An international team of scientists has found the world’s oldest marine DNA in the Scotia Sea, north of Antarctica. It is a million years old and has been found in Antarctic sediments.
Antarctica is one of the most vulnerable regions to global warming on Earth and this finding could shed light on what lived in the ocean 1 million years ago and what the responses of ocean ecosystems to climate change would be in the future.
Priceless Organic Fragments
Technically known as sedaDNA , ancient sedimentary DNA (which can be found both in terrestrial caves and subarctic permafrost and elsewhere), these fragments of organic material were found beneath the floor of the Scotia Sea north of Antarctica by a team of researchers. international schools run by the University of Tasmania in Australia. The sediments were initially acquired during the IODP Expedition 382 “Iceberg Alley and Subantarctic Ice and Ocean Dynamics” in 2019 and have undergone a long process of analysis to verify that the DNA is not contaminated and is authentic, such as the investigation of characteristic damage patterns. related to age in the recovered DNA fragments.
“This comprises by far the oldest authenticated marine silk DNA to date,” explained Linda Armbrecht, lead researcher at the University of Tasmania.
This DNA is highly valuable as, thanks to the low temperatures, low oxygen level and lack of ultraviolet radiation, polar marine environments such as the Scotia Sea are fantastic places for DNA of this type to remain intact, waiting for an investigation team to find it, as in this case.
Among the organisms detected in the fragments were diatoms, or single-celled organisms, whose DNA was detected 540,000 years ago.
The researchers were able to link diatom abundance to warmer periods , the last of which in the Scotia Sea was about 14,500 years ago, when a shift in the Scotia Sea food web occurred. That led to an increase in the general activity of marine life throughout the Antarctic region.
“This is an interesting and important change that is associated with a rapid and global rise in sea levels and massive ice loss in Antarctica due to natural warming,” said geologist Michael Weber of the University of Bonn in Germany. and co-author of the work published in the journal Nature Communications.
The study shows that marine silkDNA investigations can span hundreds of thousands of years, paving the way to investigate alterations in the entire marine ecosystem and variations in paleoproductivity during numerous ice age cycles.
Understanding more about past climate changes and how the ocean ecosystem responded means we can get more accurate models and predictions about what might happen over time around the South Pole.
Referencia: Armbrecht, L., Weber, M.E., Raymo, M.E. et al. Ancient marine sediment DNA reveals diatom transition in Antarctica. Nature Communications 13, 5787 (2022). https://doi.org/10.1038/s41467-022-33494-4
