characterized by a very special species mix that includes 

 numerous larger species. A particular microcoenosis was 

 found to occur within Chaetoceros clusters. Also dominant 

 were species of the genus Strombidium. The two seas differed 

 considerably with respect to species structure. 



The level of ciliate development in the Bering and Chukchi 

 Seas is very high. The maximum biomass in the former case 

 was noted in the East Polygon and in the Bering Strait ( 1 .22 and 

 1.10 g/m\ respectively). Studies conducted in 1981 yielded 

 similar values. The infusoria community in the Chukchi Sea 

 developed no less intensively, with maximum biomass assays 

 exceeding even those of the Bering Sea. 



A positive correlation was noted between ciliate biomass 

 and chlorophyll concentration. Areas with very abundant 

 ciliates showed elevated ammonium levels. These levels are a 

 result of metabolic activity. Developing as intensively as they 

 do, ciliate protozoa play a major role in plankton community 

 metabolism in both seas. Thus, in the layer of maximum 



abundance averaged over the whole of the Bering Sea, they are 

 capable of involving 1 .5 g of primary and bacterial production 

 per cubic meter of water per day in the food chain, yielding 

 0.5 g of product per cubic meter over the same period. In the 

 Chukchi Sea with a total biomass of 600 mg/m' in the layer of 

 maximum abundance, the corresponding figures are 2 g of 

 organic primary nutrient and 1 g of production, respectively. 

 The findings of the present study indicate that infusoria are 

 reliable indicators of the hydrological and hydrochemical 

 characteristics of seawater. Thus, in the straits in the southern 

 portion of the Bering Sea, we noted infusoria species that 

 pointed to the connection with Pacific Ocean water. Distinct 

 water masses passing through the Bering Strait are characterized 

 both by distinctive species mixes and differing quantitative 

 characteristics. 



The author is grateful to engineer O. N. Le vina of the Oceanology 

 Institute of the USSR Academy of Sciences ( Southern Branch) for her 

 contribution to the present study. 



5.2.2 Characteristics of Zooplankton 

 Communities 



ANDREY S. KULIKOV 



Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences, Moscow, USSR 



Introduction 



The Third Jomt US-USSR Bering & Chukchi Seas 

 Expedition, on board the research vessel (RA^) Akademik 

 Korolev (July-August, 1988), carried on investigations of 

 mesozooplankton of the Bering Sea that had been started in 

 1 977 on the Second Joint US-USSR Bering Sea Expedition on 

 the RA' Volna (Izrael, 1983). During the 1988 expedition, 

 investigations of mesozooplankton of the Chukchi Sea were 

 also carried out. Along side previously investigated sampling 

 areas East, North, and South Polygons (expeditions of 

 Kolosovaefa/., 1987; Kulikov. 1990), sampling stations in the 

 Anadyr Bay, the Chirikov basin, and Bering Sea were 

 investigated. 



Materials and Methods 



Samples of mesozooplankton were collected with 30-1 

 Niskin bottles and, at the same time, at the majority of stations, 

 with Big Jedy net (BJN) with 37-cm inlet diameter and filtering 

 cone (168-mm mesh synthetic net). Sampling depths were 

 those determined for combined hydrobiologic research 

 (Timoshenkova & Kulikov, 1988)— that is, 5, 10. 25. 45. 70, 

 and 100 m. Inshallowregions, the lower level was detemiined 

 by the bottom depth at the station. Because of a special 



investigation of zooneuston carried out during the cruise, no 

 samples from zero level were collected. A BJN was used for 

 vertical tows to 100 m depth. 



Samples from the Niskin water sampler were filtered 

 through 100-mm mesh gauze. All samples of mesozooplankton 

 were fixed by formalin to the final concentration at 4% in the 

 sample. Identification of species found in the sample and their 

 total number calculation were carried out in a large Bogorov 

 chamber (10-ml) with stereoscopic binocular microscope 

 MSC-9 (LOMO). Samples collected with water bottles were 

 checked for individuals of size range 0. 1-2.0 mm, and samples 

 collected with nets, 2.0-20.0 mm. Fresh biomass was calculated 

 on the basis of average individual weights of organisms and 

 their total number (Lubny-Herzyg, 1953; Chislenko, 1968). 



Mesozooplankton sampling stations were classified using 

 the polytetic conjugating method of isolated adjunction of 

 hierarchic nonintersectional cluster analysis on the basis of 

 values of Checanovsky-Sjerensen generality indices (Pesenko, 

 1982) for quantitative data; 



/,, = min (P-. PJ; 



(1) 



where P,j, P,^ is the percent of i species in the total number of 

 mesozooplankton pernr inO-lOOm layer at j- and k-stations; 

 and for qualitative data: 



161 



