Kenya - Trumpet Area (Watamu)

General benthic features

The site is a low-relief reef flat rather than a wall or spur-and-groove: a broad algal-and-turf pavement with rubble, shallow sand pockets, and a few small undercut ledges, over which coral sits as discrete colonies rather than continuous framework. Wide shots taken minutes apart along the track look consistent — there is no zone of dense, healthy coral anywhere in the set. Corymbose and digitate staghorn corals (Acropora) are the most numerous stony corals, occurring as scattered dinner-plate to arm-span colonies, and they carry the visible bleaching load: frame after frame shows them brilliant, uniform bone-white to the branch tips (e.g., Image 2).

2

Large meandroid massives with worm-track ridges (a Platygyra-type morphology, one over a meter across) are the most conspicuous single heads and sit in an intermediate state — pale lilac-white with residual host pigment — while other massives, including a cerioid Favites-type head and several small Goniastrea-type domes, are still solidly pigmented (e.g., Image 1).

1

Extensive continuous stands on the pavement are not stony corals at all but lobed and ruffled leathery soft corals (Sarcophyton/Lobophytum-type), which carpet whole sections of flat in several frames; these too are affected, ranging from healthy chocolate-brown through washed-out cream to a colony Anderson recorded as bleached soft coral (e.g., Image 3).

3

Genuine foliose and plate stony corals are present but subordinate: tiered whorls, flat gray plates, and a large ridged Pachyseris-type sheet, most of them paled to cream. Between the corals the pavement is heavily algal: dense turf, maroon and crimson fleshy macroalgae, bright green segmented Halimeda (which Anderson noted as overabundant), and pink crustose coralline crusts on rubble, with orange encrusting sponges scattered through.

Coral cover

• Reference: Mayfield (2025)
• Data file: (Mayfield, 2025-Supplemental File S1)
• CoralNet submission package (accession #4963)
• Coral cover 21% — and 86% of hard coral tissue bleached (March-April 2024). Measured from 193 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.

Stressors

A handful of tabular and corymbose Acropora remain fully brown or golden-tan, and several colonies are caught mid-transition with white tips over a pigmented base, so the response is colony-specific as well as growth-form-specific. Submassive and encrusting Porites-type mounds appear both fully pigmented and stark chalk-white within the same frame. Partial mortality is already visible on the biggest colonies — bare skeleton furred with turf or bound by algal film across the top of encrusting sheets and one massive head. Typical recent thermal stress at the Kenya virtual station is a mean annual maximum of 4.9 degree-heating weeks (2021-2025, NOAA Coral Reef Watch); in 2024 NOAA recorded a Kenyan peak of 13.5 DHW on 18 April, a value not reached before in its record, which 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). No crown-of-thorns starfish (COTS) or other corallivores were evident.

Fish and other fauna

Between about 11:29 and 11:30 a dense aggregation of trumpetfish/cornetfish hangs in mid-water and drifts over the flat. Turtles were seen on at least two separate encounters (11:15-11:19), one resting among leathery soft corals and one grazing the algal pavement. A peacock mantis shrimp (Odontodactylus scyllarus) was shot at close range in coralline-crusted rubble (e.g., Image 4), and a small reticulate yellow-and-dark dorid nudibranch gets three macro frames at 11:40.

4

Also present: a blue sea star, a pale lobed fungiid, Moorish idols, bannerfish, powder-blue surgeonfish, a bluestripe snapper, and damselfish and chromis holding position over the coral heads in nearly every wide shot.

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, four independent stations (WCS Kenya / WCS Tanzania via MERMAID and WCS Kenya via MERMAID) recorded hard coral cover between 2008 and 2024: one by benthic survey, 28%, and four by MERMAID bleaching-protocol quadrats, station-year means of 8.8–25% (one station appears in both); the nearest, WCS Kenya via MERMAID (quadrats) at Watamu, 2.47 km away, read 8.8% in 2022.

Dive record

Surveyed 29 March 2024, roughly 11:04 to 11:57 off Watamu, during the 2024 Western Indian Ocean mass bleaching event; the topside frame shows the dive boat Mrembo on a flat, sunlit sea. Surveys were run with Extra Divers.