ADAPTation von COCCOlithophoriden-Gemeinschaften auf Umweltveränderungen im Südozean (ADAPT-COCCO)

The marine communities of the Southern Ocean are extremely vulnerable to anthropogenic environmental change. Warming and acidification of surface waters are already impacting the plankton communities that form the basis of Southern Ocean marine food webs. The productivity of the plankton also influences the ability of the Southern Ocean to absorb carbon dioxide from the atmosphere. With regions of the Southern Ocean set to experience some of the highest rates of ocean acidification over the coming century, it is imperative to design evidence-based strategies for this marine environment of global importance. Single-celled coccolithophore algae are the dominant group of calcifying phytoplankton in the Southern Ocean. As marine calcifyers they will be impacted by reduced surface ocean carbonate ion concentrations as a result of ocean acidification. Although satellite estimations suggest that calcification rates have recently decreased in broad areas of the Southern Ocean, there is still controversy about whether ocean acidification will promote or reduce coccolithophore calcification rates in the future. This project will address this scientific question focusing on different late Quaternary time slices and by using scanning electron microscopy (for coccolithophore assemblages), an automated system of coccolith recognition -SYRACO- (for coccolith mass estimates) and organic geochemistry (for [CO₂(aq)] estimates). The findings from this proposal will help to test the limits of [CO₃^2-] and temperature controls on coccolithophore occurrences and will provide a key baseline dataset for monitoring 21st Century changes in Southern Ocean phytoplankton communities.