{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T08:07:30Z","timestamp":1788336450435,"version":"build-2803163510"},"reference-count":13,"publisher":"Oxford University Press (OUP)","issue":"1","license":[{"start":{"date-parts":[[2025,10,24]],"date-time":"2025-10-24T00:00:00Z","timestamp":1761264000000},"content-version":"vor","delay-in-days":296,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"MeNARP Project"},{"name":"M174 N-Amazon","award":["GPF19-1-13"],"award-info":[{"award-number":["GPF19-1-13"]}]},{"name":"German Federal Ministry of Education and Research","award":["03F0626A"],"award-info":[{"award-number":["03F0626A"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,1,17]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Diazotrophy is the most important nitrogen source in the oligotrophic surface ocean, but the organisms involved and their contributions are incompletely understood due to limited observations. Only diazotrophic organisms possess the nifH gene to reduce dinitrogen to ammonium, but their distribution and activity can only be quantified through sampling and experiments during research cruises. Some recent studies document small diatoms with symbionts able to fix nitrogen, a new source of biologically available nitrogen in addition to the well-known cyanobacterial species such as Trichodesmium or symbionts of haptophytes (UCYN-A) and diatoms (Diatom\u2013Diazotroph Associations, or DDAs). Here, we document a very active symbiosis between small pennate diatoms such as Mastogloia and Haslea with rhizobial and cyanobacterial symbionts in waters of the Western tropical North Atlantic influenced by the Amazon River plume. We used NanoSIMS analysis of 15N2 tracer experiments to quantify high rates of nitrogen fixation in generally abundant, symbiont-bearing pennate diatoms. This newly described symbiosis may contribute a previously unquantified flux of biologically available nitrogen to oceanic systems. Pennate diatoms and their symbionts may close a key gap in our understanding of the supply of nutrients to the ocean and provide a previously unknown biological sink for carbon dioxide.<\/jats:p>","DOI":"10.1093\/ismeco\/ycaf190","type":"journal-article","created":{"date-parts":[[2025,10,22]],"date-time":"2025-10-22T11:51:23Z","timestamp":1761133883000},"source":"Crossref","is-referenced-by-count":3,"title":["Novel pennate diatom symbionts support high N2 fixation rates"],"prefix":"10.1093","volume":"5","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0189-4005","authenticated-orcid":false,"given":"Bhavya S","family":"Panthalil","sequence":"first","affiliation":[{"name":"Department of Biological Oceanography, Leibniz Institute for Baltic Sea Research Warnem\u00fcnde , Rostock 18119 ,","place":["Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4261-3123","authenticated-orcid":false,"given":"Angela","family":"Vogts","sequence":"additional","affiliation":[{"name":"Department of Biological Oceanography, Leibniz Institute for Baltic Sea Research Warnem\u00fcnde , Rostock 18119 ,","place":["Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9502-108X","authenticated-orcid":false,"given":"Mar","family":"Benavides","sequence":"additional","affiliation":[{"name":"National Oceanography Centre, European Way , Southampton SO14 3ZH ,","place":["United Kingdom"]},{"name":"Aix Marseille Univ, Universit\u00e9 de Toulon , CNRS, IRD, MIO UM 110, Marseille 13288 ,","place":["France"]},{"name":"Turing Centre for Living Systems, Aix-Marseille University , Marseille 13009 ,","place":["France"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3451-3042","authenticated-orcid":false,"given":"Matthew J","family":"Harke","sequence":"additional","affiliation":[{"name":"Fisheries and Ocean Health, Gloucester Marine Genomics Institute , Gloucester, MA 01930 ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1909-1726","authenticated-orcid":false,"given":"Christiane","family":"Hassenr\u00fcck","sequence":"additional","affiliation":[{"name":"Department of Biological Oceanography, Leibniz Institute for Baltic Sea Research Warnem\u00fcnde , Rostock 18119 ,","place":["Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1316-5827","authenticated-orcid":false,"given":"Ajit","family":"Subramaniam","sequence":"additional","affiliation":[{"name":"Lamont-Doherty Earth Observatory at Columbia University , Palisades, NY 10964 ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joseph P","family":"Montoya","sequence":"additional","affiliation":[{"name":"School of Biological Sciences, Georgia Institute of Technology , Atlanta, GA 30332 ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5827-9062","authenticated-orcid":false,"given":"Maren","family":"Voss","sequence":"additional","affiliation":[{"name":"Department of Biological Oceanography, Leibniz Institute for Baltic Sea Research Warnem\u00fcnde , Rostock 18119 ,","place":["Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2025,10,24]]},"reference":[{"key":"2025111509465695500_ref1","doi-asserted-by":"publisher","DOI":"10.1093\/femsre\/fuac046","article-title":"Non-cyanobacterial diazotrophs: global diversity, distribution, ecophysiology, and activity in marine waters","volume":"47","author":"Turk-Kubo","year":"2022","journal-title":"FEMS Microbiol Rev"},{"key":"2025111509465695500_ref2","doi-asserted-by":"publisher","first-page":"1546","DOI":"10.1126\/science.1222700","article-title":"Unicellular cyanobacterium symbiotic with a single-celled eukaryotic alga","volume":"337","author":"Thompson","year":"2012","journal-title":"Science."},{"key":"2025111509465695500_ref3","doi-asserted-by":"publisher","first-page":"899","DOI":"10.1038\/s41586-024-07495-w","article-title":"Rhizobia\u2013diatom symbiosis fixes missing nitrogen in the ocean","volume":"630","author":"Tschitschko","year":"2024","journal-title":"Nature."},{"key":"2025111509465695500_ref4","doi-asserted-by":"publisher","first-page":"799","DOI":"10.1038\/s41467-022-28065-6","article-title":"Overlooked and widespread pennate diatom-diazotroph symbioses in the sea","volume":"13","author":"Schvarcz","year":"2022","journal-title":"Nat 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Evol"},{"key":"2025111509465695500_ref8","doi-asserted-by":"publisher","first-page":"11407","DOI":"10.1073\/pnas.1405222111","article-title":"Complete genome of a nonphotosynthetic cyanobacterium in a diatom reveals recent adaptations to an intracellular lifestyle","volume":"111","author":"Nakayama","year":"2014","journal-title":"Proc Natl Acad Sci"},{"key":"2025111509465695500_ref9","doi-asserted-by":"publisher","first-page":"517","DOI":"10.4319\/lo.2007.52.2.0517","article-title":"Influence of the amazon river plume on distributions of free-living and symbiotic cyanobacteria in the western tropical North Atlantic Ocean","volume":"52","author":"Foster","year":"2007","journal-title":"Limnol Oceanogr"},{"key":"2025111509465695500_ref10","doi-asserted-by":"publisher","first-page":"618","DOI":"10.1002\/lno.10448","article-title":"Amazon river influence on nitrogen fixation and export production in the western tropical North 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