Worm snails used to restore damaged reefs with a chalky substance.
By Zafrir Rinat | May 31, 2015

It’s one of nature’s nonstop species of construction workers. Its scientific name is Dendropoma petraeum, and it’s a kind of small sea snail – known as the worm snail – that excretes a chalky substance through which it builds reefs facing Israel’s shores. This construction worker, however, is in big trouble and facing the threat of extinction. Now, scientists and other experts are figuring out how to come to its rescue, or finding an engineering solution that might save the reefs.

The Israeli Society of Ecology and Environmental Sciences (ISEES) will be convening a team of experts today in an effort to develop an action plan to deal with the threat the worm snail is facing. It is simply disappearing from many areas off the country’s coast, and in the process endangering the reefs that the snails build on – and where they and other creatures find shelter and a habitat.

“We don’t exactly know the reasons why it is disappearing,” said Gil Rilov of the Israel Oceanographic and Limnological Research Institute. “It’s possible that it’s connected to climate changes taking place in the Mediterranean.”

The type of reefs involved, called abrasion platforms, are found almost only in the Mediterranean, adjacent to about a tenth of Israel’s coastline. The reefs are home to a large number of species of fish, crabs and shellfish, and are reinforced by the secretions of the worm snails, which build their own chalky structures on the natural rock formations.

When the forces of nature have damaged or eroded them, the worm snail has managed to restore them, so the disappearance of the snail threatens the chalky reinforcement of the reefs that the snails provide.

The projected rise in sea levels due to climate change is set to exacerbate the problem, because it will cover the reefs completely with water, meaning the reefs will no longer be visible above the waterline.

The team of experts convening today will try to explore a number of approaches to the problem. “Preservation of the reefs themselves will not be sufficient, because the snail has almost disappeared,” said Eran Brokovich, the scientific director of ISEES. “We will try to examine the option of biological aid based on breeding the snails and returning them to nature. There are already studies being carried out in this direction.”

In addition, an engineering project will be considered that would create artificial abrasion platforms or reinforce platforms that are at risk due to the halt to the secretions from the snails. Such an option might be possible using special concrete made with environmentally friendly components. Such concrete has already been put to use in breakwaters. The advantage of concrete is that it can also provide a habitat for sea creatures and could replace natural reefs.

The panel is expected to develop a plan that will include recommendations on how to deal with the worm snails. In an effort to ensure that the recommendations influence decision makers, the committee includes representatives from the Environmental Protection Ministry and the Israel Nature and Parks Authority.

At a later stage, there will be a need to obtain the approval of a number of government entities in carrying out such a plan, which in its initial stage will include a trial approach on one stretch of shoreline.

After the results of that experiment are known, it will be possible to determine whether the major vacuum that this little snail has left can be filled.