Quantitative analysis of soft bottoms infaunal macrobenthic polychaetes from South Shetland Islands (Antarctica)

The macrobenthic infaunal communities of polychaetes from South Shetland Islands (Antarctica) were studied. A total of 3700 specimens of polychaetes belonging to 29 families were identified; 89 species are herein reported. The families Maldanidae and Terebellidae were the most abundant and frequent in the studied areas. The polychaete communities was studied in two ways: Comparison among sampling stations (diversity, richness and eveness; similarity in faunistic composition and determination of the taxa indicative of dissimilarity between groups of stations) and relationships between community structure and abiotic parameters. Only three species present values of abundance over 5%: Maldane sarsi antarctica (44.85%), Asychis amphiglypta (9.75%), and Sternaspis scutata (6.35%). The species which appeared at least at 50% of the stations were: Lumbrineris kerguelensis cingulata and hi. sarsi antarctica (78.26%), Chaetozone setosa (65.22%), Amphicteis gunneri antarctica (60.87%), Scalibregma inflatum (56.52%), Axiothella antarctica, Rhodine intermedia and Euchone pallida (52.17%). Density of specimens ranged between 96.7 ind m(-2) and 2910 ind m(-2). The analysis of similarity shows three groups of stations: the first group is composed of deep stations, the second of shallow stations around the coast of Livingston Island, and the third of stations located inside Foster Bay, Deception Island. The analysis of environmental parameters showed that the variable which grouped the stations in a consistent manner was the percentage of organic matter with depth, however, the influence of the environmental factors on the communities of polychaetes was only moderate.