Egypt Red Sea - Om Halhala (Marsa Nakari)
Part of the regional summaries: Egypt and Red Sea
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Egypt (NOAA CRW virtual station)Om Halhala is a dense coral slope built mainly on broad fields of massive Porites — and a large share of that framework was found bleached chalk-white at field scale, dozens of colonies across in a single frame, while nearby Acropora thickets held full color. Published cover was 24% with 61% of coral tissue bleached.
أم حلحلة منحدر مرجاني كثيف مبني أساسًا على حقول واسعة من Porites الكتلية - وقد وُجد جزء كبير من هذا الهيكل مبيضًّا بلون أبيض طباشيري على نطاق الحقل، عشرات المستعمرات في إطار واحد، بينما حافظت أجمات Acropora القريبة على كامل ألوانها. وبلغت التغطية المنشورة 24% مع ابيضاض 61% من نسيج المرجان.
ترجمة هذا الملخص بالذكاء الاصطناعي؛ النص الإنجليزي هو المعتمد.
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Note: NOAA's regional station series averages 1.5°C warmer than the satellite pixel nearest this site (1.7 km away), which is used here instead.4 of the 20 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 well-built coral slope, dense and structurally complex, dropping from shallow water down onto a white sand plain with scattered outlying bommies (e.g., Image 1).
Its dominant element is massive coral: broad fields of lobate and knobby Porites that form the framework, with corymbose and staghorn Acropora, pocilloporids, and encrusting plates layered over and between them (e.g., Image 3).
Large columnar bommies rise several meters off the slope (e.g., Image 2).
Coral cover
- Reference: Mayfield (2025)
- Data file: (Mayfield, 2025-appendix A)
- CoralNet submission package (accession #5546)
- 24% ± 15% SD across 216 photographs.
Stressors
The site record reports 61% of coral tissue bleached at about 25.7°C-weeks DHW on the survey date (21 September 2024; NOAA Coral Reef Watch, Egypt virtual station). A very large proportion of the Porites framework is white (e.g., Image 4).
One frame shows a continuous field of lobate Porites, dozens of colonies across, in which effectively every colony is chalk-white, running from the foreground to a bleached bommie in the background — with dark pigmented Acropora thickets holding normal color on the opposite side of the same frame.
Comparisons with other data
Apart from our own published survey shown here, we found no other surveys at this site as of 2026. If you would like to share yours, please email us.
Dive record
The second dive of 21 September 2024 with Red Sea Diving Safari.
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) | 24.0 | |
| CoralSCOP unedited | 30.3 | n = 221 |
| CoralSCOP edited | 30.2 | n = 200 |
| Claude (edited photos) | 29.1 | n = 206 · SE 1.2 |
The three computer-vision methods agree within 1.2 pp (29.1–30.3%) and read within 6.3 pp of the published point count (24.0%).
See a more detailed, stand-alone version of this table.
Data & links
All images from Coral Reef Diagnostics. Data are from Coral Reef Diagnostics and NOAA Coral Reef Watch.
© Coral Reef Diagnostics.