GC10-Pliocene-45, updated on 15 Jul 2022
The warm Pliocene: Bridging the geological data and modelling communities
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Role of the closure of the Central American Seaway in gigantism of planktic foraminifers

Chloe Todd1,2, Ruby Barrett1, Heather Birch1, Daniel Hill3, Jamie Wilson1, Marci Robinson4, and Daniela Schmidt1
Chloe Todd et al.
  • 1University of Bristol, School of Earth Sciences, Bristol, UK
  • 2University of Southampton, Ocean and Earth Science, Southampton, UK (C.L.C.Todd@soton.ac.uk)
  • 3University of Leeds, School of Earth and Environment, Leeds, UK
  • 4Florence Bascom Geoscience Center, U.S. Geological Survey, Reston, VA, USA

Size is fundamentally important in individual planktic foraminifers as it determines the number of offspring and hence reproductive success. Over evolutionary timescales, individuals tend to increase in size, altering the average size of assemblages; in the last million years, individuals were larger than at any other time in the geological record. This pattern is specifically driven by size increases in tropical and subtropical taxa in the Plio-Pleistocene. Here we use a taxon-free approach to assess what facilitated this novelty and to quantify the response of planktic foraminifers to both long and short time-scale environmental changes. We focus on the Pliocene, a time interval characterized by the closure of the Central American Seaway (CAS) and the short glaciation at marine isotope stage (MIS) M2. We measured size in foraminiferal assemblages using automated microscopy across 24 globally distributed PRISM locations, from subpolar to tropical environments. The 95th percentile was calculated on the maximum diameter measurements of 1.28 million specimens. Although there is a slight decrease in the average size of the assemblage in the high latitudes from the Early to Late Pliocene, with minimal changes in the tropics, results indicate little to no effect on foraminiferal size across MIS M2. The results show an unexpected stability and resilience against the reorganization of the tropical oceans associated with the closure of the CAS.

How to cite: Todd, C., Barrett, R., Birch, H., Hill, D., Wilson, J., Robinson, M., and Schmidt, D.: Role of the closure of the Central American Seaway in gigantism of planktic foraminifers, The warm Pliocene: Bridging the geological data and modelling communities, Leeds, United Kingdom, 23–26 Aug 2022, GC10-Pliocene-45, https://doi.org/10.5194/egusphere-gc10-pliocene-45, 2022.