Biological intercalibration: Invertebrates 2018

The 22nd biological intercalibration of invertebrates in the ICP Waters programme included four laboratories. The intercalibration is important for harmonising taxonomic work across countries, and is of high value in programmes where the focus is on community analyses, e.g. for the classification of ecological status according to the EU Water Framework Directive. The laboratories correctly identified 96 % of the species and 97% of the genera. The mean Quality assurance index ranged between 85 and 99. No laboratories had a mean value below 80 – the limit for acceptable taxonomic work. Trends in biological intercalibration of invertebrates from the initial intercalibration in 1992 to 2018 are presented, showing that the Qi has remained above 80% for the full period, suggesting skilled taxonomists in the laboratories affiliated to ICP Waters. For individual invertebrate groups, the laboratories perform best for caddis flies and worst for stoneflies. The Quality assurance index increased steadily during the first 22 years and has seemingly decreased during the last three years, possibly because of an increase in difficulty.