Ice algae

Microbial life in sea ice is extremely diverse,[2][3][4] and includes abundant algae, bacteria and protozoa.

[5][6] Algae in particular dominate the sympagic environment, with estimates of more than 1000 unicellular eukaryotes found to associate with sea ice in the Arctic.

Melosira arctica, which forms up to meter-long filaments attached to the bottom of the ice, are also widespread in the Arctic and are an important food source for marine species.

[14] To survive in the harsh sea ice environment, organisms must be able to endure extreme variations in salinity, temperature, and solar radiation.

Sea ice algae play a critical role in primary production and serve as part of the base of the polar food web by converting carbon dioxide and inorganic nutrients to oxygen and organic matter through photosynthesis in the upper ocean of both the Arctic and Antarctic.

Other groups, such as the dinoflagellates, which also bloom in the spring/summer, have been shown to maintain low cell numbers in the water column itself, and do not primarily overwinter within the ice.

[26] Climate change and warming of Arctic and Antarctic regions have the potential to greatly alter ecosystem functioning.

[28] Changes in multiyear ice volume[29] will also have an impact on ecosystem function in terms of bloom seeding source adjustment.

Reduction in MYI, a temporal refugia for diatoms in particular, will likely alter sympagic community composition, resulting in bloom initialization that derives from species that overwinter in the water column or sediments instead.

[25] Because sea ice algae are often the base of the food web, these alterations have implications for species of higher trophic levels.

Because clouds impact precipitation and the amount of solar radiation reflected back to space (albedo), this process could create a positive feedback loop.

[31] Cloud cover would increase the insolation reflected back to space by the atmosphere, potentially helping to cool the planet and support more polar habitats for sea ice algae.

As of 1987, research has suggested that a doubling of cloud-condensation nuclei, of which DMS is one type, would be required to counteract warming due to increased atmospheric CO2 concentrations.

There are a number of organisms whose value as proxies for the presence of sea ice has been investigated, including particular species of diatoms, dinoflagellate cysts, ostracods, and foraminifers.

Variation in carbon and oxygen isotopes in a sediment core can also be used to make inferences about sea ice extent.

Each proxy has advantages and disadvantages; for example, some diatom species that are unique to sea ice are very abundant in the sediment record, however, preservation efficiency can vary.

[36] Alpine freshwater ice and snow which can last over half a year has been found to support an overall higher microbial biomass and algal activity than the lake water itself as well as specific predatory species of ciliates only found in the slush layer of the ice and snow interface.

The species found in these habitats are distinct from those associated with sea ice because the system is freshwater and the algae are pigmented.

For example, cryosestic communities are specifically found on the surface of glaciers where the snow periodically melts during the day.

[41] Algae blooms have been shown to appear on glaciers and ice sheets once the snow had begun to melt, which occurs when the air temperature is above the freezing point for a few days.

[41] Climate change is affecting both the start of the melting season and also the length of this period, which will lead to an increase in the amount of algae growth.

As the ice/snow begins to melt the area the ice covers decreases which means a higher portion of land is exposed.