Exudates from the invasive macroalga Rugulopteryx okamurae inhibit early development in sea urchins.

Exudates from the invasive macroalga Rugulopteryx okamurae inhibit early development in sea urchins. | 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 Research Article Exudates from the invasive macroalga Rugulopteryx okamurae inhibit early development in sea urchins. RODRIGO ALMEDA, Aurora Díaz, Yefermin Darias, Milagros Rico, Ricardo Haroun This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9359816/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract In recent years, the Pacific brown macroalga Rugulopteryx okamurae has rapidly expanded across Mediterranean and Atlantic coasts, generating major ecological and socio‑economic impacts. In this study we examined the effects of exudates released by R. okamurae on the early developmental stages of two autochthonous sea urchin species, Paracentrotus lividus and Arbacia lixula, which are key benthic grazers in the invaded regions. Fertilized eggs were exposed for three days to different concentrations of R. okamurae exudates, and subsequent effects on survival, growth, and developmental abnormalities were determined for both sea urchin species. Acute exposure to 50 g L⁻¹ exudates caused about 90% embryonic mortality in both species. Lower concentrations significantly reduced larval growth and increased malformations. Median effect concentrations for growth inhibition were 16 g L⁻¹ for P. lividus and 14 g L⁻¹ for A. lixula, indicating similar sensitivity. Malformations increased significantly at concentrations of 0.5 g L⁻¹ in P. lividusand at 5 g L⁻¹ in A. lixula. The HPLC-MS analysis of R. okamurae exudates confirmed the presence of several bioactive polyphenols, with vanillic acid exhibiting the highest concentration (1.73 ± 0.09 µg L-1). Overall, our results show that R. okamurae exudates strongly inhibit the early development stages of native sea urchins. The presence of high biomass of this invasive alga is therefore likely to reduce larval survival and recruitment, driving sustained declines in their benthic populations. As these key grazers play a central role in regulating macroalgal community dynamics, their reduction would weaken grazing pressure and create conditions that further facilitate the invasion and ecological impacts of R. okamuraein the invaded Atlantic and Mediterranean rocky shores. Full Text Cite Share Download PDF Status: Under Review Version 1 posted Reviewers invited by journal 17 Apr, 2026 Editor invited by journal 15 Apr, 2026 Editor assigned by journal 09 Apr, 2026 First submitted to journal 08 Apr, 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. 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. 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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-9359816","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":624774883,"identity":"4759f256-a6f6-49c5-90cb-43f6f0aaf62c","order_by":0,"name":"RODRIGO ALMEDA","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+UlEQVRIiWNgGAWjYHACA4YEEMUOxDwMNgx8xGthBmtJY2AjSgsDQsthwlrM25u3fXjwy4aBv5k78cGbmvOJbdLtFz8wVNTh1CJz5ljxjMS+NAaJw7ybDeccu53YJnOmWILhzGGcWiQkcowZEnuACg7zbpPmYQNqkchJY2BsO0BYi/xh3u2/ef6dg2r5h9thYC0JPw4zGABtYeZtOwDUkn6MgbGBGbcWnmPFDIkNaTyGQL9Izu1LNgb6hVki4Rgev7A3b2b88cdGTu5478YPb77ZyfZLtz/88KEGt8PAgLENGCNIFkMjFy/4g2rxA4IaRsEoGAWjYEQBAHUfUjbCQjnvAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-0090-112X","institution":"ULPGC: Universidad de las Palmas de Gran Canaria","correspondingAuthor":true,"prefix":"","firstName":"RODRIGO","middleName":"","lastName":"ALMEDA","suffix":""},{"id":624774884,"identity":"a105d0bf-0970-4549-8249-e81758a85856","order_by":1,"name":"Aurora Díaz","email":"","orcid":"","institution":"ULPGC: Universidad de las Palmas de Gran Canaria","correspondingAuthor":false,"prefix":"","firstName":"Aurora","middleName":"","lastName":"Díaz","suffix":""},{"id":624774885,"identity":"4501b39a-7bfb-46b6-a436-8f3a34776f32","order_by":2,"name":"Yefermin Darias","email":"","orcid":"","institution":"ULPGC: Universidad de las Palmas de Gran Canaria","correspondingAuthor":false,"prefix":"","firstName":"Yefermin","middleName":"","lastName":"Darias","suffix":""},{"id":624774886,"identity":"60b9b301-d8c7-4858-8e3b-374459ba9ef0","order_by":3,"name":"Milagros Rico","email":"","orcid":"","institution":"ULPGC: Universidad de las Palmas de Gran Canaria","correspondingAuthor":false,"prefix":"","firstName":"Milagros","middleName":"","lastName":"Rico","suffix":""},{"id":624774887,"identity":"51098c05-c4d3-47c5-be17-2a951ffa8760","order_by":4,"name":"Ricardo Haroun","email":"","orcid":"","institution":"ULPGC: Universidad de las Palmas de Gran Canaria","correspondingAuthor":false,"prefix":"","firstName":"Ricardo","middleName":"","lastName":"Haroun","suffix":""}],"badges":[],"createdAt":"2026-04-08 17:17:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9359816/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9359816/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107706770,"identity":"f5434f90-7b27-44d8-b92b-edd61b7dae80","added_by":"auto","created_at":"2026-04-24 09:18:42","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1134061,"visible":true,"origin":"","legend":"","description":"","filename":"ExudatesRugulopteryxokamuraesubmittedtoBI.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9359816/v1_covered_a6fb71a2-3b9e-42c5-9878-6dc652791124.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eExudates from the invasive macroalga Rugulopteryx okamurae inhibit early development in sea urchins. \u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"biological-invasions","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"binv","sideBox":"Learn more about [Biological Invasions](https://www.springer.com/journal/10530)","snPcode":"10530","submissionUrl":"https://submission.nature.com/new-submission/10530/3","title":"Biological Invasions","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-9359816/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9359816/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"In recent years, the Pacific brown macroalga Rugulopteryx okamurae has rapidly expanded across Mediterranean and Atlantic coasts, generating major ecological and socio‑economic impacts. In this study we examined the effects of exudates released by R. okamurae on the early developmental stages of two autochthonous sea urchin species, Paracentrotus lividus and Arbacia lixula, which are key benthic grazers in the invaded regions. Fertilized eggs were exposed for three days to different concentrations of R. okamurae exudates, and subsequent effects on survival, growth, and developmental abnormalities were determined for both sea urchin species. Acute exposure to 50 g L⁻¹ exudates caused about 90% embryonic mortality in both species. Lower concentrations significantly reduced larval growth and increased malformations. Median effect concentrations for growth inhibition were 16 g L⁻¹ for P. lividus and 14 g L⁻¹ for A. lixula, indicating similar sensitivity. Malformations increased significantly at concentrations of 0.5 g L⁻¹ in P. lividusand at 5 g L⁻¹ in A. lixula. The HPLC-MS analysis of R. okamurae exudates confirmed the presence of several bioactive polyphenols, with vanillic acid exhibiting the highest concentration (1.73 ± 0.09 µg L-1). Overall, our results show that R. okamurae exudates strongly inhibit the early development stages of native sea urchins. The presence of high biomass of this invasive alga is therefore likely to reduce larval survival and recruitment, driving sustained declines in their benthic populations. 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