Biogeography and biodiversity of gastropod molluscs from the eastern Brazilian continental shelf and slope.

Biogeographic distributional patterns of gastropods are proposed based on the species' geographic and bathymetric distribution. Samples were collected along the Brazilian continental margin between 18° S and 23° S, at 37 stations with depths from 20 m to 1,330 m. The analysis of the biogeographic distribution patterns confirmed the existence of a transitional zone from tropical to subtropical waters in the area of both the continental shelf and slope, suggesting a relationship with water mass circulation. We observed a high species turnover rate between the shelf and slope. The analysis of gastropod species distribution revealed a similar pattern on the shelf and slope and a large difference between shallow and deep-water faunas. [ABSTRACT FROM AUTHOR]