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.
EDIT
http://www.ecoearth.info/articles/reader.asp?linkid=59252