N. GBR - Pink (AUR611)

Setting

Anderson's notes call this leeward coral pinnacle on Ribbon Reef No. 6 "beautiful" and "interesting", and the photographs make clear why — and also that the site has two very different halves. This Preservation Zone site carries the Marine Park's tightest protection, with entry itself restricted.

General benthic features

Eight frames (e.g., Image 26, Image 27, Image 28, Image 29, Image 30, Image 31, Image 32, Image 21) are shot across the top of the pinnacle in bright blue water and show a near-continuous branching-coral pavement running to the limit of visibility.

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Antler- and staghorn-form Acropora dominate in rust-orange, tan, cream, and blue-gray, growing shoulder to shoulder with almost no bare substrate between colonies (e.g., Image 27, Image 28, Image 30, Image 31); blue-tipped digitate colonies are mixed through the orange thickets (e.g., Image 26, Image 28, Image 31), and stacked pale tables sit on the crest behind them (e.g., Image 27, Image 31). Two frames are given to single large tabulate Acropora plates, one roughly a meter and a half across with a clean growing rim and a shaded undercut (e.g., Image 24, Image 32).

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A separate frame is a carpet of pink-mauve corymbose Acropora and Pocillopora piled over one another (e.g., Image 21). A second group of frames turns down and off the pinnacle, and the character changes completely: hazier green-tinged water, mound-and-groove rock with low knobby olive-green massives and scattered small colonies (e.g., Image 7, Image 16, Image 20), sponge- and encrusting-covered rock walls dropping into blue (e.g., Image 19), and rubble-and-sand floor with isolated colonies — among them a large dark foliose colony standing alone on coarse sand (e.g., Image 2).

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A last close-up shows a salmon-pink knobby encrusting colony with pale patches (e.g., Image 33).

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Coral cover

• Reference: Khaled bin Sultan Living Oceans Foundation, Global Reef Expedition (in situ transect)
• Anderson's notes put coral cover at 100% over most of the 2-3 m crown and under 5% at 20 m, where rubble prevailed; these frames are the visual counterpart of the 37% site mean: the crown and the flank are not the same reef, and any single frame from this set will misrepresent the other half.
• Transect mean 36 ± 3.1% SE (n = 4 transects; Living Oceans Foundation per-transect benthic data); the headline above is the expedition's station value (the headline weights each depth equally; two depths had a single transect).
• What the frames cannot settle: none of these are planar downward views, so no cover figure can be taken from them; the split between crown and flank means frame-level impressions are strongly position-dependent.

Stressors

Five close-range frames are devoted to pale and stark-white branching colonies with polyps extended and a slack, mucus-like sheen on the tissue (e.g., Image 3, Image 5, Image 8, Image 9, Image 10).

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Image 8 is the clearest: a completely white branching colony ringed by scarlet and pink encrusting sponge and coralline. Image 5 shows a tan colony with a white branch group, and Image 4 shows a bright white branching colony on the reef top among darker rubble.

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Anderson's field note for this site records that some Pocillopora colonies were mostly bleached and covered in mucus; the mucus, he noted, looked to be of exogenous, rather than endogenous, origin ("Very strange"), and the photographs are consistent with that. Two of the close-ups are soft-focus at that working distance (e.g., Image 9, Image 10), and the affected colonies cannot be identified to genus from the imagery. No count or extent is given here: these are targeted close-ups of the colonies that caught his eye, not a survey of how much of the reef looked like this, and the wide crown frames show no obviously bleached colonies at all. No crown-of-thorns starfish (COTS) or other corallivores evident.

Fish and other fauna

Fish are heavy over this half: clouds of chromis and small planktivores in nearly every crown frame, dense fusilier schools filling the water column (e.g., Image 17, Image 22, Image 12), and a tight shoal of sergeant-major-type damselfish over the reef top (e.g., Image 13).

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The remaining frames record the fauna. Two gray reef sharks cruise over the reef in open blue water in the opening frame (e.g., Image 1), and a slender banded shark — his "cat shark" — lies tucked under a coralline-crusted ledge (e.g., Image 23).

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Two frames are close-ups of a single large gastropod shell on the rubble floor, one of the whole animal and one of its glossy cream aperture (e.g., Image 14, Image 15).

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His notes also record a huge Alveopora colony, a large grouper (about 1 m), and a gray reef shark approaching 2.5 m.

Comparisons with other data

No other surveys have been conducted at this site to date. Within 5 km, two AIMS manta tow stations recorded 11–36% hard coral cover between 1994 and 2021; the nearest, AIMS manta tow at RIBBON NO 6 REEF, 0.86 km away, read 11–35% between 1994 and 2017.

Other notes

Two frames contain a diver (e.g., Image 6, Image 18), and Image 12 is almost entirely green midwater with fish and heavy backscatter.

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A pale angular object intrudes at the left edge of one crown frame (e.g., Image 25) and may be survey gear rather than reef.

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Depth is not resolvable from the imagery.