The Distribution of Zooplankton in the Bering Strait, July 1991.

Zooplankton was sampled at 16 stations across the Bering Strait during a joint Russian-U.S. research cruise at R/V Tiglax in July 1991. Vertical stratified tows (0 - bottom and 0 – thermocline depth) were done with a ring net (1 m diameter, 333 µm mesh). Distinct zooplankton communities were found in the Bering Sea/Anadyr and Alaskan water masses. The influence of the Anadyr water led to a decline in the number of species in the Bering Shelf water community in the western Bering Strait. Zooplankton biomass in the surface layer of Alaska coastal waters was 1.5 times higher than biomass in the surface layer of Bering/Anadyr waters. No differences were observed in zooplankton density and biomass between the thermocline and surface and bottom and surface in Alaska coastal waters, while in other regions maximum density and biomass occurred below the thermocline. Total zooplankton abundance and biomass in the Bering-Anadyr water were dominated by North Pacific species (e.g., Neocalanus plumchrus, Neocalanus cristatus, Metridia pacifica), while in the Alaskan water Calanus marshallae, Acartia spp., Centropages abdominalis and larval euphausiids were common. Physical concentration of zooplankton by currents led to highest zooplankton densities near the Diomede Islands.