1 



168°W 



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15 







70°N 

 15 



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-69° N 



19 



1 6t|°W 



15 



10-FATHOM LINE 



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168°W^ — ^ / 



APPROXIMATE BOUNDARY OF 

 HIGH SPECIES DIVERSITY AREA 

 APPROXIMATE BOUNDARY OF 

 LOW SPECIES DIVERSITY AREA 



Figure 1. — Station locations (circled numbers) at which zooplankton samples were taken by the USCG 

 icebreaker G/aciVr in 1970 and b_v the USS /Verfui (prefix N) in 1947 and the number of species collected at 

 each station (numbers without circles). 



Glacier, 47 were for hydrographic casts; I was able to 

 sample at 39 of those stations. At each station two 

 samples were usually taken within 5 min of each other. 

 All sampling was done with a 0.5-m diameter No. 

 (0.57 mm) mesh NorPac standard net. The net was 

 lowered to 2 m from the bottom over depths of 1 8 to 5 1 

 m and was retrieved vertically at 40 m per min. The 

 samples were preserved with 5% formaldehyde solu- 

 tion in plastic bags immediately after they were col- 

 lected. Counts and identifications of zooplankters 

 were done at the Auke Bay Fisheries Laboratory. No 

 subsampling was required because the number of zoo- 

 plankters in each sample was generally low (9-1,900). I 

 did not make an extensive literature search for the 

 most recent taxonomic revisions and was able to iden- 

 tify many of the larvae and even some of the adults 

 only to phylum, class, or order (Table 2). 



Biomass of the samples was not measured because 

 weight measurements (wet or dry) and oxidation tech- 

 niques would have made the specimen unfit for further 

 taxonomic study; volumetric measurements were pre- 

 cluded by the large numbers and the large size varia- 

 tion of the hydromedusan^^/flA?r/?a digitale. 



I assumed a net efficiency of 100% and converted 

 the catch data to numbers of zooplankton per 100 m^ 

 of water filtered. The coarse mesh (0.57 mm), short 

 vertical tows, and absence of noticeable clogging by 

 phytoplankton make the 100% assumption reasonable. 



The review of field and laboratory studies of the ef- 

 ficiencies of the plankton nets by Tranter and Smith 

 ( 1968) indicates that the actual volume of water filtered 

 by slowly pulled coarse mesh nets is no less than 95% 

 of the theoretical. 



Tiie abundance of the eight most common zooplank- 

 ters (A- digitale, Clione limacina, Sagitta elegans, 

 Aiartia longiremis, Calanus finnuirchicus, Centro- 

 pages abdomiiuilis. Eiicalaniis hiingii. Pseudocalanus 

 miniitiis) and all calanoid copepods combined were 

 examined for correlations with hydrographic condi- 

 tions by comparing contour charts of levels of abun- 

 dance of each species and total calanoid copepods 

 with the contour plots of temperature, salinity, and 

 dissolved oxygen from Ingham and Rutland (1972). 

 Values of A'' (A" = 3, 4, or 6; / = 1, 2, 3, . . .m) were 

 used to assign levels of abundance of each group at 

 each station. I contoured areas of absence and pres- 

 ence, and arbitrarily subdivided presence into five 

 categories of abundance. Because a single scale of 

 abundance could not be reasonably applied to all 

 species, a separate scale based on maximum abun- 

 dances recorded during the cruise was used for each 

 species. To avoid subjective judgments. I used the 

 power function to delimit abundance categories. This 

 choice of power function was justified partially by the 

 ease of computation and partially by the need to 

 counter the effect of increasing variance with increas- 

 ing means. 



