MARKO, P.B.; Univ. of North Carolina, Chapel Hill: Evidence of Self-recruitment of Populations in a Commercial Benthic Marine Species with Planktotrophic Larvae

The bay scallop (Argopecten irradians) was once an abundant member of sea grass communities along the US Atlantic coast and an important commercial and recreational shellfish species. Recent recruitment failures, however, have contributed to its widespread decline. One management option that may aid the recovery of depleted populations of marine species is to establish a network of marine reserves that is self-sustaining but that also resupplies harvested areas through the export of larvae. To design such a plan, an understanding of the spatial scale of larval dispersal is necessary. Despite having planktotrophic larvae, several lines of ecological and physical oceanographic evidence suggest that larval transport between adjacent sounds or basins in North Carolina may be infrequent for the bay scallop. Collection of genetic data from adult populations in 2002 supports this hypothesis, showing small but statistically significant structure between adjacent inshore basins on relatively small spatial scales (<20 km). Because estimates of population structure (i.e., FST) are notoriously difficult to interpret in terms of gene flow, I have also genetically analyzed recruits produced in the 2002-3 spawning season. Recruits collected within any one basin during 2002-3 tend to be most similar genetically to the resident adult populations in the same basin, a result consistent with retention of larvae within sounds on the NC coast.