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Ecological Intelligence / Subject

coral reefs

Peer-reviewed

Two ESA-listed corals around American Samoa occupy different environmental niches—and the models are only moderately predictive

Evidence
Peer-reviewed
Geography
Tutuila, American Samoa
System
Coral reef

WHAT THE EVIDENCE SAYS

Researchers built ensemble MaxEnt models for Acropora globiceps and Isopora crateriformis using multi-source occurrence records from 2007–2025, open environmental data and predictors including thermal stress, water clarity, wind variability, seafloor structure and land-based stressors. Models trained through 2024 were evaluated against independent 2025 observations. The two listed corals showed distinct habitat associations, demonstrating that closely related recovery targets should not be assumed to share the same environmental niche.

WHY IT MATTERS / OUR READ

For recovery planning, the value is in separating species-specific habitat hypotheses instead of managing ‘listed coral habitat’ as a single category. Open biodiversity and satellite datasets can help prioritize survey effort, but the model should be used to ask where to verify habitat—not to replace field observation.

CAVEATS / UNCERTAINTY

These are presence-only relative-suitability models in a data-limited setting, not abundance, demographic or survival models. Forecast discrimination was moderate rather than definitive, occurrence records came from multiple survey sources, and open environmental layers carry their own spatial and temporal uncertainty.

SOURCE

Scientific Reports — primary study
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Presence-only models separated the habitat associations of Acropora globiceps and Isopora crateriformis and were tested against independent 2025 observations to support monitoring and recovery planning.

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Peer-reviewed Global

More coral does not fully rescue fish richness when algae also gains ground

Evidence
Peer-reviewed
Geography
Global coral-reef dataset
System
Coral reefs

WHAT THE EVIDENCE SAYS

Using a global reef dataset spanning 2006–2023, researchers tested how low-lying algae and macroalgae altered the relationship between live hard-coral cover and fish species richness. Both algal groups weakened the positive coral–fish richness relationship. Low-lying-algae effects were evident where coral cover was below about 45%, while macroalgal effects persisted until roughly 65% coral cover. Sensitivity also varied with fish diet and body size.

WHY IT MATTERS / OUR READ

Coral cover is not a sufficient condition metric by itself. Two reefs with similar coral cover can carry different fish-diversity prospects if algal state and functional composition differ.

CAVEATS / UNCERTAINTY

The reported coral-cover values are statistical context thresholds from an observational global dataset, not universal management trigger points. Species richness does not capture abundance, biomass or ecosystem function, and associations do not establish that reducing algae alone would restore fish richness.

SOURCE

Conservation Biology — primary study
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A global 2006–2023 dataset found low-lying algae weakened the coral-cover relationship below about 45% coral cover, while macroalgal effects persisted to about 65%.

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Government data

NOAA has completed a new Pacific coral baseline built from 3-D imagery, fish surveys and water sampling

Evidence
Government data
Geography
American Samoa and Pacific Islands Heritage Marine National Monument
System
Tropical coral reefs and long-term reef monitoring

WHAT THE EVIDENCE SAYS

NOAA Fisheries reports completion of its 2026 Pacific coral surveys across American Samoa and the Pacific Islands Heritage Marine National Monument. Teams used repeated fish surveys, benthic photoquadrats, thousands of images for three-dimensional reef models and water sampling across remote islands and atolls. The resulting data will feed the National Coral Reef Monitoring Program after processing and analysis.

WHY IT MATTERS / OUR READ

For ecological intelligence, the notable part is the combination of repeatable biological surveys with spatially explicit 3-D habitat reconstruction. That creates a stronger baseline for detecting structural change than simple cover metrics alone and should become increasingly useful as bleaching, storms and local disturbance interact.

CAVEATS / UNCERTAINTY

This is a monitoring-completion report, not an ecological outcome paper. NOAA has not yet published the full analyzed 2026 condition results, so no trend or management conclusion should be inferred from the survey effort itself.

SOURCE

NOAA Fisheries
View original evidence ↗

The 2026 National Coral Reef Monitoring Program surveyed American Samoa and remote Pacific monuments; the important result today is the monitoring architecture, not a reef-status verdict that has not yet been analyzed.

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