Small-scale spatial variability in benthic food webs in the northeastern Chukchi Sea

Abstract

Benthic food-web structure can differ over large scales across Arctic shelves in relation to hydrographic conditions, but little is known if such differences also occur on smaller scales (10s of km) in hydrographically complex areas. The length, food sources, trophic composition, and energy distribution of benthic food webs in 3 neighboring study areas in the northeastern Chukchi Sea (i.e. Klondike, Burger, and Statoil, 3000 km2 each) were compared using stable isotope analysis and bomb calorimetry. Food-web length (4 trophic levels), food sources, and plots of δ13C versus δ15N were comparable among areas. Marked differences in food-web structure were observed when trophic levels in the 3 areas were quantified by benthic biomass and abundance. High proportions of biomass and abundance of trophic level (TL) 3 taxa at Burger were attributed to a large presence of refractory material. High proportions of TL 1 and TL 2 taxa at both Klondike and Statoil reflected higher availability of fresh material. Burger is a rich foraging ground for some benthic top predators due to high benthic prey energy densities. This study demonstrates that marine food webs can vary on small spatial scales with hydrographic conditions, particularly when quantitative trophic level distribution is considered.