Invasive Algae Killing
Costa Rican Coral Reef
By John McPhaul,
Alertnet.org
SAN JOSE, - 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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