Chagos Archipelago - Salomons Island (BISA94)

Setting

BISA94 is a lagoonal patch reef inside Salomon atoll, leeward on Anderson's field sheet, surveyed 25 April 2015 on a dive to 18.6 m.

General benthic features

Bare substrate and invertebrates are both under 5%, so the benthos is essentially coral or fleshy algae. Across 28 genera the assemblage is massive- and fleshy-dominated: Porites 25% of the benthos, 48% of all coral, and Goniopora 13%, three-quarters of the coral between them, while Acropora is effectively absent at 0.1%.

Coral cover

• Reference: Mayfield & Dempsey (2026)
• CoralNet submission package
• Formal transects recorded 52% coral against 39% algae, and here algae means genuine fleshy growth rather than pavement: turf alone is 19% of the benthos, with macroalgae a further 11% and coralline algae only 7.8%.
• The depth finding is a collapse: 63% coral at the shallowest stratum, 47% at the next, then 11% against 80% algae at the deepest, where only two genera remain on the entire transect.
• Transect mean 52 ± 5.4% SE (n = 15 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 40% (Mayfield & Dempsey 2026, Oceans, supplemental S1).
• 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 39% of the benthos.
• Image-based estimates (CoralNet, DINOv3, CoralSCOP, and Claude) are listed in the method table for comparison only; the transect figure is this site's cover value.

Stressors

Published bleaching is 2.8% (CoralNet analysis of the survey images; Mayfield & Dempsey 2026, suppl. S1). Only two photographs exist from this dive, and neither shows crown-of-thorns or disease (e.g., Image 1, Image 2).

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Anderson's field record describes the condition: all four Seriatopora hystrix sampled were 100% bleached, most P. acuta looked healthy though one was bleached, and the notes record many bleached corals in the shallows (see Dive record below). The Living Oceans Foundation transects here recorded no cyanobacteria and 0.1% recently dead coral.

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, seven independent stations recorded station-year means of 6.8–63% hard coral cover between 2006 and 2020; the nearest, XL Catlin Seaview Survey at transect 36015, 0.66 km away, read 28% in 2015.

Dive record

Anderson's afternoon dive on 25 April 2015 entered the water at 13:57 and lasted 63 minutes, to a maximum depth of 18.6 m (the field sheet); Anderson's notes describe an incredibly murky lagoon site with terrible visibility, high coral cover in places on a Porites cylindrica framework from 15 to 18.5 m, calm, warm water, all Seriatopora bleached, most P. acuta looking okay though one was bleached, many bleached corals in the shallows, and no pocilloporids other than P. acuta. Anderson sampled seven Pocillopora acuta colonies (six confirmed by RFLP; CHPd129 by field call): CHPd128 (collected 14:05 at 18.5 m; small, healthy, under a year old), CHPd129 (14:12, 16.5 m; pale lemon yellow on P. cylindrica rubble, likely healthy), CHPd130 (14:33, 15.2 m; small, healthy, lemon yellow), CHPd131 (14:38, 10.9 m; a healthy adult with a bleached base), CHPd132 (14:43, 8.9 m; healthy, among many 100% bleached Seriatopora), CHPd133 (14:49, 11.8 m; 100% bleached), and CHPd134 (14:59, 5.7 m; very pale, partly dead). Anderson also sampled four Seriatopora hystrix colonies: ChSe138 (14:15, 14.5 m; a 100% bleached recruit on dead rubble), ChSe139 (14:20, 16.0 m; 100% bleached, in a crack in the rock), ChSe140 (14:23, 15.0 m; 100% bleached, half smothered by macroalgae, no live tissue evident), and ChSe141 (14:54, 10.4 m; green fluorescent, likely 100% bleached, no live tissue evident; no healthy seriatoporids were seen at the site). 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).

Other notes

Aspect follows Anderson's field sheet (LOF fellowship 2016 workbook: 'lagoonal patch reef', 'leeward'); the expedition's 933-site table classes the station as 'protected' (patch reef). Esri World Imagery (no LOF habitat map covers Salomon atoll; the LOF Chagos habitat map covers only Peros Banhos) puts the pin among patch reefs in the south-west part of the Salomon lagoon, consistent with the sheet.