SCANDNAnet — validating and intercalibrating metabarcoding for routine use in Nordic freshwater biomonitoring

Background: DNA metabarcoding holds great capacity for the assess- ment of macroinvertebrates in aquatic ecosystems. However, few large-scale studies have compared the performance of DNA metabar- coding with that of routine morphological identification. We will me- tabarcode several hundred macroinvertebrate samples from stream and lake sites across Denmark, Finland, Iceland, Norway, and Sweden. The samples were collected in 2017 and 2018 using national sampling protocols. Specimens were identified by morphology, following stan- dardised protocols used in the routine national monitoring programs. Results: Our preliminary results presented at the conference will likely show that DNA metabarcoding identifies more than twice the number of taxa compared with the morphology-based protocol, and yield a higher taxonomic resolution. We will calculate and compare the ecological status assessment metrics from morphological and DNA metabarcoding datasets. Significance: We show that DNA me- tabarcoding is applicable in routine national monitoring programs at large scale. DNA metabarcoding represents a feasible and reliable method to identify macroinvertebrates in aquatic bioassessments and offers powerful advantages over morphological identification in pro- viding identification for taxonomic groups that are unfeasible to iden- tify in routine protocols.