### BISP96 — Speaker's Bank
**CRD page:** [Speaker's Bank Coral Survey Sites](https://coralreefdiagnostics.com/speakers-bank)

**26 Apr 2015**
**GPS:** 4.96593°S, 72.23623°E
**Setting:** intermediate-exposure submerged rim reef, 34.5 m (windward in the master workbook — see Flag 2)
**Coral cover:** 86.0% (2 formal transects, D3–D4; **algal cover 10.4%**) · **published image bleaching:** 4.2%
**Live hard coral cover across methods:** formal transects 86.0% · CoralNet points 40.5% · Coralscapes masks 36.5% (14 frames). These products have different sampling footprints and denominators and should not be averaged — the spread here is ~49 pp, the largest in the archipelago.
**Temperature:** 29.9 °C · **Salinity:** 33.9
**Photo review:** all 18 frames examined
**Representative photos:** P4260896.jpg, P4260901.jpg, P4260885.jpg, P4260913.jpg, P4260886.jpg

**BISP96 is the highest coral cover in the Chagos survey at 86.0%, rank 1 of 109 — and 10.4% algal cover, the lowest of all 109 sites.** The folder is named `BiSp96-great site-finished`, and the field label is fully borne out by the numbers. Almost nothing here is not coral: non-coral invertebrates hold 1.2% of the benthos, coralline algae 3.7%, turf 2.8%, bare substrate 2.5%, erect algae 2.2% and macroalgae 1.3%.

The assemblage is overwhelmingly one genus across 21 non-zero codes. ***Acropora* holds 70.84% of the benthos — 82% of all coral recorded** — with *Porites* a distant second at 5.66%, then *Montipora* 1.72%, *Favia* 1.62%, *Leptastrea* 1.25%, *Pocillopora* 1.08%, *Platygyra* 1.02%, *Astreopora* 0.82% and *Goniastrea* 0.68%. Eleven further genera fall below 0.5%, among them *Cynarina*, *Cantharellus*, *Echinopora* and *Gardineroseris* — so the reef is not literally monospecific, but it is close.

**Cover rises with depth and so does the dominance.** D3 carries 80.0% coral across 21 genera with *Acropora* at 62.35%; **D4 carries 91.9% — with *Acropora* alone at 79.33%, 86% of the coral on that transect** — across only nine genera. Algal cover halves from 13.7% to 7.0%. Both bands would rank among the highest-cover sites in the archipelago on their own.

Canopy structure is the defining habitat feature. Tables overlap at several levels, creating broad shaded refuges, narrow corridors and a complex understorey. P4260896 shows very large tables filling the foreground, P4260897 through P4260901 show how plate edges repeat across the field, and P4260908 through P4260912 show contiguous tables broken only by small coral heads and encrusted substrate. Colony margins are often intact and pale-tipped and most surfaces remain gold-brown or olive, indicating retained pigmentation across the photographed canopy. Beneath it, red-purple encrusting material, massive colonies, smaller corymbose branches and occasional sand or rubble pockets add the structural and taxonomic diversity that the smaller published categories record.

Fish abundance is visually notable. P4260886 and P4260888 show streams of yellow-striped fusilier-like fishes above the tables and P4260925 records another dense school over the canopy, with darker surgeonfish-like silhouettes and small reef fishes throughout. These are qualitative habitat-use observations, not standardised counts; repeated frames may contain the same individuals and the camera tracks especially scenic schools.

Bleaching is localised, consistent with the low published figure of **4.2% (77th of 98)**. P4260913 contains a compact branching colony uniformly white beneath pigmented tables and darker neighbouring branches, its intact fine structure supporting a high-confidence call. P4260887 holds a branching colony with dark tissue centrally and extensive coherent white branch tips and patches — partial bleaching is plausible, though active growth margins may contribute, so it is retained at medium confidence. Several pale table edges were deliberately excluded because their narrow, regular margins are compatible with normal growth, and bright strobe illumination exaggerates contrast on upward-facing plates.

<b>Assemblage composition.</b> Formal surveys give 86.0% coral, 10.4% algae and 1.2% non-coral invertebrates, the coral 82% *Acropora* and rising to 86% of coral at D4. The photographs document an extensive multi-layered table canopy, encrusted understorey framework, abundant schooling fishes and two colonies with convincing pallor.

**Flags:** (1) **The three cover methods disagree by about 49 percentage points** — 86.0% by transect against 40.5% CoralNet and 36.5% Coralscapes — the widest spread in the Chagos set. On a near-continuous table canopy the point-and-mask products almost certainly under-read overlapping horizontal plates, but this has not been tested. **Never publish 86.0% without the method attached.** (2) **Exposure differs between sources.** `BIOT-1-MASTER-WkBk.xlsx` records *windward*; the published `exposure-revised` column records *intermediate*. The Setting line above uses the revised value for consistency with the rest of this corpus; the master value is preserved here rather than silently harmonised. (3) **Frame-count mismatch:** 18 stills in the folder, all reviewed, but `n_photos = 14` in the multi-method CSV — the CoralNet and Coralscapes figures rest on the smaller set. (4) The `Mean(%bleaching)` source column carries at least one known bad value (BITB58 appears as 22.22% where the corrected figure is 0.77%), so the rank of 77/98 is approximate. (5) No crown-of-thorns starfish, fresh feeding scar, diagnostic disease band or tissue sloughing was identified in the 18 stills; irregular plate margins and small damaged areas occur but cannot be aged or attributed photographically. (6) **NON-CANONICAL BLEACHING RANK — added 2026-08-26.** Any "of 98" bleaching rank above was computed off the site table's `Mean(%bleaching)` column, which equals the **1st** CoralNet training run. Anderson's decision of 2026-08-26 (HOW_TO rule 4e) makes **`% bleaching (2nd training)` canonical**, The file carries TWO pools for it, and they are not interchangeable: a **110-row pool** ranking every dive (revisit dives included, so BIPB70B/72B/69C compete) and a **99-site pool** ranking one value per site. The rank quoted below is on the 110-row dive pool. For this site the canonical value is **4.16%, rank 85 of 110** (1st training: 4.16%, rank 85 of 110). The two runs agree to <0.05 pp on 100 of 110 rows and diverge only on the bleaching-onset dives, so for most sites the distinction changes the rank but not the number.

**Benthic data:** [Download BISP96 benthic survey data (CSV)](../benthic_data/BISP96_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).