Mercury Selection of Allozymes in Marine Organisms: Prediction and Verification in Nature

The geographic distributions of mercury-tolerant allozyme genotypes of the enzyme phosphoglucomutase in the shrimp Palaemon elegans and the enzyme phosphoglucose isomerase in the marine gastropod Monodonta turbinata were compared in a mercury-polluted site versus several unpolluted sites on the Israeli coast of the Mediterranean sea. We conclude that in both phosphoglucomutase and phosphoglucose isomerase, the level of the mercury-tolerant allozyme genotypes was higher in the polluted as compared with the unpolluted sites. These results suggest that mercury selection is operating in nature on allozyme genotypes of these marine organisms along patterns comparable with those found previously in laboratory experiments. We suggest that the enzymes studied here display an adaptive pattern in polluted environments. Therefore, they may be used as potential indicators and monitors of marine pollution.