The Merro Sink-Hole (Pozzo del Merro), which is situated in the vicinity of Rome, is the deepest flooded karstic cavity known in the world; a proper geological and natural monument, it goes down in the bowels of the earth for at least 400 metres.
The sinkhole reaches the Earth’s surface in a protected area (integral reserve) created on purpose to safeguard it and called “Macchia del Barco e Macchia di Gattaceca”.
Recently, the first part of the large scientific project called “Pozzo del Merro 2007 – MS Project” (organised by the Italian scuba magazine Mondo Sommerso and Provincia Di Roma – the authority that manages the reserve – to explore the well, concluded with an incredible free dive descent (never tried before!!!) in its completely dark waters, by Stefano Makula, the famous free-diving champion and 28 times holder of the world apnea record.
The MS Project was conceived to study the biocenosis (a group of interacting organisms that live in a particular habitat and form an ecological community), its abiotic structures (non-living – the abiotic factors of the environment include light, temperature, and atmospheric gases), and the relationships or dependencies that link things so that we know in an exhaustive way the many secrets contained in Merro well.
A team of physiologists, pathologists, hyperbaric doctors and psychologists from the University of Florence – Department of Medicine, AIPS – Sports Psychologist Italian Association, the University of ROME Tor Vergata, Motor Science Faculty, and Centro Iperbarico Romano, studied Stefano Makula’s reactions when he was exposed to the free-diving stress in such a claustrophobic environment, with a series of experiments and tests.
Scientists and researchers of three Italian Universities, led by one of the most important Italian zoologists and population genetic experts, Prof. Valerio Sbordoni (Director of Laboratorio di Ecologia Sperimentale e Acquacolatura, University of Rome, Tor Vergata), took samplings underwater in the sink-hole for about a month thus obtaining valuable answers on the conservation status of the Merro ecosystem:
“Our worry”, Professor Sbordoni explained, “was that an invasion by an alien tropical fern(Salvinia molesta), which occurred three years ago, could have compromised the peculiar biotic community of the well, which was unique in the world.”
Fortunately divers established that there is still a very rich presence of newts, frogs, and other invertebrates. In particular, a researcher, Dr. Roberto Palozzi, during an exacting dive, was able to sample a little crustacean (Anphipoda) at 73 metres, which is endemic in the Merro well: Niphargus cornicolanus. It demonstrates that the Pozzo del Merro ecosystem is alive at its great depth. The sink-hole still conceals a lot of scientific mysteries. Divers have discovered an aquatic American turtle (genus Trachemys) that gives a clue to how the tropical fern arrived in the well.
A fundamental support for the Merro exploration came from the participation of one of the greatest cave divers in history, the American Jim Bowden, who accepted the invitation of Mondo Sommerso to join the exploration team with enthusiasm; Bowden dove for two weeks in the well providing his technical skills and, above all, his great experience to compare the Merro’s structure with Zacaton, the famous Mexican Cenote, where he established a world depth record in 1994.
Besides zoology, botany, microbiology, hydrogeology, and archaeology the scientific project investigated neurology, pathology, diving physiology and psychology with continuous monitoring for six-months of all the divers who worked in Pozzo del Merro.
As said before, Stefano Makula accepted being a “guinea pig” for scientific studies and was the first person in the world to dive in apnea in a cave, going to 48 metres.
“Not one of my 28 world records” – was so exciting like the descent in Pozzo del Merro,” he said. “It’s an incredible place and to reach the surface of the water it is necessary to descend for 80 metres with ropes like an alpinist. Then you arrive at a green field and you have to imagine that under this vegetation there’s a hole, which goes down for at least 400 metres! But I felt my greatest emotion when I put my head under the water and I saw the dark, darker than I had ever seen. It’s very dangerous because you can’t lose your way back to the surface and I climbed the rocks underwater to go back up.”