Arctic permafrost coasts are sensitive to changing climate. The lengthening open water season and the increasing open water area are likely to induce greater erosion and threaten community and industry infrastructure as well as dramatically change nutrient pathways in the near-shore zone. The shallow, mediterranean Arctic Ocean is likely to be strongly affected by changes in currently poorly observed arctic coastal dynamics. We present a geomorphological classification scheme for the arctic coast, with 101,447 km of coastline in 1,315 segments. The average rate of erosion for the arctic coast is 0.5 m year −1 with high local and regional variability. Highest rates are observed in the Laptev, East Siberian, and Beaufort Seas. Strong spatial variability in associated database bluff height, ground carbon and ice content, and coastline movement highlights the need to estimate the relative importance of shifting coastal fluxes to the Arctic Ocean at multiple spatial scales.

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A combination of culture-dependent and culture-independent methodologies (Bacteria and Archaea 16S rRNA gene clone library analyses) was used to determine the microbial diversity present within a geographically distinct high Arctic permafrost sample. Culturable Bacteria isolates, identified by 16S rRNA gene sequencing, belonged to the phyla Firmicutes, Actinobacteria and Proteobacteria with spore-forming Firmicutes being the most abundant; the majority of the isolates (19/23) were psychrotolerant, some (11/23) were halotolerant, and three isolates grew at -5 degrees C. A Bacteria 16S rRNA gene library containing 101 clones was composed of 42 phylotypes related to diverse phylogenetic groups including the Actinobacteria, Proteobacteria, Firmicutes, Cytophaga - Flavobacteria - Bacteroides, Planctomyces and Gemmatimonadetes; the bacterial 16S rRNA gene phylotypes were dominated by Actinobacteria- and Proteobacteria-related sequences. An Archaea 16S rRNA gene clone library containing 56 clones was made up of 11 phylotypes and contained sequences related to both of the major Archaea domains (Euryarchaeota and Crenarchaeota); the majority of sequences in the Archaea library were related to halophilic Archaea. Characterization of the microbial diversity existing within permafrost environments is important as it will lead to a better understanding of how microorganisms function and survive in such extreme cryoenvironments.

SummaryCulture-dependent and culture-independent methods were used in an investigation of the microbial diversity in a permafrost/massive ground ice core from the Canadian high Arctic. Denaturing gradient gel electrophoresis as well as Bacteria and Archaea 16S rRNA gene clone libraries showed differences in the composition of the microbial communities in the distinct core horizons. Microbial diversity was similar in the active layer (surface) soil, permafrost table and permafrost horizons while the ground ice microbial community showed low diversity. Bacteria and Archaea sequences related to the Actinobacteria (54%) and Crenarchaeota (100%) respectively were predominant in the active layer while the majority of sequences in the permafrost were related to the Proteobacteria (57%) and Euryarchaeota (76%). The most abundant phyla in the ground ice clone libraries were the Firmicutes (59%) and Crenarchaeota (82%). Isolates from the permafrost were both less abundant and diverse than in the active layer soil, while no culturable cells were recovered from the ground ice. Mineralization of [1-14

The springs at Gypsum Hill and Colour Peak on Axel Heiberg Island in the Canadian Arctic originate from deep salt aquifers and are among the few known examples of cold springs in thick permafrost on Earth. The springs discharge cold anoxic brines (7.5 to 15.8% salts), with a mean oxidoreduction potential of ؊325 mV, and contain high concentrations of sulfate and sulfide. We surveyed the microbial diversity in the sediments of seven springs by denaturing gradient gel electrophoresis (DGGE) and analyzing clone libraries of 16S rRNA genes amplified with Bacteria and Archaea-specific primers. Dendrogram analysis of the DGGE banding patterns divided the springs into two clusters based on their geographic origin. Bacterial 16S rRNA clone sequences from the Gypsum Hill library (spring GH-4) were classified into seven phyla (Actinobacteria, Bacteroidetes, Firmicutes, Gemmatimonadetes, Proteobacteria, Spirochaetes, and Verrucomicrobia); Deltaproteobacteria and Gammaproteobacteria sequences represented half of the clone library. Sequences related to Proteobacteria (82%), Firmicutes (9%), and Bacteroidetes (6%) constituted 97% of the bacterial clone library from Colour Peak (spring CP-1). Most GH-4 archaeal clone sequences (79%) were related to the Crenarchaeota while half of the CP-1 sequences were related to orders Halobacteriales and Methanosarcinales of the Euryarchaeota. Sequences related to the sulfur-oxidizing bacterium Thiomicrospira psychrophila dominated both the GH-4 (19%) and CP-1 (45%) bacterial libraries, and 56 to 76% of the bacterial sequences were from potential sulfur-metabolizing bacteria. These results suggest that the utilization and cycling of sulfur compounds may play a major role in the energy production and maintenance of microbial communities in these unique, cold environments.