Lipid-correction models for δ13C values across small pelagic fishes (Clupeiformes) from the Atlantic Ocean

Abstract

The interpretation of δ¹³C values in trophic ecology requires standardization of the lipid content of organisms estimated through their C:N ratio. To avoid time-consuming lipid extractions, the use of mathematical corrections has been developed for many years, and the conclusions generally point in the direction of species-specific adjustment of the models. This study aimed at defining the maximum taxonomic level required to obtain the best corrected δ¹³C values in small pelagic fish of the order Clupeiformes. δ¹³C values of six species were analyzed bulk and lipid-free, and were used to fit and validate linear and mass-balance models at different taxonomic levels. Despite a species effect combined with the C:N ratio effect, the corrected δ¹³C values produced by a global model for the Clupeiformes were as good as or better when compared to lipid-free samples than those produced by species-specific models, paving the way for possible generalization to other species in this order. At the order level, the linear model outperformed the mass-balance model.

Keywords: C:N ratio; Carbon isotope; Clupeiformes; Lipid removal; Trophic ecology.