Ecological monitoring on two rivers in South Wales: Fish Surveys, Macroinvertebrate Sampling and Flow Monitoring.
Walkover surveys were undertaken to identify suitable monitoring sites and highlight any issues in terms of health and safety, access or landowner permissions. Sites were chosen to ensure the safety of operatives whilst providing the level of robust data required to assess the impacts of a number of discharges (e.g. ensuring spatial extent and up and downstream monitoring locations at discharges).
Standard 3 minute macroinvertebrate kick net surveys were undertaken at a number of sites on both rivers in spring and autumn 2019 including control sites on unimpacted reaches. Macroinvertebrate samples were analysed to species level (TL5) and data outputs included WHPT, NTaxa, ASPT, CCI, LIFE (Family), LIFE (Species), PSI and RICT indices.
Fully quantitative electric fishing surveys were undertaken at all sites concurrently with autumn macroinvertebrate sampling to reduce costs. A combination of backpack and generator-based electric fishing equipment was used according to the channel width at each site and three runs were undertaken over a 100m section between stop nets at all sites.
Spot flow gauging of wetted width, depths and velocities was undertaken at one location on each river on a significant number of occasions over a three-month period. Depths and flow velocities were measured across the cross-sections in line with BS ISO 748:2007, using a measuring staff and calibrated Valeport 801 (Flat Type) EM Flow Meter. Flow monitoring was undertaken under as full a range of flow conditions as possible to adequately calibrate the modelled flow duration curve. As many visits as possible were undertaken during other fieldwork e.g. fish surveys to reduce costs.
Monitoring confirmed that protected fish species were present within the impacted reaches of the two rivers. Atlantic salmon Salmo salar, juvenile lamprey and European eel Anguilla anguilla were all recorded. In addition, migratory sea trout Salmo trutta and the estuarine migrant flounder Platichthys flesus were also recorded in lower sites highlighting that potential impacts on SAC habitats and populations downstream may need to be considered in any assessment.
Significant cost savings were possible thanks to Five Rivers’ ability to deploy skilled multidisciplinary teams and combine a range of ecological and environmental monitoring.