More than 50% of the world's coral reefs are threatened
Two hundred sea urchins are being released into the Atlantic off the Florida Keys, in an attempt to save coral reefs.
Scientists hope the sea creatures will restore the health of coral by feeding on algae that smother the reefs.
Florida has lost more than half of its coral in the last 10 years due to a number of factors, including pollution, fishing, and increasing sea temperatures.
In the next phase of the experiment, marine biologists plan to release young coral raised in the laboratory and grown in offshore nurseries.
Ten percent of the world's coral reefs have been completely destroyed or suffered severe damage, while 56% are threatened.
One of the factors implicated in the decline of reefs has been the loss of sea urchins, which graze on coral-smothering algae.
In 1983, one species of sea urchin was almost completely wiped out by a disease.
This has led to a dramatic increase in the growth of fleshy seaweeds and algae, which prevent tiny coral larvae from rebuilding the reef.
Recovery plan
In one of the first attempts to restore the health of coral reefs, scientists from the National Oceanic and Atmospheric Administration (NOAA) and two US universities are setting the first batch of young sea urchins free.
The sea urchins will be released at an experimental site on a reef off Key Largo.
Experts from the University of Miami and the University of North Carolina at Wilmington will monitor the sea urchins, to see whether they survive.
The next step is to release young coral capable of rebuilding reefs in the same area. It is being raised in huge floating nursery chambers developed by colleagues on the Great Barrier Reef off northern Australia.
However, even if all goes to plan, restoring the health of coral reefs will be a long, slow process.
Coral, which grows at the rate of only a
centimetre a year, takes thousands of years to
form. Any recovery will not take place for
decades or centuries.
-- Anonymous, July 28, 2001