Researchers recover sediment cores from a depth of 240 meters in the Baltic Sea with ancient algae some of which, while still alive, had been inactive for 7,000 years.
Tiny The filamentous algae Skeletonema marinoi remained inactive for a long time, deprived of light and oxygen. They did not grow and did not conduct photosynthesis The oldest of them is estimated to be 7 thousand years oldNevertheless, the algae fully recovered their viability under the favorable conditions created by the scientists.
The sediment cores were recovered by the researchers of the Elisabeth Mann Borgese expedition from the bottom the East Holland Trough, a part of the Baltic Sea that is almost completely devoid of oxygen due to poor circulation and rapid decomposition of organic matter. Due to the lack of oxygen, algae cells have been in an inactive state for thousands of years, not decomposing
In intact sediment layers scientists have identified spores microscopic diatom Skeletonema marinoi, which blooms every spring in coastal waters. The scientists brought the inactive algae cells back to life in the laboratory. The youngest group had been inactive for only 3 years. The oldest — had been in a state of «hibernation» for many millennia.
According to Sarah Bolius, a scientist at the Leibniz Institute for Baltic Sea Research, the algae returned to an active state not only survived, but also have not lost any biological functions. They began to grow, divide, and conduct photosynthesis, just like their modern descendants.
The algae also helped scientists to further develop a technology called «resurrection ecology», which involves growing creatures that existed in the past in the laboratory using biomaterial obtained from water bodies. In controlled laboratory conditions, at low temperatures, in low light and in the stirred water of the Baltic Sea, scientists brought 9 groups of algae back to life Skeletonema marinoi.
As soon as the algae were exposed to oxygen and light, they began to grow. They formed chains, carried out photosynthesis, and reproduced just like their modern counterparts. Under the microscope, they looked almost exactly like modern representatives of their species.
«The fact that we have been able to successfully reactivate such old algae from dormancy is an important first step in the further development of a tool for «resurrection ecology» in the Baltic Sea. This means that it is now possible to conduct «time-jump experiments» at different stages of the Baltic Sea’s development in the laboratory», — explains Sarah Bolius.
This state of anabiosis is typical for many organisms and seeds of some plants under unfavorable conditions. Previously, scientists had managed to bring back to life mostly ancient terrestrial creatures. The oldest organism that survived in water and was resuscitated was 700 years old, and it belonged to freshwater crustaceans.
«As for creatures that live in water, the oldest reference to a revived and growing species is to the crustacean Daphnia pulicaria from a 700-year-old sediment layer of South Center Lake in Minnesota Viable cells that sprouted from dormant cells of diatoms (spores) and cyanobacteria (akinetes) were found in 6600-year-old oxygen-free sediments of the Baltic Sea (Landsort Trough) and almost 2000-year-old lake sediments in France, respectively», — the researchers emphasize.
Although scientists still do not fully understand how such survival mechanisms work, there is evidence that spores Skeletonema marinoi are not in a state of absolute inactivity. Studies show that they are able to assimilate nitrogen and other organic compounds even in the absence of sunlight and oxygen.
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