Too many medusae

[Guest guest]

Published on August 8, 2006 by the Independent / UK

 

Jellyfish Plague Blamed on Climate Change

by Stephen Castle

 

 

A plague of jellyfish along Europe's beaches has

become the latest environmental hazard to be blamed on

global warming.

 

Holidaymakers heading for Mediterranean beaches are

being warned to prepare for an unprecedented invasion

of the invertebrates whose sting can, in extreme

cases, cause heart failure.

 

Oceana, which campaigns to protect and restore the

world's oceans, attributes the rise in the number of

jellyfish to a rise in water temperature because of

climate change. It also highlights over-fishing of

natural predators that feed on jellyfish, and

pollution along the continent's coasts.

 

The group sent a research boat around Spain's coastal

waters last month and concluded that many beaches are

suffering an " invasion by this species " .

 

After navigating the waters of the Mar Menor, Ricardo

Aguilar, the director of research on Oceana's

catamaran, said: " We have found jellyfish all over the

Mediterranean, but in this area we've seen

concentrations of more than 10 jellyfish per square

metre. Wherever we look, there is practically nowhere

without jellyfish. "

 

Among the most notorious of jellyfish is the

Portuguese man of war (Physalia physalis), whose

stings can produce painful burns for bathers, and have

even led to heart failure.

 

The Spanish researchers highlighted the prevalence of

the purple jellyfish or mauve stinger (Pelagia

noctiluca), whose stings can provoke severe swelling,

burning pain and allergic reactions.

 

Other scientists have noticed the growing numbers of

jellyfish. Gianluca Sara, the assistant professor of

ecology and marine biology at the University of

Palermo, plans to launch a research project on the

issue in the autumn.

 

Dr Sara said: " I have no scientific data but, as an

observer, there seems to be a huge increase along the

Sicilian coast. I feel that temperature increase and

over-fishing are related to this though, at the

moment, this is only my feeling. "

 

Jellyfish spend most of their lives in the open seas,

because that is where the water tends to be more

saline and warmer.

 

However, researchers believe they approach beaches

when water near the coast, which is generally colder

and less saline, stops acting as a barrier. That has

happened in many places as there is less freshwater

entering the sea from rivers because of the drought.

 

Oceana also blames the industrialised nature of modern

fishing for reducing the number of predators that

normally feed on jellyfish and keep their population

under control.

 

Sometimes deliberately, sometimes accidentally through

by-catches, fisherman have caught tuna, swordfish,

moonfish, triggerfish and certain kinds of sea turtles

- especially the leatherback turtle (Dermochelys

coriacea), which is a major jellyfish predator.

 

Another cause of the invasion of the invertebrates may

be the increase in nutrients in seawater due to

contamination from land. Changing ocean tides could

also be instrumental.

 

Advice from Oceana for those who are stung by

jellyfish is to avoid rubbing the affected area with

sand or with a towel. It says that freshwater should

not be applied to the sting as the change in salinity

could cause the stinging cells to burst and liberate

the poison. It recommends using an ice pack in a

plastic bag to avoid direct contact with the skin,

unless the ice is made from seawater.

 

© 2006 Independent News and Media Limited

 

###

 

Stupid Question ™

 

June 7, 2004

 

By John Ruch

 

© 2004

 

 

 

Q: Is it true that urinating on a jellyfish sting

alleviates the discomfort? If so, who figured that

out?

 

—Anonymous, from the Internet

 

 

A: At best, urinating on a jellyfish sting will do

nothing. Experiments indicate that in some jellyfish

species, urine actually sets off the remaining

stinging cells, making the sting even worse.

 

The urine cure and other folk remedies

miss the mark, anyway. The point of rinsing the

wounded area is not to alleviate the pain. The venom’s

already in you. Urinating on it will not help any more

than it does to urinate on your thumb after you hit it

with a hammer.

 

The point of the rinse is to get rid of

any remaining tentacles or other jellyfish tissue that

might still harbor stinging cells, or nematocysts,

which could still fire and make the sting worse.

(These cells, which are all over jellyfish, contain a

tiny poison dart that shoots out at a touch or because

of a chemical reaction; thousands of them typically

fire simultaneously.) For the aforementioned reason,

urine is a terrible candidate for the job.

 

Susan Scott, “Oceanwatch” columnist for

the Honolulu Star-Bulletin, has investigated jellyfish

stings in the field (as well as in the lab) probably

as much as anyone, having spent years visiting injured

tourists and the like on Hawaii’s beaches. A

registered nurse, she and husband Dr. Craig Thomas

authored “All Stings Considered: First Aid and Medical

Treatment of Hawai’i’s Marine Injuries.”

 

In her column in 2001, Scott summed up

years of study on a variety of sting “cures”: “Nothing

worked.” In an e-mail to me, she summed it up another

way: “Anything works.”

 

This paradox goes to the heart of the

urine myth. “Nothing worked” means that none of the

main folk remedies—including urine, meat tenderizer

and commercial sprays—did anything to stop the pain of

a sting.

 

On the other hand, “Anything works,”

because the vast majority of jellyfish stings are not

severe and their effects disappear within a few hours

at most, no matter whether you urinate on yourself or

simply do nothing.

 

“Anything works for another reason”—mind

over matter. “The placebo effect is a powerful

treatment,” Scott said, referring to the common

psychological phenomenon in which people who receive a

useless treatment feel better simply because they

think they have been medicated. In this case,

believing you have been given an analgesic may well

reduce your subjective experience of pain. (In

addition, different people can have widely varying

pain thresholds.)

 

Folk remedies for jellyfish stings can be

quite exotic; Scott mentioned mustard, and minor

studies have been done on Coca-Cola. But the urine

cure is exceptionally widespread, found on beaches

from Vietnam to Belize. It is also applied (equally

uselessly) to other marine wounds, like coral cuts and

sea urchin spike punctures. How did the idea get

started?

 

Urine is an ancient folk medicine for a

boggling variety of ills, and its main nitrous

component, urea, does have some real medicinal

properties (though not for jellyfish stings). Among

many other things, it’s also a folk remedy for bee

stings.

 

Scott had a simple conjecture for its

application to jellyfish: “We think this is because

it’s usually the only substance readily handy during

jellyfish stings.”

 

The “anything/nothing works” warning

aside, there are definitely things you should do to

treat a jellyfish sting, and there are things you can

do to prevent it from becoming worse. (The following

information focuses on box jellies and Portuguese

man-of-wars, which are the most dangerous jellyfish on

bathing beaches; check with lifeguards at your beach

for guidance on identifying local dangerous species.)

 

In all cases, immediately scrape off any

remaining tentacles or other visible jellyfish tissue

with a glove or some kind of tool—never with bare

hands.

 

On box jellies, you can rinse the area

with vinegar. Experiments have shown that vinegar

chemically deactivates the nematocysts of box jellies,

disabling any remaining cells from firing into your

skin.

 

On Portuguese man-of-war stings, do not

use vinegar; experiments show that in its species,

vinegar sets off the nematocysts. Instead, just rinse

the area with seawater. (Fresh water is probably OK,

too, though some doctors worry it can also set off

nematocysts by osmosis.)

 

Once the area is clear of any more

nematocysts, you can attempt to deal with the pain.

Gritting your teeth works. Scott said hot or cold

packs, or hot baths, are the only treatments she’s

seen work for anybody.

 

If the pain is severe and lasting, or

there are any other symptoms such as sweating or

faintness, go to an emergency room immediately. Some

jellyfish are certainly capable of killing humans, and

some people are highly allergic to minor stings.

 

If you touched the area with your hands

before rinsing, make sure you wash up before touching

yourself anywhere else, especially your eyes. An

eyeful of nematocysts is unpleasant indeed.