Triton Bay - Bo Rainbow

Setting

This is a broad, gently sloping reef terrace rather than a wall or a pinnacle — the frames repeatedly look out across a wide, low-relief plain of coral and soft coral, with a shallow crest visible up-slope in some frames and one steeper coral-covered flank falling into blue in others. Water is noticeably greener and more particle-laden than at the Dampier Strait sites in this group; visibility is moderate rather than excellent, the far field goes soft green-gray within a modest distance, and there is visible suspended material in several frames.

General benthic features

What makes this site distinctive is that OCTOCORALS, not stony corals, dominate large parts of the bottom (e.g., Image 2).

2

Multiple frames show near-monospecific meadows of a tan-to-rust branching soft coral (the fine, limp, repeatedly-forking Sinularia flexibilis / Litophyton growth form) carpeting the substrate from foreground to horizon, tens of meters across, with only occasional hard coral colonies emerging through them (e.g., Image 4, Image 5).

45

Elsewhere there are dense fields of cream and olive leathery soft corals in folded-cabbage, mushroom, and lobed forms consistent with Sarcophyton and Lobophytum — one frame is nothing but overlapping leather colonies — plus finger and cauliflower leathers consistent with Sinularia. On the steeper, shaded flank the character changes completely into a classic Indo-Pacific soft-coral wall: vivid red, crimson, pink, and salmon Dendronephthya-type tree corals with translucent inflated trunks, one large deep-purple/magenta Dendronephthya clump on open sand, orange and apricot colonies, all interspersed with black-coral bushes (Antipathes-type, pale gray-white feathery trees, several of them large) and fine wire/whip corals. Stony corals are still abundant where the octocorals thin out: dense staghorn and bottlebrush Acropora thickets in tan, mauve, and pale blue-gray, low tabulate, and corymbose plates, big brown digitate colonies, columnar and knobbly branching colonies, large brown foliose plates in overlapping laminae, a big gray-blue meandroid brain colony sitting on open sand with sharply worm-track valleys (Platygyra-type), several massive Porites-form domes, small bushy Pocillopora- and Seriatopora-type heads, yellow-green Turbinaria-like laminae, encrusting sheets, and a solitary polyp with long white-tipped tentacles on sand consistent with Heliofungia actiniformis or a Euphyllia. Anemones are a repeated feature — at least three separate large host anemones, including a gray-brown carpet anemone with tightly curled tentacles (Stichodactyla-type) and a green-tentacled anemone with orange-and-white anemonefish visible at its edge. Other benthos: extensive pink and mauve crustose coralline algae, a lot of it on open dead pavement between colonies; fine turf; dark red and brown fleshy macroalgal tufts; encrusting red, orange, and yellow sponges; scattered purple-and-yellow ascidians; a small pale-blue solitary ascidian; a striking white feather-duster/tube worm crown; abundant crinoids in yellow, cream, black, and banded forms; and a spectacular aggregation of bright-yellow spiky sea cucumbers (the Colochirus robustus look) clustered on sand at the base of a branching colony — the frame Anderson himself filed as "sea cucumber orgy" (e.g., Image 6).

6

Coral cover

Coral cover: 13% — a blind Claude computer-vision point count of 47 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

Health: no crown-of-thorns, no disease lesions, no anchor or blast damage, and no widespread bleaching. Two things are worth noting rather than assuming. First, at least two small colonies read as chalk-white against pigmented neighbors (a small pale-blue-and-white branching colony sitting alone in a clearing in the soft-coral meadow, and a white branching colony beside tan acroporids), the same signal flagged at Mioskon and Blue Magic — but here it is isolated and minor, and each of these could also be a naturally pale colony or a partial mortality scar. Second, large tracts of open, coralline-crusted pavement and sand run through the site between the octocoral meadows; that is habitat structure, not necessarily damage (e.g., Image 8).

8

Fish and other fauna

Fish are present but subordinate to the invertebrates here: chromis and other planktivorous damselfishes over the coral, wrasses including a yellow-headed and a blue-green individual, a small yellow angelfish or butterflyfish, an anemonefish, scattered anthias, and small fish schooling loosely over the crest — no big pelagic aggregation of the kind seen at Blue Magic.

Comparisons with other data

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

Dive record

Bo Rainbow, dived 15 October on Anderson's 2018 Indonesian liveaboard trip.

Other notes

Man-made content: divers appear in about eight frames, including one with a large camera-and-strobe housing on a tray, one with a yellow single-blade fin, and one with distinctive salmon-pink fins.