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VARIATION IN RESPONSIVENESS TO CONTAMINANTS IN WILD POPULATIONS OF ESTUARINE FISH, FUNDULUS HETERCLITUS
Citation:
Nacci, D E., L Coiro, D M. Champlin, AND S Jayaraman. VARIATION IN RESPONSIVENESS TO CONTAMINANTS IN WILD POPULATIONS OF ESTUARINE FISH, FUNDULUS HETERCLITUS. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting, Nashville, TN, November 12-16, 2000.
Description:
Populations of the non-migratory estuarine fish species Fundulus heteroclitus indigenous to a PCB-contaminated Superfund site (New Bedford Harbor, MA, USA) are markedly less sensitive to the toxic effects of local contaminants than those from a reference site. We characterized this resistance as an inherited adaptation that occurred in response to selective pressure by local contaminant exposures. We hypothesized that F. heteroclitus populations indigenous to sites producing exposures equivalent to those that were toxic in laboratory bioassays would be relatively insensitive (adapted) to the effects of the toxic dioxin-like congener 3,3',4,4',5-pentachloro biphenyl, CB126. Conversely, populations from those sites producing exposures equivalent to those that were non-toxic in laboratory bioassays would be as sensitive to CB126 as our reference population. To test this hypothesis, we sampled ten populations at increasing distance from the Superfund site (up to 60 km), and at distant clean and contaminated sites (>300 km). Sites were characterized by land use and surficial sediment PCB concentrations, ranging over five orders of magnitude. The results of laboratory bioassays using CBl26 demonstrated that contaminant responsiveness was inversely related to indigenous contaminant exposure. The threshold for the occurrence of adapted populations was similar to the PCB-sediment benchmark value for probable ecological effects, effects range median (ERM). Studies are currently underway to measure directly changes in the genetic structure of these fish populations, as well as potential costs of these genetic adaptations. These studies suggest approaches for predicting long-term effects of anthropogenic stressors, estimating the extent or frequency of such occurrences, and determining how biological, ecological and anthropogenic factors affect wild populations.