Theme 2
Project 3024

Double Trouble: Consequences of Ocean Acidification - Past, Present and Future - Consequences of Ocean Acidification for Phytoplankton production and losses
Project leader: Dr. C. P. D. Brussaard
Researcher(s): Dr. K. Crawfurd
Starting date:

The increase of pCO2 in the surface ocean profoundly affects the seawater carbonate system. However, very few processes other than calcification have been investigated so far despite the fact that pH and availability of CO2 are potentially important controls of, e.g. nutrient speciation or photosynthesis. We propose to study what the effects are of ocean acidification on marine phytoplankton, how are they modulated by other environmental stressors, and what are the consequences for marine ecosystems and ocean biogeochemical cycles. Phytoplankton forms the base of nearly all marine food chains. These photosynthetic microorganisms fix large amounts of CO2, account for almost half of the total primary production on Earth, and provide more than 99% of the organic matter used by marine food webs. Phytoplankton production sets upper limits to the overall activity of the pelagic food web and the biological pump. Major gaps in our understanding concern the synergistic effects from other stressors than increasing pCO2 and the ecological significance of the responses by the organisms. Therefore, this timely and comprehensive study will elucidate the effects of OA on phytoplankton physiology, health and cellular composition, as well as its sensitivity to sinking, grazing and virally induced cell lysis.