Delrieu-Trottin E. auteur aut IRD Bianic M. auteur aut IRD Miaud C. auteur aut IRD Garcia M. auteur aut IRD Arnal V. auteur aut IRD Hocdé Régis auteur aut IRD Cochet Christophe auteur aut IRD Barré N. auteur aut IRD Cornil L. auteur aut IRD Manel S. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Early detection is a crucial tool for identifying the spread of invasive species. In this study, we validated a probe-based quantitative polymerase chain reaction (qPCR) assay for the detection of the invasive Blue Crab, Callinectes sapidus, in the Mediterranean Sea, using 22 initial eDNA environmental samples (eDNA) collected from three coastal lagoons. A subsequent large-scale eDNA sampling campaign (61 samples in 31 sites), conducted in collaboration with local stakeholders, was carried out to map the distribution of C. sapidus along the Occitanie coastline (Western Mediterranean, France). Using eDNA probe-based qPCR, C. sapidus was detected in 32 out of the 61 samples (52%), confirming its presence in 24 out of 31 sites surveyed, including the 13 lagoons where its occurrence had already been reported, as well as two additional lagoons and at sea where no prior records existed. Our results demonstrate the utility of eDNA probe-based qPCR for effective monitoring of the invasive Blue Crab. The integration of eDNA analysis with citizen science observations enhances the monitoring framework, facilitating early detection and contributing to improved management strategies at the very beginning of species colonization when practical actions could be implemented. specialized COI mtDNA crustacean eDNA invasive species invertebrates Mediterranean Sea monitoring qPCR quantitative polymerase chain reaction (qPCR)-based eDNA detection FRANCE MEDITERRANNEE OCCITANIE 036 034 082 35 7 e70179 [9 p.] 2025 1052-7613 https://www.documentation.ird.fr/hor/fdi:010094392 10.1002/aqc.70179 1052-7613 [F B010094392] https://www.documentation.ird.fr/hor/fdi:010094392 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2025-09/010094392.pdf IRD - Base Horizon / Pleins textes 2025-09-24 2025-09-24 fdi:010094392 fre