### BIEG06 — Egmont
**Date:** 2015-03-11
**GPS:** 6.63941°S, 71.33949°E · **In-situ temperature:** 29.4°C
**Frames reviewed:** 33 of 33 (100% of the site folder, `BiEg06-finished`)
**Coral cover:** 43.5% (formal transect surveys) · **10.4%** of coral bleached (CoralNet analysis of informal survey images; Mayfield & Dempsey 2026, Oceans) — **the highest bleaching figure of the Egmont sites**
**Live hard coral cover across methods** (n=33 photos): transect 43.5% · CoralNet points 30.1% · Coralscapes 23.3%. Deviation vs transect -20.2 to -13.4 pp. **Mean of 3: 32.3% ± 10.3.** (SD here reflects systematic method bias, not precision — photo methods read low at high cover; see CHAGOS_MULTIMETHOD_README.md.)  
**Coral genera identified:** 6 scleractinian — *Acropora* (staghorn, corymbose, tabular and digitate), *Pocillopora*, *Porites* (massive domes), *Montipora* (encrusting), *Favites*/*Goniastrea*, *Astreopora*. Also a chromodorid nudibranch compatible with *Hypselodoris* or *Chromodoris*. Growth-form calls from photographs, given as "compatible with". The genus count is genuinely low here: this reef is an *Acropora* near-monoculture, and that is the finding, not a review shortfall.
**Representative photos:** P3110562.jpg, P3110542.jpg, P3110526.jpg, P3110532.jpg, P3110557.jpg

BIEG06 is an *Acropora*-dominated reef at 43.5% transect cover, and the full 33-frame pass shows a site that is simultaneously the most structurally impressive and the most obviously stressed of the Egmont series. The framework is enormous: P3110537, P3110538, P3110541, P3110545, P3110553 and P3110561 show staghorn (*A. muricata*-type) and corymbose *Acropora* running unbroken across the whole field of view, interrupted only by clean white sand channels. Almost nothing else is present — a few domal *Porites*, honeycomb-corallite faviids compatible with *Favites* or *Goniastrea* in the macro frames, encrusting *Montipora*, small *Pocillopora*. The six-genus count is the lowest of any high-cover site reviewed and reflects real monodominance rather than a thin review.

**The stress signal here is the site's most important content, and it takes three distinct forms.** First, **widespread paling**: P3110553 and P3110537 show entire *Acropora* plains in a washed-out grey-white rather than the golden brown of a healthy stand, and P3110560 shows the same over a broad area beneath an emperor school. Second, **partial-colony bleaching on individual colonies**: P3110562 is a clean macro of a *Pocillopora* with numerous bone-white branch tips against pigmented bases, P3110515 shows a branching *Acropora* with extensively whitened tips, and P3110514 records a small cream-white colony that appears wholly bleached. Third — and most striking — **standing dead framework**: **P3110542** shows a large expanse of intact branching coral skeleton, grey-brown and algal-fuzzed with no live tissue, still standing in growth position among live colonies, and P3110489 shows piles of dead branch rubble across open pavement. Set against this, three frames (P3110506, P3110527, P3110543) document the opposite process — small pale *Acropora* recruits settled directly on dead, CCA-crusted substrate, including one growing on top of an algal-covered dead mass. A single dive therefore captures mortality and recruitment on the same reef, which is exactly the kind of evidence the 10.4% bleached figure alone cannot convey.

The fish community is dominated by large-bodied predators and grazers, in numbers that make the archipelago's no-take status obvious. **Trevally schools** compatible with *Caranx melampygus* and *Carangoides* fill five frames (P3110555, P3110556, P3110557, P3110558 and, more loosely, P3110561), sometimes thirty or more animals in one shot, the largest aggregations reviewed so far. **Snappers compatible with *Lutjanus bohar*** appear repeatedly at close range (P3110532, P3110533, P3110534, P3110536, P3110540), and emperors or breams compatible with *Monotaxis*, *Gnathodentex* or *Lutjanus gibbus* school over the coral in P3110538 and P3110560. A **grey reef shark compatible with *Carcharhinus amblyrhynchos*** appears in P3110487 and again directly beneath the diver in P3110488. Blue-green chromis compatible with *Chromis viridis* cloud the staghorn thickets in P3110544 and P3110545, and butterflyfishes work the dead framework in P3110542. **The dive's best single macro subject is P3110526** — a large chromodorid nudibranch, white to lilac with orange-yellow spots, a purple mantle margin and gill plume raised, compatible with *Hypselodoris* or *Chromodoris*: the only nudibranch found in the Chagos frames reviewed to date.

**Methodology frames:** P3110488 and P3110532 both show a diver with the white PVC quadrat frame — the latter with a large *Lutjanus bohar* crossing directly in front of the lens as the frame is carried. These, with the BIEG05 series, form a coherent record of the survey method.

<b>Assemblage composition.</b> The Coralscapes and CoralNet figures are given in the cover line above. The 7 pp gap between them (30.1% human points vs 23.3% model area) is the widest of the Egmont sites and is consistent with what the frames show: extensive fine-branched staghorn thickets, which point-counts capture readily but which a mask-based model tends to under-segment where branches interleave with shadow and dead skeleton. The 10.3 pp SD across all three methods is driven mainly by the transect.

**Flags:** (1) **Highest bleaching of the Egmont series (10.4%)**, and the imagery supports it — but the dominant visual signal is *paling across whole stands* (P3110553, P3110537, P3110560) rather than discrete bleached colonies, which a colony-scored metric may under-represent. (2) **P3110542 documents extensive standing dead branching framework** in growth position — logged as mortality, cause unresolved, and explicitly not pooled with active bleaching. (3) Three recruitment-on-dead-substrate frames (P3110506, P3110527, P3110543) — worth keeping for any recruitment analysis. (4) **P3110526 nudibranch** left at family level (Chromodorididae); *Hypselodoris* vs *Chromodoris* is not separable from this angle. (5) Trevally and snapper schools are hedged: *Caranx melampygus* is secure where the blue spotting shows, but mixed *Carangoides* is likely, and the emperor/bream/snapper schools in P3110560/P3110561 could be *Monotaxis*, *Gnathodentex* or *Lutjanus gibbus*. (6) The pale colonies in P3110537 and P3110553 could in principle be a naturally pale morph rather than thermal paling; the frames alone cannot exclude it, though the site's 10.4% figure and the unambiguous P3110562 make thermal paling the better reading. (7) No per-frame depth data.

**Benthic data:** [Download BIEG06 benthic survey data (CSV)](../benthic_data/BIEG06_benthic.csv) — scleractinian cover by genus with full names, plus substrate and algal categories (bare substrate, CCA, turf, macroalgae, invertebrates), from the LOF BIOT-1 survey (Mayfield & Dempsey 2026, *Oceans*, supplemental file S1).