The arctic ocean is changing rapidly
The addition of new southerly species and loss of Arctic ones impact Arctic biodiversity and ecosystem organization. The impact of climate change on Arctic marine ecosystems is well documented in the Barents Sea. Here, climate-driven Atlantification, whereby Arctic waters characteristics, such as temperature and salinity, become increasingly similar to Atlantic ones, has progressed very rapidly in recent years.
Atlantification promotes pelagic production, which benefits many boreal species feeding on pelagic prey. In contrast, Arctic species are often reliant on prey associated with sea-ice, which is being lost, or sea bottom. Such differences in habitat and diet use between boreal and Arctic species illustrate important biogeographic distinctions in functional characteristics that influence the role played by species in the ecosystem.
The borealization of Arctic biodiversity triggered by warming thus leads to an ecosystem reorganization. The pelagic compartment becomes increasingly important, and incoming boreal species such as cod, with broad diets including many Arctic species, tend to connect previously distinct components of the Arctic food web. The rapid change in Arctic marine biodiversity and ecosystem organization is accelerated by extreme climatic events, such as heat waves, that are becoming more frequent and intense due to climate warming.
In the Barents Sea, there were three such events since 2006, with record breaking high temperatures and low sea-ice cover. Each event was associated with substantial redistributions of fish species, and was followed by only partial recoveries, leading to a cumulative effect that magnifies the impact of gradual warming.
Climate warming increases the risk of local extinction of Arctic species directly, by changing their physical environment, and indirectly by favoring their boreal predators and competitors. To be sustainable, the rapidly developing human activities in the Arctic must account for the impact of climate warming in the cumulative risk to Arctic marine biodiversity.
Ingvaldsen RB, Assman KM, Primicerio R, Fossheim M, Polyakov IV, Dolgov AV 2021. Physical manifestations and ecological implications of Arctic Atlantification. Nature Reviews Earth and Environment 2: 874–889. doi: 10.1038/s43017-021-00228-x
Pecuchet L, Blanchet M-A, Frainer A, Husson B, Jørgensen LL, Kortsch S, Primicerio R. 2020. Novel feeding interactions amplify the impact of species redistribution on an Arctic food web. Global Change Biology 26: 4894-4906. doi: 10.1111/gcb.15196
Husson B, Lind S, Fossheim M, Kato-Solvang H, Skern-Mauritzen M, Pécuchet L, Ingvaldsen RB, Dolgov AV, Primicerio R. 2022. Successive extreme climatic events lead to immediate, large-scale, and diverse responses from fish in the Arctic. Global Change Biology doi: 10.1111/gcb.16153