A mauve stinger jellyfish bloom has been reported to the Spot the Jellyfish team over the past few days along stretches of the north-western and north-eastern coasts of Malta and Gozo.
The university team said the bloom consists of thousands of mature mauve stinger (Pelagia noctiluca) individuals. At this time of year mature mauve stinger individuals rise to shallow waters from deeper ones to reproduce, before dying en masse.
Blooms for this species are typical for this time of year in the Central Mediterranean, normally commencing towards late autumn in the warmer waters off north Africa, making their appearance further north in Maltese waters towards early and mid-winter (late December till early February).
The mauve stinger has been observed in the Mediterranean at least since 1785, but outbreaks of the species have become more frequent only since 1999.
Until 1998, Pelagia blooms occurred every 12 years and had an average duration of four years. They have since become more common, ppossibly as a result of the stressed status of the Mediterranean, due to climate change, overfishing and coastal urbanisation and discharges, the Spot the Jellyfish team said. Abnormally-large mauve stingers, having a diameter exceeding 15cm in many cases, were witnessed at this time last year.
The mauvie stinger is a highly versatile species, being able to tolerate sea temperatures ranging from 8 to 22 degrees, delaying release of ephyrae (miniature jellyfish) until optimum environmental conditions are found. It has a wide distribution, even in the Atlantic Ocean.. The abundance of the species is affected by low rainfall, high temperature and high atmospheric pressure. A recent study, conducted in the Straits of Messina, has concluded that increasing sea temperatures in the Mediterranean will result invariably in more frequent blooming events for the species in future.
The Spot the Jellyfish campaign has been conducted since 2010 by the IOI-Malta Operational Centre based at the University of Malta, a campaign which is set to ensue during 2014. It is led by Alan Deidun, Prof. Aldo Drago and Martin Galea Degiovanni.
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