PCR-based assay for Mya arenaria detection from marine environmental samples and tracking its invasion in coastal ecosystems

The introduction of invasive species into a new environment is one of the most important factors implicated in loss of native biodiversity. Their early detection is indispensable to efficient control and management response, because after their incursion and establishment the eradication is nearly impossible. The Mediterranean Sea is one of the world´s hotspots of biological invasions and existing monitoring programs are often insufficient for effective surveillance of the established invasive populations or early detection of new incursions. The aim of the current study was to design a specific molecular marker for detecting and monitoring the soft shell clam Mya arenaria, listed among 100 Mediterranean Worst Invasive Species, from environmental samples. The 16S marker was designed in silico and validated in vitro on serial dilutions of M. arenaria DNA and other closely related mollusk species; its performance was also tested on complex environmental samples collected from locations in the Baltic Sea with known established M. arenaria population. The new marker allows amplifying small fragments of 279 bp and detecting as low as 0.00103 ng/μl of M. arenaria DNA with no cross-amplification detected. We suggest the use of this and other species-specific markers for targeted surveillance of invasive species and prompt detection of the prospective incursions. Such monitoring approach has the potential to be adopted by citizen science programs due to its easy implementation, minimal technical skills requirements and reasonable amount of associated expenditures.