Costa Rica: Caño Island Coral Reef Restoration

Project Stage:
Completed

Start Date:
1984-01-01

End Date:
1989-12-31

Primary Causes of Degradation

Degradation Description

The 1982-1983 El Niño warming event cause widespread and catastrophic coral mortality across this part of the Pacific. Since that time there have been several secondary disturbances (a massive dinoflagellate bloom in 1985, continued strong upwellings and El Niño events) which have affected reefs all around Caño Island. Additional concerns have expanded in recent years, among them increasing sedimentation, oil and pesticide pollution, coral extraction for sale to tourists, and now climate change.

Reference Ecosystem Description

Reefs in the Eastern Pacific are composed of 18 species of scleractinian and 3 species of hydrozoan corals. Around 4000 years ago the sea level rose to the point that allowed for reef building to occur on the continental shelf, the average accumulation rates of coral reefs in this part of the Pacific are much lower than elsewhere in the ocean, resulting in reefs that are commonly small, isolated, and monospecific thickets of Pocillopora o massive colonies of Porites and Pavona that grow 5-6 m high and 150 wide. Eastern Pacific reefs have to deal with seasonal upwellings of colder water which in many areas is the cause of their restricted range. Along the 1016 km long Pacific coast of Costa Rica 44 reefs or coral communities have been identified, with only two in protected areas, the Cocos and Caño islands.

Project Goals

Permanent monitoring of the reef recognized early on in the project that there was an increasing mortality of coral reefs in the area. The mortality of the 1982-1983 El Niño events highlighted the need to evaluated how to support and augment corals through restoration. Futher events such as a dinoflagellate bloom in 1985 that surrounded the entire island and predation by the sea star Acanthaster planci indicated that there was an ongoing problem with recovery of the reefs. Although these were natural causes, the extraction of corals for sale as souvenirs as another stress on the population, going so far as to indicate that Pocillopora eydouxi was exploited nearly local and even regional extinction, leaving only an extremely small population. The slow recovery process and poor reproduction would not allow adequate growth to compensate for intense natural and induced destruction of the reef frameworks.

Monitoring

The project does not have a monitoring plan.

Stakeholders

Coral reefs are the marine equivalent of tropical forests in terms of both diversity and productivity. The reduction of coral reefs due to seasonal fluctuations such as El Niño events, or climate change in general. The restoration of coral reefs then falls under the purview of being a critical component to any conservation effort. The project sought to answer some of the critical questions associated with reefs, including the role that biological reserves can play in preserving biodiversity, knowledge of population structure, and the role of disturbances. The relevance of restoration in this project is not understated as there is a continual, marked decline in reefs throughout the area, and their known recovery differs from other areas in the Pacific. The poor reproduction and low density of viable adult populations will not allow for adequate growth to compensate for intense natural or induced destruction of free frameworks, which affect the long-term build up of coral reefs.

Description of Project Activities:
Once the study sites were located, one to five fragments (4-7 cm in size) were broken from surviving colonies of pocilloporid coral species found around the island at different depths and transported in 20L buckets with water to the transplanting sites; coral were generally transported less than 5 km. An area of 10 square meters was established at each locality and coral fragments were placed on the reef frame by attaching them with wire to 30-cm-long steel stakes (8mm in diameter). A total of 58 and 52 fragments were transplanted at Richmond and Platanillo reefs, respectively. New areas at Platanillo were created during 1988-1989, with almost 40 square meters and 200 fragments transplanted, but only the original 52 fragments were considered in the analysis of the project. Pocilloporid corals were only transplanted on top of old pocilloporid frameworks.

Ecological Outcomes Achieved

Eliminate existing threats to the ecosystem:
The transplanting method used in the Caño Island was successful in both habitats. After three years of monitoring the transplanted Pocillopora spp. fragments, data indicated mortalities of only 21% and 17% on Richmond and Platanillo reefs, respectively. Furthermore, the numbers of additional colonies created by fragmenting from the parent colonies were 24 and 60, respectively. This is an increase in new colonies of 41% for Richmond and 115% for Platanillo over the original numbers of transplanted colonies. The increase started the first year and occurred because the transplanted fragments attached themselves rapidly to the reef framework (in less than 5 months). There was further data to indicate a high capacity to regenerate tissue and grow. After attaching, each fragment develops into a colony with several branches, and may then fragment and form new colonies. These new fragments disperse by current, waves, or tides until they are fixed to a crevice or hole in the framework. Some colonies measured up to 21 cm in diameter after three years, and the area presently covered with Pocillopora clusters at Platanillo is close to 30 square meters, more than twice the original area. However, the project indicated that generalizations for reef management should be made cautiously. Results that were seen in other regions may not be applicable since both physical and biological conditions vary greatly among localities.

Factors limiting recovery of the ecosystem:
The physical scale of restoring coral reefs along a more than 1000 km long coast line is seen as a prohibitive concern. Although the project was shown to be technically feasible and successful it was unable to address those challenges that are more global in scope, such as global warming and acidification of the oceans.

Socio-Economic & Community Outcomes Achieved

Economic vitality and local livelihoods:
In the case of Caño Island, the development of it as a Biological Preserve was done so without having prior knowledge of the population structure of the reefs and associated organisms. However, through the project's permanent monitoring and assessments of the magnitude, intensity, range, and frequency of disturbances provided a foundational set of data to answer basic questions on the role of biological reserves in preserving biodiversity in this region. The Caño Island Biological Reserve is a true reserve of genetic material and coral diversity.

Long-Term Management

Because it is part of a permanent biological reserve, Caño Island allows for the development of a more permanent process of exporting populations to restock reefs in other exploited areas, once the reefs are restored. The importation of clones of surviving individuals as can be found can enhance the restoration by introducing rare coral species before another disturbance arrives, and before people can remove the last individual from nearby reefs.

Sources and Amounts of Funding

Funding was received from the Vicerrectoria de Investigacion, Universidad de Costa Rica, the Smithsonian Tropical Research Institute Short-term Fellowship Program, and the National Science Foundation.

Other Resources

Guzmán, Hector M. 1991. Restoration of Coral Reefs in Pacific Costa Rica. Conservation Biology. 5(2):189-195.

Primary Contact

Organizational Contact