N. GBR - Green (AU74147)

Setting

This Global Reef Expedition station (AU74147) lies on the northern Great Barrier Reef, Australia, and was surveyed on 29 September 2014 on a dive to 22.2 m. The eleven frames in the set show a shallow reef framework built into a continuous slope of mixed coral that ran out to a reef edge and dropped into open blue water. At the foot of the slope, bommies crowned with pale lilac soft corals and small massive mounds stood on clean sand, one flank carpeted in a dark brown encrusting growth (e.g., Image 8).

8

General benthic features

Coral covered the framework almost wall to wall, with very little bare rock showing between colonies (e.g., Image 2).

2

Growth forms were mixed: corymbose and bushy branching colonies in tan, cream, lavender-pink, and purple, a bright yellow knobby branching colony, blue-tipped branching colonies, an orange-brown laminar colony, and lobed massive mounds, interleaved with leathery soft corals with lobed crowns (e.g., Image 1).

1

Large lobed massive mounds rose among the branching colonies, with a pink knobby colony, a yellow-green corymbose colony, and tabular colonies against the skyline (e.g., Image 7).

7

In front of one such mound, a brown-purple arborescent Acropora thicket with white growing tips sheltered small orange fish (e.g., Image 10).

10

Farther down the slope, a bright yellow foliose colony of scrolled, overlapping plates spread across the reef among tabular, corymbose, and small massive colonies (e.g., Image 9).

9

At the reef edge, a large corymbose colony with white growing tips stood beside a meandroid brain colony and a massive mound, with turf and red-brown algae confined to the dead rock at its base (e.g., Image 4).

4

Close in, a stark-white, bleached branching colony grew against a mound of long, tube-like polyps, with a tree-like soft coral behind and dark sponges on the rock below (e.g., Image 6).

6

Just above the drop, a large brown arborescent soft coral shared the rock with orange and purple encrusting growths and a brown-and-white honeycomb-patterned sponge-like growth (e.g., Image 5).

5

Coral cover

• Reference: Khaled bin Sultan Living Oceans Foundation, Global Reef Expedition (in situ transect)
• Live hard coral cover measured 79% on in situ benthic transects during the Khaled bin Sultan Living Oceans Foundation Global Reef Expedition, against algal cover of just 7.8% of the benthos.
• Transect mean 77 ± 4.5% SE (n = 8 transects; Living Oceans Foundation per-transect benthic data); the headline above is the expedition's station value (the headline weights each depth equally).

Stressors

The 2014 dive notes for this site record most needle corals looking bad, with sickly Seriatopora hystrix on transects at 14.7, 10, and 10.5 m, and crown-of-thorns-damaged Acropora on one transect at about 15 m (Anderson's GBR field notes, 2014). One branching colony in the photographs is bleached: stark white with its tissue intact, beside tan-to-purple branching colonies of the same growth form (e.g., Image 6).

Fish and other fauna

Small orange fish sheltered among the branching colonies (e.g., Image 3).

3

Two black polyclad flatworms with orange-and-white margins crept over a rock face beside a small meandroid coral and a gray sponge. A dark-bodied fish and a yellow-and-silver damselfish worked the reef edge, with small planktivorous fish in the blue water beyond (e.g., Image 7, Image 10).

Comparisons with other data

No other surveys have been conducted at this site to date. Within 5 km, three XL Catlin Seaview Survey stations recorded 16–32% hard coral cover between 2012 and 2016; the nearest, XL Catlin Seaview Survey at transect 15022, 2.79 km away, read 17–32% between 2012 and 2016.

Dive record

The dive began at 08:54 and lasted 61 minutes, per the LOF fellowship 2016 workbook.