Specific microbial species can thrive in high-salinity environments that are inhospitable to most lifeforms, including some that are thought to contribute to the color of pink lakes. Some of these species enter a dormant state when desiccated, and some species are thought to survive for over 250 million years.
Hypersaline lake in the context of Messinian salinity crisis
The Messinian salinity crisis (also referred to as the Messinian event, and in its latest stage as the Lago Mare event) was an event in which the Mediterranean Sea went into a cycle of partial or nearly complete desiccation (drying-up) throughout the latter part of the Messinian age of the Miocene epoch, from 5.96 to 5.33 Ma (million years ago). It ended with the Zanclean flood, when the Atlantic reclaimed the basin.
Sediment samples from below the deep seafloor of the Mediterranean Sea, which include evaporite minerals, soils, and fossil plants, show that the precursor of the Strait of Gibraltar closed about 5.96 million years ago, sealing the Mediterranean off from the Atlantic. This resulted in a period of partial desiccation of the Mediterranean Sea, the first of several such periods during the late Miocene. After the strait closed for the last time around 5.6 Ma, the region's generally dry climate at the time dried the Mediterranean basin out nearly completely within a thousand years. This massive desiccation left a deep dry basin, reaching 3 to 5 km (1.9 to 3.1 mi) deep below normal sea level, with a few hypersaline pockets similar to today's Dead Sea. Then, around 5.5 Ma, wetter climatic conditions resulted in the basin receiving more fresh water from rivers, progressively filling and diluting the hypersaline lakes into larger pockets of brackish water (much like today's Caspian Sea). The Messinian salinity crisis ended with the Strait of Gibraltar finally reopening 5.33 Ma, when the Atlantic rapidly filled up the Mediterranean basin in what is known as the Zanclean flood.
An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for its growth. It may react negatively or even die in the presence of free oxygen. Anaerobic organisms do not use oxygen as a terminal electron acceptor in their respiration process to produce energy, but a less powerful oxidizing agent, such as nitrate, ferric ion, Mn(IV), sulfate or bicarbonate anions. In contrast, an aerobic organism (aerobe) is an organism that requires a sufficiently oxygenated environment to respire, produce its energy, and thrive. Because the anaerobic energy production was the first mechanism to be used by living microorganisms in their evolution and is much less efficient than the aerobic pathway, anaerobes are practically, de facto, always unicellular organisms (e.g. bacteria and archaea (prokaryotes), or protozoans (eukaryotes). However, a minuscule multicellular organism, with an exceptionally rare metabolism and surviving in a hypersaline brine pool in the darkness of the bottom of the Mediterranean Sea, has been recently discovered. Meanwhile, it remains a scientific curiosity, as the much higher energy requirements of most multicellular organisms cannot be met by anaerobic respiration. Most fungi (eukaryotes) are obligate aerobes, requiring oxygen to survive and grow; however, some species, such as the Chytridiomycota that reside in the rumen of cattle, are obligate anaerobes; for these species, anaerobic respiration is used because oxygen would disrupt their metabolism or kill them. The deep seafloor and its underlying unconsolidatedsediments ranks among the largest potential habitats for anaerobic microorganisms on Earth. Moreover, chemoautotroph microbes also thrive around hydrothermal vents, discharging hot water on the oceanseabed near mid-ocean ridges, where anaerobic conditions prevail. These microbes produce energy in the absence of sunlight or oxygen through a process called anaerobic respiration, whereby inorganic compounds and ions such as protons (H), elemental sulfur and its derivatives (SO2−4, S2O2−3), or ferric ions, are reduced to drive oxidative phosphorylation.
As of 2025, the lake's surface is 439.78 metres (1,443 ft) below sea level, making its shores the lowest land-based elevation on Earth. It is 304 m (997 ft) deep, the deepest hypersaline lake in the world. With a salinity of 342 g/kg, or 34.2% (in 2011), it is one of the world's saltiest bodies of water, 9.6 times as salty as the ocean—and has a density of 1.24 kg/litre, which makes swimming similar to floating. This salinity makes for a harsh environment in which plants and animals cannot flourish, hence its name. The Dead Sea's main, northern basin is 50 kilometres (31 mi) long and 15 kilometres (9 mi) wide at its widest point.
A salt lake or saline lake is a landlocked body of water that has a concentration of salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per liter). In some cases, salt lakes have a higher concentration of salt than sea water; such lakes can also be termed hypersaline lake, and may also be pink lakes on account of their color. An alkalic salt lake that has a high content of carbonate is sometimes termed a soda lake.
Salt lakes are classified according to salinity levels. The formation of these lakes is influenced by processes such as evaporation and deposition. Salt lakes face serious conservation challenges due to climate change, pollution and water diversion.
Lake Tuz (Turkish: Tuz Gölü meaning 'Salt Lake) is the second largest lake in Turkey with its 1,665 km (643 sq mi)surface area and one of the largest hypersaline lakes in the world. It is located in the Central Anatolia Region, 105 km (65 mi) northeast of Konya, 150 km (93 mi) south-southeast of Ankara and 57 km (35 mi) northwest of Aksaray. In recent years, Lake Tuz has become a hotspot for tourists. In October 2021, Lake Tuz temporarily dried up completely due to climate change and unsustainable irrigation practices.
A soda lake or alkaline lake is a lake on the strongly basic side of neutrality, typically with a pH value between 9 and 12. They are characterized by high concentrations of carbonate salts, typically sodium carbonate (and related salt complexes), giving rise to their alkalinity. In addition, many soda lakes also contain high concentrations of sodium chloride and other dissolved salts, making them saline or hypersaline lakes as well. High pH and salinity often coincide, because of how soda lakes develop. The resulting hypersaline and highly alkaline soda lakes are considered some of the most extreme aquatic environments on Earth.
In spite of their apparent inhospitability, soda lakes are often highly productiveecosystems, compared to their (pH-neutral) freshwater counterparts. Gross primary production (photosynthesis) rates above 10 g C m day (grams of carbon per square meter per day), over 16 times the global average for lakes and streams (0.6 g C m day), have been measured. This makes them the most productive aquatic environments on Earth. An important reason for the high productivity is the virtually unlimited availability of dissolved carbon dioxide.
Hypersaline lake in the context of List of bodies of water by salinity
This is a list of bodies of water by salinity that is limited to natural bodies of water that have a stable salinity above 0.05%, at or below which water is considered fresh.
Water salinity often varies by location and season, particularly with hypersaline lakes in arid areas, so the salinity figures in the table below should be interpreted as an approximate indicator.
Lake Eyre (/ɛər/AIR), officially known as Kati Thanda–Lake Eyre, is an endorheic lake in the east-central part of the Far North region of South Australia, some 700 km (435 mi) north of Adelaide. It is the largest ephemeral endorheic lake on the Australian continent, covering over 9,000 km (3,500 sq mi). The shallow lake is the depocentre of the vast endorheic Lake Eyre basin, and contains the lowest natural point in Australia, at approximately 15 m (49 ft) below sea level. The lake is most often empty, filling mostly when flooding occurs upstream in Channel Country, but almost always partially. On the rare occasions that it fills completely (only three times between 1860 and 2025), it is the largest lake in Australia, covering an area of up to 9,500 km (3,668 sq mi). When the lake is full, it has the same salinity as seawater, but becomes hypersaline as the lake dries up and the water evaporates. To the north of the lake is the Simpson Desert.
The lake was named in honour of Edward John Eyre, the first European to see it in 1840. It was officially renamed in December 2012 to include its AboriginalArabana name, Kati Thanda, in accordance with a policy of dual naming. The native title over most of the lake and surrounding region is held by the Arabana people, with the eastern portion allocated to the Dieri people.
