Lake Matano also known as Matana, is a natural lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 in South Sulawesi

South Sulawesi

South Sulawesi is a province of Indonesia, located on the western southern peninsula of Sulawesi Island. The province is bordered by Central Sulawesi province to the north, South East Sulawesi province to the east and West Sulawesi province to the west...

, Indonesia

Indonesia

Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

. It is the deepest lake in Indonesia (ranked by maximum depth), and the 10th deepest lake in the world. It is located at 2°29′7"S 121°20′0"E.

Endemic Fish of Matano

Lake Matano is home to many species of endemic fish and other animals as well as many plants. The endemic fishes of Matano have been compared to that of the species swarms of the Rift Valley Lakes

Rift Valley lakes

The Rift Valley lakes are a group of lakes in the Great Rift Valley formed by the East African Rift which runs through the whole eastern side of the African continent from north to south...

 of Africa. While not as diverse, they are thought to have all arisen from a single ancestor species and diversified into numerous different species, which now fill many of the previously vacant ecological niches.

Environmental Concerns

Despite Lake Matano's remote location, it is the site of Pt. INCO, one of the largest nickel mines in the world, which carries out strip mining in the surrounding rainforest. although large areas are cleared for mining the company has a well regarded rehabilitation program and award-winning sediment control systems. The waters of Lake Matano are exceptionally clear, visibility is good, and many of the fish species are highly dependent on visual cues and colour perception for their mating behaviour. If the sediment washing into the lake continues to increase, the likelihood is that many of these endemic species will be lost.

Scientific interest

Below the top layer of oxygenated water, Lake Matano's depths are anoxic, free of sulfates, and rich in iron. These conditions make Lake Matano an analog for Earth's oceans during the Archean

Archean

The Archean , also spelled Archeozoic or Archæozoic) is a geologic eon before the Paleoproterozoic Era of the Proterozoic Eon, before 2.5 Ga ago. Instead of being based on stratigraphy, this date is defined chronometrically...

 Eon, which is useful for studying relationships between anoxygenic phototroph

Phototroph

Phototrophs are the organisms that carry out photosynthesis to acquire energy. They use the energy from sunlight to convert carbon dioxide and water into organic material to be utilized in cellular functions such as biosynthesis and respiration.Most phototrophs are autotrophs, also known as...

s and banded iron formation

Banded iron formation

Banded iron formations are distinctive units of sedimentary rock that are almost always of Precambrian age. A typical BIF consists of repeated, thin layers of iron oxides, either magnetite or hematite , alternating with bands of iron-poor shale and chert...

s. The lake contains a population of green sulfur bacteria

Green sulfur bacteria

The green sulfur bacteria are a family of obligately anaerobic photoautotrophic bacteria. Most closely related to the distant Bacteroidetes, they are accordingly assigned their own phylum....

 that conducts photosynthesis with bacteriochlorophyll

Bacteriochlorophyll

Bacteriochlorophylls are photosynthetic pigments that occur in various phototrophic bacteria. They were discovered by Von Neil in 1932 . They are related to chlorophylls, which are the primary pigments in plants, algae, and cyanobacteria. Groups that contain bacteriochlorophyll conduct...

e.