Hiding in the shadows: effects of environmental stressors on male calanoid copepods - An insider's view

Polar ecosystems are particularly vulnerable to effects caused by environmental stressors of anthropogenic origin, such as ocean acidification (OA) and ocean warming (OW), both of which are disproportionally affecting the Arctic region. Calanoid copepods of the genus Calanus are key species in the arctic food web and constitute up to 90% of the zooplankton biomass in arctic shelf regions. To date, research on the effects of OA on arctic calanoid copepods has focussed on female and early life stages. Male calanoid copepods and their response to environmental stressors, however, are largely understudied. This is likely because they are short lived and occur only fleetingly in the middle of the polar night as opposed to the females, which are much longer lived and survive through the return of the sun into spring and summer. Interestingly, male copepods may be uniquely vulnerable to ocean acidification: while females and young stages have proven to be relatively robust to ocean acidification, exposing male copepods to conditions similar to ocean acidification caused significant reductions in survival of young in a calanoid copepod species. The lack of knowledge of how global environmental change drivers affect males during winter is therefore an important knowledge gap to fill for understanding Calanus population dynamics in future oceans. This project aims at shedding light in the physiological responses of male copepods when presented with levels of environmental stressors (such as OA and OW) at levels projected for the near future in the arctic region. Kongsfjorden has been chosen as the location for this study, given it represents one of the best studied arctic fjord systems and is a reference site for marine science and monitoring. In addition, the Kongsfjorden fauna is unique in diversity and abundance, and is considered as an early indicator for changes associated with global change related stressors, such as OA or OW.