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

The macrobenthic infaunal communities of polychaetes from South Shetland Is lands (Antarctica) were studied. A total of 3700 specimens of polychaetes b elonging to 29 families were identified; 89 species are herein reported. Th e families Maldanidae and Terebellidae were the most abundant and frequent in the studied areas. The polychaete communities was studied in two ways: C omparison among sampling stations (diversity, richness and eveness; similar ity in faunistic composition and determination of the taxa indicative of di ssimilarity between groups of stations) and relationships between community structure and abiotic parameters. Only three species present values of abu ndance over 5%: Maldane sarsi antarctica (44.85%), Asychis amphiglypta (9.7 5%), 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 antarc tica (60.87%), Scalibregma inflatum (56.52%), Axiothella antarctica, Rhodin e intermedia and Euchone pallida (52.17%). Density of specimens ranged betw een 96.7 ind m(-2) and 2910 ind m(-2). The analysis of similarity shows thr ee groups of stations: the first group is composed of deep stations, the se cond of shallow stations around the coast of Livingston Island, and the thi rd of stations located inside Foster Bay, Deception Island. The analysis of environmental parameters showed that the variable which grouped the statio ns in a consistent manner was the percentage of organic matter with depth, however, the influence of the environmental factors on the communities of p olychaetes was only moderate.