Tropical reefs are easy to destroy and difficult to fix. It is estimated that global warming, unsustainable fishing, and pollution have already destroyed 20% of the world’s coral reefs. Recently, Virginia Garrison and Greg Ward of the United States Geological Survey (USGS) demonstrated how coral fragments that have broken loose during storms can be used to rebuild reefs. They reported their results in the October issue of Biological Conservation.
Garrison and Ward conducted their study in Virgin Islands National Park, on the island of St. John. They took fragments of coral that had been naturally dislodged from healthy reefs during storms. With plastic zip-ties, they re-attached these fragments to other reefs that had lost corals. After five years, the results were promising: 25% of fragments had living coral colonies, and only 31% had died. The remainder has been knocked off by waves.
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The majority of successful transplants in this study were Acropora palmate, an endangered Caribbean coral. Acropora palmata and another species in the study, A. cerivcomia, were major parts of the Caribbean reef ecosystem until a major die-off in the 1970s. This earned them the distinction of being the first corals listed as threatened by the US Endangered Species Act.
Garrison and Ward highlight the significant debate about reef restoration. Some biologists have argued that the extent of reef damage is too vast to make restoration worthwhile. In response, Garrison and Ward note the low cost of their approach: $21 per transplant, two-thirds of which is the salary of workers. Other methods of reef restoration include stabilization of reefs, removal of debris that can choke reefs, and the creation of rock piles to encourage the re-establishment of corals.
Citation: Garrison, Virginia and Greg Ward. 2008. Storm-generated coral fragments – a viable source of transplants for reef rehabilitation. Biological Conservation 141: 3089-2100 (October).
Locations in Virgin Islands National Park, St. John: Trunk Cay, Hawksnest Bay, Whistling Cay, Leinster Bay
Species: Acropora palmata, A. cervicornis, Porites porites
A. palmate at NOAA: www.nmfs.noaa.gov/pr/species/invertebrates/elkhorncoral.htm
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