Sources of uncertainty in DNA metabarcoding of whole communities: implications for its use in biomonitoring

These data were derived from a structured experiment to assess factors
influencing the precision and accuracy of molecular methods for freshwater
macroinvertebrate community assessment. Benthic macroinvertebrates were
sorted, identified, and counted from nine individual kick-net samples
using standard morphometric protocols, then reconstituted. These bulk
specimen samples were then homogenised. From each bulk sample, aliquots of
the homogenate were distributed among seven laboratories across Europe for
DNA extraction, PCR amplification, library preparation, and sequencing.
Additionally, each laboratory was provided with a DNA extract from the
bulk homogenate to allow for amplification through to sequencing, in order
to assess the influence of DNA extraction. The data consist of abundances
of individual taxa identified using morphometric protocols and read counts
of operational taxonomic units identified by the molecular methods. In
addition, we provide a taxonomically harmonised matrix of the community
composition derived from morphometric and molecular approaches to
facilitate comparison between the two methods.