Preprints
https://doi.org/10.5194/esd-2023-24
https://doi.org/10.5194/esd-2023-24
04 Sep 2023
 | 04 Sep 2023
Status: a revised version of this preprint is currently under review for the journal ESD.

Physiological and ecological tipping points caused by ocean acidification

Christopher Cornwall, Steeve Comeau, and Ben Harvey

Abstract. Ocean acidification is predicted to cause profound shifts in many marine ecosystems by impairing the ability of calcareous taxa to calcify and grow, and by influencing the photo-physiology of many others. In both calcifying and non-calcifying taxa, ocean acidification could further impair the ability of marine life to regulate internal pH, and thus metabolic function and/or behaviour. Identifying tipping points at which these effects will occur for different taxa due to the direct impacts of ocean acidification on organism physiology is difficult and they have not adequately been determined for most taxa, nor for ecosystems at higher levels. This is due to the presence of both resistant and sensitive species within most taxa. However, calcifying taxa such as coralline algae, corals, molluscs, and sea urchins appear to be most sensitive to ocean acidification. Conversely, non-calcareous seaweeds, seagrasses, diatoms, cephalopods, and fish tend to be more resistant, or even benefit from the direct effects of ocean acidification. While physiological tipping points of the effects of ocean acidification either do not exist or are not well defined, their direct effects on organism physiology will have flow on indirect effects. These indirect effects will cause ecologically tipping points in the future through changes in competition, herbivory and predation. Evidence for indirect effects and ecological change is mostly taken from benthic ecosystems in warm temperate–tropical locations in situ that have elevated CO2. Species abundances at these locations indicate a shift away from calcifying taxa and towards non-calcareous at high CO2 concentrations. For example, lower abundance of corals and coralline algae, and higher covers of non-calcareous macroalgae, often turfing species, at elevated CO2. However, there are some locations where only minor changes, or no detectable change occurs. Where ecological tipping points do occur, it is usually at locations with naturally elevated pCO2 concentrations of 500 μatm or more, which also corresponds to just under that concentrations where the direct physiological impacts of ocean acidification are detectable on the most sensitive taxa in laboratory research (coralline algae and corals). Collectively, the available data support the concern that ocean acidification will most likely cause ecological change in the near future in most benthic marine ecosystems, with tipping points in some ecosystems at as low as 500 μatm pCO2. However, much more further research is required to more adequately quantify and model the extent of these impacts in order to accurately project future marine ecosystem tipping points under ocean acidification.

Christopher Cornwall, Steeve Comeau, and Ben Harvey

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esd-2023-24', Anonymous Referee #1, 06 Oct 2023
    • AC1: 'Reply on RC1', Christopher Cornwall, 14 Dec 2023
    • AC3: 'New figure', Christopher Cornwall, 17 Dec 2023
  • RC2: 'Comment on esd-2023-24', Anonymous Referee #2, 01 Nov 2023
    • AC2: 'Reply on RC2', Christopher Cornwall, 14 Dec 2023
Christopher Cornwall, Steeve Comeau, and Ben Harvey
Christopher Cornwall, Steeve Comeau, and Ben Harvey

Viewed

Total article views: 728 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
516 184 28 728 13 15
  • HTML: 516
  • PDF: 184
  • XML: 28
  • Total: 728
  • BibTeX: 13
  • EndNote: 15
Views and downloads (calculated since 04 Sep 2023)
Cumulative views and downloads (calculated since 04 Sep 2023)

Viewed (geographical distribution)

Total article views: 693 (including HTML, PDF, and XML) Thereof 693 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Latest update: 21 Feb 2024
Download
Short summary
Here we demonstrate that ocean acidification is predicted to cause profound shifts in many marine ecosystems by impairing the ability of calcareous taxa to grow, and by influencing the photosynthesis of many others. At naturally elevated CO2 sites, species shift away from calcifying taxa and towards non-calcareous species. Ocean acidification will most likely cause ecological change in the near future in most benthic marine ecosystems, with some taxa predicted to be impacted before 2050.
Altmetrics