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Movile Cave (Romanian: Peștera Movile) is a cave near Mangalia, Constanța County, Romania discovered in 1986 by Cristian Lascu during construction work a few kilometers from the Black Sea coast.

It is notable for its unique subterranean groundwater ecosystem abundant in hydrogen sulfide and carbon dioxide, but low 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. Due to its extreme environment, access to Movile Cave is strictly controlled, and a limited number of researchers have permission to study its conditions. Similar caves where life partly or fully depends on chemosynthesis have been found in Ein-Nur Cave and Ayalon Cave (Israel), Frasassi Caves (Italy), Melissotrypa Cave (Elassona municipality, Greece), Tashan Cave (Iran), caves in the Sharo-Argun Valley in the Caucasus Mountains, Lower Kane Cave and Cesspool Cave (Wyoming and Alleghany County, VA, USA), and Villa Luz Cave (Mexico).

Movile Cave is a network of paths in limestone that are approximately 200 metres (660 ft) long, with portions that are partially or fully submerged by hydrothermal waters. The air in the cave is extremely 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 100 times more carbon dioxide (2–3.5% CO2 in the cave atmosphere, versus 0.04% 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).

Movile Cave is classified as a karst cave that formed through weathering and dissolution of carbonate rocks in view of acidic groundwater over millennia.

Movile Cave supports a complex ecosystem built upon chemosynthetic bacteria. Similar chemosynthetic ecosystems have been found in Ayalon Cave and Villa Luz Cave.

The organisms within Movile Cave have gained unique adaptations in order to survive its extreme chemosynthetic environment.

Among the key species found in Movile Cave are leeches, troglobitic (species that only live in caves and have fully adapted to it) centipedes, and cave-adapted spiders.

The Movile Cave represents a distinct habitat that shelters a multidisciplinary community of microbial eukaryotes adapted to very specific low-oxygen, high-sulfide, and methane-saturated environments.

Movile Cave hosts a wide range of eukaryotic organisms such as fungi and protists, which are the key eukaryotic groups within microbial mats. Protists are mainly involved as decomposers and oxygen producers within the Movile cave. The most dominant eukaryotic supergroups in Movile cave include Ciliates (Alveolata), Stramenophiles (Bicosoecids) and Excavata (Jakobids).

Alveolata are abundant in the microbial mats and plankton as keystone grazers in Movile cave, regulating bacterial populations and promoting organic matter turnover.

Stramenophiles found in the Movile Cave were also very diverse, and clustered into three abundant groups—Bicosoecids, Labyrinthulids, and Chrysophytes.

90 species were found in the dry sections, including 51 from cave air, 42 from cave sediments, and 41 from various substrates such as dead invertebrates, corroded cave walls, and isopod feces.

Some organisms in Movile Cave, including some invertebrate species, are dependent on symbiotic associates with chemosynthetic microorganisms.

Two species of the groundwater amphipod genus Niphargus have been observed in Movile Cave. One specimen of the species Niphargus cf. stygius found in Movile Cave was observed in an ectosymbiotic relationship with sulfur-oxidizing Thiothrix bacteria, a genus of bacteria known to thrive in inverse sulfur-oxygen gradients, and have been observed in ectosymbiotic relationships with invertebrates in hydrothermal vent locations. These epibionts were discovered through genetic sequencing to be genetically different from the free-living Thiothrix found in microbial mats within Movile Cave, suggesting the epibionts have adapted to living on Niphargus cf. stygius.

The long-term isolation of Movile Cave has led to unique evolutionary adaptations of its microorganisms and eukaryotic communities.

Quick Facts

• Due to its extreme environment, access to Movile Cave is strictly controlled, and a limited number of researchers have permission to study its conditions.
• Similar chemosynthetic ecosystems have been found in Ayalon Cave and Villa Luz Cave.
• 90 species were found in the dry sections, including 51 from cave air, 42 from cave sediments, and 41 from various substrates such as dead invertebrates, corroded cave walls, and isopod feces.
• Movile Cave supports a complex ecosystem built upon chemosynthetic bacteria.
• Movile Cave is a network of paths in limestone that are approximately 200 metres (660 ft) long, with portions that are partially or fully submerged by hydrothermal waters.

Source material: Wikipedia - "Movile Cave". Adapted and summarized for DiscoverScroll. Original contributors are credited through the linked Wikipedia article. Read original on Wikipedia. CC BY-SA 4.0. Changes were made from the original.