Effects of Dietary Cd and Cu on Feeding and Growth Rates of the Landsnail Helix engaddensis

Effects of dietary cadmium and copper on feeding and growth rates of adult Helix engaddensis snails were studied for a 1-month period. The concentrations of cadmium were 0, 50, 100, 200, 400, and 800 μg Cd/g dry food, while those of copper were 0, 4, 20, 100, 500, and 2500 μg Cu/g dry food. Both metals inhibited feeding and growth rates significantly after 1 week and 3 weeks of exposure to Cd and Cu, respectively. Inhibition caused by Cd was found to be irreversible, which indicates toxicity, while that of Cu was reversible, indicating starvation because snails identified and refused to consume contaminated food. After 4 weeks of exposure, the NOEC of Cd was 50 μg/g and the LOEC was 100 μg/g, while those for Cu were 20 and 100 μg/g, respectively. EC50,75,90,100 (growth and feeding) values were calculated, and indicated that H. engaddensis snails are suitable for short-term toxicity bioassays.