We investigated distinct feeding ecologies among benthic macroinvertebrates in the Bering Sea using relative proportions of fatty acids (FAs), FA biomarkers indicative of distinct sources of organic matter, and stable carbon isotope values of individual FAs. We extracted FAs from three bivalve species common to the region (Macoma calcarea, Nuculana radiata, and Ennucula tenuis), two polychaete species (Leitoscoloplos pugettensis and Nephtys sp.), and surface sediment scrapes collected during three periods corresponding to varying ice regimes in 2009 and 2010. The three bivalve species had indistinguishable diets, as inferred by overlapping FA profiles and d13C values for select FAs, and similar proportions of biomarker FAs indicative of FA source. FA isotope values from the bivalve taxa were most similar to values from benthic POM (b-POM). L. pugettensis, a deposit-feeding polychaete, had a distinct diet in which bacterial biomass made up a higher contribution to the total fatty acid pool relative to the bivalves and to Nephtys sp., a predatory polychaete. d13C FA values from the polychaetes were higher relative to those from the bivalves and to sediment scrapes. Distinct FA profiles between the two polychaetes indicate different sources of isotopic enrichment of FAs in these benthic invertebrates, which could include microbially-derived FAs or FAs derived from an ice algal source.