Zooplankton Abundance and Biomass Retrospective

Zooplankton abundance and biomass were measured during spring and late summer on the inner shelf of the southeastern Bering Sea in years of climate extremes. Samples were taken during late spring and late summer of three years: 1997, a year of moderate spring ice cover and unusually warm, calm summer conditions; 1998, a year of warm, but stormy summer conditions with very little spring ice cover; and 1999, a year of extensive spring ice cover, cold spring conditions and storms during spring and summer. Mean water column temperature was significantly lower during June 1999 than June 1998 and 1997. Copepod abundance and biomass during June were correlated with mean water column temperature and mean temperature below the thermocline. Mean calanoid abundance during June 1999 was 8 - 52 % of the mean abundance during 1998 and 1997. Significantly lower abundances during June 1999 were observed for Calanus marshallae, Acartia spp., Pseudocalanus spp. and calanoid nauplii. Significant interannual differences in mean water column temperature and calanoid abundance during late summer (late July-early September) were not detected. The Hirst-Lampitt equations were used to estimate the mean daily copepod production during the warm and cold years. This dataset is part of the Bering Sea Ecosystem Study-Bering Sea Integrated Ecosystem Research Program (BEST-BSIERP). BEST-BSIERP together are the Bering Sea project.