Biodiversity of the cyanobacterial community in the foreland of the retreating glacier Midtre Lovènbreen, Spitsbergen, Svalbard

In the high Arctic, soils are commonly nutrient poor and nitrogen is often the limiting factor. There, cyanobacteria play an important role because they can overcome this limitation with their ability to fix atmospheric nitrogen and carbon dioxide. The present study is part of an investigation of the spatial and temporal succession of the cyanobacterial community during the process of colonisation of a deglaciated soil. In summer 2003, during three weeks of field work in Svalbard, seven sites along a chronosequence on the foreland of the retreating glacier Midtre Lovènbreen (Ny-Ålesund, 79ºN/12ºE), were sampled. The sites on the chronosequence had been previously characterised for the different time they came out of the ice. We analysed the biodiversity of the cyanobacterial community beginning from bare newly exposed soils near the glacier front down to mature vegetation that has developed for about 2000 years since ice retreated. A polyphasic approach, integrating morphological and molecular analyses of environmental samples and cultured strains was applied. Since now, 40 cyanobacterial strains were isolated and microphotographed; their morphological characterisation at genus level was carried out. The work in term of strain isolation, especially for site 7, is still in course. A phylogenetic analysis of selected cyanobacterial strains representing the morphological variability found in the environment was also done. Molecular fingerprints of the cyanobacterial community were compared with morphological observations and with the isolated strains obtained from the chronosequence. The obtained results aim to new insights on the diversity and role of cyanobacteria in the Arctic.