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http://www.nytimes.com/2008/08/03/science/earth/03jellyfish.html

August 3, 2008

Stinging Tentacles Offer Hint of Oceans' Decline

By ELISABETH ROSENTHAL

BARCELONA, Spain - Blue patrol boats crisscross 
the swimming areas of beaches here with their 
huge nets skimming the water's surface. The 
yellow flags that urge caution and the red flags 
that prohibit swimming because of risky currents 
are sometimes topped now with blue ones warning 
of a new danger: swarms of jellyfish.

In a period of hours during a day a couple of 
weeks ago, 300 people on Barcelona's bustling 
beaches were treated for stings, and 11 were 
taken to hospitals.

From Spain to New York, to Australia, Japan and 
Hawaii, jellyfish are becoming more numerous and 
more widespread, and they are showing up in 
places where they have rarely been seen before, 
scientists say. The faceless marauders are 
stinging children blithely bathing on summer 
vacations, forcing beaches to close and clogging 
fishing nets.

But while jellyfish invasions are a nuisance to 
tourists and a hardship to fishermen, for 
scientists they are a source of more profound 
alarm, a signal of the declining health of the 
world's oceans.

"These jellyfish near shore are a message the sea 
is sending us saying, 'Look how badly you are 
treating me,' " said Dr. Josep-María Gili, a 
leading jellyfish expert, who has studied them at 
the Institute of Marine Sciences of the Spanish 
National Research Council in Barcelona for more 
than 20 years.

The explosion of jellyfish populations, 
scientists say, reflects a combination of severe 
overfishing of natural predators, like tuna, 
sharks and swordfish; rising sea temperatures 
caused in part by global warming; and pollution 
that has depleted oxygen levels in coastal 
shallows.

These problems are pronounced in the 
Mediterranean, a sea bounded by more than a dozen 
countries that rely on it for business and 
pleasure. Left unchecked in the Mediterranean and 
elsewhere, these problems could make the swarms 
of jellyfish menacing coastlines a grim vision of 
seas to come.

"The problem on the beach is a social problem," 
said Dr. Gili, who talks with admiration of the 
"beauty" of the globular jellyfish. "We need to 
take care of it for our tourism industry. But the 
big problem is not on the beach. It's what's 
happening in the seas."

Jellyfish, relatives of the sea anemone and coral 
that for the most part are relatively harmless, 
in fact are the cockroaches of the open waters, 
the ultimate maritime survivors who thrive in 
damaged environments, and that is what they are 
doing.

Within the past year, there have been beach 
closings because of jellyfish swarms on the Côte 
d'Azur in France, the Great Barrier Reef of 
Australia, and at Waikiki and Virginia Beach in 
the United States.

In Australia, more than 30,000 people were 
treated for stings last year, double the number 
in 2005. The rare but deadly Irukandji jellyfish 
is expanding its range in Australia's warming 
waters, marine scientists say.

While no good global database exists on jellyfish 
populations, the increasing reports from around 
the world have convinced scientists that the 
trend is real, serious and climate-related, 
although they caution that jellyfish populations 
in any one place undergo year-to-year variation.

"Human-caused stresses, including global warming 
and overfishing, are encouraging jellyfish 
surpluses in many tourist destinations and 
productive fisheries," according to the National 
Science Foundation, which is issuing a report on 
the phenomenon this fall and lists as problem 
areas Australia, the Gulf of Mexico, Hawaii, the 
Black Sea, Namibia, Britain, the Mediterranean, 
the Sea of Japan and the Yangtze estuary.

In Barcelona, one of Spain's most vibrant tourist 
destinations, city officials and the Catalan 
Water Agency have started fighting back, trying 
desperately to ensure that it is safe for 
swimmers to go back in the water.

Each morning, with the help of Dr. Gili's team, 
boats monitor offshore jellyfish swarms, winds 
and currents to see if beaches are threatened and 
if closings are needed. They also check if 
jellyfish collection in the waters near the 
beaches is needed. Nearly 100 boats stand ready 
to help in an emergency, said Xavier Duran of the 
water agency. The constant squeal of Dr. Gili's 
cellphone reflected his de facto role as Spain's 
jellyfish control and command center. Calls came 
from all over.

Officials in Santander and the Basque country 
were concerned about frequent sightings this year 
on the Atlantic coast of the Portuguese 
man-of-war, a sometimes lethal warm-water species 
not previously seen regularly in those regions.

Farther south, a fishing boat from the Murcia 
region called to report an off-shore swarm of 
Pelagia noctiluca - an iridescent purplish 
jellyfish that issues a nasty sting - more than a 
mile long. A chef, presumably trying to find some 
advantage in the declining oceans, wanted to know 
if the local species were safe to eat if cooked. 
Much is unknown about the jellyfish, and Dr. Gili 
was unsure.

In previous decades there were jellyfish problems 
for only a couple of days every few years; now 
the threat of jellyfish is a daily headache for 
local officials and is featured on the evening 
news. "In the past few years the dynamic has 
changed completely - the temperature is a little 
warmer," Dr. Gili said.

Though the stuff of horror B- movies, jellyfish 
are hardly aggressors. They float haplessly with 
the currents. They discharge their venom 
automatically when they bump into something warm 
- a human body, for example - from 
poison-containing stingers on mantles, arms or 
long, threadlike tendrils, which can grow to be 
yards long.

Some, like the Portuguese man-of-war or the giant 
box jellyfish, can be deadly on contact. Pelagia 
noctiluca, common in the Mediterranean, delivers 
a painful sting producing a wound that lasts 
weeks, months or years, depending on the person 
and the amount of contact.

In the Mediterranean, overfishing of both large 
and small fish has left jellyfish with little 
competition for plankton, their food, and fewer 
predators. Unlike in Asia, where some jellyfish 
are eaten by people, here they have no economic 
or epicurean value.

The warmer seas and drier climate caused by 
global warming work to the jellyfish's advantage, 
since nearly all jellyfish breed better and 
faster in warmer waters, according to Dr. 
Jennifer Purcell, a jellyfish expert at the 
Shannon Point Marine Center of Western Washington 
University.

Global warming has also reduced rainfall in 
temperate zones, researchers say, allowing the 
jellyfish to better approach the beaches. Rain 
runoff from land would normally slightly decrease 
the salinity of coastal waters, "creating a 
natural barrier that keeps the jellies from the 
coast," Dr. Gili said.

Then there is pollution, which reduces oxygen 
levels and visibility in coastal waters. While 
other fish die in or avoid waters with low oxygen 
levels, many jellyfish can thrive in them. And 
while most fish have to see to catch their food, 
jellyfish, which filter food passively from the 
water, can dine in total darkness, according to 
Dr. Purcell's research.

Residents in Barcelona have forged a prickly 
coexistence with their new neighbors.

Last month, Mirela Gómez, 8, ran out of the water 
crying with her first jellyfish sting, clutching 
a leg that had suddenly become painful and itchy. 
Her grandparents rushed her to a nearby Red Cross 
stand. "I'm a little afraid to go back in the 
water," she said, displaying a row of angry red 
welts on her shin.

Francisco Antonio Padrós, a 77-year-old 
fisherman, swore mightily as he unloaded his 
catch one morning last weekend, pulling off 
dozens of jellyfish clinging to his nets and 
tossing them onto a dock. Removing a few shrimp, 
he said his nets were often "filled with more 
jellyfish than fish."

By the end of the exercise his calloused hands 
were bright red and swollen to twice their normal 
size. "Right now I can't tell if I have hands or 
not - they hurt, they're numb, they itch," he 
said.

Dr. Santiago Nogué, head of the toxicology unit 
at the largest hospital here, said that although 
90 percent of stings healed in a week or two, 
many people's still hurt and itched for months. 
He said he was now seeing 20 patients a year 
whose symptoms did not respond to any treatment 
at all, sometimes requiring surgery to remove the 
affected area.

The sea, however, has long been central to life 
in Barcelona, and that is unlikely to change. 
Recently when the beaches were closed, children 
on a breakwater collected jellyfish in a bucket. 
The next day, Antonio López, a diver, emerged 
from the water. "There are more every year - we 
saw hundreds offshore today," he said. "You just 
have to learn how to handle the stings."