Mercury and selenium in fish from the Savannah River: Species, trophic level, and locational differences

Levels of contaminants in fish are of considerable interest because of pote ntial effects on the fish themselves, as well as on other organisms that co nsume them. In this article we compare the mercury levels in muscle tissue of 11 fish species from the Savannah River, as well as selenium levels beca use of its known protective effect against mercury toxicity. We sampled fis h from three stretches of the river: upstream, along, and downstream the De partment of Energy's Savannah River Site, a former nuclear material product ion facility. We test the null hypothesis that there were no differences in mercury and selenium levels in fish tissue as a function of species, troph ic level, and location along the river. There were significant interspecifi c differences in mercury levels, with bowfin (Amia calva) having the highes t levels, followed by largemouth bass (Micropterus salmoides) and pickerel (Esox niger). Sunfish (Lepomis spp.) had the lowest levels of mercury. As e xpected, these differences generally reflected trophic levels. There were f ew significant locational differences in mercury levels, and existing diffe rences were not great, presumably reflecting local movements of fish betwee n the sites examined. Selenium and mercury concentrations were positively c orrelated only for bass, perch (Perca flavescens), and red-breasted sunfish (Lepomis auritus). Mercury levels were positively correlated with body mas s of the fish for all species except American eel (Anguilla rostrata) and b luegill sunfish (L. macrochirus). The mercury and selenium levels in fish t issue from the Savannah River are similar to or lower than those reported i n many other studies, and in most cases pose little risk to the fish themse lves or to other aquatic consumers, although levels in bowfin and bass are sufficiently high to pose a potential threat to high-level consumers. (C) 2 001 Academic Press.