High biomass turnover rates of endosymbiotic nitrogen-fixing cyanobacteria in the western Bering Sea

• Published in: Limnology and Oceanography Letters
• Main Authors: Cheung, Shun Yan, Liu, Kailin, Turk-Kubo, Kendra A., Nishioka, Jun, Suzuki, Koji, Landry, Michael R., Zehr, Jonathan P., Leung, Sze Ki, Deng, Lixia, Liu, Hongbin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Bering Sea; Anadyr; Anadyr’; Anadyr'
• Online Access: http://repository.hkust.edu.hk/ir/Record/1783.1-121249; https://doi.org/10.1002/lol2.10267; http://lbdiscover.ust.hk/uresolver?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rfr_id=info:sid/HKUST:SPI&rft.genre=article&rft.issn=2378-2242&rft.volume=&rft.issue=&rft.date=2022&rft.spage=&rft.aulast=Cheung&rft.aufirst=&rft.atitle=High+biomass+turnover+rates+of+endosymbiotic+nitrogen-fixing+cyanobacteria+in+the+western+Bering+Sea&rft.title=LIMNOLOGY+AND+OCEANOGRAPHY+LETTERS; http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=LinksAMR&SrcApp=PARTNER_APP&DestLinkType=FullRecord&DestApp=WOS&KeyUT=000820929000001; http://www.scopus.com/record/display.url?eid=2-s2.0-85133447384&origin=inward

Recent studies have described active nitrogen fixation in high-latitude waters, but the ecological controls on the occurrence or activity of nitrogen-fixing organisms (diazotrophs) in such systems remain unknown. Turnover rates and top-down controls are also general knowledge gaps for marine diazotrophs. We detected abundant UCYN-A (endosymbiotic nitrogen-fixing cyanobacteria) in the Gulf of Anadyr, western Bering Sea, which correlated with high dissolved iron to dissolved inorganic nitrogen ratios (Fe : DIN) due to riverine input. Growth and grazing mortality of UCYN-A sublineages were almost balanced with higher biomass-turnover rates compared to the whole phytoplankton community, indicating selective grazing of UCYN-A in nitrogen-depleted waters. Grazing rates on UCYN-A1 (small cells) were higher than for UCYN-A2/3/4 (large cells), consistent with the general size dependence of phytoplankton growth and grazing mortality. We found that Fe : DIN is a major determinant of UCYN-A abundances in high-latitude waters, where UCYN-A could make substantial contributions to plankton food-web cycling.