Differences In Trace Metal Bioaccumulationkinetics Among Populations Of The Polychaete Nereisrndiversicolor From Metal-contaminated Estuaries

摘要

Aquatic organisms exposed to atypically high local bioavailabilities of a toxic metal may come under selection for changes in one or more physiological processes, including the rate of metal uptake from an available source of the metal, the rate of efflux and the rate of detoxification of accumulated metal into a relatively metabolically inert form. We investigated parameters of the bioaccumulation kinetics of the toxic metals Ag, Cd and Zn in populations of the estuarine polychaete worm Nereis diversicolor from differentially metal-contaminated sediments of 5 metal-rich estuaries in SW England and a relatively non-contaminated control estuary in SE England. One population (from Restronguet Creek, Cornwall) is known to be tolerant to raised availabilities of Zn and Cu. We compared uptake rate constants from solution (K_u) and assimilation efficiencies (AE) from sediment, and subsequent efflux rate constants (K_e) after uptake (from either water or ingested sediment) for each of the 3 metals among all populations. There was some limited interpopulation variation in the biodynamic parameters controlling bioaccumulation (and potential ecotoxicity) of trace metals between populations. There did not, however, appear to be consistent patterns to such variation. The basis of Zn tolerance in the Restronguet Creek population is not due to a reduction of Zn uptake from either solution or ingested sediment, or increased efflux of Zn accumulated after uptake from either route. The most likely mechanism is, therefore, an increased capacity for storage detoxification of Zn accumulated after regulation of Zn body concentration has broken down.