### BISA102 — Salomon
**CRD page:** [Salomon Islands Coral Survey Sites (Apr 26–30, 2015)](https://coralreefdiagnostics.com/salomon-20150426-to-0430)

**28 Apr 2015**
**GPS:** 5.36938°S, 72.21379°E
**Setting:** exposed emergent forereef outside the lagoon, 32.8 m (the `exposure-original` cell is blank — see Flags)
**Coral cover:** 30.9% (4 depth transects, D2–D5; **algal cover 30.6%**) · **published image bleaching:** 19.2%
**Live hard coral cover across methods:** formal transects 30.9% · CoralNet points 20.0% · Coralscapes masks 20.1% (35 frames). These products have different sampling footprints and denominators and should not be averaged.
**Temperature:** 29.7 °C · **Salinity:** 34.4
**Photo review:** 20 of 36 jpg stills examined — an 18-frame systematic every-second sample spanning the whole dive sequence from P4280838 to P4280896 (P4280838, 840, 842, 845, 847, 849, 851, 860, 862, 864, 877, 883, 885, 887, 889, 891, 894, 896), plus two adjacent frames (P4280873, P4280881) pulled in to check a suspected blue-light frame. **P4280877 is a fluorescence/blue-light frame and was excluded from colour-based condition scoring** (see Flags).
**Representative photos:** P4280847.jpg, P4280881.jpg, P4280873.jpg, P4280885.jpg, P4280840.jpg

BISA102 is a deep exposed forereef on the outside of Salomon atoll, surveyed at 32.8 m, and its published numbers put it just below the archipelago median for structure — **30.9% coral against 30.6% algae, ranking 75th of 109 Chagos sites for coral cover and 87th of 109 for algal cover, i.e. in the lowest quartile for algae.** **The number that actually defines this site is neither of those: it is non-coral invertebrate cover (PITS) at 31.3% of total benthos, which slightly exceeds the site's own coral cover.** The rest of the substrate budget is unremarkable — crustose coralline algae 12.5% (62nd of 109), fleshy turf 8.3% (69th of 109), turf-and-sediment 5.8%, bare substrate 7.2%, macroalgae 3.7%, encrusting algae 0.4% and cyanobacteria 0.02%. A reef where sponges, anemones, soft corals and bivalves hold as much ground as the scleractinians is unusual in this dataset and it is the single most useful thing to know about the site.

Coral cover is spread across **24 nonzero genera, 61st of 109 Chagos sites for genus richness — middling** — but the assemblage is heavily concentrated and, unusually for Chagos, **not led by *Acropora***. The 24 genus percentages sum to 30.8688% of the benthos, an exact match to the published cover figure. All values below are percent of total benthos, not percent of coral. ***Porites* dominates at 14.11% of the benthos — 46% of all the coral present** — followed by *Pocillopora* 6.14% (20%) and only then *Acropora* 3.47% (11%); those three hold 77% of the coral recorded. Behind them, *Montipora* 1.13%, *Pavona* 1.11%, *Montastrea* 0.96%, *Stylophora* 0.87% and *Favia* 0.75%, then *Leptastrea* 0.47%, *Goniastrea* 0.34%, *Psammocora* 0.33% and *Echinopora* 0.26%. A tail of twelve further genera each sits below 0.20%: *Favites*, *Platygyra*, *Gardineroseris*, *Heliopora*, *Isopora*, *Leptoseris*, *Alveopora*, *Fungia*, *Lobophyllia*, *Astreopora*, *Cantharellus* and *Goniopora*. An assemblage in which massive *Porites* holds nearly half the coral is characteristic of deep, high-energy forereef, and it is exactly what the photographs show.

**The four depth transects turn the site's two defining features into a single trend: *Porites* takes an ever-larger share of a shrinking, less species-rich assemblage with depth, while non-coral invertebrates dominate the shallowest and deepest stations outright.** D2, the shallowest station sampled, carries 24.25% coral against 31.25% algae — and **38.5% non-coral invertebrates, more than the coral and the algae each**; *Porites* leads at 9.50% (39% of that transect's coral) with *Pocillopora* 5.75%, *Acropora* 2.50%, *Montastrea* and *Pavona* 1.75% each and *Leptastrea* 1.00% (11 genera). D3 is the site's best transect on every axis: **coral cover rises to 37.23%, non-coral inverts fall to 24.55%, and genus count reaches 22 of the site's 24 genera**; *Porites* 12.72%, *Pocillopora* 8.40%, *Acropora* 3.33%, *Stylophora* 3.27% — its highest value in the profile, nearly four times the site mean — then *Favia* 2.05%, *Montipora* 1.60% and *Pavona* 1.27%, with the minor tail — *Heliopora*, *Gardineroseris*, *Goniastrea*, *Platygyra*, *Leptoseris* and *Lobophyllia* among them — filling out the transect; **two genera, *Isopora* and *Alveopora*, occur here and nowhere else at the site** (as do *Fungia* and *Goniopora*). At D4 cover eases to 31.00% and algae peaks at 41.27%, but **the *Porites* share climbs to 16.20% — 52% of that transect's coral** — ahead of *Pocillopora* 4.40% and *Acropora* 4.07%, on 19 genera. **D5, the deepest station, is the extreme: coral cover stays at 31.00% but the assemblage collapses to just 5 genera, non-coral invertebrates hit 39.0%, and *Porites* alone reaches 18.00% of the benthos — 58% of that transect's coral.** Only *Pocillopora* (6.00%), *Acropora* (4.00%), *Montipora* (2.00%) and *Goniastrea* (1.00%) accompany it; algal cover falls to 17.0%, the lowest in the profile, and bare substrate rises to 13.0%. All four depth rows account for 100% of the benthos with no shortfall. **The site-level figure of 24 genera describes no single transect** — it is a union across four stations of which the deepest carries five.

The photographs confirm both the *Porites*-led coral assemblage and the extraordinary invertebrate component. Massive, lobate and helmet-shaped colonies consistent with *Porites* are the dominant structural element in P4280885 (a single tan colony well over a metre across), P4280860, P4280862 and P4280894, and pale grey-green massive colonies of the same growth form recur in close-up in P4280842 and P4280847. **The invertebrate signal is unmistakable in the imagery: P4280845 and P4280873 show clusters of large magnificent-anemone-type actinians with deep purple columns and cream-yellow tentacles, with anemonefish among them; P4280864 shows purple-stalked soft-coral colonies with white polyp crowns spread across the pavement; P4280842 and P4280849 show bright red and orange encrusting sponges and red wire/whip gorgonians; P4280838 and P4280840 show a large gorgonian sea fan on the deep slope; and P4280889 and P4280891 record giant clams (*Tridacna*-type) with blue-grey and iridescent mantles set into the pavement.** P4280896 documents the other end of the habitat range — a near-barren rubble and sand plain with only scattered small colonies, consistent with the low-diversity deepest transect. Image-based genus and species calls are tentative throughout and no cover figure is derived from them.

**Condition is the site's most serious finding, and here the imagery and the published figure agree.** The published image-based bleaching value is **19.2% — the 8th-highest of the 98 Chagos sites carrying a value, in the top decile of the archipelago for bleaching severity.** Unambiguous bleaching is visible in the frames rather than marginal. **P4280847 is the clearest single record: a compact branching colony (growth form consistent with *Pocillopora*) that is uniformly stark white across every branch, sitting directly beside olive, tan and pink pigmented colonies of comparable size in the same frame — a within-frame contrast that exposure or strobe artefact cannot explain.** **P4280881 shows three adjacent white branching colonies together**, again against a fully pigmented red-and-pink substrate. **P4280885 carries a bright white corymbose colony in the lower right against a normally pigmented massive *Porites*.** A small white branching colony also appears in the close-up of P4280842, and a further white colony sits mid-frame in P4280894. These are logged as frame-level bleaching records; they support the published value but do not generate a replacement percentage, and none was calculated. The white colonies are recorded as bleaching rather than disease because no characteristic lesion margin or advancing tissue-loss band is visible on any of them. **No crown-of-thorns starfish, no *Drupella* aggregation and no predation scarring were seen in the 20 frames examined.**

Fauna is abundant and includes several notable records. **P4280840 documents a requiem shark in open blue water above the deep slope, with conspicuous white margins on the dorsal, pectoral and caudal fins — a pattern consistent with a silvertip shark**, though a single frame does not confirm the species. **Two giant morays (*Gymnothorax javanicus*-type) are photographed under ledges in P4280849 and P4280851**, the second being cleaned by a wrasse. **An octopus is recorded in a crevice in P4280887**, and giant clams in P4280889 and P4280891. Snappers, surgeonfishes, anthias, damselfishes and anemonefish appear throughout. A diver with a camera rig is visible in P4280883 and P4280885 — standard field documentation, not a data concern.

<b>Assemblage composition.</b> Formal transects give 30.9% coral against 30.6% algae across 24 nonzero genera, but the assemblage is *Porites*-led rather than *Acropora*-led: *Porites* (14.11%) holds 46% of all coral, with *Pocillopora* (6.14%) and *Acropora* (3.47%) behind it and 77% of the coral in those three genera. Non-coral invertebrate cover (31.3%) slightly exceeds coral cover site-wide and exceeds it outright at the shallowest and deepest transects (38.5% at D2, 39.0% at D5). The depth profile shows the *Porites* share of coral rising steadily with depth — 39%, 34%, 52%, 58% — while genus richness collapses from 22 genera at D3 to just 5 at D5. The photographs corroborate a *Porites*-dominated deep forereef with an exceptional invertebrate community of anemones, soft corals, sponges, gorgonians and giant clams, and provide direct frame-level evidence of the bleaching behind this site's top-decile published figure of 19.2%.

**Flags:** (1) **P4280877 is a FLUORESCENCE / BLUE-LIGHT frame** — a close-up of an *Acropora*-type colony glowing cyan-green under blue excitation. **It must be excluded from any colour-based condition scoring or CV cover annotation**, since a fluorescence frame will be scored as neither healthy pigment nor bleached tissue by a normal-light model. It joins the known list (BISA104 P4290914–915, BISA103 P4290870) and should be added to it. Whether this frame is inside the 35-frame CV scored subset was not verified and should be checked. (2) **Bleaching is high and photographically confirmed.** The published figure of 19.2% ranks 8th of 98 — top decile — and at least five sampled frames (P4280842, P4280847, P4280881, P4280885, P4280894) show stark white colonies against pigmented neighbours in the same frame. This is a genuine bleaching site, not an artefact. The rank is approximate: the `Mean(%bleaching)` column carries at least one known bad value (BITB58 listed at 22.22% against a corrected 0.77%), so the ordering near the top of that column has not been independently audited. (3) **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. (4) **Non-coral invertebrate cover (PITS 31.3%) exceeds coral cover (30.9%) at this site**, and exceeds it decisively at D2 (38.5% vs 24.25%) and D5 (39.0% vs 31.0%). Any analysis that treats the benthos here as a coral–algae system will misdescribe roughly a third of the substrate. The imagery identifies the components as anemones, soft corals, encrusting sponges, gorgonians and giant clams. (5) **The `exposure-original` cell is BLANK** in `Chagos benthic data by site (n=109).csv`; the header reports `exposure-revised` = exposed. No class was invented. (6) **Genus richness is a D3 artefact:** D3 carries 22 of the site's 24 genera, against 11 at D2, 19 at D4 and **only 5 at D5** (the two genera absent from D3, *Astreopora* and *Cantharellus*, occur at D4 only). Six genera occur on one transect only: *Alveopora*, *Fungia*, *Goniopora* and *Isopora* at D3, *Astreopora* and *Cantharellus* at D4. A site-level genus count of 24 badly overstates what a diver would see at the deepest station. (7) **Multi-method deviation is consistent but large.** CoralNet points (20.0%) and Coralscapes masks (20.1%) sit ~11 percentage points below the formal-transect figure (30.9%; published deviation range −10.9 to −10.8 pp). The two CV products agree with each other to 0.1 pp and disagree with the transect identically, which is worth noting but is not evidence that either is right. Do not average the three figures; the transect value is ground truth for cover. The high non-coral invertebrate cover is a plausible contributor to CV under-reading here and is worth testing. (8) **Frame-count mismatch:** the photo folder holds 36 jpg stills but `chagos_multimethod_cover_by_site.csv` records `n_photos = 35` for the CV comparison — a one-frame discrepancy of unclear origin. The CoralNet and Coralscapes figures rest on that 35-frame scored subset, not on the 36 frames in the folder or the 20 reviewed here. (9) **No COTS, no disease lesions, no *Drupella* and no predation scarring were observed** across the 20 frames examined — an explicit absence-of-evidence finding, bounded by the 16 frames not reviewed. (10) **Notable fauna records:** a requiem shark with white fin margins consistent with a silvertip shark (P4280840, species unconfirmed from one frame); two giant morays (P4280849, P4280851); an octopus (P4280887); giant clams (P4280889, P4280891); and anemonefish-occupied magnificent-anemone-type actinians (P4280845, P4280873). (11) **A diver and camera rig are visible in P4280883 and P4280885** — standard field documentation, not a data issue. (12) **Formal replication is `N Rows` = 4**, and there is no D1 transect, so the shallowest reef zone is unsampled. The depth codes D2–D5 carry no metre boundaries in `Chagos benthic data by site-depth (n=336 rows).csv`; they are ordered shallow-to-deep stations, and the 32.8 m in the header is the site-level survey depth, not the depth of any one transect. (13) **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 **19.18%, rank 15 of 110** (1st training: 19.18%, rank 11 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 BISA102 benthic survey data (CSV)](../benthic_data/BISA102_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).