DISCUSSION
Our focus on well characterised macrobenthic communities from the North
sea allowed to investigate and understand the biases inherent to DNA
metabarcoding when characterising macrobenthic diversity. We found
considerable differences in alpha and beta diversity patterns between
the tested primer sets and between the two sample types (bulk DNA vs
eDNA from the ethanol preservative) and show that the detection of
macrobenthic species in the eDNA of the ethanol preservative is linked
to their body size and body skeleton. In addition, the one to one
comparison between morphology based identification and DNA metabarcoding
of bulk DNA and eDNA from the ethanol preservative and the availability
of a nearly complete reference database shows that discrepancies between
morpho-taxonomic and DNA metabarcode datasets are not entirely the
result of incomplete reference databases.