Even more Chironomid species for classifying lake nutrient status

Abstract

The European Union Water Framework Directive (WFD) classifies ecological status of a waterbody by the determination of its natural reference state to provide a measure of perturbation by human impacts based on taxonomic composition and abundance of aquatic species. Ruse (2010;2011) has provided methods of assessing anthropogenic perturbations to lake ecological status, in terms of nutrient enrichment and acidification, by analysing collections of floating pupal exuviae discarded by emerging adult Chironomidae. The previous nutrient assessment method was derived from chironomid and environmental data collected during 178 lake surveys of all WFD types found in Britain. Canonical Correspondence Analysis provided species optima in relation to phosphate and nitrogen concentrations. Species found in less than three surveys were excluded from analysis in case of spurious association with environmental values. Since Ruse (2010) an additional 72 lakes have been surveyed adding 31 more species for use in nutrient status assessment. These additional scoring species are reported here. The practical application of the Chironomid Pupal Exuvial Technique (CPET) to classify WFD lake nutrient status is demonstrated using CPET survey data from lakes in Poland.