Chagos Archipelago - Salomons Island (BISA105)

Setting

BISA105 is a lagoonal patch reef in the Salomon lagoon, leeward on Anderson's field sheet, dived 29 April 2015 to 29.3 m; its characteristic architecture is a sequence of coral-capped blocks and pinnacles separated by narrow sediment pockets. Water clarity changes appreciably across the sequence. Suspended material softens contrast in the first several frames, and some surfaces appear muted or gray from distance and backscatter; later images use closer illumination and stronger color balance. No quantitative turbidity value is supported by the photographs and none is reported.

General benthic features

Lobophyllia and Porites lead at 12% of the benthos each, followed by Goniopora at 8.1%, and the three together account for 62% of all coral recorded. Pavona follows at 5.6%, Acropora only fifth at 3.5%, then Favia 2.3% and Goniastrea 1.1%. A ten-genus tail below 0.5% includes Favites, Ctenactis, Physogyra, Astreopora, Turbinaria, Alveopora, Galaxea, Montastrea, Montipora, and Platygyra. Bare substrate holds 12% of the benthos, non-coral invertebrates 11%, macroalgae 10%, turf 7.6%, and crustose coralline algae 7.5%. The depth structure is a clean handover between the three lead genera. D2 carries 55% coral and is the Lobophyllia band — 17%, with Pavona 9.8% and Goniopora 5.8% — and is also the richest at 19 genera. D3 holds 54% and inverts to Goniopora at 21% with Porites 14% and Lobophyllia 9.5%, on the site's lowest algal cover of 10%. D4 falls to 42% and becomes a Porites reef outright at 27%, with algal cover rising sharply to 47% and richness dropping to eight genera. The site-level 12% Porites figure is therefore the average of a band where it is absent from the top three and one where it holds better than a quarter of the benthos. Two frames show plates projecting from older framework and massive colonies stacked above one another (e.g., Image 2).

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Two more frames show convoluted surfaces with deep crevices providing shelter and shaded microhabitat (e.g., Image 1, Image 17).

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A pinnacle rises into clear blue water, capped by massive heads, with branching colonies along its exposed edges (e.g., Image 3).

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The prominence of massive, lobate, and mound-forming colonies in these frames is the photographic counterpart to a Porites–Lobophyllia–Goniopora assemblage. Non-coral color and texture are conspicuous. Bright magenta, red, and orange encrusting patches occur on vertical faces and shaded recesses, and brown foliose or blade-like growth appears around a pale branching colony in one frame (e.g., Image 25).

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These are described morphologically because a still photograph cannot securely separate sponge, coralline algae, and other encrusting taxa in every case, but they demonstrate that shaded and exposed microhabitats differ strongly across the outcrop. The photographs document rugged pinnacles, stacked massive and plating colonies, narrow sediment pockets, and colorful encrusted framework under variable visibility, plus white colonies on the shallow pinnacles.

Coral cover

• Reference: Mayfield & Dempsey (2026)
• CoralNet submission package
• BISA105 is a lagoonal patch reef with 52% transect coral cover and 24 non-zero coral genera (LOF transects, 2015), and it is emphatically not an Acropora reef.
• Transect mean 52 ± 7.0% SE (n = 8 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 50% (Mayfield & Dempsey 2026, Oceans, suppl. S1).
• Formal surveys give 52% coral, 26% algae, and 11% non-coral invertebrates, the coral led by Porites, Lobophyllia, and Goniopora in a depth-dependent order.

Stressors

Because clarity and lighting change across the frames, condition calls are based on coherent tissue pallor across intact colonies rather than isolated bright patches. In the photographs, white massive, plating, and branching colonies show in at least eight of the 25 frames, mostly on the shallow pinnacles, as Anderson's dive notes describe (e.g., Image 13, Image 21, Image 25).

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One frame shows a branching colony tucked beneath a ledge whose tissue is nearly uniformly white, fine branchlets intact, contrasting with surrounding brown macroalgae and pigmented encrusting surfaces. On another pinnacle, bright, pale branching colonies stand out sharply against the neighboring brown and tan massive corals (e.g., Image 13); pale branches recur elsewhere on the reef (e.g., Image 21). Other pale surfaces were deliberately excluded: strobe reflection brightens smooth massive colonies, and exposed skeletal patches and naturally pale growth tips can mimic bleaching. The published site figure of 5.6% contrasts with Anderson's dive notes, which describe most of the corals on the high-cover 10–20 m reef as bleached or bleaching, though no bleaching was seen at 25–30 m. Anderson's sampling sheet records 11 colonies sampled here at 3.7–28.0 m: five Pocillopora damicornis and three P. acuta by RFLP; three Seriatopora hystrix by field call; the condition notes run from healthy to 100% bleached, with some partly dead colonies. 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 no cyanobacteria and no recently dead coral.

Fish and other fauna

Small planktivorous fishes occur against blue water above the pinnacle (e.g., Image 3) and darker reef fishes move among the crevices in earlier views; the frames are not standardized for fish abundance and no individual can be assumed unique across adjacent photographs.

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, eight independent stations recorded station-year means of 6.8–63% hard coral cover between 2006 and 2020; the nearest, Sheppard et al. (2008) at Salomon, 1.78 km away, read a mean of 32% in 2006.

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 on a small patch reef in the Salomon lagoon, consistent with the sheet.