Efeitos da temperatura e transparência da água sobre a proporção de peixes piscívoros em relação aos não piscívoros, em reservatórios neotropicais

Abstract

Trophic relationships are central themes in ecology, and the interaction between predators and prey is one of the main topics addressed on the balance of relationships. These questions are very discussed associated with impacted environments with differentiated characteristics such as hydroelectric plant reservoirs, whose damming affects the forms of trophic interactions of the remaining post-dam species. About the interactions of predation, it is known that some abiotic factors such as temperature and water transparency participate in the mediation of foraging, which may favor predatory success and increases in the proportion of predators in relation to prey. For this reason, considering that excessive increases of predators may threaten the trophic balance of communities, as well as environmental exclusions presented by impacted systems such as reservoirs, this study evaluated through logistic models, if during a period of 36 months thermal elevations and visibility Of the water corresponded to increases in the proportion of piscivorous fish in relation to non piscivorous fish, taking as reference 17 neotropical reservoirs. The results showed an increase of about 14% in the proportion of piscivorous when correlated to higher values of temperature and transparency acting together, indicating that small positive changes in these variables may be sufficient to increase the proportion of these predators. The discussions focused on the relationships between environmental variables and predatory events.