Kenya - Outer Kisite (Kisite National Park)

Setting

Visibility is moderate and blue-green, hazier than at Coral Garden, with a persistent green cast over the deeper background in many wide frames. A big, high-relief structure: long coral ridges and buttresses running out and down, separated by sand- and rubble-floored channels, with a coral-dense crest that the wide frames show as near-continuous living cover for meters at a stretch. Several frames look straight down the flank of a ridge from the crest into open blue; others sit on the sand at the base looking up at a wall of coral.

General benthic features

Between the ridges are rubble aprons of broken branch fragments and coralline-crusted pavement, and a few genuinely bare sand patches. Four elements repeat across the set and between them account for most of what is in frame. Massive nodular Porites-type hillsides. Whole slope faces are covered by a single knobby, close-packed massive coral in brown-mauve, knob after rounded knob to the edge of frame with only small pale cerioid Goniastrea/Favites-type colonies wedged into the gaps. These near-monospecific hillsides are massive Porites-type coral, not plate coral. Shingled foliose plate terraces. Just as abundant and just as characteristic: whorled, crisped plates overlapping plate on plate for the whole frame, every surface sculpted with fine concentric ridges and edged in pale cream (e.g., Image 2).

2

Color runs dusty mauve-pink to brick-brown — pigmented, if muted. One superb rosette colony a meter or more across sits alone on rubble. The concentric-ridge sculpture is consistent with Pachyseris/Merulina- or Echinopora-type taxa but is not resolvable to genus at this range, so growth form is what is claimed here. Branching and corymbose Acropora thickets. The crest and upper slope carry dense corymbose, digitate, and staghorn Acropora (e.g., Image 1).

1

Meandroid brain corals. Scattered rather than dominant but conspicuous: a large cream-and-tan Platygyra-type dome resting on sand, a smaller salmon-pink meandroid colony ringed by bleached-white neighbors and soft coral, and a broad meandroid pavement into which a giant clam is set. Elsewhere, feathery red and pink Dendronephthya-type soft corals stand on the sand, red and orange encrusting sponges fill the interstitial rock, and a sea cucumber lies across a bleached Acropora bed.

Coral cover

• Reference: Mayfield (2025)
• Data file: (Mayfield, 2025-Supplemental File S1)
• CoralNet submission package (accession #4963)
• Coral cover 37% — and 66% of hard coral tissue bleached (March-April 2024).
• Measured from 85 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.

Stressors

One isolated dome on sand is a textbook of partial bleaching — the same knob texture throughout, but irregular chalk-white and pale-mint zones bleeding across a mauve-brown colony, with no tissue loss. Branching Acropora is the growth form the heat took: frame after frame shows beds of bone-white and pale-lavender branching colonies — skeletal architecture intact, branch tips sharp, no algal fouling, which reads as fresh bleaching rather than old mortality — interleaved with tan and olive colonies that held pigment. The single most telling frame sets a fully pigmented yellow-green corymbose dome directly against a bed of stark white branching Acropora, margin to margin. Bleaching is unmistakable and widespread in the set, and it is strongly growth-form structured. The branching and corymbose Acropora stands are the casualties — in several frames the majority of branching colonies in view are white. The massive Porites hillsides and the foliose plate terraces are, by contrast, largely pigmented, with bleaching on them showing as patches on otherwise colored colonies rather than whole-colony whitening; one bleached foliose plate colony and one bleached tabular plate do appear. Older mortality is present too: at least one large plate colony is entirely dead and carpeted in turf and sediment, and the rubble aprons are made of branch fragments. No crown-of-thorns seastar appears in any of the 87 frames, and no unambiguous disease lesion is visible. Typical recent thermal stress: mean annual maximum of 5.1 degree heating weeks (2021-2025, NOAA CRW; Tanzania virtual station, whose polygon covers the Kisite-Mpunguti area). Seawater here was an estimated 31.6°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's Kenya virtual station recorded a peak of 13.5 degree-heating weeks on 18 April 2024, a level not reached there before in records going back to 1985; the Tanzania virtual station that covers this reef peaked at 16.0 on 16 April 2024. 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 headline is a genuinely enormous school of bluestripe snapper (Lutjanus kasmira) — packed edge to edge in places and standing off the reef as a solid yellow wall in others. Two further schools of deep-red crescent-tail bigeye-type fish hang over the slope, and single soldierfish and red squirrelfish sit in the reef matrix. Also present: yellow-and-blue fusiliers, damselfish, and anthias over the coral, a large octopus tucked into a rubble den beside a red sponge (photographed four times, from four angles), a big giant clam (Tridacna) with a purple-brown mantle beaded in pearly white, set into a brain coral pavement, and a hawksbill turtle resting on a rubble floor beneath a drape of ruffled cream-olive leather soft corals (Sarcophyton/Lobophytum-type) — a distinctly soft-coral-dominated overhang, quite unlike the hard coral ridges above it (e.g., Image 3, Image 4).

34

Comparisons with other data

REEFolution Foundation surveyed a station named Outer Kisite, 0.43 km away. Within 5 km, fifteen independent stations recorded hard coral cover between 1998 and 2020: seven by benthic survey, station-year means of 0.0–53%, and eight by MERMAID bleaching-protocol quadrats, station-year means of 21–56%; the nearest, WCS Kenya via MERMAID (quadrats) at Kisite corner, 0.30 km away, read 50% in 2016.

Dive record

Dived 21 Mar 2024 on the outer side of Kisite Marine National Park, during the 2024 Western Indian Ocean mass bleaching event; in-water temperature 31.6°C. Surveys were run with REEFolution.