Marine Biogeochemistry

Pelagic biogeochemical cycling: drivers and controls

Current Activities and Previous Work


The pelagic ocean, which encompasses the water column from the sea-surface to the ocean floor, hosts the largest ecosystem on Earth. The planktonic organisms inhabiting this ecosystem are responsible for about half of global primary production and form the base of the marine food web. They are the main drivers of elemental cycling, the exchange of climate relevant gases between ocean and atmosphere, including the sequestration of atmospheric CO2 in the deep ocean, and for the supply of organic matter to the sediments. Through these processes the pelagic ecosystem generates important feedbacks in the climate system. In turn, changes in environmental conditions due to global change will modulate pelagic ecosystems and biogeochemistry, with presently unknown consequences for marine ecosystem health, productivity and global climate.
Reliable prediction of future ocean and climate changes thus also requires a mechanistic understanding of biological responses to a rapidly changing marine environment. Due to the complexity and non-linear behaviour of marine ecosystems, unravelling those mechanisms is challenging.
Experimental perturbation studies that simulate effects of global change on key plankton species and communities provide crucial information on what to expect in the future. Accompanied by ocean observations and supported by advanced analytical instrumentation, those studies can provide information and data needed to refine our understanding and assessment of the societal impact of ocean change. A better process understanding is also essential for improving numerical models that can be used for prognostic scenario simulations into the future in order to inform society and policymakers.

Current activities and previous work


Head of the Research Unit Biological Oceanography:

Prof. Dr. Ulf Riebesell
GEOMAR | Helmholtz Centre for Ocean Research Kiel
West shore campus
Düsternbrooker Weg 20
D-24105 Kiel
Phone: +49 431 600-4444
Fax: +49 431 600-4446
e-mail: uriebesell(at)

Personal Assistant/Office Management of the Research Unit Biological Oceanography (RD2-BI):
Silvana Gagliardi
Phone: +49 431 600-4445
Fax: +49 431 600-4446
e-mail: sgagliardi(at)