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Marine Ecology Progress Series

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MEPS 531:15-32 (2015)  -  DOI:

Regional benthic food web structure on the Alaska Beaufort Sea shelf

Lauren M. Divine1,*, Katrin Iken1, Bodil A. Bluhm1,2

1School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, PO Box 757220, Fairbanks, Alaska 99775-7220, USA
2Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, 9037 Tromsø, Norway
*Corresponding author:

ABSTRACT: Trophic structure and resilience of regional benthic food webs were studied on the Alaska Beaufort Sea shelf across 3 geographic regions (east, central, and west) and 2 depth ranges (14 to 90 m [shallow] and 100 to 220 m [deep]). Carbon (δ13C) and nitrogen (δ15N) isotope ratios were measured from water column and sediment particulate organic matter (POM) as markers of primary food sources and from common benthic invertebrate taxa. Isotopic niche space (δ13C-δ15N) occupied by benthic taxa provided measures of community-wide trophic redundancy and separation. δ13C values of the water column and sediment POM were patchy but generally indicative of terrestrial input across the shelf, especially near the mouth of the Colville River (< -25.5‰). Food web structures in the shallow and deep western Beaufort regions, however, reflected marine carbon inputs, with most consumers occupying intermediate trophic levels (TLs) and food webs of intermediate trophic redundancy and separation relative to the other regions. In the central shallow and east regions, the terrestrial carbon found in sediments was mirrored in consumer tissues. The central deep region contained the highest proportions of higher TL taxa, particularly within the predator feeding guild, possibly reflecting resource partitioning of a limited prey spectrum. The comparatively large isotopic niche space in the central deep region, with high trophic niche separation but low trophic redundancy, suggests that this region may be most vulnerable to perturbations. This study provides a valuable new understanding of benthic food web dynamics in the understudied Alaska Beaufort Sea region and represents a baseline for future comparison.

KEY WORDS: Benthos · Carbon · Feeding guild · Nitrogen · Stable isotope · Trophic structure

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Cite this article as: Divine LM, Iken K, Bluhm BA (2015) Regional benthic food web structure on the Alaska Beaufort Sea shelf. Mar Ecol Prog Ser 531:15-32.

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