Caloric content of dominant benthic species from the northern Bering and Chukchi Seas: historical comparisons and the effects of preservation

Abstract

Energy density of a prey item provides information about the nutrition of a predator. Here, we provide data on energy content of 24 common benthic taxa (18 epifauna and six infauna) from the northern Bering and Chukchi Seas. Mollusks (both bivalves and gastropods) and amphipods had the highest caloric content of the taxa investigated. In light of changing environmental conditions and benthic communities in the Arctic, we compared present-day caloric content of several taxa with measurements conducted for the same taxa in the 1970s. In most cases, caloric content did not differ between historic and present-day values but was higher in two out of seven comparisons for both formalin-preserved samples and frozen materials. We also examined the effect of preservation methods (frozen vs. formalin-preserved) on the caloric content for seven epifaunal taxa. In three of the seven taxa, formalin-preserved specimens had significantly higher energy densities than frozen specimens. These data should make investigators aware of the opportunities and also possible limitations of including energy density values derived in different decades and from different preservation types into their calculations, although more comprehensive and time-controlled studies are needed to generate possible corrections factors.