CIESM JellyWatch Program: Monitoring jellyfish swarms along Mediterranean coastlines and in the open sea.

Jellyfish have always inhabited the Mediterranean Sea, but “jelly blooms” were rare episodes until the last eight years when massive swarms of gelatinous organisms have become a frequent sight in coastal waters. Such events represent undoubtedly a nuisance for people, and in some cases they become a real health hazard. 

They are considered a pest by fishermen, as they clog nets and keep away fish. More recently, an increasing number of industrial marine cooling systems have been put temporarily out of order by jellies filling out the underwater pipes. The resulting socio-economic impacts – both direct (tourism) and indirect (coastal development, fisheries) – are thus tangible. The apparent increase and synchrony of jellyfish outbreaks in both western and eastern basins sends an alarming ecological signal of a potential ecosystem shift towards a “gelatinous sea” to the detriment of fish species. Although overfishing and climate warming are amongst the most probable drivers, the specific causes and mechanisms are not well identified, and the lack of reference data makes any further investigation difficult.

The new CIESM Jelly Watch Programme shall gather for the first time baseline data on the frequency and extent of jellyfish outbreaks across the Mediterranean Sea. After the initial phase involving a few countries, a common, standardized protocol will be adopted for both coastal and open sea sightings of jellyfish swarms in the whole Basin, enabling an unbiased assessment of the geographic and temporal scale of these mass events. Offshore observations will be taken aboard vessels of opportunity (ferries, coastguard boats) along selected Mediterranean routes cutting across the different sub-basins. Records will be related to both field (see CIESM TransMed Programme) and satellite hydrological data (salinity, temperature and currents).

In summer 2008, JellyWatch did start with a launch of a pilot, citizen-based study: a poster has been produced to draw the attention of coastal users (fishermen, divers, tourists) but also ferry passengers, asking for their report of sightings of jellyfish swarms. In the poster detailed drawings illustrate species of jellyfish most commonly found in the Mediterranean along with a list of basic questions (formulated for the non-specialist observer) on the location, type and extension of the observed swarms. Records are sent by email to key scientists who act as focal points in different regions. After accurate screening and validation of the records, data will be centralized and integrated in the CIESM Metabase. 

The poster has been translated in different languages to maximise public awareness of the issue and stimulate Citizens participation in the JellyWatch Programme. The poster is being tested in Italy (with the support of CoNISMa and MARE VIVO) and will be soon distributed in Croatia and Israel.


National JellyWatch Focal Points:
Croatia - Adam Benovic, University of Zagreb
Israel - Bella Galil, IOLR
Italy - Ferdinando Boero, Univ. del Salento