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.
Source
The impacts of ocean acidification, warming and their interactive effects on coral prokaryotic symbionts
Study at a glance
- Design
- Animal / in-vitro — Factorial aquarium acidification and heat stress on Galaxea and Acropora with RNA-based symbiont profiling
- N
- N=51 · 51 16S libraries; replicate fragments n=10 per experimental tank condition
- Population
- South China Sea Galaxea fascicularis and Acropora valida coral fragments
- Outcome
- Active prokaryotic symbiont communities and stress/virulence gene expression under OA and warming
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What they did
Two South China Sea corals were exposed to acidification (A), heat (H), and combined AH versus ambient (~26°C, pH ~8.1); 16S rRNA from total RNA and metatranscriptomes were compared during stress and recovery.
What they found
2.02 million 16S reads from 51 libraries. Host identity dominated community structure. Stressors still changed active communities (ANOSIM R ≥ 0.86). A. valida diversity rose under combined stress. DEGs implicated virulence, heat-shock, and reduced photosynthesis/CO2 fixation functions.
The limits
What it doesn't show
Tank pH 7.7 / 32°C is an extreme end-century pulse, not a gradual reef trajectory; RNA from fragments does not equal colony mortality on reefs.
Key terms
- Ocean acidification (A)
- Lowered seawater pH from elevated CO2 (here toward ~7.7).
- Warming (H)
- Heat stress to 32°C versus ambient ~26°C.
- Prokaryotic symbionts
- Active bacteria/archaea associated with coral holobionts.
- Galaxea fascicularis
- Massive, relatively stress-tolerant coral.
- Acropora valida
- Branching, stress-sensitive coral.
Flashcards
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Control tanks were about:
Common questions
Control tank conditions?
~26°C and pH ~8.1.
Heat target?
32°C.
Did host or environment dominate microbes?
Host specificity clustered communities more than treatments.
Functional shift?
More virulence/stress genes; photosynthesis/C-fixation DEGs declined.
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