Reassessment of the global distribution and diversity of modern planktonic foraminifera from the FORCIS database

Abstract. Planktonic foraminifera (PF) shells are ubiquitous archives used as proxies in paleoceanography and play a crucial role in paleoclimate reconstructions. Species respond differently to abiotic and biotic factors and have shifted habitats with recent ocean warming. We re-evaluate the biogeographic limits of major PF species in the modern ocean, using the FORCIS data to extend the data coverage and explore potentially overlooked distributions of (small) species from the seminal works from the 1950s to the 1970s that were based on > 200 µm mesh-size plankton tows. We present a comprehensive update of their modern biogeography, vertical habitat distribution, and thermal tolerance using the FORCIS database, which includes all available water-column-sourced data from the last century. Our analysis confirms that the higher PF diversity is in the tropical and subtropical oceans. PF are observed in temperatures ranging from −2 to 31 °C, highlighting their remarkable thermal tolerance and/or adaptability to a wide range of temperatures. In addition, species that displayed a preferential habitat in lower latitudes in the 1950-to-1970 time interval (e.g. G. ruber) have been observed at higher latitudes over the last 50 years. Since the 1970s, medium-sized species have increased in abundance across all latitudes, from the tropical to polar oceans, a trend particularly evident in the extensive data from the eastern North Atlantic. The analysis of the FORCIS database updates the evolving biogeography of modern PF and advances our understanding of their ecology, providing revised benchmarks for paleoceanographic interpretations and the ecology of modern planktonic calcifiers.