Abstract
Beach erosion - as a consequence of coastal development and sea level rise - can result in habitat fragmentation and habitat loss. Apart from the immediate implications of habitat loss for local beach communities, increased habitat fragmentation may have far-reaching consequences for meta-populations across large geographic scales by interrupting dispersal (and colonisation) patterns among beaches. This may ultimately lead to the extinction of a species. A better understanding of the connectivity among sandy beach species is necessary in order to gauge the resilience of populations and to predict the impact of habitat fragmentation on beach communities. Therefore, this study aims to assess the genetic connectivity of populations of a beach clam, Donax serra, across two biogeographic zones along the West and South coasts of South Africa. D. serra has a pelagic larval phase during its development which is expected to facilitate dispersal and hence connectivity among populations. Preliminary results from a limited number of cytochrome c oxidase subunit 1 (CO1) sequences failed to reveal genetic differentiation among populations within and between of biogeographic regions in both species. These results may indeed indicate connectivity, either by recent separation or frequent dispersal. Analysis of additional samples and DNA regions (loci) may be required to unravel these two explanations, which may have considerable implications for the conservation status of sandy beaches.