Why are Coral Reefs Valuable? — audio podcast
Restoration biologists assess the damaged patch reef.
A recently published study of coral restoration in Florida Keys National Marine Sanctuary illustrates how a patch reef – an isolated, comparatively small coral outcrop located in shallow waters – can survive and even thrive nearly a decade after being hit by the hull of a boat.
In August 2002, the 36-foot- long Lagniappe II ran aground on just such a reef near Key West, damaging approximately 376 square feet of living coral – mostly boulder star coral, a mounding species and a primary reef-builder in the Florida Keys. Restoration biologists stabilized the toppled and dislodged corals and pieced them back together – all 473 fragments – with a special cement mixture that hardens underwater.
Sanctuary Science Coordinator (acting) Scott Donahue explains that to create the “coral cement,” the restoration team “started with off-the-shelf Portland cement and mixed in plaster of Paris so that it would harden almost immediately.” Once the mix was right, they proceeded to “reassemble the corals in a process that was much like laying bricks.”
“They strategically affixed globs of cement on the bare reef, placed the coral fragments into the cement, then built the cement up to the edge of the living coral to protect the exposed limestone skeleton from erosion and predation,” he continues.
Donahue notes that world renowned coral researcher Harold Hudson, PhD, aka the “Reef Doctor,” pioneered this method to restore the geology of the reef in the 1980s, when he discovered that coral fragments of 10 square inches or more could be stabilized in this way.
“This is the first time that the approach has been scientifically proven ‘successful” at this scale,” says Donahue.
The restoration team pieced together 473 coral fragments.
To track the progress of their restoration efforts, the sanctuary partnered with the National Coral Reef Institute of Florida’s Nova Southeastern University Oceanographic Center. They used digital photography and specialized computer software to document and count the types and amounts of coral in the damaged area as well as at a nearby reference site.
Baseline photos and statistics were taken in late 2002, and the site was visited approximately every two years thereafter. By 2009, the reattached coral fragments could not be distinguished from the nearby uninjured coral colonies. By 2010, the amount of coral at the restoration site was greater than that at the reference site.
With countless vessels continuously cruising its 220-mile stretch of islands, the Florida Keys National Marine Sanctuary receives reports of hundreds of vessel groundings every year. While most incidents involve boats less than 60 feet long, many still damage centuries-old colonies of fragile, slow-growing corals. Sanctuary staff emphasize that most groundings are preventable through preparation, patience, and experience.
The owner of Lagniappe II paid $56,671 in a negotiated settlement. The funds were used to pay for the emergency response, damage assessment, and part of the cost of restoring and monitoring the reef.
The lessons learned from this study will prove invaluable in future efforts to restore coral reefs and conserve these unique and vital habitats.
Map of Lagniappe II vessel grounding location on August 8, 2002.