Environmental DNA (eDNA) as a Next-Generation Tool for Biodiversity Monitoring: A Review

Environmental DNA (eDNA) is genetic material released by organisms into water, soil, air, and sediment. It has rapidly become a transformative tool for biodiversity monitoring, enabling the detection of species without physically capturing them. Initially applied primarily in aquatic environments, this non-invasive technology has expanded through metabarcoding techniques to multispecies assessments across freshwater, marine, terrestrial, and aerial ecosystems. This narrative-integrative review synthesises current eDNA science across four dimensions: (1) biological and physicochemical understanding of eDNA production, transport, and degradation; (2) laboratory and bioinformatic approaches for eDNA detection; (3) applications across diverse ecosystems; and (4) uncertainties and limitations affecting the reliability of eDNA-based inferences. A literature search across four bibliographic databases—Web of Science, Scopus, Google Scholar, and PubMed—covering peer-reviewed publications from 2008 to 2024 highlighted the potential of eDNA for identifying endangered and cryptic species, reconstructing historical biodiversity, and monitoring biological invasions. Emerging applications, including airborne eDNA sampling, palaeogenomic reconstruction through sediment analysis, and landscape genomics, are also explored. Challenges in community-level biodiversity characterisation persist because of primer bias, disparities in bioinformatic methodologies, and incomplete reference databases, which introduce uncertainty into data interpretation. Quantitative eDNA monitoring is further constrained by the scarcity of species-specific calibration data, while variation in sampling and analytical protocols limits cross-study comparability. Standardising these methodologies and improving comprehensive reference databases are therefore essential for establishing eDNA as a reliable conservation tool. Overall, eDNA represents one of the most promising and rapidly developing approaches in conservation biology and ecological monitoring.