Kenya - Round Reef (Watamu) snorkel

General benthic features

The reef's structure is variable, and the quadrats sort it out. Frame codes such as RRQ1-2 cite photographs on file; the gallery shows a selection of them, and the rest are photos not shown. RRQ1, RRQ2, and RRQ3 are the high-relief end: coalesced massive-and-encrusting bommies with overlapping plate-like margins under blue-green water (RRQ1-2, RRQ1-3, RRQ1-6, RRQ2-4) (e.g., Image 1).

1

RRQ3 is the best piece of reef in the set — a bommie face carpeted almost continuously in orange-tan pigmented knobby and encrusting colonies (RRQ3-4, RRQ3-5, RRQ3-10), with yellow-cream foliose plates and magenta crustose coralline in close-up (RRQ3-6) (e.g., Image 2).

2

At the other end, RRQ15 is close to barren: dense algal turf and pink coralline pavement with no live coral resolvable inside the frame in RRQ15-1, RRQ15-3, or RRQ15-4. RRQ4 and RRQ6 are the turbid, low-visibility stretches — green water over algae-covered boulders and pink coralline pavement carrying only scattered nubbins (RRQ4-1, RRQ4-2, RRQ6-1, RRQ6-2). The heavy algal canopy is real and is concentrated in RRQ12, RRQ15, and RRQ16: tall brown Sargassum-like fronds standing over the reef in RRQ12-6, RRQ12-7, RRQ12-9, and RRQ12-10, and thick dark-red foliose macroalgae fields in RRQ10-2, RRQ10-5, RRQ11-3, and RRQ7-1. The framework is built around massive Porites-type mounds and meandroid brain corals, with cerioid Goniastrea/Favites-type colonies, foliose plating colonies, corymbose and digitate Acropora, and cauliflower Pocillopora filling in around them. RRQ9 is the massive-coral quadrat: a meter-scale meandroid brain standing clear of the pavement (RRQ9-12), a stark white dome perched on rock (RRQ9-16), three large pale domes together in blue water (RRQ9-19), and a fully pigmented olive-gold cerioid massive (RRQ9-8). RRQ6 is dominated by one large meandroid brain photographed from four angles (RRQ6-3, RRQ6-4, RRQ6-5, RRQ6-7). Pocillopora is confirmed in the close-ups RRQ14-8 and RRQ14-9, bone-white and sitting directly against a still-green pigmented cerioid colony. Other benthos and fauna: dead framework crusted pink and magenta with coralline algae underlies most of the shallow quadrats (RRQ4-6, RRQ7-8, RRQ8-11, RRQ15-2, RRQ15-4); cream-yellow foliose plating colonies form a distinct group in RRQ7-2, RRQ7-3, RRQ7-4, RRQ8-9, and RRQ3-6; green fleshy and turf algae carpet the shallowest frames (RRQ1-9, RRQ13-9, RRQ9-17).

Coral cover

• Reference: Mayfield (2025)
• Data file: (Mayfield, 2025-Supplemental File S1)
• CoralNet submission package (accession #4963)
• Read quadrat by quadrat, the site is far more heterogeneous than a single number suggests, and the low published cover is earned in specific places rather than spread evenly.
• Coral cover 18% — and 70% of hard coral tissue bleached (March-April 2024).
• Measured from 175 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.
• Cover was 18% and bleaching 70%.

Stressors

On bleaching, the full set changes the emphasis. Branching corals do carry a large share of it — white corymbose Acropora recur in RRQ1-7, RRQ10-4, RRQ10-16, RRQ12-3, RRQ12-8, RRQ2-3, RRQ3-8, and RRQ7-9 — but they are not where the bleaching is worst (e.g., Image 4).

4

The most completely white colonies at Round Reef are the massives and the brains: a bright white meandroid brain in RRQ1-8, a large white brain beside a still-pigmented cerioid neighbor in RRQ12-2, white massive and lobate Porites in RRQ10-14, RRQ10-17, RRQ2-12, RRQ2-14, RRQ2-15, RRQ12-13, RRQ8-12, RRQ8-13, RRQ9-2, RRQ9-3, RRQ9-9, and RRQ9-16, white encrusting Porites sheets in RRQ6-9 and RRQ8-5, and bleached brains and a bleached cerioid Favites-type colony in RRQ4-5 and RRQ4-7. Partial-colony bleaching is visible too: RRQ9-18 is a brown massive Porites carrying one large irregular white patch, and RRQ10-19 pairs a fully white brain with a partly pigmented corymbose Acropora below it. The genuinely striking thing in this set is how much pigment survived, and how it sits colony by colony rather than by taxon. Fully pigmented gold, tan, and orange-brown corymbose Acropora recur across at least seven quadrats — RRQ10-12, RRQ10-13, RRQ11-9, RRQ11-10, RRQ12-11, RRQ13-5, RRQ14-1, RRQ14-2, RRQ14-12, RRQ16-1, RRQ16-3, RRQ16-8, RRQ9-10, and RRQ9-17 (e.g., Image 3) — and an orange-brown branching colony in RRQ16-6 looks fully healthy, standing in the middle of purple-red macroalgae.

3

Healthy and bleached colonies side by side are not a one-off: RRQ11-9 and RRQ11-10 each hold a fully pigmented brown corymbose Acropora and a bone-white one of the same growth form on the same patch of pavement, RRQ10-12 and RRQ10-13 show a pigmented orange colony below a white one on the ridge above, and RRQ14-1 and RRQ14-2 catch a gold Acropora and a white one inside the same quadrat frame. Several Acropora sit between the two states, cream with distinct lavender-violet branch tips (RRQ9-4, RRQ9-7, RRQ3-2, RRQ3-3, RRQ3-9) — the pale-violet cast is consistent across frames and growth forms, though these are color-adjusted exports and the exact hue should not be pressed. Across 178 of the 181 frames on file there are no crown-of-thorns seastars, no identifiable disease lesions, no predation scars, and no fishing gear or debris. Typical recent thermal stress at the Kenya virtual station is a mean annual maximum of 4.9 degree heating weeks (2021-2025, NOAA CRW), so 2024 stood far above that typical level. 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

The frames are benthos-focused, but they are not empty of fish: a powder-blue surgeonfish sits beside two pale domes in RRQ2-13, a blue surgeonfish crosses a gold plating colony in RRQ10-20, and small damselfish and chromis appear in RRQ2-4, RRQ9-14, RRQ9-15, RRQ10-17, RRQ11-6, and RRQ16-5. No aggregations, no large macrofauna.

Comparisons with other data

We found no other surveys at this site as of 2026. Within 5 km, five 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 five 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, 0.36 km away, read 8.8% in 2022.

Dive record

Surveyed 27 Mar 2024 at Round Reef, Watamu, at 32.5°C, in the middle of the 2024 Western Indian Ocean mass bleaching event, with A Rocha. The 178 reviewed frames (of 181 on file) record a quadrat survey, not a swim-through: fifteen PVC frames and meter bars (RRQ1-RRQ4, RRQ6-RRQ16) laid out over reef flat and bommie tops, with the survey team visible in the water in RRQ6-8 and hands with dive slates in RRQ10-3, RRQ16-3, RRQ16-7, RRQ2-5, RRQ3-2, and RRQ8-10. Surveys were run with A Rocha.