Metal Levels in Tissues of Florida Gar (Lepisosteus Platyrhincus) from Lake Okeechobee

There is considerable concern about the effects of contaminants on organisms at higher trophic levels, as well as interest in developing bioindicators of ecological health. In this article we examine the levels of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the gonads, liver and muscle of Florida gar (Lepisosteus platyrhincus) from Lake Okeechobee in south-central Florida. Gar are top-level predators in freshwater ecosystems. We expected that there would be differences in metal levels as a function of tissue, and predicted differences as a function of sex, size, and location around the lake. There were significant differences among tissues for all metals, but there were few differences as a function of size and gender, which may relate to the generally low levels of metals. Mercury levels were significantly higher in gar collected from the north, and arsenic levels were significantly higher in the gar collected from the south. All metal levels in the muscle of gar collected from Lake Okeechobee were similar to, or lower than those generally reported from other areas of the United States. Thus, although the levels of mercury from the Everglades to the south of Lake Okeechobee are sufficiently high to result in human fish consumption advisories, there are none for Lake Okeechobee. The mercury levels in fish muscle from Lake Okeechobee are lower than from many waters in the U.S. and do not pose a problem for humans. However, liver levels average over the 0.5 microg g(-1) level considered safe for human consumption, and might pose a problem for non-human consumers that eat the fish whole.