N. GBR - Green (AUYG37)

Setting

Structure reads clearly in the wide frames. Several look along or down a convex crest that falls away steeply into deep blue (e.g., Image 6, Image 10, Image 14, Image 25, Image 26, Image 30), with the shallow band carrying the densest coral and the visible slope thinning as it drops.

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Two more frames run straight down the slope face, an unbroken mosaic of small colonies falling away into deep blue, one with a diver for scale (e.g., Image 5, Image 9).

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Frames looking upward (Image 7) show surface light and open water above the drop.

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The expedition surveyed Yonge Reef as one of its Green (no-take) reefs; under the GBRMPA Zoning Plan the reef is a Scientific Research Zone (no-take, research by permit) with a Conservation Park Zone on its lee side, and the recorded position lies inside the Scientific Research Zone.

General benthic features

Thirty-three frames from Yonge Reef make the point: this is a shallow, high-energy reef whose coral is built from very many small colonies rather than a few big ones, and the photographs show that texture over and over. The downward and oblique frames (e.g., Image 4, Image 8, Image 13, Image 15, Image 16, Image 17, Image 20, Image 23, Image 24, Image 26, Image 27, Image 29, Image 31) are a dense confetti of corymbose and digitate Acropora, small Pocillopora, low massive faviids, encrusting Montipora-type sheets in blue, green, and rust, and scattered small tables, all set into pink and lilac crustose-coralline pavement with rubble in the interstices.

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Image 27 is the densest single frame — a run of tan and orange knobby and digitate colonies with a deep maroon-pink colony at its center — and Image 8 and Image 17 the most instructive, showing how much of the surface between colonies is coralline crust and turf rather than living coral. There is no single dominant growth form: branching, digitate, corymbose, encrusting, and small massive colonies are all present in most frames, along with occasional broader plates (e.g., Image 8, Image 14, Image 19), and the tall finger-like colonies in Image 13 and Image 27 stand out against an otherwise low-relief surface.

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On the upper slope, pink, lilac, and cream knobby colonies crowd shoulder to shoulder, with a small pink plate colony among them (e.g., Image 12), and one frame centers on a large tan colony of thick, flattened upright lobes surrounded by smaller branching and massive colonies (e.g., Image 18).

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Montiporids and Stylophora held their own at mid-depths, and a patch of Sinularia and stinging hydroids carpeted parts of the reef.

Coral cover

• Reference: Khaled bin Sultan Living Oceans Foundation, Global Reef Expedition (in situ transect)
• The transect counts what lies under each survey point, coralline crust and turf included, not any judgment of the frames.
• Coral cover 24%, from LOF-GRE in situ diver point-count transects (Global Reef Expedition site data, 933 sites); it is not derived from these photographs.
• Algal cover 65% from the same transect.
• Transect mean 24 ± 6.4% SE (n = 4 transects; Living Oceans Foundation per-transect benthic data); the headline above is the expedition's station value.

Stressors

Condition, stated qualitatively: the great majority of coral in these frames is normally pigmented. A small number of individual colonies read pale or white — most visibly one plate-like colony (e.g., Image 4) — but a photograph cannot separate bleaching from recent tissue loss or predation, and no extent is estimated here. No crown-of-thorns seastars and no unambiguous disease lesions appear in the set. Anderson's notes record that needle coral (Seriatopora hystrix) on the 20.5 m transect looked bleached and unhealthy; the frames carry no depth, so they neither confirm nor contradict it.

Fish and other fauna

Fish are steady but not dense — schools of blue-and-yellow fusiliers (e.g., Image 2, Image 3), sweetlips and drummer along the crest (e.g., Image 21, Image 22, Image 25, Image 28, Image 31), damsels and small wrasse working the framework.

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One frame is a striking exception: an empty chambered nautilus shell lying on the reef (e.g., Image 1).

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Comparisons with other data

No other surveys have been conducted at this site to date. Within 5 km, ten independent stations recorded 3.9–66% hard coral cover between 1993 and 2023; the nearest, XL Catlin Seaview Survey at transect 12004, 0.65 km away, read 4.3–7.7% between 2014 and 2017.

Other notes

The survey itself is visible in three frames, which is useful and must not be read as reef structure: two show the PVC quadrat frame laid on the pavement (e.g., Image 11, Image 32), and one shows two divers working a transect line down the slope (e.g., Image 30).

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What the frames cannot settle: depth. Nothing in the set carries a readable gauge, so the shallow crest frames cannot be separated from the 9.5-21 m transect band by photograph alone, and the frames should not be treated as a picture of the surveyed depth specifically.