Biogeography of Cyanobacteria in Antarctic Mats and Implication for Conservation

On the Antarctic continent, cyanobacterial mats are widespread in the lacustrine biotopes and they often dominate the phototrophic biomass. Their diversity and biogeography are poorly understood because most studies cover a limited geographic area or are based only on morphotypes. Therefore, cyanobacteria are not fully taken into account in the biological datasets used to delineate conservation biogeographic regions (ACBRs). Recently, we have shown by 454 pyrosequencing of cyanobacteria-specific 16S rRNA amplicons that their distribution across the lacustrine ecosystems could be explained by ecological parameters (e.g. salinity and dissolved organic carbon). In order to further test this hypothesis, we significantly increased the spatial coverage of our samples. Here, we describe the results of 16S rRNA amplicons Illumina sequencing of 98 cyanobacterial mat samples from 10 ACBRs. From the 16012393 raw reads, 713 OTUs were obtained by bioinformatics analysis. Preliminary results show that both ecological parameters and latitude could explain the patterns of cyanobacterial communities. Indeed, nonmetric multidimensional scaling shows that sub-Antarctic samples (Macquarie and Marion Islands) group with North-East Antarctic Peninsula samples, whereas more continental samples (e.g. East Antarctica, South Victoria Land) group together. These findings can form the basis for a better understanding and a more adequate conservation of lacustrine ecosystems in Antarctica.