Exploring planktonic foraminifera biogeography under changing climate conditions using a global ocean trait-based ecosystem model

Contributing to 23-56% of the modern total pelagic carbonate production, planktonic foraminifera are one of the main zooplankton calcifiers. Foraminifera are categorized into two groups; non-spinose and spinose. We developed ForamEcoGEnIE, the first global trait-based ecosystem model of planktonic foraminifera, to investigate the impact of climate change on non-spinose biogeography. The model accounts for the traits of calcification, size and feeding behaviour. We focus on the global warming under RCP6 and RCP8.5 scenarios. The model projects a global reduction in planktonic foraminifera biomass of 13.4% (RCP6) - 17.8% (RCP8.5) by 2100. For both RCP scenarios, biomass is projected to be increased in the subpolar North Atlantic and Southern Ocean, while low latitudes are facing the most significant biomass loss. By the end of the century, ForamEcoGEnIE predicts a local extinction of non-spinose species in the subtropic/tropic South Pacific and a huge decline (49.5- 70.9%) in the rest of the subtropics and tropics. The overall reduction of planktonic foraminifera stocks can potentially be associated with a major decrease in the ocean CaCO₃ production.