SPRINGTIME MICROPROTOZOAN ABUNDANCE AND BIOMASS IN THE SOUTHEASTERN BERING-SEA AND SHELIKOF STRAIT, ALASKA

We surveyed springtime biomass and abundance of the >20 mu m microprot ozoa in surface waters of the SE Bering Sea and Shelikof Strait. Alask a. This study was part of the Fisheries Oceanography Coordinated Inves tigations (FOCI) program examining processes which affect the recruitm ent variability of walleye pollock (Theragra chalcogramma). Microproto zoa are a potential prey resource for larval pollock which has not bee n previously examined. In both areas, the >20 mu m microprotozoa were predominantly dinoflagellates and ciliates. At the time of sampling (M ay 1990 in Shelikof Strait and April 1992 in the SE Bering Sea), the s pring diatom bloom was under way in Shelikof Strait, but not in the SE Bering Sea. Heterotrophic dinoflagellates dominated the microprotozoa n assemblage in Shelikof Strait, but not in the SE Bering Sea. In the SE Bering Sea, total microprotozoan abundances ranged from 300 to 6233 organisms l(-1) and biomass from 0.58 to 9.73 mu g C l(-1). In Shelik of Strait, abundance and biomass were higher, ranging from 850 to 14 9 60 organisms l(-1) and from 1.29 to 70.73 mu g C l(-1), respectively. These biomass levels are comparable to those reported from other coast al and oceanic regions. Microprotozoan biomass levels were sufficient to support the estimated metabolic needs of first-feeding larval walle ye pollock. It remains to be shown whether larval pollock use this res ource.