Saudi Red Sea - Cave Reef (Thuwal)

Setting

The site is named for its caverns, and one frame is shot from inside one — looking up through a ragged gap in the reef roof at bright surface light, the walls in silhouette. Outside the caves the structure is a field of eroded limestone pinnacles and buttresses rising from white sand, tall, undercut, and heavily bioeroded, standing in hazy blue water (e.g., Image 1, Image 2).

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General benthic features

Coral is patchy and mostly small. The living component is dominated by massive and encrusting forms rather than branching ones: red-brown meandroid Lobophyllia/Symphyllia-type colonies sitting free on sand, olive and khaki Goniastrea, Favites, and Astreopora domes on pinnacle shoulders, purple and lavender pocilloporids, encrusting Montipora-type sheets, and giant clams (Tridacna) with electric-blue and green mantles set into the pavement (e.g., Image 3).

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Between them, a great deal of the surface is old, algal-filmed, coralline-crusted dead framework (e.g., Image 4).

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Coral cover

Coral cover is 16.5% ± 19.7 across 68 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. The standard deviation of 20 is larger than the mean itself, which is the honest signature of a site where individual frames swing between bare pavement and dense colony clusters. The site record's prose gives the 9 February visit as 16% cover with 26.8% of coral tissue bleached, with no accumulated heat stress at the time.

Stressors

Grazing pressure is visible: Anderson captioned one frame "fish bites" for the scatter of small fresh white parrotfish scars across the faviid colonies in it.

Comparisons with other data

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

Dive record

A single winter dive to 27.2 m on 9 February 2024 at 24°C, the second dive of a day that started at Rose Reef, worked with Coastline (KAUST).