Size normalizing planktonic Foraminifera abundance in the water column

• Published in: Limnology and Oceanography: Methods
• Main Authors: Chaabane, Sonia, de Garidel‐thoron, Thibault, Giraud, Xavier, Meilland, Julie, Brummer, Geert‐jan, Jonkers, Lukas, Mortyn, P. Graham, Greco, Mattia, Casajus, Nicolas, Kucera, Michal, Sulpis, Olivier, Kuroyanagi, Azumi, Howa, Hélène, Beaugrand, Gregory, Schiebel, Ralf
• Other Authors: Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Fondation pour la recherche sur la Biodiversité (FRB), Center for Marine Environmental Sciences Bremen (MARUM), Universität Bremen, Universitat Autònoma de Barcelona = Autonomous University of Barcelona = Universidad Autónoma de Barcelona (UAB), Institute of Marine Sciences / Institut de Ciències del Mar Barcelona (ICM), Consejo Superior de Investigaciones Cientificas España = Spanish National Research Council Spain (CSIC), Tohoku University Sendai, Université d'Angers (UA), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Nord ), Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: [PHYS]Physics [physics]; Planktonic foraminifera
• Online Access: https://hal.science/hal-04700539; https://doi.org/10.1002/lom3.10637

International audience Abstract Planktonic Foraminifera have been collected from the water column with different plankton sampling devices equipped with nets of various mesh sizes, which impedes direct comparison of observed quantifications. Here, we use data on the community size structure of planktonic Foraminifera to assess the impact of mesh size on the measured abundance (ind m −3 ) of planktonic Foraminifera. We use data from the FORCIS database (Chaabane et al., 2023, Scientific Data 10: 354) on the global ocean at different sampling depths over the past century. We find a global cumulative increase in abundance with size, which is best described using a Michaelis–Menten function. This function yields multiplication factors by which one size fraction can be normalized to any other size fraction equal to or larger than 100 μm. The resulting size normalization model is calibrated over a range of different depth intervals, and validated with an independent dataset from various depth ranges. The comparison to Berger's (1969, Deep. Res. Oceanogr. Abstr. 16: 1–24) equivalent catch approach shows a significant increase in the predictive skill of the model. The new size normalization scheme enables comparison of Foraminifera abundance data sampled with plankton nets of different mesh sizes, such as compiled in the FORCIS database. The correction methodology may be effectively employed for various other plankton groups such as diatoms and dinoflagellates.