Physiological and toxicological effects of selenium and mercury mixtures in brook trout (Salvelinus fontinalis) and rainbow trout (Oncorhynchus mykiss)

Addition of Se to systems impacted by Hg has been considered for a remediation strategy because there is evidence that Se interacts with Hg in aquatic organisms, decreasing the accumulation and toxicity of Hg. However the current understanding of the potential adverse impacts of this strategy is limited. The present study investigated the species differences in the effects of Se/Hg mixtures in brook trout and rainbow trout. Fish maintained in the laboratory were fed Se-enriched diets, received a single injection of HgCl2 and were sampled on Day 28 of the exposure. Species differences in tissue levels of Se and Hg were detected, along with Se preventing the adverse effects of Hg on oxidative stress and thyroid function. Differences in Se and Hg compartmentalization and feeding behaviour in the laboratory may have caused the differences in the responses to the Se/Hg mixtures. Data on Se and Hg interactions and species differences are important for water quality management