Distinct latitudinal community patterns of Arctic marine vertebrates along the East Greenlandic coast detected by environmental DNA

Aim: Greenland is one of the places on Earth where the effects of
climate change are most evident. The retreat of sea ice has made East
Greenland more accessible for longer periods during the year. East
Greenland fjords have been notoriously difficult to study due to their
remoteness, dense sea ice conditions and lack of infrastructure. As a
result, biological monitoring across latitudinal gradients is scarce in
East Greenland and relies on sporadic research cruises and trawl data from
commercial vessels. We here aim to investigate the transition in fish and
marine mammal communities from South to Northeast Greenland using
environmental DNA (eDNA). Location: South to Northeast Greenland.
Methods: We investigated the transition in fish and marine mammal
communities from South to Northeast Greenland using eDNA metabarcoding of
seawater samples. We included both surface and mesopelagic samples,
collected over approximately 2400 km waterway distance, by sampling from
Cape Farewell to Ella Island in August 2021. Results: We
demonstrate a clear transition in biological communities from south to
northeast, with detected fish and mammal species matching known
distributions. Samples from the southern areas were dominated by capelin
(Mallotus villotus) and redfish (Sebastes), whereas northeastern samples
were dominated by polar cod (Boreogadus saida), sculpins (Myoxocephalus)
and ringed seal (Pusa hispida). We provide newly generated 12S rRNA
barcodes from 72 fish species, bringing the public DNA database closer to
full taxonomic coverage for Greenlandic fish species for this locus. Main
conclusions: Our results demonstrate that eDNA sampling can
detect latitudinal shifts in marine biological communities of the Arctic
region, which can supplement traditional fish surveys in understanding
species distributions and community compositions of marine vertebrates.
Importantly, sampling of eDNA can be a feasible approach for detecting
northward range expansions in remote areas as climate change progresses.