BIOLOGISTS are warning bathers that the plague of jellyfish which has accompanied the onset of summer in recent years is likely to be just around the corner, and this year they might be joined by new, more menacing varieties.
“The poor winter rains and hot summers, which are becoming more pronounced due to climate change, are one of the main causes of the jellyfish proliferation,” says Veronica Fuentes, a researcher at the Barcelona Institute of Marine Sciences. “Factors which provoke large jellyfish accumulations vary depending on species, but include rising temperatures, increased nutrients in the water, and others, so there is no single key influence.”
The most frequently-cited pests along Spain’s Mediterranean coastline are the mauve stinger, Pelagia noctiluca, and the Portugese man o’war, Physalia physalis, although the latter is not a jellyfish but a but a colonial siphonophore made up of minute individual animals called zooids.
Although the former is currently more common and not particularly dangerous, the man o’war is on the increase in the Spanish Med, and with tentacles up to 50 metres long an encounter with a human swimmer can even prove fatal.
A third species, the Indo-Pacific nomad jellyfish, Rhopilema nomadica, may appear any time now since it has entered the Mediterranean via the Suez Canal, with numerous sightings in Israel in recent years.
It can grow to a weight of 10 kilos and is capable of delivering an extremely painful sting, while it is able to reproduce so quickly that experts predict it will soon spread throughout the Med.
In Cataluña and the Balearics, specialised management plans are afoot, with prototypes of the MED-JELLYRISK anti-jellyfish nets being trialed following their successful deployment in Italy.
Costa del Sol bathers may be spared the wobbly epidemic entirely this year, though, since the spring jellyfish bloom has not materialised as yet, with biologists believing that the rains which swept the region in late spring have kept them away from coastal areas due to the influx of fresh water from rivers.
This theory is not yet proven, but spokesman for the Aula de Mar museum in Malaga city, Juan Jesus Martin, said: “It is not an exact science, but a dry winter and spring tend to favour jellyfish.”
Jellyfish swarms tend to appear for periods of two to three days several times during the summer period, but Martin and his team suspect that they might not show up at all due to the natural barrier of decreased salinity brought about by the heavy rainfall.