Snail abundance in freshwater canals in the eastern province of Saudi Arabia and acute toxicity studies of copper sulphate in Biomphalaria arabica and Lymnaea auricularia

Abstract

The present study aimed to investigate the distribution of three species of freshwater snails, namely; Biomphalaria Arabica; Planorbidae, Lymnaea auricularia; Lymnaeidae and Melanoides tuberculatus; Thiaridae in two different parallel canals (the concrete irrigation and the earthen drainage canals) in the eastern province of Saudi Arabia and the effect of copper sulphate pentahydrate (CuSO₄.5H₂O) on mortality of the first two species after 24 h of exposure. The physico-chemical properties of the water especially, temperature and pH were determined as important factors for snail distribution. The results show that the water temperature and the pH of the two canals were almost the same. The range of water temperature was 25.8 to 28.3°C, while the water pH was 6.6 to 6.8. The two canals were occupied by three species of aquatic snails viz. B. arabica, L. auricularia and M. tuberculatus. The bioassay of CuSO₄.5H₂O on only two snail species showed 24 h–LC₅₀ as 5.7 ppm for B. arabicus and 7.8 ppm for L. auricularia. This result reveals that CuSO₄.5H₂O was highly effective in snail eradication. On the basis of the present study, it is recommended that some further studies on the canals including all environmental factors should be investigated for their role in aquatic snail distribution. However, the chronic effect of lower lethal dose of CuSO₄.5H₂O on the snails mortality and their effects on developmental stages should be investigated, and some local plant extract should also be tried for their potency on snail mortality.

Key words: Biomphalaria, Lymnea, Melanoides, distribution, freshwater snails, copper sulphate, Saudi Arabia.