The paleogenetic signatures of marine biota reveal their responses to the Holocene Thermal Maximum

Biodiversity plays an essential role in the functioning of marine ecosystems, and ultimately their health and resilience. Yet, as an overwhelming number of functional groups do not leave a fossil record (e.g., zooplankton, jellyfish, and soft-bodied benthic fauna), our understanding of past marine biodiversity changes is inadequate to make confident projections. The retrieval of sedimentary ancient DNA (sedaDNA), the molecular footprints of past biota from marine sediment cores, has been a game changer in this regard. It allows us to trace species, e.g. with soft body parts or skeletal components prone to dissolution, offering a more complete picture of ecosystem-level responses over time. As anthropogenic climate warming accelerates change in Arctic marine environments, the need for long-term ecological baselines has become increasingly urgent. Past ecosystem responses to natural climate variability can provide critical context for interpreting and anticipating present and future changes. Here, we will present a sedaDNA record from Melville Bay off North-West Greenland, covering the past ~12,000 years. By characterizing the changes of marine biota in response to the Holocene Thermal Maximum, we aim to establish natural baselines for marine biodiversity to place recent and projected changes in context. In addition to a broad reconstruction of community change, we will highlight taxonomic groups which are of high ecological, cultural, and economic relevance to Greenland, such as primary producers including seaweeds, (gelatinous) zooplankton, fish, and marine mammals. We invite dialogue on how sedaDNA research can support knowledge-driven approaches to managing Arctic marine ecosystems under climate warming.