Marine biodiversity trends

thalassionemaEmpirically, it has been shown that reductions in biodiversity can lead to reduced productivity and stability, which in turn impact critical ecosystem services. Despite this growing recognition, trends in marine biodiversity are poorly understood. Within the sMarD group we evaluate global trends in diversity of marine plankton and related changes in oceanic primary and secondary production. We aim to strengthen our understanding of global changes in the base of the marine food chain and their consequences for marine ecosystem functioning and services.

Synthesis Centre for Biodiversity Sciences (sDiv), German Centre for Integrative Biodiversity Research: workshop summary


Biodiversity Experimental Network (BEN)



There is growing evidence that human activities and climate change affect biodiversity. Many marine species have declined in abundance or are regionally extinct, but the consequences of biodiversity loss for functioning of marine ecosystems are still poorly understood. I am currently developing a Biodiversity Experimental Network that brings together researchers interested in climate change and marine biodiversity in order to run similar, simple-design experiments in sites located all over the world. The goal of this project is exploring alterations of plankton diversity in response to climate change and their consequences for functioning of marine ecosystems in two different dimensions: species-level and food-web level.

Stoichiometry & Biodiversity

OLYMPUS DIGITAL CAMERAStoichFun is a collaborative project on the stoichiometric constraints of biodiversity-functioning relationships. It merges the theory on ecological stoichiometry with the framework on biodiversity effects on ecosystem functioning to understand how resource use traits are stoichiometrically linked and how this transfers into primary and secondary production in terrestrial and aquatic ecosystems. In this framework I combine structural equation modelling and meta-analysis approaches to define general patterns of diversity-productivity relationships of producers and consumers.

Synthesis Centre for Biodiversity Sciences (sDiv), German Centre for Integrative Biodiversity Research: workshop summary

Global warming

OLYMPUS DIGITAL CAMERARising sea surface temperature has enormous consequences for marine ecosystems. Using mesocosms, I investigate how interactions in marine plankton communities change with global warming. Warming directly affects metabolic rates of marine organisms, but not in a balanced way. Heterotrophs are more sensitive to temperature change than autotrophs. Thus increasing grazing activity of zooplankton declines phytoplankton biomass in the ocean. On the other hand, rising sea surface temperature increases water column stratification reducing nutrient supply to the euphotic zone. This lack of nutrients in the upper part of the ocean limits phytoplankton growth with the consequences for the higher trophic levels. I am interested how interactions in pelagic communities will change with rising sea surface temperature and what consequences it will have for marine primary productivity in the future.

Projects: AQUASHIFT priority program of the German Research Fundation (DFG), MESOAQUA – a network of leading mesocosm facilities.

VIDEO Kiel MESOAQUA Experiment 2012

Ocean acidification

OLYMPUS DIGITAL CAMERACarbon dioxide released to the atmosphere dissolves into oceans and interacts with water to form carbonic acid. As anthropogenic CO2 emission increases, sea water becomes more acidic with dramatic consequences for calcifying organisms like corals or coccolithophorids. Most of the studies on the consequences of ocean acidification have focused on physiological response of calcifying organisms to decreasing pH. Calcifying microalgae like coccolithophorids response negatively to ocean acidification, but CO2 as a carbon source for autotrophs might increase productivity of other non-calcifying species. I am interested how ocean acidification affects phytoplankton community structure and competition between marine primary producers. In an experiment with the natural phytoplankton community from the North Atlantic, we could show that initial community structure has a stronger direct effect on phytoplankton biomass than increased CO2. This highlights the importance of species interactions for making predictions on marine phytoplankton dynamic with climate change.