Polychaetes that inhabit the sediments of estuaries are important prey to many species all around the world. Laeonereis acuta is a deposit feeder living in estuaries along the Atlantic coast of South America. Ragworms accumulate metals from the sediment, and represent a means of entry of sediment contaminants into the trophic network. The concentrations of Zn, Pb, Cu, Cr and Cd were determined in polychaetes and sediments (total and extractable) from six estuarine beaches of Río de la Plata. The associations between total and extractable concentrations in sediment and accumulated concentrations in L. acuta were analyzed. Sediments extracted by weak acid digestion appear to be a good proxy model of bioavailable metal fractions in the sediment. The association between metals in sediment and polychaetes denotes the role of L. acuta as an important link in metal trophic transfer from sediments to potential fish and bird predators of the worm.
Keywords: Bioavailability; Laeonereis acuta; Río de la Plata; Sediment; Trace metals.