Abstract

Stable isotope analyses, especially carbon (12C:13C) and nitrogen (14N:15N) ratios, are widely used in ecology to study habitat use, trophic niches, structure of food-webs, or migrations. Muscles are commonly used for these analyses because this tissue is homogeneous and presents a moderate turn-over time (around three months for fish), that allow the study of ecological parameters in a relatively short period. However, the use of muscle generally requires the sacrifice of individuals. In the present study, the use of fins to perform stable isotope analyses was tested. Two herbivorous fish species were studied (Sparisoma viride and Acanthurus bahianus) on a reef site located the West coast of Guadeloupe. These two species were chosen due to their major ecological role on coral reef, in regulating algal biomass, and due to the scientific interest they represent in ecology. For each individual, three samples were collected: white dorsal muscle, pieces of pectoral and dorsal fins. Measurements of carbon and nitrogen signatures were conducted on each sample. Statistical correlations were done between isotopic signatures of muscle and those of fins. Results showed significant positive correlations between muscle and fins isotopic ratios, for both carbon and nitrogen isotopic ratios. The respective equations of correlation were calculated, as well as the Spearman’s coefficient of correlation. For both fish species, coefficients of correlation were higher when comparing isotopic signature of muscle and those of pectoral fins. Correlations with dorsal fins appeared to be less efficient. These results suggest that fins, especially pectoral fins, could be used for stable isotope analyses instead of muscle. This practice could allow collaboration between scientists and fishers, as the removal of a piece of fin is not visible on

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