Predicting DMS(P) production in a high carbon dioxide world:Does algal carbon-utilization provide an answer?

• Main Authors: Bach, Mareike, Stefels, Jacqueline, van Leeuwe, Maria, Elzenga, Theo
• Format: Conference Object
• Language: English
• Published: 2019
• Subjects: Antarctic; Southern Ocean; Antarctic Peninsula; Antarc*; Ocean acidification; Sea ice
• Online Access: https://hdl.handle.net/11370/9ae46770-732b-49ee-b12b-15d3e9c2f35c; https://research.rug.nl/en/publications/9ae46770-732b-49ee-b12b-15d3e9c2f35c; https://pure.rug.nl/ws/files/956851879/abstracts2019-1.pdf; https://www.gher.uliege.be/cms/c_7459213/en/gher-colloquium-2019-program

Climate change is considered a global threat to humankind in our current understanding. A region showing some of the largest measurable changes in surface-ocean temperature is the West Antarctic Peninsula (WAP). Increasing winter temperature of about 6 °C since 1951 has led to a 41 % decrease in mean sea ice cover over the past 50 years. The increasing levels of CO2 result in a lower oceanic pH. It is uncertain how the ecosystem, especially the productive phytoplankton community of the Southern Ocean, will react to these major factors: sea ice retreat and ocean acidification. Here I will present an outline of the experiments that are planned to investigate how the rising levels of CO2 and the retreat of sea ice will impact the phytoplankton communities in the Southern Ocean. Especially, the physiological mechanisms underlying the sulfur and the carbon cycle will be studied in detail. The focus will be on the production of the algal metabolite DMSP (dimethylsulfoniopropionate) and its potential coupling to algal carbon uptake mechanisms and subsequently the production of the climate active gas DMS (dimethylsulfide). The study involves both controlled laboratory studies and field experiments at the WAP considering environmental factors as temperature, salinity, pH and light. DMSP-production will be tracked using stable isotope addition experiments and analyzed by Protontransfer-reaction mass spectrometry (PTR-MS) combined with Cavity Ring down spectroscopy to measure isotope ratios of total particulate organic carbon (POC). The carbon uptake mechanism will be studied using an isotopic disequilibrium technique. We hypothesize that the mechanisms that regulate DMSP production are related to the carbon-uptake mechanism of the algae involved. We hope to get an insight into how the algal sulfur and carbon cycles are linked and how CO2 and DMS concentrations will develop in the ocean and ultimately in the atmosphere under changing climate conditions.