A comparative study of ecological and genetical adaptation of three Iraqi fresh water snails in respect to heavy metal pollution

A. Sheriiff, H.; A. Delool, R.

	A comparative study of ecological and genetical adaptation of three Iraqi fresh water snails in respect to heavy metal pollution
Bulletin of the Iraq Natural History Museum
Article 1, Volume 9, Issue 3, 2002, Pages 69-76
Authors
H. A. Sheriiff; R. A. Delool
Abstract
A comparative study was carried out on ecological and genetical adaptation of three Iraqi freshwater snails, Physa acuta, Melanopsis buccinoidea and Melanoides tuberculata, in respect to acute toxicity of heavy metals (Zn, Cd and Hg). Longevity are used as poisoning tolerance criterion. LT 50 and LT 100 were determined for the studied snails at (0.5, 1, 5, and 10 ppm), for the three metals. Results indicated that Physa acuta had a higher tolerance than Melanopsis buccinoidea and Melanoides tuberculata, which was the lower one. Previous exposure to heavy metals in the original habitat was affecting on experimental tolerance and no relationships of physical and chemical factors (total hardness, temperature, D. O. and sulphate) between original and experimental exposuring has been occurred. Results indicated no ability of the three species for genetical adaptation on experimental bioassays, except for lower concentrations (0.5, 1 ppm), since Physa acuta managed to give more than two healthy new generations, whereas Melanopsis buccinoidea was disabled to give more than one weakling generation.The species Melanoides tuberculata showed a complete disability to give any generation . The present study suggested a new wide experiment to be design, not only by acute toxicity but with chronic toxicity, in order to determine the interference between the ecological and genetical adaptation and the previous exposure to many environmental pollutants.
Keywords
Physa acuta; Melanopsis buccinoidea; Melanoides tuberculata

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