Swarms of venomous jellyfish move towards British waters

[Savwafair2012 Profile]

Swarms of highly venomous jellyfish which can devastate fish farms are moving into waters off the British coast, according to experts



The lethal mauve stingers - Pelagia noctiluca in Latin - are tiny but can cover hundreds of thousands of square miles in one "bloom".

They are normally found in the Mediterranean and Caribbean.

But billions of them are swarming far more frequently into waters in the north east Atlantic as sea temperatures are rising and currents are changing, scientists have discovered.

These venomous creatures can devastate fish farms and in one recent incident 100,000 salmon were killed.

Mauve stingers "bloom" when they move into waters where there is plentiful food, and the north east Atlantic has bountiful supplies of plankton and young fish.

They are also thought to breed more quickly in warmer waters and the seas off the British coast have warmed by up to 1C since 2002.

Experts researching plankton discovered the movement towards British waters, according to a study published in the journal Biology Letters.

The trend may continue if climate change follows the predictions of the Intergovernmental Panel on Climate Change.

While people bathing in the waters off the UK coast are in no serious danger yet from the Pelagia noctiluca, fish farms and other businesses could be affected.

The study was led by Dr Priscilla Licando at the Sir Alister Hardy Foundation for Ocean Science, and Dr Richard Kirby, a Royal Society Research Fellow at the University of Plymouth.

Dr Kirby said: "By studying plankton samples we have shown that the warm-water jellyfish called Pelagia noctiluca appears to be the main species present in our samples when large blooms of jellyfish occur in the north east Atlantic.

"We believe that an increase in sea temperature is likely to influence jellyfish abundance by affecting their reproduction.

"It is already known that Pelagia noctiluca and similar jellyfish reproduce more quickly in warmer waters. Predictions of global climate change suggest that the seas around our coasts will continue to warm.

"Climate driven changes in sea surface currents could carry more Pelagia noctiluca into coastal seas where food resources are higher, promoting jellyfish blooms.

"Jellyfish are important predators in the plankton where they can influence the number of juvenile fish that survive to become adults.

"Since Pelagia noctiluca is also a highly venomous species it can be detrimental to fish farms by killing large numbers of fish when it reaches high densities.

"They can also make bathing waters dangerous, but that is more of an issue in the Mediterranean at present."

The mauve stinger uses its sting to capture food and as a way of defending themselves.

They can cause painful stings to bathers but are lethal to larger fish when they move in great numbers.

In 2007 an enormous 10 square mile swarm of billions of the jellyfish wiped out a 100,000-fish salmon farm in Northern Ireland, causing around £1m in damages.

http://www.telegraph.co.uk/earth/earthn ... aters.html