Development of environmental DNA chip for monitoring the invasive alien fishes in dam reservoirs

Control and prevention of invasive alien species (IAS) are important issues for the environmental management of dam reservoirs. Recently, environmental DNA (eDNA) analysis has been used for monitoring IAS in aquatic ecosystems. In this study, as a simple and user-friendly eDNA method for monitoring IAS, we developed an eDNA chip analysis for monitoring three IAS, largemouth bass Micropterus salmoides, smallmouth bass Micropterus dolomieu and bluegill sunfish Lepomis macrochirus, in dam reservoirs. The eDNA chip analysis using each IAS-specific primer and probe only amplified and detected the target species. The developed eDNA chip detected three IAS from water samples collected in five dam reservoirs, indicating that eDNA chip analysis can be used as a monitoring tool for IAS. However, IAS were not detected by the eDNA chip at some survey sites where the qPCR assays showed low eDNA concentrations, indicating a lower sensitivity of the eDNA chip at low eDNA concentrations. For the establishment of an eDNA chip for biomonitoring, some challenges faced by other techniques like qPCR and metabarcoding remain, such as sensitivity at low target concentrations and “real-time” detections in the field and further improvement of performance in eDNA chip will be required.