SPATIAL DIMENSIONS AND IMPACTS OF PERMAFROST DISTURBANCE ON MICROBIAL COMMUNITY COMPOSITION IN HIGH ARCTIC ECOSYSTEMS

Climate change is substantially affecting permafrost dynamics, hydrological conditions and landscape stability in High Arctic ecosystems. These changes will correspondingly influence watershed nutrient pathways and availability, mobilization and deposition of sedimentary materials, water quality, that ultimately result in dramatic changes to terrestrial and aquatic ecosystem function and global biogeochemical cycles. To date, inventories of microbial community composition in permafrost landscapes remain poorly defined. This study investigates the microbial community composition of three different Arctic permafrost environments (e.g., streams, thaw ponds, groundwater seeps) on the Sabine Peninsula, Melville Island, Nunavut. Our 16S rRNA gene pyrosequencing results were compared to physiographic and geochemical attributes of the system including: geologic substrate, soil moisture, vegetation, soil type, pH, and major cation and anion concentrations using NMDS (non-metric multidimensional scaling). Chloride and sulfate concentrations and deuterium excess values were used to determine the source of water, solute, and nutrients to streams, thaw ponds, and groundwater seeps. High Arctic ecosystems are an important component of major transitions occurring between Earth-surface environments and a rapidly emerging low-temperature terrestrial biosphere. Permafrost disturbance generates new surface and subsurface pathways for mobilization of solute and nutrients. These landscape scale changes will accelerate biogeochemical fluxes downstream, impact the composition of microbial communities, and ultimately alter the flow of energy and materials through terrestrial and aquatic ecosystems on Earth.