Ecologia trófica de Cichla temensis Humboldt 1821 do médio rio Negro, Amazonas, Brasil

Abstract

Understanding the trophic relationships between organisms and their environment is essential to interpreting the ecology of the species, and allows for the creation of policies aimed at sustainable management. One particular species of commercial importance in the Amazon basin is the speckled peacock bass (Cichla temensis). This species is the target of sport fishing and one of the main species of commercial and subsistence fishing in the Rio Negro basin. Nevertheless, no study on the trophic ecology of this species has been conducted in a natural environment in the Rio Negro basin. Thus, this study proposed to evaluate the trophic ecology of speckled peacock bass in two tributaries in the middle Rio Negro using analysis of stomach contents and stable isotopes of carbon and nitrogen. A review of the bibliographical resources underscored that using these tools together to study fish ecology can help elucidate issues related to the reproductive, migratory and feeding behavior of the fish. The stomach contents analysis confirmed the piscivorous feeding habit of the species and showed that the speckled peacock bass preyed on a variety species belonging to different trophic guilds. The length of the ingested prey increased with the size of the speckled peacock bass. Diet composition and trophic position were not different among size classes. δ13C values yielded significant shifts among the size classes: larger individuals displayed higher 13C values than smaller individuals. Trophic position varied between locations, with lowest values observed in fish from the Aracá River. This study demonstrated that diet of C. temensis may vary according to the size of the fish, and according to the river/locality, even within a same basin. We then suggest that further studies take into account local availability of food resources in order to better explore C. temensis diet and tropic ecology.