HP10 New Advances in Estimating Effects of Toxicants on Populations
D135-136
1:20 PM - 5:20 PM, Thursday
() Impact of the accumulation of narcotics on structure and function of a population of Fundulus heteroclitus.
Merten, A.1, 2, Beard, E.1, Baker, J.1, 1 University of Maryland Chesapeake Biological Laboratory, Solomons, Maryland, USA2 NOAA, Office of Response and Restoration, Hazardous Materials and Response, Seattle, Washington, USA
ABSTRACT- Accumulation of non-polar narcotic chemicals in organisms alters their metabolic rates and, therefore their energetic demands. Since exposure of hydrophobic organic chemicals (HOCs) is primarily through the diet, we hypothesize that decreasing metabolic rates caused by accumulation of narcotics reduces feeding, further decreasing exposure to the narcotic. Thus, dietary exposure to and accumulation of narcotics may cause a negative feedback, reducing net bioaccumulation. A 120-day exposure experiment examined the consequences on the bioenergetics and bioaccumulation rates of the estuarine fish Fundulus heteroclitus continuously challenged with sublethal levels of HOCs. Clams contaminated with polycyclic aromatic hydrocarbons (
PAHs of 42 analytes, 3000 - 5000 ng/g wet) were the contaminant stressor in a gradient of contaminated food, and PCB congeners at much lower levels (75 ng/g-wet PCBs) were used to trace uptake dynamics. One half of the experiment was run with clean water, while the other half included low level aqueous exposure to MS222 (a model narcotic chemical). We found no statistically significant differences in weight, length, or condition factors among treatments, indicating the subtle nature of the narcotic stress. Standard metabolic rates and PCB accumulation were statistically different between the control group and the group fed the highest levels of PAH-contaminated clams. The control group did not accumulate PCBs with time but the group fed the most contaminated food accumulated PCBs during the course of the experiment, and did not reach steady state. Results are interpreted using a fish bioenergetics model modified to include a narcosis induction model, which was run under three sets of conditions: base case energetics with no HOC exposure, base case energetics with bioaccumulation, and cases with altered energetics due to HOC accumulation. Comparative model runs were evaluated to quantify contaminant effects. We evaluated long-term, population-level consequences of sublethal exposures to narcotic contaminants.
Key words: PAH, narcosis, Fundulus heteroclitus, bioenergetics