Diet of three juvenile fish species of the coastal zone of a Southwest Atlantic beach, Brazil

Surf zones are associated with a shelter area, nursery and feeding for several species of fish. In this study, the dietary habits of three species of fish with demersal habits (Gulf kingcroaker Menticirrhu gracilis, Whitesea catfish Genidens barbus and Barbu Polydacytlus virginicus), were verified in the surf zone area of an active urban beach of Baixada Santista, concerning structure in size, day and night abundances and overlapping diets. A total of 617 fish were analyzed, of which 362 were 194 were G. barbus and 61 were P. virginicus. Stomach contents, represented in Relative Importance Index diagrams, showed that the bivalve Donax gemmula is the most important food item for M. gracilis, scales of Teleostei for G. barbus and Euphausiacea for P. virginicus. In order to evaluate the similarity of the diets, the Macarthur & Levins indices and a cluster analysis with the Bray-Curtis distance were applied revealing that the diet is 44% different between G. barbus and M. gracilis, 5% between G. barbus and P. virginicus and of 84% between M. gracilis and P. virginicus. Anthropogenic waste like plastic, nylon, metal pieces, were only occasionaly observed.