Saudi Red Sea - Alrass Alakhdar (Yanbu)
Part of the regional summaries: Saudi Arabia - Yanbu, Saudi Arabia, and Red Sea
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Al Madinah and Makkah (NOAA CRW virtual station)Alrass Alakhdar had a published coral cover of 30% and a bleaching figure of 59% of coral tissue in the 2023 Yanbu survey leg — a densely built reef flat of knobby Porites, Acropora, and vividly colored pocilloporids that was, on the day it was photographed, more than half bleached.
سجّل الراس الأخضر تغطية مرجانية منشورة بلغت 30% ورقم ابيضاض بلغ 59% من نسيج المرجان في جولة مسح ينبع في 2023 — مسطح شعابي كثيف البناء من Porites العُقدية وAcropora وبوسيلوبوريات زاهية الألوان، كان في يوم تصويره مبيضًّا بأكثر من النصف.
ترجمة هذا الملخص بالذكاء الاصطناعي؛ النص الإنجليزي هو المعتمد.
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Anderson's dive computer's DiverLog reading was 28.0°C (a single stored value, probably a dive mean). Note: NOAA's regional station series averages 2.7°C warmer than the satellite pixel nearest this site (2.7 km away), which is used here instead.One independent survey station shown with the program’s logo — click one to see how far it is from this site.
4 of the 48 photographs on this page are shown beside the text that discusses them under "Site description" below.
Site description
General benthic features
The reef is a shallow-to-mid fringing structure that runs from a wave-lit reef flat a meter or two under the surface down a face onto deeper bommies and pinnacles. The flat is a tightly packed mosaic of knobby and columnar Porites, corymbose and digitate Acropora, and pocilloporids in the vivid magenta, hot-pink, and lilac color forms the northern Red Sea is known for, over a base of coralline-crusted rock (e.g., Image 1, Image 2, Image 3).
From the surface, the same Porites-and-Acropora framework can be seen continuing onto isolated pinnacle tops in blue water, with butterflyfish, sergeant majors, and anthias working around them.
Coral cover
- Reference: Mayfield (2025)
- Data file: (Mayfield, 2025-appendix A)
- CoralNet submission package (accession #5546)
- 30% ± 15% SD across 59 photographs. All of its photographs were taken on snorkel in under 5 m after the dive (the dive log: the camera locked up early in the 28 m dive), so the value describes the reef top only.
Stressors
Its published bleaching figure was 59% of coral tissue at roughly 14.9°C-weeks DHW on the survey date (16 September 2023; NOAA Coral Reef Watch, Madinah-Makkah (Saudi Arabia) virtual station). Those two numbers belong together — this was a densely coral-covered reef that was, on the day it was photographed, more than half bleached. The bleaching is the story of this dive (e.g., Image 4).
Comparisons with other data
Apart from our own published survey shown here, we found no other surveys at this site as of 2026. Within 5 km, one independent station, Aeby et al. (2021) at Yanbu 6, 4.25 km away, read 51% in 2015.
Dive record
One morning dive to 28 m on 16 September 2023 with Umluj Dive Center, on the second day of the Yanbu leg.
CV model comparison
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The reference is this dive site's own published CoralNet point count by the author (Mayfield 2025, Environments 12:248, Appendix A; most frames annotated by CoralNet's AI, trained and checked by the author). The computer-vision rows are this site's own values: Claude is a blind point count of all of the site's edited photographs, and CoralSCOP is the site's finished survey of its edited photographs. They are on different frame sets from the published count, a row under 30 frames is indicative only, and no computer-vision method yet estimates coral cover accurately on new images.| Method | Hard coral cover (%) | Photos (n) ± SE |
|---|---|---|
| Published point count (CoralNet-assisted) | 29.6 | |
| CoralSCOP edited | 36.0 | n = 58 |
| Claude (edited photos) | 39.2 | n = 57 · SE 1.9 |
The two computer-vision methods agree within 3.2 pp (36.0–39.2%) and read 6.4–9.6 pp above the published point count (29.6%); the headline is the published point count because it is the site's published value (CoralNet-assisted: most frames were annotated by CoralNet's AI, trained and checked by the author).
See a more detailed, stand-alone version of this table.
Independent surveys nearby
Within 5 km, 1 independent survey station 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 estimate (30%) is not compared with these surveys: none lies within 2 km.
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 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 |
|---|---|---|---|---|---|
| Aeby et al. (2021) | Yanbu 6 | 2015 | 51% | 4.25 km | doi:10.1371/journal.pone.0246854 |
Data & links
All images from Coral Reef Diagnostics. Data are from Coral Reef Diagnostics and the organizations named in the data sources above.
© Coral Reef Diagnostics.
References
- Mayfield AB (2025). Using Tourist Diver Photos to Assess the Effects of Marine Heatwaves on Central Red Sea Coral Reefs. Environments 12:248. PDF
- 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