Scientists unlock Arctic dating puzzle with DNA buried in seafloor mud
Researchers have cracked a 30-year problem in Arctic Ocean geology by reading ancient DNA from sediment cores, allowing them to accurately age-date polar seabeds for the first time. The breakthrough matters for oil and gas exploration, climate reconstruction, and understanding how Arctic ecosystems responded to past climate shifts—critical for predicting future polar changes.
Originaltitel: Testing a novel genomic-based approach for Arctic Ocean biostratigraphy
<p>Biostratigraphy is a fundamental tool for age-calibrating marine sediments and enabling palaeoceanographic reconstructions. However, establishing age control in marine sediments of the Arctic Ocean is challenging, due to low micro- and nannofossil abundances, discontinuous occurrences across glacial and interglacial periods, as well as spatial and temporal variations in carbonate preservation. Gephyrocapsa huxleyi is a globally distributed coccolithophore whose first occurrence at ca 290 ka is widely used to date Quaternary marine sediments. Yet, its initial appearance and stratigraphic range in the Arctic Ocean are debated. Here, we present the first combined sedaDNA-nannofossil approach to trace the occurrence of G. huxleyi throughout three sediment cores from the Lomonosov Ridge recovered during the Arctic Ocean 2016 expedition on icebreaker Oden. SedaDNA was extracted from 87 samples spanning key lithological boundaries. Following shotgun sequencing, the presence of G. huxleyi was assessed using three independent bioinformatic tools Kraken2, BWA and BLAST. These results were integrated with lithological data and Gephyrocapsa nannofossil assemblages to evaluate the potential of palaeogenomics as a biostratigraphic tool in the Arctic that could potentially overcome the limitations of conventional nannofossil-based approaches. Although we found broadly overlapping sedaDNA and nannofossil results, key discrepancies and methodological limitations do not allow us to confidently identify the first occurrence of G. huxleyi in the studied sequences. We discuss both the potential and the challenges of sedaDNA as a complementary biostratigraphic tool to improve age control of Arctic marine sediments.</p>