MUDANÇAS COMPORTAMENTAIS EM Oreochromis niloticus COMO ENDPOINT DA TOXICIDADE DAS NANOPARTÍCULAS DE ZnO

Abstract

The toxicity of zinc oxide nanoparticles (ZnO NPs) has been demonstrated in different animal models. However, the concentrations tested in most studies are commonly much higher than those potentially identified in the environment. Therefore, this limits the applications of these studies in the evaluation of the ecotoxicological risk of these nanopoluents. In this sense, using the Oreochromis niloticus (Nile tilapia) as a model system, we aimed to evaluate the impacts of ZnO NPs (in environmentally relevant concentrations - 760 μg / L and 76000 μg / L, for 72 hours) on their responses behavioral. We did not evidence harmful effects of NPs on the locomotor abilities of the animals (evaluated in the open-field and light-dark transition test), nor predictive behavior of anxiety. On the other hand, the bioaccumulation of Zn in the body tissues of the tilapias was correlated with the alterations in the alimentary behavior (motivated by pellets of ration), as well as to the deficits of antipredatory defensive response (in individual and collective conditions). When confronted individually with their potential predators (Salminus brasiliensis), tilapia exposed to ZnO NPs presented lower rates of avoidance, flight and territorialist behavior. Already collectively, we observe the inability of animals to recognize their predators, as well as to differentiate them from artificial baits ("false predators"). To the best of our knowledge, the present study is the first to report biological impacts resulting from the short exposure of fish group representatives to ZnO NPs. Thus, we believe that it may be important for the knowledge about the ecotoxicological risks of these emerging pollutants.