Towards a marine genetic view of deep-time Greenland DeepGreen



The field of sedimentary ancient DNA (sedaDNA), which studies ancient genetic signals preserved in sediments, allows us to reveal ecosystem-wide responses to past environmental changes beyond what has so far been possible with standard environmental proxies. Such insights are particularly important for the Arctic, where warming is happening at a rate four times faster than the global average and where important climate tipping points are of global societal concern (e.g. Greenland Ice Sheet collapse, sea ice decline). The potential of using sedaDNA to reveal marine ecosystem-wide responses to climate throughout multiple glacial-interglacial cycles is enormous, and there is a large interest in utilizing the full potential of sedaDNA to improve ecosystem modelling and achieve a sustainable development of the ocean. But this requires that we can retrieve and explore deep-time marine DNA archives. So far, sedaDNA recovered from ocean sediments in the Arctic region has not reached beyond ~0.1 million years, yet the oldest authenticated sedaDNA has recently been reported from Greenland (~2 million years). Our project aims to answer the following questions: How long can DNA be preserved in Arctic marine sediments? How far back in time can we use DNA to uncover interactions between climate, the ocean, and the biosphere? And how have arctic marine ecosystems reacted to past climate and ice shelf dynamics? To answer them, we joined the International Ocean Discovery Program (IODP) Expedition 400 to NW Greenland and recovered a continuous ~0.9-million-year record and additional samples estimated to be >2-4 million years old. The mineralogic composition is a key predictor of DNA retention and preservation in sediments. By identifying the mineral composition of our samples using quantitative X-ray diffraction patterns, our team, composed of members from GEUS, Globe Institute and IGN, will analyze the mineral composition of the samples, the preservation state of the DNA, and optimize DNA extraction protocols that are currently known to release only a fraction of the preserved DNA. Furthermore, we will apply metagenomic shotgun sequencing – a method to sequence and represent the full organismic complexity of the samples. Accompanied by reconstructions of paleoproductivity (biogenic silica, microfossils) and Greenland weathering, the genetic composition of the samples will be explored to reveal information about ancient marine ecosystems of NW Greenland and their responses to climate oscillations in the past.
Effektiv start/slut dato1/04/2431/12/25


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