Caulerpa taxifolia

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Posted by ptf on August 13, 2001 at 11:06:45:

Yep it was in California Dive News a few months ago and in
the Dive Log Magazine from New Zealand 2 years ago...Now from
the Wall Street Journal.

Europe Universities Rush to Fight Fast-Spreading Killer Sea Weed


GOLFE JUAN, France -- As tourists splashed in the shallows of this
Mediterranean resort, Alexandre Meinesz grappled with his nemesis 15 feet
underwater. He seized the creature and dragged it up. "It's the first time I've
seen it on this part of the sea floor," he sputtered through a snorkel.

Prof. Meinesz's foe was harmless-looking algae. This
dark-green seaweed clones itself, grows as much as an
inch a day and overpowers the local flora. Though safe
for human swimmers, it is toxic to fish that eat it. The
French call it "killer algae." Its Italian nickname is "alga

Prof. Meinesz, a 55-year-old biologist at the University
of Nice, has spent 10 years trying to stop the
marauding plant, technically known as Caulerpa
taxifolia. But his efforts have become tangled in
controversy. The plant has spread to France, Spain,
Italy, Croatia and Tunisia. In 1999, the weed was
discovered in the Pacific Ocean off San Diego, prompting the U.S. to ban its
sale and import. Back then, caulerpa was a popular decoration in home
aquariums since it grows easily and most fish don't eat it. Now a brochure from
the U.S. National Marine Fisheries Service warns: "If you see it, immediately
report it, but DO NOT disturb it!"

"There are lots of invasive species, but this thing is in a league of its own," says
Bob Hoffman, a biologist at the service. "It has the potential to totally overtake
the natural flora and fauna of California."

The Spanish have used an underwater tank to shoot electrically charged
particles at the plant. U.S. scientists built a large tent around a colony near San
Diego and smothered it with bleach. Prof. Meinesz has pinned his hopes on a
voracious Caribbean sea slug -- the only creature known to eat caulerpa and

The controversy over the algae began in 1989 when Prof. Meinesz saw a dense
patch growing near the Oceanographic Museum of Monaco, originally headed
by Jacques Cousteau. Prof. Meinesz was puzzled to find the tropical weed
surviving in cold water. In 1990, he published a report in a scientific journal
suggesting that a tougher strain of the weed had accidentally been released into
the Mediterranean by the museum.

The museum wasn't happy. It accepted that the algae
decorated its tanks but denied that it was harmful. Prof.
Meinesz was denounced as a scare-monger and a
publicity seeker. Some of his colleagues criticized him
for linking a marine menace with Mr. Cousteau, a
French hero famous for his love of the ocean.

But caulerpa continued to spread. In 1990, it was
found in France. Then it showed up in Italy, provoking
an uproar. Dive clubs went on alert. A local TV host
donned scuba gear and filed a live report from a
caulerpa-infested seabed.

The Monaco museum stuck to its guns. Its scientists first insisted that the plant
was beautiful and harmless. In 1995, three scientists funded by the principality
of Monaco published an article in the journal of the French Academy of
Sciences arguing that the algae had arrived not from its fish tanks, but from the
Red Sea. Prof. Meinesz and a colleague counterattacked in the same journal,
stating that the data had been selectively used and misrepresented the origin of
the weed.

The authorities waded in. France and the European Union sponsored research
programs on caulerpa, and in 1998, a United Nations workshop decided that
the algae could wreck the Mediterranean ecosystem and had to be controlled.
Some months later, caulerpa was added to the U.S. government's
noxious-weed list and banned.

Australian Origins

The academic war hasn't stopped. Last November, a team of scientists from
the University of Geneva, the University of Pisa and the University of California,
Fresno, published a report in Nature analyzing DNA from various caulerpa
samples. Their conclusion: Caulerpa originated off the southern coast of
Australia, not the Red Sea. Three months ago, a separate study confirmed
those results and also concluded that the "accidental introduction" into the sea
via an aquarium had clearly occurred and was "no longer under dispute."

Prof. Meinesz believes a genetically altered plant was originally acquired from
southern Australia by a public aquarium in Stuttgart, Germany, and then given
to the Monaco museum. Whether the museum accidentally dumped it into the
sea may never be known.

Francois Doumenge, who succeeded Mr. Cousteau as director of the museum
in 1988 and remains in that position today, denies the possibility. "Any escape
from a museum tank cannot reach the sea," he says, in a faxed response to
questions. He notes that the museum is perched on a 150-foot-high cliff and
says any fragments of caulerpa would be likely to drift six to 12 miles before
sinking to the seabed.

It may not really matter. Today, more than 32,000 acres of the Mediterranean
are infested with clumps of the algae, a ninefold increase since 1994, according
to measurements by Prof. Meinesz, who plots the invasion with brightly colored
tacks on a large map in his office. Unable to consume the toxic plant, many fish
have fled. In some places where the seabed has turned into vast caulerpa
"meadows," the fish population has fallen by 40%.

Caulerpa is hard to kill because of its weird biology. Composed of a single,
tube-like cell that can grow up to nine feet, the plant has only male parts. If a
small piece breaks off and lands elsewhere, it spontaneously sprouts new
progeny -- each a genetic clone of the original. So uprooting it by hand can
spread the infestation.

'Yellow Submarine'

Bernard Jaffrennou, a retired chemical engineer who lives in a small town more
than 100 miles west of Nice, has invented an elaborate solution: an undersea
tank. On a recent morning, the piano-size metal monster -- painted a bright
yellow -- was parked in a municipal lot, next to an old horse carriage. Mr.
Jaffrennou gave it a pat. "My yellow submarine," he said proudly.

It isn't easy to use. A hoist on a boat first lowers the quarter-ton contraption
into the water, and then it is pushed -- wheelbarrow style -- by a diver. While
traversing a caulerpa bed, it shoots out a spray of copper ions that poisons the
plant. The machine can zap a 50-square-yard area in about an hour but works
only on a seabed "flat as the American Midwest," says Mr. Jaffrennou. It has
seen action only twice -- off Spain.

Mr. Jaffrennou says he built the device and related models as a labor of love,
using about $1,300 in savings and funds from local authorities. Now he needs
more. The French environmental ministry is supportive but isn't ready to rent his
machine on a commercial basis, so the 73-year-old Mr. Jaffrennou plans to
wait. His wife, Jeanine, says: "I've had it. I want him to stop."

In Nice, Prof. Meinesz is equally undeterred. His university frowns on the algae
controversy and has rejected his request for a promotion seven times in as
many years, he says. But his eyes light up when he peers into a fish tank and
sees dozens of Caribbean slugs sucking the sap from caulerpa. He's trying to
breed a strain of the slug that can survive the colder waters of the
Mediterranean, but he faces a dilemma: What if the tiny killers themselves
multiply out of control?

"They're a hope," sighs Prof. Meinesz, "but only a hope."

Write to Gautam Naik at gautam.naik@wsj.com1

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