Ocean acidification
Fast pH drops damage coralline algae more than slow OA
Open access · cc by · source: Europe PMC
Red coralline algae coped with a gradual drop to pH 7.7 but showed more skeletal dissolution when pH fell abruptly.
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.
Key findings
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.
Methodology
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.
Limitations
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.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Live and dead Lithothamnion glaciale thalli 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). 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. Abrupt-pH calcification was not measured.
Evidence for the claim as stated.
These mesocosms do not test one carbon-cycle claim. Litter tanks show aromaticity cutting bacterial production 14.5% with lake-colour differences in respiratory cost versus photo-oxidation. Canopy ¹⁵N recovers 3–4× more tracer in wood than soil targeting but does not scale to forest C stocks. Everglades inoculum effects on trunk diameter appear only under unconstrained flooding. Coralline algae are more sensitive to the rate of the pH drop than to low pH as a level, and live thalli at stable pH 7.7 increased daytime calcification. 'Mesocosms show carbon or OA effects' is not a single result.
Evidence for the claim as stated.
Live versus dead material reverses the practical inference at low pH. Live Lithothamnion in stable low pH calcified more by day (~twice control) without changing photosynthesis or respiration, whereas dead thalli dissolved faster and could not buffer. Using only dead-skeleton dissolution rates would miss the live buffering the authors measured — and they still did not measure calcification in the abrupt treatment.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
These mesocosms do not test one carbon-cycle claim. Litter tanks show aromaticity cutting bacterial production 14.5% with lake-colour differences in respiratory cost versus photo-oxidation. Canopy ¹⁵N recovers 3–4× more tracer in wood than soil targeting but does not scale to forest C stocks. Everglades inoculum effects on trunk diameter appear only under unconstrained flooding. Coralline algae are more sensitive to the rate of the pH drop than to low pH as a level, and live thalli at stable pH 7.7 increased daytime calcification. 'Mesocosms show carbon or OA effects' is not a single result.
Live versus dead material reverses the practical inference at low pH. Live Lithothamnion in stable low pH calcified more by day (~twice control) without changing photosynthesis or respiration, whereas dead thalli dissolved faster and could not buffer. Using only dead-skeleton dissolution rates would miss the live buffering the authors measured — and they still did not measure calcification in the abrupt treatment.
Related papers in this topic
Same topic cluster — not a recommendation engine.