[Coral-List] GBR at risk of losing up to two thirds of living coral in the 2016 mass bleaching event.

[Juan Ortiz]

GBR at risk of losing up to two thirds of living coral in the 2016 mass bleaching event.


The ongoing bleaching event affecting the northern part of the GBR has been recently identified as the most severe bleaching event recorded for the area, with ~95% of reefs affected. However, the fact that coral bleaching has only impacted the northern GBR, leaving the central and southern GBR unaffected has been interpreted by some as a positive within this catastrophic event. However, recent studies have shown that the central and southern GBR have undergone significant declines in coral cover over the last 30 years, while the reefs in the north have remained in a stable higher coral state. To get a sense of the potential impact of the 2016 bleaching event, we calculated the total area of reef within each region and extrapolated average coral cover among the total reef area. We estimate the area covered by live coral for the whole GBR at approximately 193,000 ha. Of that amount, ~63% (121,000 ha) is located in the northern GBR, while 24% and 12% is located in the central and southern GBR respectively. Therefore, our estimates indicate that two thirds of the total coral stock of the GBR is currently at risk from this bleaching event, even though the northern region comprises a third of the total length of the GBR. With only four of the 520 surveyed reefs in the northern GBR showing no signs of coral bleaching, the 2016 mass coral bleaching event is likely to have a disproportionate impact on the health and future of the Great Barrier Reef.

Juan Carlos Ortiz and Glen Holmes

Dr. Juan Carlos Ortiz
Postdoctoral Research Fellow
Marine Spatial Ecology Lab
The University of Queensland
e-mail j.ortiz at uq.edu.au<mailto:j.ortiz at uq.edu.au>
Ph. +61 7 33651671