- Cyanobacteria are gram-negative, phototrophic bacteria that evolved more than 2.5 billion years ago. They can be found in aquatic, terrestrial and marine environments worldwide. They are especially successful in extreme habitats, such as the permanently cold environments of the Polar regions due their striking array of adaptation mechanisms to withstand the extreme conditions of permanently cold environments. Cyanobacteria have various physiological traits and adaptations, that allows them to cope with extreme Arctic conditions, like freezing, osmotic stress and dessication, and high UV-radiation.
- Cyanobacteria are an important part of Arctic microbiological communities, and some of the most common taxa in terrestrial and benthic freshwater environments of the Arctic. Even though they are microscopic, we can regularly see them with bare eyes in the form macroscopic biofilms, terrestrial crusts on stones and soil and benthic mats in ponds, lakes and streams. Especially aquatic, benthic cyanobacteria can reach very high biomass accumulations as mm- to cm-thick cyanobacterial mats.
- They are important primary producer in Arctic terrestrial soil, rock and freshwater environments. They are also some of the few organisms that can fixate nitrogen, making it available to other organisms – often as symbiotic partner in e.g. lichen. As such, they contribute to both the carbon and nitrogen cycling in Arctic systems.
- In Arctic freshwater environments, the conditions limit the growth of aquatic plants, macrophytes and bryophytes, and cyanobacteria are often crucial contributor to primary production and Arctic benthic freshwater food webs. This also includes glacial habitats such as cryoconite holes.
- Cyanobacteria are also widespread in terrestrial soil environments, and there role is especially important where conditions are harsh – e.g. as crusts on stones and soil or hypolithic communities below rocks and stones that can be abundant in the Arctic and contribute to carbon and nitrogen cycling in polar deserts. Cyanbacteria are often the primary colonisers of newly exposed permafrost soils and can help increases both soil stability and nutrient concentrations.
- Cyanobacteria can also form partnerships with several types of organisms, like in lichens and with mosses. In such partnerships, they often supply nitrogen, but in some cases also carbon, to their partner. Cyanobacteria containing lichens are an important and abundant part of the soil biodiversity in the Arctic, and also epiphytic cyanobacteria-moss associations are common.
- When cyanobacteria enrich soil with fixated nitrogen as partners in lichen or with bryophytes, they can facilitate the growth of other microbial communities and help the colonization and growth of higher plants in nitrogen depleted Arctic environments.
- A diverse assemblage of taxa has been described from Arctic environments. Cyanobacteria get transported in locally in the Arctic, and there seems to be both endemic and globally distributed cyanobacteria. However, further evidence is needed before a conclusions can be drawn on their global biogeographic distribution.
