MEPS 354:141-146 (2008)  -  DOI: https://doi.org/10.3354/meps07257

ABSTRACT: Confined to a single enclave for more than a decade, the nassariid gastropod Cyclope neritea has expanded its range along the NW Iberian Peninsula (NWIP) region, forming dense populations in several locations. Unintended introductions from imported live shellfish seemed to be the probable vector for this recent proliferation. However, the relative proximity to the edges of the native range of this snail, together with some recent findings in areas similarly invaded by C. neritea (French Atlantic coast), raised the possibility that the species might be present in the NWIP for reasons other than human-mediated transfer. Moreover, it was unknown whether the recent proliferation was due to new independent re-introductions or to the spread from the earlier population. To provide some insight into these questions, we utilized the mitochondrial marker cytochrome oxidase I (533 bp) from individuals collected in 3 localities thought to cover the current known range of the species in the NWIP. Our results strongly confirm the non-native status of C. neritea, pointing to human-induced introductions as the probable cause for its presence in the NWIP. The Veneto region (Adriatic Sea) is the likely source for the introduced snails, while Manila clam transfers might be the major, even unique, vector of introduction, at least for the more recently settled localities. Recent independent re-introductions, rather than spread from an earlier introduction, appear to be the likely cause for the current proliferation of C. neritea within the region.

KEY WORDS: Biological introduction · Cyclope neritea · Cytochrome oxidase I · Genetic diversity · Mitochondrial DNA · Nassariidae · NW Iberian Peninsula