Abundance of the reef-building Petaloconchus varians (Gastropoda: Vermetidae) on intertidal rocky shores at Ilha Grande Bay, southeastern Brazil

A recent study reveals that reefs formed by the vermetid gastropod Petaloconchus varians are becoming dominant features of intertidal rocky shores in Ilha Grande Bay, southeastern Brazil. Previously thought to have declined in the region mid-20th century, P. varians now constructs extensive reefs with densities ranging from 620 to 2,559 individuals per 100 cm² and weights up to 1,500 g per 100 cm². These reefs form wide belts (38 cm to 2 m) along the middle intertidal zone across sites with varying wave exposure and slopes (10° to 46°). The study suggests a potential resurgence of P. varians, contributing critical insights into local ecological dynamics within this UNESCO-listed site.

BREVES, A., SZÉCHY, M. T. M. D., LAVRADO, H. P., & JUNQUEIRA, A. O. R. (2017). Abundance of the reef-building Petaloconchus varians (Gastropoda: Vermetidae) on intertidal rocky shores at Ilha Grande Bay, southeastern Brazil. Anais Da Academia Brasileira de Ciências, 89(2), 907–918. https://doi.org/10.1590/0001-3765201720160433