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CORAL REEF KILL - COSTA RICA

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Invasive algae killing Costa Rican coral reef



A tropical algae thriving on fertilizers from hotel golf courses and 

badly treated sewage is killing one of Costa Rica's most important 

coastal reefs, scientists say. 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.





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_Caulerpa taxifolia_ is a marine green alga believed to have been 

accidentally introduced into the Mediterranean Sea. It forms 

continuous meadows from the surface to more than 30 meters (98 feet) 

deep; has been found in water to 100 meters (328 feet) deep 

(Boudouresque et al, 1995). Meadows of _Caulerpa taxifolia_ in the 

Mediterranean can attain exceptional densities, while in its native 

tropical seas the plant is usually isolated (Meinesz and Hesse, 

1991). It reproduces by fragmentation; sexual reproduction has not 

been observed at 10 meter (32.8 feet) depth, while reported biomass 

rates up to 700 g (dry weight) m2 (375 tons of wet biomass per acre) 

(Meinesz et al, 1994). _Caulerpa taxifolia_ protects itself by 

producing substances that are toxic to the Mediterranean's 2 main 

macro-herbivores, sea urchins and their eggs (as well as to hamsters 

and mice) (Lemee et al., 1993), and the fish _Sarpa salpa_ toxicity 



Although it appears native to the Caribbean, where previously it has 

not caused a problem, climate changes and water changes may have 

altered that previous  non-problematic state.





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2004

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Coral reef kills - USA (FL) (02)  20040327.0846

Coral reef kills - USA (FL)  20040320.0777

2002

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Coral reef kills, unknown etiology - Australia  20021023.5624

Coral reef kills, human waste suspected - Caribbean  20020627.4622

2000

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Coral reef kills - Belize  20000510.0713

1999

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Coral reef kills & potential human disease (02)  19990204.0161

Coral reef kills & potential human disease  19990124.0111

1998

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Coral reef bleaching & El Nino - Indian Ocean (02)  19981113.2187

Coral reef bleaching, El Nino effects - Indian Ocean  19980705.1246

Coral reef kills, etiology determined - USA  19980415.0693

1996

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White pox, coral reefs - Florida, USA (02)  19961231.2165

White Pox, coral reefs - Florida, USA  19961228.2160]

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