N. GBR - Blue (AU238141)

Setting

Global Reef Expedition station AU238141 on Unnamed Reef 128 (reef ID 11-238), far northern Great Barrier Reef (-11.9191, 143.8412).

General benthic features

The notes record 30-40 m visibility, a swath of bottlebrush Acropora beneath the boat, and reef running to at least 30 m, with a 15 m transect estimated by eye at 60% cover while shallower rubble flats near 5 m held almost none. One shallow frame, taken close under a rippled surface, shows a dense pavement of small colonies packed together with barely a gap: cream and lavender corymbose Acropora, pink Pocillopora, encrusting and finger Porites, and bright green algal tufts sprouting between them (e.g., Image 3).

3

Another is a near-solid meadow of pale corymbose Acropora running out into hazy blue (e.g., Image 4).

4

A third looks along a steep face carrying low-relief mixed coral and turf with a wide cloud of chromis strung out over open water (e.g., Image 5).

5

One downward frame is algal-turfed rubble and dead pavement, red and rust-colored (e.g., Image 1).

1

Acropora was the most common coral genus on this station's transects (18% of the benthos), followed by Porites (12%), Isopora (9.1%), Diploastrea (7.5%), Stylophora (3.0%), and Seriatopora (2.3%); bare substrate covered 28%, the largest non-coral class. Among the algal classes on this station's transects, crustose coralline algae (9.6%) led, followed by sediment-laden turf (5.8%).

Coral cover

• Reference: Khaled bin Sultan Living Oceans Foundation, Global Reef Expedition (in situ transect)
• The expedition's in situ point-count transects at this station recorded 55% live coral cover against 15% total algal cover.
• Transect mean 51 ± 5.3% 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; one depth had a single transect).

Stressors

Recorded condition: Anderson wrote that Seriatopora hystrix looked terrible virtually everywhere, with dead colonies at 15 m alongside dead Acropora, and only one shallow patch of possibly healthy S. hystrix. One frame shows two bleached branching colonies side by side: a thick-tipped colony stark white with its polyps still visible and a fine-branching colony white-cream beside it (e.g., Image 13).

13

Regional context only: about eighteen months before the 2016 mass bleaching, in a sector it hit severely; 5-year mean annual maximum thermal stress at the Far Northern GBR virtual station is 11.1 degree heating weeks. No crown-of-thorns starfish (COTS) or other corallivores evident.

Comparisons with other data

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

Dive record

It was dived on 28 September 2014.

Other notes

Reef name: Anderson's field notes, his sheet, and his photo folder label this station AU128141 on 'Unnamed Reef 128'; the expedition's field report itinerary (28 September 2014), the station code AU238141, and the LOF map name the reef UN Reef 11-238. The pin keeps its station code. The page leads with his dive-log name, with the reef ID 11-238 second.