Invasive Algae Killing Costa Rican Coral Reef
Date: 30-Aug-07
Country: COSTA RICA
Author: John McPhaul
The green, feather-like algae is spreading along the reefs
of Culebra Bay in Costa Rica's northwestern Gulf of Papagayo, a
popular scuba diving spot and home to a rare species of coral.
The algae blocks the sunlight and suffocates the reefs.
A tourism and construction boom along the palm tree-lined
beaches is creating nitrogen- and phosphate-rich waste that
feeds the algae, known as Caulerpa sertularioides, and Costa
Rica is only just becoming aware of the problem.
"It's an ecological disaster," said Cindy Fernandez, a
marine biologist with the nonprofit MarViva Association, who
alerted the Costa Rican government to the threat, which is now
being taken on by the state-run University of Costa Rica.
Scientists say about 80 percent of the reef area, which
stretches for about a mile and a half (2.4 km) along the coast
line, is covered in the algae.
The aggressive algae spreads when even the smallest sliver
comes loose, from the likes of strong currents or dive boats
dropping anchor, to root itself in another part of the reef.
Even the sweep of a diver's hand or the kick of a diver's
fin can send a fragment swirling away to start another patch.
That means experts cannot pull it up like weeds.
"If you pull it up it will reproduce faster," said Jenny
Asch, coordinator of the government's marine conservation
program, who is leading efforts to find a way to eradicate the
algae.
If left unchecked, the algae could also severely damage
the ecosystem of the bay, allowing non-native species of fish
to come in and displace the native species.
The highly invasive Mediterranean strain of the algae,
Caulerpa taxifolia, was discovered in Southern California in
June 2000, where scientists have used solid chlorine blocks to
eradicate the pest.
Costa Rican scientists do not yet know if similar
eradication techniques will work on Caulerpa sertularioides.
The algae is the latest challenge facing Costa Rican
authorities as the Central American country struggles with
conserving its unique tropical biodiversity while attracting
tourists and marketing itself as an ecotourism paradise.