Chagos Archipelago - Peros Banhos (BIPB74)

Setting

BIPB74 is a lagoonal patch reef (the nearest class on the LOF habitat map is lagoonal pinnacle reefs, massive coral dominated) inside Peros Banhos (dived to 25.5 m): 63% living coral against 32% algae, with bare substrate almost absent at 1.2% (e.g., Image 1).

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General benthic features

Across 25 genera it is effectively a single-genus reef, Acropora holding 70% of all coral, Pavona the only other genus above 2.3% (e.g., Image 3, Image 8, Image 11).

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The depth profile splits that average three ways: the shallowest stratum is the mixed one, Acropora under half the coral and Pavona a quarter of it; the middle is a near-monoculture at 71% cover with Acropora at 86%; the deepest brings in Porites and Montipora.

Coral cover

• Reference: Mayfield & Dempsey (2026)
• CoralNet submission package
• 63%, against 32% algae, from the 18 April LOF transect survey (the mean of all of this station's transects; survey published in Mayfield & Dempsey 2026, suppl. S1).
• Transect mean 63 ± 4.6% SE (n = 20 transects; Living Oceans Foundation per-transect benthic data); the headline above is this all-transect mean, and the published station value, which weights each depth equally, is 62% (Mayfield & Dempsey 2026, Oceans, suppl. S1).
• Image-based estimates in the method table are listed for comparison only; the transect figure is this site's cover value. They pool frames from both dives.

Stressors

On 18 April published bleaching was 5.3% (Mayfield & Dempsey 2026, suppl. S1), and the tables in the cited photograph are tan and pigmented (e.g., Image 2).

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The 16 frames from the 1 May revisit show a reef visibly worse, a mosaic of whitened tabular and branching Acropora and wholly white Pocillopora and free-living fungiids, while the dark maroon foliose plates stay fully pigmented throughout (e.g., Image 9, Image 10, Image 11, Image 15, Image 16).

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No crown-of-thorns or disease in either dive. Anderson's sampling sheet records 11 colonies sampled here at 14.3–25.4 m: four Pocillopora damicornis and one P. acuta by RFLP; three Seriatopora hystrix by field call; three Pocillopora sp. sampled for a collaborator (field calls); the condition notes run from healthy to 100% bleached. Pocillopora acuta colonies from this archipelago were analyzed in Thomas et al. (2026, Global Ecology and Biogeography 35:e70305, https://doi.org/10.1111/geb.70305). The Living Oceans Foundation transects here recorded 0.1% cyanobacteria and 0.2% recently dead coral.

Fish and other fauna

A hawksbill turtle was photographed resting on a bed of pale tables.

Comparisons with other data

Apart from the Living Oceans Foundation survey shown here, we found no other surveys at this site as of 2026. If you would like to share yours, please email us.

Dive record

The site was dived twice.

Other notes

The 1 May revisit thirteen days later was photographed but never scored, so no May bleaching value exists for this site. Reef type follows Anderson's field sheet; on the LOF habitat map the pin falls on 'lagoonal floor - barren', 48 m from the nearest mapped reef, 'lagoonal pinnacle reefs - massive coral dominated', which the transects confirm is reef; the note describes 'a series of mostly deep coral pinnacles in the lagoon'. Anderson's field sheet (LOF fellowship 2016 workbook) records 'lagoonal patch reef', 'leeward'; the expedition's 933-site table classes the station as 'protected' (patch reef).