Doctor of Philosophy (Ph.D.)
Virginia Institute of Marine Science
L. C. Schaffner
The bioaccumulation and metabolism of organic contaminants (PAH, PCB) by three estuarine polychaetes, Nereis succinea (Frey and Leuckart 1847), Paraprionospio pinnata (Ehlers 1901) and Polydora ligni (Webster 1879), and by the fish predator, spot (Leiostomus xanthurus Lacepede 1802), were examined in laboratory experiments. Variations in trophic transfer of these contaminants resulting from differences in prey and contaminant type were also investigated. Toxicokinetic modeling reveals that metabolism of organic contaminants by invertebrate species result in variations in uptake, metabolism and elimination rate constants. Incorporation of prey metabolism potential in kinetic models increases the latter's predictability of biota-sediment accumulation factors (BSAFs), or the net result of uptake and elimination processes. With organisms that have moderate to high metabolic capabilities and slow metabolite elimination, high rates of metabolite formation will significantly underestimate the uptake clearance rate constant and BSAFs, and the models will have low predictive capabilities. Assimilation efficiency of organic contaminants by spot varies with prey type, metabolism and size; contaminant type; and is independent of prey concentration at low contaminant concentrations. Furthermore, toxicokinetic modeling indicate that there are significant differences in uptake and metabolism formation rate constants by spot due to variations in the metabolite content of its food, and significant differences in elimination rates between spot tissues and contaminant types. In addition, aqueous soluble metabolites from prey were less available to predators, and dietary accumulation factors are reduced with contaminant metabolism. The metabolic responses by organisms to toxic organic contaminants must be considered in toxicokinetic modeling, and knowledge of benthic invertebrate prey species metabolism can be used to increase the predictability of BSAF. The metabolism potential of both the prey and contaminant is therefore important in the long term, integrated process of trophic transfer. Differences in prey contaminant forms and concentrations will strongly influence the trophic transfer of organic contaminants. Predator diet will strongly influence its contaminant exposure and possible effects through preconsumptive metabolism of organic contaminants by prey. These results have important implications for modeling organic contaminant trophic transfer and fate in estuarine and coastal systems.
© The Author
Lay, Patrick Winfield, "Demersal predator exposure to toxic organic contaminants: Direct effects of macrofauna in trophic transfer" (1996). Dissertations, Theses, and Masters Projects. Paper 1539616733.