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UBC Theses and Dissertations

The qualitative and quantitative distribution of plankton in the Strait of Georgia in relation to certain.. Legare, Joseph Eugene Henri 1956-12-31

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THE QUALITATIVE AND QUANTITATIVE DISTRIBUTION OF P L A N K T O N IN T H E S T R A I T O F G E O R G I A I N R E L A T I O I TO C E R T A I N OCMNOGaRAPHIC FACTORS by JOSEPH E U G E N E H E N R I USGARB B.SC, LAVAL UNIVERSIW, 1953 A T H E S I S SUBMITTED I N P A R T I A L FULFILL16NT O F T H E R E Q U I R E M E N T S F O E T H E D E G R E E O F MASTER O F A R T S ia tho DEPARTMENT O F ZOOLOGY We accept this thesis as confonaing to the standard required frea candidates for the degree of MASTER O F A R T S Members of th® Department of Zoology T H E UNIVERSITI O F BRITISH GOXWIA A p r i l , 1956 I P A study of plankton communities in th© Strait of Georgia was undertaken in order to determine qualitatively and quantitatively the distribution in time aad space of both aooplankton and phytoplankton. In order to gain some picture of the seasonal, variations in the plankton communities two cruises wer® made in the Strait* one in June, 1955* and the other in Mov@*@r* 1955 • 165 plankton collections were taken* A complete count of zooplankton organisms was made in 5cc• of ©ash sample and the number of diatoms cells >per liter was tabulated. Copepods and diatoms were analysed to speciesj other groups to class or genera* Surface temperatures were taken* the physical and chemical data, used to account for th© biological distributions wer© obtained7 largely from ooeanographic data already available for the area. Th© correlation of these data have resulted in a number of conclusions concerning the distribution of plankton in the Strait of Georgia. The ©hief factor affecting th© general distribution of plankton in the Strait of Georgia is the salinity gradient. The inflow of fresh water from the Fraser River forms zones of varying properties, and leads to the development of different plankton caamunities. The extent to which physical and chemical factors may determine the presence or absence of certain organisms from the acnes described is discussed* - i i i - mm OF Qowwfg PA01 i . imoDUcnoH i I I . DXS&JBtraSGtf QT PHYSICAL A » CHEMICAL PlOmTIES OF THE wAms I N T H S snux? OF G E O S G I A 5 a* Salinity 5 b. Teiaperataro . . . . . . . . . . . . . . . . . 7 III. MflSIALS AM) METHODS 11 a. Area covered . . * • • • . • • • • • II b. Sampling methods . . . . . . . . . . . . . . . 16 1* Vertical hauls . . . . . . . . . . 16 2. Hardy Recorder tows 17 e. Laboratory methods 18 I V . RE3ULTS • 1 9 Composition of the plankton 19 1. Zeoplankton taken in the suramer cruise, June 8-16, 1955 . . . . . . 19 2. Phyteplanktori taken in th© master cruise, Jane 3-16, 1955 . . . . . . 23 3» Zooplaakton and phytoplaakton taken in the f a l l ©raise, November 7-ll» 1955 • * • 28 ?. DISCUSSION . . . . . . . . . . . . 32 a. Abundance ©f plankton in the Strait of Georgia, 32 1* Abundance of gooplanktou in the sower ©raise* Jvm 8-16, 1955 » • |2 2 . Abundance of pliyf^plankten in the susener cruise, Jtsae 0-16, 1955 . . . 37 3« Abund&ne© of zooplankton and phyto- plaiikfcoa in the f a l l cruise* l©ir©a3»r 7~1©# 1955 . . . . . . . . 42 b. Distribution of the plankton 46 1 . Vertical distribution • • • • • • • 46 2. Horizontal distribution at constant depth 47 e. Some charaeteriatics of the nest important groups . . . . . . . . . . . . • . 53 1. Copepods . . . . . . . . . . . . . 53 -» i v - TABfiB Of OQWaKft (e«melud©d) PAGE PseudoealaRua iKinutog 54 Aoartia * • * • * • « # • • • • » • 55 Qjthcam • • . . » . . » . . . . » • 5® Calamas « « » * « » * « • • « « « • * 59 Metrldla • • • » « « • » * • • » • 60 laijalaaai® Iwrwdi. . . . . . . . . . 61 C@ntropag@8 moimu'rlalxi . . . . . . 62 Other species ©f restricted distributieii Offi^auga: eonifera • • • • • • • • • 64 800^^.1^.6®!!^' ifteai* . . « « • 64 Microcalanus pusHliaa . * • • • • 65 Euehaeta .laponica . . . . . . . . 65 Faraealanus parrus . . . . . . . 66 ©^r^ an^ jg discaudatus . . . . . . 66 Epllabldoeera aiaphitrites . . . • 66 <M4itt>. m^rnm and ghirMitts tenuispinuB . . 66 - 2. Appendicularlsns »«• « • » « » • * 67 $• Euphausids • • • • • 69 4* Cliaetogtiaths . . • • • • » . . • • . 74 5 » Amphlpods . . * . . . . . . * . . « 75 6. Gastropods • • • • • • • • 76 ?. Ostracods and Cladocerans . * . # • 77 #• Larvae 79 9» OistosB® » • « • • • • • • • • • • • S3 Skeletoneiaa . . . . . . . . . . . 81 Thalaaaioaira 81 §h®^mm®ft • . » • • * » • * # # 84 .MitgasMa 84 Khjgoaelenia . . . . . . . . . . 86 Biddulphia «.*#*»•»**•» 87 thalassimem . . . . . . . . . . V I . CC*ICUJ3XGMS . . . . f2 V I I . nfSfwcis . . . . . . . . . . . . . . . . . . . . . . . . 96 i*l^ y .PJT •.^ '^^ ffiSS fwm PA® 1. Strait of Georgia showing sections aad© with the Hardy Recorder * . . . . 2 a. Seasonal, variations in Fraser River discharge at Hope, B.O.* 1950 (after Waldletatk, 1952) 6 3. Surface temperatures, June 8 - 16, 1955 . . . . . . . . . & 4. Surface temperatures, November 7 - 11, 1955 10 5. Location of Stations, June 8 - 16, 1955 . . . . . . . . . 12 6. location ©f Statical* Novesaber 7 - 11, 1955 » • 13 7. Diagram of plankton net used in the survey . . . . . . . . 14 0. Diagram of Hardy Recorder in sectional view (after Hardy, 1939) . . . . . . . . . . . . . . 15 f. Zooplaaktm abundance from earfaoe to depths ©f 10, 20* and 50 asters, June 8 - 16, 1955 33 10. Fhytoplanktw abun&aae® from surfaee t© depths ©f 10, 20* and 50 meters* June S - 16, 1955 • 39 11. Salinity at two yard® depth in the Strait of Georgia t r m synoptic sunrsy* June 1950 (after Wsldiotek, 1952) . . 40 12. 2©oplankt« abundanee trm swfae© to depths of 10, 20* and 50 asters, November 7 *- 10, 1955 45 13* Histograss showing the ©oeurrenee of ©opepeds at different depths, June S - 16, 1955 . 48 14* Histograms showing th© variations of g@eplankt©n and phytoplanktm at constant depths* June S - 16* 1955 * • • 50 - id LI3T OF FIGURES (concluded) FIGURE PAGE 15* Histograms showing the variations of aooplankte n at constant depths, November 7 - 10, 1955 52 16. NuRfeewof Aeartia l,m£bM®&9 found in the upper 10 aieters (a) and 20 asters (b) plotted against surfaoe temperatures, June 8 - 16, 1955 * * * * 57 17* Numbers of Qilcopleura epp.found in the upper 10 meters plotted against surface temperatures, June 8 - 16, 1955* • • 63 10. Abundance of Jj^tpneata, f^tatuaat 10 feet, June a - 16, 1955 32 19. Abundance af S&Q&filftf4*ft @pp* at 10 feet, June a - 16, 1955 . . . * S3 20. Abundant of Ohaetoaeros @pg. at 10 feet, June & - 16, 1955 55 21. Percentage distribution of the four most predominant phyto- plankt«a» geaera along the Hardy Resold er cross-sections, •tee & - 16, 1955 89 22. total phytopLanlcton abundance at 10 feet, June $ - 16, 1955 90 - v l l - LIST OF TABUS TA§X$ FAGE I. Percentages, by numbers, of ©even constituents of th© aooplankton, June $ - lo, 1955 24 II* Estimated numbers of zooplankton and volumes of phyto- plankton collected, June 8 - 16, 1955 • 34 III. Estimated numbers of zooplanktea and volumes of phyto- plankbon oolleeted, Noves&er 7 - H» 1955 43 If. Averago aontaly distribution of Aoart&a IcistgireB^s la 1927 - 192* and 1920 - If29 (after Johnson, 1932). . . . . 56 7. Murabers of juvenile and adult SentropMos y»rrlehl taken at I©-©, 20-0, 50-0* 100-0* aad 150*0 meters, June 8 - 16* 1955 • • 63 ¥1. Larval stages* by atatoera* of eaphaasids, June 8 * 16* 1955 71 VII. Concentrations of adult euphausids taken at different depths, based on a total count of the animals In each sample, Novenber 8-11* 1955 . . . . . . . . . . . . . . . 73 VIII. eoneentr&tions of adult chaetognaths, taken at different depths, based ©a a total count of the animals in each sasnple* lovsMber 8 - 11, 1?5S . . 75 IX. ©fflaeeatratiens of adult a^phlpods* t aten at different depths, based on a total count ©f the animals ia each 76 sawple, Mmmfaar $ - H# 1955 » * * » . . * . » . . • . . . X. fertioal distribution of gastropod larvae and ©onoeatys- tions at each depth, June 3 - 16, 1955 # * • * 77 XI. Average nwsfcers of ©©pepod, baraaele, and orab larva® caught in moh haul, Jun® # - 16, 1955 . . . . . . . . . . 79 - viii The writer wishes to express his sincere thanks to the following? Th© National Research Cornell for providing financial assistance during the period ©f this study in the form of a Suamer Supplement during th© susaaer of 1955 and a Bursary during the Academic Term 1955-56} to Dr« B.F# Seagel, Assistant Professor in th© Bepartiaents of goolo^- and Botany, for suggesting the problem, for arranging the cruises, for assisting throughout the entire progress of the work and preparation of the manuscripts Dr. M. Waldichuk, for the use of extensive unpublished data on the physical and chemical oceanography of the Strait of Georgiaj Dr. J.P. fully for the as© of ©ceanographio equipTOnt) Drs. W.S. Hoar, J . Sanjean, C*G. Lindsey, and G.L. Piekard, for the use of special aicrosoopic and drafting equipment j th© master and mm of the C.N.A.7. «Ihk0li,, for their assistance and co-operationi and fellow students for their help and numerous suggestions throughout the year. The Strait of Georgia ©couples a position of considerable inter est for the study of plankton because within its limits l t presents an unusual complexity of conditions which differ greatly from summer t© winter. In summer the fresh water from the Fraser River flows into the Strait and spreads over the surface in cloud-like distribution, mixing with the saline water to form a brackish upper layer which is well differentiated from the more saline, homogeneous waters under neath. In winter the river discharge diminishes and most of the water in th© Strait reaches an homogeneous state. Th© Strait of Georgia itself is located between the British Columbia Mainland and Vancouver Island, and extends from Latitude 48* 50• fl. to Latitude 50• OO' N. (Fig. 1). It is 120 nautical miles lcng and l i nautical miles wide. It has an average area of 2000 square nautical miles and a maximum depth of 230 fathoms. The weather is generally similar over the entire area of the Strait. The precipitation is high in the fall and winter, and the summers are generally sunny and warm. Air temperatures seldom go below freezing. In winter they average 2* C and may go as high as 10• C- In summer they average 18® C. In accordance with the complexity of conditions, the distribution of speeies Is intricate and their relative abundance fluctuates widely £rm place t© place and from time to time. It has been already pointed out by Fraser (1918), that certain free-moving shore forms which occur constantly throughout the surface at Friday Harbor disappear from near the surface at Departure Bay early in sumer, making the question of migration a matter of importance. Cameron and Moune© (1922) found that some species exhibit a difference in morphological character and rate of growth which can. be traced to different physical and chemical conditions, and shewed that th© Fraser liver was responsible for most of the conditions peculiar to these waters. Lucas and Hutchinson (192?) cams to the conclusion that diatom optima exist where th© Fraser River water and th® sea water are mixed. They suggested the contribution of the Fraser i s in the form of mineral salts containing nitrogen, phos phorous, and silica. They also stressed the important tide-diatom re lationship; north of the Fraser the optimum i s at the flow* south of the Fraser i t i s at the ebb. Hutchinson (1923) showed that the richness of the plankton flora was largely dependent on the Fraser as a source of siHea and also upon the conditions which conserve this material. Hutchinson, Lucas and MoPhail (1929) dealt with th© seasonal variations in the chemical and physical properties of the Strait of Georgia in re lation to phytoplankton. Hutchinson and Lucas (1931) studied the extent of tha Fraser River's effect on temperature, salinity, currents and fish food. Again i t was found that the amount of phytoplankton is greatest at the regions of water mixing, fully and Bodlmead (1954) also discuss diatom distribution in terms of dissolved oxygen, pH and dissolved nutrients. They attribute the high concentrations of dissolved phos phates to the intruding ocean waters, and the high concentrations of dissolved silicates to the Fraser River waters. They suggest that the supply Of dissolved nitrates i s the limiting factor in phytoplaaktoa growth. Some preliminary work has been carried out by Gampbell (1929) on the distribution of definite classes of marine organisms in the Strait of Georgia. In this thesis an attempt is made to evaluate qualitatively and quantitatively the organisms responsible for the abundance of both phytoplanktea and sooplankton and to assess the physical and ohemloal factors affecting their distribution. - 5 - P- D3y«>3OTiqi OF PRT3;0AL AMD CHpiOAL PROPERTIES OF TIE WAfERS IN TIE STRAIT OF GEORGIA The range of salinities existing in the surface waters of th® Strait of Georgia varies from 1 fU at the Fraser River estuary t© 25 at the northern and southern extremities (Waldichuk, 1955)• The Fraser River discharge dominate® the general oceanography. The fresh water flowing into the Strait from the River spreads over the surface, mixes with the saline water, and forms an upper, brackish silty layer re ferred to as the "upper zone" (Tully and Dodimead, 1954)• Low salinity cells exist in the southern Strait, and consistent gradients of salin ity appear where the low salinity surface water mixes with the higher salinity waters brought up to th© surface by tidal action. Surface salinities are lowest over the eastern portion of the Strait along the mainland. The greatest variations occur in the suwaer close to the mouth of the Fraser. This corresponds t© the peak discharge of fresh water (Fig. 2). This peak discharge is the result of snow and ice melting in the upper reaches of the River. Small rivers entering at ether points in the Strait contribute about 16% of the total fresh water* The upper sone ie about 30 feet deep at the mouth of the Fraser and deepens to 00 or 90 feet as i t fans out over the Strait (Waldlohuk, 1952). Isolated cells of water ©f varying properties ar® found at th© surface and their position depends on the Fraser River discharge, the tidal cycle, and the wind velocity. - 6 - 500 JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. 1980 Fig.2. Seasonal variations in Fraser River discharge at Hope, B.C., 1950 (after Waldichuk, 1952). Below th© upper sone there la a layer of fairly homogeneous salin ity, referred to as the "lower zone", and between the upper sons and the lower zona, there is a transition layer, referred to ae the "boun dary sone" (Tally and Dodlaead, 1954) • This boundary zone is character ised by a steep gradient of salinities* In November the upper sone of low salinity is confined to the vicinity of the Fraser and averages 4 meters in depth (Tully, 1954)• Ho distinct upper sone is traceable in the northern part of the Strait at this tiro because of the low runoff of the Fraser Elver* b. temperature Surface temperatures in the Strait of Georgia for June, 1955, are given In Figure 3» The southern Strait exhibits the lowest temperature (12*4° C). This Is produced by tidal currents in the channels mixing ©old, deep water with th® surface water (Waldichuk, 1953)* The surface water is ©old near the Fraser River estuary (12.8* C at Station 12) because the inflowing fresh water is colder than the water in the Strait. The highest temperature (15.8* C) is recorded off Gabriola Island. Generally surface temperatures are lower in the eastern portion of the Strait along the mainland and higher In the western portion of the Strait as a result of insolation. The surface gradient over the whole area was only 3 »4* G in June, 1955• The depth of heating corresponds to the upper mm which is generally less than 10 rasters deep in summer (Tully and Dodiaead* 1954) * Below a depth of 60 meters ths waters are fairly stable throughout the year, with temperatures around 7* C The "boundary layer" is characterised by a steep gradient of temperatures. F i g . 3. Surface temperatures, June 8 - 16, 1955. . - 9 - Surfaee temperatures in Hovember (fig* 4) are fairly uniform over th© central part of th® Strait. The northern waters, which are in the sone of minimal change, ar© a little warmer with a difference of temperature over the Strait of only 0.9* G (ranging froa C to 9*4* 0.) * fhe effect of th© Fraser liver is therefore less marked In November, loss of heat to th® atmosphere takes place. B» Movsmber strong winds mix the waters to great depths so that th© deep waters are warmed and an isothermal state is reached (Tully and Dodlaead, 1954) • - l i - m. MATERIALS AND METHODS The data presented are based on 165 plankton collections taken in the Strait of Georgia during two cruises - on® in early summer, from June 0 to 16* 1955, and one in th® f a l l , from November 7 to 11, 1955* The first cruise covered 30 stations distributed throughout the Strait from the San Juan Islands to the northern end of Texada Island* How ever, as a result of bad weather conditions at the time of the f a l l cruise, i t was possible t© reoceupy only 26 of the 38 stations established on the earlier cruise. The stations occupied are distrib uted between latitudes 48* 48» » - 49* 40» N and longitudes 122* 50» W - 124* 45' W (Figs. 5 and 6). At a l l but three stations two vertical hauls* using a plankton net (Fig. 7)* were mad®. Th® first haul was always taken in one of three shallower depths (froa 10, 20* or 50 meters to the surface) to prevent contaminating the net with deeper plankton species and a deeper haul was taken through strata varying froa 50 to 250 meters to the surface. Surface temperatures were obtained at a l l stations at which plankton samples were taken. Compass bearings were taken at the start of each haul. Records ©f scale depth* wind valoeity, barometer readings and cloud coverage were kept* A few stations were omitted during the two cruises in order to give maximum coverage of the Strait. In addition to the vertical hauls, horizontal sampling was carried out with the Hardy Recorder (Fig. 8) during the first cruise. The ctojeet in using th® Hardy Recorder was to determine th® horizontal - 14 - OCEANOGRAPHIC CABLE b) ROPES ( 3/8" diom.) RING ( 2 0 " diom.) MESH SIZE 25 XXX METAL CLIP PLANKTON JAR 500 cc. a) STRING WEIGHT 50 lbs. Fig.7. Diagram of plankton net used i n the survey. - 15--16 - changes in the major constituents of the plankton over the areas Investigated between the stations at which the vertical hauls were made* b» Sampling Methods In order to obtain some indication of the concentration of plankton at different depths and to trace the vertical and horizontal boundaries of distribution of the main constituents of both phyto- plankton and sooplankton, a number of sampling methods were employed* To determine the vertical limits of distribution of th© main constituents a plankton net was used (Fig. 7). The net measures 20 inohes in diameter at the mouth, 60 inches in length, and 4 inches in diameter at the cod-end. A jar having a volume of 500 c c is held tightly at the small opening by a metal slip. A string (7a) joins the metal clip to a 50-pound lead weight to keep th® net from turning in side out when lowering. The weight i s suspended from the lower end of three ropes (7b) • These ropes, which pass alongside the net, are tied around the metal ring forming the mouth of the net, and are attached above the mouth of the net to the oceanographic cable. The net is made of bolting silk Ho. 25 xxx. fh© same net was used throughout both cruises. I' W i c a l Haulg the shipboard procedure followed upon reaching a station involved first reversing the engta® to bring the vessel to a complete stop. Some leeward motion of the ship was encountered while the sampling w being carried on, but this minor drift was disregarded. 17 - AH stapling was performed from the starboard side of the after deck, fhe ship was provided with a powered winch and a meter block. fhe net was lowered slowly at & uniform speed and. upon reaching the desired depth i t was also retrieved at a slew* uniform speed. When the net reached the surface i t was lifted out of the water and while s t i l l suspended from the oceanographic boom i t was washed down with three or four buckets of sea water, fhe plankton jar was then detached and the sample was transferred to a glass jar. The organisms clogging the net were washed free with a wash-bottle. Some formalin at % concentration was then added to the sample and a label was placed in the jar* U,Pttlt9W***FJ<m The instrument consists ©f two elements, th© external torpedo- shape body weighing several hundred pounds and the internal removable mechaniam. The body is fitted with two ailerons and on® ©levator, s© that when it is towed i t will dive and maintain itself at uniform depth. The depth is determined by th© amount of cable played out. During the tow i t is continuously sampling by filtering plankton through silk from a roll which unwinds slowly across a water tunnel by th® action of a propeller turned by the passing water (Fig. S). Wen launching the Recorder the ship was stopped and tha instrument was slowly lifted over the rail. This was done by using the main boom of the ship to l i f t th© instrument and at th® same time swing i t clear R ©f the stern while i t was being lowered. When th® recorder touched the water the block and tackle was detached, and the towing cable played - 18 - out te a mark placed on it at a point calculated to give a sampling depth oi" ten feet, fhe towing epeed used varied from 8 1/4 to 8 l/2 knots, depending on the direction of th® tide* At launching and at hauling the position and time were recorded* When the haul was com pleted ths recorder was hoisted inboard and the used section of silk was removed. The silk was then transferred to a glass Jar and formalin at % concentration was added. All the zooplankton samples were analysed in the laboratory with a binocular microscope using a 40 X magnification, and all the phyto- plankton species were identified with a compound microscope using 100 X magnification* fhe following treatment was used in analysing the samplest 1) the plankton sample was well shaken and 5 co* were removed with a pipette having a length of 30 em. and a diameter of 8 mm. A complete count of the aooplankton in the 5 cc* sample was made and tabulated as follows! all copepods to species and sexj nauplii, meta- naupiil, oalyptopls, furcilia, cyrtopia, and adult stages of euphausidsi all other major taxonoaic groups including appendlcularians, chsetognaths, amphipods, gastropods, ostraoods, oladocerans, eggs, and larvae. 2) The qualitative analysis of the phytoplankton was made by placing a few drops of the original sample in a ruled chamber and scanning the whole field. After the entire chamber had been examined a new sample was drawn and from this chamber, which has a volume of 166 cubic millimeters, counts were made for each species * When the - 19 - quantities of pbytoplankton sells were great l/6 of the volume was counted, when they wer® small the number of cells i n 166 cubic m i l l i  meters was counted* 3) In addition to the normal procedure outlined i n section 1) and 2) a total count was made of a l l adult euphausids, chaetognatha and amphipods i n each sample taken on the November cruise* 4) The s i l k taken from the Hardy Recorder was cut into sections each of which represents a horizontal haul over a distance of three te five miles* The plankton was then removed from each section. The large organisms were removed by hand, the smaller ones with a razor blade, and transferred to 100 c c of water* A total count of a l l the zooplankton was made from each section of s i l k * The pbytoplankton was analysed and counted as outlined i n section 2). ffi* assets, Jfr. eo^®aiti.on of the P^aktoa 1) Zooplaakten taken i n th© suraaer cruise, June & - 16, 1955* Some 34 species of copepods i n the following three sub-orders were takens Sub-order GAUMQWA Aoartia clausi Giesbrecht £• lon^remis (Iceberg) £• ,ffinaaricMeius (Qunnerua) Candacia eolumbiae Cajatjbell BinTniTTiigBffli i r i ^ f f l ' T w M r j T * f i ? i fif^r^fffftt^B pqirwaiyi Johnson ^Mrldittfl ijaattisptaas gars Di&ptcsaua sp* Westwood . M&ifflfom m*4totom (McMurrioh) Buehaeta iaponiea Marukawa te^ffl^^ MmfaMW- (H«r*plafc) j * johanaeni Wllley W i l W«w Giesbrecht If* lueens Boeok ^ , 4 » (Claus) ^oleoithrlce^ minor (Brady) HWffi&S d^ soau^ attts (Thompson and Soott) 9ub~order OltaoPOIM ASWJMft J2^g Campbell MeHarrish m ^ S i hel^ o^ andioa Claus ^Wto Baird &S8Sft «mU«B. ©iesbreeht a - Sub^der BARffACTICQlPA, •^WffW ffi^WWt Campbell ^pactigus, fl^fflpftt Mr®** Idva furoata (Baird) A few unidentified but par® species of a number of genera were met in the samples but wore not identified because of taxonomic difficulties. Several phyla were represented by many genera but not attempt was made to determine these beyond major groups. The following 26 groups were analysed in this way: Amphipods Annelids Appeadieularl&ns Barnacles t naupllus stage eypris stag© Chaetognaths Gladoeerans Copepods t naupllus stage meta naupllus stage Crabs i zoea stag® metasoea stage Clam larvae (early) Bgg» - aa Buphausids » nauplius stag® metanauplius stage calyptopls stage furoilia stag® ©yrt®pl& stag® Fish larvae Gastropods Melethttrians Hysis Ostraeods Coelenterat® pianola Brittle star pluteus polyehaet© larva© fteropod larva© Shrimp larva® Slphmophores Snail jjttiaaB^ fintinnida© - observed bat not analysed Unidentified triangular egg ©as® Protozoans were also found ia a few samples* The mesh size of th® net too eoarse to retain these organisms in any quantity and a© attempt made to study their distribution* A few radiolarians were observed, but wer® not identified. Among the protozoans observed were* 23 Smfam I f f iSS (Ehranberg) D^ <>ffi¥4,s £a£tat& Stein PA^JWHf, WfflflW v*r« .fWri^tt Lemraeraann Genyavaax sisinifera (Olapared® aad Laehmann) Percentages, by numbers, of seven constituents of the aooplankton are given in fable I. In almost all samples copepods were the most abundant of all constituents* the appendiculazlans (O^kopleura spp.) were second in abundance* followed by euphausids, eggs* chaetognaths* gastropods an! amphipods* Next, but not included in this table, were the larval stages of barnacle, crab, ostrocods, cladocerans, hydro- medusa®, annelids, polychaete larvae, fish larva© and other, less frequent forms* At a few stations there occurred large numbers o f other specific group®, such as Siphonophores and Llttoriaa, but in each case these were local populations and did not contribute to any extent to the overall distribution. 2) Phytoplaalcfeon taken ia th® stammer ends®, June S - 1 6 , 1 9 5 5 * Forty-five speeies of diatoms were found. Th® following list is not complete and in a few cases the identification to species is some what uncertain. Some slight differences of opinion on the taxonomy ©f certain specie® are found in th® literatur© (draa and Angst, 1931 and @upp» 1943) which render th® identification of certain sp®el#s, such as in the genus Chaetoceros, difficult. Nevertheless, i t is possible to compare the relative abundance of most species in tha area with th® data available. TABUS 1 Percentages, by numbers* of seven constituents of the zooplankton, June 8 - 16, 1953. Stn» No. Depth (a) Eggs $ Cope-r Gasiro-! pods * Anmhl«•» O'haeto-gnaths % auslds * pods 16 I 1© 12 45 36 1 1 1 . 1 50 15 68 12 1 1 2 10 7 30 46 - 1 1 4 2 80 20 48 20 3 3 4 10 10 20 58 - 1 2 k 100 10 61 17 4 *> 3 5 20 3 50 23 2 2 5 200 4 32 5 4 - 1 6 50 5 29 32 1 7 7 10 30 33 12 1 1 1 3 7 90 25 69 2 1 — 8 50 6 67 4 4 12 8 110 3 76 7 4 5 10 10 27 U 55 -10 150 XL 51 26 3 — 2 11 10 mm 69 12 - „ 14 11 100 4 65 14 1 1 9 12 10 - 64 10 - 10 12 50 12 60 15 - _ 1 2 33 10 - 88 7 13 50 6 72 8 - 2 „ 3 14 20 5 22 64 - - 1 2 14 aoo 3 63 24 3 1 2 11 10 5 27 58 I - 2 1 15 im 3 58 24 6 1 2 16 10 - 87 4 - 1 7 16 mo 80 4 3 1 9 17 20 5 79 6 1 3 3 1? 150 4 78 7 4 1 4 IS is — 59 8 1 1 1 22 18 150 5 73 2 12 «. 3 19 50 3 69 1© - 1 5 1 19 200 4 77 2 Z 2 6 20 20 17 54 15 » - 4 2© 250 8 71 5 ". 2 2 - 4 25 TABLE I (continued) Mo. (») Oastro- Amphi- pods pods CSsto^T gnaths auslds 9 — . ,„ •, 7> , , ,„ 2 2L 11 8 - 1 13 3? - - * 6 23 5 1 2 3 1 - 1 a 2 - • *» 13 » •» - 2 9 1 1 1 3 8 • 1 2 5 - — 1 2 4 3 1 5 5 2 - 1 6 3 2 I 12 5 1 1 3 2 1 2 2 1 3 1 - 3 1 1 12 *» 1 1 4 1 - 1 27 1 3 1 4 1 8 1 4 3 « 5 1 1 2 3 * 11 11 17 3 1 4 1 5 '11 - - 3 8 6 3 2 13 11 5 - 1 2 5 6 - «•> 2 2? 1 1 1 8 2 3 - 20 5 4 - - 5 2 5 - - 6 2 — — — 3 4 « 6 5 2 3 1 12 2 9 27 5 5 « - 10 4 5 9 f - 2 7 12 - 2 33 1 1 1 3 7 . 5 3 1 5 24 2 21 21 22 22 23 23 24 24 25 .25 25 25 25 26- 26 27 27 28 28 2f 2f 30 30 31 31 32 32 33 33 34 34 35 36 3? 37 38 38 41 41 43 20 150 10 100 10 100 20 50 10 20 50 100 15© 20 150 20 50 20 23© 50 150 10 150 10 100 20 100 10 200 50 ^ 100 10 100 50 100 20 100 10 200 50 6 3 17 2 49 17 23 18 35 17 13' 7 8 1 2 1 7 4 3 9 2 2 9 3 9 4 1 1 10 2 7 4 5 8 38 82 81 94 82 55 # 71 74 73 71 23 56 26 The following diatoms were identified* A^terfonolla japonjoa Cleve iaoteriastram delieatigtam Cleve M^f>*J4 (Lyngbye) Brebisson and Godey !• iaSSiS Ehrsnberg B. lengieraris Qrevill® CMhaetoo®ros afflnis Laud.r £» brevis Sohttt £• soneaviaomis Mangin £• oontrietus Gran £• g^vo^utfg Castraoan© £. etigvisettts ciev© £ • » M 3 1 » Cleve I* d«9QiPiens Gl@v® £• ^ Mww Ehr®nb®rg £• laoin®stts Sehtttt £* i g w w t e a i Gy^w C. radieans Schfttt I* Sieve £• teres Cleve £• vanbeareki Gran ABESlLteai Jteg&Ste Jensen .g^ einodisetis jaf^ri.o.us, Ehrenberg C. waileaij Gran and Angst ft^ff » * i f t * ^ t t » (West) Grunow 27 ffMHBrt* ftO^ W^ff. IHrenkerg Frai&laria eretonensis Kltton £* »t,rjatula lyngby© flaMifrtfrFft ffi&M (l#ngby©) Ktttzing |^ Bfc«eylind«tUf da^ oua. Clove HiSSSIS .pwtf,M<n4f, (Mller) Agardh E* ytiMfc* (Ehrenberg) Ktttsing Mavleula sp. Bory Nitasohla sp. Hasssll flmee@±mm sp. Smith BhigoseleaJa dolioatula Cleve £* faebotata forma eemletxLna (Hansen) Span &• styliforaie Brightwell gfeleteasaa (Creville) Clev© t^fphanofflKis, ?rt«po^ Sa Gran aad lend© fhala^ione^ nltMshioidss Grunow fhalaasioslra c^ ndsnisata Clev® £« deelpiena, (Grunow) J^ rgsnaen ixtgdsnskioXdii Clew Jhalass^thgias frausnfeldil Qranow The dominant filamentous diatom genera found in June were ^eletonejj, ^ haetooeros, Th^aasloslra, B idd^M^, and Hitgsehia. fhe length of the filaments eould not fee approximated. Th© formalin solution used made the filaments very brittle and most of them broke apart when th® samples were shaken. - 28 - 3} Zooplankt on and phytoplankton taken in the f a l l cruise, November 7 - 11, 1955. Some 35 speeies of copepods wore present in varying abundance in the samples taken in the summer, whereas only 21 species were present in November, and in very much smaller quantities in th® latter instance. Some species, such as Calanus tonsus, Eucalanus JbJSgJ4, and Cenfrropafi®s momurrichi, which wer© very abundant in June, could net be found in the samples in November, although the same depth® wer© sampled* Deeper forms, such as CeatroiaaBtlluB porcellu®, Harpaetious unireml®, and Idara fwoata, could not b® found in November, even though th® water, at such depths, is relatively unifoan in physical and chemical characteristics throughout th® year* One species, Aatideus armatus, was found in th® f a l l , but was not observed in June. fhe 21 specie® of eopopods in th@ following two sub-orders were takent Sub-order CALANOTJJA Aearl^a clausi Gi®»br@®ht totofrm. mtsm tee*®® Calapxa, fflnm^h^ous (Gunaerus) fiff^ftS^ft Campbell P # # ^ amphitntes (Mcterieh) M*mM JsmZm Marukawa menfatm. MwW®,®, ciordquist) Gaidiua pungons Gi®sbr©eht - 29 - mepoeiaaaus m s i l l u s Sars Pssudeoalanuji jg|Jiut|||| (Kr^yer) gcolecithrioella minor (Brady) XWtomt (Hams*** aad Scott) jjub-ordsr ($m?pm hW*mm i^m Campbell Serrcasua a f f i n i s McMurrlch ftWMft Giesbrecht Th© percentage of adult and immature individuals was found to remain quite constant i n June and i n November. Fifty-three percent of the summer catch was made up of adult specimens* as compared with fifty-two pereent i n the autumn. Many of the species found i n autumn* such as galanus finaarchieus* were therefore actively reproducing and not just saarvlving. fhe same i s true for several ©ther groups because immature specimens of amphipods* ©l&docera&s* barnacles* and ©stracod® were found i n the samples taken i n November* In addition to copepods* th® main constituents of th© sooplaakton i n November were* - 30 - Appendlcularlans Cephalopoda (egg ease) Ghastognaths Cladocerana Barnacles * cypris stage Slam larva© (early) Echlnoderras (archenterie sack) Sggs luph&usids Gastropods Holothurians Hydromedusas Sattplil Copepods s naupllus stage Ostraeods Polychaete larvae Slpb®»opheres Unidentified triangular egg case Catches of chaetognath® and ©uphauslds were made up entirely of adult specimens i n November* The unidentified egg ease was th© next most abundant constituent of the sooplasktoB after the copepods* Next came the euphausids* chaetogaaths, amphipods, gastropods, jOlkj- blsura, ostraeods, and hydrowdusa®. Th® other representatives wore never abundant• 31 Only two species of diatoms obtained in November samples were significant. ftfcmta^^M ^ PMmsm $m®&ms£& were found in relatively large numbers. Ther© was a dearth of all other species, a fsw soils of .Chastens,. sMM&> ^?osolenia semispina, aad Nffigschla sp. were also encountered. Out of fifty-two samples, only thirteen gave values of more than 1 cell per liter and the maximum frequency never exceeded 10 cells per liter. Mo proto- scans were seen in the plankton samples taken in November* -32- V* PI30US3IOM a. Abundance <*f jg^kton in the Strait of Gsorgla 1) Abundance of zooplankton in th© summer cruise. June 8 - 16, 1955« To provide a basis for comparison ©f the total catch at any one locality, all quantities obtained from the 5 ce. samples quantitatively analysed wr© transformed into values based on a standard volume of one cubic meter. This was done by dividing the number of aooplankton per sample by th© volume of water filtered. Since no device was used to record the amount of water filtered, it is assumed that th® net was fishing vertically and no spilling occurred. With this assumption the number of cubic meters of water strained at each depth was then calculated. This method of calculation cannot give a complete eval uation of th® aooplankton distribution with depth, but it points out with a reasonable degree of accuracy th® areas of high, average, and low concentrations. Based on the quantitative ©valuation of the zooplankton obtained ia the above manner three centers of different concentrations (Fig. 9s Tabl® II) can be recognized and associated with th© physical and chemical characteristics of the waters in the Strait of Georgia. A) an area of high concentration at Station® 10, 11, 12, 1 3 , 15, 21, and 22, with warm surface temperatures (ranging from 13»5^C to 14«7^ C) and strong mixing ©f water masses. B) an area of intarmediate concentration at Stations 1 6 , 1 7 , 1 9 , 20, 23, 24, 25, and 32, with colder surface temperatures (ranging from 12 .B% to 13.7*0) and little mixing of water masses. F i g . 9. Zooplankton abundance from surface to depths of 10, 20, and 50 meters, June - 34 - II 1 St r fojj f i lllililllli^PliillllBgs I3 te 1 1 i i . . . . . . . . . . | . . . 2B 3* Se Ss 3E 35 SB » * » gi » » ¥ h* k* 8* &§* Ss ^ B Ss 5* MN -S1 S\ U N U N * 8 ' * 8 © $ i i i i 4 i i i 5 s s - 35 - I te I f ||HiiH|H||§lg|II|i|ipgi 9 ilBllllllIIilliiBBIlllilill a s » a s a s s | " ' | | " | " I'M I'"- fe a I § a fe & h" »' » " R° R* » " J " S " " 5" 3° S S S S S 3 *S S *E S S S » • » « « • « « « • * v TABLE H ( Stn. Io. Position latitude loagit' ado Sat® Tine PST 2d 49° 23• 10* I 123* 54' 15" ¥ 14 1718 28 n w 1728 29 49* 22» 10« I 124* 01' 30* I June 15 1538 29 a s 1548 3© 49® 26' 45" I 123* 54' 15" V June 14 1627 30 ft 8 1637 31 49* 19• 45" » 123* 51* 15* 1 June 15 1653 31 • 1701 32 49* 15• 15* I 123* 49' 30s W 1751 32 a 1800 33 49* 23' 30" I 124* 16' 00* w 0619 33 n » 0629 34 49* 26« 20* I 124* 23* 00« w tl 0725 34 » a 0738 35 49* 29' 30» H 124° 30* 15 s W H 0827 35 « a 0835 36 49* 33« 15" * 124* 27« 00" w a 0913 36 « a 0921 3? 49® 36' CC» S 124* 33' 45* ¥ » 1008 37 « H m t 38 49* 40* 00« 1 124* 45' oo» w ff 1124 3B w a 1138 41 49* 15' 40" X 123* 42« 54* w June 8 2320 41 a 56» « * 1345 43 49*13' 54* 1 123* 50« Juno 9 1430 ) Depth retrained 20 4.06 1054 20 23© 46.69 165 5 50 10.15 ©43 9286 150 15.48 344 88 10 2.03 1460 12 150 I5.4S 1147 2f 10 2.03 5282 2605 100 20*29 742 1009 20 4.06 4666 1246 100 20.29 1144 528 10 2.03 2456 2553 200 40.58 677 78 50 10.15 3^ 90 1305 150 15-48 2191 1661 20 4.06 11070 5592 100 20.29 3225 774 10 2.03 3360 44351 100 20.29 1320 594 50 10.15 3880 1328 100 20.2? 2195 538 20 4*06 5141 7650 100 20.29 3072 178f 10 2.03 2850 2293 200 40.58 890 313 50 10.15 722 777 1 ot 1 3? S) aa area of law concentration at Stations 18, 26, 27, 20, 29, 30, and 31, with still colder surface temperatures (ranging from 12.4*0 to 13.6*$) and little mixing of water masses. The catches mad® in the tows between 50 «®t«rs and the surfao® were more characteristic of the Strait of Georgia because they included populations inhabiting both th® Hupp®r zone" and th® uppermost stratum of the homogeneous "lower zone". Th® catches proved to be fairly uniform from station to station, as far as th® predominant species wer® concerned, and thus copepods were, in most cases, the most abundant animals. However, regional differences in the relative abundance of copepods, ©uphsusids, amphi- pods and ehaetognaths resulted in notable differences in th® plankton population from station to station. In some instances, one or another species dominated. Thus, at Station IS, the oepcpod Calarms tonsus formed the bulk of the catch from 150-0 meters. Surface hauls at Stations 12, 13, 17, 35, 37, 38, yielded very large numbers of .If^ doca^anug minutua,. sp* was predominant at th® surface at four stations (4, 6, 10, and 14) as were eggs at Station 10 in a haul froa 10-0 meters. 2) Abundance of phyt©plankton in th© summer cruise, June & - 16, 1955* It 1® impossible to stat© on th© basis of a survey lasting only two weeks whether the conditions encountered in June 1955, are typical for this period of the year. The 1st® spring and relatively cold June of 1955 may have affected the abundance of diatoms and delayed the period -38- of peak abundance? according to von Hoff»s Law a 10% rise in temperature increases the rate of metabolism 2 to 3 times* Campbell (1929) found that temperature changes and plankton occurrence are definitely correlated within the limits of 10*0 - 15 *0* Within these limits, at least, an increase in temperature is accompanied by an in crease in plankton in th© Strait of Georgia. Although absolute abundance of diatoms during the period of this study i s only a measure of the standing crop i t is probably indicative of a fairly productive area (Fig. 10). The maximum number of diatom cells per liter (124,480) in the Strait of Georgia does not compare with 20,000,000 cells recorded in th® 01yd© Sea in April 1927 (Marshall and Orr, 1927)• Comparison between th® maximum count obtained in June 1955 (25A00»000 vol.) and th® maximum volume reported by Hutchinson and Lucas in July 30, 1927 (H0/l00,000 vol.) show that the values obtained on the latter date were roughly four times higher. This suggests that catches taken in June 1955 were preceding or following a period of greater abundance and that greater quantities could b® expected from the area. Few diatoms were taken at Stations 13, 16, and 17 clos® to the Fraser River estuary (Fig. 10). This region is characterized by a low saMaity (Fig. H) and a high turbidity. Th® latt®r greatly reduces th® depth ©f the photic zone which in turn affects the growth of phyto- plankton. In th® center of the Strait th® standing crop ia June, 1955 was higher in the western portion than in the eastern portions only Station lit, located at the mouth of Vancouver Harbour, wh©r© mor© F i g . 10. Phytoplankton abundance from surface to depths of } 0 , 20, and 50 meters, June 8 - 16, 1955. - 40 - F i g . 11. S a l i n i t y at two yards depth i n the S t r a i t of Georgia from synoptic survey, June 1950 (after Waldichuk, 1952). - 41 - extensive mixing is taking plaoe, showed a relatively high standing crop. Several authors (Hutchinson and Lucas 1931; Tully, 1932) Waldichuk, 1952} have observed a larger flow of Fraser water along the eastern portion of the Strait bringing lower salinities to the area. Temperatures are also colder in this region (Fig. 3). Th© salinity gradient is therefore one of the chief factors affecting the general abundance of phytoplankton in this central region of the Strait. The standing crop of the surface waters at Stations 35, 36, and 38 in the northern area was high (Table II). Tully (1932) found a decrease of phosphate concentration during the summer and low silicate values (1 mg/l. in July) in this area. This decrease in the chemical constituents ean be attributed to phytoplankton activity and sine® the latter region i s located in the less turbulent part of the Strait (Tully, 1954) i t i s evident that depletion of silicates will limit phytoplankton growth. Tully (1932) suggests that other nutrients do aot reach concentrations low enough to limit the development of phyto plankton. fhe highest standing crop appeared south of Point Roberts at Station ©. Hutchinson and Lucas (1932) and Waldichuk (1952) found that strong physical and chemical gradients existed in this region where fresh and salt water mixing occurs. Both fresh water and sea water masses contributed certain favourable factors for th® rapid growth of the phytoplankton population. 42 - 3) Abundance of aooplankton and phytoplanktoa in the f a l l cruise. November 7 - 10, 1955• Tb® collection® taken in November present a picture of th® abundance of plankton in th® central and northern regions ©f the Strait. Sine® the data (Table III) wer® taken only during th© day light period they d© not give a true quantitative value, but only an approximation of th® abundance of plankton i n November. te®pt for a region of moderate concentration (Pig. 12) at th® boundary of th® eentral and southern regions of th® Strait (Stations 7A, SA, 9A, 10A, and UA) and this © wid®ly separated localiti©® of moderate concentrations (Stations ISA, 19A, 20A, 30A, and $$k) th® whole area of the Strait, covered in November, supported a uniformly low concen tration ©f zooplankton. It has already be pointed out that th® water reaches an almost heaogeneous state in the autumn with ©older tempe ratures than in «fune and a small salinity gradient. These two factor© are assumed to b® Malting in November. Th® region of moderate concentration corresponds to the 20a® of greater fresh water and sea water admixture off Point Bobert® wh®r® a high salinity gradient exists in November* Tha center of atoundanc® for th® ©opepod® was i n ta® 50-3 meter zon®. Among th© ©opapeds, the juveniles of Oalanus ftoiarcMcas and Ps®ud#calanus •tawfeaq wer® predominant in 20-0 meter® at Stations 7A, SA., 9A, 10A, HA, 15A, ISA, 19A, 20A, 2oA, 2SA, 3©A» SU» 33A, 35A, and 36** while the adult® of ga^ antt®,, £&mgMm*J&mm% lUMl* llStiS" loaadrcaia wer® predcrateant in 50-0 meters in th® area. The copepod T A B U S H I Estimated srasfcers of zooplankton and volumes of phytoplankton collected Moveaber 7 - ID, 1955 Ho. Position Latitude Longitude Date Time psr Depth W W&ter^rained Zooplankton organisms Phytoplankt< cells per l i t e r 7A 48* 57' 15* I 123* 08« 00* ¥ Jtev.9 1610 10 2.03 4102 *1 7A II « 1620 100 20.29 1028 * 1 SA 48* 55• 51" 1 123* 11» 30" W 1651 50 10.15 1148 <•! SA w « 1705 n o 22.33 660 *1 9a 48* 54' xm i 123* 16 • 12* W 8 1324 20 4.06 603 1 9A » n 1830 100 20.29 408 *1 10A 48° 56t 06" I 123* 18» 16" W a 1752 10 2.00 1460 <1 10A w 1804 150 30.45 408 <1 11A 49* 00« 00" i 123* 18» 30" w a 1510 10 2.03 1761 ^1 HA n 1518 100 20.29 641 3 Ihk 49* 03« 43" 1 123* 26« 21" W H 1400 20 4.06 313 <1 Ikk n 1415 200 40.58 203 1 15A 49* 021 00» 1 123* 31* 45" W n 1304 10 2.03 1136 ^1 154 t? 1315 150 30.45 437 <l ISA 49* 18* 00" g 123° 25' 02" ¥ SOT .7 1335 10 2.03 1599 <1 ISA » 1348 150 30.45 621 <l 19* 49* 15» 22* I 123® 29' 00" W H 1425 50 10.15 1037 1 19A « W 1438 200 40.58 334 ^1 20A 49* 12 • 20* I 123* 33' 15" W n 1522 20 4.06 972 l 20A B 1535 25© 50.75 258 <1 22A 49s 091 38* 1 123* 32' 16" ¥ lev.9 1145 10 2.03 371 <1 22A « ff 1155 100 20.29 309 <1 23A 49* 11* 12» 1 123* 42' 3©M W •tor .7 1645 10 2.03 278 <l 23A tt * 1700 100 20.29 509 1 m 49* 12« 22" 1 123* 39' 15" W 1617 20 4.06 301 3 m 18 1625 50 10.15 241 <1 TABLE I H (©csseladed) Sta* K o . Pesitisa Latitude Leagita id© Bat© Tim® PST Depth Cm) Waterjjtraiaed ©rgaaisjss cel l s per l i t e r 25* 49* 16' 31* I 123* 40* 40" ¥ I©T.9 1005 10 2*03 441 1 254 n 8 2015 50 10*15 407 <• I 264 49* 21* 22« 1 123* 41' 30" M a 0859 20 4*06 451 2 26A » 0913 150 30.45 290 <1 27A 49* 24« 15« » 123* 48* 45* W n 0803 20 4.06 289 1 m a tt « 0814 60 12.18 301 1 284 49* 23» 22« 1 123* 54' 24" W Iter .8 1030 20 4.06 1354 6 284 it * 1045 230 46.69 234 1 49* 22* 12* » 124* Gl* 30* W 1145 65 13*20 235 1 it » 1165 150 30.45 165 < 1 304 49* 26' 45" H 123* 54» 15" ¥ n 0940 20 2.03 811 2 3GA 8 «t 0955 150 30.45 243 1 31A 49* 19* 45" » 323* 51* 30" tf it 0845 10 2.03 520 2 3M # n 0900 200 20.29 269 <1 324 49* 15» 16" I 123*49' 3QH w «* 0755 20 4 «06 173 3 324 *s 0814 100 20.29 234 <1 334 49* 23« 38" » 124* 16' 05" W » 1310 10 2.03 765 <1 33* » 1335 200 40.58 242 <1 344 49* 26* 10» » 124* 221 50" ¥ 1423 50 10.15 250 4 344 1442 150 30.45 203 3 35a 49* 29' 22«* I 124* 30* 20" ¥ a 2518 20 4.06 428 2 35* » 1530 100 20.29 410 <1 344 49* 33* 28* i 124* 26* 50" W tt 1612 10 2.03 2390 10 344 ti 1630 100 20.29 304 1 374 49* 36' 0O« S 124* 33* 45® V *t 1713 50 10 05 500 2 374 n 1737 100 20.29 803 2 F i g . 12. Zooplankton abundance from surface to depths of 10, 20, and 50 meters, Nov. 7 - 10, 1955. -46 association, with Calanus finmarohicus and Pseudocalaaus mjautus as predominant representative®, most play an important role in the surface economy of the Strait in November. Ho juvenile ©mphausids were ©aught in November aad adults were found almost exclusively in the deeper hauls, fhe adults dominated the catch at Station Chaetognaths and amphipods were found in small numbers at almost every station i a the deeper hauls aad on a few occasions in 50-0 meters. Diatoms were so sparse in November as to b® almost insignificant. Stations 2S&, 34A, 36A, and 37& supported low concentrations of Chaetoceros c oncavicornis. ^^p^^i^iodls^^ys w^tilegii^ was csoimon at awst of the stations visited in Novemter. Its, j^^y^w^si^r, i ^ . r M ^ s . I/M^s^iss 1) Vertical DlstribmticB. In ©charing the abundance of the different .groups of plaaktcn in the upper 50 meters frm one area of the- Strait to the other, the problem of vertical distribution arises, fhe relative- abundance of th® different groups may vary depending, on whether the sample earns from 10-©; meters, 30-0 meters, 50-0 meters or deeper. It Station 2f, for example, whore .hauls were made at 10-0, .20-0 and 50-0 meters, eggs weze fredcraimaat from 10-0 meter®., copepods froa 20-0 meters., and Juv enile eaphausids. from 50-0- meters. In order to study th® vertical distribution, copepods were selected because they were the most 47 important representatives ©# th® plankton and contributed many species to th® community* Analysis of sample® containing copepods shows that those animals f a l l into three distinct group®s 1* th® surface forms* 2. th® subsurface forms, 3* th® deep forms* When a specie® i s common in the deep as well as in the shallow hauls, i t can be said that this species inhabit® th© surface layer. On th® other hand, i f a speeies is never caught in the shallow haul and Is abundant in th® deep hauls, i t is recognised as a deep form. When we compare the abundance of one species at different depths, its vertical distribution can b© determined within narrow limits (Fig. 1 3 ) . Speeies such as Acartla claufi, A c a r ^ Ifflg^remis, SgHtrggajgs Vwm^mn. mm* d^aafetfl®. .Bj^abldoeera amphitrites inhabit the surfaco layers (10-0, 20-0, aad 50-0 meters), fei^fflf mti&m JSESSIH' s&SbatffafaWA 2*£Z£> and 'iMJidius tanuisDinxis live in th® deeper layers (250-0 meters). Other groups of animals in the plankton also seem to follow a similar patten? ot distribution. Euphauaids as a group ar© represented by several larval stages, fhe aauplii and metanauplii wer® generally abundant at 10-G meters, while th® ealyptopis, furcilia and eyrtopia stage® were found deeper. Juvenile Calanus were abundant at Stations 12 and 35 in the upper 20 motor®. Qik®pl®ura waa predominant at 10-0 meters, and was seldom found deeper. 2) Horizontal distribution at constant depth. Variations in abundance at constant depth for June S - 16, ar© - 4a - Depth in Ranges ©f Meters speeies X Q m Q ^ 2 5 ( M ) UiX>nona sp • Pssudccalanus minutus Acartia clausi A. longiremis Centropags® mcmurrichi Tortams disoaudatus Microsetella rosea SurfaM Oneaea conif era hirundoides Paraealaaus parvus Coryoaeus affinia Calanus finaar@hi@us Maptesais sp* Calanus tonsus Epilabldooera amphitrltes DiosacouE spinasus Metridia longa Gaidius pungens Ascomyzon rubrum ^ Eurytemora johanseni forms Metridia luoens guebaeta japonica Mlerooalanus pusHlus Idya fureata Ceatregaptilus poreellus Ghirldius tenuispinu® Scoleeitbrieella form® minor A@tid®us armatus Gandacia Columbia© iarpa@ti©u® unir®mis Fig* 13* Histogram showing th® occurrence of copepods at different depths, June 8 - 16, If55* Th® heavy lin®s indicate th® zones of maximum abundance* 49 demonstrated by the histograms (Pig* 14). Th® total sooplankton values are plotted in numbers per cubic meter. The shaded portion of the histograms represents the number of copepods in the catch and the narrow column to the right shows the volume of diatom cells per liter present in the same plankton sample. At 10-0 meters, a l l stations but two (Stations 7 and 30) have concentrations higher than 2000 animals per cubic meterj seven dis play concentrations ranging from 2000 to 4000 animals (Stations 1, 2, 16, 1®, 33* 36, and 41)I tbree more exhibit numbers of the order of 4O00 to 6000 animals (Stations 23, 25, and 3D, and seven have higher concentrations (Stations 4* 10, 11, 12, 13, 15, and 22). Aa inverse correlation exists at 13 out of 19 stations, between zooplankton quantities and diatom volumes. Where high blooms of diatoms occur, such as at Stations 10, IS, 33, 36, and 41, the number of animals is low. Station 12 has a very large number of animals and a low diatom population, low diatom concentration are also found at Stations 1, 2, 7, 11, 12, 13, 16, 23* 25, and 30. The situation i s somewhat different at 20-0 meters. Station® 5* 26, 27, and 28 have concentrations lolow 2000 animals per cubic meterj Station 14 shows a value of 2800 animals per cubic meterj Stations 17, 20, 24, 25, 32, and 38* have values ranging from 4000 t® 6000 animals* and Stations 21 and 35 have over 10,000 animals per cubic meter. An inverse correlation between sooplankton and phytoplanktoi i s apparent at Station 38 where diatoms predemiaate and mooplankton counts are low. The number of animals increases markedly at Station 35, n@ar by, where - 50 - 1 4 T 10 i * i i i» a i i a ma » » « STATION N««l[« D | 9 T M 10 • IT to II H B » !l STA T t OH aUMIC* DC ' I n 2 0 - i t is * i i » r I I » » « STATION NUMSC* DIPT* SOm 'jLiillltl J t 4 ll « 2 2 ! ) ! i V S t » M 5 7 Fig. 14. '"Histograms shovdng the variations of zooplankton an! phytoplankton at constant depths, June 8 - 16, 1955--51- diatoms are loss numerous. At Stations 5* 17, 20, 24, 25, 26, 27, and 26, diatom volumes are law. Much higher counts are recorded at Stations 21 and 35 • At this depth copepods s t i l l form the major part of the catch, as shown at Stations 17, 25, 3 2 , 35, and 38* At §0*0 meters only Station 13 had a concentration exceeding 4000 animals per cubic meterj seven exceeded 2000 (Stations 1, 6, 12, 24, 25, 34, and 37) and five had less than 2000 animals per cubic meter (Stations S, 19, 27, 29, and 43)• Station 6, which exhibits th® highest diatom concentration is located off Point Roberts, a region of relatively great turbulence. Moderate diatom concentrations also occur at Stations 12 and 29. Oikopleura sp. dominated th® catch at Station 6, sggs and ouph- ausids wer® found to predominate over copepods at Station 13. At a l l other stations copepods wer® always th® dominant group of animals at 50-0 meters. Greater depths d© not need to be considered in detail* It i s evident that quantities decrease very rapidly below 50 meters. A l l stations but five have concentrations below 2000 animals per cubic meter. Th® other five stations (4, 21, 34, 35, and 37) have values ranging from 2000 to 4000 animals per cubic meter. Applying th® sam® analysis for the lighter November catehes, a similar type of distribution i s found (Fig. 15). At 10-0 meters a higher concentration of animals per cubic meter is found than at any other depths, and eepspods pradomiaat®* At ZhO and 50-0 meters copepods ar© s t i l l the predominant form, but th® relative concentrations of animals ar® much smaller. B®low 50 meters, - 52 - 111 I g I M l*A 2QA 2 « A 2*A JTA 2 I A S T A T I O N N U M B E R D E P T H 2 0 B 111 lilt TA K M HA OA ISA ZW 23* 25* » * SA « A 5AA S T A T I O N N'JM • [ » OtPTM I 0 » ? 1 1 S A 2 « A 2SA 27A 2 % M » STA S T A T I O N N U M B E R D E P T H M « IIIJIJULLJ i i I B H • a M I • g Ji. IIA 22A 2JA S A S2A SB* M A STA O A ISA l » A 2*A 2 S A JOA S4A HA ISA 5SA 28* 20A S T A T I O N N U M B E R -too* — • O O " — — — ZOOm 2 5 0 » 2 S 0 « i F i g . 15. Histograms showing the v a r i a t i o n s of zooplankton at constant depths, November 7 - 10, 1955* - 53 - where mature Individuals aggregate, catches are very small, except for chaetognath®, euphausids, and amphdpods. Diatom volumes are so small in Hovember that they do not appear on the histograms* 4* ilpbsraet^rls1tioBiiio^ the Most Important Sreufs. 1) Copepods* Copepods, either in the adult or larval stages, generally formed the main bulk of the aooplankton. there were more species and more Individuals present in June than in Hovember* Fraser (1918) also noted fewer numbers of copepods in the winter at Departure Bay* In the month of June, whenever copepods dominated the catch, tM!$r**L*m 9 s M t « > 3#»flW4»> and Mhena sp* were mainly responsible* These three species together contributed 6556 of a l l cope pods taken during the cruise. They were supplemented by Galanua sp. (15*). Metridia lon^a {%}> l^uoalanus bunfol (%)> Ifetridia lueens (3#)» and Qentropages momurrichi (3$). A l l ©ther species contributed together only 2j$ of the total catch of copepods, in terms of numbers. Wherever juveniles were very abundant the same three doatnaafc a pedes were responsible* Calaaus sp. also contributed very high percentages of juveniles. Ia ths month of Hovember, fe^eea^us, fltifflfffoft* Wftm SP" s n d Calanus finmarchlcus were the most numerous representatives of the goeplaiikton and formed 7$ of the total number of copepods. Next earns Metridia lueens (10$),,,g^Ieclthricella minor (2$), Merocalams pusillus (2$), Corycaeus affinis (2$), Acartia longiremis (2$), Para- ealams parvus (1$), and Buchaeta Japonioa (2$)j a l l other species 14 formed lees than % of the total catch. The following summarises the featured of the species regarded as significant. little attention is given here to the rarer species which must have some importance but contributed little to this study. A systematic treatment of the various species common in th® British Columbia waters has been prepared by Campbell (1929) and most of the species studied hex* have been reported as characteristic of the area. J^ seud^ ca^ nug minutus,. The commonest species in June and November has a universal distribution in the Strait of Georgia. Jt is very abundant through out the area and is found at all depths sampled. This suggests wide limits of survival for the species. It is one of the eewoaest species at Friday Harbor (Johnson, 1932), where i t is most abundant in the spring and autumn. Cameron (1955) mentions that P. minutus w so common everywhere in the Queen Charlotte Islands as to be useless as an indicator of water movements. The percentages of P. minutus forming the total catch ar® fairly uniform for June aad Novembers 29$ of the total number in June, and 28$ in November. There is a definite degree of variation in th® rati© of males, females and Juveniles forming the catch for different periods of the year* The males appear to be more abundant at the onset of breeding. For example, in June, from a catch of 7629 individuals, 12$ were males and 3$ females* Several females were egg-bearing and already 5<$ of the catch was made up of juveniles. Th® number ©f males diainishes more - 55 ~ rapidly than th® female® after the breeding season. Thus i n November, 1955* 139© individuals were caught and th® males amounted to only i$ of th® catch, and th® females to 25%. By this time breeding mast have been completed by this speeies, because no ®gg-bearing females could be found, furthexmer®, th® .Juveniles accounted for 1% of th© catch. Aoartia The genus Acartia i® represented by two species in th® Strait of Georgia: A. \m$&xwA® and 4. clans*. Of th© two sp®ci®»» Aeartla lon^ireinis i s by far the most abundant aad is characteristic of th® whole Strait. It seems to be present at a l l seasons but shows wide Iluetuatienf in abundance. Thus 1# of th® cepepeds taken in *?ua© was made up ©f A.. loajdresds, while th® same species accounted for less than % of the catch i a Sorember. Wilson (1938) a@nti«s that in 6©EpHBy with A. clausi th®s® species f©» the chief constituents ©f the plankton @f Chesapeake lay. Blgelow and I^sli® (1930) found k* l^mimmiM imimek in Monterey iay at station® n®ar land and in comparatively shallow part® et a few station© farther ©ut. At Friday Barber, Johnson (1932) »@t®s that 4. IM&M&M i s present at all . seasons but never in very large number®. He gives th® monthly distributim of XmtAxmOM in th® year® 19?7<-19t0, 1928-1929 (Table I f ) . - 56 - TABLE If Average monthly distribution of Acartia ImtdrmsL® to 1927-192® and 1928-1929 (after Johnson, 1932) A* IS JM^ r.eM.S Sept* Oct. Mm. Bee* Jan. Feb* March Apr. May June July Aug 1927 - 1928 * 8 17 4 1 3 4 5 9 9 10 2 1928 - 1929 * + 2 1 + + + • 3 5 5 2 + pr< jsent (counts ai limal; 3 in 1 ml of sample) Th© abundance of Aeartia in June ( f i g . 16) corresponded to the peak of main increase i n the Fraser discharge, and since th© genus i s known to be euryhaline i t i s suggested that i n our region i t reaches it s peak abundance in summer, when low salinity warm water i s widely distributed. It i s distributed i n the upper 20 meters throughout th© Strait and reaches i t s maximum concent rations at Stations 13 and 21, which are located near the middle of the Strait opposite the Fraser River estuary. The waters become almost isottiermal i n Hovember at and th© upper aone of low salinity i s found only i n the vicinity of the Fraser i a the upper four meters (Tully and Sedimead, 1954). These physical conditions may account for the low quantities of both species of Acartia found i n Soveaber and for their aistribmtion in the deeper waters. During the breeding season, males and females share th© catch i n fairly uniform numbers, 25$ for the males, and 32$ for the females. When breeding is not taking place, females far outnumber the males. For example, i n Kovember when the temperatures wer® too cold for the species - 57 - 15 a. U J t3 i- I 2 J temp. L i 2 00 o o O. UJ 100 a. O o u i OJ 2 I 2 4 7 10 II 12 13 15 16 18 22 23 25 3 0 31 33 36 41 S T A T I O N N U M B E R F i g . 16 (a) Numbers o f A c a r t i a longiremis found i n the upper 10 meters p l o t t e d against surface temp eratures, June S - 16, 1955* -40C o Ui r-300 ' 2 0 0 o m > ~-in Q O 0. UI a. o o u i CD ( 0 0 5 14 17 2 0 2 4 2 5 2 6 27 2 8 32 35 3 8 S T A T I O N tf 'J M 8 E. H F i g . 16 (b) Numbers of A c a r t i a longiremis found i n the upper 20 meters plotted against surface temp eratures, June 8 - 16, 1955* - 58- to reproduce (aiesbreeht, 1905 ex Cameron, 1955 gives U°C as the minimum temperature for reproduction) but warm enough for survival, the female® accounted for SQg of the catch, and th® males for 1 $ . Thezfow fh© few copepodlds stage® taken in the f a l l wer© in a late period of development, and showed many adult characteristics. Aeartla clausi Is euryhalJjie (Cameron, 1955) and should have been found in large numbers in June, but only scattered animals were found throughout the "upper zone". Ho reason, a® yet, can account for this unusual distribution since Cameron (1955) reported th® species a® CCSSBOB in most areas in the Queen Charlotte Island®. The possibility arise® that th® main concentration has been missed, or existed outside the areas investigated* £. elausi i s rare in Nevest»©rj two specimen® only have been found at Station 7A. Qithon^r This Mcrocopapod ha® two representatives in the Strait ©f Oeergi&t t» MM&MPm MMSSm* *» analysis of several samples showed that £. mMMMm ^ »re eewon than £. S&S&m* Th» former was very abundant in the Strait in June when i t formed Ufa. ef th® catch, but was s t i l l mere important in November, when i t formed 7.% of the catch. Sapaples Urn most stations were analysed only for total counts ef th© genus. At several stations, however, th© individuals were determined to specie® and subdivided into sexes. The ©ample taken at Station 11 which i s a representative sample from 100-0 meters indicated th© following composition* 0. helgolandjea, 3 males, 66 females, and 4 Juvenile®} 0. pluaifera, ? females. Every sample thus analysed produced a much greater ma*** of 0. .M£$M$$M' - 59 - Olthona was found at a l l depths at a l l stations i n abundance but with a greater eonoeatratlen i n 50-20 meters. 0. helgolandiea which i s a l i t t o r a l species (Wilson, 1932), i s able to stand a wide rang© of physical, and chemical fluctuations of the waters. Its abundance suggests limits of survival beyond those found i n the Strait. On the other hand, p.. BJumifera> which i s a pelagic specie® and chiefly tropical i n i t s distribution (Wilson, 1932), 1® not able to achieve great abundance unless th® waters have th® optimum condition® for th® reproduction and development of th© species, loth a high temperature and salinity w i l l be required. Sine® these conditions are ®©Mea met i n the Strait ©f Georgia i a sunsaer, this aay account for the scarcity of the specie®. When the temperature and salinity distributions ar© more homogeneous -in loveaber (see II) Oitheja MMmMm s t a i n s a higher eeneentratlea. h^l^olantlica i s also reported to be mm numerous i n the f a l l m the Pacific Coast at Friday Harbor (Johnson, lf|2) and at La Jolla (Esterly, 1928)* fhe pattern of distribution ©f this genu® Is d i f f i c u l t to inter pret from the available data. Because ©f tsputotaLe d i f f i c u l t i e s , the juvenile® ef latest, m a n s^mn MmmMme^ m% identified with certainty to specie©• two things atuft® this genus iapertaats f i r s t , th® presence of a larg© number of Juveniles, and second, th® presence ©f a great swara of adults at Statiesa 18 (Fig. 5)» Juveniles of QaXwaw aecomnted for Ut% of th® eatch i a June aad 2|$ i n lovember, thus making i t mm of the meet significant owistituents mi the 8©oplaofeten. This swarming - 6 0 - behaviour has been noted by several authors (Eaterly, 1905J Bigelow and Leslie, 193©,* •Johnson, 1932). It seems unusual that palanus ||nmarohloua. and Mm&lmm should breed in such numbers in the Strait since both are more pelagic than littoral i n distribution (Sars, 1903) and thus mast result from invasions from oceanic water through the Strait of Juan de Fusa. Whan more i s known about the distribution of each species in the Straits of Georgia and Juan de Fusa, some more apparent explanation may be evident. The adults of C. fi^marehicus were present at a l l but three stations and always in small numbers. A total of 13 males and ?0 f©mate s were identified. C. tQnaus ©eourred in much larger numbers than C. f i n - raarchicus. A total of 909 individuals were identified as males. As for £. erlstatus, only four Immature females were found in the Strait. la Hovember, only G. finmarchicuS; could be found, and i t was never present in abundance. The juveniles were spread throughout the area, but were most abundant at Stations fk and $k» within the influence of the Fraser l i v e r . Metridia Metridia i s oa© of the most prominent genera among ths loss numerous copepods found in the Strait of Georgia* It i s represented by two apeelest M. jffltw* I* I&BS&i The species J§* J ^ e » l Is generally found with Manjg, |^arghjcu£ in 100-0 meters hauls. The males, which are lea® numerous than the females (193 males, 512 females) are found in shallower water than th® females. In M0vember the males were found at a l l depths. Samples taken - 61 - at 20-0 meters and 10-0 meters yielded several adult specimens* The females, on the ©ther hand, were absent; from the upper 50 meters* Metridia has an extensive vertical migration. Esterly (1920) notes that they ar® absent from the surface during the day, but are very abundant at the surfaee at night. The males of J£. lueens, although less abundant than the females, are more generally distributed* Males were found at 31 stations in June, and females at 26 . Zn Movember males were taken at 24 stations, and females were found at 18. M. Jgoens is more numerous in the f a l l . Like aalanus fainmarehleus, i t has two breeding periods, on© i n the spring* and on© in the f a l l . The spring spawn must take place quite early in the season in the Strait, since in ®4d~June .only 16$ of the species were made up of young, whil® were adults. Bxeept for two males of jetridja longa, a l l the Movember eaten of Metridia was mad® up of Jf* lueens. Breeding of this species was taking place extensively in Movember. The catch i n November was as followsi 20 males, 33$ females, and 43$ young. There ar© wide seasonal fluctuations in th® abundance of Metridia lonjffi. It was found in greater numbers than ]4. lucsns. in June, but was very rare l a Movember. It i s not known whether this i s a typical seasonal variation, gucalanus buneii Campbell (1929) mentions the presence of E. el^&gatus near Station 1 in the Strait of Georgia* As the main distinctive character of this species she claims the presence of 'a thorax with rounded ends to be diagnostic * I believe the specimens which she records belong to the 62 - species »wiXwai» bungli. Johnson (1932) and Davis (194°) associate the above character with g. brogii and not with J|. elongatus* the latter bears points laterally on the posterior thoracic border. Bucalaaus bunidi was found during th© June ©ruise only, fhe catches were made up mostly of juveniles that live in the upper layers. Cameron (1955) did not find jg. bunM^ shallower thaa 50 »et@rs in the Queen Charlotte Islands, but i t was found in greater numbers in 50-0 meters during this study. The adult males and females were generally found in the deep tows, but a good percentage were also distributed from 100*50 meters. Because of the uniformity of temperature and salinity of the lower son® from 50 meter® down, i t i s not surprising to find them in shallewer depths in the Strait than in the Queen Charlotte Islands* The greatest abundance of this species in Pacific waters i s recorded at 200 fathoms at Scripps (Beterly, 1928). The greatest number® of E. bunsii wero caught at Stations 13 and 21, but the distribution was ubi<tuitoug in the strait of Georgia. This ealanoid was also common in June only in the Strait ©f Georgia. Unlike the preceding species, i t is a true pelagic form, occurring close to the surfaee «ff the sea* Two distinct areas #f abidance were £m*A* the t i n t located around Stations 13, 20, 21, and 22, and the other centered around Stations 34* 35, 37. and JfcS ^ t r o ^ e f a^irrJohi can apparently tolerate wide ranges of XtoetuaMon in salinity, as shown by i t s presents in water® of salinity as low as t £ , and as high as 20% , and also by the fact that heavy breeding was taking place in parts of the - 63 - Strait having a salinity lee® than 1 0 $ , • Twenty-four percent were males,- 1# were females, and 57$ were iaaatwe. In these tw© regions, relatively high phvtoplankton concentrations occur. Where there was a very low ©eneentration ©f dlateas such as at Stations 1 , 2 , 4, 5 , 7, 11 , 15, 16, 17, 19, 27, 41, and 43 this speeies of eepeped was less abundant. In regions of very high phytoplaakton ©oncentratien®, such as at Stations' 6 , 10, 12, and 36 th© concentrations of g. meaurrichi were also low. It seems then that the species needs a supply of diatoms high enough to provide ample food, but not so high that i t ©ay cause exclusion. "According to Hardy's view (1936) .... certain of the animals during a part of the day swim upward into the layer of water where diatoms ar® being produced* fhe duration of their sojourn i n the upper layer i s inversely related to the concentration of th® phytoplsak- ton. Thus they ar® excluded vertically for a considerable period of time when, diatitt production has resulted i n a dense swarm of diatoms'1 (Hardy, 1936 jg Sverdrup et a l , 1954)* fh® young ©f th® specie® were most abundant i n 20*0 meters, and th® -adult a l i t t l e deeper (fable ?)* WOM f iuafeer® of juvenile and adult Jga&SgKW B i P I S l g S I a t 10-0 , 20-0, 50*0, 100-©, aad 150-0 meters, June 9 - 16, 1955* 150-0 Juvenile® 68 107 H I 143 69 Adult® 41 70 ' f j f j SO 64- Other species ef restricted distribution. Among the species encountered occasionally but never i n abundance, in the plankton samples were* Qncaea gon^fera, Scolecithrioella minor, m&^j^E^m> smauem mJmPM Mm&^> .mm* Mm warn* tm*mw m$mM>m» M£m$g*m m^M^m* M & H Wm*m> I I M t e and a few others. The- speoiea not l i s t e d were represented by only a few scattered individual®. 9mm mMm **• b e e n s h o w n i n the polar regions as well as i n the tropics (Wilson, 1932). It can therefore adapt i t s e l f to considerable fluctuations i n th® environment. In the Queen Charlotte Island®, Cameron ( 1 9 5 5 ) found that i t s presence was generally character i s t i c i n areas of high surface temperature (above 1 3 * 5 ^ 2 ) and that i t inhabited the upper 75 meters. It i s distributed even deeper i n the Strait, of Georgia. It was found at a l l depths, but never i n abundance i n hauls taken shallower than 100 meters. It was common at Stations 5 , 1 4 , 2 f , and H at 100 meters or deeper. Ten males and 90 females were counted from 33 .stations i n June. A l l the males but ©no were found attached to the females, indicating that th© species breed© i n these latitudes. In November 2 5 female® were noted at 16 differaat stations, but n^aales were found* $miWW*<Um Mm *»* wasienally i n June, but frequently i n November. Typically this copepod i s a pelagic form (Sara, 1903) and i s not found i n low salinity water. Its distribution i n th® $trait varied with the seasons• In June neither adults nor young wess found i n th® supplementary hauls taken shallower than 50 meters, but both wore present i n the deeper haul®-. The high salinity of the "lower zone" - 6 5 - waa apparently suitable for the specie®, judging by the abundance of copepodlds present • In Movember both adults and young occurred through out the water column, even i n th® 10-0 meters hauls, fhey were present throughout the area, but never i n large numbers. In November juveniles accounted for k% ef the catch, adult males 13%, and adult females 40$. BMmQsmm-m^M.is °» e o£ t h e «all«*t calanoid®. It i s widely distributed i n deep water but never found i n the upper 50 meters. In June i t was present at two-thirds of the stations. The centers of abundance were located at Stations 20 and 33 . Hales termed h% of the catch, and females 53$ • !• p u s i ^ s was caught most eeawsly i n th© November hauls. It was absent at one station and common at Station® 14A, 20A, and 28A. The catch ©©^ri®ed 43^ males, 56$ female®, and 3$ young. According to Esterly (192S) Oorycaeu® affiai® occur® i n greatest abundance i n Jw-Septewber., and least i n F©bruary**y at La J o l l a . Baring the two year© that observations were made, a period of least abundance began i n November and extended through June* On the ether hand Esterly (192®) feund there was a great increase i n July. The data recorded here does not agree with hi® findings. Qoryeaeug affial® appear® to be much more numerous and widespread i n November than i n .June in the Strait of Georgia. In June i t was taken i n leas than one- half of the tows, and never occurred i n any quantity. In November i t was abundant at several stations and present i n more than two-thirds of the samples* A l l representative® obtained were adult and same froa the %pper zone".. pckaeta ,1a>^ eniea was the largest of the ©epepod® found i n the - 66 - Strait of Georgia. Im. June, males, females, and young ware always found deeper than 50 meters and were never In large numbers. They were present at half the stations. The males made 30$ of th® catch, the females 10$, and the young 60$. 35. .japonica was present at a l l stations in Kovember and at four of them In fair awmbers. The young were found in shallow water and ths adults in deeper water. Hales formed 16$ of the total number, females 15$, and juveniles 69$. Faracalsnus parvus., fery small numbers were counted in June. The species was found at almost every station in lovember although never In abundance. It usually ©eourred near the surfaee ef th© water. The females always outnumbered the males (93$ against 7$). MM* ^eeaudatus. Is defined as a swsmer species by Wilson (1932). It was never found in any quantity during this study. It appear® to be a ©uryhaline species* In the summer it was confined to the "upper sone1* and in the autumn i t was restricted to the area adjacent to th® fraser estuary* Only males (65$) aad young (35^ ) were found in November. MMM®$m JSHMISl W tof recently in th® summer, and always in small numbers. The catch was made up mostly of young (61$)* Th® distribution could only b© estimated, due to low catches. On the basis of the distribution of those animals taken, the species Is assumed to congregate in the upper ao meters* In the .month of Uovember only one juvenile was seen in a l l the samples studied. M t e mom m d m^i^m smfadm b r i b e d as - 6 7 - Areti© speeies by Sars (1903)• They were very rare In Jane and occurred in the "lower aone". They were found In two-thirds of the hauls in November, but again in email numbers. All ether forms listed (see pp. 19, 20, 21) but not discussed were represented by only a few individuale and were too rare to enable drawing any ©meluslen® from their distribution. 2) Appendioulsrians. The only appendicularia identified to genus was Qikogleura. Th® widespread occurrence of these appendioularians (Fig. 17) is indicated in th® June plankton* demonstrating the favourable conditions provided in th® Strait of Georgia for the growth of these organism®. Thus Oileenlsura was sufficiently abundant to be given th© second place in the list of abundant eooplankters. In the shallow.tews, appendioularians were represented only by larvae which were found at all station®, some times in numbers great enough to suggest centers of prediction. In such eases they far exceedulh© number of copeped® as illustrated at Station® 2, 4, 6 , 10, 14, 15, 22, and 41 (Table I). Johnson (1932) never found them in great abundance at Friday Harbor, but found them constantly present. Be also found a slight increase in June and October, when temperature®, were apparently optima® at 9*3*0 - I0*6*@. the larger numbers indicated above were found slightly below 12*13 in th® Strait « f Georgia* Bigelow (1930) feuwl 0. labradorenais for the most part in tes^ eratur®® below 12*6. According t© this author, "sine® it is most plentiful in temperatures of 12% - 13*0 at U Jolla, 12 *C may be set as its upper optimum limit in th® northeastern Pacific" It can thus - 68 - I 2 4 t K) II 12 13 19 16 8 22 23 2 5 30 31 33 3 6 41 STATION NUMBER Fig.1?. Numbers of Oikopleura spp. found in the upper 10 meters plotted against surface temperatures, June 8-16, 1955. V - 69 - b® concluded that when temperatures of this order exist i n th© Strait, such as ware present i n June, 1955, appendieularians will reach a peak of abundance or an 'increase i n numbers. Campbell (1929) found them uniformly distributed at a l l depths i n the Strait of Seorgla. She reported also a greater frequency i n surfaee hauls (5-0 yards) at 7 ^ of th© stations, but she made no mention ©f heavy concentrations i n her summer catches* Th® hauls made i n lovember yielded only small numbers ©f Oiko- pleura. Apparently their period of abundance does aot occur i n the autumn, or at least i n lovember, because only scattered adults were taken during this period. 3) luphausids. SuphausAds pass through a number of larval stages -in their growth from the eggs to the adult individuals. The literature i s somewhat confused concerning the number of stages* ivory author recognises the f i r s t six stages: naupHi I and 2, aetanauplii* and ealyptopig 1, 2, and 3* They are succeeded by various f u r c i i i a and eyrtopia stages. Buud (1932) has adopted a limited number ©f stage®» nauplil 1 and 2, metanauplii, ©alyptopis 1, 2, aad % early f u r c i i i a , Intermediate f u r c i i i a , late fureiHa, and a H eyrtopia.. the samples studied ©ontaiaed a l l the larval stages, but for the purpose of this discussion I have limited treatment to the following number of developmental stages! - 70 - 1. nauplii and raetanauplli, 2. a H calyptepis ®tag©s, 3. a l l f u r e i l i a stages, 4. a l l cyrtopia stag©©. Ho adults were taken at any of the station® that yielded larvae. • fhe method of reproduction of this crustacean 1® very similar to teat which occur® i n the copepods. fhe eggs are shed i n the water, hut the growth i s slow and the animals do not reach sexual maturity u n t i l they ar® two years old (Huud, 1932)• The euphsusids were present at every station i a at least s «e stage of development i n June* Mauplii and metanauplii formed 9$ ©f the catch, calyptopie 4Q£, f u r e i l i a 43$, aad cyrtopia d£. The supple mentary hauls i n 20-0 meter® and 10-0 meter® contained more than half of the nauplii and metanauplii, a® i t was evident that the two larval stages weas concentrated i n th© surface layers. Oalyptopis were also found i n th© 10*43 meters but wer© more abundant i n 50-0 meters and 100*0 meters, suggesting a deeper distribution. Fureilia were abundant at a l l depth®, but cyrtopia wer© only found twice i n abundance above 50 meter®. This indicates that the species has a deeper distribution as the animal® develop (Table VI). S© larval stages of ©uphausid® were found in Moveiaber i n the Strait of Georgia. Some sis® variations ©eourred, but always within the adult stage. The minimum length found was twenty-nine ram. and some ©uphausids were a® long as 45 mm. Total count® i n each sample are given i n fable TH. 71 - T A B 1 E V I LarmL stag©©* by numbers, o f eupaauslds, June a - 16, 1955 Stn. So. Bat© leptn (a) fSaupHi and Oalyptopis FOTcUla Cyrtopia Mstanauplii 1 June 13 10 1 - - 1 » 50 1 I 5 1 2 M 10 1 4 1 - 2 W 80 1 3 5 2 4 » 10 4 1 - 4 « 100 5 12 12 1 5 « 20 - 1 2 -5 0 200 - 3 *» 10 6 H 50 35 » 3 7 ti 10 1 1 - •» 7 M 90 1 * 1 i n 5© - 1 - 17 s n 110 <• 1 13 9 10 M 10 - 1 » 1 10 H 150 4 2 1 11 M 10 33 18 — u « 100 - 44 20 11 12 10 74 7 1 3 12 n 50 3 3 4 1 13 8 10 - 2 «. ** 13 tt 50 - 9 17 12 14 June 14 to 4 1 2 1 H 200 11 2 6 3 15 « 10 1 1 1 ** 15 « 150 - 2 6 3 16 4mm 13 10 3 6 < • 16 » 100 13 8 25 17 20 4 3 3 1 17 « 150 5 8 18 18 12 • 18 •Tun© 14 10 - 5 1 18 8 15© - 1 17 1 19 n 50 7 — 1 19 a 200 8 4 1 — 20 » 20 4 10 5 2 20 250 4 8 11 6 - 72 - WB3t fl (©onoludoa) No. OKU Septa MaupUi MetanaupHi 8»lyptopi© f t i r o l l i a OjttUpi* 2 1 June 13 2 0 U 46 7 5 1 21 « 1 5 © ? 133 160 21 2 2 Juno 1 4 1 0 3 1 6 6 « , 2 2 1 0 0 6 6 4 1 23 Juno 1 6 1 0 - «. m 2 3 1 0 0 2 <m - 24 Jan® 1 4 2 0 t 2 2 2 4 » 5 0 3 9 5 2 5 Juno 1 6 10 1 1 2 — 25 » 2© • 5 3 — 25 ii 5 0 1 1 3 12 - 25 » 1 0 0 3 29 1 2 1 25 w 1 5 0 5 42 4 1 1 2 6 June 1 4 2 0 «* - 1 1 26 ii 1 5 0 *. 3 3 1 2 7 M 20 «, - 1 - 2 7 * 5 0 1 1 M H 2 0 - 2 - 33 26 M 2 3 0 1 2 1 3 29 Juno 1 5 5 0 1 2 * I 29 « 1 5 © «• 1 2 1 3 0 Jua® 1 4 1 0 * 2 1 I ! 1 5 0 n 1 3 1 si Juno 1 5 1 0 - 3 1 5 1 5 1 « im - 2 f 11 1 32 2 0 3 7 «# «* 32 1 0 0 2 6 * • «• 3 3 H 1 0 1 - * ** 3 3 a 2 0 0 4 2 5 34 2 34 « 5 0 11 2 4 1 $ 4 « 1 5 0 - 2 6 65 1 5 5 2 0 * 2 4 3 5 « 1 0 0 1 37 3 9 3 I? tt 10 * 1 16 *» 3 7 1 0 0 5 7 9 1 3 « 5© - 47 37 | | M 1 0 0 3 5 5 0 3 # 2 0 - 7 *• ^ - 3 § » 1 0 0 -* 3 2 4 4 1 Jan® 0 1 0 1 1 2 4 1 tt m 13 1 8 1 1 ** 4 3 Jua® f 5 0 1 1 1 73 - TkffiM ?II Concentration of adult euphauslds taken at different depths, based on a total count of the animals i n each sample, lovember 8 - 11, 1955 Depth to 1 2 m 3 where of adult euphauslds (12 individual samples) 4 5 6 7 3 9 10 11 12 10 0 42 O 0 0 0 0 0 0 0 0 0 20 3i 0 0 0 0 0 0 0 0 50 94 0 8 0 0 0 60 0 65 0 100 m 20 67 24 15 31 6 41 32 122. no 103 150 29 53 11 60 24 21 ? 151 200 24 46 22 230 22 250 152 fhe four Instances i n which adult euphauslds wer© found above 50 meters may be indicative of t i d a l mixing bringing up deeper forms to th© surface layers* Three of these four hauls, for example, were made off Active Pass, and the fourth haul was made off Gabriola Pass. Strong t i d a l currents aad considerable mixing take place at both these points.. fw@aty-feur haul® were made at depths exceeding 100 aster®, and each oa© contained ©uph&usid®. fhe general pattern Of distribution suggests large cencentratioa® from 65 meters downward. B@ris»tal2y, the euphausid® were found throughout the area of the Strait of Georgia. Prea these data i t can be stated f i r s t , that the population ha® a deeper distribution a® th® aaimals mature and second, that spawning takes place i a late winter or early spring, l a *June, §4^ of the young - 74 ~ had reached the cyrtopia stages* In November* a n the young had reached the adult stage. The adults apparently carry the population through the winter months. 4) Ohaetegnaths. Chaetognaths were found in fairly high concentrations in the plankton samples. A preliminary study showed that at least three species are found in the waters of the Strait. These ares Sa^ltta elegana, Bukrohnia hemata, and faid-tta lyra. The identifioatioa of the speeies was made possible by referring to Lea (1955)* In June* S* elegans feraed the bulk ©f th© ghaetognath population, and was represented by immature as well as mature stages. Imature stages only were found in the supplementary hauls taken ia th© 10-0 and 20-0 asters, end mature individuals wer® taken in 50-0 meter® and deeper. Most of the population wae concentrated in the upper 100 meter®, and was widespread throughout the Strait* Several specimen® of £. haaata were found mixed with j3» elegan®, but they never reached any high preportiom* The quantitat ive distribution of S* ©lagan® was net analysed, but they wer® included ia the total cerofcs* At Stations 5 and IT, two specimen® of j|. Ivrt* w©*© taken in th® deep hauls* This pelagic species had been reported from th© Queen Charlotte Island®, but nowhere else in B.C. waters (Lea, 1954)* and it® presence support® th© evidence that there is an intrusion of oceaniG water into th© basin ©f the Strait through the Strait of Juan d© Fuca. Only two ©haetesnath specie® were found in Sovemberi SajAtt* elegan® and lukreteia haaata* Th© former was taken at ©very station, while the - 75 • latter was recorded only at Station 37* Total count®- of ohaetognaths taken in November indicated no immature individuals but several adults. These were present in a l l samples below fift y meter® (Table VIII) but were generally absent in samples from 10-0 and 20*0 meter®. TABLE VIII Concentration of adult ohaetognaths taken at different depth®, based en a total count of th® animals in each sample. Noveabw 8 - 1 1 , 1955 lumbers of adult ohaetognaths Depth (12 individual samples) (m) 1 2 3 4 5 © 7 8 f l O H 1 2 10 4 6 0 0 0 0 1 0 0 1 0 0 20 10 0 1 7 0 0 0 0 0 50 16 10 15 5 1 43 60 U 65 7 16 100 5 31 34 28 29 22 13 26 54 no '16 150 58 50 30 28 33 22 14 200 20 36 23 230 37 250 50 5) Amphipods. On the whole, amphipods did not form a very conspicuous part of the plankton catches, but their .large size add® significantly to the volume of zooplankton present. Although aapblpoda were found at a n depth®, the center of abundance of insaature forms was situated between 50 meters and the surface whereas th® adults were located in deeperA(Table IX). Total counts wer© made frm the November plankton sample®. - 76 - TABBS M Concentration of adult amphipods taken at different depths, eased on a total count of th© animals in each sample, November 8 - I I , 1955 Depth Cm) 1 2 3 iusfcers of adult amphipods (12 i n d i v i d u a l samples) 4 5 6 7 # 9 10 n 12 10 0 1 0 0 0 0 0 0 0 0 0 0 20 0 0 0 0 0 3 0 0 0 50 2 0 1 0 0 1 60 1 65 0 126 100 11 16 10 10 21 14 2 0 0 110 6 150 35 15 27 15 24 35 7 200 40 34 28 230 41 250 65 The greater abundance of amphipods in the deepest hauls in Wovsanber contrasted with their predominance in June in shallower water* this fact was due to the absence of immature® in the hauls taken in loveaber. 1*& of adult amphipods were found at 65-0 meters and shallower, and 98.2$ were obtained at 100-0 meters and deeper. In the 100-0 meter haul at Station %*?&. amphipods were (following copepods) the most abundant representatives of th® plankton. 6) Gastropods. Although several groups of gastropods form part of the plankton, their small sis® makes them on© of the relatively minor constituents* They include the young spiral-shaped gastropod, larvae, the early clam larvae, and the pteropod larva®, feeept for th® latter group, these gastropod larvae are members of the plankton for a short time. They are next to the appendioularians and euphausida in relative abundance - 77 - in the samples, and are found throughout the Strait of Georgia in the sutmaer and in the autumn, their main distribution i® between 100-20 meters (Table X)»- The group ha® been found at all depth® outside these limits, but net in high numbers. Their distributlen was ubiquitous in June aad November. Gampbell (1929) found them at 75* of the station® in the 100-50 yard, and 30-2G yard haul®. TABLE % Vertical distribution ©f gastropod larvae and eoneeatratlens at • each depth, June & - 16, 1955 Depth ?!«*®f larra® Me.of hauls Apprex.lo.of % of the (a) taken mad® at larvae catch of eaeh depth per haul larvae 10-0 19 1? 1 2. 20-0 71 13 6 6 50-0 123 13 9 11 350-0 407 14 29 37 150-0 316 11 2S 2f 200(*)-0 157 7 22 14 Early clam larvae appeared in small nuafoers at two-thirds of the station®, and their vertical distribution was Identical with that of gastreped larva®. Only else adult ptereped®, were seen i a June, and none were seen i n November. This form i s truly pelagic aad is apparently brought into the Strait by the intrusion ©f oeeani© water through th© Strait of Juan d® Faea. 7) Ostraeods and GIMocerans. Oetraeods and. eladoceraas were among the crustaceans occurring regularly but never in abundance In th© plankton samples examined, fhe former group was found at two-thirds Of the stations in June. Only five mature individuals were caught above 50 meters. The remaining US individuals came from deeper tows. At Stations 20 and 21, ostracods were common but, in contrast to other areas, one-third of the total number of individuals was taken froa a deep haul (200-0 meters) at Station 41* Both immature and mature ostracods were picked up in November* In th® supplementary hauls from 50-0, 20-0, and 30-0 meters, most of the catch consisted of immature individuals, while the deeper hauls contained more adult©. The data obtained could not be used to establish the center of abundance for this group because of the small number of very deep hauls* Ostracods wore ubiquitous in November. Ths immatures accounted for 40$ of the total catch and the adults formed the remaining 60$. It was common during June to pick up a few adult cladoeerans froa the southern regies of the Strait, but none could be found north of the Fraser River* The population was centered around Station 6 in 50-0 meters and the most removed individual was found at Station 22. Tb© cladoeerans were living beneath the diatom population and in th© region of asndan. diatom concentrations, ©akin and Oolefax (1940) have also found clado eerans in greater abundance right at or slightly after a ma^«am phyto plankton bloom, and living beneath the diatom population. During November, three immature cladoeerans and eight adults were found at gt&tion 19A in a 200-0 meter haul. -7? - A) Larva©. Larvae of a l l kinds were very frequently encountered in the plankton catches* Over ninety percent were restricted to three groupst eepeped larvae, barnacle larvae, and crab larvae, lest forms were abundant in June, but rare in November. As a rule, copepod nauplii and metanauplH appeared in greater numbers in 10-0 meters, barnacle nauplii somewhat deeper (50-0 meters)* aad oypris larva© of barnacles at 10-0 waters. Crab larvae were en countered much deeper. The soeal stage was found rarely above 50 meters, and th© metaseeal stage was centered in 100(+)~0 meters (Table XI). TABES U Average numbers of eopeped, barnacle, aad crab larva© caught in each haul, June 8 - 16-, 1?55 Bepta 4-i*"*-',*"'B3 (a) nauplii aetasauplii nauplii eypris aeea aegaleps 10-0 f 4 2 • 1 < 1 < 1 < i 20-0 5 5 3 1 <l <1 < I 50-O 12 8 6. 1 <l 1 <i 100-0 7 8 3 1 <1 1 <i l00<*)-0 f 11 2 1 1 2 <i The cepepod and barnacle larvae were obeerved at every station in varying ©©ncentratiens. The crab larvae were ale© noticed at most of the stations, but always in smaller numbers than copepod and barnacle larvae. Ja addition to the larva© discussed above, « number of other less frequent types were found. These larvae included fish, shrimp, p©3yelmete, - 80 coelenterate, holothurian, and many others. Fw larvae were encountered in November. 9) Diatoms. Since the concentration of diatoms was fairly heavy at the time of the first cruise, and the dinoflageilata concentration was very l i # t , phytoplankton was considered primarily in terms of diatom®. Of the 111 samples collected on the June survey, a l l showed several species of diatoas (see pp. 26 and 2?) whereas during fcvember there was a dearth of diatoms (see p. 31). In spit© of the comparatively large number of species found in June, few species were individually predominant in the samples. Among the forty-six species identified, the following nine were most eonspieuous, both in terms of abundance and regularity of occurrences Skeletmema Jggll*§» I b ^ i ^ Q g ^ .fflrdej-skio.ldli,, mmfcfa B t e y W i semisj M.nft, Blddulphia ljffiii^oruriii, Tfoslas^ sj^ onsma^  n^tssphloldos, Ghasto of the other species taken in June were only found at a few stations, or were represented by scattered individuals. Obsctoodiseus wailssli was th® only genus commonly found in November. It is found at a l l seasons at Oeparture Bay (Gran . and Angst, 1931) * An accurate count ms not possible with the counting chamber used because of the large size of this species, lowever. It could b© observed with the binocular. Ko count was made, but observation of the samples permits describing i t as "common". Johnson (1932) calls i t an important species which is taken freoiaently at Friday Harbor during the late summer and fall months, and totally absent from larch t© July. It was never seen in any of the June samples in the Strait - a - of Georgia. Ita distribution seemed to be ubiquitous* Skeletoneaa The genus Sks^etojaeiiit is represented in the samples examined by ©niy ©ae speeies. Skeletoneaa costatum. Ho other genera of diatoms ex ceeded i t in. abundance in June (Fig. 18). It ©eeurred at a l l th® station® from which samples wer© examined, and most of th® time in very high ©oneen- trations. S. eestatua was responsible for the very high eoneentrations eneountered at Stations 6 and 12 and was predominant in the Hardy Seeorder samples. Jehasoa (1932) mention® that i t i s very abundant at Friday Harbor, and is dsraiaaat at time® in June and July. Gran and Thompson (eg Johnson, 1932) found i t dcsaiaaat in the San Juan Ghsaael ©a June 30, 1930 and between Spieden and Jones Islands ©a July 11, 13, and 22, and in East Sound on August B» The heavy ©eneeatratieas observed i a the Strait of Georgia were not maintained through to lovember, sine® not a single ©ell was eneountered in the f a l l sample®. Thalassioslra The genu® Tbala®®lesira i s represented by three speeies in the sample® exaainedj £• .®m®m$mM» ! • J2M§* ^ d I* SttgBtt$ft* °* these the first was, fey far, the most predominant in both June and lovember. $MSmlMmi m&B&&m. **» in abundance only t© costatum .ia June in th© lardy Seeorder haul®, and the former reached i t s greatest abundanee in a eress-sestion froa Vancouver t© Hanaimo (f i g . 19). In this latter ct*©ss-®®eti@a over a distance of about fifteen mile® j?. nordenskjoldli aad® up ever ©f the catch, and for another ten sCLes i t formed more than 75% of the total yield. Generally spe&klag* th© genus fhalasaieaira came third in abundance* .surpassed only by th© genera Chaeto- ana Skeleteaema. 8* individual species of Ohae^ oeer©® ever ©weeded Fig. 18. Abundance of Skeletonema costatum at 10 f e e t , June 8 - 16, 1955. 8 4 - 1« afffolff«MWVff4* species of Thalassioaira were- nearly always present in fen® vortical haul sample®, and very often T. nordenslAoldii was present in great abundance. . fhe genus Qba#teocero^ < as a whole, is th® most troublesome taxonomically. It was always present, represented by several species, and the chains of cells wsre usually so much twisted ia the counting chamber that identification was difficult and time-consuming. Some specie® could not be identified because of their very small sia® using ordinary methods. On the whole, however* th® more abundant species had characters sufficiently clear-cut to permit identification, fhe three most abundant species were! £. juj^sjtus* £• SgSA&m* « l d £• iS$MM' g* irurvisetus was the species most consistent in appearance for i t occurred .at $0$ of the stations. High concentrations of this latter species occurred Sn the central and. northern region® of the Strait ia June (fig. 20). g. .af.finj.s was fairly regular throughout ths central and northern Strait, but was missing at most of the stations ia the southern. Strait. C. d®ci.plensit had a rather patchy distribution ia the southern and central Straits, but was fairly well represented in th© northers Strait. MitgseM^ The genus Hltgsscfala was pred«isant in June. It was found In large nu^ers in th® vertical haul catches, especially in the deeper hauls. At three meters i t rarely occurred ia high concentrations, suggesting a deeper distribution, fhe only species attaining numerical si^aifleane© ww* MteBS^mmlS& ^M$mMMSmmm* Sometimes one and some-- as ~ tiaea tho other appeared abundant, although size variations make i t difficult in some Instance® to identify to speeies with certainty. For this reason, the speeies were not tabulated separately. Many speeies of fl^M$ftt. occur in deep water at La Jolla in suwer, although this genus i s typically a winter or spring for®. (Allen, jg •Jehnsea, JJ94). Johnson (1932) add® that the winter temperatures at La Jolla ar© separable with the summer temperatures at Friday Barber, where many speeies wer® present at several stations in July, ie assumes that temperatures may constitute th© limiting, faster and that A! the specie® feuad i n ©ar latitude® belong to a different bi©logic"raee than those found further south. The data repeated here seem t® support this argument. It would appear that.summer population® in th® Strait of Georgia belong te th® northern race, although more iaforaatien i s needed, especially over the winter month® to substantiate this claim. It i® possible that th® genus may b© present ^ although unlikely) fellow* lag the lovember period* lepresentatlves ef this genu® were found i a abjwdance an over th® Strait i a June. One species, g« seMsaiaa, was very common, aad another, &• -atolterfethii, was found ©ceasloaaUy* A l l other specie® identified (ft* 1* mMsm&> ^ 1* Mm£S%m) **™ «•* abundant, £ . ser^dspim i® typical ©f the warmer water® of the Strait l a summer. Aeeordiag to Gupp (1943) j|* ®emi»piaa ha® been found .in abundance only i a the Gulf of California* Although i t was not abundant in Hoveaber, i t s ©©surreae® together with it® abuadance in the warmer water® ©f the .Strait l a June suggest a similar situatiest t© that recorded by Oupp - a? - (1943)* Johnson (1932) dees not report ]|. M&m&m in abundance from Friday Harbor when the waters in summer reach higher temperatures. As a rule Johnson (1932) never found the species of Rhigosolenia abundant at any time of the year at Friday Harbor. Bi4#tfeM,a fhe genus Biddulnhia was represented by three species, Bid^lpMa a^^SStHa* 1» teWfo «««I- « ®"ly g. longjcmrif occurred regularly. In fact, i t was universal in distribution, and in June it reached very high ssnee&tratiens. the aeritlc ©editions found in th© Strait of Geor^a seem to account for Its abundance. Allen (1922) and Johnson (lf^2) report that it was new aet with in any considerable numbers at la Jolla and Friday Harbor respectively. Johnson (1932) notes that JU ^ sm&orurlf has been noted in abundance in East Sound, Ores* Island, in Jane, this island is located at the southern end of the Strait. Thalasslonema I l H t e t e l f t rfflMfoW&t. *»* abundant and regular ia distribu tion in June. It was present in more than two-tMrds of the samples and had its maximum concentration ©ff Point Roberts, this genus may have been confused at times with fhalassiothris under the ma^&fioatlw used ia counting. Supp (1943) recognises fhalasslonema as a neritie species very common t*m California to Alaska, whU© he describe® fhal- assiothrix as oceanic and widespread. Johnson (1932) found ThalaesiothriK nearly always present at Friday Harbor althou# seldom abundant. He does not mention thalasslonema at Friday Harbor. Gran and Angst (1931) d© not include fnalasglenema to their record of the diatoms ©ocurriag - m - at Puget Sound* figure 21 shews the percentage distribution at a depth of ten feet of the four most predominant genera along the Hardy Beeorder ©ross-seetiens ( f i g . 1) * Aleut the line A-B, fhalassjesira far ex ceeds a l l other genera, but on a l l other Maes (C-D, B~P, £Wi) gfeele- tonema is more abundant, except in a few localities where ^haetoeeros • J 0 * ffealAssiosim are found in greater number®. Aleag the line 0*© most of the catch is aad© up of Skeletoaema and TimXasaioaira. ahaeteceres values are high only in the first few miles of the tow. Th© line *•? indteates aaeh hitter numbers of Chaeteceres. Where the percentage Of Chaetoceros diminishes for a few miles in the middle of the tew, Thalasj^iesira, replaces i t and shows relatively high concen trations* The last erosa-eectioR, 0-S, is a transition line where o°th S^etenema, aad ,|ha^ag.s|§ej^a have high concentrations. The order of magnitude of the phytepiaalgtoa volumes along th© four cross-sections are presented ia Figure 22. the highest values ar® found opposite Point Robert® on section C-## This are® i s a region ef strong tidal s&xing. On the line A-# values go on increasing frea Point Orey to aabriela Island, but decrease slightly i a the imaediate vicinity of Vancouver Island # latehiasen and Lucas (1931) also observed this phonemes©©. Along the line B-F, values ar© ia very close agreement wit* those ©f Hutehinson aad Lucas* A alight increase is found south «ff Texada Island, but value® g© ©a decreasing northward. The volume® enceuatered around Stations 37 and 38 correspond t© those found at the mouth ef Vancouver iarbour. The line S-B again agrees with th® finding® "5d 25 - 89 - K A L A b S I O S I R A &p. THA L A S S I q NE £ A S p. S K E L E T O N E M A COS T AT U M A 3 9 12 D i stonee 19 18 in miles 21 24 SKELETONEMA iO 15 2 0 25 30 Distance in miles 39 75 % 50 25 \ / \ / V 2JUELE.T0NEMA_ -COSTA TU M CH AET OCE H OS Sp. •THALASSIONEMA sp. THALA&5IQS ! R h Sp. 5 10 15 20 25 30 35 D i s t a n c e in miles 40 *5 75 50 25 SKELETONEMA COSTATUM G 3 Fig.21. 6 9 12 15 18 D i s t a n c e in mites 21 T H A L A S S I O S J R A sp. 24 27 H 4 -91- of Hutchinson and Lucas. Volumes of diatoms increase steadily south ward until they reach their asaimum opposite Point Roberts, they then decrease steadily in the last few miles ef the section, fhe only cross- section which does not f i t in with their results i s the f-sh&ped line opposite the Fraser l i v e r . The values obtained in this cross-section (G-H) are much higher than those found ©a the line A - B . However, knowing the seasonal variation that ean occur both ia phyte plankton abundance and all tb® physical and chemical factor® operative from year to year, i t is not surprising to find some inconsistencies between data reported for 1932, and that obtained ia 1955• - 92 - 1. turlng th® summer when oeeanographi© conditions la the strait ef Georgia vary widely a great variety of organisms is found. Shoeing the autumn* when the waters reach an almost homogeneous state, the number and Variety of forms diminished considerably* In June, over 34 species of copepods, 45 species of diatoms, and 2? other groups of plankton organisms occurred in contrast with 21 species of oopeoods, 5 species of diatoms, and 19 other groups present in Hovember. 2. Three centers of different concentration of sooplaaktom can be recognised and associated with the physical and chemical characteristics of the waters in the Strait of Seorgia. A) aa area of high concentration with warm surface temperatures and strong wiaiag of water masses} B) an area of intermediate concentration with colder surfaee temperatures and little mixing of water masses| 0} aa area of low concentration with s t i l l colder surface temperatures and little mixing of water masses. 3* The number of diatoms found in June: was low «e«pt*s* with the very high values known from some other area® of the world. The data suggest that the sampling may have preceded or followed a period of greater abundance. The waters north of the Fraser liver contained large quantities of 0baet@oeros aad Skeletonema and those south of the Fraser River showed high quantities of ^ halasslosira and Skeletonema. Few diatoms are taken close to the Fraser River estuary, fhe region Is characterised by very low salinities and high turbidity. * 93 - 4» Vertical distribution of zooplankton was apparent and the relative important® of the different groups of plankton organisms varied at 10-© meters, at 20*0 meters* at 50-0 meters, and deeper. Oopepods are grouped into surface forms, sub*surfaee form®, and deep-water forms. Manv more specie® wer® found in th© "upper zone* (50*0 meters) than at greater depth* generally the larval stages inhabited the first few meter® aad the adult® lived at a greater depth. 5. Although th© artber of specie® of geoplankten and phytoplankton was large culy a small number of forms were deainaat, fhe sopapod® MMmismmm ®$®&m* sm^k* MsSm&B* ^ 9mm. *»*>• ««tribut®d 65* of all copepods in June and tmiaS^mM $fcPM*> SUte «P*# ®ad Calanus .finaarchicu® formed 77% of the total number ia lovember. JUL** th® diatom® SM^SBm JggMua* f ^ f e ^ t e m3W*Ms8&b and MSStfaWL «a©e*eu* by far, all other specie® ia June, and ^ osciafdiagu® m&m&l was predeaiaaat in lovember. 6. The rati© of adult male® to female® was, in some copepod speeies, unequal ia- June and Sovember, the males being more abundant at the ©a* set of breeding but later diminishing in nuaber® more rapidly than the female® after th® breeding season* 7. Copepods generally formed the bulk of the ssof&snkUn* fhey were very auwrous in June, but the niwifcers decreased ia Severer. When Juvenile® were very abundant the three dominant sptsios (JmteS&em, ataSSm MM$M l&#*mi*> «*» MMmMsm) responsible. 8. Appa»di©ulari@a® reached a pe&k in June in region® of optimum temperature for this group (12%). I n such area® they far exceeded 94 the cepeped population and dominated the catch. 9. The population of euphauslds Is found t© be distributed v e r t i c a l  l y according t© age. There i s a deeper distribution of the species as the larva® mature. Spawning take® place i n late winter and early spring i n the water of the Strait ©f Georgia. 10. Both Juvenile and adult chaetognaths wer® present i n the June catches. Immature forms wer® found i a th® supplementary hauls taken i n 10-0 and .20-0 meter®» Mature form® ©©curred i n 50*0 meters aad deeper. I© larval forms were found i n lovember. 11. The center of abundance for amphipods lie® between 50-0 «et®rs i n June and below 50 meter® i n Sovember. Th® shallower June distribu tion Is l a i d to the presence ef several immature individuals. 12* Over 90$ ef the larvae caught i n June belonged to %re© group® only* copepod larvae* barnacle larvae* and crab larvae. Gepepod larva© were i n the upper layer (10-0 mete*®), barnacle larvae were found somewhat deeper (50-0 iaeters)» and crab larva® ware encountered much deeper (100-0 meters)* 13. Diatoms were meat abundant areaad a depth of 10 meters. The western portion ef the Strait supported a higher concentration than the colder* less saline eastern portion. The heaviest concentrations ©©curred a l i t t l e south of the Fraser aver estuary in an area of "steep*5 temperature and salinity gradient®• 14. The euryhaliae plankton ©rgaaisas were found in great abundance during June aad lovember 1955* Their distrttJution i a th® Strait ©f Georgia is only slightly affected by the ©©©anagraph!© conditions because - 95 - th© fluctuations i n th© physical arid the chemical characteristics of the water l i e within the limits of tolerance of the organisms, the ©ten©- haUne plankton organisms are limited to the more stable "lower son®" * Within this «l©wer sone" the abundance and distribution of th© steno- hallne forms do not vary very much since temperature© and salinities ar© f a i r l y constant i n space and time, fhe euryhaline heUephylli© forms (diatoms) ar® the most abundant, fhey are found i n regime where fresh water originating fro® the Fraser l i v e r aad salte© water i n the Strait Mx* fhis misdsig process favours pl^ Ftoplankfcoa ataadance to «b . least two ways, fhe mi»d. waters may contain certain physical and chemical factors XmMm In aay one of ti© fresh and sea water masses alone. Also the eatrainmeat of deeper saline water into the upper sone may bring up nutrients where they are available to phytoplankton. -96 - vn»m Allen, W.S. 192®. Catches cf marine diatoms and dlnoflagellates taken by beat i n Southern California waters* Bull* Scripps Inst. Oceanog. JL (13)j 201-246. Bigelow, H*B. and Leslie, M . 1930* Reconnaissance of the waters and plankton of Monterey Bay. BmU. Mas. Comp* Zool. UEZ (5)« 430-5T3. Cameron, A.T. and Mounce, 1* 1922* B&m physical and chemical factors influencing the distribution of marine flora and fauna in the Strait of Georgia and adjacent waters* Gent* Can. Biol* £t 41-70. Cameron, F.E. 1955. Boa® factors Influencing the distribution of pelagic copepod® in the Queen Charlotte Islands area* Masters Thesis, Univ. British Columbia Dept. Zool. (unpubl.). eaapbell, 8*1. 1929. Some fr@#-swimaing copepods of the Vancouver Island region, trans* Soy. So©. Can. XXIII (l)t 303-332. Campbell, M.H. 1934* The life-history and post-embryonic development of th© copepods, Calanus tonsus Brady and Euchaeta .toonioa Marukawa* J . Biol* Board Can* £ (l)s 1-65. Supp, B.E* 1943* Marine plankton diatoms of the west coast of lorth America* Bull* Heripps Inst. Oceanog. £ (1): 1-238. Dakin, W.J. and Colefax, A.N. 1940. The plankton of th® Australian coastal waters off New South Males* Univ. Sydney Publ* Zrnl* Ifcaogr* Is 1-211. Davis, C C . 1949* Th© pelagic copepods of the Northeastern Pacific Ocean* Univ. Wash. Publ. B i o l . 3^ s 1-113. Pawydoff, C f / / / 1923. 1'raite d 'eabryologl© compares? des invertebres. Masson et Cie, Paris* 930 PP« 97 * ^ P ^ S P (eontinued) Bsterly, 0.0. 1905* The pelagic copepoda of. th® San Diego region. Oniv* Calif. Publ. Zool. 2s 113-233* 1926. Th® periodic occurrence of ©opepoda in the marine plankton ©f two successive years at La Jolla, California. Bull. Scripps Inst. Oceanog. 1 (I4)s 247-345• Fraser, CM. 191S. Migration® of marine animals. Trans. Boy. So©. Can. I?i 139-143* Siesbrecht, tr« 1892* Systematik und Faunistik der pelagisohoa Copeeden des Oelfes von fJeapel und der angrenaeaden Meeresabschnitte. Fauna und Flora de® Golfes von Heapel, Menog. XlXr 1-831* Gran, U.U. and Angst, E*C« 1931 • Plankton diatoms ©f Puget Sound. Publ* Puget sound Hoi* Stat. 2« 417-519* Hardy, A*0. 1939* Bcelogioal investigatiea® with th® ©ontinuetta plankton recorder: Object, Plan, and Usthod®. Hun Bull. Kar. Seel* 1 (l)t 1-57* Hart, J.f * 1942* Phytoplankton periodicity in Antarctic surface waters. Disc. Sept. XXIJ 261*356. Hutchiasoa, A*H* If28. A ble-bydrographieal investigation of the sea adjacent to th® Fraser river mouth. Trans* Roy. Soc. Can. XXII (5)» 293-310. Hutehiasen, A.H., Lucas, CO* and ftePhail, M. 1929. Seasenal varlati©®® in th® chemical aad physical properties of the waters of the Strait of Georgia in relation to phytoplankton. Tran®. &®y. Soo. Can. XXIII (5)t 177-183• Hutchinson, A.I. aad Lucas, 0*0* 19J1. The epithalssea of th® Strait of Seergi®. Can* Jour. Be®. £t 231-204* - 9 8 - fCiS (continued) Jespersen, P. and Russell, F.S. 1949- Piehes d'identification du zooplankton. 1952. 0®as» Perm. Int. Expl. Mer 1*50. Gopenhague. Johnson, M.M. 1932. Seasonal distribution of plankton at Friday Harbor, Washington. Univ. Wash. Publ. Oeeaaog. I (l)t 1-38* King, J.E. and Demond, J. 1953* Zooplankton abundance in the central Pacific. Fish. Bull. ,8J (54)t 112-142. lea, H«S* 1955* The chaetognaths ©f western Canadian coastal waters. J. Fish. Ees, Bd. Can. i g (4)t 593-61?. Le Brasseur, E.J. 1955* Oceanography of British Columbia Mainland Inlets. VX. Plaifcton distribution. Prog. aept. Pac. Coast Stns. Can* 10$t 19-21. Lucas, C.C. and Hutchinson, A #8. 192?. A bie-hydregraphle&l investigation of the sea adjacent to the Fraser river m©uth. Trans. Roy. Soc. Can. XXI (5)? 485-520. Marshall, S.M. and Orr, A.P. 1927* The relation of th© plankton to some chemical and physical factere in th© Clyde sea area. J. Mar. Biol. Assoc. B.K« J£i 837-868. Euad, J.T. 1932. Oa the biology of southern Euphausiida®. BvaUradsts Skrifter 2: 1*103. Sars, 0.0. 1903. An account of the Crustacea of Morway* Bergen Jteeum. ^ Copepoda Calaaoida* n/ pp. 1911. Ibid % and 6 Copeped® Barpacticoida. pe Sverdrup, H.U., Johnson, M.W. and Fleming, l.H. 1954. The Oceans. Preutice*iiall. l©6l pp. Tully, J.P. and Dodlmead, A.J. 1954• Properties of the water la Georgia Strait, (unpuhl* manuscript). Wailes, O.H. 1939* Protozoa, le Mastigophora. Can. Pac. Fauna It k5 PP* Wa],diohiik, M. 1952. Oceanography of th© Strait ©f Georgia. 1 .Salinity Distribution* Prog. Rept. Pas. Coast Stns. Can. £|t 26-29* 1953* Ibid. 2 . Temperature Distribution. Prog. Rept. Pac. Coast Stns. Can. 19-23* 1955* Physical Oceanography of the Strait of Georgia, British Columbia. Doctoral Dissertation* Univ. Wash. Dept. Oceanog. (tmpabl.)* Wilson, CB. 1932. The copepods of the Woods Hole Region, Massachusetts. 94. Mat. Mus. Ball. jj5j* 1-625. 

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