Macrozoobenthos communities along the marine pipeline route at the Lunskoye field (shelf of northeastern Sakhalin) and their long-term variability

Results of benthos surveys conducted along the marine pipeline at the Lunskoe oilfield in July of 2006-2010 are presented. The sediment samples were taken at 59 stations with the depth 0-45 m by van Veen grab, 1-3 samples per each station, in total 375 samples. Macrozoobenthos was extracted from the sampled sediments by seawater washing through 1 mm sieve and preserved by 4 % buffered formaldehyde. Its species composition, biomass and abundance were determined according to standard techniques. Eight phyla and 257 species of macrozoobenthos are identified in the surveyed area, mainly amphipods (103 species) and polychaetes (60 species). Cumaceans and amphipod crustaceans dominate by their number and bivalve molluscs and cumaceans - by their biomass. Six benthic communities are revealed by the hierarchical agglomerative method of multidimensional clustering with group-average linking of Bray-Curtis similarities, after fourth root transformation of the species biomass values (PRIMER software). Type of the bottom sediments and depth are the main factors determining characteristics and distribution patterns of the benthic assemblages.