With the turning of the seasons, spring is showing its first colours. Green grass is emerging on the slopes of Piatra Craiuliu, and the white snowdrop is beginning to bloom in the Secular Forest of Sinca. The migratory pelicans are making their way to the Danube Delta and the brown bears are awakening from their hibernation in the Carpathian Mountains. Nature in Romania is truly a marvel to behold this time of the year.
Yet if you were to find yourself in Constanța county, nearby the Black Sea and close to the Bulgarian border, you may think otherwise as you stood on a desolate, homogeneous field, believing nature has eluded this seemingly barren landscape. The marvels of this land however, are extraordinary, and one remarkable feature that escapes the horizon has made a breakthrough in science and been labelled as one of the greatest discoveries of this epoch.
Jean-Francois descending the shaft 
Cristian entering the lower submerged passages
Underneath the empty hills, lies Movile Cave. A cave that has not only lay hidden from sight, but a cave that has been sealed and isolated from the surface for 5.5 million years. It is a cave that houses its very own endemic ecosystem. It is a chemoautotrophic ecosystem, meaning that it has phenomenally managed to thrive without solar energy. It was discovered in 1986, by geologist, speleologist, and former (and first) Editor-in-Chief of National Geographic Romania, Cristian Lascu.
The cave ceiling is sealed with a thick layer of clay above it, which is impermeable to water. When Lascu first visited, he could not find any stalactites or stalagmites, or any other sign of water coming from the surface.
“The surface environment carried traces of radioactivity linked to the Chernobyl disaster, where no such traces existed in either atmosphere, soil or water inside the cave.”
Dr. Florian Baciu, Response System Coordinator at International Atomic Energy Agency
Impermeable clay ceiling 
Asellus, aquatic isopod
The unique underground ecosystem supports a plethora of life. Biologists from the Romanian National Institute of Speleology in collaboration with NASA have identified 48 species, including 33 found nowhere else in the world. Counting a spider whose only nearby relative is found over 4000km away in the Canary Islands.
The primary objective was to find out where they got their food from, as the tests showed no food particles in the water. A study in 1996 discovered that the source of food derives from bacteria called “autotrophs” which form tissue-paper-like mats that cover the surface of the cave and water.
Rather than using photosynthesis, the use of light as an energy source, the Movile bacteria use a process known as chemosynthesis.
“They get the energy needed from chemical reactions: the key ones being the oxidation of sulphide and similar sulphur ions into sulphuric acid, or the oxidation of ammonium found in the groundwater to nitrate.”
Dr. Rich Boden, Associate Professor of Microbial Physiology and Taxonomy
These chemosynthetic bacteria help explain why the cave is so large as “Sulphuric acid actually erodes the limestone, which is gradually making the cave bigger,” says Boden. “The process releases carbon dioxide, which is why levels are so high.”
This particular process of chemosynthesis is the source of food for other heterotrophic bacteria and fungi, which in turn is consumed by small insects, pseudoscorpions, myriapods and other invertebrates (isopods, springtails, woodlice). These little critters are prey of the unique species of larger predators such as spiders, snails, shrimps, leeches centipedes and newly discovered waterscorpions.
All of which procured unique physiological traits due to the absence of light, displaying translucent, depigmented bodies whilst their near total deprival of vision is paired with particularly long antennae.
“Movile is the only cave whose ecosystem is known to be supported in this way, and the only such ecosystem on land.”
Dr. Rich Boden, Associate Professor of Microbial Physiology and Taxonomy
© Patrick Landmann
“It’s very likely that the bacteria have been there a lot longer than five million years, but that the insects became trapped there around that time… They could have simply fallen in and become trapped when the limestone cast dropped, sealing the cave until it was discovered again in 1986.”
J. Colin Murrell, Professor in Environmental Microbiology
Larry Lemke from NASA, has been working on a lifetime research mission on Mars, and compares the living conditions and ecosystem of the Movile cave to the Red Planet. He has suggested that there may have been life forms on Mars, 3.5 billion years ago, when it was warmer. The case-study of Movile cave has reignited the hope of finding incipient life forms in the underground of Mars, where volcanic thermal water sources are found.
For more information, publications and documentaries, please visit:
https://www.gesslab.org/movile-cave
http://www.bbc.com/earth/story/20150904-the-bizarre-beasts-living-in-romanias-poison-cave
https://science.sciencemag.org/content/272/5270/1953
Amazing article! Very interesting how Romanias nature does not seize to surprise!