Animal habitats have been placed deep in the sea off the coast of Israel. They reveal unique living conditions that have been almost unexplored.
A little over three years ago, a team of Israeli researchers and divers entered the depths of the sea off the coast of central Israel, in an area called the "Palmahim Disturbance." Using an underwater robot, they attached six "settlement boards" to the seabed, hundreds of meters deep. A few weeks ago, they returned to the same place to collect the boards and the animals that had accumulated on them. The first findings already indicate the unique living conditions at the intriguing site.
Thanks to technology
The "Palmahim Trench", or by its professional name the "Palmahim Trench", is a marine area 15–65 km off the coast of Israel that extends between Tel Aviv and the Palmahim Coast. The area is characterized by a landslide with a unique geological structure that begins at a depth of 400 meters and reaches more than 1,200 meters below sea level. The area was first discovered in the late 70s, but until 2010 it was almost unexplored due to the lack of suitable technological tools. In September 2022, it was declared "Palmachim disorder"As a protected marine area."
Due to the great depth and complete absence of sunlight, unique and sensitive underwater ecosystems have developed in the "Palmahim Disturbance." They are different from ecosystems on Earth that rely on sunlight as a source of energy. Over the years, deep-sea coral reefs have been found there, among other things, that stretch over several kilometers, most of which have been designated as endangered species, alongside a rich and diverse habitat that includes crabs, sharks, sea urchins, and sea anemones. Later, cold gas vents, abundant shark spawning areas, brine lakes, and more were also discovered there.
Some of the animals that have managed to survive and establish themselves in the area develop and feed by utilizing the main source of energy available there – methane gas springs and other compounds that bubble up from the earth's interior. "These are very unique living conditions. Thanks to the greenhouse gases, such as methane, that are emitted from the seabed, special and fascinating ecosystems are created that serve the animals," explains Dr. Maxim Rubin-Blum, a senior researcher at the Israel Institute of Marine and Lake Research (IIL) and a senior lecturer at the School of Marine Sciences at the University of Haifa, who is leading the project together with Prof. Yitzhak Makowsky from the School of Marine Sciences at the University of Haifa. "First of all, our goal is to monitor the environment, follow the [ecological] systems and identify if there are any changes. To do this, we use tools that can scan the area well and collect samples," explains Rubin-Blum.
Deep sea conservation
The project is part of a larger European project called "STRAIGHTEN"For Deep Sea Habitat Restoration, which focuses on questions of how and if it is possible to preserve, restore, and rehabilitate these unique ecosystems. "The entire project deals with the restoration of damaged ecosystems in the deep sea, mainly in populations of deep-sea corals that are considered very sensitive systems," says Rubin-Blum.
The panels placed in the deep sea are called ARMS (Autonomous Reef Monitoring Systems). These are installations made of panels placed one on top of the other to monitor the settlement of marine organisms. This is the first time in the world that such panels have been placed In maritime territory So deep. "These boards are not optimal, so they are constantly being updated and new materials are added, because animals don't like to settle on a smooth substrate," he explains. In parallel with the recent collection of facilities, the researchers installed new, more sophisticated and rougher facilities, which are supposed to improve settlement conditions and allow more animals to settle there better. "The goal is to simulate the substrate as much as possible to a natural environment," says Rubin-Blum.
"We saw on the plates that we had taken out special creatures like sea urchins and very rare bacteria. Seeing them in pictures and video from the robot is amazing. I remember when I started getting into the field and saw the film series 'The Blue Planet', with David Attenborough, I said to myself that I had to do something similar, and here we came up with simply amazing results and pictures," he says.
"We are working in two ways to better understand what is happening there: through morphology – a visual description of the creatures, and through molecular identification of DNA [samples]. The goal is to look at the diversity of species that exist, and to understand the rate of colonization," explains Prof. Tamar Guy-Haim of Beersheba University and director of the Marine Biology Department at the Israel Institute of Technology. "The intention was to place the panels and return after a year, but that was delayed, partly because of the war. We returned after three years, and this is actually the first time we have an estimate of the rate of colonization at such depths and in such a habitat," she says. "We found that the rate of colonization is very low. In other words, after three years, we saw very little colonization, mainly of sea anemones." According to her, the slow rate of colonization mainly indicates the sensitivity of the entire area.
The menu at the bottom of the sea
"The slow development stems from the unique conditions of the area, and probably because the population there consists of many 'omnivorous' animals such as small snails and sea urchins that come there in droves and destroy everything growing on the plates. We hope that in the new plates we will see an improvement in this regard," explains Rubin-Blum.
Another interesting discovery highlights the uniqueness of the habitat. "We attached stainless steel handles to the surfaces so that the robot could hold them and attach the installations to the bottom. When we removed them, we saw that all the stainless steel had turned into huge rust blocks as a result of an electric current created by a unique chemical composition in the system. This was not planned, but it is proof of the great power that resides in the gas vents," said Rubin-Blum.
Even though the Palmachim Disturbance is located deep in the sea, it is still vulnerable to threats. The main risks to the area are: Drilling and production of gas and oil and fuel spills. The corals that live in these areas are known to be sensitive to contamination, and even a small spill could cause significant damage. So far, no physical damage has been detected in the area, but according to Rubin-Blum, significant amounts of trash have already been found there. and plastic.
"The gas springs create pits of various sizes in the area, ranging in diameter from a few meters to tens of meters, and the garbage that reaches the area tends to accumulate in these pits. When there is a gas spring pit, we usually find more garbage around, and it's very sad to see that. On one of the recent dives, we collected a bag of garbage from the bottom with the robot. We also brought it into the laboratory to understand the processes that happen to plastic in the deep sea," he explains, adding that they are awaiting the results. As for the slow rate of settlement of the animals in the experiment, Guy-Haim says that beyond disappointment, "it teaches us the great importance of conservation in these areas. Because the system develops very slowly, so in the event of damage to it, the rate of recovery will be very slow," she concludes.
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