Global climate change is expected to cause serious damage to coral reef ecosystems during the coming 50 years. The rising sea surface temperatures and increasing ocean acidification are so serious global threats, that even the relevance of reef rehabilitation at the local level can be questioned.
The answer to those who doubt is that well-managed reefs which are relatively free of human impacts have shown resilience to coral bleaching and reef mortality. On the other hand, the badly managed reefs which were already affected by local impacts (such as pollution and overfishing), have often shown very limited recovery or no recovery at all.
When we try to manage human impacts in the world´s coral areas, reef rehabilitation techniques are an important tool. Rehabilitation together with other local management activities (regulation of fisheries, control of pollution, development of marine parks) is likely to improve ecosystem resilience. Those reefs which are well-managed will have a real possibility of surviving as productive and functional systems, when they are impacted by global environmental pressures.
The above is some of the key information included in the Reef Rehabilitation Manual edited by A.J. Edwards and published by Coral Reef Targeted Research & Capacity Building for Management Program, Australia, in 2010. The Manual, its sister publication Reef Restoration Concepts & Guidelines and other useful coastal management publications can be found at http://www.gefcoral.org. The direct link to the Reef Rehabilitation Manual is here: Reef Rehabilitation Manual
In spite of the considerable progress in coral reef restoration over the last 35 years, this field of science is still in its infancy. There have been a few successful rehabilitation projects already – and many others which have not met their goals.
Reef Rehabilitation Manual states that the primary aims of this handbook are:
- “to reduce the proportion of reef rehabilitation projects that fail”,
- “to introduce protocols for methods that could allow larger areas of degraded reef to be repopulated with corals whilst minimising collateral damage to reefs where corals are sourced”,
- “to highlight factors to take into consideration at the planning stage so as to minimise the risk of failure”, and
- “to underline the current limitations of reef rehabilitation”
The publication seeks to “disseminate protocols that will, on the one hand, increase the chance of success of active restoration projects and on the other, reduce the impact of these projects on the natural reef if they fail”.
The Manual tells us that normally a two-step process is required when we want to supply coral transplants for large scale rehabilitation projects. The steps are:
- small fragments of coral or coral spat (settled larvae) are reared in nurseries until they are big enough to survive on a degraded reef,
- the nursery-reared colonies are transplanted to stable reef areas (obviously attaching them securely is important)
Reef Rehabilitation Manual has three central technical chapters. They build on work and describe protocols which have been developed in several countries. The technical chapters help the reef manager construct and manage a nursery for farming of coral fragments, offer information on how to rear coral larvae for restoration, and give instructions for deployment of coral transplants on a degraded reef.
Finally, it is important to remember that the best alternative is to be proactive and avoid ecosystem degradation. The Manual provides this reminder: “Although restoration can enhance conservation efforts, restoration is always a poor second to the preservation of original habitats.”