Effect of pollution on genetic diversity in the bay mussel Mytilus galloprovincialis and the acorn barnacle Balanus glandula

To test if environmental contamination acts as a selection force affecting genetic diversity at the population level, two intertidal invertebrate spec ies, Mytilus galloprovincialis and Balanus glandula, were collected from se ven different bay sites in southern California. Collections were made at th ree relatively pristine 'clean' sites and four 'impacted' sites exposed to heavy industrial or boating activity, and which had previously been identif ied as having measurable levels of pollution. Genetic diversity at each sit e was assessed by comparing fragment polymorphisms generated from genomic D NA by randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PC R). All populations retained a large amount of genetic diversity and were g enetically similar to each other. However, several different measures of di versity indicated that, for most primers, the populations of both species f rom impacted sites had lower genetic diversity compared to those population s from clean sites. Individuals at impacted sites were more likely to share the same haplotypes than were those from clean sites. Few bands seen in th e clean sites were absent from the impacted sites or vice versa, but a numb er of bands in the clean site populations were significantly less common in the impacted populations, while a few bands uncommon in clean site populat ions were more common at impacted sites. Together, these results suggest th at pollution at the impacted sites may reduce genetic diversity among the r esident invertebrate populations. (C) 2000 Elsevier Science Ltd. All rights reserved.