First records of the invasive gastropod Rapana Venosa in the Southernmost coast of Brazil

Abstract

Rapana venosa (Valenciennes, 1846) is a predator of bivalves, native to Eastern Asia. It was first recorded outside of its native distribution in 1946 in the Black Sea, and has since invaded estuarine and marine waters worldwide. The present findings increase the known geographic distribution of reproducing populations that are distinct from the native population to eight regions: Black, Adriatic and Aegean seas, the coast of Brittany, the coast of the Netherlands, Chesapeake Bay, La Plata River estuary in Argentina-Uruguay and the southern Brazilian coast (present study). We present the first records of R. venosa in the southernmost Brazilian coast (between Hermenegildo and Cassino Beaches, RS), based on opercula, clusters of egg capsules, juvenile and adult shells, complete individuals with soft parts, and one as an epibiont associated with the green sea turtle Chelonia mydas (Linnaeus, 1758). Most of the specimens were found along the Cassino beach, close to the mouth of the Patos Lagoon estuary (about 32ºS). Despite the highly variable salinity in the estuarine area, R. venosa was able to invade this area, probably due to its high fecundity and fertility, fast growth rate and high tolerance to salinity and temperature variations, all characteristics of a successful invader. The presence of this species further to the north (about 800 km) of the La Plata River estuary shows that it is dispersing along the southwestern Atlantic. Its interaction with green turtles may be of global importance for the conservation of green turtles, given the observed potential for dispersal using turtle carapaces, which may affect their swimming and feeding.