Arctic study of cephalopods and climate change finds a new species
Cephalopods, including squids and octopods, are abundant in the Arctic, as important prey for fishes and top predators, and as predators themselves preying on fishes, crustaceans and other cephalopods. As the Arctic experiences amongst the most pronounced climate change impacts, thanks to their short life cycles and fast generational turnover, cephalopods offer a valuable proxy group for monitoring these impacts. Despite this, Arctic cephalopods remain under-studied. Setting out to address this, the EU-supported ArCeph project has advanced knowledge about the distribution, predator-prey interactions, behaviour and life histories of Arctic cephalopods. Also, for the first time since the 1930s, the team discovered two, and formally described one, new species of Arctic cephalopods. “We found that cephalopods reveal climate change impacts over significant historical timelines! Comparing the ecology of cephalopods in modern, with historical – late 19th and early 20th centuries – times, we found shifts in trophic ecology due to climate-caused ecosystem changes,” explains project coordinator Alexey Golikov, from GEOMAR, the project host.
The biodiversity, life histories and ecological role of cephalopods
The project set out to test three research hypotheses. Firstly, that Arctic cephalopods’ diversity and distribution changed due to climate factors. For this, the team used over 15 years of continuous abundance and biomass sampling from the Norwegian region of the Barents Sea. The addition of taxonomy work on morphological and molecular data resulted in a new cephalopod species being described. Secondly, stable isotope analyses comparing historical and contemporary specimens, tested whether the environmental and trophic conditions (such as diet) experienced by individual cephalopods could infer climate change impacts. Lastly, underwater observations (using PELAGIOS, a towed camera system, and remotely operated vehicles), captured previously unknown behaviour of deep-sea Arctic cephalopods, exploring their role in the Arctic food web. Their trophic interactions are now being computer modelled at GEOMAR. ArCeph showed that both cephalopods’ biomass and abundance in the Barents Sea – the most climate change-impacted Arctic area – and the feeding habits of the most abundant Arctic cephalopod species, altered in the late 1990s/early 2000s. This coincides with when the environmental impact of climate change is known to have increased in the Arctic. The comparative historical study, along with others, showed that species of many taxa (including cephalopods) arrived in the Arctic from boreal to subtropical regions, reflecting climate-driven ecosystem changes. This influx provided a food source for local Arctic squid, which also moved further east to areas previously too cold. Another important finding was the discovery of a new trophic pathway. While dwelling 500–2 600 metres above the seafloor, deep-sea octopods are seafloor feeders. As cephalopods are eaten by apex fishes and toothed whales above the seafloor, so they transfer carbon from the small seafloor benthos to large pelagic top predators. “This behaviour of living in the water column, but eating on the seafloor, was previously unknown in cephalopods,” notes Golikov.
A model organism for tracking climate change in the Arctic
Partly due to their opportunistic predation, enabling nimble adaptation, ArCeph has demonstrated cephalopods to be excellent model organisms for studying the marine ecosystem. And the project’s results offer important inputs for EU Arctic management strategies. “Some areas where the newly discovered cephalopod-driven bentho-pelagic coupling occurs, are partly within and some partly outside, the zone designated for commercial fishing; the same for the areas with newly described cephalopod species and cephalopod hotspots. This has conservation implications for unique but poorly studied marine ecosystems,” adds Golikov. This research was undertaken with the support of the Marie Skłodowska-Curie Actions programme.
Keywords
ArCeph, Arctic, biodiversity, trophic, climate change, cephalopods, ecosystem, species
