BiodivERsA-Climate change impacts on Arctic soil and lake microbiomes

Nowhere is climate change more visible than in the Arctic, making it the most critical reference region for the detection and understanding of global change, and its effects on biodiversity and ecosystem functioning. The physical and chemical attributes of Arctic soils and lakes are very sensitive to climate change because of their close proximity to freezing, implying critical limits to snow cover, albedo, ice extent, phenology and light availability. It follows that relatively small climatic changes can have profound impacts on Arctic ecosystems and their biota. This rapid response is also due to the fact that biogeochemical cycling and ecosystem functioning in Arctic environments are to a large extent controlled by microorganisms from all domains of life. The CLIMARCTIC project was aimed at studying the effects of climate change on the diversity and genetic functional attributes (nutrient and carbon cycling) of a high-Arctic terrestrial microbiome in soils, wetlands and lakes. To achieve this, we studied the diversity and functional genomic make-up of tundra and their substrate soils in two transects along a moisture gradient in Ny-Ålesund (Svalbard) using high-throughput DNA and RNA sequencing. This was combined with laboratory and field experiments and fossil DNA analysis to assess the effect of seasonal and long-term changes in temperature and precipitation on tundra and lake microbiomes. As such, CLIMARCTIC has developed a valuable platform to study the impact of future climate and environmental changes on high-Arctic tundra ecosystems.

Prosjektet har ledet til internasjonalt forskningssamarbeid og gitt data viktige for arktiske klimamodeller. Resultater har vært formidlet til arktiske interesseorganisasjoner og forvaltning. Prosjektet har styrket det terrestre flaggskipet i Ny-Ålesund, Svalbard.

CLIMARCTIC is aimed at studying the potential effects of climate change on microbial diversity and genetic functions in relation to nutrient and carbon cycling of High Arctic communities in soils, wetlands and lakes. This will be achieved by a combination of paleolimnological analyses, field and laboratory experimental studies. The first will make use of lake sediment cores and will provide insights into the response of these ecosystems to past climate changes. For the experiments, we will select samples along environmental gradients and seasons in Svalbard (Ny-Ålesund, research platform). The biodiversity in situ will be studied using classical microbiology techniques combined with modern molecular methods as well as chemical analysis of the photosynthetic pigments. This information will be combined with laboratory experiment to study nutrient and carbon cycling and microbial gene expression. Combined, these data will be used to develop a conceptual model of the food webs of a dry and wet tundra Arctic system. The field experiment will make use of snow fences to assess the effect of increased winter precipitation on the soil ecosystems. The laboratory experiments will address the effect of hydrological changes from altered precipitation patterns on gene expression and carbon cycling. We will also quantify the conversion rates between the different chemical forms of the major nutrients in field and laboratory experiments. During the three field campaigns - including one during winter - we will measure snow depth and light climate and analyse the photosynthetic efficiency, the respiration and the methane production in a natural wet and dry tundra site and in the plots with altered snow depth. These recent data will be integrated with long-term changes in nutrient, organic carbon content and food web structure to assess the responsiveness, resilience and rates of change of the lakes and their catchments during the past 2000 years.