### BIPB110 — Peros Banhos
**CRD page:** [Peros Banhos Coral Survey Sites (Apr 30–May 3, 2015)](https://coralreefdiagnostics.com/peros-banhos-20150430-to-0503)

**30 Apr 2015**
**GPS:** 5.31748°S, 71.92240°E
**Setting:** protected submerged lagoonal channel reef, 20.2 m
**Coral cover:** 39.3% (4 formal transects, D2–D5; **algal cover 41.6%**) · **published image bleaching:** 14.8%
**Live hard coral cover across methods:** formal transects 39.3% · CoralNet points 27.3% · Coralscapes masks 21.3% (45 frames). These products have different sampling footprints and denominators and should not be averaged.
**Temperature:** 30.6 °C · **Salinity:** 34.3
**Photo review:** all 45 frames examined
**Representative photos:** P4300843.jpg, P4300891.jpg, P4300894.jpg, P4300883.jpg, P4300868.jpg

BIPB110 is a coral-abundant, architecturally complex lagoonal channel reef, and among the most compositionally diverse sites in the Chagos set: **23 non-zero coral genera** at 39.3% transect coral cover, which ranks 55th of the 109 sites. It is an *Acropora* reef first and foremost. ***Acropora* holds 16.35% of the benthos — 42% of all coral recorded** — with *Porites* second at 6.64%, then *Favia* and *Symphyllia* both at 2.50%, *Echinopora* 2.45%, *Pocillopora* 2.00%, *Pavona* 1.33% and *Montipora* 0.91%. Below that sits an eleven-genus tail under 0.5%: *Stylophora*, *Leptastrea*, *Goniastrea*, *Astreopora*, *Cyphastrea*, *Goniopora*, *Favites*, *Millepora*, *Platygyra*, *Psammocora* and *Montastrea*. Turf holds 16.1% of the benthos, bare substrate 13.3%, non-coral invertebrates 5.8%, crustose coralline algae 5.5%, erect algae 5.0% and macroalgae 2.2%.

**Coral cover declines steadily with depth while the assemblage reorganises completely.** D2 carries 50.0% coral led by *Acropora* at 25.00% with *Porites* at 16.75%; D3 holds 38.2% with *Acropora* still dominant at 18.40%; D4 falls to 37.0% and *Symphyllia* rises to 9.00% behind *Acropora*'s 16.00%; and **D5 drops to 32.0% and *Acropora* is displaced entirely — *Favia* leads at 9.00%, then *Echinopora* 8.00%, *Acropora* 6.00% and *Herpolitha* 3.00%**, with algal cover jumping to 60.0%. Genus richness peaks in the middle at 17 codes on D3 against six on both D4 and D5. The site-level figures therefore average a shallow *Acropora* reef onto a deep faviid-and-*Echinopora* one and should not be quoted without the depth breakdown.

The reef's three-dimensional structure is unusually conspicuous. Broad plates project over lower colonies, corymbose and branching forms fill intervening spaces, and massive colonies form large rounded buttresses. P4300843 is especially informative: several pale tables overlap like shelves above darker plates and encrusted framework. P4300859 and P4300869 show the same multi-tiered architecture at wider scale, with live colonies distributed across an irregular surface rather than concentrated in one isolated patch. P4300837 establishes a mixed hard-bottom mosaic with sand-filled gaps and P4300868 records the broader broken relief. Sand occupies channels and pockets but does not break the continuity of coral habitat along much of the photographed route.

Bleaching is unmistakable and affects more than one growth form. P4300839 shows a compact branching colony almost uniformly white while retaining intact fine branch structure. P4300843 contains large table-like colonies with equally stark loss of pigmentation, and additional pale branches and plates recur across the middle of the sequence. Some pale rims on otherwise pigmented plates could be normal growth margins or photographic highlights; only colonies with broad, coherent pallor are treated as convincing.

The most dramatic condition feature is the enormous massive colony followed from P4300881 through P4300896. P4300881 shows a partly pigmented tan surface, whereas P4300887 and P4300894 show extensive white tissue interspersed with broad dark red-brown areas. P4300891 demonstrates the colony's exceptional size and the spatial separation between the pale upper surface and the darker areas. The white areas are consistent with severe bleaching. The dark areas appear established and algal or microbial overgrowth is plausible, but the stills do not show an advancing lesion margin, so they are described as areas of apparent prior tissue loss rather than assigned a disease diagnosis.

Mobile fauna add ecological context. P4300883 clearly shows at least two gray reef-shark-type animals resting beneath an overhang, accompanied by small yellow-and-black fishes; adjacent frames give other angles on the same shelter. Their shape and resting posture are compatible with whitetip reef sharks, but the decisive fin-tip and head characters are not equally clear in every image. This is a qualitative occurrence record, not a count of individuals. Encrusting red and purple surfaces are common on exposed framework, small rounded and meandroid colonies occur beside the larger tables, and reef fishes occupy both the water column and crevices. A cucumber-like echinoderm may be present in P4300837, but the angle does not warrant a call.

<b>Assemblage composition.</b> Formal surveys give 39.3% coral, 41.6% algae and 5.8% non-coral invertebrates, the coral 42% *Acropora* in the shallows and led by *Favia* and *Echinopora* at D5. The photographs corroborate the mixture and add what the transects cannot: colony size, vertical layering, bleaching expression across growth forms, and the use of coral ledges by reef sharks.

**Flags:** (1) **The photographs emphasise scenic, coral-dense structures**, so the site should not be read as uniformly matching the densest frames; conversely the transect mean should not obscure the habitat value of the high-relief patches. The gap between a moderate formal cover figure and very dense scenic views is expected, not an error. (2) **D5 is a different reef from D2** — *Acropora* falls from 25.00% to 6.00% and *Favia* and *Echinopora* take over, with algal cover rising to 60.0%. Never quote the 16.35% site-level *Acropora* figure as a uniform value. (3) **Bleaching at 14.8% ranks 14th of the 98 Chagos sites carrying a bleaching value** — high for this archipelago and worth confirming against another method. Note that the published `Mean(%bleaching)` column carries at least one known bad value (BITB58 appears as 22.22% where the corrected figure is 0.77%), so ranks off that column are approximate. (4) **The three cover methods disagree by up to 18 percentage points** (transects 39.3%, CoralNet 27.3%, Coralscapes 21.3%). Do not present a single cover number for this site without the method. (5) The giant massive colony's dark areas are described conservatively as apparent prior mortality; **no disease diagnosis is assigned** and none should be inferred. (6) No crown-of-thorns starfish, discrete feeding scar or progressive disease band was identified in the 45 stills.

**Benthic data:** [Download BIPB110 benthic survey data (CSV)](../benthic_data/BIPB110_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).