Interannual variability of epibenthic communities in the Chukchi Sea, Alaska

Abstract

Epibenthic communities contain a wide range of organisms and serve an important role in marine ecosystems. They are involved in carbon remineralization, benthic production, and are important prey items for higher trophic levels. Arctic epibenthic communities may be experiencing significant changes in species composition, abundance, and biomass at both short and long term time scales. While epibenthic communities may be responding to long term shifts in the environment, differentiating long term trends from short term interannual variation can be problematic. The present study examined interannual differences of epibenthic communities and potential environmental drivers of their variability in the Chukchi Sea. For this, a plumb-staff beam trawl was used to sample epibenthic species composition, abundance, and biomass of the dominant invertebrate taxa at 71 stations around the Chukchi Sea during the ice free seasons of 2009, 2010, 2012, and 2013. Over the entire study area and within a smaller area with the most temporal coverage, the largest separation was between 2009 and 2013, with more difference between 2009 to 2010 than between 2012 and 2013. Crustaceans were the most significant contributors to community composition, based on abundance, and biomass. The important environmental drivers that varied along with the epibenthic community in some but not all years included bottom water temperature, salinity, dissolved oxygen, mean sediment chlorophyll a, and sediment organic matter. In contrast, sediment grain size was important in all years and, therefore, was the least likely to contribute to the biological variability among years. While these data provide a benchmark on interannual variability of epibenthic communities in the Chukchi Sea, more monitoring is essential to determine long term trends.