Effect of selenium exposure on the freshwater bivalve Corbicula fluminea

Abstract

Abstract. Selenium is essential for most of living organisms. In normoxic to moderately hypoxic freshwaters, Se exists predominantly in the (+VI) and (+IV) oxidation states as selenate and selenite respectively, whereas in the biota it is incorporated as Se (-II) or Se (0). At low concentrations, it acts against oxidative damages, but it may be toxic at higher levels. In filter feeders, such as the freshwater bivalve Corbicula fluminea, the ventilatory activity is a primary limiting step that controls the water influx and therefore the delivery of contaminants. A number of different parameters such as algal food density or presence of contaminant can influence the ventilation and hence the bioaccumulation potential of the contaminant. We report here a set of short-term experiments performed to study the effects of different forms of dissolved Se (selenite, selenate, selenomethionine) and algal-bound Se on the ventilatory activity of Corbicula fluminea and to evaluate the Se bioaccumulation. All experiments were performed on a 3-day exposure period after acclimatizing the organisms during a 7-day period to the synthetic water, at a regulated algal density. Both bioaccumulation and ventilatory activity of Se exposed groups, in comparison to these of the reference group, varied greatly according to the form of Se used.