First detection of the non-indigenous gastropod Rapana venosa in the southernmost coast of Brazil

Abstract

The rapa whelk Rapana venosa is a predator of bivalves, native to Eastern Asia. It was first recorded outside its native distribution in 1946 in the Black Sea and since then has invaded estuarine and marine waters worldwide. The present findings increase the known geographic distribution of reproducing populations 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. We present the first records of R. venosa in the southernmost Brazilian coast (between Hermenegildo and Cassino Beaches, RS), based on 110 specimens, one as an epibiont associated with the green sea turtle Chelonia mydas. The majority of the specimens were found along Cassino beach, close to the inlet of the Patos Lagoon estuary (~32°S). 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 sea turtle conservation, given the observed potential for dispersal using turtle carapaces, which may affect their swimming and feeding. Our study contributes to the knowledge of bioinvasion in the Southwestern Atlantic coast.