Can dams affect the trophic structure of ichthyofauna? A long-term effects in the Neotropical region

Podem barragens afetar a estrutura trófica da ictiofauna? Efeitos de longo prazo na Região Neotropical

ABSTRACT

Dams are considered an important source of modification upon the structure of aquatic communities and their reflexes are diverse on the fish fauna. Although there are several hydroelectric power plants in Brazil, the long-term effects on feeding activity of ichthyofauna are unknown. Thus, this study aimed to investigate the long-term effects of an old reservoir (fifty years) on the trophic dynamics of fish fauna. The diet of 20 fish species was analyzed, identifying 37 food items belonging to six trophic categories, which enable to create six trophic groups. The results found here suggests that throughout the creation of a reservoir, the trophic structure of the fish assemblages tend to reach trophic homeostasis, in which the fish community will be capable of exploring the most available food resources being maintained primarily by the items placed in the categories organic matter and fragments of fish and vegetal.

KEYWORDS
Feeding ecology; old dam; trophic stabilization; resource availability; fishes