View article

Recurrent assessments of freshwater macrozoobenthic diversity are widely applied to monitor stream health. Unfortunately, most taxa are sampled at larval stage and can often not be accurately identified based on morphology. Additionally, identification can be time-consuming. Thus, the approach leads to high assessment costs while providing limited accuracy and resolution. Here, DNA metabarcoding has emerged as a potential solution, but biases of the technique are currently not sufficiently evaluated to allow application in routine assessments. Two main biases of metabarcoding are (i) effects of different taxon biomass in complete bulk samples and (ii) primer bias leading to the over-or underrepresentation of taxa, thus negatively influencing assessment accuracy. Using 10 mock bulk communities each containing 52different freshwater taxa and primer evaluation tools (PrimerMiner) we …