N. GBR - Blue (AU3975)

Setting

Global Reef Expedition station AU3975 on Unnamed Reef 11-039, far northern Great Barrier Reef (-11.2390, 143.2490), surveyed on 15 September 2014 on that day's second dive, in a Habitat Protection (Blue) Zone, where line fishing is permitted.

General benthic features

The notes describe a notably shallow reef: coral barely persists past 9-10 m, and much of the intervening sand wore a film of cyanobacteria (e.g., Image 6).

6

Where the reef held it built quickly, with transects estimated by eye rising from 5-20% near the sand line to 40-60% at 8-8.5 m across a highly rugose stretch of Stylophora pistillata, Lobophyllia, branching acroporids, and small massive poritids, with fungids, Platygyra, and Goniopora adding diversity. Twenty-six juvenile corals were counted across six transects; no bleaching, disease, or crown-of-thorns activity was recorded. Acropora was the most common coral genus on this station's transects (14% of the benthos), followed by Echinopora and Porites (4.7% each), Stylophora (3.7%), and Galaxea and Seriatopora (2.7% each); bare substrate covered 32%, the largest non-coral class. Among the algal classes on this station's transects, sediment-laden turf (16%) led, followed by turf (0.7%) and cyanobacteria (0.3%).

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 46% live coral cover against 17% total algal cover.
• Transect mean 46 ± 9.4% SE (n = 3 transects; Living Oceans Foundation per-transect benthic data); the headline above is the expedition's station value.

Stressors

Between the coral patches, a layer of cyanobacterial overgrowth covered much of the sand, as his notes record (e.g., Image 6). Regional context, not an observation here: surveyed about eighteen months before the 2016 mass bleaching, an event that severely bleached hundreds of reefs on the northern Great Barrier Reef (Hughes et al. 2017); 5-year mean annual maximum thermal stress at the Far Northern GBR virtual station is 11.1 degree heating weeks.

Comparisons with other data

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