Estructurada de las comunidades bontónicas en tres sitios de las islas Shetland del sur (Antártida): Patrones de diversidad, composición y tamaños corporales

Abstract

Antarctic benthic communities are extremely distinctive. They are characterized by the dominance of suspension feeders, the lack of durophagous predators, the presence of gigantism in some taxaand high values of diversity. The aim of this study is to compare the structure of benthic communities in three sites with different topographic characteristics. During the 2011 Antarctic Summer Expedition on board of R/V ARA Puerto Deseado representative benthic communities samples were taken between 156-246 m depth. All organisms were preserved in a 4% formaldehyde solution until laboratory examination. Abundance, biomass and diversity were quantified for each sample. Then histograms to evaluate the relationship between abundance and biomass were done and a multivariate analysis (cluster) was performed. A total of 1772 organisms were recorded comprising more than 12 classes of invertebrates. The ecological parameters (richness, diversity, evenness and dominance) varied considerably between the three samples. The cluster analysis grouped two sites located at the north of the archipelago and separated the locality from Deception Island. The last sample showed the highest abundance values but the lowest of diversity which could be associated with the volcanic activity of the area and the secondary succession that prevails in the zone. The other two samples showed similar values of diversity but the specific composition was different. This situation is interpreted based in the existence of local communities that respond principally to the high habitat heterogeneity which is the result of complex glacial geomorphological basins resulting in differences in the substrate type, and consequently in the associated biota.