Structural features of zooplankton in the Bering Sea in spring-summer season
Size, species, and trophic structure of plankton in the eastern Bering Sea is considered on the data of surveys obtained in spring and summer of 1985. Intensive phytoplankton bloom with average biomass 1769 mg/m3 was observed in spring immediately after the sea ice melting. The bloom continued in summer in local areas located at the coast and above the continental slope but the biomass of phytoplankton was lower, on average 256 mg/m3. Zooplankton biomass was formed mainly by large-sized animals both in spring and summer. Its abundance was the highest in deep waters in spring and on the shelf in summer, when the share of Chaetognatha increased. However, Copepoda prevailed in zooplankton both in spring and summer; their abundance increased from shallows to the deep sea because the deep-water species are larger. The share of small-sized zooplankton increased in summer because of meroplankton and holoplankton larvae and juveniles mass appearance. Trophic structure of spring zooplankton communities in coastal and shelf areas of the Anadyr Bay and eastern Bering Sea was similar, with domination of predators in the coastal areas and domination of everyphages in the shelf areas, that is obviously reasoned by close neighborhood of these regions.