Kenya - Sandy Patch/Point (Mombasa)

Setting

Water is Mombasa-typical — green and plankton- and sediment-laden in the shallower, more sheltered frames, and noticeably bluer and clearer over the deeper bommies, where fusiliers stand out against open blue water. The site is not uniformly thin pavement.

General benthic features

Roughly half the wide frames do show low-relief fringing pavement — turf- and crustose-coralline-covered rock with sand pockets and scattered colonies, in places heavily algal with only a handful of corals in frame (e.g., Image 1).

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The other half show near-continuous coral: overlapping foliose and laminar plate fields several meters across, large massive domes, and corymbose branching thickets, with a few steeper bommie faces that a diver can swim over. Cover is patchy at the scale of a single swim. Laminar and foliose plate corals dominate — Turbinaria, Montipora, and Echinopora type plates, plus ridged Merulina/Pachyseris type colonies, many a meter or more across and edged with clean white growing margins. Massives are the second element: cerioid Favites/Goniastrea type colonies, meandroid Platygyra and Symphyllia/Lobophyllia type domes (several in striking violet and lilac), and large Astreopora and Porites boulders. Branching coral is present but subordinate — corymbose Pocillopora and Acropora, and one bright yellow-green branching Porites stand. Soft corals are conspicuous throughout: ruffled Sarcophyton toadstools, digitate Lobophytum and Sinularia, pale lilac Xenia/Anthelia mats, and red, orange, and white Dendronephthya-type colonies on the deeper faces (e.g., Image 2).

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Orange, yellow, and red sponges and pink encrusting coralline are everywhere on the interstitial rock.

Coral cover

• Reference: Mayfield (2025)
• Data file: (Mayfield, 2025-Supplemental File S1)
• CoralNet submission package (accession #4963)
• Coral cover 29% — and 45% of hard coral tissue bleached (March-April 2024).
• Measured from 117 white-balanced photographs taken at this site during the 2024 Western Indian Ocean mass bleaching event and point-annotated in CoralNet, published in Mayfield, A.B. (2025) A Citizen Science Approach for Documenting Mass Coral Bleaching in the Western Indian Ocean. Environments 12(8):276. doi:10.3390/environments12080276.
• This is a published diver-photograph point-annotation value, not a computer vision estimate, and it is not recomputed here.
• Across the 20 Kenyan sites the mean was 30% coral cover and 77% of tissue bleached.

Stressors

Bleaching is visible across the set but partial and mosaic. The single clearest frame sets a fully pigmented dark chocolate-brown cerioid massive hard against a large pale lilac-blue meandroid colony along a shared margin. Other frames show a massive Porites that is cream-to-mint with one retained salmon pigment patch and several corymbose Pocillopora and Acropora colonies that are stark white or pale cream; a pale ruffled leather soft coral roughly a meter across is no paler than the smaller leather soft coral beside it, so no bleaching is claimed for it. Bleaching here was not sharply growth-form dependent: the laminar plates were not hit hardest while massive and meandroid colonies held pigment. Many laminar and foliose plates are deeply pigmented dark brown, maroon, and olive, and some of the palest colonies in the whole set are meandroid and cerioid massives. The pattern reads colony-by-colony rather than growth-form-by-growth-form. No crown-of-thorns seastars appear in any frame. A few plate colonies carry white patches that could be recent partial mortality or simply active growing margin; the photographs do not resolve which, and no unambiguous disease lesion is visible. Typical recent thermal stress: mean annual maximum of 4.9 degree heating weeks (2021-2025, NOAA CRW; Kenya virtual station). Seawater here was an estimated 32.5°C during the survey (read from the TG7 underwater camera and not validated, per Mayfield 2025, Environments 12:276, Table 1; the Kenya survey-wide mean of 32.0°C matched the 1998 event), and NOAA recorded a peak of 13.5 degree-heating weeks on 18 April 2024, the highest for Kenya since records began in 1985. For the 2024 Kenya survey as a whole, Mayfield (2025, Environments 12:276) estimated that in situ temperatures ran about 1.3°C above NOAA's, so that "nearly 22 DHWs may actually have transpired"; those in situ readings came from the TG7 underwater camera and have not been validated.

Fish and other fauna

A green turtle resting on the reef. A crocodilefish, superbly camouflaged on rubble, and a banded spiny lobster under a ledge were both seen here. A large trevally and a school of big dark-bodied fish out in the blue; schools of yellow-striped fusiliers and yellowfin snapper; sweetlips, parrotfish, angelfish, a butterflyfish, sergeant majors, and blue chromis; a shoal of silversides over a bommie. Two large tan anemones with fully expanded tentacles, a blue Linckia-type seastar, a Diadema urchin, and a spotted sea cucumber. The dive also produced an unusually good run of phyllidiid nudibranchs, photographed repeatedly on Sinularia: the black-ridged, yellow-tuberculate Phyllidia varicosa type and the white-pustuled Phyllidiella pustulosa type (e.g., Image 4).

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Comparisons with other data

We found no other surveys at this site as of 2026. Within 5 km, 22 independent stations recorded hard coral cover between 2003 and 2024: two by benthic survey, station-year means of 22–29%, and 21 by MERMAID bleaching-protocol quadrats, station-year means of 9.7–54% (one station appears in both); the nearest, WCS Kenya via MERMAID (quadrats) at Taa, 0.43 km away, read 14% in 2009.

Dive record

Surveyed 11 Mar 2024 with Mombasa Marine Park, during the 2024 Western Indian Ocean mass bleaching event. Surveys were run with Mombasa Marine Park.