Article ID: 25-00011
Environmental DNA (eDNA) analysis, now an indispensable tool for monitoring macro-organisms, was first reported to be performed on microorganisms in 1987 and subsequently used to analyze ancient DNA. In 2008, Ficetola et al. successfully detected bullfrog DNA in water, revolutionized the monitoring of macro-organisms. Japanese researchers independently started eDNA studies and have achieved many important results. Of note are the work on eDNA quantification by Takahara et al. and the development of the fish eDNA metabarcoding primer "MiFish" by Miya et al. Environmental DNA analysis is particularly effective for large-scale monitoring because it is easy to perform in the field and does not require expertise. In Japan, multiple large scale surveys have been conducted, and a large amount of data has been accumulated. Early eDNA sudies mainly targeted eDNA in water, but in recent years, efforts have been made to extract DNA from various media, including underwater sediments and surfaces of plants. Applications to the monitoring of infectious diseases and the spatiotemporal understanding of the reproductive behavior of organisms are also in progress. These applications are expected to be useful in the prevention and control of infectious diseases and in the conservation of rare organisms. However, there are several challenges in eDNA analysis. The biggest challenge is the richness and accuracy of the reference DNA sequence database, and the uncertainty of the spatiotemporal range exhibited by eDNA is also a major issue. Environmental DNA analysis is still a young technology that requires further development. We must also remember that eDNA analysis is not a substitute for physical sampling and that the fundamentals of biological monitoring should not be neglected. Conveying the richness of ecosystems to the next generation is also crucial for nature conservation.
