Chagos Archipelago - Peros Banhos (BIPB112)

Setting

BIPB112 is an exposed, windward emergent fringing forereef outside Peros Banhos at 32.7 m, surveyed 2 May 2015 (e.g., Image 13).

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General benthic features

Genus richness is high at 30 genera, 16th of 109, with Acropora holding 45% of all coral and a nineteen-genus tail sharing barely 2.4 points of benthos.

Coral cover

Formal transects recorded 45.0% coral against 40.7% algae — 36th of 109 Chagos sites for cover — on hard, clean substrate where sediment does not settle, turf-plus-sediment reaching only 0.66% (e.g., Image 1, Image 5, Image 7, Image 12, Image 18, Image 19).

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The depth profile is an almost complete handover: cover peaks at 56.8% at the shallowest stratum, where Acropora alone holds 75% of the coral, then declines monotonically to just 13% of the coral at the deepest, where Porites (38%) and Montipora (22%) take over. Image methods read 16-18 points below the transects (CoralNet 29.1%, Coralscapes 27.3%). Coral cover: 45%. 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 40.7% 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 45% · CoralNet points 29.1% · Coralscapes masks 27.3% (15 frames). These products have different sampling footprints and denominators and should not be averaged.

Stressors

Bleaching is the headline. Under the canonical % bleaching (2nd training) column it reads 38.2%, the highest value recorded at any Chagos site; the site table's Mean(%bleaching) gives 15.9%, the first CoralNet training run, and a point recount gives 12.7% — three sources, unresolved. The photographs sit with the high end: a meter-scale tiered table gone uniformly bone-white beside pigmented neighbors, a cluster of four or more white tables, a completely white plate next to a partially bleached one (e.g., Image 2, Image 3, Image 8, Image 9, Image 11, Image 16).

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No disease, predation, or crown-of-thorns was seen; a school of trevally-type jacks was photographed off the wall, and the folder name claims a whale shark that no still supports (e.g., Image 6).

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Comparisons with other data

No prior survey data from this site. If you would like to share yours, please email us.