4 June 2013

Jellyfish swarms threat to fish and swimmers in the Mediterranean

Scientist have reported large jellyfish blooms across the Mediterranean - bad news to tourists and fish stocks and it could be the new norm.

Scientists warn of a surge in the numbers of "mauve stinger” (Pelargia noctiluca) jellyfish this spring threatening fish stocks and summer tourists across the Mediterranean.

Josep Maria Gili, jellyfish researcher at the Institute of Marine Sciences in Barcelona said: "It is a growing problem in the Mediterranean, as it is in the rest of the world.”

"We have seen banks several kilometres long and with a density of 30-40 jellyfish per square metre” adding "The ones we have found this spring are particularly big. Normally, that size of jellyfish does not reach the coast because of the temperature of the water.”

A report produced the Food and Agriculture Organization of the UN links global overfishing to an increase in jellyfish blooms. Fish larvae compete with jellyfish for the same food, if the adult fish populations are healthy the large numbers of larvae and juvenile fish can out compete the jellyfish. Sparser populations of fish release jellyfish from their competition and the jellyfish also eat the fish larvae.

Apart from staying out of the water, which you probably would if a swarm of jellyfish arrive, barrier methods seem the best prevention. Jellyfish stings "fire” on contact with the skin so a wetsuit or swimsuit can help. Sunscreen can also help, both by stopping the sting mechanism from recognising it is against your skin but some have been developed with chemicals that suppress the stingers firing mechanism.

If you are stung by a mauve stinger, don't rub the area – the stingers break off and attach themselves to your skin, the rubbing action will cause more stingers to fire. Experts recommend washing with salt water or (better) vinegar. Next cover the area with sunscreen and scrape off any remaining stings using a credit card. This is simply to stop getting any more venom into your system. A paste of baking soda and water can be applied to the skin to neutralise the poison and antihistamine pills will damp down skin reactions.

If you are unfortunate enough to need medical attention, you will be glad to have sorted your travel insurance before your holiday.