Dormant algae revived after 7,000 years beneath the Baltic Sea, researchers say

Yahoo

01-04-2025

Researchers have successfully revived algae that remained dormant within sediment at the bottom of the Baltic Sea for more than 7,000 years.
The tiny diatom cells have regained full biological activity despite thousands of years beneath the seafloor without light or oxygen, according to the paper, published in the ISME Journal.
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The specimen was extracted from sediment cores taken from a spot nearly 800 feet deep in the Eastern Gotland Deep in 2021, according to the paper.
Many organisms, from bacteria to plankton to mammals, can go into "sleep mode," or dormancy, in order to survive periods of unfavorable environmental conditions -- switching to a state of reduced metabolic activity, according to the researchers. The dormancy often provides robust protective structures and internally stored energy reserves for the organisms.
For phytoplankton, the organisms sink to the bottom of the ocean during dormancy, and they are eventually covered by sediment over time and preserved by the lack of oxygen.
In a breakthrough experiment, researchers from the Leibniz Institute for Baltic Sea Research Warnemünde were able to practice "'resurrection ecology" to return the plankton to full viability under favorable conditions, according to Sarah Bolius, phytoplankton expert at the institute and lead author of the study. The evolutionary biology technique involves reviving dormant organisms from lake sediments to study animals as they existed at the time they were buried in the sediment.
The visible algae was able to be awakened from dormancy from nine sediment samples under favorable nutrient and light conditions, the researchers said.
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Despite remaining dormant for several thousands of years, the phytoplankton specimens did not lose any of their "fitness" or biological performance ability, Bolius said in a statement. Even the oldest algae isolates can still actively produce oxygen, a measurement of photosynthetic performance found.
Successful resurrections of dormant organisms have rarely been documented, according to the researchers.
"This means that it is now possible to conduct 'time-jump experiments' into various stages of Baltic Sea development in the lab," Bolius said.
Dormant stages of phytoplankton extracted from the Baltic Sea can be clearly assigned to specific periods due to the "clear stratification" of the Baltic Sea sediment, Bolius said in a statement.
The diatom species Skeletonema marinoi was the only phytoplankton species revived from the samples. The species is common in the Baltic Sea and typically occurs during the spring bloom, according to the researchers.
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The researchers are hoping to use the findings to discover more about the environment at the time. They will compare the organisms to modern phytoplankton and also analyze other sediment components to draw conclusions about past salinity, oxygen and temperature conditions, according to the paper. The research has also shown that they can directly trace genetic changes over many millennia by analyzing living cells, rather than fossils or traces of DNA.
"Such deposits are like a time capsule containing valuable information about past ecosystems and the inhabiting biological communities, their population development and genetic changes," Bolius said.
Dormant algae revived after 7,000 years beneath the Baltic Sea, researchers say originally appeared on abcnews.go.com