Zooplankton link climate to capelin and polar cod in the Barents Sea

• Published in: Progress in oceanography 2024-08, Vol.226, p.103302, Article 103302
• Main Authors: Dalpadado, Padmini, Prokopchuk, Irina P., Bogstad, Bjarte, Skaret, Georg, Ingvaldsen, Randi B., Dolgov, Andrey V., Boyko, Anna S., Rey, Alina, Ono, Kotaro, Bagøien, Espen, Huse, Geir
• Format: Article
• Language: English
• Subjects: Amphipoda; Arctic; Arctic region; Barents Sea; biodiversity; biomass; Boreogadus saida; Calanus; climate; Climate impacts; diet; Euphausiacea; forage fish; Foraging ecology; Gadus morhua; Key drivers of zooplankton; lipids; Mallotus villosus; marine ecosystems; Metridia longa; net primary productivity; Norwegian Sea; oceanography; Pelagic fish; Predation pressure; species; summer; zooplankton
• ISSN: 0079-6611; 1873-4472
• DOI: 10.1016/j.pocean.2024.103302

•The Barents Sea is undergoing accelerated warming and sea ice loss.•Capelin and polar cod feed mainly on lipid rich sub-Arctic and Arctic zooplankton.•Atlantification alters prey composition towards more boreal species.•Significant negative relationship between capelin and mesozooplankton (1990–2022)•Predation and Atlantic water transport are key drivers of zooplankton biomass. Capelin (Mallotus villosus) and polar cod (Boreogadus saida) hold a fundamental position in the Barents Sea ecosystem as consumers of zooplankton while serving as forage fish for the commercial and ecological key species Atlantic cod (Gadus morhua). The ongoing warming and Atlantification of the Barents Sea, along with increasing net primary production, makes previously inaccessible northern areas available as feeding grounds for capelin. The opposite effect is anticipated for the ice-dependent polar cod. The transport of Atlantic water with boreal plankton from the Norwegian Sea is important for sustaining biodiversity and production in the Barents Sea. A decline of the medium-sized mesozooplankton biomass to a low level during 2016 to 2022 coincided with a strongly decreasing summer volume transport with the Atlantic Current. The low biomass of medium-sized zooplankton observed in later years raises concern about the feeding conditions now experienced by the higher trophic levels. Both capelin and polar cod feed predominantly on lipid rich sub-Arctic and Arctic zooplankton species. We found a significant inverse relationship between capelin and mesozooplankton biomass and a clear dietary shift from smaller to larger predator size. Smaller capelin (