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Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 14, 2245-2266, 2017
https://doi.org/10.5194/bg-14-2245-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
04 May 2017
Low planktic foraminiferal diversity and abundance observed in a spring 2013 west–east Mediterranean Sea plankton tow transect
Miguel Mallo1, Patrizia Ziveri1,2, P. Graham Mortyn1,3, Ralf Schiebel4, and Michael Grelaud1 1Institute of Environmental Science and Technology (ICTA), Autonomous University of Barcelona (UAB), Bellaterra 08193, Spain
2Catalan Institution for Research and Advanced Studies (ICREA), Pg. Lluís Companys 23, Barcelona 08010, Spain
3Geography Department, UAB, Bellaterra 08193, Spain
4Climate Geochemistry, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz, Germany
Abstract. Planktic foraminifera were collected with 150 µm BONGO nets from the upper 200 m water depth at 20 stations across the Mediterranean Sea between 2 May and 2 June 2013. The main aim is to characterize the species distribution and test the covariance between foraminiferal area density (ρA) and seawater carbonate chemistry in a biogeochemical gradient including ultraoligotrophic conditions. Average foraminifera abundances are 1.42 ± 1.43 ind. 10 m−3 (ranging from 0.11 to 5.20 ind. 10 m−3), including 12 morphospecies. Large differences in species assemblages and total abundances are observed between the different Mediterranean sub-basins, with an overall dominance of spinose, symbiont-bearing species indicating oligotrophic conditions. The highest values in absolute abundance are found in the Strait of Gibraltar and the Alboran Sea. The western basin is dominated by Globorotalia inflata and Globigerina bulloides at slightly lower standing stocks than in the eastern basin. In contrast, the planktic foraminiferal assemblage in the warmer, saltier, and more nutrient-limited eastern basin is dominated by Globigerinoides ruber (white). These new results, when combined with previous findings, suggest that temperature-induced surface water stratification and food availability are the main factors controlling foraminiferal distribution. In the oligotrophic and highly alkaline and supersaturated with respect to calcite and aragonite Mediterranean surface water, standing stocks and ρA of G. ruber (white) and G. bulloides are affected by both food availability and seawater carbonate chemistry. Rapid warming increased surface ocean stratification impacting food availability and changes in trophic conditions could be the causes of reduced foraminiferal abundance, diversity, and species-specific changes in planktic foraminiferal calcification.

Citation: Mallo, M., Ziveri, P., Mortyn, P. G., Schiebel, R., and Grelaud, M.: Low planktic foraminiferal diversity and abundance observed in a spring 2013 west–east Mediterranean Sea plankton tow transect, Biogeosciences, 14, 2245-2266, https://doi.org/10.5194/bg-14-2245-2017, 2017.
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Single-celled living calcareous planktic foraminifera data across the Mediterranean Sea suggest that stratification of the surface water column, food availability, temperature, and seawater carbonate chemistry are the main factors controlling their distribution and mass. Increasing temperature, salinity, surface ocean stratification, and trophic conditions could be the causes of reduced abundance, diversity and species-specific changes in calcification in planktic foraminifera.
Single-celled living calcareous planktic foraminifera data across the Mediterranean Sea suggest...
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