Accumulation and elimination of trace metals in a transplantation experiment with Crassostrea rhizophorae

Oysters, Crassostrea rhizophorae, were reciprocally transplanted to two dif ferent sites: a contaminated site in the Cotegipe Channel at Aratu Bay and an uncontaminated site at Cacha-Prego, inside and outside of Todos os Santo s Bay (Brazil), respectively. Trace metal accumulation was measured after 0 , 15, 30, and 60 days of exposure at the contaminated site. Oysters transpl anted for 60 days from the clean to the contaminated site had accumulated c admium and lead to similar concentrations as found in the native oysters. T hey had also accumulated copper and zinc, but to lower levels compared to n ative specimens. Elimination experiments were carried out by transplanting oysters in the reverse direction. After 30 days, concentrations of cadmium and lead had decreased to levels comparable to those in the native specimen , whereas concentrations of copper and zinc did not diminish. A second elim ination experiment, bringing back to Cacha-Prego oysters that had been expo sed 60 days at Cotegipe Channel, indicated stronger decreases of copper and lead, but no clear changes of cadmium and zinc concentrations. The accumul ation experiment with C. rhizophorae is useful to estimate trace metal bioa vailability and changes in concentrations as a function of time at the cont aminated site. The different results of elimination experiments in the unco ntaminated site suggest different degrees of trace metal fixation after lon g-term and short-term accumulation periods.