Climate-driven environmental changes and anthropogenic activities can result in the proliferation of opportunistic and formidable non-indigenous aquatic species, such as jellyfish that cause envenomation and various ecological disruptions at the community-ecosystem level. For the present study, we developed an RPA-CRISPR-Cas12a eDNA assay for the early detection of Chrysaora pacifica jellyfish. Field validation of the assay, which used eDNA samples collected in Jinhae Bay over eight months of time-series monitoring, revealed that detection of the species peaked in the month of June followed by May. This correlated with results of digital polymerase chain reaction amplification (dPCR) that quantified C. pacifica eDNA and with results of eDNA metabarcoding. The C. pacifica eDNA assays were also corroborated by reports from a citizen science–based jellyfish-monitoring program operated by the National Institute of Fisheries Science of South Korea. Our RPA-CRISPR/Cas eDNA assay can therefore be an efficient alternative to traditional tools for the early detection of outbreaks of non-indigenous or harmful species in marine ecosystems.

Environmental DNA,Recombinase polymerase amplification,Chrysaora pacifica,Jinhae Bay,dPCR,metabarcoding