Changes in salinity and temperature drive marine bacterial communities’ structure at Potter Cove, Antarctica

Abstract

Coastal areas of the West Antarctic Peninsula (WAP) constitute a rich and biodiverse marine zone. Despite these ecosystems being supported by the microorganism’s activity, the structure of microbial communities is insufficiently studied. As WAP is the area most affected by global warming worldwide, the increased glacier melting caused by the global warming and the consequent increase of the water runoff could be deeply affecting these microbial communities. To advance knowledge about the structure of microbial communities and its response to the environmental factors, a full-year study of marine bacterioplankton was conducted at Potter Cove, Antarctica. Multivariate analysis based on denaturing gradient gel electrophoresis (DGGE) and environmental data revealed a seasonal pattern in the structure of the bacterioplankton community, with spring–summer clustering separately from autumn–winter samples. Salinity, temperature and particulated matter were the main environmental driving forces. Based on the seasonal patterns, five bacterial clone libraries were performed from three sampling sites (E1, inner cove; E2, outer cove; and E3, mouth of a creek). Phylogenetic analysis of libraries generated 301 operational taxonomic units (OTUs), revealing the enormous richness and high diversity of these communities. Proteobacteria (68%), Bacteroidetes (20%) and Actinobacteria (8%) were the most represented phyla. During summer, bacterial community from E1 resembled that observed in E3, whereas during winter it resembled the E2 community. Results evidenced the influence of glacial meltwater input and showed the high variability of the bacterioplankton from inner cove. This study contributes to the better understanding of the structure of the Potter Cove marine ecosystems and could be reflecting the behavior of other similar ecosystems from WAP