Unravelling the fate of coccolithophores (marine microplankton) during times of rapid environmental change

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The global climate system has many interacting components and is inherently complex. One of the most challenging tasks in understanding current global change is the untangling and quantification of the involved components and processes. While several processes have been successfully modeled by treating the Earth mainly as a physical or chemical system, the quantitative characterization of global change in the biosphere, for example in the marine ecosystem, is lagging far behind. However, any assessment of future climate change requires knowledge of the full range of natural variability. Therefore, the proposed research project is designed towards gaining a fundamental understanding of how environmental change affects the marine ecosystem, especially coccolithophores, a major group of single celled marine phytoplankton. Coccolithophores are of particular interest because they play an important part in the marine carbon cycle both as primary producers and calcite producers that affect the CO2 levels of the ocean. They are estimated to contribute 46% of the particulate organic carbon fixation in the ocean, and about 50% of the deep sea carbonate production. However, little is currently known on how rapid climate variability affects the production, diversity and evolution of coccolithophores. Thus, the proposed research project aims to determine how coccolithophores are affected by rapid environmental changes such as anthropogenic pollution during the last 200 years (e.g. increasing CO2 levels), the El Niño Southern Oscillation (ENSO) and Monsoons from key localities that sensitively record these rapid climate changes (e.g., the Gulf of California, the Cariaco Basin, and the Arabian Sea). In particular, the response of coccolithophores flux, assemblage composition and morphological variations of key species such as Emiliania huxleyi, Gephyrocapsa oceanica and Florisphaera profunda to environmental change will be analysed using sediment trap and plankton samples. The obtained data will be subsequently used to reconstruct as well as examine the impact of climate changes during the Holocene on coccolithophores from annually laminated sediments accumulated at the key localities. The application of recently developed techniques and proxies most suitable for ultra high resolution analysis of laminated sediments guarantees high quality data; the knowledge obtained in this way will be essential in assessing the impact of future global change on the marine ecosystem.