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TA4 Metals in the Environment: Dietary Concerns in Aquatic Systems
(197) Effects of dietary copper, zinc, lead, cadmium, and arsenic on growth and survival of juvenile fish using live food organisms.
Erickson, R1, Highland, T1, Hockett, J1, Leonard, E1, Mattson, V1, Mount, D1, 1 U.S. Environmental Protection Agency, National Health and Environmental Effects Laboratory, Mid-Continent Ecology Division, Duluth, MN, USA
ABSTRACT- Except for certain organometallic compounds, dietary exposures of aquatic organisms to metal/metalloids have received little regulatory attention. However, various studies have suggested that dietary exposure could be important, especially in areas where current water column concentrations are low, but the food chain has high concentrations due to past contamination of sediments. For example, Woodward and coworkers found reduced growth in salmonids fed benthic invertebrates gathered from metal-contaminated sites in the Clark Fork River (CFR) basin. However, interpretation and application of such work is difficult due to the complex mixture of metals present and to nutritional differences among diets from different locations. And comparison of such work to most laboratory studies of dietary metal effects is made uncertain by the artificial nature of the contaminated diets in the laboratory studies. To better establish the dosimetry of dietary metals effects, we conducted a series of 30-day tests in which juveniles of three fish species (rainbow trout, fathead minnow, channel catfish) were fed a diet of live organisms (Lumbriculus variegatus) that had been exposed to water or sediment contaminated with different metal/metalloids. For copper, zinc, lead, and cadmium, no effects on survival or growth were observed at the maximum dietary concentrations tested, which were at least two-fold higher than those in CFR invertebrates reported to cause effects. However, for Lumbriculus exposed to arsenate or arsenite, significant reductions in rainbow trout growth were observed at tissue concentrations in the range of those reported for CFR invertebrates. Reduced growth occurred despite similar total daily food consumption rates among treatments. Arsenic contamination caused slower consumption of daily rations and apparent incomplete digestion of the food. Histological effects in the fish and arsenic speciation in the diet are being investigated. This abstract does not necessarily reflect EPA policy.
Key words: Fish, Dietary Exposure, Metals, Arsenic
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