Trophic structure of the ichthyofauna in a Brazilian semiarid reservoir

The establishment of the trophic structure of fish provides information on species autoecology and their role in the ecosystem, in addition to supporting conservation and management practices for sustainable use of native species. In the semiarid region of Rio Grande do Norte there are few studies of the natural diet of fish. In this context, this study aimed to characterize the trophic structure of the fish assemblage of the Santa Cruz reservoir, Apodi, state of Rio Grande do Norte, Brazil. Fish were collected quarterly (February, May, August and November) in eight points in the reservoir in 2011. After screening, biometric identification and analysis, stomach or intestinal contents were analyzed and food items identified were used for the calculation of the frequency of occurrence and volumetric whose association gives the Alimentary Index (IAi). The highest consumption of a particular item grouped the species into five trophic guilds, and the detritivore/iliophagous, insectivore and carcinophagous the most abundant in the months and collection points, compared to herbivorous and piscivorous. The high abundance of individuals in these guilds can be explained by opportunistic species and the capture facility and intake of resources, since detritus/sediment, insects and shrimp are abundant in the environment studied. Thus, this study provided information about the items that contribute to the diet species, making it possible to infer about the interactions, allowing in the future to understand the complexity of trophic relationships and to assist the management practices and conservation of environment.