Arctic nekton uncovered by eDNA metabarcoding: diversity, potential range expansions and benthopelagic coupling

The Arctic Ocean is home to a unique fauna that is disproportionately
affected by global warming but that remains under-studied. Due to their
high mobility and responsiveness to global warming, cephalopods and fishes
are good indicators of the reshuffling of Arctic communities. Here, we
established a nekton biodiversity baseline for the Fram Strait, the only
deep connection between the North Atlantic and Arctic Ocean. Using
universal primers for fishes (12S) and cephalopods (18S), we amplified
environmental DNA (eDNA) from seawater (50–2700 m) and deep-sea sediment
samples collected at the LTER HAUSGARTEN observatory. We detected twelve
cephalopod and 31 fish taxa in the seawater and seven cephalopod and 28
fish taxa in the sediment, including the elusive Greenland shark
(Somniosus microcephalus). Our data suggest three fish (Mallotus villosus,
Thunnus sp. and Micromesistius poutassou) and one squid (Histioteuthis
sp.) range expansions. The detection of eDNA of pelagic origin in the
sediment also suggests that M. villosus, Arctozenus risso and M. poutassou
as well as gonatid squids are potential contributors to the carbon flux.
Continuous nekton monitoring is needed to understand the ecosystem impacts
of rapid warming in the Arctic and eDNA proves to be a suitable tool for
this endeavor.