Identifying the source of anthropic pressures on in-stream benthic algae communities within the River Eden catchment, UK

Declines in riverine biodiversity are impacted by catchment connectivity to potential nutrient sources.  Many studies have focused on biodiversity as a direct expression of instream attributes, thus neglecting the critical role of catchment connectivity to the river network as key determinants of biodiversity. To protect and restore the ecological integrity and wider ecosystem function of riverine systems, the spatial connectivity of the stream networks to their catchments must be considered in mitigation measures. Given their extent and high connectivity with the surrounding landscape, low-order streams are particularly vulnerable to land-use pressures and demonstrate high sensitivity to nutrients (N and P), impacting the composition and seasonally persistence of benthic algal communities.

Here, we utilise the Sensitive Catchment Integrated Mapping Analysis Platform (SCIMAP) to explore the spatial risk to land-use-driven nutrient pollutant pressures across the River Eden (NW England) catchment.Our results show that the potential source areas for the examined pollutants are in specific locations in the catchment. Therefore, the most effective locations for management measures will differ for different pollutant or ecological endpoints.  This means that the Programme of Measures under the Water Framework Directive requires the integration of multiple lines of ecological evidence at the appropriate spatiotemporal scales. We demonstrate that this approach can guide prediction on instream ecological status and identify spatial sources, thus providing a more quantitatively transparent and accurate risk assessment for catchment management and mitigation