Reef Rescuers: Coral Gardening as an MPA Management Tool
Cousin Island Special Reserve, Seychelles
In 1998, the mass coral bleaching event, caused by the coupling of El Nino and the Indian Ocean Dipole, severely affected the reefs of the Seychelles Archipelago. The 1998 bleaching catastrophe decreased live coral cover by up to 97% in some areas and caused many reefs around the islands to collapse into rubble (which later became covered with algae). In the following decades, coral recovery has been extremely slow in the inner granitic islands of Seychelles. Despite the existence of numerous no-take Marine Protected Areas (MPA) – an effective tool to bolster coral reef recovery – it has taken almost 20 years to see coral cover at pre-1998 levels in most areas in the region. Due to continuous global threats, such as changes in climate and ocean chemistry, MPAs alone may not be enough to assist in the recovery of coral reefs in the Seychelles. Consequently, more active conservation strategies are needed to promote reef recovery and build reef resilience and to achieve the long-term conservation of coral reef ecosystem services.
The slow post-bleaching recovery motivated active restoration efforts in the inner islands of the Seychelles archipelago to assist in natural recovery. In 2010, Nature Seychelles launched the Reef Rescuers Project on Praslin Island. Financially supported by the United States Agency for International Development (USAID) and the Global Environment Facility (GEF) through the United Nations Development Program (UNDP), this climate adaptation coral restoration project seeks to repair coral bleaching damage in selected sites around Praslin and Cousin Island Special Reserve, a no-take marine reserve.
Through this project we are piloting the first-ever large scale active reef restoration project in the region using ‘coral gardening,’ a technique that involves collecting small pieces of healthy coral, raising them in underwater nurseries and then transplanting them to degraded sites that have been affected by coral bleaching. Forty thousand fragments of coral from 10 different branching/tabular species (Acropora hyacinthus, A. cytherea, A. abrotanoides, A. appressa, Pocillopora damicornis, P. grandis – senior synonym of P. eydouxi, P. meandrina, P. verrucosa, Stylophora pistillata, S. subseriata; species identification after Veron 2000 and nomenclature after the opens in a new windowWorld Register of Marine Species) have been raised in 13 underwater nurseries located inside the Cousin Island Special Reserve. Between November 2011 and June 2014, a total of 24,431 nursery-grown coral colonies were transplanted to 5,225 m2 (0.52 ha) of degraded reef within the Cousin Island Special Reserve.
With the onset of a weak-to-moderately strong El Niño-Southern Oscillation (ENSO) event starting late summer to early fall 2014 and continuing through 2016, we had a unique opportunity to determine the effectiveness of the choice of coral reef species (initially chosen based on survival rates during the last seawater warming anomaly) and the restoration process itself in alleviating the impact of warmer ocean temperatures. We are using standardized protocols to monitor the survival, reproduction, recruitment and bleaching response of donor and transplanted colonies. We continue monitoring at the transplantation site and two control sites, representing a healthy and degraded coral reef. Such monitoring allows us to evaluate the effectiveness of the restoration effort. Additionally, we are assessing the costs of large-scale reef restoration via coral gardening and the life cycle of coral reef restoration technology.
How successful has it been?
The long-term “success” of this mass transplantation is still being monitored but the project has already had positive outcomes. Forty-one practitioners from 11 countries have been exposed to reef restoration techniques by “on the job” work as volunteers up to three months on site, and eight experts have to date been formally trained through a full-time six-week classroom and field based training program. Before-and-after comparisons in coral cover at the transplanted site showed that the restoration project resulted in a 700% increase in coral cover, from about 2% in 2012 to 16% by the end of 2014. Similarly, we have documented a five-fold increase in fish species richness, a three-fold increase in fish density, and a two-fold increase in coral settlement and recruitment at the transplanted site. We also found that our coral transplants responded better to stressful conditions resulting from increased sea temperatures and a harmful algal bloom. The transplanted corals appear to recover faster and better than corals at other sites. The response of the transplanted reef to thermal stress bleaching is still being monitored. The preliminary analysis of the costs of reef restoration via coral gardening and the life cycle of coral reef restoration technology together with the ecological results so far support the application of large-scale, science-based coral reef restoration projects with long timescales to assist the recovery of damaged reefs. A proposal to scale up the coral farms to a mariculture venture so as to reduce costs through economies of scale has been accepted by the Seychelles government and funding is currently being sought.
Lessons learned and recommendations
A tool kit is currently being put together to highlight the lessons learned from the project. In summary, we have learned that:
- Survival of coral donor colonies is high.
- Survival of nursery colonies is high for the selected species listed above.
- There is a natural supply of corals (corals of opportunity) to be grown in the nurseries and that eliminate the need to re-fragment nursery-grown or donor colonies.
- Nurseries become floating reef ecosystems.
- Natural cleaning of coral nurseries and coral ropes reduces nursery maintenance and increases transplantation success.
- There is a positive transplantation effect on settlement and recruitment of new corals, fish diversity and density.
- The response of transplanted corals to bleaching causative events needs close monitoring to assess the effects of coral gardening on building bleaching resistance.
- There is citizen science interest internationally in receiving training on coral reef restoration.
- Partnerships with the tourism sector can be developed to establish coral gardens (seascaping) as a guest attraction and as a key part of the industry’s environmental management programs and Corporate Social Responsibility (CSR).
- Large-scale coral reef restoration needs to be considered as a cost-effective tool to include in the MPA manager’s toolbox.
Until 2015, funds to support the Reef Rescuers Project have been sourced and provided by opens in a new windowUSAID. Further financial support was received under the opens in a new windowGovernment of Seychelles-Global Environment Facility (GEF)-United Nations Development Project (UNDP) Protected Area Project in 2011.