The response of marine algae to climate change

A new project at the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association dealing with the impact of climate change on marine phytoplankton will be funded by the European Research Council ERC with 1.4 million Euros. The project PhytoChange of Dr Bjoern Rost, who was among the 3% of successful applicants and succeeded against more than 9,000 competitors from all over Europe, will be funded by the EU for 5 years. The Independent Investigator Grant is designed to boost the careers of young excellent researchers wanting to build or strengthen their working group.

In the oceans's surface microalgae (phytoplankton) provide the nutritional basis for the marine food web. Using the sunlight as their source of energy for growth, they fix carbon dioxide (CO2) into organic compounds like sugars. By this process of photosynthesis phytoplankton binds large quantities of CO2, hereby strongly influencing the climate on our planet. Human-induced climate change causes large changes in marine ecosystems. The increase in atmospheric CO2 causes significantly higher aquatic CO2 concentrations and lowers pH values - the oceans get more acidic ('ocean acidification'). Rising temperatures affect surface ocean stratification, which in turn have an impact on the surface water light regime and nutrient input from deeper layers. The changes in these physico-chemical conditions affect the productivity and species composition of phytoplankton and thus the biogeochemical cycles coupled with the climate system. 'Predictions of how phytoplankton may respond to future changes at the cellular and ecosystem levels are a central task in climate research. We must go beyond the descriptive level and understand why photosynthesis, calcification, nitrogen fixation and other important cellular processes of marine algae are altered under the influence of climate change,' Rost explains the significance of his research project.

The new working group PhytoChange will examine the impact of environmental changes on selected phytoplankton groups, such as diatoms and coccolithophores. 'So far, experiments focussed predominantly on the impact of individual environmental factors and rarely on the combined effects,' says Rost. 'Therefore, we will analyse several influences simultaneously in our laboratory and field experiments. The methods we developed in the last few years will enable us not only to describe, but also to explain the species-specific responses to the altered environmental impacts.' The so-called Membrane-inlet Mass Spectrometry (MIMS) will play a central role in this context because it allows monitoring of gas exchange processes in real-time and examining several processes simultaneously. Working either with natural gases or with stable isotopes, many different processes can be studied in great detail. This allows, for instance, to determine how cells acquire inorganic carbon or to measure activities of key enzymes. The obtained data will further be exploited to develop and improve ecosystem and biogeochemical models as well as cell models. The working group PhytoChange cooperates with research institutes at the University of British Columbia (Canada), the University of Technology, Sydney (Australia), the Station Biologique de Roscoff (France), the Bar Ilan University (Israel), the University of Copenhagen (Denmark), and the University of Edinburgh (UK).