### BIPB67 — Peros Banhos
**CRD page:** [Peros Banhos Coral Surveys (16–17 Apr 2015)](https://coralreefdiagnostics.com/peros-banhos-20150416-to-0417)

**16 Apr 2015**
**GPS:** 5.28098°S, 71.73499°E
**Setting:** intermediate-exposure emergent fringing forereef, 29 m
**Coral cover:** 41.9% (4 formal transects, D2–D5; **algal cover 37.5%**) · **published image bleaching:** 4.9%
**Live hard coral cover across methods:** formal transects 41.9% · CoralNet points 26.1% · Coralscapes masks 26.9% (41 frames). These products have different sampling footprints and denominators and should not be averaged.
**Temperature:** 30.1 °C · **Salinity:** 34.1
**Photo review:** all 44 frames examined — 3 at the top level of the folder plus 41 in the nested `BiPb67-CoralNet` subfolder, which is exactly the 41-frame set scored by the CoralNet-point and Coralscapes methods (see Flag 1)
**Representative photos:** P4160604.jpg, P4160617.jpg, P4160632.jpg, P4160644.jpg, P4160619.jpg

BIPB67 sits mid-pack among the 109 Chagos sites with a published cover value: **41.9% coral cover ranks 45th of 109**, and its **4.9% bleaching figure ranks 78th of 109 — comparatively low, in the lower third of the archipelago**. The genus mix is unusually even for Chagos: **29 nonzero genera were recorded, nearly double BIPB62's 16**, and no single genus reaches even a third of the coral present. *Porites* leads narrowly at **14.68% of the benthos**, with *Acropora* close behind at **12.93%** — together 66% of all coral recorded, but this is a genuinely mixed assemblage rather than a two-genus reef. *Pocillopora* (3.25%), *Montipora* (2.49%), *Pavona* (1.56%) and *Pachyseris* (1.53%) form a substantial second tier, then *Favia* (1.20%) and *Platygyra* (0.99%), with a long tail of twenty-one further genera below 0.6% each — including *Heliopora* at 0.30%, flagged for a codebook naming quirk rather than any photographic uncertainty (Flag 2). All values are percent of total benthos, not percent of coral.

**The depth transects tell a more decisive story than the site mean, and it is a genus handoff rather than a monoculture.** D2, the shallowest transect, carries 49.35% coral of which *Acropora* alone is 25.10% — 51% of the coral on that transect, effectively co-dominant with everything else combined. D3 rises slightly to the site's highest cover, 50.43%, and hands dominance to *Porites* at 18.03% (36% of the coral), with *Acropora* dropping to 10.30% and *Pavona*, *Favia* and *Platygyra* all appearing in the 3–4% range for the only time in the depth series. D4 holds 36.00% coral, again *Porites*-led at 15.60% (43% of the coral) with *Acropora* at 9.30%. D5, the deepest transect, drops further to 32.00% coral — *Porites* still leads at 10.00% (31%), but *Pachyseris* and *Pocillopora* both climb to 6.00%, essentially tying *Acropora*'s 7.00%, making D5 the most evenly distributed transect in the series rather than one dominated by a single genus. Algal cover shows no comparable trend, ranging narrow between 32.5% (D3) and 42.7% (D2). **The site-level figures of 14.68% *Porites* and 12.93% *Acropora* describe no actual transect**: D2 is an *Acropora*-led reef, D3–D5 are each *Porites*-led, and quoting the site mean as uniform would misrepresent every one of the four transects (Flag 3).

The photographs document this same two-part structure directly. A run of frames (P4160604, P4160622, P4160635, P4160647, P4160652, P4160655, P4160657) shows dense, high-cover coral thickets — corymbose and staghorn *Acropora*-type colonies packed edge to edge, dark schools of damselfish threading through the branches, with large tan-olive massive/boulder colonies consistent with *Porites* interspersed at the margins — a plausible visual match to the D2/D3 transects at ~49–50% cover. A second, equally large group of frames (P4160602, P4160603, P4160616, P4160617, P4160633, P4160634, P4160646, P4160649, P4160651, P4160653) shows the opposite: extensive stretches of bare pavement and coral rubble with only scattered tabular colonies standing above the substrate, matching the site's 12.1% bare substrate and 9.8% turf. P4160653 captures this zone directly, with two divers surveying a low-cover pavement flat that plausibly corresponds to the D4/D5 transects at 32–36% cover. Massive *Porites*-type domes recur throughout both zones (P4160600, 620, 621, 625, 638, 644, 648, 657), consistent with the genus's site-wide lead. Crustose coralline algae is conspicuous as extensive pink-purple crust across dead pavement in several frames (P4160605, 617, 636, 649, 658), matching the substrate data's 19.8% CCA — the second-largest non-coral category at the site after bare substrate.

**Condition is broadly consistent with the low published bleaching figure.** Coral pigmentation across all 44 frames is overwhelmingly tan, olive, brown or yellow-green — normal, healthy coloration — and no colony-scale white pallor of the kind documented at other Chagos sites (e.g. BIPB62's tabular *Acropora*) was observed here. The only pale features are the characteristic white growing margins on the outer rims of a few tabular colonies (P4160605, P4160636), a normal growth-tip character in actively extending tables rather than evidence of thermal stress, and it is flagged as such rather than counted toward bleaching (Flag 7). This agrees with the published 4.9% figure sitting in the lower third of Chagos sites.

Fauna is a minor but notable component of the sequence. P4160592 shows a grey reef shark in open water at the reef edge with schooling fusiliers — one of only three top-level frames, all open-water shots that fall outside the CoralNet-scored subset (Flag 1). P4160618 and P4160619 are close-up portraits of a large grouper/coral-trout-type serranid over the reef. Schooling anthias, fusiliers and snapper-type fish recur through most of the coral-dense frames. Two frames (P4160632, P4160658) show a pale mauve/lavender frilly organism on encrusting substrate that is not a scleractinian coral — consistent with a corallimorph or anemone rather than any coral genus (Flag 4). No COTS, disease lesions or predation scars were observed in any frame.

<b>Assemblage composition.</b> Formal surveys give 41.9% coral, 37.5% algae and a comparatively even split across 29 genera, led narrowly by *Porites* (14.68%) over *Acropora* (12.93%) at the site level — but this average conceals a real depth handoff from an *Acropora*-dominant shallow transect to *Porites*-dominant deeper transects. The photographs document both structural modes directly: dense multi-genus coral thickets alternating with extensive low-cover pavement and rubble, plus abundant CCA, a shark, a large grouper, and an unidentified corallimorph-or-anemone-type organism.

**Flags:**
1. **Multi-method scoring subset.** The 41 frames scored by CoralNet points (26.1%) and Coralscapes masks (26.9%) are exactly the nested `BiPb67-CoralNet` subfolder. The 3 top-level frames (P4160592, P4160659, P4160660) are open-water shark/schooling-fish shots with no reef substrate in frame and sit entirely outside the scored set — the multi-method row does not summarize the full 44-frame folder. Formal transects (41.9%) run 15.0–15.8 percentage points above the two imagery methods; do not average across methods.
2. **HELI annotation-provenance.** Per the benthic CSV's own header note, HELI is recorded as *Heliofungia* in the LOF codebook, but Mayfield (2026-08-25) determined the field data are *Heliopora* (blue coral). Labelled *Heliopora* here at 0.30% of the benthos; this is a codebook correction, not a photographic call.
3. **Depth zonation vs. site mean.** Site-level *Porites* 14.68% / *Acropora* 12.93% describe no actual transect: D2 is *Acropora*-dominant (25.10%, 51% of the coral present), while D3, D4 and D5 are each *Porites*-dominant (31–43% of the coral present). Never quote the site averages as characterizing any one depth.
4. **Unidentified organism.** A pale mauve/lavender frilly organism appears in P4160632 and P4160658 on encrusting substrate; not a scleractinian coral, consistent with a corallimorph or anemone. Not counted toward any coral genus.
5. **Low-value annotation frames.** P4160606 and P4160637 are extreme close-up/macro shots of turf and CCA substrate, likely individual point-annotation captures rather than reef-structure documentation; they contribute little to the structural description above.
6. **Notable fauna.** Grey reef shark (P4160592) and a large grouper/coral-trout-type serranid across two consecutive close-up frames (P4160618, P4160619); species not called from the imagery. No COTS, disease lesions or predation scars observed in any of the 44 frames.
7. **No overt bleaching in imagery.** Consistent with the low published 4.9% figure (78th of 109 Chagos sites with a value). The only pale features are white growing margins on a few tabular *Acropora* colonies (P4160605, P4160636) — a normal growth-tip character, not bleaching.
8. **The published bleaching figure is a COMPUTER-VISION product, not an in-situ observation.** It comes from CoralNet annotation of the informal survey images (Mayfield & Dempsey 2026, *Oceans*). Per-image human-vs-model agreement is substantially weaker for bleaching than for cover: r = 0.40 for bleached against r = 0.72 for live hard coral (`CHAGOS_MULTIMETHOD_README.md`). Treat the site bleaching percentage as the weaker of the two published numbers, and never read it as a diver's field estimate.

**Benthic data:** [Download BIPB67 benthic survey data (CSV)](../benthic_data/BIPB67_benthic.csv) — scleractinian cover by genus with full names, plus substrate and algal categories, from the LOF BIOT-1 survey (Mayfield & Dempsey 2026, *Oceans*, supplemental file S1).