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Abnormally large number of dead salp colonies attracted to Malta’s sea

Besides the ubiquitous and dreaded mauve stinger (Pelagia noctiluca), numerous other groups of gelatinous plankton have appeared in the Maltese Islands.

16 April 2013, 12:00am
Velella at Fomm ir-Rih (pic: Adrian Mallia)
Velella at Fomm ir-Rih (pic: Adrian Mallia)

On land, spring is invariably associated with blooming flower beds and teeming insect life. Yet, concomitantly, spring time also brings about a watershed of diversity in terms of gelatinous plankton on our seas.

In fact, besides the ubiquitous and dreaded mauve stinger (Pelagia noctiluca), which is present in our waters for most of the year (except during the October-December period), numerous other groups of gelatinous plankton have appeared in the Maltese Islands. These include an abnormally large number of dead salp colonies, which are mostly transparent and resemble plastic bags.

Salps are much more complex than 'jellyfish', being pelagic tunicates and having a primitive brain and even segmented muscles. An individual of Portuguese man 'o war, or blue bottle (Physalia physalis), was also observed earlier this week at Spinola Bay.

This siphonophore species is actually a colony attached to a gas-filled floating sac known as a pneumatophore, of Atlantic origin, which occasionally reaches also our waters. Also very abundant in our waters at the moment is another floating colony - the innocuous, bluish by-the-wind sailor (Velella velella).

The Spot the Jellyfish team will be affixing the beachside informative boards in the coming weeks and the 2013 version of the campaign leaflet has been distributed amongst all local diving clubs and local councils.

 Other initiatives being taken include the development of an ad hoc smart phone application to enable the public to record the occurrence of jellyfish in real time from any bay in the Maltese Islands, allowing bathers to know beforehand where jellyfish are being recorded.

Besides the indigenous jellyfish species, one should also look out for the non-indigenous ones which have spiraled in numbers in recent years. In fact, at least 11 non-indigenous jellyfish species are known from the Mediterranean, most of which have entered the Basin through the Suez Canal, such as the nomadic jellyfish Rhopilema nomadica, the Australian spotted jellyfish Phyllorhiza punctata, the upside down jellyfish Cassiopea andromeda and, most recently, Marivagia stellata.

The Spot the Jellyfish initiative is coordinated by Dr. Alan Deidun, Prof. Aldo Drago, Dr. Joel Azzopardi, Mr. Adam Gauci and Mr. Martin Galea Degiovanni, and enjoys the support of the Malta Tourism Authority (MTA) and of Nature Trust, Friends of the Earth, EkoSkola, the BlueFlag Malta programme and Sharklab.

The reporting is done by simply matching the sighted jellyfish with a simple visual identification guide, giving the date and time of the sighting, and indicating the number of jellies seen. Sightings can be also reported online (, or submitted through an SMS on 79604109, or by sending an email message to [email protected].

Strange jellyfish not included on the leaflet should be caught and kept in a bucketful of seawater prior to contacting IOI-MOC staff for retrieval to attempt a definite identification of the species. So far, well over 1000 reports by the public have received, since June 2010, for a total of 16 different species of gelatinous plankton.