Indonesia - Halmahera: Sali Bay-Batu Mangga

Setting

Sali Bay-Batu Mangga was dived twice on 11 August 2026. The first dive (07:53, Halmahera dive 9) was a strong-current reef-hook drift, and the imagery shows it: a stretch of near-black, near-zero-cover frames reads as a deep, dim, current-swept passage rather than a data gap (e.g., Image 37, Image 40, Image 48).

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The second dive (11:27, Halmahera dive 10) reached 29.1 m at 25–26°C. Anderson's field note is about the water rather than the reef: "sites have been generally low visibility due to suspended sediments, might be helping cool off corals" — a personal hypothesis, not a measurement, and the photographs certainly bear out the first half of it. Nearly every wide frame is hazy, with a milky green-blue cast and heavy backscatter beyond three or four meters (e.g., Image 65, Image 92, Image 97, Image 106, Image 108).

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General benthic features

On the first dive, cover is genuinely patchy and colorful. Standout set-pieces include a vivid red brain coral sitting alone on white sand, clusters of pink tube/barrel sponges, and a striking purple-red-yellow soft coral/sponge assemblage on the wall followed later by a magenta gorgonian-and-soft-coral bouquet and orange soft coral fields (e.g., Image 16, Image 21, Image 31, Image 53).

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Extensive pale corymbose and staghorn Acropora thickets, mostly cream to pale gray-brown with normal white growth tips, dominate the mid-dive stretch and account for several of the highest single-frame readings (e.g., Image 3, Image 6, Image 9, Image 11, Image 20, Image 24, Image 27, Image 33, Image 42).

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Large ruffled foliose plate corals recur, and a big smooth green-brown massive colony with a hard, glossy surface appears mid-dive (e.g., Image 7, Image 12, Image 23, Image 26, Image 36, Image 45).

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On the second dive, the site is a filter-feeder wall first and a coral reef second (e.g., Image 64, Image 75, Image 87, Image 109).

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The slope and its overhangs are upholstered in sponges of every form and color — maroon, crimson, ochre, violet, mustard-yellow, and pale green encrusting sheets, red barrel sponges, tan and pink tube clusters — interleaved with purple and lilac gorgonian fans, jet-black bushy antipatharian colonies, cream and orange arborescent soft corals, colonial ascidians, and yellow, orange, and white feather stars, all under a permanent red curtain of anthias (e.g., Image 67, Image 70, Image 74, Image 85, Image 93, Image 96, Image 102).

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Hard coral on this stretch is mostly broad foliose and laminar plates: meter-scale brown and olive whorled plates consistent with Turbinaria, Montipora, and Pachyseris, some laid out flat across the pavement in overlapping sheets, plus massive Porites and Diploastrea domes, a scarlet meandroid brain coral, and large gray-lavender tabulate Acropora (e.g., Image 57, Image 58, Image 61, Image 63, Image 68, Image 71, Image 72, Image 73, Image 77, Image 78, Image 79, Image 80, Image 81, Image 83, Image 94, Image 98, Image 101, Image 103, Image 104).

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A rubble-and-sand pavement between bommies gives the low-cover frames, and the deepest, haziest frames are near-empty blue water over distant reef (e.g., Image 76, Image 95).

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The shallow terrace is a different reef again: a broad, near-continuous field of tan and rose-brown staghorn Acropora with white growth tips, running to the limit of visibility under a dense cloud of damselfish (e.g., Image 84, Image 90, Image 110).

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Coral cover

• Reference: Claude CV point count (this site's photos)
• Coral cover: 25% — a blind Claude computer-vision point count of 361 of Anderson's unedited photographs from this site's two dives on 11 August 2026, given as the mean of the dive means (29% from 125 photos at 07:53, 21% from 236 photos at 11:27; 24% pooled over all 361 photos; 20 points per photo; water, fish, and obstructions excluded). Other computer-vision methods are listed in the method table.

Stressors

On the 07:53 dive, the photo review of 127 frames saw no bleaching, disease, crown-of-thorns, or predation, and read the pale coloration on the staghorn fields as a normal growth-tip morph, not tissue loss; across both dives, however, a computer-vision point count called 0.6% of coral points bleached (7 of 361 photos). On the same dive, a plating coral over a red sponge carries stark-white patches, recent mortality, cause not stated (e.g., Image 46).

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On the 11:27 dive, no bleaching was confirmed. One large tabulate Acropora reads distinctly whiter than its neighbors, pale bluish-white with no brown pigment, in a frame where the surrounding anthias are fully colored — but naturally pale gray-lavender table morphs are common here (a second, normally pigmented table in another frame is only a little darker), so this is logged as unresolved rather than as bleaching. On the same dive, one brown plating colony carries a sharp-edged, stark-white bare patch in the middle of the plate, with no tissue or turf on the skeleton: recently dead, and the cause is not known (e.g., Image 56).

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No crown-of-thorns, no Drupella aggregations, and no active disease lesions were recorded. Some plate margins carry small pale patches already being colonized by crustose coralline algae — healed minor injury, not an advancing front.

Fish and other fauna

Anderson logged sharks and a turtle on the 07:53 dive; neither appears in the published photographs. Fish life is heavy throughout the second half — dense damsel and anthias clouds hang over the branching fields. A dense swarm of black-and-white striped eel-like fish, consistent with juvenile striped catfish or convict blennies, covered whole sections of the reef in two frames; a huge scarlet Dendronephthya soft coral stood over the slope; anemonefish in a bubble-tip anemone; anthias, fusiliers, damselfish, silversides, wrasse, and butterflyfish throughout (e.g., Image 59, Image 60, Image 66, Image 99).

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Comparisons with other data

We found no other surveys at this site as of 2026. If you would like to share yours, please email us.

Other notes

Anderson's field note: “strong current dive (used reef hook), sharks, turtle, adventure”