Claim

In a 39-day North Sea mesocosm experiment, phytoplankton bloom dynamics were largely unaffected by alkalinity additions up to about 700 micromoles per kilogram, whereas additions of at least about 900 delayed bloom development by 6 to 9 days and reduced some particulate organic matter components.

Type QUANTITATIVE · truth-evaluable: yes · status at snapshot: ACTIVE · created seq 19554

45 words; atomic claims are usually under 25a conjunction joins clauses that may be separately evaluablea comma-separated series may list several propositions

Referenced 146 times: checked 2, looked up by assistants 1, viewed 108, shared 35. A count of attention, not evidence.

Topics

Climate · 1efd24fe Earth science · 1efd24fe

Assessment

Supported

Score: 0.8787 under ledger-default@0.3.0 at snapshot 27745

2 of 4 review checks done · 1 counted · 1 by the author only

2 independent evidence lineages · review checks 1 of 4 · stability MEDIUM

Main unresolved issue: 7 counted evidence items have no independence review; repeats of one origin may be counted as several coverage:25dbbcc3-c87e-8dd1-b35e-d4d636d7f20d

Not yet independently audited.Evidence reviewed so far supports this claim, but only 1 of 4 review checks has been done.A quoted passage from geomar.de and nature.com was not found on the page when Galedra fetched it.

Related: NARROWS incoming: Supported

Why?

Strongest counted support: The abstract directly reports the mesocosm duration, alkalinity thresholds, bloom delay, and particulate-organic-phosphorus reduction. weight 1.800000 evidence

Suppressed as dependent: The passage directly reports the 39-day mesocosm experiment, low-to-moderate no-effect range, high-alkalinity bloom delay, and particulate-organic-phosphorus reduction.

Review gaps: qualifiers reviewed, opposing search done, independence reviewed

What would most change this: One independent, direct measurement that contradicts this claim would move it from Supported to Unresolved.

Hide calculation

0.8787 under ledger-default@0.3.0 at snapshot 27745 · state Supported · Review checks: 1 of 4 · stability MEDIUM · 7 sources, 2 independent lineages

Model ledger-default@0.3.0 (the default model, not the answer) · snapshot 27745 · trace sha256:6986f07b645721be0479e624e696ed3147f78bda5a4ed00af03bd6d3f9135136

Last changed at entry seq 25493; nothing logged since has borne on this claim.

How the number was reached

Each counted link is weighed by multiplying the factors the model declares; a factor it does not declare is not shown. Every factor name below links to what that number means.

Link	Working	Weight	Counted as
a75e5afa qualify	relevance DIRECT 2.0 × observation DIRECT_TEXT 0.9 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	1.800000	0.000000 (non directional)
05e63b4c support	relevance DIRECT 2.0 × observation DATASET_RESULT 0.9 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	1.800000	1.800000
0593b460 qualify	relevance DIRECT 2.0 × observation DATASET_RESULT 0.9 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	1.800000	0.000000 (non directional)
49faab06 support	relevance WEAK 0.2 × observation DIRECT_TEXT 0.9 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	0.180000	0.180000
8069bb3a qualify	relevance DIRECT 2.0 × observation DIRECT_TEXT 0.9 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	1.800000	0.000000 (non directional)
d514e2b1 qualify	relevance DIRECT 2.0 × observation DIRECT_TEXT 0.9 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	1.800000	0.000000 (non directional)
86fe97f1 support	relevance DIRECT 2.0 × observation DIRECT_TEXT 0.9 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	1.800000	0.000000 (dependent strongest only, kept 05e63b4c)

prior 0.50 → log-odds 0.000000 + 1.980000 (the counted weights) = 1.980000 → probability 0.8787

Under neighbouring settings of the same model: 0.8000 to 0.9292, a spread of 0.1292.

Half-even rounding, six places for weights and four for the probability. The same inputs under the same model reproduce this exactly; that is what the trace hash above is for. How a score is worked out explains every factor, why it is there, and what the model sets it to.

Your view

Registered views

Nobody has registered a view yet.

Registered views are personal belief, not evidence: they never change Galedra's assessment. Affiliations are self-declared and shown only for groups of 5 or more.

Checked as part of

Statements this claim was broken out of. The claim is scored on its own; a statement's reading only counts its claims.

“In a 39-day North Sea mesocosm experiment, phytoplankton bloom dynamics were largely unaffected by alkalinity additions up to about 700 micromoles per...” · 1 claim · 29 September 2026
“In a 39-day North Sea mesocosm experiment, phytoplankton bloom dynamics were largely unaffected by alkalinity additions up to about 700 micromoles per...” · 1 claim · 29 September 2026

Evidence for

The abstract directly reports the mesocosm duration, alkalinity thresholds, bloom delay, and particulate-organic-phosphorus reduction.

From Spring phytoplankton bloom dynamics reveal thresholds of ocean alkalinity enhancement in the North Sea Read 2026-09-29 Relevance DIRECT Steps 0 Counted
The passage directly reports the 39-day mesocosm experiment, low-to-moderate no-effect range, high-alkalinity bloom delay, and particulate-organic-phosphorus reduction.

From Spring phytoplankton bloom dynamics reveal thresholds of ocean alkalinity enhancement in the North Sea Read 2026-09-29 Relevance DIRECT Steps 0 Counted
Independent GEOMAR coverage of an earlier 33-day mesocosm study reports stable plankton communities under moderate CO2-equilibrated alkalinity enhancement while explicitly limiting generalization to other marine environments and stronger perturbations.

From How do marine food webs respond to increasing alkalinity? Read 2026-09-29 Relevance WEAK Steps 0 Counted

Contextual corroboration only; it does not reproduce the newer North Sea threshold or bloom-delay estimate.

Evidence against

None.

Qualifications

The study used twelve 6-m³ mesocosms over 39 days in spring 2023, with immediate and delayed dilution treatments.

From Spring phytoplankton bloom dynamics reveal thresholds of ocean alkalinity enhancement in the North Sea Read 2026-09-29 Relevance DIRECT Steps 0 Counted

Adds mesocosm count, volume, season/year, and dilution design.
The site was temperate-eutrophic German North Sea water at Helgoland, typically diatom-dominated during the experiment season.

From Spring phytoplankton bloom dynamics reveal thresholds of ocean alkalinity enhancement in the North Sea Read 2026-09-29 Relevance DIRECT Steps 0 Counted

Limits ecological context to temperate-eutrophic, diatom-dominated Helgoland water.
Biological thresholds were based on measured post-mixing D7 alkalinity rather than only target additions.

From Spring phytoplankton bloom dynamics reveal thresholds of ocean alkalinity enhancement in the North Sea Read 2026-09-29 Relevance DIRECT Steps 0 Counted

Clarifies that biological thresholds use measured post-mixing D7 values.
The authors caution that reduced-mixing deployment scenarios may have a more constrained ecological safe operating space.

From Spring phytoplankton bloom dynamics reveal thresholds of ocean alkalinity enhancement in the North Sea Read 2026-09-29 Relevance DIRECT Steps 0 Counted

Limits transfer to reduced-mixing deployment scenarios.

Suppressed as dependent

Evidence	Group	Kept instead
c96047e3		05e63b4c

Inferences

Concluded from

None.

Used as a premise in

None.

An inference is interpretation, not evidence: it never changes the assessment of its conclusion. Each premise is a claim with its own evidence.

Threads

None. Threads are for disagreements about how a determination was made — a statement whose figures are not in the passage it rests on, two sources that may share an origin. Something about the world belongs in the evidence above.

Claim edges

From	Relationship	To
fbd6a48e	NARROWS	36d7f20d

Review checklist

Review checks: 1 of 4

2 checks by this claim's own author, alongside the independent review above. 1 QUALIFIER CHECK · 1 EVIDENCE VERIFICATION. A check by the person who recorded a claim does not raise its review coverage.

Check	Done	By
qualifiers reviewed	no
opposing search done	no
independence reviewed	no
primary source reviewed	yes	a75e5afa, 05e63b4c, 0593b460, 8069bb3a, d514e2b1, 86fe97f1

Summary

Supported. The main support is: The abstract directly reports the mesocosm duration, alkalinity thresholds, bloom delay, and particulate-organic-phosphorus reduction. 473400a7

1 further item repeats the same origin and is not independent evidence. c96047e3

Qualifier: The authors caution that reduced-mixing deployment scenarios may have a more constrained ecological safe operating space. f14343c2

Qualifier: The study used twelve 6-m³ mesocosms over 39 days in spring 2023, with immediate and delayed dilution treatments. 2ef54b84

Qualifier: The site was temperate-eutrophic German North Sea water at Helgoland, typically diatom-dominated during the experiment season. 7f47fe19

Qualifier: Biological thresholds were based on measured post-mixing D7 alkalinity rather than only target additions. 2007ab20

Generated by stub-v0.1; every sentence cites graph ids.

Contribution history

seq	event	detail
19554	APPENDED
19555	ACCEPT	AUTOMATIC_AFTER_VALIDATION
19560	LINK_EVIDENCE	by 1efd24fe (accepted)
19568	TASK_RESULT	by 1efd24fe (accepted)
19708	LINK_EVIDENCE	by 1efd24fe (accepted)
25492	TASK_RESULT	by 1efd24fe (accepted)

Score trace

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