Winter sediment resuspension in a submarine canyon drives the offshore export of toxigenic Alexandrium catenella cysts

Winter sediment resuspension in a submarine canyon drives the offshore export of toxigenic Alexandrium catenella cysts | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Winter sediment resuspension in a submarine canyon drives the offshore export of toxigenic Alexandrium catenella cysts Florian Jacques, Audrey Limoges, Michel Gosselin, André Rochon, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9153776/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 18 You are reading this latest preprint version Abstract Harmful algal blooms (HABs) caused by the toxigenic dinoflagellate Alexandrium catenella recur regularly in the Lower St. Lawrence Estuary (LSLE, eastern Canada). Using quantitative polymerase chain reaction (qPCR) to detect A. catenella DNA as a proxy for cyst abundance in the Pointe-des-Monts canyon system, we show that resting cysts are concentrated in nearshore sediments and on the canyon fan, but are depleted along the canyon axis. Sediment traps reveal that major cyst resuspensions occur exclusively during winter storms under ice-free conditions, with peaks in A. catenella DNA fluxes coinciding with turbidity currents and high total particulate matter export. These events effectively flush coastal cysts offshore, creating a negative feedback loop that reduces subsequent local bloom potential. Conversely, climate change-driven increases in summer-to-autumn storm frequency and intensity could resuspend cysts under optimal proliferation conditions. Sedimentary ancient DNA in a 210 Pb-dated sediment core also demonstrates that qPCR reliably records known historical A. catenella bloom events. These results highlight the critical, yet underappreciated, role of submarine canyon systems and storm-driven sediment dynamics in modulating A. catenella bloom risks, and suggest that ongoing climate-driven shifts in sea-ice cover and storm seasonality are likely to influence future HABs in the LSLE and similar high-latitude systems. Earth and environmental sciences/Climate sciences Biological sciences/Ecology Earth and environmental sciences/Ecology Earth and environmental sciences/Environmental sciences Earth and environmental sciences/Ocean sciences Alexandrium catenella dinoflagellate cyst resuspension Harmful Algal Blooms qPCR sedimentary ancient DNA sediment dynamics particulate matter export sediment traps submarine canyons Full Text Additional Declarations No competing interests reported. Supplementary Files SupplementaryinformationJacquesetalWintersedimentresuspensioninasubmarine.docx Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 20 Apr, 2026 Reviews received at journal 19 Apr, 2026 Reviews received at journal 16 Apr, 2026 Reviews received at journal 14 Apr, 2026 Reviews received at journal 11 Apr, 2026 Reviews received at journal 02 Apr, 2026 Reviewers agreed at journal 30 Mar, 2026 Reviewers agreed at journal 29 Mar, 2026 Reviewers agreed at journal 27 Mar, 2026 Reviewers agreed at journal 27 Mar, 2026 Reviewers agreed at journal 27 Mar, 2026 Reviewers agreed at journal 26 Mar, 2026 Reviewers agreed at journal 26 Mar, 2026 Reviewers invited by journal 26 Mar, 2026 Editor invited by journal 20 Mar, 2026 Editor assigned by journal 19 Mar, 2026 Submission checks completed at journal 19 Mar, 2026 First submitted to journal 17 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9153776","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":615038195,"identity":"81fe8624-f530-490c-9c3b-5e84c423d40f","order_by":0,"name":"Florian Jacques","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+ElEQVRIiWNgGAWjYBAC++NAIgGI2RsgAnIEtRgwQ7UwQrUYE6eFAUlLYgNhLczHPjyoucPA2H744W2eirr0DceTn31gqLHDqcWemS15RsKxZwyMPWnG1jxnDuduOPPMeAbDsWQ8tvAYMySwHQY6LIdNmrftQO6GGwnGQB4zAS3/gFr63wC1/KtLN7iR/hmopR6/lsS2wwyCM0C2NDAnGNzIAdlyGI8WtmSGxL7DPNISz4wt5xw7bDjzzJtihoRjx3FrYW8+zPjj22E5Pv7khzfe1NTJ8x1P38zwoaYapxYY4AEREhB2AiRyiQIILaNgFIyCUTAKkAAABqRNTuPGgSYAAAAASUVORK5CYII=","orcid":"","institution":"Université du Québec à Rimouski","correspondingAuthor":true,"prefix":"","firstName":"Florian","middleName":"","lastName":"Jacques","suffix":""},{"id":615038196,"identity":"76db832f-4a84-4555-99dc-65f6db16b392","order_by":1,"name":"Audrey Limoges","email":"","orcid":"","institution":"University of New Brunswick","correspondingAuthor":false,"prefix":"","firstName":"Audrey","middleName":"","lastName":"Limoges","suffix":""},{"id":615038197,"identity":"a1d2a954-73dd-458b-8077-e18b2ba30092","order_by":2,"name":"Michel Gosselin","email":"","orcid":"","institution":"Université du Québec à Rimouski","correspondingAuthor":false,"prefix":"","firstName":"Michel","middleName":"","lastName":"Gosselin","suffix":""},{"id":615038198,"identity":"8db0d32d-f631-42a4-892c-36e9cf20f890","order_by":3,"name":"André Rochon","email":"","orcid":"","institution":"Université du Québec à Rimouski","correspondingAuthor":false,"prefix":"","firstName":"André","middleName":"","lastName":"Rochon","suffix":""},{"id":615038199,"identity":"f9d989b7-b978-4c03-8e24-cd6911a34aed","order_by":4,"name":"El Mahdi Bendif","email":"","orcid":"","institution":"Université du Québec à Rimouski","correspondingAuthor":false,"prefix":"","firstName":"El","middleName":"Mahdi","lastName":"Bendif","suffix":""},{"id":615038201,"identity":"f501d9ad-22b3-4305-9734-8255f62f9f21","order_by":5,"name":"Jean-Carlos Montero-Serrano","email":"","orcid":"","institution":"Université du Québec à Rimouski","correspondingAuthor":false,"prefix":"","firstName":"Jean-Carlos","middleName":"","lastName":"Montero-Serrano","suffix":""},{"id":615038202,"identity":"b30913a7-669f-4fbf-9696-814e929bb55b","order_by":6,"name":"Alexandre Normandeau","email":"","orcid":"","institution":"Geological Survey of Canada - 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Using quantitative polymerase chain reaction (qPCR) to detect \u003cem\u003eA. catenella\u003c/em\u003e DNA as a proxy for cyst abundance in the Pointe-des-Monts canyon system, we show that resting cysts are concentrated in nearshore sediments and on the canyon fan, but are depleted along the canyon axis. Sediment traps reveal that major cyst resuspensions occur exclusively during winter storms under ice-free conditions, with peaks in \u003cem\u003eA. catenella\u003c/em\u003e DNA fluxes coinciding with turbidity currents and high total particulate matter export. These events effectively flush coastal cysts offshore, creating a negative feedback loop that reduces subsequent local bloom potential. Conversely, climate change-driven increases in summer-to-autumn storm frequency and intensity could resuspend cysts under optimal proliferation conditions. Sedimentary ancient DNA in a \u003csup\u003e210\u003c/sup\u003ePb-dated sediment core also demonstrates that qPCR reliably records known historical \u003cem\u003eA. catenella\u003c/em\u003e bloom events. 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