Sea ice presence is linked to higher carbon export and vertical microbial connectivity in the Eurasian Arctic Ocean

• Published in: Communications Biology
• Main Authors: Fadeev, Eduard, Rogge, Andreas, Ramondenc, Simon, Nöthig, Eva-Maria, Wekerle, Claudia, Bienhold, Christina, Salter, Ian, Waite, Anya, Hehemann, Laura, Boetius, Antje, Iversen, Morten
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2021
• Subjects: Arctic; Arctic Ocean; Fram Strait; Phytoplankton; Sea ice
• Online Access: https://epic.awi.de/id/eprint/54926/; https://hdl.handle.net/10013/epic.ee4d6a2d-2355-4989-a18e-6c0568318f0b

Arctic Ocean sea ice cover is shrinking due to warming. Long-term sediment trap data shows higher export efficiency of particulate organic carbon in regions with seasonal sea ice compared to regions without sea ice. To investigate this sea-ice enhanced export, we compared how different early summer phytoplankton communities in seasonally ice-free and ice-covered regions of the Fram Strait affect carbon export and vertical dispersal of microbes. In situ collected aggregates revealed two-fold higher carbon export of diatom-rich aggregates in ice-covered regions, compared to Phaeocystis aggregates in the ice-free region. Using microbial source tracking, we found that ice-covered regions were also associated with more surface-born microbial clades exported to the deep sea. Taken together, our results showed that ice-covered regions are responsible for high export efficiency and provide strong vertical microbial connectivity. Therefore, continuous sea-ice loss may decrease the vertical export efficiency, and thus the pelagic-benthic coupling, with potential repercussions for Arctic deep-sea ecosystems.