Diversity of planktonic gastropods from western Baja California Peninsula assessed by 18S rDNA sequences

The study of planktonic mollusks is a relevant element to understand the dynamics of the benthic communities under present and future environmental conditions. We present the description of the biodiversity of planktonic gastropods at 2 sampling sites on the Pacific coast of the Baja California Peninsula, Mexico. Organisms collected from plankton tows at 2 locations (Cabo Tosco, n = 89 and La Bocana, n = 213) were sequenced for a portion of the 18S rDNA gene. High diversity was registered, with 71 Molecular Operational Taxonomic Units (MOTUs), which contrasts with the low phenotypic diversity of stereoscopic images. Differences in community composition between and within sampling sites indicate that planktonic gastropod distribution is not random but probably modulated by micro-environmental processes such as currents or biological events. The presence of non-gastropod sequences within some shells (n = 6) suggests their use as carriers of eggs or larvae of other taxa.