Assessing the response of planktonic foraminifera biodiversity to multiple climatic stressors (FORCIS database)

Abstract:

Ocean acidification (OA) represents a major threat to marine calcifying organisms, notably in planktonic foraminifera. Yet, historical changes in diversity and distributions of these species have not been globally assessed, and studies are focused on regional to basin-wide studies. Here, we present the first analyses of the FORCIS (Foraminifera Response to Climatic Stress) project, which aims to gather foraminiferal species diversity and distribution from the global ocean from 1910 to today. To date, assembled faunal datasets from plankton nets (~7000 samples) combined with Continuous Plankton Recorder (~160000 samples) and sediment trap (~7000 samples) datasets give synoptic views of historical changes in planktonic foraminifera, at different resolutions (spatial, vertical, and seasonal).

Our first analyses show that the planktonic foraminifera standing stocks span a very large range of magnitudes, typically from 1 specimen to 10x specimens/m³ up to thousands of individuals per cubic meter. The standing stock presents a positive correlation with the species richness. The latitudinal diversity gradient shows the same trends as the surface sediment ForCenS dataset with higher abundances are encountered in the mid-latitudes. In the FORCIS database plankton net subset, we detect a slight poleward increase of foraminifera abundance during the last 30 years, in agreement with observations from North Atlantic CPR time-series. The relative impacts of the abiotic parameters on foraminifera biodiversity and abundance over the last decades are being assessed, taking into account known heterogeneities in the sampling methods (mesh size, seasonal, horizontal and vertical resolution). We plan to use this database to constrain ecophysiological and population models in this group that will ultimately be used to better understand the impacts of past and ongoing OA on foraminifera.