Part of the regional summaries: Chagos Archipelago - Salomon / Blenheim / Speakers Bank and Chagos Archipelago
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Chagos Archipelago, UK (NOAA CRW virtual station)A lagoonal patch reef inside Salomon, leeward on Anderson's field sheet (dived to 20.5 m; station CTD-cast midpoint 30.7°C), almost fully occupied (60% coral, 1.3% bare substrate) with 33 genera, including abundant Lobophyllia and free-living mushroom corals. Several sharply white colonies stand out amid the dense, high-relief mix (12% bleached). Surveyed on the Living Oceans Foundation's Global Reef Expedition.
CTD-cast midpoint of 29.9–31.4°C
Nine independent survey stations shown with the program’s logo — click one to see how far it is from this site.
Eleven other CRD dive sites with their own pages within 5 km shown in orange — click a marker to open its page.
🗺 Detailed map of the Global Reef Expedition dive sites, Salomon Atoll, Chagos (Khaled bin Sultan Living Oceans Foundation; opens in a new window)
4 of the 19 photographs on this page are shown beside the text that discusses them under "Site description" below.
Site description
Setting
BISA88 is a lagoonal patch reef inside Salomon atoll, leeward on Anderson's field sheet, surveyed 23 April 2015 on a dive to 20.5 m (station CTD-cast midpoint 30.7°C).
General benthic features
Thirty-three genera were recorded, with Acropora, Montipora, Porites, and Lobophyllia sharing the assemblage, alongside free-living mushroom corals. The four depth strata change leading genus at every stratum — Acropora, then Lobophyllia, then Porites where cover peaks at 65%, then Montipora holding 60% of the coral where cover falls away.
Coral cover
- Reference: Mayfield & Dempsey (2026)
- CoralNet submission package
- Formal transects recorded 60% coral cover against 31% algae, on a reef almost fully occupied, with bare substrate at just 1.3% (e.g., Image 3, Image 4).
- Transect mean 60 ± 2.8% SE (n = 16 transects; Living Oceans Foundation per-transect benthic data); the headline above is this all-transect mean, and the published station value, which weights each depth equally, is 57% (Mayfield & Dempsey 2026, Oceans, suppl. S1).
Stressors
Published bleaching is 12%, and the photographs show several sharply white colonies amid dense, high-relief mixed architecture (e.g., Image 5, Image 7).
No crown-of-thorns or disease signs were identified in any of the 19 frames. The bleaching percentage is a computer vision figure: CoralNet annotation of the informal survey images, not a diver's field estimate (Mayfield & Dempsey 2026, suppl. S1). Anderson's sampling sheet records 13 colonies sampled here at 5.9–20.4 m: eight Pocillopora acuta by RFLP; five Seriatopora hystrix by field call; the condition notes run from healthy to 100% bleached, with some partly dead colonies. Pocillopora acuta colonies from this archipelago were analyzed in Thomas et al. (2026, Global Ecology and Biogeography 35:e70305, https://doi.org/10.1111/geb.70305). The Living Oceans Foundation transects here recorded 0.2% cyanobacteria and 0.2% recently dead coral.
Comparisons with other data
Apart from the Living Oceans Foundation survey shown here, we found no other surveys at this site as of 2026. Within 5 km, nine independent stations recorded station-year means of 6.8–63% hard coral cover between 2006 and 2020; the nearest, Sheppard et al. (2008) at Salomon, 1.27 km away, read a mean of 32% in 2006.
Other notes
Aspect follows Anderson's field sheet (LOF fellowship 2016 workbook: 'lagoonal patch reef', 'leeward'); the expedition's 933-site table classes the station as 'protected' (patch reef). Esri World Imagery (no LOF habitat map covers Salomon atoll; the LOF Chagos habitat map covers only Peros Banhos) puts the pin on a small patch reef near the middle of the Salomon lagoon, consistent with the sheet.
CV model comparison
More info
Those are point counts on the photographs; this is a diver swimming a transect. The models and the reference never saw the same thing. ⚠ SITE-LEVEL ONLY. None of the Chagos photographs (2,500 frames across all stations) can be matched to a transect taken within 200 m, so transect-vs-image comparisons use site means, never individual frames. The transect value is the mean of all of this station's own transects in the expedition's per-transect benthic data. The transect is THE coral-cover value for this site and stands alone. The rows below it are a methods comparison only: no computer-vision value is averaged with it, feeds the headline, or carries over to the site's cover figure.| Method | Hard coral cover (%) | Photos (n) ± SE |
|---|---|---|
| Transect mean (all transects) | 59.9 | |
| CoralNet | 45.8* | n = 13 · SE 5.8 |
| In-house DINOv3 | 54.1* | n = 13 · SE 5.8 |
| CoralSCOP edited | 43.4* | n = 13 · SE 4.1 |
| Claude | 42.7* | n = 13 · SE 4.8 |
The four computer-vision methods disagree by 11.4 pp (42.7–54.1%) and read 5.8–17.2 pp below the in-water transect (59.9%); the headline is the in-water transect because a diver transect is independent of the photographs.
*Based on only 13 reef-habitat photos; this estimate is less certain.
See a more detailed, stand-alone version of this table.
Independent surveys nearby
| Agency / program | Year(s) | Stations / distance | Link |
|---|---|---|---|
| Lange et al. (2021) | 2006–2020 | 2 stations, 2.79–2.91 km | Records ↓ |
| Sheppard et al. (2008) | 2006 | 1 station, 1.27 km | Records ↓ |
| Spalding et al. (2025) | — | 1 station, 3.58 km | Records ↓ |
| XL Catlin Seaview Survey | 2015 | 6 stations, 2.15–4.83 km | Records ↓ |
LOF Global Reef ExpeditionYear-average (illustrative only, programs differ)Within 5 km, 9 independent survey stations recorded hard coral cover in 21 records between 2006 and 2020. Of the 2 stations surveyed in more than one year, 2 declined (by 17–27 points) between their first and latest surveys. Two stations share the longest span (2006–2020); one, Salomon Atoll (Lange et al. 2021, 2.79 km away), went from 48% in 2006 to 21% in 2020. The most recent nearby survey is from 2020, so these values predate recent heat stress. This site's own estimate (60%) sits 28 points above the one survey station up to 2 km away (32%); the methods differ, so the comparison is context, not a like-for-like test. One further row in the table has no survey date, so it is listed but not part of this summary.
Collected by other programs using different methods (the XL Catlin Seaview Survey uses photo-transects with automated image annotation), 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.
| Agency | Site / location | Date | Hard coral cover (%) | Distance | Link |
|---|---|---|---|---|---|
| Sheppard et al. (2008) | Salomon | 2006 | 32% (5 records) | 1.27 km | doi:10.3354/meps07436 |
| Lange et al. (2021) | Salomon Atoll | 2006–2020 | 6.8–63% (range of yearly means; 5 records) | 2.79 km | doi:10.1007/s00338-021-02184-w |
| Lange et al. (2021) | Salomon Atoll | 2006–2020 | 9.9–43% (range of yearly means; 5 records) | 2.91 km | doi:10.1007/s00338-021-02184-w |
| XL Catlin Seaview Survey | transect 36013 | 2015 | 28% | 2.15 km | doi:10.14264/uql.2019.930 |
| XL Catlin Seaview Survey | transect 36018 | 2015 | 22% | 2.26 km | doi:10.14264/uql.2019.930 |
| XL Catlin Seaview Survey | transect 36015 | 2015 | 28% | 2.56 km | doi:10.14264/uql.2019.930 |
| XL Catlin Seaview Survey | transect 36014 | 2015 | 34% | 3.96 km | doi:10.14264/uql.2019.930 |
| XL Catlin Seaview Survey | transect 36017 | 2015 | 22% | 4.25 km | doi:10.14264/uql.2019.930 |
| XL Catlin Seaview Survey | transect 36016 | 2015 | 19% | 4.83 km | doi:10.14264/uql.2019.930 |
| Spalding et al. (2025) | Salomon - Boddam Lagoon (N, 1-4 m) | pre-bleaching baseline | 65% | 3.58 km | — |
Data & links
- Download benthic survey data (CSV) ↗
- Download all LOF-GRE data (933 sites) ↗
- CoralNet image repository for this region ↗
- Photo portfolio ↗
- Coral Reef Diagnostics page for this area ↗
All images from Coral Reef Diagnostics. Data are from the Khaled bin Sultan Living Oceans Foundation Global Reef Expedition, Coral Reef Diagnostics, and the organizations named in the data sources above.
© Coral Reef Diagnostics.
References
- Mayfield AB, Dempsey AC (2026). Using tourist diver images to estimate coral cover and bleaching prevalence in a remote Indian Ocean coral reef system. Oceans 7(1):1. PDF
- Sheppard C, Harris A, Sheppard A (2008). Archipelago-wide coral recovery patterns since 1998 in the Chagos Archipelago, central Indian Ocean. Marine Ecology Progress Series 362:109-117. PDF
- Lange ID, Benkwitt CE, McDevitt-Irwin JM, Tietjen KL, Taylor B, Chinkin M, et al. (2021). Wave exposure shapes reef community composition and recovery trajectories at a remote coral atoll. Coral Reefs 40:1819-1829. PDF
- Spalding M, Bourasseau M, et al. (2025). Coral bleaching and mortality in the Chagos Archipelago, 2024. British Indian Ocean Territory Administration report (gray literature). PDF
- Gonzalez-Rivero M, et al. (2019). Seaview Survey photo-quadrat and image classification dataset. The University of Queensland (UQ eSpace) data collection. DOI