Benthic community structure in the Chirikov Basin, northern Bering Sea: A comparison between 1986 and 2002

Macrobenthic infauna collections were made to investigate potential changes in community structure (abundance, biomass, diversity) in the Chirikov Basin, northern Bering Sea between 1986 and 2002; one of the biomass hot spot region in the Arctic. Two cruises to the Chirikov Basin were conducted in the years 1986 and 2002 with the R/V/ Alpha Helix. Samples were taken at the same 20 stations during both cruises, 15 of which were included in this study. Infauna was collected at each station with a 0.1m2 van Veen grab. Total abundance ranged from 343-13,373 individuals m-2 in 1986 and from 1093-11,418 individuals m-2 in 2002. Biomass ranged from 20-515g wet weight m-2 in 1986 and from 62-1694g wet weight m-2 in 2002. Total abundance and biomass in the Chirikov Basin were dominated by amphipods of the family Ampeliscidae. Other abundant taxa were other Crustacea, Mollusca and Polychaeta. Overall, a trend (though not statistically significant at all stations) for hi gher abundance and biomass was observed in 2002 compared to 1986. This thesis is part of a larger study in the Chirikov Basin that focused on ampeliscid amphipods only (Coyle et al, Deep-Sea Research II, scheduled for December 2007). This study used the WORMS and ITIS databases for the taxonomic information. Estimates of abundance are not corrected for detectability.