N. GBR - Green (AULK21)

Setting

This is a no-take Green Zone.

General benthic features

Thirty-four frames from this Green Zone dive split into three stories. The first is the low-cover matrix the survey figure describes: repeated wide frames of broad, low-relief pavement and dead branch rubble under a rust-and-olive turf film, running off into blue with only isolated heads breaking the plane (e.g., Image 12, Image 24, Image 15, Image 18, Image 13), and large aprons of clean carbonate sand between bommies (e.g., Image 2, Image 4, Image 6, Image 1).

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Where heads did break the plane, they carried lobed lilac-gray massive and plating colonies with small pink-brown Pocillopora tucked among them, over turf-covered pavement (e.g., Image 14).

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The second is that the coral that is present is patchy but locally good: a shallow crest under a rippled surface carrying a genuinely mixed assemblage of tabulate and corymbose acroporids, encrusting and foliose colonies, and pink coralline rock (e.g., Image 34, Image 32, Image 33, Image 31); a mound of stacked knobby massives with soft corals between them (e.g., Image 10); a large meandroid brain colony filling one frame (e.g., Image 23); a green, fine-pored massive dome pressed against a lilac-gray plating colony (e.g., Image 11); healthy pink-brown Pocillopora and corymbose Acropora clusters (e.g., Image 21, Image 25); staghorn thickets, one of them growing straight out of a mat of dark red macroalgae with standing dead branches behind it (e.g., Image 26, Image 22, Image 9); and the cream reticulated Porites rus branches with a violet finger colony beside them (e.g., Image 20).

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Coral cover

• Reference: Khaled bin Sultan Living Oceans Foundation, Global Reef Expedition (in situ transect)
• Coral cover 19%, from the LOF-GRE in situ point-count transects (Global Reef Expedition site data, 933 sites).
• Transect mean 19 ± 2.3% SE (n = 4 transects; Living Oceans Foundation per-transect benthic data); the headline above is the expedition's station value.

Stressors

The third story is bleaching: several colonies are stark white with polyp structure still intact and no algal film. A knobby massive head is tan over its upper two-thirds and bone-white across the lower third (e.g., Image 8); a meter-wide digitate Acropora is divided almost down the middle, tan on one side and white on the other (e.g., Image 27); and two cauliflower-form Pocillopora colonies are white throughout, one of them sitting directly beside an evenly pigmented tan Porites that shows the contrast plainly (e.g., Image 28, Image 3).

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That is a description of the frames, not a bleaching estimate, and the set is far too small a sample to say how widespread it was. Crown-of-thorns starfish appear in three separate frames, one of them sprawled over a patch of freshly bared white skeleton (e.g., Image 29, Image 30, Image 7).

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One large branching colony stood entirely dead, every branch furred in maroon turf, with no starfish in view (e.g., Image 19).

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The 2014 dive notes also record crown-of-thorns starfish here: one seen by the note-taker and several more by another diver (Anderson's GBR field notes, 2014).

Fish and other fauna

Fish life is conspicuous: big dark sweetlips loafing over the sand (e.g., Image 2, Image 6, Image 1) and barracuda hanging in the blue above it (e.g., Image 4, Image 5).

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Comparisons with other data

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

Other notes

Two frames are method shots of a diver holding a large square survey frame in open water (e.g., Image 16, Image 17).

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The field report's station table lists this position under AUR518; its rows for 5-6 September 2014 are shifted by two stations, and the 933-site table and Anderson's notes place AUR518 on Ribbon Reef 5.