Experimental studies on some genetic effects of marine pollution

Abstract

Following the results of a series of investigations carried out to estimate the degree of marine pollution by utilizing certain marine filter feeders, such as the blue musselMytilus galloprovincialis, research has been planned to detect possible genetic effects of pollutants, with special attention to those acting at the population level. The possible selective role of pollutants has been studied both in natural (Mytilus) and in experimental (Tisbe holothuriae) populations by utilizing some electrophoretically-detected gene-enzyme systems as genetic markers. For some of the seven polymorphic loci studied inMytilus (AP, LAP, 6-PGD, IDH_s, IDH_m, PGI, PGM) significant changes in gene frequencies have been detected which can be related to the degree of pollution in the sampling areas. In the more polluted areas these changes were accompanied by a decrease in the frequency of heterozygotes. Similar changes in gene frequencies also occurred in laboratory populations of the copepodTisbe, reared under various experimental conditions. In particular, certain alleles of two loci, PGI-1 and AP-1, exhibited an increase in frequency, especially in populations cultured at various levels of oil pollution. This trend appeared more significant for the locus PGI. The fact that equilibria are reached and that the less favoured alleles are nevertheless maintained in the populations, even at extremely low frequencies, suggests the balanced nature of these enzyme polymorphisms. The significance of the above findings is briefly discussed.