Ecologia trófica de grandes peixes pelágicos no Atlântico Sudoeste

Abstract

Understanding the trophic ecology of pelagic predators is essential to comprehending their ecological roles in ecosystems and developing effective management actions for the con-servation of these species. In this study, stable carbon and nitrogen isotope analyses were used to investigate resource partitioning among seven species of large pelagic fish: Thunnus atlan-ticus (blackfin tuna), Thunnus albacares (yellowfin tuna), Katsuwonus pelamis (skipjack tu-na), Sarda sarda (Atlantic bonito), Euthynnus alletteratus (little tunny), Coryphaena hippurus (mahi-mahi), Istiophorus albicans (sailfish), and Kajikia albida (white marlin). Samples were collected in the Cabo Frio region between 2009 and 2010. Isotopic ratios were estimated from muscle tissue samples, and statistical tests were used to compare the mean values of δ13C and δ15N among species and across individuals of different sizes. The Stable Isotope Bayesian Ellipses in R (SIBER) package was employed to calculate isotopic niches and the degree of overlap between species. The results revealed significant differences in the mean δ13C and δ15N values among species. T. albacares exhibited the highest mean δ13C values and the low-est δ15N values, whereas C. hippurus showed the lowest mean δ13C values, and S. sarda had the highest mean δ15N values. Regarding isotopic niche overlap, E. alletteratus displayed sub-stantial overlap with most species, including C. hippurus and K. pelamis (86.8% each). In contrast, S. sarda demonstrated the greatest niche segregation, showing minimal overlap with all other species. Finally, significant positive correlations between standard length and δ15N were identified for T. atlanticus, K. pelamis, E. alletteratus, and S. sarda. Additionally, signif-icant positive correlations between standard length and δ13C were reported for T. albacares and C. hippurus.