Concept
Ocean acidification
Ocean acidification is the drop in seawater pH and carbonate saturation as CO2 dissolves, tested on calcifiers, reefs or coastal chemistry.
It is the marine half of the carbon problem undergraduates meet in environmental science.
Evidence
What the evidence shows
Drawn from 6 studies in this library. Each finding starts with a plain-language takeaway, then the denser detail. Supports means evidence for a finding; Challenges means evidence against a stated position; Qualifies marks scope with a short note on each study’s contribution. Challenged positions are labeled — they are not findings.
This library holds 6 empirical papers on ocean acidification with measured outcomes rather than reviews.
After 6 days at pH ~7.7 and 32°C, Galaxea and Acropora RNA-based symbionts shifted and virulence/stress genes rose, changes that often persisted 9 days after stressors ended.
A 0.2-unit drop in seawater pH over 100 days thins calcareous tube worms and algae while sponges and some sea squirts increase.
Six weeks of ocean acidification on crustose coralline algae halved Acropora settlement, but larvae still settled on ambient-conditioned CCA even at low pH.
Selectively bred Saccostrea glomerata keep more ordered calcite and can use different DIC pathways than wild-type oysters in acidified Australian estuaries.
Open questions
Tensions and limits
Some items are genuine disagreements on the same question. Others mark different assays, populations, or outcomes — limits on how far one study travels — not a forced fight between papers.
Lab pH treatments and coastal variability are not the same as open-ocean century-scale change.
Study Role Design N Population Outcome OA and heat push coral microbes toward pathogens Supports Animal / in-vitroFactorial aquarium acidification and heat stress on Galaxea and Acropora with RNA-based symbiont profiling N=51 · 51 16S libraries; replicate fragments n=10 per experimental tank condition South China Sea Galaxea fascicularis and Acropora valida coral fragments Active prokaryotic symbiont communities and stress/virulence gene expression under OA and warming Lower pH kills spirorbids but favors sponges Supports Animal / in-vitro100-day flow-through aquarium experiment comparing biofouling at pH 7.9 vs 7.7 N=50 · Spirorbid counts analysed with n=50 quadrats/surfaces; algal scores n=11 Ria Formosa biofouling communities on pipes, HDPE, limestone, and tank walls Live spirorbid density, mortality, and shifts toward sponges/ascidians under acidification
Common misconceptions
Ocean acidification dissolves every shell equally.
Sensitivity depends on taxon, life stage and the rate of pH change.
Exam-style questions
Short-answer questions that ask you to explain or compare, not recall.
What does ocean acidification mean in this library?
Ocean acidification is the drop in seawater pH and carbonate saturation as CO2 dissolves, tested on calcifiers, reefs or coastal chemistry.
Name one empirical finding from the ocean acidification papers.
After 6 days at pH ~7.7 and 32°C, Galaxea and Acropora RNA-based symbionts shifted and virulence/stress genes rose, changes that often persisted 9 days after stressors ended.
What is a limit of ocean acidification evidence here?
Lab pH treatments and coastal variability are not the same as open-ocean century-scale change.
The studies
6 studies in this library bear on Ocean acidification, ordered by citations.
- Acidified algae, not larvae, block coral settlement
Six weeks of ocean acidification on crustose coralline algae halved Acropora settlement, but larvae still settled on ambient-conditioned CCA even at low pH.
- 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.
- Warming and acidification squeeze coral habitat
Modeled coral-reef suitability falls about 27–30% in shallow water by 2070, worst in the Western Pacific Warm Pool.
- Lower pH kills spirorbids but favors sponges
A 0.2-unit drop in seawater pH over 100 days thins calcareous tube worms and algae while sponges and some sea squirts increase.
- Bred oysters switch shell carbon under acidification
Selectively bred Saccostrea glomerata keep more ordered calcite and can use different DIC pathways than wild-type oysters in acidified Australian estuaries.
- OA and heat push coral microbes toward pathogens
After 6 days at pH ~7.7 and 32°C, Galaxea and Acropora RNA-based symbionts shifted and virulence/stress genes rose, changes that often persisted 9 days after stressors ended.
Learn alongside
Change log
What changed
Dated edits to this page's evidence: studies added or removed from a claim, claims added or withdrawn, and new explanations tagged here. Rewordings are not listed.
- Concept page published