A jellyfish bloom was observed yesterday along the northern coast of Gozo, in a further sign that the Mediterranean Sea is on an unremitting warming trend.

Marine biologist Alan Deidun said the bloom consisted of thousands of mature mauve stinger (Pelagia noctiluca).

Blooms for this species normally commence towards late autumn in the warmer waters off North Africa, making their appearance further north in Maltese waters towards mid-winter (February).

"Thus, their anticipated occurrence this year could be indicative of the inexorable warming of the Mediterranean Sea, which has warmed up by as much as 0.5 degrees centigrade since 2002 (at least in the western half of the basin)," Dr Deidun said.

The mauvie stinger is a highly versatile species, being able to tolerate sea temperatures ranging from 8 to 22 degrees, delaying release of ephyrae (miniature jellyfish) until optimum environmental conditions are found. It has wide distribution, even in the Atlantic Ocean.

Until 1998, Pelagia blooms occurred every 12 years and had an average duration of four years – since they, they have become more common, presumably as a result of the stressed status of the Mediterranean, due to climate change, overfishing and coastal urbanisation and discharges.

Dr Deidun is a lecturer at the IOI-MOC of the University of Malta and he is currently investigating the dynamics of jellyfish blooms in Maltese waters. The institute conducted an intensive jellyfish spotting campaign this year – Spot the Jellyfish – which is set to continue again throughout 2011. Jellyfish sightings can be reported online at www.ioikids.net/jellyfsh or submitted through an SMS on 79 222 278, or by sending an email message to ioi-moc@um.edu.mt.