MEPS 557:161-175 (2016)  -  DOI:

Feeding ecologies of key bivalve and polychaete species in the Bering Sea as elucidated by fatty acid and compound-specific stable isotope analyses

L. E. Oxtoby1,2,*, S. M. Budge3, K. Iken1, D. M. O’Brien4, M. J. Wooller1,2

1Institute of Marine Science, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 905 N. Koyukuk Drive, Fairbanks, AK 99775, USA
2Alaska Stable Isotope Facility, Water and Environmental Research Center, University of Alaska Fairbanks, 306 Tanana Loop, Fairbanks, AK 99775, USA
3Department of Process Engineering and Applied Science, Dalhousie University, PO Box 1000, Halifax, NS B3J 2X4, Canada
4Institute of Arctic Biology, University of Alaska Fairbanks, 230 Arctic Health Research Building, Fairbanks, AK 99775, USA
*Corresponding author:

ABSTRACT: We characterized the feeding ecologies of common bivalves Macoma calcarea, Nuculana radiata, and Ennucula tenuis, and polychaetes Leitoscoloplos pugettensis and Nephtys spp. from the Bering Sea using relative proportions of fatty acids (FA profiles), FAs indicative of distinct organic matter sources (FA markers), and stable carbon isotope values of FA markers. We measured FAs from these invertebrates and from surface sediment scrapes collected during March to July in 2009 and 2010. The bivalve species had indistinguishable trophic signatures, as inferred by overlapping FA profiles and δ13C values for algal marker FAs, and similar proportions of FA markers. FA δ13C values from bivalve taxa were most similar to FA δ13C values from particulate organic matter (POM) from surface sediments. In contrast, δ13C values for the algal marker eicosapentaenoic acid in the polychaetes were higher relative to those from the bivalves and sediment from the same locations (mean difference of 3.6‰), suggesting low direct dietary contributions of benthic POM from surface sediments. L. pugettensis, a head-down deposit-feeding polychaete, had a higher contribution from bacterial sources to its total FA pool relative to the bivalves and to Nephtys spp., a predatory polychaete, based on a bacterial FA marker. Distinct FA profiles between the polychaetes imply different proportional contributions of dietary FA sources, including greater contribution of microbially altered FAs to L. pugettensis and greater contribution of ice algal FAs to Nephtys spp. Our findings revealed resource partitioning among select benthic invertebrates and suggest that responses to climate-induced changes in sub-Arctic production may be species specific.

KEY WORDS: Arctic benthos · Trophic markers · Bacteria · Sea ice algae · Phytoplankton · Microphytobenthos

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Cite this article as: Oxtoby LE, Budge SM, Iken K, O’Brien DM, Wooller MJ (2016) Feeding ecologies of key bivalve and polychaete species in the Bering Sea as elucidated by fatty acid and compound-specific stable isotope analyses. Mar Ecol Prog Ser 557:161-175.

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