Established in 1988, the UK Upland Waters Monitoring Network (UKUWMN) was initiated by the UK Government to monitor the effects of emission control legislation on the water chemistry and biodiversity of 22 lakes and streams across the UK. Since monitoring commenced, the water chemistry of most sites has shown clear signs of recovery (e.g. rising pH and declining labile aluminium concentrations). Aquatic plants are a key component of freshwater biodiversity, but their response to changes in water acidity have received much less attention than other biological groups such as fish or macroinvertebrates. Project-specific standardised plant survey methodologies have been used throughout the time-series, and these have been augmented by Water Framework Directive Common Standards Monitoring Methodology survey techniques at lake sites since 2009, and at stream sites since 2019. The current study aims to determine the extent to which these stream and lake plant communities may have responded to regional reductions in aquatic acidity and to what degree any recovery may be confounded by other drivers such as climate-related changes in water temperature, hydrology, flow and storminess, hydromorphology and additionally the changing light climate/ice cover environment in lakes. A second aim is to examine the preservation and scientific potential of plant DNA in lakes for reconstructing past aquatic plant assemblages by comparing the current water sample eDNA, annual sediment trap sedDNA and sediment core sedDNA records with the known biomonitoring records
