Ocean acidification (OA), i.e. the uptake of man-made CO2 and the subsequent decline in seawater pH, and ocean warming have the potential to severely affect the performance of marine organisms, their trophic interactions and, finally, whole ecosystems. In Arctic waters, the calanoid copepod species Calanus finmarchicus, C. glacialis and C. hyperboreus are key components of the lipid-based food web, linking primary production and higher trophic levels. Within the framework of the research project BIOACID (Biological Impacts of Ocean Acidification), this study aims to provide a comprehensive overview on the sensitivity of the three Calanus species to ocean acidification and ocean warming. In controlled laboratory CO2 incubation experiments, direct physiological and ecological effects of elevated pCO2 were investigated in both active and diapausing Calanus life stages, and synergistic effects of pCO2 and temperature were studied. In addition, indirect effects of OA via altered food regimes were tackled in an ecosystem-scale experiment within the framework of the SOPRAN (Surface Ocean Processes in the Anthropocene) mesocosm study in 2011.
Late copepodites and adult females of C. finmarchicus, C. glacialis and C. hyperboreus have been proven to be rather robust to elevated seawater pCO2 in terms of direct effects. In active life stages, metabolic rates and thus the energetic demand were unaffected by CO2 concentrations of up to 3000 μatm (pH 7.2), which is well beyond the levels projected to occur in surface waters during the next three centuries. Accordingly, food uptake and body mass were not altered, suggesting that also the available energy for processes such as reproduction and growth will not directly be affected by OA in future decades. (…)
Hildebrandt N., 2014. The response of three dominant Arctic copepod species to elevated CO2 concentrations and water temperatures. PhD thesis, University of Bremen, 189 pp. Thesis.
