Posted 12 September 2011, by Tim Wall, DiscoveryNews, news.discovery.com
The last three decades haven’t been kind to the Belizean Barrier Reef, a 190 mile (300 kilometer) long section of the Mesoamerican Barrier Reef system.
First, two dominant species of coral died off due to disease and an El Nino event. Then in 2009, large sections of the barrier reef slid into deeper waters and were destroyed after a magnitude 7.3 earthquake shook the Caribbean.
The quake, which originated 81 miles (130 kilometers) northeast of La Ceiba, Honduras, caused landslides on the undersea slopes where the corals grew.
A team from the Florida Institute of Technology recently reported on the devastation in the journal Ecology.
The researchers had been monitoring the reefs in the lagoons off the coast of Belize from 1986 to 2009. When they returned in 2010, they found that about half of the reefs in a 375-square-kilometer (144-square-mile) area had gone the way of Atlantis. Only sediment and coral skeletal debris remained where the reefs once were.
The quake made an already dire situation worse.
Staghorn coral (Acropora cervicornis) was the dominant species in the area for the past 4000 years, according to radio-carbon dating of reef cores. But starting in 1986, staghorn was virtually wiped out in the area by a bacterial infection called white-band disease.
By 1995, lettuce coral had taken over as top coral. Then a harsh El Nino in 1998 brought high temperatures and wiped out the lettuce coral.
“The prior losses of both staghorn and lettuce corals drastically weakened the resilience of the coral assemblages on the reef slopes,” says lead author Richard Aronson of the Florida Institute of Technology in a press release.
“In other words, if neither white-band disease nor bleaching had occurred, staghorn coral might have continued its millennial-scale dominance of the areas not destroyed by the quake,” said Aronson.
After the staghorn and lettuce corals were gone, the area was taken over by seaweed, and an encrusting sponge which clung to the skeletons of the deceased corals.
By the time the quake struck there wasn’t much left of the reef Aronson’s team first studied in the 80’s. Much of what was left then sank into the depths.
The possibility of natural disasters should be incorporated into conservation strategies, said Aronson.
“The rhetoric of conservation often includes the appeal of preserving ecosystems so that our children’s children can enjoy Nature’s bounty,” said Aronson. “That translates to about 200 years, but ecosystems last far longer than three generations of their human stewards. We challenge marine conservationists to plan on a millennial scale.”
“Rare, catastrophic events are the backdrop to human actions. Those rare events should be factored into determining the sizes of marine reserves and their levels of protection, whatever else might be expected to happen along the way,” said Aronson.
“After all, a once-in-a-thousand-year disaster could still occur next week,” said Aronson.
Tim Wall reports from Siguatepeque, Honduras, where he teaches journalism to fifth and sixth grade public school students.
An island surrounded by reefs off the coast of Belize (Wikimedia Commons)
Coral and sponges on a reef in the Caribbean near Santa Lucia (Wikimedia Commons)
Healthy staghorn coral (Wikimedia Commons)