Ocean acidification
Lower pH kills spirorbids but favors sponges
Open access · cc by · source: Europe PMC
A 0.2-unit drop in seawater pH over 100 days thins calcareous tube worms and algae while sponges and some sea squirts increase.
Study at a glance
- Design
- Animal / in-vitro — 100-day flow-through aquarium experiment comparing biofouling at pH 7.9 vs 7.7
- N
- N=50 · Spirorbid counts analysed with n=50 quadrats/surfaces; algal scores n=11
- Population
- Ria Formosa biofouling communities on pipes, HDPE, limestone, and tank walls
- Outcome
- Live spirorbid density, mortality, and shifts toward sponges/ascidians under acidification
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
At pH 7.7, live spirorbids fell from 11.1 to 2.0 per 10 cm² and 72.8% of tubes were dead (versus 23.3% in controls). Sponges rose 2.5-fold and Molgula ascidians fourfold. New spirorbid settlement dropped several-fold on all surfaces; algal films were thinner (score 1.8 vs 4.4).
Methodology
Researchers held Ria Formosa biofouling communities at pH 7.9 versus 7.7 for 100 days in a flow-through aquarium, tracking established assemblages on pipes and new colonization of HDPE, limestone tiles, and tank walls.
Limitations
The pH drop (0.2) is milder than some 2100 projections, tanks were at a fixed 23°C, and 100 days cannot capture century-scale evolution or open-coast food webs.
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.
This library holds 6 empirical papers on ocean acidification with measured outcomes rather than reviews.
Evidence for the claim as stated.
A 0.2-unit drop in seawater pH over 100 days thins calcareous tube worms and algae while sponges and some sea squirts increase.
Evidence for the claim as stated.
Lab pH treatments and coastal variability are not the same as open-ocean century-scale change.
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.
Lab pH treatments and coastal variability are not the same as open-ocean century-scale change.
Related papers in this topic
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