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.
Source
Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification
Study at a glance
- Design
- Animal / in-vitro — 80-day pH ramp experiment on live and dead Lithothamnion glaciale thalli
- N
- Thalli incubated in three pH treatments; exact thallus N not a single primary figure in stored text
- Population
- Lithothamnion glaciale coralline algae from Loch Sween, Scotland
- Outcome
- Calcification, dissolution markers, and physiology under gradual vs abrupt acidification
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
Live and dead Lithothamnion glaciale thalli from Loch Sween, Scotland, were held 80 days in control seawater (pH 8.1), a gradual drop to pH 7.7 (0.05 units per day over 10 days), or an abrupt drop (0.25 units per day over two days from day 52). Raman spectroscopy tracked bicarbonate, Mg content, and lattice disorder; calcification, photosynthesis, and respiration were also measured.
What they found
Bicarbonate (a dissolution marker) was absent in live control thalli but appeared under low and especially abrupt pH. Live algae in stable low pH calcified more by day than they dissolved at night, about twice control daytime rates, without changing photosynthesis or respiration. Dead thalli dissolved faster at low pH and could not buffer the change.
The limits
What it doesn't show
Abrupt-pH calcification was not measured. Raman differences in lattice disorder were not statistically significant. The 80-day lab mesocosms cannot capture centennial OA or grazing in the field.
Key terms
- Ocean acidification (OA)
- Long-term rise in seawater pCO2 that lowers pH; here represented by a stable drop from pH 8.1 to 7.7.
- Lithothamnion glaciale
- A high-Mg calcite red coralline alga used as a model biomineraliser.
- Abrupt pH change
- A 0.25 pH-unit per day drop over two days, mimicking CCS leaks, vents, or upwelling.
- HCO3− in the skeleton
- Raman-detected bicarbonate interpreted as early chemical breakdown of thallus calcite.
- Day–night calcification
- Live algae calcify in light; at low pH they dissolved at night but overcompensated by day.
Flashcards
Research intelligence for this paper
See its role on concept claims, tensions it is part of, placement history, and related discoveries.
Quiz yourself
The stable OA treatment targeted pH:
Common questions
Is the final pH all that matters?
No. Faster drops caused more bicarbonate (dissolution) than the same low pH reached slowly.
Can live algae compensate for OA?
Under stable low pH they up-regulated daytime calcification enough to more than offset night dissolution.
Do dead maerl beds fare as well?
No. Without an epithelium they dissolved faster and cannot repair.
Did photosynthesis fuel the extra calcification?
No significant photosynthesis or respiration change was detected.
More on Ocean acidification