One year later, 'Noah's Ark' cave is no longer a safe haven

Last update - 11:41 19/07/2007
By Ofri Ilani
http://www.haaretz.com/hasen/spages/883837.html

When researchers first entered the Ayalon Cave which was discovered in March 2006 near Ramle, they were surprised to find a species of eyeless troglobite, or blind scorpion, that orients itself through a motion sensor organ located on its abdomen.

"This species completely lost its eyesight, which necessitates the conclusion that it existed in the dark for a very long period," says zoologist Gershom Levy of The Hebrew University.

It soon emerged that the blind scorpion is not only a species previously unknown to science, but also the sole known representative of a previously unknown family of the scorpion order,- a fairly rare discovery.

"The presence of scorpions in this subterranean space attests, perhaps for the first time, to the isolated existence, beneath our world, of a fabric of life of a relatively high level of complexity," Levy explains.

The new scorpion was given the scientific name Akrav israchanani, named for its discoverers, Israel Naaman and Dr. Hanan Dimentman.

Unfortunately, all 10 or so blind scorpions found in the cave had been dead for several years, and only their outer shells remain. The last to die apparently did so in the early 1990s. This unique species, which had found refuge in the cave and survived there for millions of years, recently became extinct, for some unknown reason.

According to Naaman, - one of the first three people to enter the cave, intensive pumping of groundwater in recent decades led to a drop of some 12 meters in the water level, thereby shrinking the flooded areas.

"Out of a presumed 4,000 square meters of flooded area in the past, only 400 or so remains today," he explains. "I imagine the food supply in the cave shrank, and the scorpions could not longer exist."

The Ayalon Cave, Israel's third-largest, was discovered when a bulldozer working in a quarry operated by cement manufacturer Nesher Industries accidentally broke through an opening into the subterranean space.

Naaman recently finished mapping the 2,700 meter-long cave, which has several split-levels and several large halls. It is closed to the public, and entry is only through the small opening created by the bulldozer, which is now blocked by a door. The limited team of researchers permitted into the cave have to crawl and use ladders and ropes.

Aside from the uniqueness of the cave itself, the discovery's importance lies in the exposure of a unique ecosystem of arthropods residing there. In addition to the blind scorpion, another seven species of crustaceans and springtails (a species primitive insect) were discovered, some new to science.

As the research progresses, it is becoming increasingly clear that the cave is a sort of "Noah's Ark" that provided refuge for various invertebrates, while the rest of the creatures in their vicinity were wiped out by geological changes and catastrophes that occured over millions of years. Thus, the array of creatures in Ayalon Cave constitute a sort of bio-history of our region over the past hundreds of millions of years.

But while studying the new species, the researchers face the challenge of protecting them from outside influences, which threaten to radically alter the cave's unique conditions. For millions of years that ecosystem was completely isolated, the energy source for the food chain in the cave being sulfur, which percolated up from the depths of the earth and was melted by groundwater. The sulfur compounds are consumed by insects, which then produce organic matter. This matter provides the basis for the entire ecosystem, thus enabling it to survive without sunlight.