Global eDNA Initiative Aims to Unlock the Hidden Biodiversity of Groundwater

Beneath the Earth’s surface lies the planet’s largest reservoir of unfrozen freshwater, a vast and largely unexplored realm that sustains some of the most specialized and ancient lineages in the tree of life. Groundwater ecosystems, populated by relictual species found nowhere else, not only harbor remarkable taxonomic, functional, and phylogenetic diversity but also play a crucial role in sustaining the global water cycle. Yet despite their ecological significance, these subterranean environments remain largely absent from policy frameworks and are overlooked by major conservation initiatives such as the European Water Framework Directive. Now, a new international research initiative called GReG—Global Research on eDNA in Groundwaters—aims to change that by harnessing the power of environmental DNA to reveal and protect the hidden biodiversity of the world’s aquifers.

The initiative was first proposed during the 26th International Conference on Subterranean Biology, held in Sardinia in September 2024. Nine months later, on June 5, 2025, GReG was formally launched through an online seminar led by Dr. Mattia Saccò, Dr. Michelle Guzik, and Dr. Kathryn Korbel. The event brought together 56 representative researchers and regulators from across the globe, marking the beginning of what organizers hope will become a unifying platform for advancing groundwater science through environmental DNA and genomics. The launch seminar featured guest speakers who shared insights from large-scale eDNA studies in oceans, discussed open and FAIR data practices for sharing eDNA information, explored taxon-free eDNA approaches in groundwater research, and examined how eDNA can be deployed to address global biodiversity targets.

Environmental DNA, broadly defined as the total pool of DNA isolated from environmental samples such as water or sediment, has emerged as a transformative tool for biodiversity assessment. By analyzing genetic material shed by organisms into their surroundings, researchers can detect species presence without directly observing or capturing them. The technique has proven successful at unveiling biodiversity patterns from regional to global scales and has been applied in taxonomy-free and functional approaches that bypass the need for traditional morphological identification. eDNA is also increasingly being combined with other large-scale monitoring tools, including satellite data and broader biodiversity datasets, to advance a rich and diverse research agenda across aquatic ecosystems.

In groundwater environments specifically, eDNA research is gaining momentum, with recent studies demonstrating its potential to characterize subterranean communities. However, the field lags behind other biomes such as oceans and rivers in terms of protocol validation, practical application, and the development of DNA assays tailored to subterranean conditions. This gap reflects the broader neglect of groundwater ecosystems in research and conservation, where many calls for action have gone unheeded. Groundwater species face escalating cumulative threats including climate change, land use change, contamination, over-extraction, heating, and salinization, among many others. Left unaddressed, these pressures compromise not only biodiversity but also the vast array of ecosystem services that groundwater environments quietly provide to both nature and human society.

GReG is conceived as a two-phase project designed to disrupt the current inertia in global groundwater conservation. Phase 1, running from June 2025 to June 2026, will involve fieldwork at more than 50 well-known sites across four continents, encompassing karst systems, alluvial aquifers, and anchialine caves. Researchers will apply standardized sampling and analytical protocols targeting biodiversity across the entire Tree of Life, ensuring that results are comparable across sites and regions. In parallel, a survey on methodological approaches in groundwater eDNA research has been circulated to all collaborators, aimed at understanding current practices and identifying limitations for eDNA analysis in groundwater environments. Further projected outputs include peer-reviewed papers on groundwater eDNA protocols and publicly available DNA barcode quality assessments for stygofauna, the specialized animals that inhabit groundwater.

Phase 2, beginning in July 2026, will build on the lessons learned during the first phase to expand the project to the Global South and other under-investigated areas of the world through participatory science approaches. The initiative’s organizers have issued a public call to researchers and stakeholders from these regions, with the ambition of widening novel groundwater-based research beyond well-known global biodiversity hotspots. The collaborative effort is supported by partners including Biodiversa+ projects such as DarCO and Sub-BioMon, research laboratories including the TrEnD Lab at Curtin University and the Altermatt Lab, and global datasets such as Stygofauna Mundi, which catalogues the diversity of groundwater fauna worldwide.

The outcomes of this collaborative effort are expected to include scientific publications, data sharing following FAIR principles—ensuring that findings are Findable, Accessible, Interoperable, and Reusable—workshops, and media articles, all with the objective of advancing subterranean aquatic eDNA research. Beyond the scientific outputs, GReG also aims to raise awareness about the importance of groundwater ecosystems, a notoriously difficult task for environments that remain out of sight and out of mind for most of the public and policymakers alike. By bringing together researchers, regulators, industry stakeholders, and citizens, the initiative seeks to build the interdisciplinary and inclusive coalition needed to translate scientific knowledge into effective conservation action.

The development of conservation strategies for groundwater and groundwater-dependent ecosystems—those that rely on groundwater for some or all of their water needs—requires an improved understanding of subterranean ecological dynamics, particularly under ongoing climatic changes. Current global knowledge on groundwater biodiversity and ecological dynamics remains far from complete, hindering effective assessment and conservation efforts. GReG’s founders argue that the key to preserving unique subterranean biota while using groundwater resources sustainably is not yet lost; what is needed is the right team of researchers, regulators, stakeholders, and citizens working together to develop the biomonitoring tools and conservation guidelines that these hidden ecosystems urgently require.

As the first coordinated global effort to apply eDNA across groundwater ecosystems, GReG represents an ambitious but vital step toward securing the future of the planet’s least visible biodiversity. Its success will depend on sustained collaboration across continents, disciplines, and sectors, and on the willingness of the scientific community and policymakers to finally give groundwater the attention it has long been denied. For an environment that supplies a substantial share of the world’s drinking water and supports irreplaceable evolutionary heritage, the stakes could hardly be higher.

Subject of Research: Environmental DNA-based global research initiative for groundwater biodiversity conservation

Article Title: Advancing subterranean conservation through Global Research on eDNA in Groundwaters (GReG)

Article References: Saccò, M., Elmasri, A., Tawal, M., Alther, R., Altermatt, F., Martínez, A., Mammola, S., Zagmajster, M., Saenz-Agudelo, P., Takahashi, M., Thornhill, J., Andouche, A., Baratti, M., Bilal, M., Bilandžija, H., Bolpagni, R., Boulamail, S., Celico, F., Chauveau, C. A., … Guzik, M. T. (2025). Advancing subterranean conservation through Global Research on eDNA in Groundwaters (GReG). Subterranean Biology, 53, 31-40. https://doi.org/10.3897/subtbiol.53.165710

Image Credits: AI Generated

DOI: 10.3897/subtbiol.53.165710

Keywords: environmental DNA, groundwater, subterranean biodiversity, eDNA, conservation, stygofauna, aquifers, GReG, karst, anchialine caves, FAIR data, Global South