Researchers have discovered dozens of life forms at great depths beneath the Antarctic ice sheet, with an unprecedented level of biodiversity for a complete environment devoid of sunlight.

At great depths beneath the Antarctic ice cap, researchers have discovered dozens of life forms in a small perimeter on the marine plateau – an unprecedented level of biodiversity for an environment completely deprived of sunlight, according to a material published Thursday by Live Science. quoted by Agerpres.

“If someone had asked me what I expected to see there at the beginning, I would have said something completely different and I would not have been right,” said David Barnes, a marine biologist with the British Arctic Survey, one of the co-authors of the study. published in the journal Current Biology.

At great depths under the Antarctic ice cap, protected from solar radiation, there may be life, but biologists believe that biodiversity would be reduced. Most ecosystems are based on photosynthetic organisms, such as planets or algae, and in the abysmal darkness there should not be enough food sources to support a wide variety of life forms.

Researchers Gerhard Kuhn and Raphael Gromig of the Alfred Wegener Institute used hot water to send a probe through 200 meters of ice under the Ekström ice floe in 2018. They were surprised by the samples of sand and silt they found. brought to the surface after the probe descended another 100 meters until it reached the marine plateau.

The ice sheets cover about 1.6 million square kilometers of ocean, and what is under the ice could be the least explored underwater habitat on Earth.

In such a dark and seemingly hostile environment, the team discovered numerous fragments of living organisms and sent the collected samples to David Barnes for analysis.

Under a microscope, biologists observed that fragments of the collected samples came from different creatures. David Barnes has identified 77 different species, far more than anyone would have expected to find. The British biologist admits that at one point he wondered if he was the victim of a prank. “We examined more fragments of organisms than would have been expected from a single marine plateau probe,” he said.

Many of the species identified belong to the class of bryozoans (small, marine or freshwater invertebrates, which live fixed to the bottom of the water or to objects in the water, forming muscle-like colonies), such as Melicerita obliqua or Paralaeospira sicula, among others. . “The discovery that life can be so abundant even in such extreme conditions is a great surprise and reminds us how unique and special Antarctic marine life is,” Barnes told Live Science.

The fact that there is a diverse ecosystem under the ice can be a surprise. Marine life, especially organisms that live in fixed colonies and feed by filtering the surrounding water, such as bryozoans, sponges and jellyfish, should theoretically be extremely rare under ice floes. These organisms feed on algae, which in turn need sunlight to live and are thought to be far too delicate to withstand temperatures of -2.2 degrees Celsius.

However, these invertebrates feed on microorganisms of the ciliate or dinoflagellate class, which are carried under the ice by ocean currents. “The surprise is that enough of these microorganisms get down there,” Barnes said.

Carbon dating of fragments of discovered organisms shows that such ecosystems are by no means recent. “Although they live 3 to 9 miles from the open ocean, under the ice, such an oasis of life could have had a continuous existence of 6,000 years,” said Gerhard Kuhn, coordinator of the team that extracted the sample from the ice. . The oldest remains discovered are about 5,800 years old, but biologists have so far dated only about 20 percent of the fragments discovered.

“It could be the most undisturbed habitat on Earth,” Barnes said of the space between the lower end of the ice sheet and the seabed. The lack of any external influence could explain the diversity of species in this ecosystem. Under the ice, these life forms are not exposed to storms and other dangers, the British biologist also explained.

Sursa photo: Pixabay / PiotrZakrzewski

 
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