Two coral researchers examined
the reefs off Bonaire in January
after divers noticed strange
white lesions on star and brain
corals. Dr. Thomas J. Goreau
and Dr. James Cervino found
something they had never seen
before, huge patches of dead
coral, bright white where the
skeleton had been exposed after
tissue had died; the skeleton
itself was crumbling away.
“We were horrified,” said Dr.
Goreau. “It looks like someone
poured acid over the top of the
coral. The skeleton itself is
dissolved. I’ve been looking at
reefs probably longer than
anyone else alive and I’d never
seen it before. It’s attacking at a
speed and with a level of damage
that is unprecedented.”
Rapid wasting disease, which
can spread several inches across a coral head in a day, is all over
the reefs of Bonaire. Since
January, it has been spotted in
Mexico, Aruba, Curaçao,
Tobago, Grenada, and St. John’s,
an area spanning 2,000 miles.
Rapid wasting disease is only
one among many mysterious
diseases attacking corals. In the
last few years corals from the
Caribbean to the Philippines
have been quickly succumbing
to diseases never before seen.
“We’re all stunned at the
rapidity with which these new
diseases are occurring,” said Dr.
James W. Porter of the University
of Georgia. “The problems
are occurring at all depths and
the number of species affected is
increasing.”
Because of the newness of the
diseases, recognizing whether a
coral is healthy or sick can be
difficult. For example, rapid
wasting disease, which exposes a
white, crumbling skeleton, is
easily mistaken for anchor
damage or parrotfish bites.
Some speculate that stresses
like bleaching, sedimentation,
and pollution have pushed
corals to the point where they
are no longer able to fend off
diseases. However, Dr. Goreau
says that “most diseases don’t
correlate with each other or any
known environmental stress. In
Bonaire, rapid wasting disease is
having a devastating impact, yet
the reefs there are so clean.”
Others have suggested that
erosion and dumping sewage and
oil waste into the sea have brought
new pathogens in contact with
corals. For example, sea fan disease,
discovered just four years ago, is
widespread in the Caribbean. It’s
caused by a highly opportunistic
fungus that adheres to sediment;
after being washed into the sea,
it grows when it encounters a sea
fan. “It’s a terrestrial organism
that has crossed the land-sea
barrier,” Dr. Harvell said.
Cures for sick corals are a
long way off. While some have
suggested applying antibiotics to
the reefs, others caution about
the unknown hazards of dispensing
a drug that can destroy beneficial
bacteria as well as harmful
ones. Furthermore, the pathogens
may not be bacteria at all.
Researchers have had the
most luck treating black band
disease by vacuuming off the
diseased band of tissue. But that
is impossible for quickly spreading
diseases such as the white
plague. In four months in 1995,
it spread more than 100 miles,
jumping from one to 17 species
of corals.
Sometimes, however, no
treatment can be the best cure.
Once a disease is allowed to rage
through an area, any healthy,
resistant individuals left can
rebuild a tougher population.
However, Dr. Goreau says,
sponges, coralline algae, and sea
urchins are also succumbing to
new illnesses, further threatening
the health of reef communities.
Dr. Cervino is soliciting
reports of new outbreaks of
coral diseases from observers.
His e-mail address is
cnidaria@earthlink.net.
A version of this article, by
Carol Kaesuk Yoon, originally
appeared in the New York Times.