Abstract
The numerous perennial meltwater ponds distributed throughout Antarctica represent diverse and productive ecosystems central to the ecological functioning of the surrounding ultra oligotrophic environment. The dominant taxa in the pond benthic communities have been well described however, little is known regarding their regional dispersal and local drivers to community structure. The benthic microbial communities of 12 meltwater ponds in the McMurdo Sound of Antarctica were investigated to examine variation between pond microbial communities and their biogeography. Geochemically comparable but geomorphologically distinct ponds were selected from Bratina Island (ice shelf) and Miers Valley (terrestrial) (<40 km between study sites), and community structure within ponds was compared using DNA fingerprinting and pyrosequencing of 16S rRNA gene amplicons. More than 85% of total sequence reads were shared between pooled benthic communities at different locations (OTU0.05), which in combination with favorable prevailing winds suggests aeolian regional distribution. Consistent with previous findings Proteobacteria and Bacteroidetes were the dominant phyla representing over 50% of total sequences; however, a large number of other phyla (21) were also detected in this ecosystem. Although dominant Bacteria were ubiquitous between ponds, site and local selection resulted in heterogeneous community structures and with more than 45% of diversity being pond specific. Potassium was identified as the most significant contributing factor to the cosmopolitan community structure and aluminum to the location unique community based on a BEST analysis (Spearman's correlation coefficient of 0.632 and 0.806, respectively). These results indicate that the microbial communities in meltwater ponds are easily dispersed regionally and that the local geochemical environment drives the ponds community structure.
Highlights
Antarctic aquatic mats and associated sediments harbor diverse microbial communities crucial to nutrient cycling (Bowman et al, 2000) and are the presumed dominant source of terrestrial biomass outside of coastal areas (Moorhead et al, 2003; Wood et al, 2008)
Benthic Microbial Community Structure in Meltwater Ponds Inter-pond benthic bacterial Automated Ribosomal Intergenic Spacer Analysis (ARISA) community structure based on a non-metric MDS plot (Figure 3) had a broad distribution with little clustering based on location (Bratina or Miers)
Benthic community structure of individual ponds based on operational taxonomic units (OTUs) abundance was heterogeneous (
Summary
Antarctic aquatic mats and associated sediments harbor diverse microbial communities crucial to nutrient cycling (Bowman et al, 2000) and are the presumed dominant source of terrestrial biomass outside of coastal areas (Moorhead et al, 2003; Wood et al, 2008). Smaller than their well-studied lake counterparts, meltwater ponds derived from local ice and snow melt, are more abundant throughout the continent, providing individually distinct geochemical environments. Within 1 km of an established field camp are a series of previously studied ponds of variable size, depth, age, and chemistry
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