Chagos Archipelago - Salomons Island (BISA91)

Setting

BISA91 is a protected emergent back reef inside Salomon lagoon at 18.2 m, surveyed 24 April 2015 in 30.8 degrees C water, nearly a degree warmer than its neighbors.

General benthic features

Across 27 genera the site row looks unusually even, five genera between 7% and 10% of the benthos with no clear leader — but that evenness is an averaging artifact, and it is the site's real finding: each depth stratum is dominated by a different genus. The shallowest is Acropora ground at 22.8% of the benthos, the next hands over entirely to Goniopora at 20.5%, the third to Porites at 20.3%, and the single deepest transect is 77% Montipora with only eight genera; 84% of the site's Montipora figure comes from that one transect and 79% of its Acropora from two. Only Lobophyllia is abundant across the whole profile.

Coral cover

Formal transects recorded 52.4% coral against 36.3% algae — 21st of 109 Chagos sites for cover, 65th for algae — with turf at 14.6% of the benthos and non-coral invertebrates very low at 2.7%. Image methods read 24 to 25 points below the transects (CoralNet 27.2%, Coralscapes 28.5%) and should not be averaged with them. Coral cover: 52%. Live hard coral measured on the in situ benthic transects of the LOF BIOT-1 expedition (Mayfield & Dempsey 2026, Oceans, supplemental S1), against algal cover of 36.3% of the benthos. The transect figure is this site's authoritative cover value; no image-derived product overrides it. Across methods the same reef reads: transects 52.4% · CoralNet points 27.2% · Coralscapes masks 28.5% (18 frames). These products have different sampling footprints and denominators and should not be averaged.

Stressors

Bleaching on the canonical % bleaching (2nd training) column is 12.37%, 24th of 110 dives, the worst fifth of the archipelago, and both runs agree. Here the photographs back the model: all 18 frames were reviewed and three show unambiguous colony-scale bleaching — a bone-white branching colony beside a pigmented neighbor, a brilliant white massive colony among pigmented ones, and a large polyp-expanded colony pale over most of its living surface. One colony is tan across half its surface and vivid pink across the other with continuous polyp structure between, reading as a chromoprotein response; the rose-pink masses recurring here were logged as sponges by an earlier reviewer and may instead be Lobophyllia, an identification this rebuild offers but does not settle (e.g., Image 3, Image 4).

34

No crown-of-thorns or disease.

Comparisons with other data

No independent survey was made at this exact site; the nearest ones are listed in the table below.