Spatial and temporal patterns of bacterial communities in a high Arctic glacier foreland

Climate change disproportionally affects the Arctic, and an important consequence is the accelerated loss of Arctic glaciers. On these newly exposed glacier moraines microorganisms have key roles in soil development, nutrient cycling, and plant growth. However, while the ecology of plant communities in terms of species succession and diversity has been extensively studied, little is known about bacterial communities in glacier forelands. This thesis contains three chapters in which the findings and ideas presented advance understanding of bacterial succession and bacterial diversity in High Arctic terrestrial habitats. Chapter 2 presents the results of a study done to rigorously test whether bacterial succession occurred in the glacier foreland of Midre Loven glacier, Svalbard, Norway. Despite the high spatial heterogeneity that exists in soils we were able to show that bacterial succession occurred and significantly differed as a function of soil depth. In chapter 3, we reviewed recent advances in terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes; a method commonly used to fingerprint microbial communities that was employed in the studies described in Chapter 2. This review focused on the statistical methods used for the analysis of T-RFLP data. Presented in chapter 4 are the results of an intensive and extensive assessment of bacterial diversity, which includes estimates of phylotype richness, evenness, turnover rate, and the taxa present at the different times since glacier retreat. We found that bacterial diversity at all locations sampled was remarkably high, and that the rates of species turnover were particularly high in younger sites of the glacier foreland. Overall this thesis is a detailed assessment of spatial and temporal patterns of bacterial communities in a High Arctic glacier foreland. Systematic studies such as these can serve as the basis for understanding the role of bacterial communities in High Arctic terrestrial ecosystems.