Assessment of heavy metal (Ni, Cu) interactions in binary mixture to rainbow trout (Oncorhynchus mykiss) at early life stages

Abstract

Lethal toxicity test and sublethal short-term and long-term toxicity tests on embryos and larvae of rainbow trout Oncorhynchus mykiss (beginning from “eye-egg” embryos and from 1-day old larvae) were performed. Lethal and sublethal toxic effects of the 1.0, 0.5, 0.25, 0.125 and 0.06 portion of the LC50 of Cu, Ni singly and their binary mixtures (Cu+Ni) were analyzed. The mixtures according to 96-hour LC50 for embryos and 96-hour LC50 for larvae were prepared. During exposure such biological parameters of the embryos and larvae as: mortality; gill ventilation frequency, behavioral responses of larvae were evaluated. Lethal toxicity test showed that the 96- hour LC50 values for embryos and larvae were different, and depended on the mixture preparation mode, heavy metal concentration in the mixture, and development stage of organism. Sublethal exposure of mixture disordered gill ventilation function in larvae, affected behavioral reactions, and depended on the mixture of preparation mode, heavy metal concentration in the mixture, duration of exposure and affected development stage of organism. Obtained data showed that toxicity assessment in fish at early stages of their development is important for evaluation of water pollution with heavy metals and prediction of their risk to aquatic animal populations.