Sea-ice retreat may decrease carbon export and vertical microbial connectivity in the Eurasian Arctic basins [post]

Eduard Fadeev, Andreas Rogge, Simon Ramondenc, Eva-Maria Nöthig, Claudia Wekerle, Christina Bienhold, Ian Salter, Anya Waite, Laura Hehemann, Antje Boetius, Morten Iversen
2020 unpublished
Arctic Ocean sea-ice cover is shrinking due to warming. Long-term sediment trap data show 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 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, combined with microbial source
more » ... king revealed that larger aggregates from sea-ice and under-ice diatom blooms were responsible for higher export efficiency and vertical microbial connectivity. During early summer, Phaeocystis aggregates dominated the ice-free regions and exported two-fold less carbon than diatom aggregates in ice-covered regions, and also less surface-born microbial clades to the deep-sea. This suggests that continuous ice-loss will further decrease pelagic-benthic coupling, impacting the quantity and quality of food input due to formation of slow-settling aggregates, with potential repercussions for Arctic deep-sea ecosystems.
doi:10.21203/rs.3.rs-101878/v1 fatcat:43pw3akc4bfa7dnnbdcbqhnzn4