Conserving freshwater biodiversity: The value, status and management of high quality ditch systems

Freshwater biodiversity is globally threatened and while most conservation efforts are focussed on natural and larger freshwater systems such as rivers and lakes, in many lowland agricultural landscapes artificial water bodies including ditches may be equally important as habitats for freshwater species. Ditches occur across the agricultural landscape but in particular, those associated with coastal and floodplain grazing marsh, have high conservation value. The importance of this habitat for rare and threatened species afforded priority status under the UK Biodiversity Action Plan is explored. The characteristics of ditches that have high conservation value are described and a set of targets against which such ditches can be assessed are presented. An analysis of the current condition of Sites of Special Scientific Interest (SSSI) for the wider coastal and floodplain grazing marsh habitat demonstrates the range of pressures affecting these sites and highlights that alongside generic freshwater issues such as eutrophication and non-native species, these sites have a unique set of pressures associated with their ongoing management and the vulnerable location of many sites at the coast. Wider conservation strategies for freshwater biodiversity in lowland landscapes across Europe need to factor in the different management requirements of artificial habitats such as ditches alongside more ambitious restoration projects for natural waterbodies. In low lying coastal areas the threat of coastal squeeze for many important grazing marshes will require a strategic approach to allow upstream migration of important biodiversity.