A meromictic lake has layers of water which do not intermix. The deepest layer of water in such a lake does not contain any dissolved oxygen. The layers of sediment at the bottom of a meromictic lake remain relatively undisturbed because there are no living organisms to stir them up.

This type of lake may form for a number of reasons:

• the basin is unusually deep and steep-sided compared to the lake's surface area
• the lower layer of the lake is highly saline and so denser than the higher levels of water

Bacteria which use sulfur compounds in photosynthesis rather than oxygen can be found in some meromictic lakes.

Occasionally carbon dioxide (CO₂) or other dissolved gasses can build up relatively undisturbed in the lower layers of a meromictic lake. When the stratification is disturbed, as could happen due to an earthquake, a limnic eruption may result. A notable event of this type took place at Lake Nyos in 1986, causing nearly 1,800 deaths.

Some examples of meromictic lakes are:

• Soap Lake in Washington.
• Green Lake and Round Lake, in Green Lakes State Park, 13km east of Syracuse, New York
• Crawford Lake near Toronto, Ontario
• Pink Lake in Gatineau Park, Quebec
• McGinnis Lake in Petroglyphs Provincial Park, Ontario
• Mahoney Lake in the Okanagan Valley, British Columbia
• Lake Fidler, beside the Gordon River in Tasmania's Wilderness World Heritage Area, Australia.
• Salsvatnet, Kilevann, Tronstadvatn, Birkelandsvatn, Rørholtfjorden, Botnvatn, Rørhopvatn and Strandvatn lakes in Norway are meromictic.
• Lake Nyos in Cameroon
• Irondequoit Bay (Rochester, NY) is also considered meromictic. Use of road salt has been cited as the main reason for its change.

The Black Sea is also considered to be meromictic.

External links

• Lake Fidler revived

Lakes

Meromiktisk