Indonesia - Halmahera: Batu Balong shallows-near anchorage

Setting

Batu Balong shallows, near the anchorage (Halmahera dive 22), was a short solo dive on 14 August 2026 during the Halmahera crossing aboard the liveaboard Ambai (Wallacea Dive Cruises): in at 12:53 for 32 minutes, to a maximum depth of 5.9 m, in water of 26–27°C. It followed the main Batu Balong dive, and Anderson went on his own to explore the hard corals of the 1–6 m shallows beside the anchorage.

General benthic features

The signature habitat, and the reason for the dive, is branching Acropora thicket at 1–4 m: mauve, lavender, tan, and olive staghorn stands consistent with Acropora formosa/muricata, interlocking across whole frames with almost no substrate visible between branches (e.g., Image 2, Image 3, Image 6, Image 17, Image 36, Image 37).

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Around them the crest is a mixed shallow community — corymbose and digitate Acropora, fine-branched colonies consistent with Seriatopora and Stylophora, and Pocillopora-type heads packed over old framework — with large smooth and knobbed Porites bommies and columns, several meters across, often with encrusting Montipora running over their flanks (e.g., Image 8, Image 10, Image 12, Image 26, Image 38).

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Where the reef top rolls over, tiered foliose plates consistent with Montipora, Echinopora, and Turbinaria form stacked brown and violet terraces, and meandering-valley brain corals consistent with Platygyra or Leptoria, with Goniastrea- and Favites-type heads, are scattered through the massive ground (e.g., Image 4, Image 15, Image 23, Image 25, Image 49).

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White sand lanes floored with rubble run between the coral ridges, lined with leathery Sarcophyton- and Lobophytum-type soft corals and brown pulsing xeniids; a minority of frames show old rubble and turfed framework under pink coralline crust, with foliose corals recolonizing it (e.g., Image 5, Image 11, Image 34, Image 35).

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Coral cover

Coral cover: 57% — a blind Claude computer-vision point count of 213 of Anderson's unedited photographs (20 points per photo; water, fish, and obstructions excluded). Other computer-vision methods are listed in the method table.

Stressors

No bleaching was evident: the pale and white branch tips through the Acropora thickets are actively growing tissue, and the colonies behind them are fully pigmented (e.g., Image 48, Image 53).

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No diagnosable disease, fresh mortality, crown-of-thorns starfish, or predation scars were seen in the frames reviewed; where dead ground occurs it is old, consolidated rubble and framework under turf and coralline algae, already being overgrown. For a reef at 1–6 m, exposed to the most light and the most wave energy, this is a notably intact shallow coral community.

Fish and other fauna

Clouds of blue-green damselfish consistent with Chromis viridis hovered over the Acropora thickets and dropped into them when approached, and anthias, other damselfishes, small wrasses, butterflyfishes, and a surgeonfish were recorded over the crest.

Comparisons with other data

No independent survey was made at this exact site; the nearest ones are listed in the table below.

Other notes

Anderson's field note: “went on my own to explore the spectacular hard corals of the shallows (1-6 m, near anchorage)” (e.g., Image 2, Image 6, Image 10, Image 17, Image 31, Image 36)

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