Toxicity assessment of the Okefenokee Swamp
Dooley, Gregory Patrick
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The Okefenokee Swamp, GA once supported a substantial largemouth bass (Micropterus salmoides) fishery, however recent surveys suggest the population is declining. The objective of this study was to assess the toxicity of the Okefenokee Swamp to young largemouth bass. The assessment included laboratory exposures of juvenile largemouth bass to a range of pH and aluminum concentratio ns measured in the swamp and a modified USEPA Phase I Toxicity Identification Evaluation (TIE) with exposures of largemouth bass fry to swamp water. Largemouth bass exposed to pH 3.75 and 240 µg/L aluminum exhibited decreases in whole body sodium concentrations and altered gill morphology. The Phase I TIE indicated the low pH of the swamp was primarily responsible for the observed toxicity to largemouth bass. We concluded that the decline in largemouth bass in the Okefenokee Swamp is due primarily to the pH being reduced to lethal limits leading to failed recruitment of young fish.