### BIEG03 — Egmont
**Date:** 2015-03-10
**GPS:** 6.69394°S, 71.37862°E · **In-situ temperature:** 29.2°C
**Frames reviewed:** 42 of 42 (100% of the site folder, `BiEg03-finished`)
**Coral cover:** 37.3% (formal transect surveys) · **4.0%** of coral bleached (CoralNet analysis of informal survey images; Mayfield & Dempsey 2026, Oceans)
**Live hard coral cover across methods** (n=42 photos): transect 37.3% · CoralNet points 15.5% · Coralscapes 14.2%. Deviation vs transect -23.1 to -21.8 pp. **Mean of 3: 22.3% ± 13.0.** (SD here reflects systematic method bias, not precision — photo methods read low at high cover; see CHAGOS_MULTIMETHOD_README.md.)  
**Coral genera identified:** 9 scleractinian + 1 hydrocoral + 2 octocoral — *Acropora* (tabular, corymbose, staghorn and digitate), *Pocillopora*, *Porites* (massive domes plus golden digitate colonies), *Montipora*, *Echinopora*/*Turbinaria* (dark whorled foliose stacks), *Favites*/*Dipsastraea*, *Goniastrea*, *Astreopora*, *Platygyra*; hydrocoral *Millepora*; octocorals *Sarcophyton*/*Lobophytum*. Growth-form calls from photographs, given as "compatible with"; the *Echinopora*-vs-*Turbinaria* distinction cannot be settled from these frames.
**Representative photos:** P3100336.jpg, P3100333.jpg, P3100352.jpg, P3100360.jpg, P3100364.jpg

BIEG03 is the largest photo set in the Egmont group and the full 42-frame pass changes its character substantially: this is a **strongly zoned reef, not the "dense reef flat" the previous four-frame description reported**, and the single most important thing the photos show is that the same dive crosses reef of genuinely spectacular quality and reef that is close to barren. The high-cover end is unambiguous — P3100335, P3100336, P3100331 and P3100362 are wall-to-wall lilac, fawn and yellow-green corymbose and tabular *Acropora* with massive *Porites* domes wedged between them, and P3100329 adds a classic *A. hyacinthus*-type table with a powder-blue surgeonfish (*Acanthurus leucosternon*) working across it. The impoverished end is equally clear: P3100300 is a pale carbonate pavement carrying only scattered small faviid domes and a knobby *Porites* across most of the frame, and the long trevally sequence at the dive's end (P3100371, P3100372, P3100374, P3100379) is shot over low-relief rubble and turf-dusted hardground with coral confined to isolated clumps. The transect's 37.3% and the photo methods' 14–16% bracket these two states rather than describing either. Structural variety within the coral-dominated zone is real: P3100352, P3100354 and P3100357 all feature dark, whorled, pale-margined foliose stacks compatible with *Echinopora* or *Turbinaria* — a growth form absent from the neighbouring sites — and P3100356 records a distinctive golden blunt-fingered colony compatible with digitate *Porites*. P3100328 resolves green meandroid brains compatible with *Platygyra* behind a club-branched *Pocillopora*, and P3100347 packs honeycomb-corallite *Favites*/*Goniastrea*, cream *Porites*, corymbose *Acropora* and *Pocillopora* into one macro field. P3100268-style fine detail recurs in P3100301: a thick-branched *Pocillopora* with prominent verrucae, red encrusting sponge and coralline algae, white hydroid plumes compatible with *Aglaophenia*, a wire coral compatible with *Cirrhipathes*, and a cleaner wrasse compatible with *Labroides dimidiatus*.

Bleaching here needs a direct correction to the record. The previous description stated that "one isolated colony stands out as fully bone-white" in P3100333 — **there are four to five fully bleached branching colonies in that frame**, interleaved with normally pigmented brown *Acropora* on the same substrate, and the site carries at least four further bleaching signals the four-frame pass never saw: a white *Pocillopora* beside pigmented neighbours in P3100347; a partially bleached, partially dead *Pocillopora* in P3100346 whose branch tips are bone-white while its basal branches are dark and algal-fuzzed; a pale-to-white branching colony in P3100354; and a conspicuous white colony on the pavement in P3100371. None of this overturns the low 4.0% site figure — the reef is overwhelmingly pigmented — but the pattern is the same growth-form partitioning seen at BIEG02 and BIBL82: branching acroporids and pocilloporids whiten first, massives do not, and P3100346 shows a single colony caught mid-transition from bleached to dead. For an early-March dive, ahead of the event's peak, that is an early-warning signature rather than an impact.

Faunally this is the strongest dive of the three reviewed so far, and it is dominated by one thing: **trevally**. Blue-spotted bluefin trevally compatible with *Caranx melampygus* appear across roughly fourteen frames (P3100359–P3100361, P3100365, P3100366, P3100370–P3100374, P3100378–P3100380), in loose hunting groups of five to ten and repeatedly at close range — P3100360 is a textbook pair, purple-blue and black-speckled, and P3100370 and P3100378 show full schools moving low over the reef. Some individuals in the same frames are brassier and yellow-spotted, compatible with *Carangoides*, so the aggregation may well be mixed-species. Two frames (P3100366, P3100358) catch a diver with a transect pole in the same water as the jacks, confirming these are survey-time observations. Beneath the pelagics the reef holds dense baitfish and silverside clouds around bommies (P3100318–P3100321), fusiliers compatible with *Caesio* or *Pterocaesio* streaming over the tables (P3100337, P3100338), unicornfish compatible with *Naso*, Moorish idols compatible with *Zanclus cornutus* and assorted butterflyfishes (P3100303, P3100332). Two moray eels occupy the macro frames P3100363 and P3100364 — and here a second correction is needed: they are **black with fine yellow speckling**, not "dark green", and are better left at family level than assigned. A large scalloped bivalve shell compatible with *Tridacna* sits on the pavement in P3100353, and P3100330 records a diver holding a clear photoquadrat frame — direct evidence of the quadrat methodology behind this site's numbers.

<b>Assemblage composition.</b> The Coralscapes and CoralNet figures for this site are given in the cover line above; the model-vs-human agreement at BIEG03 is unusually tight (15.5% vs 14.2%), which is expected given how much of the frame set is low-relief pavement where both methods find the same near-absence of coral. The 13.0 pp SD across all three methods is the largest of the Egmont sites and is driven almost entirely by the transect, consistent with the two-habitat structure described above.

**Flags:** (1) **Two corrections to the previous description, both from unreviewed frames:** P3100333 contains four to five bleached colonies, not one; and the morays in P3100363/P3100364 are black with yellow speckling, not "dark green". (2) The claim of a "dense reef flat" understates the site's zonation — roughly half the frames show low-relief pavement with coral under ~10% by eye. (3) P3100346 documents a *Pocillopora* in transition from bleached to dead (white tips, algal-colonised base); logged separately from active bleaching. (4) Trevally identifications are hedged: the schools are probably mixed *Caranx melampygus* and *Carangoides*, and the single fish in P3100359 and P3100365 cannot be separated from a blue-water profile alone. (5) The dark foliose stacks in P3100352/P3100354/P3100357 are firmly one of *Echinopora* or *Turbinaria* but cannot be separated at this resolution. (6) The scalloped shell in P3100353 is read as *Tridacna* but the mantle is not visible, so live-vs-dead is unresolved. (7) No per-frame depth data; zonation is inferred from framing and light.

**Benthic data:** [Download BIEG03 benthic survey data (CSV)](../benthic_data/BIEG03_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).