Coral Reef Diagnostics

Egypt Red Sea - Nakari House Reef-South (Marsa Nakari)

Reef Check Foundation
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Part of the regional summaries: Egypt and Red Sea

05
Coral Reef Diagnostics
Coral Health Index: 2.00/5
Photo: Anderson Mayfield/Coral Reef Diagnostics
Country
Egypt
Survey date(s)
2024-09-20
Coordinates
24.9267, 34.9639
Coral cover
25%
Manual point count (102 photos) · other methods below
Observations
bleaching
Heat stress
Today’s heat load
30.6°C13.2°C-weeks
16 Sep 2026 · Alert Level 2
5-year thermal stress load
5-year mean max. degree heating weeks (DHW)
15.6°C-weeksi
2021–2025
NOAA Coral Reef Watch — Egypt 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 infoEgypt (NOAA CRW virtual station) · Northern and Central Red Sea ecoregion mean=12.2°C-heating weeks
Photographs
4
Site summary
Read this summary in:

Nakari House Reef-South, the first stop of the September 2024 Egypt survey leg, captured a graded sequence on a single dive - Anderson's own captions run from 'live corals' and 'survivors' through 'dying Acropora' to 'dead Seriatopora hystrix' and 'dead corals,' documenting bleaching mid-collapse on one reef in one day. Published cover was 25% with 50.4% of coral tissue bleached; a nearby Reef Check station at essentially the same spot has averaged 36.0% hard coral across seven surveys since 2010.

Water temp. during survey
30.5°Cii
+3.8°C vs the 2024 mean sea temperature (26.7°C)
ii Note: NOAA's regional station series averages 1.6°C warmer than the satellite pixel nearest this site (1.1 km away), which is used here instead.

Nine 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 within 5 km shown in orange — click a marker to open its page.

Photo credit & attribution

Site description

Setting

The southern arm of the Marsa Nakari house reef, and the first dive of the September 2024 Egypt leg with Red Sea Diving Safari.

General benthic features

The reef runs down from a shallow flat over a broad sand-and-pavement apron (e.g., Image 2).

2Image 2

Structure is low: knobby and encrusting Porites, olive and yellow-green Goniastrea/Favites heads, corymbose and staghorn Acropora stands, fine-branched Seriatopora hystrix, Pocillopora, and a good deal of open sand between them (e.g., Image 1, Image 3, Image 4).

1Image 13Image 34Image 4

Coral cover

Coral cover is 25.1% ± 16.9 across 102 photographs, 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.

Stressors

The site record reports 50.4% of coral tissue bleached at about 21.9°C-weeks DHW, and adds a standing note for the Egypt leg: nearly all corals at these sites showed some degree of bleaching. What makes this dive worth reading closely is not the reef but the sequence Anderson photographed on it. He captioned frames "live corals", "survivors", "resilient Acropora sp.", "dying Acropora sp.", "dying Pocillopora", "dying Porites", "mostly dead Acropora", "dead Acropora", "dead Seriatopora hystrix", and "dead corals" — a graded series from healthy through dying to dead, on one reef on one day.

Comparisons with other data

The site record also carries an external cross-reference: Reef Check's Marsa Nakari South station sits 0.10 km away and reports a mean of 36.0% hard coral over seven surveys (2010–2025). The two are reported side by side and deliberately not averaged — different methods (CRD photographic point count vs Reef Check point-intercept transect), and at 0.10 km they are almost certainly the same reef. Different station, different observers: a near-concurrent cross-check, not a repeat of this site.

Other notes

See flags.

CV model comparison

Computer vision on this site's own photographs gives In-house DINOv3 point classifier 42% — 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, 102 photos); the other rows are AREA-level (Marsa Nakari) 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 674–1,180 frames, the CV arms ran on the 30- and 129-frame hand-scored reference subsets. CoralNet is n/a by design: the reference set IS the hand-scored set. DINOv3 is restricted to frames it never saw. 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)25.1
In-house DINOv341.8
Claude27.7
Reef Check 2024 (same site)43.1

Independent surveys nearby

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.
0%17%34%51%68%200320142025Reef Check 2003: 39%Reef Check 2003: 49%Reef Check 2005: 23%Reef Check 2005: 43%Reef Check 2005: 61%Reef Check 2006: 9.4%Reef Check 2007: 22%Reef Check 2007: 39%Reef Check 2010: 35%Reef Check 2010: 37%Reef Check 2011: 39%Reef Check 2011: 46%Reef Check 2012: 53%Reef Check 2013: 30%Reef Check 2013: 31%Reef Check 2013: 43%Reef Check 2014: 52%Reef Check 2015: 40%Reef Check 2015: 41%Reef Check 2017: 53%Reef Check 2018: 37%Reef Check 2018: 40%Reef Check 2019: 59%Reef Check 2022: 53%Reef Check 2024: 40%Reef Check 2024: 47%Reef Check 2024: 51%Reef Check 2024: 58%Reef Check 2025: 27%Reef Check 2025: 29%Dr. Coral (CRD) 2024: 25%Year-averaged across all programs: no detectable trend (+0.54 pp per year, not separable from zero; 16 years)
Reef Check Dr. Coral (CRD)Year-average (no detectable trend)

Within 5 km, 9 independent survey stations recorded hard coral cover in 50 surveys between 2003 and 2025. Of the 8 stations surveyed in more than one year, 5 declined, 1 increased, and 2 changed by less than 5 percentage points between their first and latest surveys. The longest record, Marsa Nakari South (Reef Check, 0.10 km away), went from 37% in 2010 to 29% in 2025. Surveys since 2021 average 43% (range 27–58%, n=7). This site's own estimate (25%) is indistinguishable from the recent range (27–58%): the 1.8-point gap is inside the ±7 percentage-point noise between methods; the methods differ, so the comparison is context, not a like-for-like test.

Collected by other programs using different methods (Reef Check uses point-intercept transects), 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
Reef CheckSamaka Mogeha (North Marsa Nakari)2003–200543–49% (3 surveys)1.18 km—
Reef CheckCheckpoint2003–201322–43% (3 surveys)3.63 km—
Reef CheckMarsa Tondoba/3 Sisters2005–201239–61% (3 surveys)2.29 km—
Reef CheckGotta Nakari2005–20069.4–23% (3 surveys)2.70 km—
Reef CheckMarsa Nakari South2010–202529–40% (14 surveys)0.10 km—
Reef CheckMarsa Nakari North2010–202527–47% (13 surveys)0.22 km—
Reef CheckMarsa Um Tondoba- 3 Sisters201452%4.61 km—
Reef CheckShaab Nakari, north-east side2017–202451–59% (6 surveys)2.88 km—
Reef CheckDream Lagoon Marsa Alam2022–202453–58% (4 surveys)1.55 km—

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.