A network of refugia makes the Great Barrier Reef more resilient to injury by providing emergency resources for restoring damaged areas

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The Great Barrier Reef, located just off Australia’s northeastern coast, is Earth’s largest coral reef system. It is home to 400 kinds of coral and thousands of other species. Threats like bleaching due to climate change, cyclones and invasive species can cause serious damage to these critical marine habitats.  

But when disaster strikes a reef, its neighbors can provide emergency aid to help restore it. Researchers say the best “rescue reefs,” known as refugia, have three important traits. First, historical patterns show they are less likely than others in the system to be inundated by warm water that leads to bleaching due to their location. Second, models of ocean currents suggest they are sufficiently connected by moving water to other reefs in the system during spawning season. This link helps coral larvae and other living things travel to and colonize the devastated areas to replenish them. Third, surveys show refugia are less likely than others to be infested with invasive crown-of-thorns starfish, whose larvae could travel to the injured reefs along with the desirable coral larvae. 

In recent research, scientists mapped reefs that have each of these helpful traits. By combining the maps, they identified a few protected and connected areas. Each can serve as a seed for other parts of the Great Barrier Reef after they sustain injury. Keeping these refugia safe from damage such as development and pollution can boost the overall resilience of the Great Barrier Reef, scientists say.

Many disturbed natural and human systems could benefit from this ecosystem approach to disaster recovery. Fire ravages forests. Floods destroy cities. Pandemics devastate economies. To use it, we must first identify likely threats to the system. Next, we should look for parts of the system that are less vulnerable to these threats. Does a forest contain isolated patches of trees that are less susceptible to fire? Is there high ground in a community that would be safe from a flood? Where are a city’s essential businesses that must operate through an emergency? Then we must work to protect these valuable assets from other sources of destruction, such as logging, urban blight or  poor business practices. Identifying threats and safeguarding refuge areas that are particularly important to recovery will help the whole system thrive after adversity.

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“Here, we reveal that around 100 reefs of the GBR, or around 3%, have the ideal properties to facilitate recovery of disturbed areas, thereby imparting a level of systemic resilience and aiding its continued recovery. These reefs (1) are highly connected by ocean currents to the wider reef network, (2) have a relatively low risk of exposure to disturbances so that they are likely to provide replenishment when other reefs are depleted, and (3) have an ability to promote recovery of desirable species but are unlikely to either experience or spread COTS outbreaks.” (Hock et al. 2017:1)

Journal article
Connectivity and systemic resilience of the Great Barrier ReefPloS BiologyNovember 28, 2017
Hock K, Wolff NH, Ortiz JC, Condie SA, Anthony KRN, Blackwell PG, et al.

Journal article
Seeking resilience in marine ecosystemsScienceMarch 2, 2018
Darling, ES, and Côté, IM

Journal article
Building resilience into practical conservation: identifying local management responses to global climate change in the southern Great Barrier ReefCoral ReefsMarch 7, 2010
Maynard, JA, Marshall, PA, Johnson, JE, & Harman, S

Journal article
The future of resilience-based management in coral reef ecosystemsJournal of Environmental ManagementMarch 1, 2019
Mcleod E, Anthony KR, Mumby PJ, Maynard J, Beeden R, Graham NA, Heron SF, Hoegh-Guldberg O, Jupiter S, MacGowan P, Mangubhai S

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