It's that time of the year again, when, with the soaring temperatures and the bathing season on the horizon, public and media attention on jellyfish reaches feverish levels. But behind the hype, concrete initiatives are being embarked upon this summer to closely monitor jellyfish blooms.

When occurring in isolation, individual jellyfish represent more of an intriguing attraction to bathers than a source of consternation. In fact, most top-notch aquariums nowadays regularly feature jellyfish in their collections, using what is known as a kreisel (German for spin, carousel) which creates a continuous current to avoid the jellyfish piling up on the sides of the tank.

It is the dense jellyfish aggregations, aptly dubbed swarms or blooms, that hog the headlines. How do such swarms come about? Several hypotheses have been floated around in an attempt to explain this mind-boggling phenomenon, including some of the most esoteric and unlikely of explanations.

Most marine researchers concur that jellyfish booms occur due to the rise in sea temperatures and because of marine ecosystems being overstressed by human activity, such as through overfishing and the overloading of nutrients caused, for example, by nitrates and phosphates used in fertilisers being discharged into the sea by rainwater runoff, rivers, or from fish-farms.

Two common myths about jellyfish are constantly perpetuated. The first is that jellyfish blooms are a recent phenomenon. Although it is true that the frequency of such blooms has increased in recent times, records of blooms of the mauve stinger (Pelagia noctiluca) on the French Riviera date way back as early as the 18th century.

In 1983, Prof. Victor Axiak reported that aggregations of the purple-striped jellyfish from local waters occurred during the 1958-1960 period.

Researcher Guido Lanfranco reported unusually large numbers of the fried egg jellyfish in local bays and harbours facing the south and southeast, from mid-August to mid-September 1977.

Researcher Edwin Lanfranco reported large swarms of the purple-striped jellyfish in local waters in the summer of 1981.

The second myth is that the larger the jellyfish the more painful its sting. In reality, while the dinner-plate-sized fried egg jellyfish is quite harmless, the much smaller sea-wasp can inflict particularly excruciating stings. Last year, the Mediterranean Science Commission (CIESM) launched a pilot project in Italy aptly called Jellywatch (www.ciesm.org/marine/programs/jellywatch.htm). The initiative entailed the production of posters, clearly depicting the most common jellyfish species occurring in the Mediterranean, and disseminating it among the general public as widely as possible, including to schoolchildren, divers, beach-users, boat owners, and fishermen.

Upon sighting a jellyfish bloom, people were asked to submit a record through e-mail. No special prowess is needed to scientifically identify and classify the species as the jellyfish figures in the poster are easily distinguishable.

The ultimate aim of the project is to build a database of jellyfish swarms across the Mediterranean, in preparation for a fully-fledged scientific monitoring programme to kick off in the next few years. The Monterey Bay aquarium hosts a similar online database (see www.jellywatch.org).

As with other groups of marine organisms, 'alien' or 'exotic' jellyfish species are colonising Mediterranean waters and the aim of the Jellywatch programme is also to monitor the spread of these alien jellyfish.

Most of these species are of tropical Indo-Pacific origin, native of warmer seas, having entered through the Suez Canal, and their spreading to our sea might indicate a general warming of the Mediterranean.

Such species include the nomadic jellyfish which forced an electric power plant in Israel to shut down in the summer of 2001 after clogging its cooling water intake screens.

They also include the upside-down jellyfish which harbour light-harvesting microorganisms in its tentacles and which recently has reached our shores too.

The Jellywatch project is essentially a 'citizen science' initiative, which seeks to engage the public to provide scientific data.

Citizen science approaches are feasible and cost-effective ways of acquiring scientific data over a wide area, while concurrently serving to educate the public engaged in such initiatives.

The first citizen science initiative was the Audobon Society's Christmas Bird Count, which started being conducted way back in 1900 and is still ongoing, involving almost 53,000 members of the public in 17 different countries in 2001.

An adaptation of the CIESM Jellywatch poster has been produced by the International Ocean Institute Malta Operational Centre at the University of Malta as part of its ongoing IOI-Kids programme (www.ioikids.net/jellyfish), as part of a 'Spot the Jellyfish' programme.

Since the poster is mainly aimed at schoolchildren it includes fewer jellyfish species than the CIESM poster and has a more child-friendly format.

This is the second local initiative of its kind. In 1982, Malta had taken part in the MEDPOL Jellyfish Monitoring Programme, which entailed the recruitment of a large number of volunteers, owners of touristic establishments, beach cleaning workers and even the Maritime Squadron of the Armed Forces of Malta.

The study had reported that the highest accumulations of jellyfish occurred in the southeast coastal areas of Malta and Gozo, presumably as a result of the prevailing northwesterly winds.

It is intriguing that the study had concluded that between 1980 and 1983, highest densities of P. noctiluca species were reported during the summer months, while in subsequent years, the highest densities were reported during the months of March and April.

So keep your eyes peeled this summer and keep those jellyfish records rolling in. You don't need to get stung to file a report, and sending photos, albeit not mandatory, could help supplement jellyfish records.

Jellyfish snippets

• People in China have been eating jellyfish since 320 AD, and almost half a million tons of the gelatinous fish is consumed every year in southeast Asia.

• Jellyfish fisheries exists in 15 countries, including China, Japan, India, Indonesia and the Philippines, with export industries present even in Australia and the US. It is very ironic that while fisheries of numerous fish species, such as cod, bluefin tuna, and anchovies, are collapsing around the globe, jellyfish fisheries are in their prime.

• The largest individual jellyfish ever recorded had tentacles that stretched for a total of 120 feet, a length greater than that of the blue whale. It washed up on the shore of Massachusetts Bay in 1870.

• As the world's top marine predators, namely sharks and bluefin tuna, are inexorably being decimated, jellyfish are slowly taking over as the top predators of the seas, bolstered by their amazing increase in numbers over short time spans. As originally coined by marine researcher Ferdinand Boero, we are witnessing a 'fish to jellyfish' shift in the Mediterranean.

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