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Scientists warn that flooding cave will ruin unique 5-million-year-old ecosystem

Blind, colorless arthropods make their home in Ayalon Cave in central Israel, thriving in dark, oxygen-free environment, fed by sulfurous water rising from deep in the earth

Sue Surkes is The Times of Israel's environment reporter.

The subterranean lake in the Ayalon Cave near Ramle, in central Israel. (Israel Ne'eman)
The subterranean lake in the Ayalon Cave near Ramle, in central Israel. (Israel Ne'eman)

An underground cave cut off from the world for five million years and inhabited by strange and unique creatures that have adapted to sulfurous waters and complete darkness is being threatened by a plan to use the quarry in which it is located as a receptacle for seasonal floodwaters from the Ayalon River basin in central Israel.

Monday is the last day on which public objections can be submitted.

The National Infrastructure Committee and the Water Authority are looking for a place to which surface runoff water can be directed in the winter. This is in connection with plans for an additional rail line in the area that would require narrowing a section of the Ayalon River.

The quarry, near the city of Ramle, is owned by the Nesher cement factory.

Scientists from the fields of biodiversity, evolution, the beginnings of life, and hydrology are fiercely opposed to using the quarry, and say that planning committee members have not been told about the ecological implications of flooding it.

The Israel Nature and Parks Authority is also against the idea and has announced that it wants to turn the cave — only accessible to researchers to protect it — into an official nature reserve.

Originally hidden 100 meters (109 yards) below the surface, the cave was exposed when a bulldozer hit one of the tunnels in 2006. It includes 2.7 kilometers (1.67 miles) of narrow tunnels and a subterranean lake, today just a few meters below the surface. The lake is fed by the region’s aquifer and in a good year, can swell to hundreds of cubic meters of water. While the cave is made of common limestone, the water is warm, saline and contains hydrogen sulfide. Known as the Ayalon anomaly, the water comes up from deep in the belly of the earth.

Digging has been completed in that part of the quarry, leaving the cave enclosed beneath a small hill.

Blind scorpion. (Amos Frumkin)

Over the past 15 years, scientists have discovered eight species of arthropod (invertebrate animals with an exoskeleton), some terrestrial and some aquatic. All are found only in this cave and were previously unknown to science. All are blind and colorless, having no need for eyes or color in the dark. The blind cave prawn, the largest species discovered, has known relatives from other underground caves in Italy, Libya and in the vicinity of the Sea of Galilee. One theory is that the caves in all three places were refuges for creatures during a period some five million years ago when the Mediterranean Sea was drying up.

An eyeless scorpion has been categorized into a new zoological family of its own. Its closest known relatives are from Central America.

Without the sun, photosynthesis — which creates the foundation for the foodwebs of most living creatures — cannot take place.

Rappelling down into the Ayalon Cave. (Israel Cave Research Center)

In the cave, the foodweb is based on microorganisms that perform chemosynthesis, breaking down hydrogen sulfides in the groundwater.

Fewer than 10 similar underground ecosystems are known in the world, but each one is markedly different from the other.

Prof. Amos Frumkin, who heads the Israel Cave Research Center at the Hebrew University’s Institute of Earth Sciences in Jerusalem, told The Times of Israel that “Surface runoff water is completely different from the groundwater that serves as the basis of life in the cave, and entry of the former, in quantities three orders of magnitude greater than the latter, would be certain to destroy this unique ecosystem.”

He noted that the plans contain alternative sites that could be used for the floodwaters.

“The ecosystem in the Ayalon Cave is unique in the world,” wrote Ariel Chipman, an associate professor at the university’s Department of Ecology, Evolution and Behavior, in his objection. Chipman studies the evolution and adaptation to their environment of arthropods. (These include include lobsters, crabs, spiders, mites, insects, centipedes, and millipedes.)

Blind cave prawn. (Sasson Tiran)

“No other ancient system is known which is so exclusively concentrated on a foodweb disconnected from the [earth’s] surface and sunlight,”  he said.

Along with local organizations such as Adam Teva V’Din and several international bodies, the Israel Nature and Parks Authority is opposing the plan. It wants the cave recognized as a nature reserve.

“The Ayalon cave is a unique phenomenon on a global scale,” it said in a statement. “The cave was formed and continues to form due to specific conditions of groundwater. The entire ecosystem relies on primary sulfur-assisted production under oxygen-free conditions. Therefore, after a professional examination, the Nature and Parks Authority has decided to promote declaration of the cave as a nature reserve.”

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