Articles | Volume 13, issue 4
Biogeosciences, 13, 1037–1048, 2016

Special issue: Effects of rising CO2 on a Baltic Sea plankton...

Biogeosciences, 13, 1037–1048, 2016

Research article 23 Feb 2016

Research article | 23 Feb 2016

Negligible effects of ocean acidification on Eurytemora affinis (Copepoda) offspring production

Anna-Karin Almén1,2, Anu Vehmaa3, Andreas Brutemark2,3,a, Lennart Bach4, Silke Lischka4, Annegret Stuhr4, Sara Furuhagen5, Allanah Paul4, J. Rafael Bermúdez4,6, Ulf Riebesell4, and Jonna Engström-Öst1,2 Anna-Karin Almén et al.
  • 1Environmental and Marine Biology, Faculty of Science and Engineering, Åbo Akademi University, Artillerigatan 6, 20500 Åbo, Finland
  • 2Novia University of Applied Sciences Coastal Zone Research Team, Raseborgsvägen 9, 10600, Ekenäs Finland
  • 3Tvärminne Zoological Station, University of Helsinki, J.A. Palménin tie 260, 10900 Hanko, Finland
  • 4GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany
  • 5Department of Environmental Science and Analytical Chemistry, Stockholm University, Svante Arrhenius väg 8, 11418 Stockholm, Sweden
  • 6Facultad de Ingeniería Marítima, Ciencias Biológicas, Oceánicas y Recursos Naturales, Escuela Superior Politécnica del Litoral, ESPOL, Guayaquil, Ecuador
  • apresent address: Calluna AB, Torsgatan 30, 113 21 Stockholm, Sweden

Abstract. Ocean acidification is caused by increasing amounts of carbon dioxide dissolving in the oceans leading to lower seawater pH. We studied the effects of lowered pH on the calanoid copepod Eurytemora affinis during a mesocosm experiment conducted in a coastal area of the Baltic Sea. We measured copepod reproductive success as a function of pH, chlorophyll a concentration, diatom and dinoflagellate biomass, carbon to nitrogen (C : N) ratio of suspended particulate organic matter, as well as copepod fatty acid composition. The laboratory-based experiment was repeated four times during 4 consecutive weeks, with water and copepods sampled from pelagic mesocosms enriched with different CO2 concentrations. In addition, oxygen radical absorbance capacity (ORAC) of animals from the mesocosms was measured weekly to test whether the copepod's defence against oxidative stress was affected by pH. We found no effect of pH on offspring production. Phytoplankton biomass, as indicated by chlorophyll a concentration and dinoflagellate biomass, had a positive effect. The concentration of polyunsaturated fatty acids in the females was reflected in the eggs and had a positive effect on offspring production, whereas monounsaturated fatty acids of the females were reflected in their eggs but had no significant effect. ORAC was not affected by pH. From these experiments we conclude that E. affinis seems robust against direct exposure to ocean acidification on a physiological level, for the variables covered in the study. E. affinis may not have faced acute pH stress in the treatments as the species naturally face large pH fluctuations.

Short summary
We studied the effects of ocean acidification (OA) on the aquatic crustacean Eurytemora affinis and measured offspring production in relation to pH, chlorophyll, algae, fatty acids, and oxidative stress. No effects on offspring production or pH effects via food were found. E. affinis seems robust against OA on a physiological level and did probably not face acute pH stress in the treatments, as the species naturally face large pH fluctuations.
Final-revised paper