Benthic eDNA metabarcoding provides accurate assessments of impact from
oil extraction, and ecological insights
Abstract
Apart from its contribution to climate change, offshore oil and gas
extraction is also a potential threat to the diversity and function of
marine ecosystems. Routine monitoring of the environmental status of
affected areas is therefore critical for proper management. While
current morphology-based monitoring is relatively time-consuming, costly
and prone to identification bias, environmental DNA metabarcoding offers
an attractive alternative, including for impacts of oil drilling,
extraction or spills. However, to be ready for routine monitoring, its
performance needs to be demonstrated, through agreement with assessments
based on physicochemical measurements and current bioindicators. To this
end, we applied metabarcoding to sequence the metazoan and total
eukaryotic benthic components. We targeted an range of sites, from high
to low impacts, located near active production platforms and reference
sites, in the North and Barents Seas. Alpha diversity and community
structure of both datasets correlated strongly with a physicochemical
pressure index (PI), based on total hydrocarbons, PAH16, Ba and Cu. The
macroinvertebrate-based Norwegian Sensitivity Index (NSI) based on the
COI metabarcoding data also agreed well with morpho-taxonomy based
values, and with PI. Further, we identified a set of bioindicator taxa
from both metabarcoding datasets, to develop novel biotic indices and
demonstrate their predictive performance using cross-validation.
Finally, we compared co-occurrence networks from impacted v less
disturbed sites, to improve the understanding of the ecological
consequences of impacts. Our study demonstrates that metabarcoding is
comparable to the morpho-taxonomic approach in terms of accuracy, and
could eventually be used to replace it, given further efforts.