Molecular tools are reshaping biodiversity monitoring by enabling the detection of species from trace DNA released into the environment. In this context, environmental DNA (eDNA) represents a sensitive and non-invasive approach for surveying species presence in environmental matrices, complementing other conventional surveys. eDNA analysis is particularly suited for aquatic environments and can be applied to a wide range of purposes, including the detection and monitoring of invasive species. Indeed, when coupled with targeted amplification assays, eDNA-based surveillance can provide rapid presence/absence information to support early warning systems, management decisions, and mitigation actions.

Among targeted molecular approaches, loop-mediated isothermal amplification (LAMP) is particularly suitable for rapid eDNA detection because it does not require thermal cycling, can be performed with simple equipment, and shows high sensitivity and specificity. These features make LAMP a promising tool for scalable surveillance programs, especially in coastal and transitional environments where fast detection is crucial to guide timely management actions.

Here, we developed and validated a LAMP-based assay targeting a short mitochondrial DNA region for the rapid detection of the Atlantic blue crab Callinectes sapidus, an invasive crab that is currently expanding across the Mediterranean basin. The species has become established in several Mediterranean areas, where its spread has been associated with brackish lagoons, estuaries, shallow coastal habitats, and areas of high benthic productivity. Its broad diet, predatory behaviour, and interactions with fisheries raise ecological and socio-economic concerns, making this species a priority target for early detection and monitoring. The assay was designed to support fast, species-specific detection of C. sapidus from eDNA samples, providing a practical tool for the surveillance of invaded and at-risk Mediterranean habitats. Overall, this approach can contribute to more timely and effective monitoring of C. sapidus and support rapid management responses in areas vulnerable to its establishment and spread.