Abundance and distribution of the alien Crepipatella dilatata in NW Atlantic Iberian Peninsula two decades after its first record

Abstract

Crepipatella dilatata was first reported out of its native range in south Galicia (NW Spain) in 2005. After that, there are no quantitative data about its abundance and the dynamics of its invasion. In this study, the abundance and distribution of C. dilatata were assessed in the area of the original invasion. The species was found in the intertidal of nearly all visited shores, preferring sheltered conditions and avoiding river mouths and wave exposed oceanic areas. Total abundance and biomass were significantly lower in southern internal area however, no significant differences were detected between areas (external, median and internal) and orientation (North and South) for the relative abundances of egg masses and sexual categories. Size-class frequencies also showed significant differences between areas and orientations suggesting a continuous recruitment. Therefore, overall results indicated that C. dilatata is well-established in the area.