Climate-driven changes in impacts of benthic predators in the northern Bering Sea

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Funds are provided to investigate a mechanism by which sea-ice change might affect the very productive, benthic-dominated food webs on shallow arctic shelves - expansion of the ranges and numbers of mobile benthic predators owing to increased temperature of bottom water. The main questions to be addressed are:Is the benthic food web in the north-central Bering Sea limited by top-down control by predators?Are the overwinter survival and/or prebreeding condition of Spectacled Eider (SPEI) being impacted by climate-driven trends in ice cover that are allowing populations of competing crabs and groundfish to expand?To answer these questions, the PIs will:Collect data needed to model the total impact of predators on their mainbenthic prey in the north-central Bering Sea. These predators include SPEI, groundfish, snow crabs, sea stars, and gastropods,Simulate impacts on the energy balance of the main endotherm predator (SPEI) of variations in crab and groundfish populations expected to occur with changes in ice cover and resulting temperature of bottom water, andContinue a long-term (1950-2004) record of benthic communities in this area that will contribute to the modeling and analyses listed above. Additionally, these data would also indicate whether declines in organic matter supply to sediments that have been measured at a subset of stations have occurred throughout the area, and whether these declines correspond to a decrease in direct precipitation of phytoplankton during and after the ice-edge spring bloom. A major unsolved challenge in modeling food webs of large marine ecosystems is integrating across levels of organization that operate at different temporal and spatial scales that might be critical to the carrying capacity of a large marine ecosystem for the entire predator community and determining how changes in that system affect the energy balance and distribution of top predators. In a novel approach to this problem, this study will integrate a spatially-explicit, individual-based model of the foraging energetics of SPEI with less detailed spatial models of benthic prey and less mobile predators.