13 Apr 2022
13 Apr 2022
Status: this preprint is currently under review for the journal BG.

Acidification impacts and acclimation potential of foraminifera

Daniel François1,4, Adina Paytan2, Olga Maria Oliveira de Araújo3, Ricardo Tadeu Lopes3, and Cátia Fernandes Barbosa1 Daniel François et al.
  • 1Departamento de Geoquímica, Universidade Federal Fluminense, Niterói, Brazil
  • 2Institute of Marine Sciences – University of California, Santa Cruz, USA
  • 3Federal University of Rio de Janeiro (UFRJ), Nuclear Instrumentation Laboratory, Nuclear Engineering Program/COPPE, Rio de Janeiro, Brazil
  • 4Department of Ocean Systems, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, Texel, the Netherlands

Abstract. Ocean acidification is expected to negatively affect many ecologically important organisms. Here we explored the response of Caribbean benthic foraminiferal communities to naturally discharging low-pH waters similar to expected future projections for the end of the 21st century. At low-pH (~ 7.7 pH units), low calcite saturation, agglutinated and symbiont-bearing species were relatively more abundant, indicating higher resistance to potential carbonate chemistry changes. Diversity and other taxonomical metrics declined steeply with decreasing pH despite exposure of this ecosystem for millennia to low pH conditions, suggesting that tropical foraminifera communities will be negatively impacted under acidification scenarios SSP3-7.0 and SSP5-8.5. The species Archaias angulatus, a major contributor to sediment production in the Caribbean was able to calcify at conditions more extreme than those projected for the late 21st century (7.1 pH units), but the calcified tests were of lower density than those exposed to high-pH ambient conditions (7.96 pH units), indicating that reef foraminiferal carbonate budget might decrease. Smaller foraminifera were highly sensitive to decreasing pH and our results demonstrate their potential as indicators to monitor increasing OA conditions.

Daniel François et al.

Status: open (until 16 Jun 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2022-91', Sven Uthicke, 05 May 2022 reply
  • RC2: 'Comment on bg-2022-91', Anonymous Referee #2, 25 May 2022 reply

Daniel François et al.

Daniel François et al.


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Short summary
Our analysis revealed that under the two most conservative acidification projections foraminifera assemblages did not display considerable changes. However, a significant decrease in species richness was observed when pH decrease to 7.7 pH units, indicating adverse effects under high acidification scenarios. A micro-CT analysis revealed that Archaias angulatus calcified tests of lower density at low-pH, suggesting no acclimation capacity for this species.