Behavioral analysis of fish in response to chondroitin and its applicability in the protection of ichthyofauna in the hydroelectric sector

Abstract

Alarm signals are released into the environment by the epidermal cells of aquatic communities to indicate danger situations. Chondroitin sulfate is indicated as one of the active compounds of alarm substances which can induce behavioral changes of avoidance in specimens that have chemical stimuli receptors. The potentiality of chondroitin for the development of a behavioral barrier to deter ichthyofauna was previously evaluated in laboratory tests (1, 2 and 5 µg L^-1) and subsequently in the draft tube (6 µg L^-1) of bulb-type turbines at a Hydroelectric Power Plant, on the Madeira River, in Rondônia, Brazil. In tests under controlled conditions with the Matrinxã and Tambaqui species, fast swimming and grouping were the most frequent alarm reactions in both species, with a greater number of episodes being observed at higher concentrations. In the draft tube, the injection of the concentrated chondroitin solution caused a decrease (55%) in the movement of confined fish, which indicates the deterrence of the ichthyofauna. The tests showed the potentiality of the sustainable use of chondroitin sulfate in the protection of ichthyofauna in hydroelectric projects.