CONICET | Buscador de Institutos y Recursos Humanos

In this study we describe the feeding biology of the exotic predatory whelk Rapana venosa from the Río de la Plata when offered representative coastal bivalves from both soft and hard bottoms. Furthermore, we estimate daily consumption rates using two mussel species commonly found on local rocky outcrops and artificial reefs. R. venosa gastropods (N = 21; shell height, SH = 45-117 mm) were obtained by trawling in the Río de la Plata and kept in controlled laboratory settings. To describe its feeding behavior, ten potential prey species were offered to the gastropods, including Mactra isabelleana, Erodona mactroides, Pitar rostratus, Donax hanleyanus, Mesodesma mactroides, Mytilus platensis, Brachidontes rodriguezi, Mytella charruana, Amiantis purpurata, and Crassostrea gigas. All prey species were consumed. The empty shells left after consumption frequently showed broken shells and rasp signatures in the edges, suggesting a prey attack by marginal chipping or a similar mechanism. This common pattern wasnt observed in A. purpurata or C. gigas. To explore potential effects of size on feeding behavior, the gastropods were separated in three size classes and offered M. platensis, B. rodriguezi, and M. charruana mussels. Small, intermediate, and large gastropods (< 60 mm, 60-90 mm and > 90 mm SH respectively) consumed comparable mussel size ranges. Small gastropods fed upon prey sizes up to 30% larger than their size, while large gastropods consumed the largest mussel offered (78 mm SH). To estimate daily consumption rates, the 21 gastropods were fed with M. platensis and B. rodriguezi in individual tanks during twelve days. They ate 1.45 ± 0.67 SD mussels and 0.68 ± 0.65 SD g per day per gastropod. The proportion of tissue wet weight consumed didnt changed with prey species, but varied between the size classes of R. venosa. Small (< 60 mm) and intermediate (60-90 mm) gastropods consumed a similar proportion of prey tissue (up to 12% of their tissue wet weight). On the contrary, large gastropods (> 90 mm) ate up to 5% of their tissue wet weight. This work is the first report of R. venosa feeding behavior and daily consumption rates in Argentina. The gastropods succeeded in attacking and feeding upon a broad variety of local bivalve species characterized by noticeable differences in shell shape, size, and life habits.

enviar mensaje