Indonesia - Banda Islands: Lava Flow (Gunung Api)

Setting

Lava Flow sits under Gunung Api on the 1988 flow and was dived on 25 April 2018 from 12:40 to 13:45, 65 minutes to a maximum of 13.7 m and an average of 7.62 m at 29.44°C.

General benthic features

The habitat zones. The staghorn and corymbose Acropora thicket slope is the dive, 70 of 192 frames: unbroken carpets running out of sight into blue water, in brown, olive, and lilac color morphs, with tabulate tables set through them (e.g., Image 1, Image 2, Image 15, Image 22, Image 23, Image 24, Image 25).

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A foliose plate garden (30 frames) of Turbinaria, foliose Montipora, and Pachyseris fills the gullies, including the lava channel the site is named for, which now carries essentially complete plate-coral cover (e.g., Image 3, Image 9, Image 10, Image 13, Image 14).

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A genus-rich pavement and drop-off mosaic (59 frames) adds massive and columnar Porites, Pocillopora, Seriatopora, Stylophora, Goniopora-type colonies with extended polyps, meandroid Platygyra/Leptoria brains, and fungiids, with blue, and yellow colonial ascidians, black coral bushes, crinoids, and encrusting sponges through it — 20-plus hard coral genera (e.g., Image 6, Image 16, Image 17, Image 18, Image 19, Image 20, Image 21).

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A soft-coral garden of bushy Sinularia/Litophyton-type colonies (6 frames), the shallow crest (7), cryptic overhangs (5), and bare basalt shallows (4) complete it. That basalt is angular, unbroken bedrock and boulder with crustose coralline and sparse small recruits — young lava, not dead reef, and deliberately distinguished from the mortality ground.

Coral cover

Coral cover: 55% — a blind Claude computer-vision point count of 190 of Anderson's edited photographs (20 points per photo; water, fish, and obstructions excluded). Other computer-vision methods are listed in the method table. Anderson is still comparing computer-vision models, and these figures will be updated as the methods improve.

Stressors

Condition. Eleven frames are primary recent-mortality ground: broad fields of disarticulated Acropora branch rubble and standing dead staghorn still in growth position under algal turf, with damselfish over it (e.g., Image 11).

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Eighteen frames carry stark-white colonies among pigmented neighbors — low-level, colony-scale bleaching in Acropora, Pocillopora acuta-type, Seriatopora, and massive Porites, not a reef-wide event. One plating colony carries unambiguous white parrotfish bite scars. No Acanthaster and no Drupella appear in any frame. The cause is not asserted: dead staghorn under turf, branch rubble, and a minority of freshly bleached colonies are consistent with recent thermal stress, physical breakage, or both, and the photographs cannot separate them.

Comparisons with other data

Roughly half the frames show living coral covering the great majority of the benthos, so the photographs sit far closer to the 2016 figure than the 2019 one; if the two reefs tracked each other at all, most of that loss came in the twelve months after this dive (e.g., Image 4, Image 5, Image 8, Image 12).

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They need not have tracked each other, and a separate Reef Check station actually named Lava Flow, 1.94 km off, held 63–76% hard coral across 2015–2019 with no collapse at all. Different station, different observers: a near-concurrent cross-check, not a repeat of this site.

Dive record

It is the second dive of the trip and, on the photographs, the highest-cover site of the six reviewed here.