• Energy Research

Climate change is threatening marine ecosystems on a global scale but particularly so in the Arctic. As a result of warming, species are shifting their distributions, altering marine communities and predator-prey interactions. This is known as the Atlantification of the Arctic. Warming may favor short-lived, opportunistic species such as cephalopods, marine mollusks that previously have been hypothesized to be winners in an ocean of change. To detect temporal regional trends in biodiversity, long-term annual surveys in hotspots of climate change are an unparalleled source of data. Here, we use 18 years of annual bottom trawl data (2005–2022) to analyse cephalopods in the western Barents Sea. More specifically, our research goals are to assess temporal trends in cephalopod fauna composition, abundance and biomass, and to relate these trends to climate change in the western Barents Sea. Main changes in cephalopod diversity and distribution occurred in mid-2000s and early 2010s, which corresponds with a period of warming in the Arctic since the late 1990s/early 2000s. Repeated increased occurrence of the boreal-subtropical cephalopods was recorded from 2005–2013 to 2014–2022. Moreover, the abundance of cephalopods in the area (in general and for most taxa) increased from 2005–2013 to 2014–2022. These observations suggest that the cephalopod community of the Barents Sea is subjected to Atlantification since the 2005–2013 period. This corresponds with previously reported evidence of the Atlantification in fishes and benthic invertebrates in the Barents Sea and benthic invertebrates. ‘Typical’ Arctic cephalopod species such as Bathypolypus spp., Gonatus fabricii and Rossia spp., however, are still much more abundant in the western Barents Sea compared to the deep-sea and the boreal-subtropical species. We also found indirect indications for body-size reduction in Bathypolypus spp. from 2005–2013 to 2014–2022. Overall, the temporal trends in the Barents Sea cephalopod fauna provide evidence for changing marine communities in the Arctic.

AbstractVampyroteuthis infernalis Chun, 1903, is a widely distributed deepwater cephalopod with unique morphology and phylogenetic position. We assessed its habitat and trophic ecology on a global scale via stable isotope analyses of a unique collection of beaks from 104 specimens from the Atlantic, Pacific and Indian Oceans. Cephalopods typically are active predators occupying a high trophic level (TL) and exhibit an ontogenetic increase in δ15N and TL. Our results, presenting the first global comparison for a deep-sea invertebrate, demonstrate that V. infernalis has an ontogenetic decrease in δ15N and TL, coupled with niche broadening. Juveniles are mobile zooplanktivores, while larger Vampyroteuthis are slow-swimming opportunistic consumers and ingest particulate organic matter. Vampyroteuthis infernalis occupies the same TL (3.0–4.3) over its global range and has a unique niche in deep-sea ecosystems. These traits have enabled the success and abundance of this relict species inhabiting the largest ecological realm on the planet.

The high Arctic shelves are the particularly understudied area of the Arctic. Climate change is predicted to cause increase in primary production with cascading effect on the Arctic ecosystems, and predicted increased ship traffic through the now-ice-free areas will create anthropogenic disturbance. Thus, understanding the high Arctic shelves is required. The cephalopods are ecologically important in the area, but severely understudied. We use recent samples (2014–2019) and reuse existing literature data (1901–1998) from the Siberian and Canadian high Arctic shelves to assess distribution and ecology of cephalopods. The fauna composition of these shelves is similar, and includes two benthic octopods and two nekto-benthic bobtail squids, and two more species over the adjacent slopes. Distribution limits are updated for all shelf species, and associated environmental parameters allow for better understanding of their realised niches. The reproduction of studied cephalopods occurs from July to November, and the hatching period throughout the summer. Crustaceans are their main prey, but several more taxa are found in the stomach contents. The prey sizes range from ∼7% to ˃100% of the respective cephalopod size. Climate-driven changes in predator and prey composition are predicted to be the main drivers of the future climate change impact on cephalopods over the high Arctic shelves.

Abstract Background Assessing the historical dynamics of key food web components is crucial to understand how climate change impacts the structure of Arctic marine ecosystems. Most retrospective stable isotopic studies to date assessed potential ecosystem shifts in the Arctic using vertebrate top predators and filter-feeding invertebrates as proxies. However, due to long life histories and specific ecologies, ecosystem shifts are not always detectable when using these taxa. Moreover, there are currently no retrospective stable isotopic studies on various other ecological and taxonomic groups of Arctic biota. To test whether climate-driven shifts in marine ecosystems are reflected in the ecology of short-living mesopredators, ontogenetic changes in stable isotope signatures in chitinous hard body structures were analysed in two abundant squids (Gonatus fabricii and Todarodes sagittatus) from the low latitude Arctic and adjacent waters, collected between 1844 and 2023. Results We detected a temporal increase in diet and habitat-use generalism (= opportunistic choice rather than specialization), trophic position and niche width in G. fabricii from the low latitude Arctic waters. These shifts in trophic ecology matched with the Atlantification of the Arctic ecosystems, which includes increased generalization of food webs and higher primary production, and the influx of boreal species from the North Atlantic as a result of climate change. The Atlantification is especially marked since the late 1990s/early 2000s. The temporal patterns we found in G. fabricii’s trophic ecology were largely unreported in previous Arctic retrospective isotopic ecology studies. Accordingly, T. sagittatus that occur nowadays in the high latitude North Atlantic have a more generalist diet than in the XIXth century. Conclusions Our results suggest that abundant opportunistic mesopredators with short life cycles (such as squids) are good candidates for retrospective ecology studies in the marine ecosystems, and to identify ecosystem shifts driven by climate change. Enhanced generalization of Arctic food webs is reflected in increased diet generalism and niche width in squids, while increased abundance of boreal piscivorous fishes is reflected in squids’ increased trophic position. These findings support opportunism and adaptability in squids, which renders them as potential winners of short-term shifts in Arctic ecosystems.

Gonatus fabricii (Gonatidae)Time series; Year; n squids; Area; SourceLate XIXth C.; 1882; 1; Baffin Bay; BycatchLate XIXth C.; 1891; 1; ---; ---;1990s; 1900; 9; Nordic Seas; Northern fulmar's stomach contents1930s; 1930; 2; Davis Strait; Sleeper shark's stomach contents1930s; 1936; 5; Baffin Bay; Bycatch1970s; 1975; 5; ---; Bycatch1970s; 1977; 2; ---; Bycatch1970s; 1979; 2; ---; Bycatch2000s; 2004; 10; ---; Bycatch2010s; 2010; 10; Nordic Seas; Sperm whale's stomach contentsTodarodes sagittatus1840s; 1844; 4; Faroe Islands; Long-finned pilot whale's stomach contents1880s; 1881; 10; Iceland; Long-finned pilot whale's stomach contents1890s; 1897; 10; Faroe Islands; Long-finned pilot whale's stomach contentsContemporary 2016; 1; Ireland; BycatchContemporary; 2017; 1; Ireland; BycatchContemporary; 2018; 1; Ireland; BycatchContemporary; 2023; 4; Ireland; Bycatch Raw data obtained from stable isotope analysis of δ13C and δ15N in beaks of the squids Gonatus fabricii (Lichtenstein, 1818) and Todarodes sagittatus (Lamarck, 1798) (Cephalopoda: Oegopsida), and primary analyses of these data. Squids sampled in the Baffin Bay, Davis Strait and Nordic Seas (1882-2010) and Iceland, Faroe Islands and Ireland (1844-2023), respectively. The beaks either come from the squids caught as bycatch, or from natural history museums, from stomach contents of predators.

AbstractTrophic niche and diet comparisons among closely sympatric marine species are important to understand complex food webs, particularly in regions most affected by climate change. Using stable isotope analyses, all ontogenetic stages of three sympatric species of Arctic cephalopods (genusRossia) were studied to assess inter- and intraspecific competition with niche and diet overlap and partitioning in West Greenland and the Barents Sea. Seven traits related to resource and habitat utilization were identified inRossia: no trait was shared by all three species. High borealR. megapteraand Arctic endemicR. moellerishared three traits with each other, while bothR. megapteraandR. moellerishared only two unique traits each with widespread boreal-ArcticR. palpebrosa. Thus all traits formed fully uncrossing pattern with each species having unique strategy of resource and habitat utilization. Predicted climate changes in the Arctic would have an impact on competition amongRossiawith one potential ‘winner’ (R. megapterain the Barents Sea) but no potential ‘losers’.