The secret of the sponge gardens

Thriving sponge gardens have been discovered in the depths of the Mediterranean off the coast of Israel. How are they related to the development of a cure for cancer, and what is being done so that they are not harmed by the gas and oil drilling?

By Racheli Vox, Angle, Science and Environment News Agency

Rich and diverse sponge gardens were recently discovered at a depth of one hundred meters under the waters of the Israeli Mediterranean Sea. Right here, close to home, there are more than 80 different species of sponges, most of which are found in Israel only at this depth, and around them swarms a whole world of fish and other marine animals, for which the sponges are the basis of their existence. However, this world, which science has only recently begun to recognize, may be in existential danger already in the coming years, due to the plans for gas and oil drilling off the coast of the country.

Potential for drug development

In a study, conducted in collaboration with the Department of Zoology at Tel Aviv University and the Nature and Parks Authority and recently presented inThe annual science and environment conference For the first time, these sponges, which live at a depth of one hundred meters below sea level, were examined - a place where sunlight almost never penetrates. The work is done from the MedEx research ship belonging to the "Equasion" association.

The sponge is one of the earliest multicellular animals. This is a set of very diverse creatures: There are over 8,000 species of sponges, which are very different from each other in color, shape and size. The different species live in diverse environments around the globe, from the poles to the equatorial region.

Throughout history, man has made and still makes use of sponges for diverse purposes. various drugs, such as drugs currently used to treat cancer, contain chemical compounds derived from certain species of sponges. In addition, the sponges are very important to the ecosystem, and create habitats for other creatures on the seabed, which would not survive without them.

Sponges are sedentary animals: they stick to the seabed and do not move from it. Thus, the function of the sponges in the sponge gardens is similar to that of corals in the coral reefs - in that they create the habitat. The sponges provide a substrate for settlement, hiding from predators and suitable places for reproduction, and are important for the survival of small animals, which feed on the sponges themselves, as well as larger predators. Despite all this, the sponges in the area of ​​Israel's coasts, and especially in the depths of the sea, have hardly been studied over the years.

Sponges that were unknown to science

In the study, which was conducted as part of Tal Iden's doctoral thesis in the laboratory of Prof. Micha Ilan from Tel Aviv University, three sites were examined: Herzliya, Atlit and Rosh Carmel, and they discovered diverse and unusually rich sponge gardens for the Israeli coast. Of the more than 80 species observed at the sites, the researchers were able to collect and describe 33 sponge species, using an unmanned underwater vehicle with a robotic arm and a high-resolution camera, which was purchased with the support of the Ministry of Science. Only eight of the species found are also known from the shallow waters in Israel, and some of the species found lived in the shallow waters in the past but no longer exist in them nowadays. Some of the species that are common at depth also exist in other areas of the Mediterranean and are in danger of extinction there, and it is possible that two of the individuals collected are completely new to science and have never been recorded.

The three sites are also very different from each other in terms of the species of sponges found in them, a fact that emphasizes the importance of preserving each and every one of them, and also raises the possibility that a large and unknown variety of sponges is also found in sites that have not yet been explored. Also, the researchers believe that substances originating from the unique species of sponges found in the depths may directly benefit humans thanks to the medicinal potential that may lie in them.

Iden explains why many of the peon species have disappeared from the shallow waters off the coast of Israel, and are now only found in the depths. "The temperature in the shallow water currently reaches 30 degrees, and we are not even at the height of summer," she says. "Many marine animals cannot tolerate such a high temperature, certainly not for a long time. Once upon a time, the peak temperature lasted for two weeks at the end of August, whereas today the peak temperature reaches 31 degrees and lasts for a much longer period of about a month and a half."

The warming Mediterranean Sea is not the only reason that the shallow water is a less comfortable living environment for some sponges. "In our shallow waters there is a lot of algae, and it is very difficult for sponges to compete with them. Beyond that, water pollution probably also has some effect, which is why there is also a decrease in the richness of species in shallow waters in other areas of the Mediterranean."

Declare marine nature reserves

Despite the more comfortable living conditions enjoyed by those immersed in the deep, their future is in jeopardy. Beyond the risk due to increased fishing, today the sponges are also threatened by the gas and oil drilling carried out in the Mediterranean Sea. But thanks to the initial results of the research, the rocky areas at a depth of one hundred meters were recognized as areas with a high level of sensitivity In the environmental strategic survey for the search and production of oil and natural gas at sea (SS). "This work is very helpful in setting policy," explains Dr. Ruthie Yehal, a marine ecologist at the Nature and Parks Authority who is a partner in the research, "and this research is an excellent example of science-based nature conservation - data and findings allow us to promote marine nature conservation."

Indeed, Dr. Eran Brockowitz, senior oil environment center at the Ministry of Energy, explains that "following the SAS, the Ministry of Energy released for gas and oil exploration only areas that are in Israel's economic waters, far beyond the depth of the sponge gardens. In addition, when infrastructure such as a pipeline needs to be moved or a rig erected, we require keeping a distance from sensitive habitats, including the newly discovered sponge gardens. That is, in practice the sponge gardens will not be harmed by the gas and oil industry."

Despite the optimistic things, Eden emphasizes that this protection is not enough. "The investigated sites are not defined as reserves or protected areas. Until we give official approval and call the place a nature reserve, we have no unequivocal guarantee that the sponge sites will not be damaged. These sites should be recognized as marine nature reserves so that they are not harmed."