### BIEG07 — Egmont
**Date:** 2015-03-11
**GPS:** 6.66732°S, 71.36813°E · **In-situ temperature:** 30.0°C — **the warmest reading of the Egmont series**
**Frames reviewed:** 8 of 8 (100% of the site folder, `BiEg07-finished` — the smallest photo set at Egmont)
**Coral cover:** 47.5% (formal transect surveys) · **18.3%** of coral bleached (CoralNet analysis of informal survey images; Mayfield & Dempsey 2026, Oceans) — **the highest bleaching figure anywhere in the reviewed set**
**Live hard coral cover across methods** (n=8 photos): transect 47.5% · CoralNet points 38.8% · Coralscapes 26.8%. Deviation vs transect -20.7 to -8.7 pp. **Mean of 3: 37.7% ± 10.4.** (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 + 1 octocoral — *Pocillopora*, *Acropora*, *Porites*, *Favites*/*Goniastrea*, *Platygyra*, *Goniopora*/*Alveopora* (long extended polyps, hedged); octocoral *Sarcophyton*/*Lobophytum*. Growth-form calls from photographs, given as "compatible with".
**Representative photos:** P3110282.jpg, P3110300.jpg, P3110273.jpg, P3110274.jpg, P3110309.jpg

BIEG07 is the smallest photo set at Egmont and the only one shot almost entirely as close-in macro rather than wide reef scenes — seven of eight frames are within a metre of the substrate. That framing makes it a poor guide to the site's 47.5% transect cover but an unusually good guide to *condition*, and the condition it shows is the worst of the series. The pavement in P3110272 and P3110309 is largely **dead**: crimson and pink crustose coralline algae over grey eroded substrate, green algal turf tufts, black boring holes, loose white *Acropora* branch fragments, and orange-pink encrusting sponges, with live coral reduced to a few small tan colonies at frame edge. P3110283 shows a branching colony with algal-fuzzed dead patches interleaved with live tissue.

Where live coral is present it is diverse at small scale. **P3110273 is the most diverse single macro frame at Egmont**: honeycomb-corallite colonies compatible with *Favites* or *Goniastrea*, a verrucose brown *Pocillopora*, tan *Acropora* branchlets, a grey-white leathery octocoral compatible with *Sarcophyton* or *Lobophytum*, a small green *Porites*, purple encrusting sheets, pink CCA, and a cluster of long extended polyps compatible with *Goniopora* or *Alveopora* — six or seven taxa inside a single field of view. **P3110282 is the site's other standout**: an enormous massive boulder filling the entire frame, healthy and fully pigmented brown.

**Two corrections to the previous description are needed here.** First, that boulder in P3110282 was recorded as "a large, healthy massive/lobed colony compatible with *Porites*". It is not *Porites* — the surface is covered in large **meandroid and cerioid corallites with distinct walls and valleys**, which is a merulinid brain coral compatible with *Platygyra*, *Favites* or *Goniastrea*. *Porites* corallites are minute and give a smooth, finely pitted surface at this magnification; these are centimetre-scale and sinuous. Second, the previous entry described "a clearly bleach-fronted branching colony" in the singular, but **three of the eight frames carry bleaching or paling**: P3110300 is an unambiguous bone-white to cream branching *Acropora* set among fully pigmented brown massives; P3110274 is a cream-yellow *Pocillopora* that has lost most of its pigment; and P3110301 is a second pale tan-cream *Pocillopora* on dead pavement. Three of eight frames is 38% — and while a hand-picked macro set is not a random sample, it is at least consistent with this site carrying the highest bleached fraction (18.3%) in the archipelago set, at the highest recorded temperature (30.0 °C).

**Read together with its neighbours, BIEG07 is the thermal end-member of the Egmont transect.** The six Egmont sites span 28.9–30.0 °C and 0.5–18.3% bleached, and the two extremes line up: BIEG04 at 29.3 °C had zero bleached colonies in 25 frames, while BIEG07 at 30.0 °C has bleaching or paling in three of eight. That is a small sample and the sites differ in more than temperature, but the ordering is worth noting for anyone building the Chagos thermal-response record.

<b>Assemblage composition.</b> The Coralscapes and CoralNet figures are given in the cover line above, and this site has the widest split between them of any Egmont site (38.8% human points vs 26.8% model area, a 12 pp gap). That is an expected artefact of the frame set: with eight close-range macro frames, human point-counts land repeatedly on the coral head that fills the frame, while the model still scores the extensive dead pavement and algal turf around it. **Neither number should be read as a site-level cover estimate here** — the frame set is not a survey, and the 47.5% transect figure is the only defensible cover value for BIEG07.

**Flags:** (1) **Genus correction:** the large boulder in P3110282 is a meandroid/cerioid brain coral (*Platygyra*/*Favites*/*Goniastrea*-type), **not** *Porites* as previously recorded. (2) **Bleaching undercounted previously:** three frames (P3110300, P3110274, P3110301), not one. (3) **Do not use the photo-derived cover figures for this site** — eight close macro frames cannot estimate site cover, and the 12 pp human-vs-model gap is a framing artefact, not a method disagreement worth interpreting. (4) The *Goniopora*/*Alveopora* call in P3110273 rests on extended polyps alone and cannot be taken further; the two genera are separated by tentacle count, not visible here. (5) Extensive dead pavement in P3110272/P3110309 is logged as mortality of unresolved age and cause — this is a macro set with no wide context, so it cannot be scaled to the site. (6) No per-frame depth data.

**Benthic data:** [Download BIEG07 benthic survey data (CSV)](../benthic_data/BIEG07_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).