In the Arctic marine ecosystem, Calanus hyperboreus and C. glacialis are keys species. Copepods account for more than 80% of zooplankton biomass and are a primary lipid-rich food source for fish such as polar cod and Atlantic cod. During the short growing season, they accumulate the energy in the form of lipid for surviving the long, dark, and food-poor winter and for early reproduction in the winter-spring. Millions of Arctic copepods start to overwinter in late summer/early autumn at depths varying between 300 – 1500 m below the sea surface. Numerically, it is one of the largest animal migrations on earth. Overwintering of Arctic copepods has been known to affect the regional climate and carbon sequestrations in the ocean.
Arctic regions experience the fastest changes from climate change, a crucial question is how environmental stressors such as ocean warming and acidification may act in concert to affect the overwintering of these key Arctic copepods. Furthermore, extreme warming periods such as the marine heatwaves (MHWs) have caused dramatic changes in marine ecosystems worldwide. The frequency, magnitude and severity of marine heatwaves are predicted to increase rapidly in the Arctic regions, particularly in late summer and autumn, but we do not know how MHWs may affect the Arctic species. Another question is how ocean acidification may modulate the marine heatwave effect.
In this Young Research Talent (YRT) project, we will investigate the impacts of marine heatwaves and ocean acidification on the overwintering of these key Arctic copepod species. Furthermore, this YRT project will pave the way for the scientific community to explore multiple-stressor effects on overwintering thousands of high-latitude species from protozoans to reptiles that go into the diapause during the winter.
Capacity to survive the long, dark, cold and unproductive winter is critical for most Arctic species. Many Arctic ectotherms have therefore evolved special adaptations to severe winter conditions by investment in large storage deposits combined with lowering metabolism to a minimum in winter. However, we do not know how multiple stressors may affect overwintering Arctic species. This is a critical period and failure in surviving winter will have ecological consequences for the entire ecosystem. This pump priming project aims to fill this huge knowledge gap by empirically investigating the highly complex interaction of dominant stressors such as marine heatwaves and ocean acidification to cause direct, delayed, and/or transgenerational effects in key Arctic copepods before, during and after the overwintering period. We will empirically conduct unique, months-long, multiple-season experiments testing for the single and combined effects of marine heatwaves and ocean acidification on Arctic copepods in an ecologically relevant context of overwintering. As marine heatwaves occur randomly in space and time, which do not provide a clear signal to drive directional selection for adaptation, we will test whether and to which extent transgenerational acclimation (environmental conditions experienced by parents alter the offspring performance) may interact with developmental acclimation (physiological adjustments) in shaping their vulnerability to these stressors. This project will pave the way for the scientific community to explore multiple-stressor effects on overwintering thousands of high-latitude species from protozoans to reptiles that go into the diapause during the winter. Project outputs are also highly relevant for Target 14.a: Increase scientific knowledge, research and technology for ocean health, UN Sustainable Development Goal 14 - Life below water and is timely for the UN Decade of Ocean Science for Sustainable Development (2021-2030).