Large-scale geographic patterns of pelagic copepods in the southwestern South Atlantic.

We compiled an extensive dataset of copepod presence/absence data to define ecoregions in the southwestern South Atlantic (33°S–55°S) and to examine their relationships to water mass characteristics. We also investigated the role of mesoscale fronts in determining the boundaries of the ecoregions. Finally, we compared copepod distributions with previously defined biogeographical provinces in the southwestern South Atlantic. The regional copepod community is organized into six assemblages that occupy distinct areas of the shelf, the shelfbreak, and the oceanic realm. These areas are characterized by different water masses. In general, the spatial configuration of the ecoregions matches that of the previously defined regional biogeographic provinces and marine fronts seem to act as boundaries between the ecoregions. • Ecoregions based on copepods assemblages relate to water mass characteristics. • Marine fronts constitute boundaries of the ecoregions. • Ecoregions match the biogeographic provinces of the southwestern South Atlantic. [ABSTRACT FROM AUTHOR]