1. Objectives

The overall objective of PEACE is to assess the role of pelagic calcification and export of CaCO₃ production in climate regulation. Specific objectives are:

1) to study of the net ecosystem dynamics during coccolithophorid blooms,
2) to unravel the link between the microbial community, grazing, TEP dynamics, carbon export and DMS cycling during coccolithophorid blooms,
3) to assess the effects of ocean acidification on coccolithophorid metabolism and TEP production, and
4) to model coccolithophorid dynamics and their impact on ocean dissolved inorganic carbon (DIC) chemistry.

These objectives fully comply with the priority themes within the research areas "Climate" and "Atmosphere" defined in the first call for proposals launched by the Belgian Federal Public Planning Service Science Policy in the framework of the research programme "Science for a Sustainable Development (SSD)". Among them, it calls for the study of the role of the oceans and marginal zones in the carbon cycle on one hand and for the forecasting of trends on the other hand.

2. Methodology and approaches

The aims of the present project will be achieved using a transdisciplinary approach that combines process-oriented field investigations with laboratory experiments and modelling tools.

Field investigations, supported by remote sensing data, will be conducted in the Northern Gulf of Biscay (one of the main coastal European marine areas) where frequent and recurrent coccolithophorid blooms are observed. The Belgian biogeochemistry community has investigated this region since the late 1980s within the framework of the PPS Science Policy "Global Change" programme to study the "Production, transport and fate of organic matter and associated elements in the marine systems" and of the EU MAST programme to study the exchange processes at the ocean margins (OMEX I and II projects). The SPSD-II funded CCCC project also focused on the same region to evaluate the role of oceanic production and dissolution of calcium carbonate in climate change. Therefore, long-term series of physical, biological and chemical parameters exist for model validation. A suit of basic parameters will be measured in the water column (temperature, salinity, pH, total alkalinity, dissolved organic and inorganic carbon, dissolved oxygen, nutrients). To decipher the impact of coccolithophores on climate relevant processes, we will determine key parameters of calcification and associated processes such as algal characterisation and bacterial community structure, rate of organic and inorganic carbon production, degradation and export, and air-sea exchange of CO₂ and DMS. In addition, we will assess the role of TEP in CO₂ sequestration during coccolithophorid blooms. In situ surveys will be supported by laboratory experiments (both batch and continuous cultures) in order to further investigate specific coupling. This will allow a comprehensive parameterisation of the climate oriented 1D mechanistic biogeochemical model of coccolithophorid blooms. Ultimate upgrade from a mechanistic model to a predictive model will require laboratory experiments where predicted increase of temperature and oceanic acidification are simulated.

Finally, synthesis on the acquired data and future projections in relation to increasing pCO₂ and ocean acidification will be achieved through the application of a 1D biogeochemical model. The model will explicitly describe the DIC chemistry and the coccolithophorid dynamics (calcification, export of organic carbon and CaCO₃). It will be specifically tuned with the newly and previously acquired field and laboratory data (e.g. mesocosm experiments) and will be coupled with a hydrodynamic model of the region.

3. Strategic importance and link to international programmes

In order to provide an accurate prediction of ocean organic and inorganic carbon storage, it is essential to understand the physical, chemical and biological controls on present and future marine ecosystem and ocean carbon dynamics including biogeochemical responses to and feedbacks on climate change. One of the rising and alarming issues concerns the ocean acidification due to increasing atmospheric CO₂ concentration and its impacts. The important role of calcification in the global carbon cycle has been increasingly recognised. A better understanding of the effects of changing pH and carbon system parameters on marine biogeochemical cycles and organisms is urgently needed to allow the evaluation of different scenarios of CO₂ increase and mitigation strategies. Redressing this situation should be a high priority within research agendas, especially in the context of the preparation of the next Intergovernmental Panel on Climate Change (IPCC) assessment report (2007) and to contribute to the scientific basis of the drafting of the second Kyoto Protocol (2012). As pointed out in a document prepared by a group of global change scientists on ocean acidification (The Royal Society of London, 2005), this issue also needs to be kept under review by international scientific bodies such as the Intergovernmental Oceanographic Commission (IOC), the Scientific Committee on Oceanic Research (SCOR) and the International Geosphere Biosphere Programme (IGBP).

The present research will contribute to the core projects of the IGBP: Analysis, Integration and Modelling of the Earth System (AIMES), Global Ocean Ecosystem Dynamics (GLOBEC), Integrated Marine Biogeochemistry and Ecosystem Research (IMBER), Land-Ocean Interactions in the Coastal Zone (LOICZ) and Surface Ocean-Lower Atmosphere Study (SOLAS).

4. Complementarity with other previous and current research projects

The PEACE project can be considered as the continuation of the SPSD-II CCCC project, although with new partners. It will benefit from the existing databases established in the area since the late 1980s within the framework of the PPS "Global Change" and SPSD-II "Climate" programmes, and the EU OMEX I and II projects. PEACE will, in addition, profit from existing databases established during two mesocosm experiments carried out in the framework of the Pelagic Ecosystem CO₂ Enrichment Study (PEECE) in which AWI, ULg and ULB were involved. It also contributes to the goals of the on-going FP6 EU Integrated Project CARBOOCEAN (of which ULB and ULg are PIs), aiming at an improved quantification of the marine sources and sinks for CO₂ on a time scale of -200 years to +200 from now with special focus on the Atlantic Ocean. It falls furthermore in the scopes of the SOLAS.be PPS Science Policy cluster (of which ULB and ULg are PIs).