### BIPB62 — Peros Banhos
**CRD page:** [Peros Banhos Coral Surveys (Apr–May 2015)](https://coralreefdiagnostics.com/peros-banhos-)

**14 Apr 2015**
**GPS:** 5.42721°S, 71.77779°E
**Setting:** protected submerged lagoonal patch reef, 25 m
**Coral cover:** 59.6% (4 formal transects, D2–D5; **algal cover 29.3%**) · **published image bleaching:** 6.9%
**Live hard coral cover across methods:** formal transects 59.6% · CoralNet points 36.7% · Coralscapes masks 38.0% (13 frames). These products have different sampling footprints and denominators and should not be averaged.
**Temperature:** 30.4 °C · **Salinity:** 34.4
**Photo review:** 11 of 46 frames examined — a systematic sample spread across the dive sequence (see Flag 4)
**Representative photos:** P4140559.jpg, P4140622.jpg, P4140649.jpg, P4140617.jpg, P4140584.jpg

BIPB62 is one of the most coral-abundant reefs in the archipelago and the folder name — "great dive" — is not an exaggeration. At **59.6% transect coral cover it ranks 10th of the 109 Chagos sites**, against only 29.3% algae. It is also strikingly clean ground: non-coral invertebrates hold just 1.1% of the benthos (105th of 109) and crustose coralline algae 4.3% (104th of 109), with bare substrate at 10.1%, turf 14.1% and erect algae 8.5%. Almost everything here is living coral or turf.

The assemblage is carried by two genera and only sixteen are non-zero. ***Acropora* holds 22.13% of the benthos and *Echinopora* 19.25%** — together 69% of all coral recorded — with *Montipora* third at 7.00% and *Favia* fourth at 4.94%. Then *Lobophyllia* 1.88%, *Halomitra* 1.25%, *Platygyra* 0.75%, *Pocillopora* 0.50%, *Fungia* 0.44% and ***Porites* at just 0.38%** — a near-absence that is remarkable for Chagos and the single most surprising number in this dataset. *Cynarina*, *Ctenactis*, *Favites*, *Cyphastrea*, *Stylophora* and *Symphyllia* fill out the tail below 0.32%.

**The depth zonation here is as extreme as anything in the Chagos set, and it is a two-genus story.** D2 carries **65.5% coral of which *Acropora* alone is 61.50% — 94% of the coral on that transect**, an effective monoculture. D3 drops to 50.75% and hands over to *Montipora* at 24.50% with *Acropora* second at 19.00%. D4 holds 61.0% and changes genus entirely: ***Echinopora* 23.00% and *Favia* 19.00%**, with *Acropora* down to 3.00%. D5 holds 61.0% and is a second monoculture — ***Echinopora* at 54.00%, 89% of the coral on that transect***, with *Acropora* at 5.00% and *Halomitra* 2.00%, on the site's lowest algal cover of 17.0% and its highest bare substrate at 22.0%. Genus richness collapses at both ends, from ten codes at D3 to three at D5. **The site-level figures of 22.13% *Acropora* and 19.25% *Echinopora* describe no actual transect**: they are the average of a shallow staghorn-and-table reef and a deep *Echinopora* bank.

The photographs document the *Acropora* half of that structure superbly. P4140559 is the defining frame: a near-continuous staghorn and corymbose field running to the limit of visibility with a diver above and fusiliers working over it — the visual match to the 61.5%-*Acropora* D2 transect. P4140622 and P4140611 show the tabular expression of the same zone, large overlapping plates tiled across the slope into blue water, with a big brown massive lobate colony at the margin. P4140649 is the most photogenic: classic pedestalled tables, one a vivid yellow-green, standing above corymbose colonies and purple encrusting framework. P4140627 and P4140660 show the tables mixed with digitate colonies, corymbose thickets and large cream lobate domes.

The deeper, non-*Acropora* community is thinner in the imagery but present. P4140584 holds a large purple-violet foliose colony with strongly radiating septa growing beside pale mint-green plating colonies, a small free-living fungiid and a brown meandroid head — the foliose whorled form is consistent with *Echinopora*, the genus that dominates D4 and D5. P4140598 is a close frame of a single large meandroid brain-coral dome, dark olive with deep sinuous valleys, sitting on clean sand. P4140575 shows the algal side of the reef: abundant bright green *Halimeda*- and *Caulerpa*-type growth across the foreground between pale plating colonies, digitate corals and encrusting purple — the visible counterpart to 8.5% erect algae.

**Condition is the point of tension at this site.** The published image-based bleaching figure is **6.9%, ranking 52nd of the 98 Chagos sites with a value — squarely mid-range** — yet the photographs contain conspicuous bleaching among the tabular *Acropora*. P4140617 shows a run of stark white tables and plates along the slope directly beside fully pigmented tan staghorn thickets, and P4140627 shows a cluster of bright white tables in the middle distance against pigmented tan neighbours. These are coherent, colony-scale, intact-tissue pallor, not growth tips or strobe artefacts. The most likely reconciliation is that the transects and the photographer sampled different parts of the reef, but this has not been tested and is flagged rather than resolved.

<b>Assemblage composition.</b> Formal surveys give 59.6% coral, 29.3% algae and only 1.1% non-coral invertebrates, the coral 69% split between *Acropora* in the shallows and *Echinopora* at depth across just 16 genera. The photographs document the *Acropora* half in detail — staghorn fields, pedestalled tables, corymbose thickets — plus a foliose colony consistent with *Echinopora*, meandroid brain corals, massive lobate domes and abundant green calcareous algae.

**Flags:** (1) **D2 and D5 are effectively single-genus transects** (94% *Acropora* and 89% *Echinopora* respectively). Never quote the site-level 22.13% *Acropora* or 19.25% *Echinopora* as uniform values; neither describes any transect that was actually run. (2) ***Porites* is recorded at 0.38%, yet conspicuous cream-tan massive lobate domes appear in several frames** (P4140655, P4140660, P4140611). Those colonies may be *Favia*, *Echinopora* in massive form, or *Porites* under-recorded by the transect placement — the imagery and the transect list disagree on this component and the disagreement is unresolved. Do not caption those domes as *Porites*. (3) **Photographic bleaching looks worse than the 6.9% site figure implies.** P4140617 and P4140627 show unambiguous white tabular colonies beside pigmented ones. The site value is taken as published; the discrepancy is real and worth checking before either number is used alone. Note also 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 the rank is approximate. (4) **Only 11 of the 46 frames were examined**, sampled systematically across the dive sequence rather than exhaustively; a full pass may add genera, condition records or fauna not listed here. (5) **Severe frame-count mismatch:** the folder holds 46 stills but `chagos_multimethod_cover_by_site.csv` records `n_photos = 13`. The CoralNet (36.7%) and Coralscapes (38.0%) figures rest on roughly a quarter of the available imagery. (6) **Filename collision with BIPB61.** Fifteen frames — P4140628–636, 649, 651, 653, 654, 659 and 661 — exist under identical filenames in both `BIPB62-great dive-finished/BiPb62-CoralNet` and `BiPb61-MANTA! finished`, at different byte sizes, so they are genuinely different images from two cameras working on 14 April. **Any tool that keys on frame filename alone will mix these two sites.** Always carry the folder path, never the bare stem. (7) All BIPB62 imagery sits in the `BiPb62-CoralNet` subfolder; the parent folder holds no stills of its own.

**Benthic data:** [Download BIPB62 benthic survey data (CSV)](../benthic_data/BIPB62_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).