Temporal and spatial variation in the distribution of epineustonic competent larvae of Concholepas concholepas along the central coast of Chile

Abstract

The abundance of competent epineustonic larvae of the gastropod Concholepas concholepas (Gastropoda: Muricidae) in nearshore waters at 2 sites along the central coast of Chile was examined through monthly plankton tows from July 1999 to June 2000. Larvae were found in plankton collections from July 1999 to February 2000 with maximum abundance in September and October. Settlement in artificial collectors deployed onshore on the lower intertidal zone showed the same unimodal pattern with a settlement peak during October and November. Variation in larval distribution among sampling dates was related to the occurrence of north-south winds. We found that C. concholepas larvae were more abundant closer to shore after moderate southerly wind periods than on calm days, probably because of the shoreward advection of the upper sea surface layer. While sampling during a strong coastal upwelling event (produced by strong southwesterly winds), C. concholepas larvae were only found in the upwelled waters between the front and the coast. This unusual pattern contrasts with what would be expected for typical epineustonic larvae, suggesting the existence of a mechanism of transport or retention by which C. concholepas larvae stay near coastal settling areas, thus avoiding offshore dispersion