Mauritius - Aquarium / Big Rock
Part of the regional summary: Mauritius
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Southern Mauritius (NOAA CRW virtual station)Two adjacent sites off Flic en Flac dived together, built from huge volcanic boulders and rock spurs separated by pavement and dead coral framework, mostly covered in turf, brown algae, and coralline crust. Coral is sparse (massive colonies, small branching colonies, and one large table coral), and highlights included a day octopus and a resting sea turtle.
Deux sites adjacents au large de Flic en Flac, plongés ensemble, constitués d'énormes blocs volcaniques et d'éperons rocheux séparés par de la dalle et une charpente corallienne morte, majoritairement recouverte de gazon algal, d'algues brunes et de croûtes corallines. Le corail est rare (colonies massives, petites colonies branchues et un grand corail de table), et un poulpe diurne et une tortue de mer au repos figurent parmi les observations marquantes.
Traduction par IA de ce résumé ; la version anglaise fait foi.
Twenty independent survey stations shown with the program’s logo — click one to see how far it is from this site.
One other CRD dive site with its own page within 5 km shown in orange — click a marker to open its page.
12 of the 46 photographs on this page are shown beside the text that discusses them under "Site description" below.
Site description
Setting
Two adjacent sites dived together off Flic en Flac on the west coast: huge volcanic boulders and rock spurs separated by low pavement and dead coral framework, most of it covered in turf, foliose brown algae, and coralline algae (e.g., Image 2, Image 4, Image 6, Image 7, Image 11, Image 18).
General benthic features
Manually scored point-count cover was 14% hard coral, dominated by massive dome-shaped colonies, small branching colonies, a large table coral, and scattered encrusting colonies (e.g., Image 3, Image 9, Image 13).
Coral cover
- Reference: Mayfield et al. (2026, Platax), Table 3 (manuscript in preparation)
- CoralNet submission package
- Coral cover: 14% — Anderson Mayfield's manual point count of the photographs (Mayfield et al. 2026 Platax Table 3).
Stressors
No widespread bleaching was evident. A few colonies were bleached, and Anderson's own point annotations label them bleached hard coral: a small branching colony, cream to stark white beside a tan colony of the same form (e.g., Image 51), and a table colony with a pale cream-to-white upper surface (e.g., Image 37).
No crown-of-thorns starfish (COTS) or other corallivores were evident.
Fish and other fauna
Highlights included a large day octopus, a resting sea turtle, a phyllidiid nudibranch, and a pair of double-barred goatfish (e.g., Image 12).
Comparisons with other data
Pisternick et al. 2020 (PANGAEA) surveyed a nearby station (FEF_C_9_1 (Flic en Flac, Control)) in 2018, 0.02 km from the pin. Within 5 km, twenty independent stations recorded hard coral cover between 2018 and 2019: seventeen by benthic survey, station-year means of 0.0–29%, and three by MERMAID bleaching-protocol quadrats, station-year means of 13–30%; the nearest, Pisternick et al. 2020 (PANGAEA) at FEF_C_9_1 (Flic en Flac, Control), 0.02 km away, read 0.0% in 2018.
CV model comparison
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That convention would raise every Mauritius site by 0–3.7 pp. The Claude row is the manuscript's Claude (with image context) value, scored on the same frames as the manual count; one of its five sets of context images had been seen before, so it is not fully blind. Anemone Garden is anemone habitat rather than coral reef; its manual value stands but carries no error term. CoralSCOP (SAM-based mask-sum), edited photos: n/a — no edited copies exist; all 347 Mauritius photographs are unedited.| Method | Hard coral cover (%) | Photos (n) ± SE |
|---|---|---|
| Manual (reference) | 14.0 | |
| CoralNet | 7.0 | n = 40 |
| Coralscapes v1 | 8.2 | |
| CoralSCOP | 13.0 | n = 40 |
| DINOv3 | 15.3 | n = 40 |
| Claude (context) | 8.3 | n = 40 |
The four computer-vision methods differ by 8.3 pp (7.0–15.3%) and read within 7.0 pp of the manual point count (14.0%); the headline is the manual point count because a person's point count of the site's photographs is the reference the models are measured against.
The Coralscapes v1 row is shown for reference only, outside this comparison.
See a more detailed, stand-alone version of this table.
Independent surveys nearby
| Agency / program | Year(s) | Stations / distance | Link |
|---|---|---|---|
| Pisternick et al. 2020 (PANGAEA) | 2018 | 17 stations, 0.02–1.59 km | Records ↓ |
| WCS Kenya / University of Mauritius via MERMAID (MERMAID bleaching-protocol quadrats) | 2019 | 3 stations, 1.29 km | Records ↓ |
Coral Reef DiagnosticsWithin 5 km, 20 independent survey stations recorded hard coral cover in 20 surveys between 2018 and 2019. The most recent nearby survey is from 2019, so these values predate recent heat stress. This site's own estimate (14%) sits within the range of these station-year means excluding MERMAID bleaching-protocol quadrats (0.0–29%); the methods differ, so the comparison is context, not a like-for-like test. Quadrats up to 2 km away read 13–30%.
Collected by other programs using different methods (MERMAID is a data platform: each MERMAID row names the organization that did the survey, and its method is in the row's hover text), so these are context for the figures above, not a like-for-like comparison. Where a station was surveyed more than once, the cell shows either the range of its values or, as a single value, the mean of surveys made in one year. Station names are not dive-site names.
Show all 20 independent surveys
Data & links
- CoralNet image repository for this region ↗
- Photo portfolio ↗
- Coral Reef Diagnostics page for this area ↗
All images from Coral Reef Diagnostics. Data are from Coral Reef Diagnostics and the organizations named in the data sources above.
© Coral Reef Diagnostics.