Diets of deep-sea brachyuran crabs in the Western Mediterranean Sea

Abstract

This study examines the feeding habits of Paromola cuvieri (Risso, 1816) and Geryon longipes A. Milne Edwards, 1881, the only two common deep-sea brachyuran crabs inhabiting the bathyal mud assemblages in the Catalan Sea (Western Mediterranean). Samples were obtained by bottom trawls at depths between 360 and 1871 m during 1983 to 1992. Both species had highly diverse diets, but very low feeding activity, as reflected by the high proportion of empty stomachs. Both characteristics may be important factors enabling deepsea crabs to adapt to bathyal zones, where trophic resources are scarce. The most important food items found in P. cuvieri were fish remains (teleost, sharks) and benthic decapods (Monodaeus couchii, Munida tenuimana). Scavenging activity plays an important role in this species. The diet of G. longipes included a broad range of benthic invertebrates. In the upper middle slope, the bivalve Abra longicallus, decapods (Calocaris macandreae and Monodaeus couchii), echinoderms and polychaetes were the dominant prey, with epibenthic peracarids as a secondary resource. On the lower middle slope, the incidence of decapod crustaceans (C. macandreae, Pontiphilus norvegicus) and peracarids in the diet declined. Small macrobenthic prey (glycerids, cumaceans or amphipods) were rare in the diet of both species, in accordance with the large size of the crab specimens studied. The absence of preferred prey items and the lack of food items of an optimum size on the lower slope may contribute to the progressive decline in abundance of P. cuvieri and G. longipes with increasing depth.