180° 



Fig. 3. Distributionof infusoria biomass in the layer of maximum abundance 

 for the Gulf of Anadyr. [Legend: | Biomass in mg/m': 1 ) 790-660; 

 2) 450-330; 3) 280-60. Numbers from 7 to 41 denote stations. 



biogenic elements. The heterogeneous character of the flows 

 makes for an exceedingly complicated picture of 

 microzooplankton distribution in regard to both actual species 

 present and their quantities (Figs. 4—7 ). The species composition 

 and ciliate counts for the western and eastern portions of the 

 Bering Strait differed considerably. Dominant in the east were 

 smaller Strombidia and the Tinnopsis sp. characteristic of less 

 saline water. The bottom layers exhibited degraded algal 

 debris, as was confirmed by chlorophyll a level analysis 

 (1.3 mg/1 in the surface layer and 2.7 mg/1 at the bottom). 

 Species variety and abundance were much greater by the 

 western shore. The presence of heterogeneous flows in the 

 Chirikov basin is evidenced by such things as closely placed 

 Stations 100 and 102exhibitingcompletely different infusoria 

 species mixes. The distinctiveness in question remains in 

 evidence all the way to the neck of the strait (Fig. 7). The same 

 may be said of the quantitative characteristics. The infusoria 

 counts and biomass off Alaska were found to be several times 

 lower than off the eastern coast of the Soviet Union 

 (Figs. 4-7). The biomass in the most abundant layerof the strait 

 ranged from 15 to 1,100 mg/m\ with counts from 2.0 to 

 16.25 X lO^individuals/m'. Thericheststation(Station96) was 

 situated off the western shore, the poorest off the Gulf of 

 Anadyr. Waters within the infusoria-rich stations exhibited 

 high chlorophyll a concentrations (Fig. 7). The same sea areas 

 showed elevated ammonia levels with a maximum of to 



CHUKCHI 

 PENINSULA _/ ^6 



Bering Sea 



■63 



Fig. 



4. Biomass in the layer of maximum abundance for Bering Strait. 

 [Legend:] Biomass in mg/m': 1) 1,100; 2) 280-200; 3) 160-15. 

 Numbers from 83 to 106 denote stations. 



2 mg/m'. The distribution of infusoria over depth in this 

 shallow portion of the sea did not conform to any single pattern. 

 With some stations the density maxima occurred at the surface 

 and at a depth of 10-15 m (Fig. 2). The amount of ciliates at 

 several stations increased considerably with depth, whereas in 

 other instances the distribution with respect to depth was 

 uniform. 



Chukchi Sea 



The sampling station in the southern portion of the Chukchi 

 Sea constitutes a direct extension of the Bering Sea, inasmuch 

 as three distinct flows enter it through the Bering Strait without 

 undergoing much intermingling. These flows come from the 

 Gulf of Anadyr, the Bering Sea Shelf, and the less saline Alaska 

 Coastal waters (Coachman et cil.. 1975). The area in question 

 is shallow, with depths at particular stations ranging from 35 to 

 55 m. Water temperature and salinity vary markedly, the water 

 containing high concentrations of biogenic elements. Against 

 a background of intense algal bloom (Chaetoceros, 

 Thalossiosira. Rhizosolenia, and dinoflagellates), the ciliate 

 community of the Chukchi Sea was quite discrete. It consisted 

 of very large (up to 300-|am long) genus Strombidium infusoria, 

 often of brownish and greenish pigmentation, and very large 

 individuals of genera Cyclothchium. Askeiuisia. Didiniiim. 

 Peritromus, elai. Sucking infusoria (Suctorida)andMe'iW/n/w;?! 

 sp. were quite common. Tintinnida were scarce and few in 

 number (Table 3). Clusters of Chaetoceros socialis often 

 included smaller infusoria and dinoflagellates to fomi a kind of 

 microcoenosis. The numbers and biomass of infusoria were 

 very high throughout the region (Table 4, Fig. 8). In the layer 

 of maximum abundance, the counts ranged from 2.5 to 

 25.1 X 10" individuals/m', and the biomass from 

 85 to 2,330 mg/m\ higher than in the Bering Sea. The highest 



158 



