Indonesia - Halmahera: Mugia

General benthic features

The reef itself, in the two frames that show it wide, is a bed of stacked, upward-cupped foliose plates — tiered shelving plate after plate to the edge of the light, consistent with Turbinaria and foliose Montipora-type corals — and it is genuinely extensive, matching the "amazing coral cover" in Anderson's field note (e.g., Image 3).

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The one close reef frame is the most informative on composition: dense fine-branched yellow-green thickets consistent with Seriatopora and Acropora, cream knobby branches consistent with Pocillopora, gray-green digitate colonies with polyps fully expanded, and foliose plates packed together with almost no bare substrate between them (e.g., Image 1).

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The macro frame is a tan-gold branching colony with its polyps out, consistent with a branching Porites, growing over pink crustose coralline algae with a red-orange encrusting sponge alongside it (e.g., Image 2).

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Coral cover

Coral cover has not been estimated for this site. Mugia was a night dive shot as macro rather than reef-scale frames, so no computer vision figure applies and none is published.

Stressors

The condition finding at this site is crown-of-thorns. Two frames show a large Acanthaster-type crown-of-thorns starfish — on the order of 30 cm across, pale blue-gray disc, orange-tipped spines, out, and active in the open as they are at night — and the substrate immediately around it in both frames is turf-covered dead branching rubble rather than living thicket, with only a laminar gray-brown plate consistent with Pachyseris and a few live branches surviving at the frame edges (e.g., Image 5, Image 9).

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The two frames may be one animal photographed twice; nothing in them settles that. No feeding scar was caught on a living colony in these six frames, so this is recorded as a crown-of-thorns presence with associated dead substrate, not as documented active predation. No bleaching and no disease were seen, with the color caveat above standing.

Fish and other fauna

Fauna: a green turtle, consistent with Chelonia mydas, resting on the foliose plate bed across two frames (e.g., Image 4).

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Anderson's field note adds a whitetip reef shark and a huge cuttlefish, and records that he hunted for walking sharks here without luck — he had found them in numbers three nights earlier at Pantai Falajawa.

Comparisons with other data

No prior survey data from this site. If you would like to share yours, please email us.

Dive record

Mugia was a night dive on 13 August 2026, the fourth and last dive of that day on the August 2026 Halmahera crossing aboard the liveaboard Ambai (Wallacea Dive Cruises), to a maximum of 17.6 m in 24-25°C water — the cold end of the trip, on the same day and in the same water body as Jerot, where Anderson logged 22-25°C and weird thermoclines and wondered in his log whether this is an upwelling area.

Other notes

Only six still frames survive the dive, plus one movie clip and a raw folder, and all six were reviewed. Every one is a flash exposure against a black background, which is the folder evidence that settles the dive as nocturnal, and it also means no site cover figure is published here and that color cannot be used to score bleaching: nocturnal flash whitens branch tips and washes out pigment, and coral polyps are expanded, both of which imitate pallor. Anderson's field note: “turtle, white tip, huge cuttlefish, hunted for walking sharks but no luck, amazing coral cover”