Ecologia trófica e uso de habitat de odontocetos no nordeste do Brasil.

Abstract

Several ecological and morphologically diverse odontocetes live in the various marine environments associated with northeastern Brazil. To avoid competitive exclusion, sympatric species tend to diversify their niches and partition environmental and feeding resources. Nonetheless, the trophic ecology of odontocetes in northeastern Brazil is poorly understood. The present study used stable isotopes to investigate the trophic ecology and habitat use of odontocetes in the northwestern South Atlantic Ocean. Between 2006 and 2022, the stable carbon and nitrogen isotope ratios of 82 odontocetes found stranded on the Ceará and Rio Grande do Norte coastlines were determined. The highest mean δ13C were found in Sotalia guianensis (-15,5 ± 0,4‰) and Steno bredanensis (-15,5 ± 0,2 ‰), while the lowest mean value was in Stenella coeruleoalba (-18,0 ± 0,4 ‰) and G. griseus (-18,3 ‰). For δ15N, Stenella. longirostris had the lowest average (9,6 ± 0,9 ‰) and Stenella coeruleoalba (11,9 ± 2,1 ‰) had the highest mean value. The most overlapped isotopic niches were those of Steno bredanensis by Sotalia guianensis and of Tursiops truncatus by Stenella frontalis, in which 100% overlap was observed. The least overlapped elipse was that of Stenella coeruleoalba, only 2 % overlapped by Stenella clymene. Odontocetes use neritic and oceanic zones in the northwestern South Atlantic Ocean and oceanic waters are associated with higher diversity of trophic ecology among the community. The current study added to our knowledge of understudied species, like F. attenuata e Kogia spp., and reported various feeding strategies that allow several species to coexist in the region.