Examining two epifaunal invertebrate communities using functional traits and environmental variables in and around Barrow canyon in the Chukchi and Beaufort seas

In the Arctic, benthic invertebrate communities are characterized by high species diversity and overall biomass when compared to corresponding benthic fish communities. Communities can be characterized with respect to their species diversity, biomass and the type of functions performed by the dominant organisms. Invertebrate communities with equally high species diversity may or may not have functionally similar traits. In this study, we examined basic functional traits of the dominant trawl-collected epifaunal invertebrates (e.g. mobility, feeding mode) along with environmental variables (e.g. sediment, salinity) in two high Arctic systems in and around Barrow Canyon; the northwest Chukchi Sea shelf (SHELFZ study, 2012) and the western Beaufort Sea shelf and upper slope (2008). The epifaunal communities are characterized by a large biomass of invertebrates (average of 5,000 kg/km2 in each) and species diversity ranged from 6-75 taxa per station in the Beaufort Sea (158 total) and 26-57 taxa per station in the Chukchi (215 total). These two communities share a commonality in taxonomic families, however, only 45 species occur in both. The top 2 dominant species within each community also differ; the filter-feeding basket star, Gorgonocephalus arcticus, and sea cucumber, Psolus peronii, dominate the offshore SHELFZ survey ( 60% of the biomass) while in the Beaufort Sea survey the primarily deposit feeding brittle star, Ophiura sarsi, and the mobile, predatory crab, Chionoecetes opilio, were the most biomass-prevalent species offshore (52% of the biomass). Oceanographic processes influencing water mass distribution in and around Barrow Canyon contribute to the benthic invertebrate community structure and the spatial variation in dominant functional traits. Finally, results from this study are discussed in the context of Arctic oil and gas development and climate change.