Scientific Projects & Research

BIOACID III – Biological Impacts of Ocean Acidification

Project Description

The ongoing acidification of the world‘s oceans is constantly changing seawater chemistry. This in Earth’s history comparably rapid process poses a risk for marine ecosystems and the global climate. Impacts on biological and biogeochemical cycles threaten the functioning of marine assemblages. The reduced capacity of the oceans for the uptake of anthropogenic CO2 has the potential to cause negative climate feedbacks as for example a higher accumulation of  CO2 in the atmosphere. Contrary to this development, our understanding of the consequences of ocean acidification remains at a comparably poor level. A high number of studies on single species offer valuable insights into the potential impacts. However, the net effect remains often unknown as real ecosystems are a complex network with many interacting factors.

The central aspect of the third phase of the BIOACID project is the comparison and the synthesis of available data in order to gain new scientific insights into the influence of ocean acidification on elemental cycles and potential feedbacks on the climate system. The results will be used for ecosystem modelling and by this help to make better predictions for the future of marine ecosystems.The importance of good models becomes apparent under consideration of the economical and societal importance of the oceans. An increase of atmospheric CO2 concentrations poses a major threat for human society, which will increase inevitably in the near future.


  • Carbon turnover related to organic substrate quality and functioning of microbial communities

This project aims for a better understanding of the influence of elevated CO2 concentrations on microbial communities and the production and consumption of dissolved organic matter (DOM) in different marine ecosystems. Two high resolution data sets including detailed information on microbial community and DOM composition were obtained from extended acidification experiments in BIOACID phase II. The central aspect of BIOACID phase III will be the synthesis of these data in order to obtain new insights on the impact of ocean acidification on the global carbon cycle and potential feedbacks for the climate.

  • Quantifying the relative importance of direct and indirect effects of increasing CO2 and temperature on the functioning of benthic and pelagic primary producers – an across season and system comparison using structural equation modelling (SEM)

Aim of the second sub-project is the identification and quantification of direct and indirect effects of elevated CO2 concentrations as single driver or in combination with elevated temperatures. Indirect effects are potentially a result of modified interactions between different species and between different trophic levels in marine ecosystems. In a comprehensive approach we investigate the influence of elevated CO2 and temperature on marine primary production in soil associated (benthic) and open ocean (planctonic) communities. Further, we test whether these effects show seasonal variablility and how they differ between top-down or bottom-up controlled systems.

Project Management

GEOMAR | Helmholtz-Centre for Ocean Research Kiel


Project Leader:
Prof. Dr. Ulf Riebesell, GEOMAR, Kiel (chair)
Prof. Dr. Thorsten Dittmar, ICBM-MPI Brückengruppe für Marine Geochemie, Universität Oldenburg

Project Partners (ICBM):

Marine GeochemieDr. Thorsten Dittmar
PlanktologieProf. Hellmut Hillebrand


  • Christian-Albrechts-Universität zu Kiel
  • GEOMAR | Helmholtz Centre for Ocean Research Kiel
  • Helmholtz Centre for Materials and Coastal Research, Geesthacht
  • Kiel Institute for the World Economy
  • Leibniz-Institute for Freshwater Ecology and Inland Fisheries, Berlin
  • Leibniz-Institute for Baltic Sea Research Warnemünde
  • University of Bremen
  • University of Rostock


2 Years (2015 - 2017)

Financial Support

German Federal Ministry of Education and Research (BMBF)


(Changed: 19 Jan 2024)  | 
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