### BISP89 — Speaker's Bank
**CRD page:** [Speaker's Bank Coral Survey Data](https://coralreefdiagnostics.com/speakers-bank)

**24 April 2015**
**GPS:** 4.95175°S, 72.38296°E
**Setting:** protected submerged lagoonal patch reef, 30.8 m
**Coral cover:** 33.2% (3 depth transects, D2–D4; **algal cover 54.6%**) · **published image bleaching:** 9.2%
**Live hard coral cover across methods:** formal transects 33.2% · CoralNet points 8.3% · Coralscapes masks 8.9% (8 frames). These products have different sampling footprints and denominators and should not be averaged.
**Temperature:** 29.9 °C · **Salinity:** 34.3
**Photo review:** all 13 jpg stills examined (the folder also holds one unreviewed video clip — see Flags)
**Representative photos:** P4240838.jpg, P4240856.jpg, P4240870.jpg, P4240878.jpg, P4240887.jpg

BISP89 is a deep, protected lagoonal patch reef inside Speaker's Bank, and it is an **algae-dominated site rather than a high-cover one: 33.2% coral against 54.6% algae, ranking 68th of 109 Chagos sites for coral cover but 14th of 109 for algal cover.** The algal budget is turf-weighted rather than coralline-weighted, which is the reverse of the pattern at the higher-cover Great Chagos Bank sites: fleshy turf (PTTS) reaches 17.8% of total benthos, the **9th-highest turf value of the 109 sites**, while crustose coralline algae (PCCATS) accounts for 20.8% (18th of 109). Sediment-filled interstices are also prominent — PMTS 11.5% and PITS 8.0% — against only 4.2% bare substrate (PB) and 3.7% PTSTS. This reads as a soft, sediment-influenced lagoonal reef where turf and sediment share the space coral does not hold.

Coral cover is spread across **29 nonzero genera (23rd of 109 Chagos sites for genus richness)**, and the 29 genus percentages sum to 33.1833% of the benthos — an exact match to the published cover figure. All values below are percent of total benthos, not percent of coral. *Acropora* leads at 8.17% of the benthos (25% of the coral present), followed by *Porites* 4.72% (14%), *Stylophora* 4.33% (13%), *Montipora* 3.24% (10%) and *Favia* 2.98% (9%) — together these five genera account for 71% of all coral recorded. *Pocillopora* (2.28%), *Platygyra* (1.30%), *Goniastrea* (1.29%) and *Lobophyllia* (0.88%) follow, then a tail of 20 further genera — *Favites*, *Pavona*, *Cyphastrea*, *Montastrea*, *Fungia*, *Astreopora*, *Galaxea*, *Leptastrea*, *Symphyllia*, *Turbinaria*, *Hydnophora*, *Psammocora*, *Echinopora*, *Leptoseris*, *Gardineroseris*, *Goniopora*, *Seriatopora*, *Mycedium*, *Cantharellus* and *Echinophyllia* — each under 1% of the benthos.

**The three depth transects show coral cover climbing and algal cover falling with depth, and the leading genus handing over twice on the way down.** D2, the shallowest station sampled, carries the lowest coral cover of the profile at 27.8% against the site's highest algal cover, 67.5% — and it is strongly *Acropora*-dominated, with *Acropora* alone at 15.00% of the benthos, 54% of all the coral on that transect, ahead of *Porites* 3.25%, *Pocillopora* 2.75%, *Stylophora* 2.25%, *Favia* 1.25% and *Montipora* 1.25%. At D3 cover rises to 35.4% and algae falls to 53.8%, and **the lead changes hands: *Stylophora* takes over at 8.10%** (23% of the coral there) ahead of *Acropora* 7.15%, with *Favia* 3.45%, *Montipora* 3.27%, *Porites* 2.40% and *Lobophyllia* 2.38%. At D4, the deepest station, cover peaks at 36.5% and algae drops to 42.6%, and **the lead changes again — *Porites* at 8.50%** (23% of that transect's coral), then *Montipora* 5.20%, *Favia* 4.25%, *Goniastrea* 3.50%, *Pocillopora* 3.50% and *Stylophora* 2.65%; *Acropora* falls out of the top six entirely. **The site-level figures of 8.17% *Acropora* and 4.33% *Stylophora* therefore describe no single transect**: they average an *Acropora*-dominated shallow station against a *Porites*/*Montipora* deep one, with *Stylophora* peaking only in the middle.

The photographs — all 13 stills in the folder — show a heterogeneous patch reef rather than a uniformly coral-covered field, which is consistent with a site whose cover swings from 27.8% to 36.5% across three transects. The underwater sequence begins with high-relief, coral-abundant patches carrying lavender-to-magenta branching colonies, plates, massive heads and abundant fishes; later views open onto broader pavement, rubble and low-relief plate fields with scattered compact colonies. P4240856 and P4240870 represent the more structurally complex end of the sequence, whereas P4240878 and P4240887 show the open plate-and-framework habitat. P4240838 is a topside context frame with a rainbow over the bank. Growth-form diversity in the imagery matches the genus list — branching and plating colonies are conspicuous, with massive and submassive forms interspersed — but genus-level identifications from the images remain tentative.

**Condition reads as moderate.** The published image-based bleaching figure is **9.2%, ranking 34th of the 98 Chagos sites carrying a value** — the upper third for bleaching severity, though not extreme. Some colonies and plate margins appear pale in the stills, but the retained photographs do not show an unambiguous, close, fully white colony comparable with the stronger photographic records at neighbouring sites, and pale substrate, flash illumination and naturally light branch tips were not converted into additional bleaching flags. The published value therefore remains the sole site-level percentage. No crown-of-thorns starfish, disease lesion, tissue-loss margin or predation scarring was identified in the 13 stills; broken and encrusted framework occurs, but no cause can be assigned from photographs.

Fish are conspicuous throughout the underwater sequence. Large mixed schools cross the plate fields in P4240878 and P4240887, while smaller reef fishes occupy the branching habitat in the earlier frames. These are qualitative observations from non-standardized site photographs and are not abundance estimates.

<b>Assemblage composition.</b> Formal transects give 33.2% coral against 54.6% algae — a comparatively algae-dominated, turf-weighted lagoonal reef (9th-highest turf of 109 sites) — across 29 nonzero genera led by *Acropora* (8.2%), *Porites* (4.7%), *Stylophora* (4.3%), *Montipora* (3.2%) and *Favia* (3.0%). The three-transect depth profile shows cover rising from 27.8% at D2 to 36.5% at D4 as algal cover falls from 67.5% to 42.6%, with the leading genus passing from *Acropora* (shallow) to *Stylophora* (mid) to *Porites* (deep). The photographs document this same structural range — coral-abundant branching patches alternating with open plate-dominated pavement and rubble — plus conspicuous schooling fishes, and give no basis for a new bleaching percentage or a frame-specific disease or COTS record.

**Flags:** (1) **Multi-method deviation is large.** CoralNet points (8.3%) and Coralscapes masks (8.9%) sit 24–25 percentage points below the formal-transect figure (33.2%, deviation range −24.9 to −24.3 pp). Do not average the three figures; the transect value is treated as ground truth for cover. (2) **The CV figures rest on an 8-frame scored subset**, not the 13 stills reviewed here — never print the folder frame-count beside a CoralNet/Coralscapes value. (3) **The CoralNet points figure is a CV product, not verified ground truth**; point-annotation data corpus-wide is roughly 76% unconfirmed machine output. (4) **Formal replication is thin: `N Rows` = 3** for this site, so the site-level cover and algal figures rest on three depth rows. (5) **No D1 transect exists for this site** — the profile starts at D2, so the shallowest reef zone is unsampled and the site-level means are not comparable with sites carrying a D1 row. (6) **The depth codes D2–D4 carry no metre boundaries in `Chagos benthic data by site-depth (n=336 rows).csv`** — they are ordered shallow-to-deep stations, and the 30.8 m in the header is the site-level survey depth, not the depth of any one transect. (7) **No unambiguous bleaching was resolvable from the photographs**; the 9.2% published figure stands alone and was not recalculated here. Any rank off the `Mean(%bleaching)` column is approximate — that column carries at least one known bad value (BITB58 listed at 22.22% against a corrected 0.77%). (8) **No COTS, disease, or predation scarring was observed** across the full 13-frame review — an explicit absence-of-evidence finding, not an omission. (9) **The folder also holds one unreviewed video clip** (P4240890.MOV, 26.8 MB), outside the scope of this still-photo review. (10) **P4240838 is a topside frame**, not benthic, and contributes no substrate or condition information. (11) **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 BISP89 benthic survey data (CSV)](../benthic_data/BISP89_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).