From subterranean blues to stygofauna clues: Developing a groundwater ecology monitoring network for England

With growing recognition of groundwater as an important ecosystem, it is increasingly clear that current monitoring, focused predominantly on water quantity and quality, does not capture its ecological value. This paper describes the design, implementation and initial findings of the first national-scale groundwater ecology monitoring network in England. The network was established in 2024 and uses a hydrogeological typology, comprising 11 geo-habitats grouped into three habitat quality categories (high, moderate and low). Utilising existing groundwater monitoring infrastructure, groundwater fauna (stygofauna) and physicochemical parameters were sampled at 81 locations. Current findings indicate that stygofauna are widely distributed, but with contrasting patterns observed for facultatives (stygophiles) and obligates (stygobites). Nearly all known stygobitic taxa in England were recorded in network samples, along with new location records and the rediscovery of a species not recorded nationally for almost a century. Binomial generalised linear models indicated that site location significantly influenced stygobite occurrence, whilst repeated sampling marginally increased the probability of detecting stygobites. For stygophile occurrence was negatively associated with the depth of water within a borehole/well. Habitat quality category and other physicochemical parameters had no detectable influence on faunal presence. The establishment of this network represents a major step towards incorporating biological metrics into groundwater assessment. As temporal coverage increases and additional indicators are incorporated the network will provide robust evidence for evaluating groundwater ecosystem functioning and ecological status.