Particle production by mesopelagic fauna enhances deep-ocean carbon sequestration

Particle production by mesopelagic fauna enhances deep-ocean carbon sequestration | 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 Physical Sciences - Article Particle production by mesopelagic fauna enhances deep-ocean carbon sequestration Daniel Clements, Daniele Bianchi, Thomas Weber, Rainer Kiko, Lars Stemmann This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6465812/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Oceanic carbon sequestration via the biological pump operates through two main export pathways: gravitational sinking of particulate organic carbon (POC) from the surface and injection at depth by migrating fauna. Where the exported POC remineralizes in the water column critically determines the longevity of carbon storage. However, an incomplete view of the organic particle dynamics over depth hinders our understanding of POC flux attenuation and its role in carbon sequestration. Here, we combine observations from in situ particle camera observations (Underwater Vision Profilers; UVP5) with machine learning and empirical algorithms to reconstruct three-dimensional particle size distributions and sinking POC fluxes. We find increased particle biovolume and size in the central mesopelagic zone (400-800 m depth), coinciding with stabilized or even enhanced POC flux, consistent with particle injection by mesopelagic fauna. Assessment of the two export pathways indicates that animal-mediated injection contributes nearly as much to carbon sequestration as the gravitational pathway, despite representing only a small fraction of the total global carbon export. This apparent paradox can be explained by deeper, more efficient sequestration via animal-mediated export, particularly in low- latitude regions with shallower gravitational flux attenuation. These findings point to underappreciated sensitivities of oceanic carbon sequestration to climate and human pressures on mesopelagic fauna. Earth and environmental sciences/Biogeochemistry/Carbon cycle Earth and environmental sciences/Ocean sciences/Marine chemistry Earth and environmental sciences/Climate sciences/Biogeochemistry/Carbon cycle Full Text Additional Declarations There is NO Competing Interest. Supplementary Files FinalSIfigs.pdf SI tables and figures Cite Share Download PDF Status: Under Review Version 1 posted 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-6465812","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Physical Sciences - Article","associatedPublications":[],"authors":[{"id":444297661,"identity":"45c4c5b3-91ed-4423-9865-66201dc9d68e","order_by":0,"name":"Daniel 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Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-6465812/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6465812/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Oceanic carbon sequestration via the biological pump operates through two main export\r\npathways: gravitational sinking of particulate organic carbon (POC) from the surface and\r\ninjection at depth by migrating fauna. Where the exported POC remineralizes in the water\r\ncolumn critically determines the longevity of carbon storage. However, an incomplete\r\nview of the organic particle dynamics over depth hinders our understanding of POC flux\r\nattenuation and its role in carbon sequestration. Here, we combine observations from in\r\nsitu particle camera observations (Underwater Vision Profilers; UVP5) with machine\r\nlearning and empirical algorithms to reconstruct three-dimensional particle size\r\ndistributions and sinking POC fluxes. We find increased particle biovolume and size in\r\nthe central mesopelagic zone (400-800 m depth), coinciding with stabilized or even\r\nenhanced POC flux, consistent with particle injection by mesopelagic fauna. Assessment\r\nof the two export pathways indicates that animal-mediated injection contributes nearly as\r\nmuch to carbon sequestration as the gravitational pathway, despite representing only a\r\nsmall fraction of the total global carbon export. This apparent paradox can be explained\r\nby deeper, more efficient sequestration via animal-mediated export, particularly in low-\r\nlatitude regions with shallower gravitational flux attenuation. These findings point to\r\nunderappreciated sensitivities of oceanic carbon sequestration to climate and human\r\npressures on mesopelagic fauna.","manuscriptTitle":"Particle production by mesopelagic fauna enhances deep-ocean carbon\nsequestration","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-18 03:51:34","doi":"10.21203/rs.3.rs-6465812/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-geoscience","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"ngeo","sideBox":"Learn more about [Nature Geoscience](http://www.nature.com/ngeo/)","snPcode":"","submissionUrl":"","title":"Nature Geoscience","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Research","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"1b46397f-ab75-48a7-b3e9-2168b03cea72","owner":[],"postedDate":"April 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":47301789,"name":"Earth and environmental sciences/Biogeochemistry/Carbon cycle"},{"id":47301790,"name":"Earth and environmental sciences/Ocean sciences/Marine chemistry"},{"id":47301791,"name":"Earth and environmental sciences/Climate sciences/Biogeochemistry/Carbon cycle"}],"tags":[],"updatedAt":"2025-05-17T16:35:08+00:00","versionOfRecord":[],"versionCreatedAt":"2025-04-18 03:51:34","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6465812","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6465812","identity":"rs-6465812","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}