Chagos Archipelago - Peros Banhos (BIPB71)

General benthic features

BIPB71 is an Acropora reef and very little else. Transect counts put Acropora at 49% of the benthos — 79% of live coral — with Porites 7.0% (11%) a distant second. The remaining nine genera make up under 10% of live coral, as shares of the benthos: Pocillopora 2.0%, Pavona 1.1%, Montipora 1.0%, Favia 0.6%, Platygyra 0.4%, Ctenella 0.3%, Millepora 0.2%, and Stylophora and Symphyllia 0.1% each. Richness is 11 genera; H′ = 0.83, Simpson = 0.36, J′ = 0.34. Very high cover on very few genera. Total algae is 27%, and plain turf dominates it — 17%, 61% of all algae — with CCA 5.0%, sediment-laden turf 2.7%, macroalgae 2.3%, erect 0.7%, cyanobacteria 0.1%. Bare substrate 4.2%, pavement 13%, sand 3.3%, rubble 2.9%, non-coral invertebrates 6.0%.

Coral cover

• Reference: Mayfield & Dempsey (2026)
• CoralNet submission package
• The nine transects average 62% ± 13 SD (the raw, unweighted transect mean) over a 40–84% range, none below 40%; the published site cover, which weights each depth equally (one depth had a single transect), is 63% (Mayfield & Dempsey 2026, Oceans, supplemental S1).
• Coral cover: 62%.
• Live hard coral measured on the in situ benthic transects of the LOF BIOT-1 expedition (the mean of all of this station's transects), against total algal cover (all algal groups) of 27% of the benthos.
• The transect figure is this site's authoritative cover value; no image-derived product overrides it.

Stressors

The mortality signal is the second story, and it is not small. Dead coral averages 16% ± 12 SD across the nine transects, and recently dead coral averages 2.0%, with one transect at 12%. Two transects carry 31% and 35% dead coral. Without imagery there is no telling whether that dead coral is storm or predation damage, an Acropora die-back in progress, or the standing skeleton a dense tabular stand always carries. It is the one thing here that the available data cannot resolve. The Living Oceans Foundation transects here recorded 0.1% cyanobacteria.

Comparisons with other data

Apart from the Living Oceans Foundation survey shown here, we found no other surveys at this site as of 2026. Within 5 km, three independent stations recorded station-year means of 21–26% hard coral cover in 2015; the nearest, XL Catlin Seaview Survey at transect 36010, 1.38 km away, read 26% in 2015.

Other notes

BIPB71 rests on nine transects across two depth strata, 900 points — all 100-point, so no point-weighting issue. Eight transects sit in D3 and only one in D4, so the site is effectively single-depth and the depth profile is untestable (D3 62%, D4 64%).

No underwater photographs from this station are on file.