Planktonic foraminifera are one of the primary calcifiers in the modern ocean, contributing 23%–56% of total global pelagic carbonate production. However, a mechanistic understanding of how physiology and environmental conditions control their abundance and distribution is lacking, hindering the projection of the impact of future climate change. This understanding is important, not only for ecosystem dynamics, but also for marine carbon cycling because of foraminifera's key role in carbonate production. Here we present and apply a global trait-based ecosystem model of non-spinose planktonic foraminifera (‘ForamEcoGEnIE’) to assess their ecology and global distribution under future climate change. ForamEcoGEnIE considers the traits of calcium carbonate production, shell size, and foraging. It captures the main characteristic of biogeographical patterns of non-spinose species – with maximum biomass concentrations found in mid- to high-latitude waters and upwelling areas. The model also reproduces the magnitude of global carbonate production relatively well, although the foraminifera standing stock is systematically overestimated. In response to future scenarios of rising atmospheric CO2 (RCP6 and RCP8.5), on a regional scale, the modelled foraminifera biomass and export flux increases in the subpolar regions of the North Atlantic and the Southern Ocean while it decreases everywhere else. In the absence of adaptation, the biomass decline in the low-latitude South Pacific suggests extirpation. The model projects a global average loss in non-spinose foraminifera biomass between 8% (RCP6) and 11% (RCP8.5) by 2050 and between 14% and 18% by 2100 as a response to ocean warming and associated changes in primary production and ecological dynamics. Global calcium carbonate flux associated with non-spinose foraminifera declines by 13%–18% by 2100. That decline can slow down the ocean carbonate pump and create short-term positive feedback on rising atmospheric pCO2.
Bibliographical noteFunding Information:
This work was supported by the European Research Council ‘PALEOGENiE’ project (ERC‐2013‐CoG617313), by National Science Foundation (OCE‐1851866) to MG, by NERC grant number NE/N011708/1 to FMM and NE/P019439/1 to DNS, as well as a Wolfson Merit Award to DNS. A.R. recognizes support from the Heising Simons Foundation. We would like to thank Kirsty Edgar for sharing the data analysis for the Figure 1a . We also thank the Editor and the two anonymous reviewers for their thoughtful and constructive feedback which improved an earlier version of the manuscript and the supporting information.
© 2021 The Authors. Global Change Biology published by John Wiley & Sons Ltd.
- calcium carbonate export
- plankton ecology
- planktonic foraminifera
- trait-based model