Movile Cave

Coordinates: 43°49′32″N 28°33′38″E / 43.825694°N 28.560556°E / 43.825694; 28.560556 Movile Cave (Romanian: Peștera Movile) is a cave near Mangalia, Constanța County, Romania discovered by Cristian Lascu in 1986 a few kilometers from the Black Sea coast. It is notable for its unique groundwater ecosystem rich in hydrogen sulfide and carbon dioxide but very poor in oxygen. Life in the cave has been separated from the outside for the past 5.5 million years and it is based completely on chemosynthesis rather than photosynthesis.

The air in the cave is very different from the outer atmosphere. The level of oxygen is only a third to half of the concentration found in open air (7–10% O₂ in the cave atmosphere, compared to 21% O₂ in air), and about one hundred times more carbon dioxide (2–3.5% CO₂ in the cave atmosphere, versus 0.03% CO₂ in air). It also contains 1–2% methane (CH₄) and both the air and waters of the cave contain high concentrations of hydrogen sulfide (H₂S) and ammonia (NH₃).

Forty-eight species, among them leeches, spiders, water scorpions and other insects, were found inside the cave, of which 33 are endemic. The food chain is based on chemosynthesis in the form of methane- and sulfur-oxidising bacteria, which in turn release nutrients for fungi and other bacteria. This forms microbial mats on the cave walls and the surface of lakes and ponds which are grazed on by some of the animals. The grazers are then preyed on by predatory species.

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