Dissolved heavy metals, lead, cadmium and mercury, accumulate in the body of the schistosome vector, Biomphalaria glabrata (Gastropoda: Pulmonata)

Abstract

The accumulation of lead, cadmium and mercury in the soft body mass of Biomphalaria glabrata (Say) exposed to dissolved chloride salts was determined. The effects of the heavy-metal exposure on the growth, mortality and reproduction were examined. The ranges of metal concentration tested were established following preliminary studies to determine their relative toxicity. Exposure to PbCl2 (1-250 μM), CdCl2 (0.05-0.5 μM,) or HgCl2 (0.1-2.5 μM) at 28°C for periods up to eight weeks resulted in small, but statistically significant mortality and decreased growth. No significant effects on reproduction were noted. At 17°C, mortality and growth were not affected by heavy-metal exposure over the eight-week observation period. Snails were not reproductively active at the lower temperature. Spectrophotometric analyses demonstrated that snails exposed to Pb, Cd or Hg had significantly elevated levels of these metals in their bodies within four weeks at 17° or 28°C, indicating that this species and/or its close relatives may prove valuable as biomonitors for heavy-metal pollution.