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Fast pH drops damage coralline algae more than slow OA
Red coralline algae coped with a gradual drop to pH 7.7 but showed more skeletal dissolution when pH fell abruptly.
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What hypothesis did the coralline OA study test?
That faster pH change would push red coralline algae farther from background structure, and that live thalli would be buffered by their epithelium.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
Where were the algae collected?
Live and dead Lithothamnion glaciale from 7 m in Loch Sween, Scotland, in November 2009.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
What were the three pH treatments?
Control pH 8.1; low stable pH 7.7 ramped at 0.05 units/day over 10 days; low abrupt pH 8.1→7.7 at 0.25 units/day over two days from day 52.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
How long did the incubations last?
80 days.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
When did bicarbonate appear in live thalli?
Not under control pH; it appeared in increasing proportions under stable low pH and abrupt pH.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
Did all dead thalli contain bicarbonate?
Yes, including controls, indicating some dissolution even at ambient pH.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
Could live algae offset night-time dissolution at stable low pH?
Yes: they calcified significantly more by day than they dissolved at night, and slightly more than controls by day.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
How much higher were daytime calcification rates in low pH?
About twice the rate needed to maintain control-level calcification.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
Did photosynthesis or respiration change under stable low pH?
No significant differences versus controls.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
How did dead thalli respond to stable low pH?
They dissolved faster than control dead thalli.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
What is the broader implication for OA and CCS leaks?
Damage depends on rate of carbonate-chemistry change and live/dead status; service provision by dead algae is at particular risk.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified
What will determine whether biomineralisers keep providing services?
The rate at which future pCO2 enrichment occurs, not only the final pH.
Source: Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification · DOI · quote verified