Long term (1981-2008) monitoring of the jellyfish Pelagia noctiluca (Cnidaria, Scyphozoa) on the French Mediterranean Coasts

In the early 1980s, a large proliferation of the jellyfish Pelagia noctiluca in the Mediterranean drew the attention of governments, the general public and scientists. Its unpleasant and dangerous sting has had an indirect effect on tourism and its proliferation has also interfered in coastal dragnet fishing. In France, this abnormal abundance prompted the implementation of a national monitoring program. During the summer months, on major beaches, forms were given to lifeguards to report, on a daily basis, the approximate abundance of jellyfish and the number of first-aid given to bathers stung by jellyfish. This French Mediterranean Jellyfish Monitoring Network, set up by Patrice Bernard, was done under the aegis of INSERM by the lifeguards (Maitres Nageurs Sauveteurs) of the French Police (1984-1998), the Surete of Monaco (1981-2008) and the Firemen of the city of Nice (1995-2008). Here we present annually aggregated results of the monitoring from 1981 to 2008, for a subset of beaches located in the French Riviera from Monaco to Cannes. The number of first aid given is used as a proxy of the abundance of Pelagia. Over the period, Pelagia bloomed from 1981 to 1985. Then only a few Pelagia were reported, until another proliferation lasting about 15 years from 1994 to 2008, except during 1997, 2001 and 2002 that had very low abundance. At the scale of the Ligurian region, these results confirm years of presence and quasi absence of Pelagia, and the peculiarity of the last period with long lasting abundance.