Coral Reef Diagnostics

Saudi Red Sea - Rose Reef (Thuwal)

⬇ Download this page as a report card

Part of the regional summaries: Saudi Arabia - Jeddah / KAUST (Thuwal) / Rabigh, Saudi Arabia, and Red Sea

05
Coral Health Index: TBD
Photo: Anderson Mayfield/Coral Reef Diagnostics
Country
Saudi Arabia
Survey date(s)
2023-09-08
2023-11-11
2023-11-17
2024-02-09
2024-09-28
2024-10-04
Coordinates
22.3106, 38.8867
Coral cover
15%
Manual point count (720 photos) · other methods below
Observations
bleaching
Heat stress
Today’s heat load
33.4°C3.6°C-weeks
16 Sep 2026 · Bleaching Warning
5-year thermal stress load
5-year mean max. degree heating weeks (DHW)
14.3°C-weeksi
2021–2025
NOAA Coral Reef Watch — Makkah-Madine Saudi Arabia virtual station
i 5-year mean max. DHW is the mean of the annual maximum DHWs over the five complete years named above, not conditions today.
More infoMakkah-Madine Saudi Arabia (NOAA CRW virtual station) · Northern and Central Red Sea ecoregion mean=12.2°C-heating weeks
Photographs
11
Site summary
Read this summary in:

Rose Reef is the most heavily surveyed Thuwal site (720 photographs across six visits), a near-vertical wall dropping to 32-36 m with a fine mosaic of encrusting faviids, small pocilloporids, and foliose plates, plus black wire corals off the lip. Its shallow reef flat showed unambiguous mass bleaching in November 2023 - multiple tabulate and corymbose Acropora colonies glowing white alongside pigmented neighbors, and even host anemones bleaching white while their resident anemonefish stayed in place - and the paper's bleaching figures here range from 24.3% to 61.8% of coral tissue, the widest swing of any site in the set.

Max. depth dived
36.0 m
deepest of 5 logged dives

Two independent survey stations shown with the program’s logo — click one to see how far it is from this site.

8 of these 11 photographs are shown beside the text that discusses them under "Site description" below.

1410

Photo credit & attribution

Site description

Setting

The site is a wall. Several dives ran to 32–36 m and the frames show why: a near-vertical limestone face plastered with small colonies from the surface down, dropping past a fish-swarmed mid-water zone onto a flat, low-relief rubble and sand floor (e.g., Image 2, Image 8).

2Image 28Image 8

General benthic features

A frame Anderson captioned "view from 35 m" is that floor — gray-blue, low, almost entirely coralline-crusted rubble with scattered small massives and nothing upright. The wall itself carries a fine-grained mosaic: encrusting and submassive faviids, small pocilloporids, tan, and orange encrusting Montipora-type sheets, foliose Turbinaria/Echinopora-type plates with clean white growing margins, delicate gray and lilac soft corals with extended polyps, sponges and crustose coralline in pinks and reds, and black wire corals (Cirrhipathes-type) springing off the lip into open water (e.g., Image 5, Image 7, Image 9, Image 11).

5Image 57Image 79Image 911Image 11

The shallows are a different reef — a wave-washed flat with tabulate and corymbose Acropora right under the surface, and it is there, in the November 2023 frames, that the bleaching in the published record is unmistakable in the photographs.

Coral cover

Coral cover is 14.5% ± 14.4, quoted verbatim from Mayfield, A.B. (2025) Environments 12:248 — Red Sea 2023-24 bleaching; CoralNet point annotation, Appendix A: a manual, diver-annotated CoralNet point count from Anderson's own published work, not a computer vision output and not recomputed here.

Fish and other fauna

Anthias hang in red clouds against it, and dense chromis and fusilier schools work the blue (e.g., Image 3, Image 6).

3Image 36Image 6

Comparisons with other data

No independent survey was made at this exact site; the nearest ones are listed in the table below.

Dive record

The most heavily worked of the Thuwal sites — six visits between September 2023 and October 2024 with Coastline (KAUST), and 720 annotated photographs, more than any other site in this Red Sea set.

Other notes

See flags.

Survey summary

Rose Reef: surveyed 6 times, Sep 2023–Oct 2024; bleaching ranged from 24.3% to 61.8% of coral tissue across visits (CoralNet point counts; Mayfield 2025, Environments 12:248). Surveyed in partnership with Coastline (KAUST).

CV model comparison

Computer vision on this site's own photographs gives ⚠ In-house DINOv3 point classifier 48% — reported alongside rather than merged, because as of September 2026 no computer-vision method estimates coral cover accurately on new images.
Headline is the reference value; every other row is listed beside it for comparison and none is averaged in.
More infoThe reference row is this dive site's own published value (Mayfield 2025, Appendix A, 720 photos); the other rows are AREA-level (Thuwal) comparisons, not run on this site's frames. ⚠ The comparison rows are REGIONS, not dive sites: the paper's main tables report cover by region, and this site's own value comes from its Appendix A. ⚠ The manual column and the CV columns are on DIFFERENT FRAME SETS. The published cover spans the region's full photo set (173–2,567 frames, most of them CoralNet robot-labeled); the CV arms ran only on the hand-scored reference subset, which is 6 frames at Thuwal, 274 at Jeddah and 173 at Rabigh. Read Thuwal's model columns as indicative only. CoralNet is n/a by design: the reference set IS the hand-scored set, so those frames carry no independent robot label to compare against. DINOv3 is restricted to frames it never saw, and reads roughly double the published cover at every Red Sea region. ⚠ 'unassigned region' is not a place: 135 frames carry no region label in the CoralNet metadata and map to no published row. It has no manual value and is excluded from the pooled reference. CoralNet automated point classifier: n/a — the reference set IS the hand-scored set; these frames carry no independent CoralNet robot label to compare against CoralSCOP (SAM-based mask-sum), unedited photos: pending — CoralSCOP run: 370/747 images scored at build time CoralSCOP (SAM-based mask-sum), edited photos: pending — CoralSCOP run: 370/747 images scored at build time
MethodHard-coral cover (%)
Manual (published)14.5
In-house DINOv347.5
Claude23.9

Dive history

DateTime inMax depth (m)Bottom time (min)
2023-09-0812:4515.050
2023-11-1110:4536.050
2023-11-1112:4035.050
2023-11-1710:3036.055
2024-02-0910:3932.441

Independent surveys nearby

Data availability near this site
Agency / programYear(s)Stations / distanceLink
Aeby et al. (2021)20151 station, 4.99 kmRecords ↓
Monroe et al. (2018)20151 station, 4.99 kmRecords ↓
Hard coral cover over time — this site and every independent station within 5 km. Programs are shown separately because they use different methods at different stations; the lines are not one comparable series. Coral Reef Diagnostics points are survey-year means of CoralNet point annotation from Mayfield (2025, Environments 12:248), Supplementary File S1 (2023: 8 September, 11 November, and 17 November, 364 photos; 2024: 9 February, 28 September, and 4 October, 356 photos). Their mean over all 720 photos is the pooled cover figure on this page.
0%10%20%30%40%201520192024Monroe et al. (2018) 2015: 28%Aeby et al. (2021) 2015: 39%Coral Reef Diagnostics survey 2023: 15%Coral Reef Diagnostics survey 2024: 14%Year-averaged across all programs: decreasing (-2.23 pp per year; 3 years)
Monroe et al. (2018) Aeby et al. (2021) Coral Reef Diagnostics surveyYear-average (decreasing)

Within 5 km, 2 independent survey stations recorded hard coral cover in 2015. The most recent nearby survey is from 2015, so these values predate recent heat stress. This site's own pooled estimate (15%) sits 13.3 points below the range of these surveys (28–39%); the methods differ, so the comparison is context, not a like-for-like test.

Collected by other programs using different methods, so these are context for the figures above, not a like-for-like comparison. Where a station was surveyed more than once the range is shown. Station names are not dive-site names.

Independent survey data near this site
AgencySite / locationDateHard coral cover (%)DistanceLink
Monroe et al. (2018)Offshore reef 1201528%4.99 kmHeatCRD database
Aeby et al. (2021)Shi'b Nazar201539%4.99 kmHeatCRD database

Data & links

All images from Coral Reef Diagnostics. Data are from Coral Reef Diagnostics and the organizations named in the data-sources table above.

© Coral Reef Diagnostics.

References

  1. Monroe AA, Ziegler M, Roik A, Röthig T, Hardenstine RS, Emms MA, et al. (2018). In situ observations of coral bleaching in the central Saudi Arabian Red Sea during the 2015/2016 global coral bleaching event. PLOS ONE 13:e0195814. PDF
  2. Aeby GS, Shore A, Jensen T, Ziegler M, Work T, Voolstra CR (2021). A comparative baseline of coral disease in three regions along the Saudi Arabian coast of the central Red Sea. PLOS ONE 16:e0246854. PDF
  3. Mayfield AB (2025). Using Tourist Diver Photos to Assess the Effects of Marine Heatwaves on Central Red Sea Coral Reefs. Environments 12:248. PDF