Benthic decapod crustaceans associated with captures of Munida spp. (Decapoda: Anomura) in the Beagle Channel, Argentina

Abstract

Benthic decapod crustacean assemblages in the Beagle Channel are dominated by the galatheid crabs Munidasubrugosa and Munida gregaria. This study deals with the bathymetric and spatial distribution, density and diversity of the assemblage of decapod species that co-occur with Munida spp. in the Beagle Channel. A total of 131 samples were obtained using an epibenthic trawl from February 1999 to December 2000. They were taken monthly from two depth strata separated by the 40 m isobath (range: 4-262 m), and from three different sites: Bahía Lapataia, Ushuaia and Punta Segunda. Sixteen of the 36 recorded species of decapod crustaceans from the Beagle Channel were caught. Munidasubrugosa and M. gregaria contributed 94% to the total decapod material. Of the remaining 6%, Austropandalusgrayi (Caridea) was the most abundant species, constituting 43% of the non-galatheid decapod fraction. Some species, namely Paguruscomptus and Eurypodius spp., were characteristic of shallow waters (<40 m), while others like Campylonotus semistriatus occurred in deeper waters (> 40 m). The average density and diversity of non-galatheid decapods varied with depth and location. Decapod diversity correlated positively with the density of algae and polychaete tubes. The influence of three-dimensional bottom structure on decapod diversity in the Beagle Channel is discussed.