Nutrient–Carbon Interactions and Monsoon-Driven Harmful Algal Bloom Dynamics in the Bosaso Coastal Waters of Puntland, Somalia (2023–2025)

Nutrient–Carbon Interactions and Monsoon-Driven Harmful Algal Bloom Dynamics in the Bosaso Coastal Waters of Puntland, Somalia (2023–2025) | 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 Short Report Nutrient–Carbon Interactions and Monsoon-Driven Harmful Algal Bloom Dynamics in the Bosaso Coastal Waters of Puntland, Somalia (2023–2025) Abdulahi Jimale Said This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8564438/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Harmful algal blooms (HABs) pose a growing ecological and economic risk in tropical shelf seas, yet their drivers remain poorly constrained along the Somali coast, one of the least monitored upwelling systems of the western Indian Ocean. This study quantifies the spatio-temporal dynamics of chlorophyll-a and associated biogeochemical variables in the Bosaso coastal waters (48.5°–51.9° E; 8.8°–12.7° N) from January 2023 to October 2025 using Copernicus Marine Environment Monitoring Service (CMEMS) reanalysis data. Daily surface observations of chlorophyll-a, nitrate (NO₃), phosphate (PO₄), silicate (Si), and surface partial pressure of CO₂ (spCO₂) were harmonized, regridded, and merged into a unified dataset. Bloom events were identified using a 90th-percentile chlorophyll-a threshold (1.293 mg m⁻³), while a logistic regression model evaluated bloom probability from nutrient–carbon interactions. Results reveal strong seasonal and interannual variability linked to monsoon-driven upwelling, with elevated nutrients and reduced spCO₂ coinciding with bloom peaks. Chlorophyll-a exhibited significant correlations with NO₃ (r = 0.85), PO₄ (r = 0.73), and Si (r = 0.62), confirming nutrient enrichment as the primary driver of bloom initiation. The logistic model achieved high predictive performance (AUC = 0.97), indicating that simple nutrient and CO₂ metrics can serve as effective early-warning indicators. These findings provide the first quantitative HAB baseline for Puntland’s coastal waters and demonstrate a reproducible computational workflow for regional HAB monitoring and management. Harmful algal blooms chlorophyll-a nutrients monsoon upwelling Somali coast Copernicus Marine Service Bosaso logistic regression spCO₂ Arabian Sea phytoplankton dynamics climate variability coastal productivity biogeochemical reanalysis early-warning system Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-8564438","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Short Report","associatedPublications":[],"authors":[{"id":573520215,"identity":"ac97c28a-a143-43ab-99bc-d0f7111e5c59","order_by":0,"name":"Abdulahi Jimale 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(2023–2025)\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Harmful algal blooms, chlorophyll-a, nutrients, monsoon upwelling, Somali coast, Copernicus Marine Service, Bosaso, logistic regression, spCO₂, Arabian Sea, phytoplankton dynamics, climate variability, coastal productivity, biogeochemical reanalysis, early-warning system","lastPublishedDoi":"10.21203/rs.3.rs-8564438/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8564438/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHarmful algal blooms (HABs) pose a growing ecological and economic risk in tropical shelf seas, yet their drivers remain poorly constrained along the Somali coast, one of the least monitored upwelling systems of the western Indian Ocean. This study quantifies the spatio-temporal dynamics of chlorophyll-a and associated biogeochemical variables in the Bosaso coastal waters (48.5\u0026deg;\u0026ndash;51.9\u0026deg; E; 8.8\u0026deg;\u0026ndash;12.7\u0026deg; N) from January 2023 to October 2025 using Copernicus Marine Environment Monitoring Service (CMEMS) reanalysis data. Daily surface observations of chlorophyll-a, nitrate (NO₃), phosphate (PO₄), silicate (Si), and surface partial pressure of CO₂ (spCO₂) were harmonized, regridded, and merged into a unified dataset. Bloom events were identified using a 90th-percentile chlorophyll-a threshold (1.293 mg m⁻\u0026sup3;), while a logistic regression model evaluated bloom probability from nutrient\u0026ndash;carbon interactions. Results reveal strong seasonal and interannual variability linked to monsoon-driven upwelling, with elevated nutrients and reduced spCO₂ coinciding with bloom peaks. Chlorophyll-a exhibited significant correlations with NO₃ (r\u0026thinsp;=\u0026thinsp;0.85), PO₄ (r\u0026thinsp;=\u0026thinsp;0.73), and Si (r\u0026thinsp;=\u0026thinsp;0.62), confirming nutrient enrichment as the primary driver of bloom initiation. The logistic model achieved high predictive performance (AUC\u0026thinsp;=\u0026thinsp;0.97), indicating that simple nutrient and CO₂ metrics can serve as effective early-warning indicators. These findings provide the first quantitative HAB baseline for Puntland\u0026rsquo;s coastal waters and demonstrate a reproducible computational workflow for regional HAB monitoring and management.\u003c/p\u003e","manuscriptTitle":"Nutrient–Carbon Interactions and Monsoon-Driven Harmful Algal Bloom Dynamics in the Bosaso Coastal Waters of Puntland, Somalia (2023–2025)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-13 04:20:40","doi":"10.21203/rs.3.rs-8564438/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a49156fe-7495-46e2-ba50-e3f3204db8de","owner":[],"postedDate":"January 13th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-01T08:42:13+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-13 04:20:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8564438","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8564438","identity":"rs-8564438","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}