Chagos Archipelago - Victory Bank (BIVB81)

Setting

BIVB81 sits on the protected, submerged rim of Victory Bank, inside the lagoon at 29.4 m, surveyed 21 April 2015.

General benthic features

The coral is packed into just 17 genera (88th of 109), and Acropora alone holds 58% of all coral present.

Coral cover

Formal transects recorded 51.7% coral against 44.3% algae — 22nd of 109 Chagos sites for cover — but the algal budget is unusual: 22.8 points of it is sediment-laden turf and 11.8 points macroalgae, with crustose coralline algae at only 4.8%, 103rd of 109 (e.g., Image 1, Image 2).

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The depth profile is the real finding: cover dips to 34.0% at mid-depth, then more than doubles to 78.0% at the deepest transect, where Acropora accounts for 83% of the coral there — so the site-level figure describes no single station. Image-based methods read this reef well below the transects — CoralNet 32.7%, Coralscapes 36.6% against 51.7% — and the three are not interchangeable. 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 44.2% 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 51.7% · CoralNet points 32.7% · Coralscapes masks 36.6% (5 frames). These products have different sampling footprints and denominators and should not be averaged.

Stressors

Published bleaching is 5.1%, and the rank of 69th of 98 comes off the site table's Mean(%bleaching) column, the first CoralNet training run rather than the canonical % bleaching (2nd training) column. The photographs show mostly normally pigmented colonies, several white elements logged as ambiguous rather than confirmed bleaching, no disease, predation, or crown-of-thorns, and a near-continuous whorled foliose stand the transect genus list does not account for (e.g., Image 3, Image 4).

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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.