Abstract

Scaridae (parrotfishes) represent a common family of herbivorous fishes on Caribbean reefs. They play a major role in controlling the algal dynamics of the reef benthic communities and are widely exploited by Caribbean fisheries. In this study, we stated the hypothesis that the coexistence of different species of Scaridae is allowed by the diversity of their trophic niches. To investigate this fact, a study was conducted on seven species of Scaridae (Sparisoma chrysopterum, S. rubripinne, S. aurofrenatum, S. viride, Scarus iseri, S. taeniopterus and S. vetula), abundant on the reefs of Guadeloupe. Gut content analyses were coupled with stable isotope analyses (13C/12C and 15N/14N ratios) to determine the trophic niche of the seven species. The contribution of sources to the fish diets was estimated using a mixing model. These fishes presented small ?15N differences, whereas they showed more scattered ?13C values, which imply the use of diversified sources of carbon. Among the seven studied species, three types of trophic niche were found. A first group of fishes, constituted by Sparisoma chrysopterum, S. rubripinne and Scarus iseri, mostly used macroalgae, especially algae at a juvenile stage present in the turf. Sparisoma viride, Scarus vetula and S. taeniopterus were grouped together due to their common use of living coral as protein intake along with macroalgae. Finally, Sparisoma aurofrenatum presented a specific diet, principally based on the assimilation of algal turf. The seven scarids species ingest and assimilate differently the food items, presenting thus different trophic niches. This diversity could allow them to share food resources without competitive interactions.

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