Whitefish (Coregonus lavaretus) respiration rate governs intra-otolith variation of δ13C values in Lake Annecy

Abstract

We generated 10 high-resolution profiles of stable carbon and oxygen isotope values (δ13Coto and δ18Ooto) of sagittal otoliths of whitefish (Coregonus lavaretus) from Lake Annecy (France) to determine the factors that control intra-individual δ13Coto variation. Dominant patterns of intra-otolith variation compared well with seasonal and age-specific respiration modeling. Conversely, intra-otolith variation of δ13C values did not compare well with measured dietary and environmental variation. We infer that the proportion of metabolically sourced carbon (M) is the dominant control on intra-otolith variation. Current models of otolith carbon incorporation provide different estimates of M. Once appropriate fractionation factors among otolith, endolymph, blood, and carbon sources are elucidated, δ13Coto values will reveal energetic, environmental, and dietary information of teleost fish for past and present populations. Used in conjunction with δ18Ooto values, δ13Coto values will be powerful proxies of fish environment, behavior, and evolution.