Unintended backpackers: bio-fouling of the invasive gastropod Rapana venosa on the green turtle Chelonia mydas in the Rio de la Plata Estuary, Uruguay

Here we report the first observations of the rapa whelk Rapana venosa massively bio-fouling immature green turtles Chelonia mydas. From November 2004 to July 2011, we examined 33 green turtles with rapa whelks attached to their carapaces in Uruguayan waters. The number of attached rapa whelks ranged from 1 to 49 individuals, representing up to 20 % of turtle weight. This previously unrecorded interaction may be of global importance to green turtles conservation because (a) immature green turtles from distant breeding populations utilize insular and coastal waters of the Rio de la Plata estuary and Atlantic coast of Uruguay as developmental and foraging habitats and (b) attached whelks may reduce green turtle fitness by reducing buoyancy, increasing drag, and causing severe injuries to the carapace.