Biological intercalibration: Invertebrates 2019

Abstract

Two laboratories participated in the 23rd biological intercalibration of invertebrates in the ICP Waters programme. The intercalibration is important for harmonising taxonomic work across countries and is of high value 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 a high proportion of the specimens in the test samples. In total, 97 % of the species and 98 % of the genera were correctly identified. With a mean Quality assurance index (Qi) of 92 and 98, the laboratories performed well above the threshold for acceptable taxonomic work (Qi 80). Trends in the biological intercalibration over time indicate that an average of five laboratories have participated. The results show that the mean Qi has remained above 80% for the full period, suggesting skilled taxonomists in the laboratories affiliated to ICP Waters. When the Qi is broken into invertebrate groups, the laboratories, on average, perform best for caddis flies and worst for stoneflies. The mean Qi decreased steeply in 2015-2017. According to the taxonomists that participate, this may be mostly due to an increase in difficulty. The quality has increased since 2017 while the difficulty remains high.