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THE EFFECT OF DIETARY ARSENIC ON SWIM-UP RAINBOW TROUT
Citation:
Hockett, J. R., R J. Erickson, T L. Highland, C. T. Jenson, E N. Leonard, V R. Mattson, AND D. R. Mount. THE EFFECT OF DIETARY ARSENIC ON SWIM-UP RAINBOW TROUT. Presented at SETAC Annual Meeting, Austin, TX, November 9-13, 2003.
Description:
Two 30-day toxicity tests were conducted in which swim-up rainbow trout were fed live diets of oligochaetes (Lumbriculus variegatus) containing elevated arsenic. Arsenic was incorporated into the diet by exposing oligochaetes to waterborne arsenate (test one) and waterborne arsenite (test two). For each test, L.variegatus were exposed to two elevated arsenic concentrations and a control. Rainbow trout were fed weighed rations of live oligochaetes daily; food rations were increased periodically to account for fish growth. Each dietary exposure treatment consisted of eight replicate chambers, each stocked initially with 8 rainbow trout fry (approximately 150 mg starting wwt). After 15 days of dietary exposure, half of the replicates of each treatment were destructively sampled. Fish weights and lengths were obtained, and randomly selected fish were analyzed for tissue arsenic. These same end-points were obtained from fish in the remaining four replicates after 30 days of dietary exposure. The results of both tests showed a clear adverse effect of dietary arsenic on rainbow trout growth. After 30 days of exposure, rainbow trout fed a diet contaminated with arsenate (high treatment = 106.5 g arsenic/g dwt) were 21.7% smaller than rainbow trout fed an uncontaminated diet; trout fed the live arsenite-contaminated diet (high treatment = 81.4 g arsenic/g dwt) were 19.8% smaller than rainbow trout fed the control diet. Based on the amount of food consumed, the observed decrease in growth was associated with a decrease in food conversion, rather than food avoidance. Fish exposed to dietary arsenic also showed changes in the consistency of their feces, suggesting incomplete digestion of the oligochaetes. Selected fish from the dietary arsenite exposure were processed for histological evaluation. This abstract does not necessarily reflect EPA policy.