Extreme Marine Environments

Abstract

The deep sea starts from below 200 m and is a region of high hydrostatic pressure, low temperature, and darkness. The deep biosphere below the surface of deep-sea sediments, the hypoxic and anoxic waters and sediments, polar environments, and hypersaline environments are other extreme environments. Obligate and facultative mycetaen marine fungi as well as labyrinthulomycetes inhabit such environments. Marine lignicolous fungi grow in wood deposited in the deep sea or lodged in polar waters. Fungi grow within calcareous shells of deep-sea molluscs. Aplanochytrids inhabit mesozooplankton in deep-sea waters. Fungi have been cultured from the deep biosphere, hypoxic and anoxic waters and sediments, polar waters, and sea ice and from salterns, the Dead Sea, and other hypersaline environments. Thraustochytrids are found in sea ice. Actively growing fungal hyphae have been detected in all extreme environments. Fungi have become adapted to conditions of extreme environments. Facultative marine fungi are adept at growing under high hydrostatic pressure and cold temperature and are found in deep-sea sediment humic aggregates. Fungi from OMZs are capable of denitrification. Many fungi, such as black yeasts and others from hypersaline environments, can successfully grow in extreme salinity conditions and adjust their intracellular osmotic potential by synthesizing polyols. Metagenomic studies have revealed a number of novel fungal lineages in all extreme environments.