CoralTransplantation

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Coral Transplantation

What is coral transplantation?

Definition

Coral transplantation can be defined as the physical relocation of coral from a site of inhospitable conditions to where the coral is more likely to thrive. According to Edwards and Clark (1999), "the primary objectives of coral transplantation are to improve reef ‘quality’ in terms of live coral cover, biodiversity and topographic complexity.” [1] Therefore, coral transplantation may be implemented in order to move live coral in danger of destruction or poor conditions at one location to a transplantation site that may provide a more hospitable environment, or it may be implemented in order to assist in rebuilding a damaged or deteriorating site by moving coral from a healthy site to the less healthy one. Using scleractinian corals for coral transplantation is most common.

Benefits and Disadvantages

There are many advantages of coral transplantation that may give a community reasons to choose to transplant coral. The immediate increase in live coral cover is very appealing and encouraging to the community after they have been restored through coral transplantation. This, in turn, improves the aesthetics of a less diverse and less coral-abundant reef which can benefit the tourism industry in a coastal area. Along with increased coral cover, there is increased coral recruitment, which is the addition of coral juveniles (planula) in the coral reef that settle themselves and become polyps. With increased coral cover, rugosity and the number of sheltered locations for other marine organisms also increase, which helps establish a functional and diverse coral reef ecosystem.

Even though there are many benefits of coral transplantation, the disadvantages must be weighed against them. Transplanting coral often requires removing coral, whether it be a fragment or a whole colony, from a coral reef, and this can cause loss of diversity and coral abundance in the donor site. This also eliminates the chance of a coral fragment that is removed of establishing itself in the donor site and producing a new colony. There must be many precautions taken when removing coral from a donor site to ensure it will cause minimal effects on the ecosystem present. Transplanting coral can cause stress to the corals being moved and can result in reduced growth rates, higher mortality rates, and reduced fecundity of the stressed corals. High cost, another disadvantage of coral transplantation, can make coral transplantation a huge risk if the corals being moved are not able to survive or reproduce as well as corals already existing at the transplantation site. There is also the risk of attachment failure which happens when the transplanted corals are not able to properly attach to the substrate at the transplantation site or the man-made structures provided for the transplantation. Death of the coral follows attachment failure. If coral transplantation results in failure, disillusionment in the community can arise. There may seem to be no hope for reef restoration if much time and money was put into a failed coral transplantation project. This may lead to poor treatment of coral reefs by the community. [2] [1]

Methods

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Required conditions

Corals have many conditions which must be met in order for them to survive and thrive. These include suitable temperatures, turbidity, water quality, depth, and others. To have a successful coral transplantation, conditions must be appropriate for the corals to experience minimal amounts of stress during and after transplantation. Timing of the transplantation is also critical. In a study in the Eastern Mediterranean Sea, fish species that were able to efficiently consume algae and clear substrates for coral recruitment and growth allowed effective succession of corals after a large portion of the overgrown algae had been consumed. There must also be precautions taken to ensure that seasonal differences and currents are appropriate for coral transplantation so stress and attachment failure risks are reduced. [3]


Ways To Grow Coral

Coral fragments broken off by storms or other means can be transplanted to labs or nurseries for further growth. Planulae can also be cultured in labs and taken to nurseries for growth. After they are suitable to thrive in the wild, the coral is then planted at the transplant site. An alternative method involves taking either these fragments or whole coral colonies, and transplanting them directly to a transplant site. (Note: transplant sites are the designated site that is more hospitable for the coral to survive.) [2]

Attachment methods
  • Cement: This involves cementing the coral to a cement base then is then placed on the ground of the transplant site. It can be attached to the ground by cable ties.
  • Steel ties: This method involves attaching cable ties to the coral and then driving the other end into the ground to hold them in place.
New Technologies

Related studies

British Virgin Islands

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Elkhorn coral is a threatened species in the British Virgin Islands. A study took coral fragments that had been broken off by storms and transplanted them to a restoration site, where the coral fragments were then replanted to barren ground. It was found that the corals reattached themselves after approximately 3 months, and became large adult corals after 4 years. The methods described above required little training and could be done by volunteer recreational divers. [4]


Maldive Islands

Several species in the Maldive Islands were transplanted and observed to compare growth rates and mortality rates. Whole coral colonies were transplanted and cemented into place on a reef flat that had been degraded due to coral mining.

  • Acropora hyacinthus had the highest mortality rates (50% in two years)
  • Porites lobata had the lowest mortality rates (2.8% in two years)
  • Acropora divaricata had a high growth rate with relatively low mortality.

The results concluded that the species transplanted needs to be selected with care. The results were compared to other studies as well, and it was concluded that whether fragments or whole colonies are transplanted influences survival. There is a higher mortality rate at higher energy sites. The success rates suggested that coral transplantation should only be conducted when natural recovery is highly unlikely. [5]

St. John

A study conducted off of St. John Island (U.S.V.I) used storm-produced fragments of elkhorn, staghorn and finger corals. The fragments were moved from inhospitable habitats to other reefs. Cable ties were used to secure the fragments to the sea bottom of dead coral. Survival rates were found to be low for all species. One-third died from bleaching, disease, and predators, while the other two-thirds died from physical displacement. This suggested that cable ties were not the most effective method for reef reconstruction. [5]

Philippines

This study was designed to document the richness and abundance of different coral reef species due to the effects of coral transplantation of adult coral colonies, and to compare these characteristics at sites with and without coral transplants. Greater species richness and abundance were found at transplant sites compared to neighboring sites not receiving transplants and control sites over 100 meters from the transplant sites. This confirmed that the transplanted corals were responsible for the increased species diversity, and that organisms were not exchanged between the sites, because the empty plots and control plots had similar species diversities. Whole coral colonies were taken from degraded sites to undisturbed sites. Most of the corals were attached to bare rock surfaces with cement. Some sites attached the coral with green plastic screens that the transplants were tied to. The changes in diversity of the sites were then studied. The sites that used the plastic screens had in increase in the number of taxa present, and then began to decrease. The sites that used cement showed a small but steady increase in the number of taxa present. The study discouraged the movement of whole coral colonies, except in extreme cases where the coral will not rehabilitate on its own. [6]

Further Research Needs

Hopefully by next year, there will be more data and research regarding the long-term results and effects of coral transplantation. Alternative methods used would also expand the article, allowing for better analysis of the most successful methods. More research should be done on the most successful and least successful projects to compare and contrast them. For example, specific comparisons of different species of coral would be helpful in understanding why some transplantations are more successful than others. Furthermore, it would be helpful to see alternative solutions to avoid disillusionment if community and professional transplantations projects don't reach their desired outcome. It may also be interesting to look at a connection between government policies and coral transplantation.

Additional Resources

Presentation

http://prezi.com/_u0lbewwjzbr/?utm_campaign=share&utm_medium=copy&rc=ex0share

Lesson Plan

http://coraldigest.org/images/9/96/Coral_Transplantation_Lesson_Plan.pdf

References

  1. 1.0 1.1 Edwards, Alasdair J., and Susan Clark. "Coral Transplantation: A Useful Management Tool or Misguided Meddling?" Marine Pollution Bulletin 37.8-12 (1999): 474-87.Science Direct. Web.
  2. 2.0 2.1 Abelson, Avigdor. "Artificial Reefs vs Coral Transplantation as Restoration Tools for Mitigating Coral Reef Deterioration: Benefits, Concerns, and Proposed Guidelines." Bulletin of Marine Science 78 (2006): 151-56. Print.
  3. http://www.reefresilience.org/Toolkit_Coral/CCRd2_TransplantMethods.html
  4. http://www.sciencedaily.com/releases/2010/06/100603193925.htm
  5. 5.0 5.1 http://www.coralreef.gov/mitigation/transplanttion_rehabilitation.pdf
  6. Yap, Ht. "Local Changes in Community Diversity after Coral Transplantation." Marine Ecology Progress Series 374 (2009): 33-41. Web.