Nature based measures increase freshwater biodiversity in agricultural catchments

Abstract

This is the first study that describes the effect of adding mitigation measures on the freshwater biodiversity of all waterbody types in agricultural catchments. We measured alpha (site) and gamma (catchment) richness annually over a nine-year period in all the streams, ponds and ditches in three upper-catchments in the English lowlands, and investigated whether freshwater plant biodiversity could be increased by adding: (i) multi-functional ecosystem services measures to intercept pollutants, store water and promote biodiversity, and, (ii) biodiversity-only protection measures. In the absence of measures, all catchments saw a decline in macrophyte richness during the survey (mean species loss of 1% pa, rare species loss of 2% pa). Ponds were a key habitat with a disproportionate influence on catchment trends. Five years after introducing measures, natural colonisation of ecosystem services waterbodies (dammed streams and ditches, runoff ponds, flood storage ponds) largely cancelled-out the background loss of plant species but, importantly, did not restore the loss of rare plants. Adding clean water ponds as a biodiversity-only enhancement measure brought substantial benefits: increasing total-catchment richness by 26%, and the number of rare plant species by 181%. Populations of spatially restricted species also increased. Adding stream debris-dams as a biodiversity measure did not affect plant richness or rarity. The findings suggest that ecosystem services measures could bring some biodiversity benefits to agricultural catchments. However, creating clean-water ponds specifically targeted for biodiversity could hold considerable potential as a tool to help stem, and even reverse, ongoing declines in freshwater plant biodiversity across farming landscapes.

Artificial agri‐environment scheme ponds do not replicate natural environments despite higher aquatic and terrestrial invertebrate richness and abundance

“…In an attempt to recreate lost freshwater habitats, artificially created AES ponds are constructed on farmland throughout Europe each year as analogues of natural ponds; now largely restricted to adjacent non‐agricultural habitats (Batáry et al, 2015). Artificial ponds play an important role in metapopulation dynamics, serving as steppingstones for dispersal (Casas et al, 2012) and can sustain an important fraction of regional aquatic diversity, making a significant contribution to freshwater biodiversity (Oertli, 2018; Ruggiero, Céréghino, Figuerola, Marty, & Angélibert, 2008; Williams et al., 2020) and benefiting non‐aquatic species such as bats by providing foraging habitats (Sirami, Jacobs, & Cumming, 2003). However, little is known about the degree to which artificial ponds replicate the biotic and abiotic environments of natural ponds and, therefore, their contribution to habitat and landscape restoration.…”

Detecting Climate Driven Changes in Chlorophyll-a Using High Frequency Monitoring: The Impact of the 2019 European Heatwave in Three Contrasting Aquatic Systems

“…An additional example of a practical use of this approach is that catchment and lake managers could mark the period between the end of a heatwave and arrival of a storm as a nutrient sensitive period, whereby nutrient addition to agricultural lands is restricted which can reduce nutrient export under scenarios where rainfall in not very intense [ 85 ]. In addition, the construction of ponds to intercept such runoff from agricultural land is also a beneficial solution [ 86 ].…”

Opportunities, approaches and challenges to the engagement of citizens in filling small water body data gaps

“…Experienced surveyors can rapidly collect large wetland plant-based datasets, which are extremely cost-effective and have been used to demonstrate important landscape management results (e.g. Williams et al, 2004 , 2020 ). In terms of amphibians, there is a substantial cadre of surveyors able to recognise the organisms and the main challenge is organising volunteers into effective surveys.…”