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

• Published in: Communications biology Vol. 4; no. 1; pp. 1255 - 13
• Main Authors: Fadeev, Eduard, Rogge, Andreas, Ramondenc, Simon, Nöthig, Eva-Maria, Wekerle, Claudia, Bienhold, Christina, Salter, Ian, Waite, Anya M., Hehemann, Laura, Boetius, Antje, Iversen, Morten H.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.11.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 14/63; 631/158/2446/2447; 631/326/47; Archaea - metabolism; Arctic Regions; Bacteria - metabolism; Biodiversity and Ecology; Biology; Biomedical and Life Sciences; Carbon; Carbon Cycle; Connectivity; Deep sea; Dispersal; Efficiency; Environmental Sciences; Food webs; Ice Cover - chemistry; Ice Cover - microbiology; Life Sciences; Microbiota - physiology; Oceans and Seas; Particulate organic carbon; Phytoplankton; rRNA 16S; Sea ice; Water column; Arctic Regions; Arctic Ocean; Fram Strait
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-021-02776-w

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. Fadeev et al. explore carbon export dynamics along the water column using microscopic analysis, 16S rRNA gene amplicon sequencing, and physical modeling of data from long-term sediment traps in the Fram Strait. Their results indicate that larger aggregates from sea-ice and under-ice diatom blooms are responsible for higher export efficiency and vertical microbial connectivity, suggesting that continuous sea-ice loss may result in decreased pelagic-benthic coupling, with resultant impacts on marine food webs.