From the Balkans to France: the threatened range-restricted freshwater mussel Unio carneus revealed as an introduced species by environmental DNA

From the Balkans to France: the threatened range-restricted freshwater mussel Unio carneus revealed as an introduced species by environmental DNA | 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 From the Balkans to France: the threatened range-restricted freshwater mussel Unio carneus revealed as an introduced species by environmental DNA Vincent Prié, Luc Clément, Coline Gaboriaud, Miguel Gailledrat, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7583386/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 04 Jan, 2026 Read the published version in Biological Invasions → Version 1 posted 5 You are reading this latest preprint version Abstract Environmental DNA (eDNA) is a powerful, non-invasive tool for detecting invasive species at an early stage, even when populations are small or elusive. Its high sensitivity can reveal introductions that might otherwise go unnoticed for decades. Large-scale eDNA surveys of freshwater bivalves across French rivers uncovered the presence of Unio carneus, a mussel species endemic to the Drin Basin in the Balkans and threatened in its native range. Identification was confirmed through genetic analysis of live specimens. In France, the distribution of U. carneus largely overlaps with that of the Albanian roach Pachychilon pictum, a fish introduced from the same region in the late 1980s, suggesting introduction via parasitic larvae on its host. However, detections outside the fish’s known range raise questions about alternative hosts and the mussel’s ability to adapt to local conditions. The French population shows low genetic diversity, consistent with a founder effect, and appears to be of low invasiveness to date. This case illustrates the value of eDNA for uncovering overlooked introductions and highlights the conservation paradox posed by species that are threatened in their native range yet may act as emerging invaders elsewhere. Full Text Cite Share Download PDF Status: Published Journal Publication published 04 Jan, 2026 Read the published version in Biological Invasions → Version 1 posted Reviewers agreed at journal 23 Sep, 2025 Reviewers invited by journal 23 Sep, 2025 Editor invited by journal 12 Sep, 2025 Editor assigned by journal 11 Sep, 2025 First submitted to journal 10 Sep, 2025 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. 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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-7583386","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":519470597,"identity":"7bab523f-bf87-453e-a423-4287936042a2","order_by":0,"name":"Vincent 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