Ice algae terrestrial ice algae occur in freshwater systems, the species composition differs greatly from that of sea ice algae. These communities are significant in that they often change the color of glaciers and ice sheets, impacting the reflectivity of the ice itself. Microbial life in sea ice is extremely diverse, and includes abundant algae, bacteria and protozoa. Algae in particular dominate the sympagic environment, with estimates of more than 1000 unicellular eukaryotes found to associate with sea ice in the Arctic. Species composition and diversity vary based on location, ice type, and irradiance. In general, pennate diatoms such as "Nitschia frigida"
Lake Winnipeg algae threat fossil fuels, development of large urban populations, and an upsurge in land clearing and deforestation. Nitrogen and phosphorus loading from human activity has accelerated eutrophication of certain rivers, lakes, and wetlands in the U.S.A. resulting in loss of habitat, changes in biodiversity and, in some cases, loss of recreational potential. Lake Winnipeg suffers from the rapid absorption of the elements phosphorus, nitrogen, and carbon. Eutrophication processes fuel the growth of blue-green algae, also known by its more correct scientific name cyanobacteria. These bacteria normally appear green in color and can turn blue when the algae (bacteria) blooms are dying. As