Feeding ofPseudechinus magellanicus(Philippi, 1857) (Echinoidea: Temnopleuridae) in the SW Atlantic Coast (Argentina)

Abstract

Gut contents of Pseudechinus magellanicus collected from different habitats from Buenos Aires to Ushuaia were analyzed. In mussel beds off the Province of Buenos Aires at 50 m depth, the most important food items were Mytilus edulis platensis spat. In communities without Mytilus, food preferences were barnacles, foraminiferans, polychaetes and algae. In beds of the mytilid Aulacomya atra at a depth of 5-10m, main food items were oyster shell fragments and different algae: Rodophyta (leafy algae), Ectocarpus sp., and other algae. In Ushuaia the sea urchins preyed on ostracods, foraminiferans and algae. Multidimensional scaling ordination analyses showed that the diet of P. magellanicus depends mostly on the kind of inhabited substrate. Our data indicate that P. magellanicus from Argentina is omnivorous, consuming any available food resource: they capture drift algae with the aboral tube feet, graze on sessile algae, and prey on other animals. The results suggest that the species play an important role in the community structure of the circa-littoral beds of Mytilus edulis platensis, mainly through an intense predation on bivalve spat.