Fate of the key Arctic copepod Calanus glacialis in a changing environment 

Janne Søreide1, Daniela Freese2, Lauris Boissonnot3, Maja K Hatlebakk1, Malin Daase4, Martin Graeve5 and Barbara Niehoff6, (1)The University Centre in Svalbard, Arctic Biology, Longyearbyen, Norway, (2)Alfred Wegener Institute, Bremerhaven, Germany, (3)Alfred Wegener Institute / University Centre in Svalbard, Chemical Ecology / Arctic Biology, Bremerhaven / Longyearbyen, Germany, (4)UiT The Arctic University of Norway, Department of Arctic and Marine Biology, Tromsø, Norway, (5)Alfred Wegener Institute, Chemical Ecology, Bremerhaven, Germany, (6)Alfred Wegener Institute, Polar Biology, Bremerhaven, Germany
Abstract:
High latitude marine ecosystems experience strong seasonality in incoming light and thus primary production and food availability. Herbivorous calanoid copepods of the genus Calanus may comprise up to 90% of the mesozooplankton biomass in Arctic seas. They are able to build up large lipid deposits during the short, but productive summer and to survive food shortage in winter by entering a dormant state, referred to as diapause. The ongoing reduction in sea ice thickness and extent will significantly change the underwater light climate and thus the timing, quantity and quality of the primary producers in the Arctic with possible consequences for the grazers. Up to date we have very limited knowledge on the overwintering ecology and physiology of Calanus spp., and their ability to respond to external cues like light and food while in diapause. In the research project “Climate effects on planktonic food quality and trophic transfer in Arctic marginal ice zones (CLEOPATRA II)” we combined extensive field and experimental work to investigate the winter ecology and physiology of Calanus glacialis, endemic to the Arctic. This relatively large and lipid-rich copepod prefer seasonal ice covered shelf seas and thus have evolved somewhat different physiological adaptation and behavior than its sibling species in the deeper oceanic realms, C. finmarchicus in the North Atlantic and C. hyperboreus in the Arctic Ocean. Key project results will be presented which all add up to the conclusion that the oldest overwintering stages of C. glacialis do not enter a true diapause in winter, and thus this species is able to respond to rapid changes in its surrounding physical and biological environment.