Chagos Archipelago - Victory Bank (BIVB108)

Setting

BIVB108 is a protected submerged lagoon-side reef at Victory Bank, 26.5 m, surveyed 30 April 2015 — the published reef-type cell is blank, so no class is asserted.

General benthic features

Twenty-eight genera were recorded, 36th of 109, with Acropora holding 41% of all coral, Porites 17%, and the archipelago's own Ctenella chagius and the blue octocoral Heliopora in the tail (e.g., Image 1).

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Coral cover

Formal transects recorded 45.7% coral against 43.8% algae, 34th of 109 Chagos sites for cover, and the algal budget is turf-led rather than coralline: fleshy turf 13.9% of benthos against coralline algae at 11.9%. Cover nearly doubles down the profile, from 29.5% at the shallowest stratum — where Acropora, Pocillopora, and Porites are nearly co-dominant over turf-and-sediment ground — to 54.1% and 53.4% deeper, where Acropora takes 42-47% of the coral and turf-plus-sediment falls from 15.5% to under half a percent. The image methods read some 27 points below the transects (CoralNet 18.9%, Coralscapes 19.1%) and rest on only three scored frames, so they are fragile and should not be averaged in. Coral cover: 46%. 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 43.8% 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 45.7% · CoralNet points 18.9% · Coralscapes masks 19.1% (3 frames). These products have different sampling footprints and denominators and should not be averaged.

Stressors

Published bleaching is 10.7%, 25th of 98 on the site table's Mean(%bleaching) column, the first CoralNet training run rather than the canonical % bleaching (2nd training) column — and the photographs suggest it is conservative, at least five of 15 frames carrying wholly chalk-white tables beside fully pigmented neighbors; an independent point recount also runs higher, at 12.8% (e.g., Image 2, Image 3, Image 4).

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No disease, predation, or crown-of-thorns was seen.

Comparisons with other data

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