Data from: The role of taxonomic expertise in interpretation of metabarcoding studies

The performance of DNA metabarcoding approaches for characterizing
biodiversity can be influenced by multiple factors. Here we used
morphological assessment of taxa in zooplankton samples to develop a large
barcode database and to assess the congruence of taxonomic identification
with metabarcoding under different conditions. We analyzed taxonomic
assignment of metabarcoded samples using two genetic markers (COI, 18S
V1-2), two types of clustering into molecular operational taxonomic units
(OTUs, ZOTUs), and three methods for taxonomic assignment (RDP Classifier,
BLASTn to GenBank, BLASTn to a local barcode database). The local database
includes 1042 COI and 1108 18S (SSU) barcode sequences, and we added new
high-quality sequences to GenBank for both markers, including 109
contributions at the species level. The number of phyla detected and the
number of taxa identified to phylum varied between genetic marker and
among the three methods used for taxonomic assignments. Blasting the
metabarcodes to the local database generated multiple unique contributions
to identify OTUs and ZOTUs. We argue that a multi-marker approach combined
with taxonomic expertise to develop a curated, vouchered, local barcode
database increases taxon detection with metabarcoding, and its potential
as a tool for zooplankton biodiversity surveys.