Published online by Cambridge University Press: 19 December 2012
Populations of the marine molluscan bivalve Dosinia exoleta in Galicia(northwest Spain) present lead (Pb) concentrations above the limit for human consumption.Accordingly, its collection for human consumption was forbidden since 2008. The highbioaccumulation of Pb in this species is surprising given that Pb concentrations are notvery high in its environment and that other bivalve infaunal species inhabiting the sameareas do not show such high Pb contents. This study reports the discovery and descriptionof extracellular granules present in the kidney tubule lumina of this species. Largegranules (20−200 μm) mainly composed of calcium phosphate representbetween 50% and 75% of the dry weight of the kidneys. Metal analysis revealed that from 78to 98% of the Pb body burden was present in the kidney, and from 87% to 92% of this Pbwithin the kidney was contained in metal rich granules. Most of the zinc in these bivalveswas also found to be associated with these kidney granules, while other metals, such ascopper and cadmium, were associated with other kidney fractions. This study confirms thatthe high Pb concentrations observed in D. exoleta, and the relationshipof Pb concentration with individual size, are due to the inclusion of Pb in kidneygranules that accumulate in the kidney lumen over the course of the bivalve’s life.