The Fresh Water Growing Snail Physa acuta : A Suitable Bioindicator
for Testing Cadmium Toxicity

Mohammad A.M. Wadaan
Department of Zoology, College of Science, King Saud University, P. O. Box 2455,
Riyadh - 11451, Saudi Arabia.

                                                                                   Abstract

The present study was aimed to test the toxicity of cadmium (Cd) on the viability and growth of the newly hatched juvenile snails Physa acuta. Also it was intended to investigate whether such parameter could be used as a suitable bioindicator for testing metal toxicity. Juvenile snails were used as a source of experimental material from the collected and cultured P. acuta snails under laboratory conditions. Cd solution was prepared in two series of dilutions, viz., Series I - concentrations ranged from 0.03125 to 0.5 ppm, and Series I I- concentrations ranged from 0.5 to 2.5 ppm. Approximately 15 - 20 juvenile snails were kept in each petridish with 60 ml of distilled water containing the Cd doses. Growth, viability and mortality of these juvenile snails were observed weekly for 12 weeks post-treatment. Overall, the lower concentrations of Cd in Series I was more toxic than that of the higher ranges in Series II. In both series of dilutions, the Cd effect on mortality rate of the snails was biphasic. Based on these findings, the present study suggests that the fresh water snail, P. acuta can be used as a bioindicator for testing metal toxicity under laboratory conditions.

Key words: Physa acuta, juvenile snails, Cadmium, bioindicator, toxicity.

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