linking the presence of invasive alien species to measure ecological quality

The Water Framework Directive (WFD) is European Union (EU) legislation which aims for 'good status' for all ground and surface waters in the EU. The ecological and chemical status of surface waters is assessed on four criteria including, Biological Quality (fish, benthic invertebrates, aquatic flora). Biological invasions are increasing and are widely acknowledged to threaten bio-diversity. Although this general principle is not disputed we cannot currently produce the evidence that the presence of invasive species...