Made Over a Two Year Period at Stations 15, 25, 50, and 65 Nautical Miles Off Newport, Oregon, Were Examined.Nineteen Species Were Identified

AN ABSTRACT OF THE THESIS OF

Harriet Ann Van Arsdale for the M. S. (Name) (Degree)

-- J - - in Oceanography presented on /'-j '- (Major) ,kD'ate) Title:The Distribution of Hyperiid Amphipods off the Oregon Coast Redacted for Privacy Abstract approved William G. Pearcy

Hyperiid amphipods from one-meter plankton net collections made over a two year period at stations 15, 25, 50, and 65 nautical miles off Newport, Oregon, were examined.Nineteen species were identified. The occurrence of some species off Oregon significantly extended the known geographic ranges.To my knowledge Scina crassicornis burmudensis and Tryphana malmi have not been previously recorded in the North Pacific.Streetsia challengeri, Hyperia hystrix, Lycaea pulex, Qçycephalus clausi, Cystisoma fabricii, and Lanceola loveni have not been reported north of California in the eastern Pacific. The frequency of occurrence of Parathemisto pacifica, Para- phronima graci1is, Hyperia hystrix, Tryphana malmi, and Primno abyssalis generally increased with distance from shore.Average abundance of these species ias usually maximal 50 miles offshore and decreased inshore and farther offshore. Inshore, the largest total catches of hyperiids occurred during the winter, a period when the movement of water was onshore and the heat content was relatively high.Lowest catches and lowest species diversity were found inshore during the summer when upwelling caused offshore movement of surface water.Amphipod catches were compared to the proportion of Subarctic water present,but no consistent relationship was apparent. Vertical distributions of common species were examined. Although catches sometimes varied with depth, evidence for vertical migration was inconclusive. The Distribution of Hyperiid Amphipods Off the Oregon Coast

by Harriet Arm Van Arsdale

A THESIS submitted to Oregon State University

in partial fulfillment of the requirements for the degree of Master of Science June 1967 APPROVED: Redacted for Privacy

Associate Professor ofOceanographK En Charge of Major

Redacted for Privacy

Chairman of Department ofOceanography

Redacted for Privacy

Dean o Graduate School

Date thesis is presented 't21( A9//i Typed by Marcia Ten Fyck for HarrietAnn Van Arsdale ACKNOWLEDGEMENTS

Throughout this study many individuals have given assistance and encouragement for which I am grateful.I want to thank the National Science Foundation (Grant No. GB-1588) for research assistance that was administered by Dr. William G. Pearcy. I particularly want to thank Dr. Pearcy for his assistance, recom- mendations, and encouragement throughout this study. It is a pleasure to acknowledge Dr. Thomas F. Bowman ofthe Smithsonian Institution.His valuable assistance in recommendation of literature and confirmation of species identifications isgratefully appreciated. TABLE OF CONTENTS

Page

INTRODUCTION 1

METHODS AND MATERIALS 2

RESULTS 5 Species Composition 5 Variability of Catches 5 Frequency of Occurrence and Average Abundance of Common Species 12 Seasonal Variation of Common Species 13 Vertical and Diel Variations in Catches of Common Species 16

DISCUSSION 19

CONCLUSIONS 29

BIBLIOGRAPHY 31 LIST OF FIGURES

Figure Page

1 Station locations of collections made off Newport, Oregon. 3

2 The previously reported localities in the North Pacific of hyperiid amphipods discussed in this study. 10

3 The frequency of occurrence and the average abundance of six common species at four stations off Newport, Oregon, from June 1963 to June 1965. 14

4 (a) Seasonal variation of percent Subarctic water 25 miles off Newport, Oregon, from June 1963 to June 1965 between 100 and 200 m.(b) Species composition of monthly catches of hyperiid amphipods and heat content (solid line) in kilocalories percm2 for 100 m depth. Blanks indicate no hyperiids were present. 21

5 (a) Seasonal variation of percent Subarctic water 50 miles off Newport, Oregon, from June 1963 to June 1965 between 100 and 600 m.(b) Species composition of monthly catches of hyperiid amphipods and heat content (solid line) in kilocalories per cm2 for 100 m depth. Blanks indicate no hyperiid were present. 23

6 (a) Seasonal variation of percent Subarctic water 65 miles off Newport, Oregon, from June 1963 to June 1965 between 100 and 600 m.(b) Species composition of monthly catches of hyperiid amphipods and heat content (solid line) in kilocalories percm2 for 100m depth. Blanks indicate no hyperiids were present. 25 LIST OF TABLES

Table Page The Previously Reported Localities in the North Pacific of 19 Species of Hyperiid Amphipods and Their Total Numbers and Frequency of Occur- rence off Oregon in This Study. 6

2 The Means, Standard Deviations, and Coefficients of Dispersion (Level of Significance2. 58) of Individual Species from Five Replicated Vertical Meter Net Collections Taken 50 Miles off Newport, Oregon. 11

3 The Average Abundance per 1000 m3 of Common Species From Inshore and Offshore Stations off Newport, Oregon, During Four Seasons from June 1963 to June 1965. 15

4 Vertical Distribution and Diel Differences of Common Species of Hyperiid Amphipods from 68 Collections 50 Miles off Newport, Oregon. 18 THE DISTRIBUTION OF HYPFRIID AMPHIPODS OFF THE OREGON COAST

INTRODUCTION

Amphipods of the family Hyperiidae are planktonic throughout their existence.They may be important members of the zooplankton community (King and Hida, 1957; McAllister, 1961; Grainger, 1962; King and Iversen, 1962; Raymont, 1963).Amphipods are also important food sources for oceanic fishes (McAllister, 1961; Aron, 1962; Iversen, 1962; LeBrasseur, 1966). Bovallius (1887a) was probably one of the first to compile a systematic list of the Amphipoda Hyperiidea.Stebbing (1888) reported on the amphipods collected by the Challenger Expedition from

18 73-76. In the northeast Pacific, Thorsteinson (1941) reported new species of hyperiids from Nanaimo, British Columbia, and the Gulf of Alaska.The most recent study on the pelagic hyperiid amphipods from the northeastern Pacific was by Bowman (1953).His material was collected from the Columbia River (ca.46° l5'N, 124° W) to Punta Eugenia, Baja, California (ca.27° O8TN, 115° lOW) 40 to 400 miles offshore, and 0 to 140 m in depth.He also examined collections from the Bering, Chukchi, and Beaufort Seas. This report describes the abundance, distribution, and seasonal 440 occurrence of hyperiid amphipods off Newport, Oregon (ca. 39'N, 124° 3'W) from June 1963 to June 1965. 2

METHODS AND MATERIALS

Collections were made off Newport, Oregon, using vertical and oblique one-meter plankton net tows.All nets had a mesh aperture of.571 mm. A Tsurumi flow meter in the net opening provided estimates of the volumes of water filtered. Collections made from June 1963 to June 1965 at stations 15, 25, 50 and 65 nautical miles offshore were examined (Figure 1). Before January 1964, 18 oblique tows were made with a net eight to nine meters in length, towed four to six knots, descending at 50 m per minute and ascending at 30 m per minute.After January 1964 all tows were vertical, using a net four meters in length, descending at 50 m per minute and ascending at 30 m per minute.All oblique and vertical collections were taken at night to a depth of 200 m (depth permitting).A total of 58 collections was made. Sixty-eight special collections made 50 miles offshore during both day and night were also examined.These collections were taken with tandem close-open-close meter nets that were actuated by pressure-activated wire cutters (Yentsch, Grice, and Hart, 1962). The tandem nets, towed obliquely, sampled the approximate depth intervals of 0 to 150 m, 150 to 250 m, 150 to 450 m, 450 to 600 m, 450 to 1000 m, and 600 to 1000 m.Only the 0 to 150 m and 150 to 450 m intervals were examined for hyperiids. I I WASH.

.ASTOø

6550 2515 ; I I WPORT

440 I

009 BAY

-430

0 29 - NAUTICAL MILES -

kRooKuios ORE :. CAL..

Figure 1.Station locations of collections made off Newport, Oregon. 4

Samples were preserved in 10% formalin aboard ship.In the laboratory hyperiid amphipods were sorted from the whole sample if they numbered less than 200.If they were more numerous, the whole sample was divided by a Folsom Plankton Splitter (McEwen, Johnson, and Folsom, 1954) until about 200 hyperiids remained in the aliquot. The abundance of each species was determined by relating the number observed in each sample to the volume of water filtered. 5

RESULTS

Species Composition

A total of 19 species of hyperiid amphipods werecollected off Newport, Oregon.They are listed in Table 1 along with previously reported localities in the North Pacific.Also listed for each species are the total number collected offOregon, and the frequency of occurrence (percentage of collections inwhich the species was found). The previously reported localities of each species inthe North Pacific are shown in Figure 2.To my knowledge Scina crassicornis burmudensis and Tryphana mairni have not been previouslyreported in the North Pacific.Streetsia challengeri, Hyperiaystrix, Oxycephalus clausi, Cystisoma fabricii, and Lanceola lovenihave not been reported from the eastern Pacific.Lycaea pulex has not been reported north of about33° 30'N.

Variability of Catches

Five replicate vertical meter net tows, made 50 milesoff New- port, Oregon, were studied to show sampling variability.The means standard deviations, and coefficients of disperson of individual species are listed in Table 2.Catches of each species were low; some species were frequently absent from the collections.The coefficients 6

Table 1.The Previously Reported Localities in the North Pacific of 19 Species of Hyperiid Amphi- pods and Their Total Numbers and Frequency of Occurrence off Oregon in ThisStudy.

TotaL NumberPrequency of Previously Report1 Localities Collected off Occurrence (%) Species in the North Pacific Oregon off Oregon Parathernisto pacifica Between Japan and the Sandwich Islands 4260 51 Stebbing, 1888 35° 20'N, 153° 39'E (Stebbing, 1888). Subartic water from about 500 N, 170° E (Bowman, 1960).

Iraphronima gracilis Northern temperate and tropical regions 2696 44 Claus, 1879 (Bovallius, 188Th).36° 42'N, 179° SOW; 36° 23'N, 1740 31.'E; 350 41'N, 157° 42'E; Api (New Hebrides 23° N, 168° E) to Cape York (North Australia 9. 5° S, 142. 5° E); 7° 17'N, 147° 20'W (Stephensen, 1918).Columbia River tolower Baja, California (Bowman, 1953).Santa Catalina; San Pedro Channel; Point Fermin; Punta Rompiente; San Nicolas Basin; Michoacan, Mexico (Hurley, 1956).

Streetsia challengeri 35035'N, 150° 50'E (Stebbing, 1888). 1227 34 Stebbing, 1888

Typhana malmi Boeck, None 824 29 1870

Hyperia hystTix Sea of Japan 39°N, 133°E North Pacific 233 18 Bovallius, 1887 about 46°N, 165°E (Bovallius, 188Th).

Phronima sedentaria 36° 23'N, 174° 31'E; 13° 11'N, 139° 174 18 Forskal, 177S 28'E 35° 1l'N, 139 28'E (Stebbing, 1888).Point Loma; Point La Jolla; North Coronado Island; Catalina Island; Monterey Bay (Holmes, 1909).Gulf of Alaska; coast of California; wide distribution throughout the Pacific (Thorsteinsion, 1941).Santa Catalina; San Pedro Channel; Rompiente; San Lucas; Michoacan, Mexico (Hurley, 1956).

Primno abyssalis Gulf of Alaska; Nanaimo, British 626 17 Bowman, 1953 Columbia; Columbia River to below Point Conception, California (Bowman, 1953) 7

Table 1.Continued.

Vibilia armata 300N to about 25° S (Stephensen, 1918). 554 15 Bovallius, 1887 Widely distributed in eastern Pacific from about 44° N to 35° S (Bowman, 1953). San Pedro Channel; Point Fermin; San Nicolas Basin; Punta Rompiente; San Lucas; Santa Catalina (Iurley, 1956).

Hyperoche medusarum Monterey Bay (Shoemaker, 19a). Sea 577 13 KrØyer, 1923 of Japan (Behning, 1939).Gulf of Alaska (Thorsteinson, 1941).Eastern Pacific from Monterey Bay to Punta Eugenia, Baja,California (Bowman, 1953).San Nicolas Basin (Hurley, 1956).

Paraphronima crassipes Tropical region Bovallius, (188Th). Columbia15 06 Claus, 1879 River in Punta Eugenia (Bowman, 1953). Santa Catalina; San Pedro Channel; Point Ferrnin (Hurley, 1956).

Pimno macropa Nanaimo, British Columbia; Gulf of 44 04 Guerin, 1836 Alaska (Thorsteinson, 1941).Columbia River to Punta Eugenia, Baja, California; Bering, Okhotsk, and Japan Seas (Bowman, 1953).Point Ferrnin; San Pedro Basin; Santa Catalina (Hurley, 1956).

Dairella caljfornica Off the coast of southern California 35 04 Bovallius, 1885 (Bovallius, 1887a).Northern temperate and tropical regions off the west coast of California (Bovallius, 188Th).Columbia River to Punta Eugenia, Baja, California (Bowman, 1953).

Lycaea pulex Santa Catalina Island (Hurley, 1956). 5 03 Marion, 1875

Oxycephalus clausi Between Japan and Honolulu 6 03 Bovallius, 1887 (Stebbing, 1888).27° 30'N, 122° 50'E (Stephensen, 1918).

Vibilia propingua Off Volcano Island 25° 30'N, 138°E 9 02 Stebbing, 1888 (Stebbing, 1888).Columbia River to lower Baj a, California (Bowman, 1953). Table 1.Continued.

Vibilia wolterecki Sea of Japan; Columbia River to Punta 13 02 Behning, 1939 Eugenia, Baja, California (Bowman, 1953).

Cystisoma fabricii Indo-Pacific (Zanzibar and East Indies) 5 02 Stebbing, 1888 40N to 100 S (Barnard, 1932).Point Ferniin; San Nicolas Basin; south coast of Santa Catalina (Hurley, 1956). 490 Lanceola loveni KurU-Kamchatka Trench 26 'N, 3 01 Bovallius, 1885 158° 42'E 49° 48'N, 157° 45'E 430 44', 149° 44'E; 430 19'N, 157° 46'E (Vinogradov, 1957).

Scina crassicornis None 1 01 burmudensis Shoemaker, 1945 Species Legend

1. Parathemisto pçifica 10.Primno macropa 2.Paraphronima gci1is 11.Dairella californica 3.Streetsia challengeri 12.Lycaea pulex 4.Hyperia hystrix 13.Oxycephalus clausi 5.Phronima sedentaria 14.Vibilia propingua 6.Primno abyssalis 15.Vibilia wolterecki 7.Vibilia armata 16.Cystisoma fabricii 8.Hyperoche medusarum 17.Lanceola loveni 9.Paraphronima crassipes

Figure 2.The previously reported localities in the North Pacific of hyperiid amphipods discussed in this study.Insert is enlargement of the eastern Pacific from Vancouver Island to Baja, California. (Dashed lines indicate reported localities. '-I 1 \\ I 2 ,ot, ';- $ S N ® ,oz .il O9 .06 Ot .'JI Table 2.The Means, Standard Deviations, and Coefficients of Disperson (Level of Significance=2. 58) of Individual Species from Five Replicated Vertical Meter Net Collections Taken 50 Miles off Newport, Oregon. Replicate Coefficients Collections Standard of Species I II III IV V Means Deviations Dispersion Hyperoche medusarum 0 3 2 0 1 1. 2 1. 31 1.43

Oxycephalus clausi 0 0 0 1 0 . 2 .45 1.01 Paraphronima gracilis 0 2 0 4 4 2. 0 2. 00 2. 00 Parathemisto pacifica 8 2 3 0 4 3. 4 2. 97 2. 59*

Phronima sedentaria 0 1 0 0 0 . 2 . 45 1.01

Primno abyssalis 2 1 0 0 0 . 6 .89 1.32

Streetsia challengeri 2 4 2 3 3 2. 8 . 84 . 25 Tryphanamalmi 6 0 0 2 1 1.8 2.49 3.44*

Vibilia wolterecki 0 1 0 1 0 . 4 . 55 . 76

* Significant 12 of dispersion for two species, Parathemisto pacifica and Tryphana malmi, were significantly higher than that expected for a random distribution (Holme, 1950) indicating a patchy distribution.The coefficients for all other species were less than the level of significance, but the data are too meager to conclude anything definite about spatial distributions. Comparisons of the catches of amphipods from oblique tows (1963) and vertical tows (1964-65) indicated that average abundance was generally slightly higher in the oblique than in the vertical at all stations, except 25 miles offshore where the average numbers of species per tow were equal.This difference may have occurred be- cause more water was filtered in the oblique tows (McGowan and Fraundorf, 1966).However, the difference in abundance and diversity for the two types of collections were usually small and probably resulted from sampling variability, temporal changes in species abundance, and/or differencesinoceanographic conditions from year to year.For example, 1963 was warmer than 1964 or 1965.

Frequency of Occurrence and Average Abundance of Common Species

Of the 19 species the following six were found in abundance and will be discussed in detail: Parathemisto pacifica, Paraphronima gracilis, Streetsia challengeri, Hyperia hystrix, Tryphana malmi, 13 and Primno abyssalis. The frequency of occurrence of the common speciesgenerally increased with distance from shore (Figure 3).Five of the six species showed highest occurrence 65 miles offshore.The exception, Streetsia challengeri, occurred in higher numbers50 miles offshore.Parathemisto pacifica and Hyperia hystrix decreased in occurrence from 15 to 25 miles offshore andthen increased to 65 miles offshore.Primno abyssalis was absent inshore. Whereas the frequency of occurrence of common species was usually highest 65 miles offshore, their average abundance was usually highest 50 miles offshore and lowest l5or 25 milesoffshore. PrimnQ abyssalis, the only exception, was most abundant65 miles offshore.The abundance of Parathemisto pacifica, Paraphronima gracilis, and Hyperia hystrix was lowest at 25 miles offshoreand increased shoreward.

Seasonal Variation of Common Species

The seasonal variation of common species is shown in Table 3 for inshore and offshore stations.Inshore stations were located 15 and 25 miles, and offshore stations 50 and 65 miles off Newport,

Oregon.The four seasons were designated as follows: spring, March-May; summer, June-August; fall, September-November and winter, December-February. 14

tOO 80

E______Parothernisto pocifica 0 o so

: TT7T ?I!P graolss m phrontma qracilis

100 z z 50 40

° 0 O challengeri Streetsla chaflengeri 0 Streetsia z0 tOO . 80 IL a 0 z 50

c_) 0 , w______z Hyperia hystrix yp hystrix

a tOO c 80 Iii >LU Li.. 40

0 0 ]phano malmi Tryphana malmi

100 80

0 Primno qyssaIis Primnogyssahs

0 15 25 50 65 0 15 25 50 65 NAUTICAL MILES FROM SHORE Figure 3.The frequency of occurrence and the average abundance of six common species at four stations off Newport, Oregon, from June 1963 to June 1965. 15

Table 3.The Average Abundance per 1000m3of Common Species Fom Inshore and Offshore Stations off Newpor; Oregon, During Four Seasons from June 1963 to June 1965. Blank Spaces Indicate No Samples Were Taken.

13 1964 1965 Inshore Offshore Inshore Offshore Inshore Offshore Parathemisto pacifica spring 25. 50 46. 75 20. 00 4. 00 summer 0 168. 16 42. 25 66. 25 25.00 fall 94. 60 15. 00 36. 50 34. 66 winter 15. 33 70. 00 21.50 63.00

Primno abyssalis spring 0 6.50 0 2.66 summer 0 0 0 13.75 0 fall 0 0 0 0 winter 0 1. 66 0 6. 33

Paraphronima gracilis spring 75. 00 7. 50 3. 75 12. 00 summer 0 97. 50 0 8. 25 0 fall 0 53. 75 26. 00 6. 66 winter 25. 66 45. 00 14. 00 14. 66

Seetsia challengeñ spring 0 0 0 4.66 summer 4. 50 35. 50 0 1. 50 0 fall 4. 20 18. 00 0 0 winter . 33 203. 16 0 15. 00

Hyperia hystrix

spring 0 6. 75 . 50 5. 66 summer 0 6. 16 0 0 3.00 fall 35. 20 14. 25 0 7. 00 winter 3 33 33. 00 0 4. 66

Tryphana malmi spring 17.00 3. 50 2. 25 0 summer 0 3.33 0 0 0 fall 7.60 21.00 10.00 18.66 winter 10. 83 47. 50 0 25. 00 16

Inshore, Parathemisto pacifica andHyperia hystrix were highest in abundance during the fall of1963,and Paraphronima gracilis and Tryphana malmi were highest duringthe winter.In1964Para- phronima gacilis and Tryphana malminumbers were highest in the spring; Parathemisto pacifica washigh in abundance in all seasons.

Offshore in1963Parathemisto pacifica and Paraphronima gracilis were highest in abundanceduring the summer; Streetsia challengeri, Hyperia hystrix, andTryphana malmi were highest in abundance during the winter season.In1964Parathemisto pacifica and Primno ayssa1is werehighest in number during the summerand Paraphronima gracilis, Streets ia challengeri,and Tryphana malmi were most abundant duringthe winter. In all seasons of1964Primno abyssalis, Streetsiachallengeri, and Hyperia hystrix were absentinshore. In summary, the greatest abundanceinshore was generally during the fall and winter months in1963and in the spring of1964. Offshore the greatest abundance wasmainly during the summer and winter months of1963and1964.

Vertical and Diel Variations in Catches of Common Species

Data on vertical distributions andday-night differences of the six common species provided by meter netcollections are presented 17 in Table4. No significant statistical differences in dielabundance were evident, but comparison of day samples from0-150m and 150-450 m and night samples from the same depths did indicateseveral significant differences (P <. 05) in vertical distribution(Table 4). Parathemisto pacijç, Paraphronima gracilis, andTryphana malmi were most abundant in the0-150m samples during the daywhile Primno abyssalis was more abundant in the150-450m collections.

In the0-150m tows taken at night Streetsiachallengeri and Para- pronima gracilis were abundant; in the150-450m depth interval Primno abyssalis was most abundant.Thus, trends indicating vertical migration of the common species were notevident. 18

Table 4.Vertical Distribution and Diel Differences of Common Species of Hyperiid Amphipods from 68 Collections 50 Miles off Newport, Oregon. Diel Vertical 0-.lSOm 150-450m 0-iSOm150-450 0-150 150-450 day nightdaynight day day nightnight Parathemisto pacifica mean 9. 64 51. 122. 8 2. 5 9. 642. 8 51. 122. 50 standard deviations11. 93106. 254. 876. 80 11. 934. 87106. 2 6. 8 t 1.2 .09 2.098* 1.57 frequency of

. . . occurrence f.o. . 63 94 .46 .50 .63 .46 94 50

Streetsia chalengeri 12. 73 13. 942. 40 .67 12. 732. 4 13. 94 . 67 s 25.4719.046. 161. 78 25. 476. 16 19. 041. 78 39* t 12 . 29 1. 54 2. f.o. .54 .70 .33.16 .54 .33 .70 .16

Paraphronima gracilis 11. 50 28. 112. 503. 08 11. 502. 50 28. 113. 08 14. 02 36. 262. 964. 54 14. 022. 96 36. 264. 54

t 1.32 . 38 2.44* 2.36* f.o. .68 .94 .60 .41 .68 .60 .94 .41

Primnoabyssalis

. 3. 40 . 889. 207. 33 3. 409. 20 887. 33 6. 33 2. 35 7. 956. 67 6. 337. 95 2. 356. 67

t 1. 16 . 32 2.47* 3 79* f.o. .31 .17 .80 .75 .31 .80 .17 .75

Tryphana malmi 5.41 3. 24 . 801. 50 5. 41 . 80 3. 241. 50 6. 91 3. 64 1. 642. 76 6. 911. 64 3. 642. 76

t . 86 . 56 2.55* 1.46 f.o. .54 .64 .26.41 .54 .26 .64 .41

Hyperia hystrix 3. 86 1. 882. 732. 92 3. 862. 73 1. 882. 92 s 12. 34 3. 862. 604. 70 12. 342. 60 3. 864. 70 t .24 .09 .35 .65 f.o. .31 .29 .80.50 .31 .80 .29 .50

* Significant on the.05 level. 19

DISCUSSION

The ocean off Oregon is transitional in character,being influenced by the California Current, Davidson Current, andseasonal upwelling. The California Current is the southerly flowingextension of the North Pacific Drift, the name being specifically applied tothe portion of the current 700 km offshore between480and230N (Sverdrup, Johnson, and Fleming; 1946).This current is the main source of Pacific Sub- arctic water that has been shown by Tibby(1941), Fleming (1958), and Rosenberg (1962) to be the predominant water massoff Oregon. Changes in the prevailing atmospheric circulation producemajor seasonal changes in ocean circulation.Upwelling of the surface water occurs mainly during the summer in responseto northern winds. During the winter the movement of surface water is onshore,due to the prevailing southwesterly winds.Between October and March a warm northward flow called the DavidsonCurrent develops along the Oregon coast.Using returns from drift bottles, Burt and Wyatt(1964) found this current to reflect the local wind stress on the water sur-

face. The frequency of occurrence of the common species of hyperiids generally increased from the inshore to the offshore stations (Figure 3). The average abundance usually increased from 25 to 50 miles offshore and then decreased (Figure 3).The percentage of Subarctic 20 water within the upper 500 m generally increasedin a seaward direction toward the California Current (Tibby, 1941; Rosenberg,1962; Pattullo, unpublished).The similar trends of frequency of occurrence and percent Subarctic water in theoffshore environment sug- gested a possible correlation between percent Subarctic waterand occurrence and abundance of hyperiids. The seasonal catches of hyperiids and the seasonal variations of the Subarctic Water from 100 to 500 m were plotted (Figures 4,5, and 6).The method used to find percent Subarctic water was discussed by Tibby (1941) and assumes that water masses of intermediate character are formed by the mixing along surfaces of Sub- arctic and Equatorial waters.In 1963 upwelling was not well developed, as shown by the low values for percent Subarctic water above 300 m compared to those present in 1964 when upwelling was developed (Figures 5 and 6).In 1964 the 70% isopleth was present above 200 m atthe station 50 miles offshore and the 65% isopleth was present to about 100 m at the station 65 miles offshore.Inshore, the isopleths were not continuous due to the shallow sampling depth(Figure 4). No obvious positive correlation was found between hyperiid abundance and Subarctic water (Figures 4,5, and 6).In fact, the opposite was more often the case.For example, at 50 miles offshore the highest percent of Subarctic water above 300 m occurred during July 1963 and 1964, yet the catches of amphipods were low during these 0 E (0) - 100 I-. 0. 200 0w ?H

11i (b) porat Pit Parhroi'tma qrocths 70 '4 Tryphonamalrrä Ill Streetiacflalienqeqi 60 12

50 o o z 0 Ir'i 40z -S 4 30 LU C, 20 C, z 3 10 a

rS1.--.S'Ls.]i ft1 F-r- I 0 0 J JASON DJ F MA U JJ A SO NO JF MA U J J /963/964 /965 MONTH Figure 4.(a) Seasonal variation of percent Subarctic water 25 miles off Newport, Oregon, from June 1963 to June 1965 between 100 and 200 m.(b) Species composition of monthly catches of hyperiid amphipods and heat content (solid line) in kilocalories per cm2 for 100 m depth. Blanks indicate no hy-periids were present. Figure 5.(a) Seasonal variation of percent Subarctic water 50 miles off Newport, Oregon, from June 1963 to June1965 between 100 and 600 m.(b) Species composition of monthly catches of hyperiid amphipods and heat content (solid line) in kilocalories per cm2 for 100 m depth. Blanks indicate no hyperiids were present. 100 0 E 300200 I-0 400500 600 24

22 20 18

16 23 (a) 6O

0 I4 120 -_ 12 6 110100 MONTH 8090 6070 m 50-4 z 2040 n rr) 3a N I00 Figure 6.(a) Seasonal variation of percent Subarctic water 65 miles off Newport, Oregon, from June 1963 to June 1965 between 100 and 600 m.(b) Species composition of monthly catches of hyperiid amphipods and heat content (solid line) in kilocalories per cm' for 100m depth. Blanks indicateno hyperiids were present. Li] w- I 300 C 500600

700

800 IS

16 (a)

00 E 1214 25

'I, gpo 65 N_Th / 70 70 N [IJ (0 1\ I iI'=Pii - 80 I MONTH rnmiI -- 6070 -4 P1 r.r 0 z -4 40 Z -4P1 2030 0 [i to N 26 periods (Figure 5).Similarly, a direct relationship between hyperiid catches and percent Subarctic water was not evident65 miles offshore (Figure 6).The isopleths of Subarctic water at this station varied little, and the average monthly abundance of hyperiids was more uniformBut highest catches of amphipods were often made when the percent Subarctic water was decreasing or at intermediate

values. The abundance of one species, Primno abyssalis, was correlated with a high percentage of Subarctic water.This species was most common offshore during the spring and summermonths (Table 3), a period when percent Subarctic water was usually high (Figures

5 and 6).Bowman (1953) also found that this species was indicative of Subarctic water. To show possible relationships between the abundance of hyperiid amphipods and the amount of heat, catches of the common species were plotted against the heat content for each station(Figures 4,5,

and 6).The heat content for a column of water onecm2and 100 m in depth has been computed by Kuim and Pattullo (in preparation) at stations 25, 50, and 65 miles off Newport, Oregon.The high amount of heat present from May through September1963, the usual period of upwelling off Oregon, is further evidence that upwelling was not well developedIn 1964 the heat content was low during the upwelling period.The low value in February 1965 could 27 possibly be due to advection of cold water from the north, little or no development of the Davidson Current, or in situ cooling. The abundance of hyperiids 25 and 50 miles offshore was low when heat content was low.Sixty-five miles offshore, however, when the heat content was high, abundance was high, and as the heat content decreased, abundance decreased.In 1964 and 1965 upwelling was evidenced by the low heat content from May through September. During these years abundance 25 and 50 miles from shore appeared to be low when the heat values were minimum and high when heat content values were maximal.Sixty-five miles from shore highest abundance occurred when the heat content was at a minimum.There- fore, no simple or consistent relationship between heat content and abundance is evident. The lower abundance and frequency of occurrence inshore (Figure 3) and the higher variability of catches inshore than offshore (Figures 4,5, and 6) suggest that most of the species of hyperiids are offshore-oceanic species.Thus the numbers inshore may be affected by seasonal changes in advection in an offshore to inshore direction.During the period of upwelling the catches inshore were usually low.This may be caused by the offshore movement of surface water resulting from northerly winds.With the change in the wind regime from a northerly to a southerly direction there was an onshore movement of surface water from November through February (Burt and Wyatt, 1964).It was during this period thatthe occurrence and abundance ofthe hyperiid amphipods were usually at a maximum inshore.Therefore, the movement of surface water may possibly be correlated with the inshore occurrenceof the hy-periid amphipods.Hebard (1966) found that the speciescomposition of euphausiids and copepods was also most similarbetween these stations during the winter. 29

C ONCL tJSIONS

1. Nineteen species of hyperiid amphipods werecollected off

Oregon.Of these, six were common: Parathemisto pacifica, Paraphronima gracilis, Streetsia challengeri,ypJ hystrix, Tryphana malmi, and Primno abyssalis.

2. To my knowledge Scina crassicornis burmudensisand malmi have not been previously reported in theNorth Pacific.The species Streetsia challeneri, jperia hystrix, Oxycephalus clausi, Cystisoma fabricii, and Lanceolaloveni have not been reported from the eastern Pacific;Lycaea pulex has not been reported north of about33° 30'N.

3.The frequency of occurrence of common speciesof hyperiids usually increased seaward reaching a maximum value65 miles offshore.The abundance usually reached a peak 50 miles fromshore.

4.Seasonal fluctuations of hyperiid abundance were more pro- nounced inshore than offshore.The abundance of hyperiid amphipods was maximal inshore during the winter.

5. Examination of water movement and inshore abundance showed that abundance was high during the period of onshore movement and low during periods of offshore movement.

6.Comparison of percent Subarctic water with abundance showed no consistent relationship.However, Primno abyssalis was usually 30 present only when the percentSubarctic water was high.

7.There was no positive evidenceindicating vertical migration of hyperiid amphipods.The greatest abundance of hyperiids wasin the 0-150 m depth interval. BIBLIOGRAPHY 31 Aron, W. 1962.The distribution of animals in the eastern North Pacific and its relationship to physical and chemical conditions. Journal of the Fisheries Research Board of Canada 19(2): 271-314. Barnard, K.H.1932.Amphipoda. Discovery Reports 5: 1-326. Behning, A. 1939.Die Amphipoda-Hyperiidea der den Fernen Osten der Ud SSR ungrenzenden Meere. Internationale Revue der gesamten Hydrobiologie und Hydrographie 38: 35 3-367. Bovallius, C.l887a.Systematical list of the Amphipoda Hyperiidea. Bihand Till Svenska Vetenskaps-Adademiens Handlingar 11(6): 1-48.

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