Assemblage Structure and Spatial Distribution of Groundfish in the Northern Bering Sea in Relation to Environmental Variation

This study focuses on the impacts of benthic fish populations on the ecosystem in the northern Bering Sea. Climate change in both the Bering Sea and the regions of the Arctic have been dramatic, and one of the most obvious aspects has been the reduced extent and earlier melting of seasonal pack ice. The main question is weather and how the benthic fish community in the northern Bering Sea impact the ecosystem in response to changes in water temperatures and sea ice coverage. The immediate goal is to predict groundfish distribution under scenarios of increasing bottom water temperatures in the Bering Sea. Groundfish samples were collected in spring 2006 and 2007 in the northern Bering Sea around St. Lawrence Island (SLI). The structure of the entire community of benthic fish was examined and multivariate analyses (cluster analysis, multidimensional scaling) were used to predict ecologically based relationships between environmental factors and fish community structure in the northern Bering Sea. Arctic cod (Boreogadus saida), Bering flounder (Hippoglossoides robustus), and snailfish (Liparidae) were the dominant species south of SLI, whereas Arctic alligatorfish (Ulcina olrikii) and Arctic staghorn sculpin (Gymnocanthus tricuspis), or shorthorn sculpin (Myoxocephalus scorpius) were dominant north of SLI. The results indicate that bottom water (or water column) chlorophyll a and sediment parameters had greater influence on fish distribution in 2006 (cold, pre-bloom conditions), whereas bottom water temperature and sediment grain size were more important in 2007 (warm, bloom conditions) among a total of 14 environmental variables that were analyzed. These findings suggest strong linkages between physical conditions (e.g., water temperature and hydrography as it affects sediment grain size) and biological conditions (e.g., bloom status) in structuring fish communities in the northern Bering Sea.