Feeding and Growth Responses of the Snail <Emphasis Type="Italic">Theba pisana</Emphasis> to Dietary Metal Exposure

The effects of dietary exposure to copper (Cu), lead (Pb), and zinc (Zn) on feeding activities, growth response, and mortality of Theba pisana snails were studied in 5-week feeding tests. Snails were fed on an artificial diet containing the following Cu, Pb, or Zn concentrations: 0, 50, 100, 500, 1000, 5000, 10,000, and 15,000 μg/g dry food. At the end of 5 weeks, the food consumption rate was decreased with increasinges in both metal concentrations and time of exposure. The estimated concentrations of metals that reduces food consumption to 50% (EC₅₀) after 5 weeks were 56, 118, and 18 μg/g dry food for Cu, Pb, and Zn, respectively. All tested metals in the diet were found to inhibit growth of the snails in a dose-dependent manner. The toxic effect on growth of the tested metals could be arranged in the order Cu > Zn > Pb. The cumulative percentage mortality among snails fed a Cu- or Zn-contaminated diet was 73.3% and the respective value for a Pb-contaminated diet was 13.3%. There was a positive correlation between growth coefficient and food consumption for all tested metals.