Density and distribution of meiofauna in the northeastern Chukchi Sea

Abstract

Meiofaunal communities in the northeastern Chukchi Sea (Alaska) are poorly known and were investigated to determine coarse taxonomic composition, distributional patterns, and density and biomass. Core samples were taken in August through October 2012 from van Veen grabs at depths of 20-45 m, in order to assess meiofauna community structure and associations with environmental and biological variables. Overall, density and biomass were dominated by nematodes, harpacticoid copepods, and foraminifera. Total meiofaunal density (9-13 ind. cm-2) was lower than in some deeper polar regions (e.g., Yermak Plateau and Nansen Basin), but generally fell within the range of published estimates for the Arctic and sub-Arctic. Total region-averaged biomass (27.4 mg C m-2) was similar to estimates for the deep Arctic Makarov and Amundsen Basins, but was much lower than shallow and productive sub-Arctic regions such as the Oosterschelde estuary (North Sea, Netherlands) and intertidal areas in Kongsfjorden (Svalbard), and some Arctic locations in the Barents Sea. The ratio of meiofaunal to macrofaunal biomass (1:438) was comparable to estimates from less productive Arctic basins and from fjords, but was unexpectedly lower than other productive polar shelves (e.g., Barents Sea shelf). Regression analysis and Canonical Correspondence Analysis (CCA) ordination suggest water depth, % mud, and TOC are important predictors of nematode and harpacticoid copepod densities, whereas temperature, TOC, and macrofaunal biomass were correlated with meiofaunal community structure. These variables are proxies for the topographic control and water circulation in the region, and suggest circulation with advected nutrient input as the primary driving force behind community density and distribution patterns.