Calcification response of planktic foraminifera to environmental change in the Western Mediterranean Sea during the industrial era

• Main Authors: Béjard, Thibauld M., Rigual-Hernández, Andrés S., Flores, José A., Tarruella, Javier P., Durrieu de Madron, Xavier, Cacho, Isabel, Haghipour, Neghar, Eglinton, Timothy, Sierro, Francisco J.
• Format: Report
• Language: English
• Published: Copernicus 2022
• Subjects: Planktic foraminifera; foraminifera calcification; biogeochemical cycles; Ocean Acidification; Mediterranean Sea; Ocean acidification
• Online Access: https://hdl.handle.net/20.500.11850/593078; https://doi.org/10.3929/ethz-b-000593078

The aim of this work is to investigate the variability of planktic foraminifera calcification in the northwestern Mediterranean Sea on seasonal, interannual and pre-industrial Holocene time scales. This study is based on data from a 12-year-long sediment trap record retrieved in the in the Gulf of Lions and seabed sediment samples from the Gulf of Lions and the promontory of Menorca. Three different planktic foraminifera species were selected based on their different ecology and abundance: Globigerina bulloides, Neogloboquadrina incompta, and Globorotalia truncatulinoides. A total of 273 samples were weighted in both sediment trap and seabed samples. As the traditionally used sieve fractions method is considered unreliable because of the effect of morphometric parameters on the foraminifera weight, we measured area and diameter to constrain the effect of these parameters. The results of our study show substantial different seasonal calcification patterns across species: G. bulloides showed a slight calcification increase during the high productivity period, while both N. incompta and G. truncatulinoides display a higher calcification during the low productivity period. The comparison of these patterns with environmental parameters revealed that Optimum Growth Conditions temperature and carbonate system parameters are the most likely to influence seasonal calcification in the Gulf of Lions. Interannual analysis suggest that both G. bulloides and N. incompta slightly reduced their calcification between 1994 and 2005, while G. truncatulinoides exhibited a constant and pronounced increase in its calcification that translated in an increase of 20 % of its shell weight for the 400–500 µm narrow size class. While our data suggest that carbonate system parameters are the most likely environmental parameter driving foraminifera calcification changes over the years. Finally, comparison between sediment trap data and seabed sediments allowed us to assess the changes of planktic foraminifera calcification during the late ...