Résumé
Environmental DNA (eDNA) has the potential to provide more comprehensive
biodiversity assessments particularly for vertebrates in species-rich
regions. Yet, this method requires the completeness of a reference
database, i.e. a list of DNA sequences attached to each species, which is
never met. As an alternative, a diversity of Operational Taxonomic Units
(OTUs) can be extracted from eDNA metabarcoding. However, the extent to
which the diversity of OTUs provided by a limited eDNA sampling effort can
predict regional species diversity is unknown. Here, by modelling OTU
accumulation curves of eDNA seawater samples across the Coral Triangle, we
obtained an asymptote reaching 1,531 fish OTUs while 1,611 fish species
are recorded in the region. Besides, we also accurately predict (R² =
0.92) the distribution of species richness among fish families from
OTU-based asymptotes. Thus, the multi-model framework of OTU accumulation
curves extends the use of eDNA metabarcoding in ecology, biogeography and
conservation.