict the char• acter and origin of a water mass on the basis of the presence therein of a particular species of chaetognath. In the English Channel, for example, where two species are predominant, the abundance of either one of the species gives information con• cerning the source of that particular water, and this knowledge is of value to the herring industry (Kemp,1938). While chaetognaths have been and are being studied ex• tensively in other parts of the world, including the east coast of Canada (Huntsman,1919), very little is known about the spe• cies present off the west coast of Canada or about their distri• bution. Except for the work of Michael (1909-1919) in the San Diego region of California, there are no other published studies of chaetognaths for any area in the eastern Pacific. Therefore, the present study was undertaken to acquire information about the chaetognath fauna of the coastal waters of Canada's western pro• vince of British Columbia, and with the hope, also, that the dis• tribution study would correlate with fundamental oceanographic data, and perhaps form a basis for more extensive plankton studies. 2 2. HISTORY Chaetognaths were first discovered in 1775 by Martin Slabber, who classified them as worms, and gave the species the generic name of Sagitta. The arrow worm was not mentioned again until 1827, when Quoy and Gaimard rediscovered It in the Mediterranean and published a description under the name of Sagitta bipunctata. They also called it in French "Fleche deux points," or arrow with two dots, both names referring to the shape and to the two black spots which they thought might be the eyes. The description was very inadequate, since the animals are transparent and the microscope used was not as good as the modern instruments. Present day interest in the arrow worms dates from the publication of Quoy and Gaimard, but the confusion as to which species of arrow worm was Sagitta blpunctata was not cleared up for many years. Leuchart (1854) created the Order Chaetognatha (Gr. chaite, bristle; gnathos, jaw). Two genera were recognized at that time, one Sagitta (Slabber) and the other Spadella (Langerhans). In 1883 Grass! produced a general work on the whole group, but probably the most important taxonomic contri• butions were made in 1911 by Ritter-Zahony, whose careful and complete descriptions and good drawings have been the basis for all work on identification since that time. Also important were the contemporary works of Michael (1909, 1911) for the San Diego region. Thomson (1947) in Australia has brought up to date all the Information on classification, technique, synonymy, and dis- 3 tribution, and produced an excellent key for all valid species besides compiling an extensive bibliography. According to Thomson, there are now ten genera of chaetognaths, including one fossil form. Seven of these genera are monospecific, in one genus there are two species, in another three, and the genus Sagitta contains twenty-six valid species. Several forms that have been described are still considered doubtful species, and further investigation will be required, especially as to the environmental influence on the characteristics used for classi• fication. 3. ZOOGEOGRAPHICAL DISTRIBUTION While chaetognaths occur in all oceans, the individual species are restricted to different regions, some being deep sea forms, others living in the epiplankton of the open sea, and some inhabiting only the mixed waters over the continental shelves near land. None of the species is completely cosmo• politan, though many have a very wide distribution. Thomson (1947) states that eight of the Indo-Pacific forms do not reach the Atlantic, while five Atlantic species have not been reported from the Indo-Pacific. Species of deep oceanic waters have a wider distribution than those dwelling near the surface, since they are subject to very little temperature change, though in the warmer parts of the world they are found at greater depths than they are in the colder regions. Also the immature stages are often nearer the surface, while the mature ones are in 4 deeper water. Thomson says that the bulk of the chaetognath population, as with the plankton in general, is concentrated in the upper one-hundred meters. Some of the species live at much greater depths, however, and according to Ritter-Zahony (1911b) they have been taken at depths of over 1200 meters. It Is possible that some species could be found in deeper hauls than are ordinarily made. Praser (1949) states that one speci• men of Krohnitta subtalis (Grassi) was taken where the depth exceeded 1800 meters. In a regional study, one must be aware of the fact that the chaetognath population may vary with the season, from one year to another, or with shifts in the currents. Some intensive regional studies have been undertaken, but much of the informa• tion available at present has been obtained through examination of material collected on occasional expeditions. As more regions are thoroughly studied, it will be possible to form a much bet• ter picture of the global distribution of the chaetognaths. 4. 0CEAN0GRAPHIC FACTORS INFLUENCING OCCURRENCE IN BRITISH COLUMBIA In the north Pacific Ocean, the chaetognath fauna has been investigated in the Philippines (Michael,1919), in Japan (Tokioka,1940), and In southern California off San Diego (Michael,1909,1911). It might be expected that species found in any of these regions could also occur in the British Columbia waters. The North Equatorial Current flowing past the Philip• pines becomes the Euroshio Current along the south and east of Japan.