Estudo comparativo da toxicidade e dos mecanismos de ação tóxica de nanopartículas de cobre e cobre em duas espécies de peixes da Amazônia: Apistogramma agassizii e Paracheirodon axlerodi

Abstract

Copper oxide nanoparticles (nCuO) are widely used in boat antifouling paints, and are released into the environment, inducing toxicity to aquatic organisms. The present study aimed to understand the effects of nCuO and dissolved copper on two ornamental Amazon fish species: Apistogramma agassizii and Paracheirodon axelrodi. Fish were exposed to 50% nCuO LC50 (A. agassizii 375 μg L-1 and P. axelrodi 460 μg L-1) and 50% Cu LC50 (A. agassizii 20 mg L-1 and P. axelrodi 22.9 μg L-1) for 24, 48, 72 and 96 hours. Metabolic rate (MO2), gill osmorregulatory processes, gill mitochondria oxidative phosphorylation capacity and ROS generation, oxidative stress defense and morfological damages were evaluated. Our results showed a strong increase in MO2 and a higher impairment in its gill’s morphology in P. axelrodi after the copper exposures. Differently, A. agassizii presented an increased proton leak (i.e. uncoupling between respiration and ATP production) in response to nCuO and Cu exposure, thus decreasing their Respiratory Control Rate (RCR). Interestingly, this uncoupling was directly related to an increase in ROS levels. Our findings reveal that the metabolic responses of these two species in response to nCuO and Cu, which are probably caused by the differences between species natural histories, indicating that different mechanisms of toxic action of the contaminants are associated to differences in the sensibility of these two species.