Atauro - Compass Reef snorkel

General benthic features

The South frames show a shallow garden of remarkable density. One is filled by a single large pale blue-gray corymbose Acropora colony, its plates interlocking above dark shadowed voids, with olive-green branching colonies, small gray lobate Porites, and a honeycomb faviid crowding in from the edges and green algal tufts in the gaps (e.g., Image 1).

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A second is a wide view over big salmon-pink corymbose Pocillopora-like domes, mauve-pink plating colonies, a tan maze-patterned brain coral, gray-lavender lobate Porites heads, a pale yellow-green foliose colony, and background thickets of tabulate and staghorn Acropora, with a bright teal parrotfish and several damselfishes passing through (e.g., Image 2).

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A third is the densest frame of the set: orange-brown, pink-mauve, and cream corymbose colonies, purple encrusting plates, fine branching thickets, mushroom corals, and knobby pale Porites packed edge to edge with almost no bare substrate — and one distinctly pale gray-white branching colony among pigmented neighbors, which from a photograph alone cannot be separated into pale pigment, bleaching, or recent mortality (e.g., Image 3).

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The fourth South frame is the counterpoint: a coarse coral-shell sand plain with red and orange encrusting sponges on scattered rubble, no live coral, and a dark knobbed sea star with blue tubercles (a Protoreaster-type) crossing it (e.g., Image 4).

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The house-reef frames are shallower and flatter. One is again a dense, high-diversity garden — cream domes of massive Porites, a textured Hydnophora-like mound with sinuous white ridges, a small pale table Acropora, pink corymbose colonies, pale honeycomb faviids, and dark plating colonies (e.g., Image 7).

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The other three show the flat's real character: small massive, lobate, and cerioid colonies scattered across pale sediment-veneered pavement and rubble, with green algal turf, branching coralline tufts, small pale Acropora colonies, and genuine seagrass shoots on the sand between them (e.g., Image 6, Image 8).

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Different growth forms are tightly interleaved in many frames, producing strong fine-scale structural complexity (e.g., Image 5).

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Living cover here is patchy and massive-dominated rather than continuous.

Coral cover

• Reference: Claude CV point count (this site's photos)
• Coral cover: 38% — a blind Claude computer-vision point count of 99 of Anderson's edited photographs (20 points per photo; water, fish, and obstructions excluded). Other computer-vision methods are listed in the method table.

Stressors

One low knobby colony had a stark cream-white center with its knobs intact, grading to pigmented gray-green and lavender-pink margins: a partly bleached colony (31 January snorkel) (e.g., Image 21).

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Two neighboring massive colonies have pale cream crowns above normally pigmented brown sides, while a brain-form colony beside them is evenly pigmented: partial paling (bleaching) of their upper surfaces (31 January snorkel) (e.g., Image 22).

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No uniform, reef-wide bleaching signal is apparent. No crown-of-thorns starfish (COTS) or other corallivores were evident.

Fish and other fauna

Sea stars are conspicuous mobile invertebrates, including a black species with blue-tipped tubercles and an orange-and-black knobbed individual (photo not shown), and a bright-blue five-armed Linckia-type sea star on a massive colony (photo not shown).

Comparisons with other data

The XL Catlin Seaview Survey covered a nearby station (transect 30015) in 2014, 0.46 km from the pin; we could not confirm that it is the same reef. Within 5 km, eleven independent stations recorded station-year means of 17–65% hard coral cover between 2004 and 2017; the nearest, Reef Check at Rai keta tungu, 0.42 km away, read 65% in 2017.

Dive record

Snorkeled twice, on 31 January and 1 February 2024, in about 2 m of water — and the first eight photographs come from two spots, four frames at Compass Reef South and four on the Compass house reef.