Feeding, trophic level, southwestern atlantic, Bluefish, Skipjack tuna, stingrays
Feeding, trophic level, southwestern atlantic, Bluefish, Skipjack tuna, stingrays
The composition of the stomach contents of 989 individuals of the species Katsuwonus pelamis (93), Pomatomus saltatrix (521), Atlantoraja cyclophora (129) and Rioraja agassizii (246) captured off the coast of Rio de Janeiro was analyzed. Of the pelagic species, Katsuwonus pelamis, showed to have a specialist feeding strategy, consuming predominantly sardines (Sardinella brasiliensis), while Pomatomus saltatrix has its diet composed mainly of eagle owls (Dactylopterus volitans) and a specialist-opportunistic strategy. Among the demersal stingray species, Atlantoraja cyclophora and Rioraja agassizii, similar feeding strategies were observed, with preference for the consumption of crustaceans, mainly Pleoticus muelleri and Peneidae, respectively. No significant differences were found between the diets of pelagic species, both piscivorous, occupying high trophic levels, typical of top predators of the food chain (4.4 and 4.8). The food niche overlap between them is intermediate (Ba = 0.54). The results suggest that there is some partition of food resources available in the environment. The diet of P. saltatrix is more diversified. The consumption of coió in summer and autumn deserves to be highlighted. Among the demersal species, no marked differences were observed either. Both species of stingrays consume mainly crustaceans and fish, occupying trophic levels between 3.8 and 3.9 and have low food niche overlap (Ba = 0.30). The generated results confirm that all species occupy high trophic levels and consume mainly fish and crustaceans. Seasonal variations in the diets of these species may be related to their availability. The low values of food niche overlap between species, linked to the diversity of food items available in the home range of the species, also suggest a condition of little interspecific competition.