Hundreds of upside-down jellyfish have bloomed in the shallow waters near Salina over the past few days for the first time in nearly a decade. The jellyfish Cassiopea andromeda is an alien species that entered the Mediterranean after the opening of the Suez Canal and was first recorded in Malta in 1886.
Professer Alan Deidun told Lovin Malta that the species “comes from topical waters like the Red Sea, and thrives in warm waters. It was one of the first aliens to come through the Suez Canal to the Mediterranean.”
Prof Deidun said that it mainly restricted itself to the eastern Mediterranean, but how now been spotted in the central area.
The late marine biologist Patrick Vella first recorded this species in Malta in 2009, in Marsamxett Harbour, which, Prof Deidun pointed out, is a very similar habitat to Salina.
“Salina has three meter shallow waters, a sandy bottom, and is sheltered,” he said, providing the three needed conditions for the upside-down jellyfish to live in.
“It likes to stay on the seabed with its umbrella against the seabed and its tentacles pointing upwards towards the sun,” he said. The purple tips of the tentacles are actually microscopic algae that act like miniature solar panels, and that’s why it needs shallow waters, to be able to reach the sun.
As scary as the jellyfish looks, Prof Deideun said it actually has a “very mild sting which is not even perceived by most people.”
Prof Deideun commented that, following finds of species like the white stopped Australian jellyfish in 2017, “Salina seems to be a hotspot for aliens. My hunch is that Salina is a living laboratory, because it has the right ingredients, shelter, the water is normally warmer, and its saltier, so for these guys coming from tropical waters it is crucial.”
Asked whether the latest bloom of alien jellyfish will leave any impact, he said “this is a bloom, it shouldn’t go unnoticed, because a bloom will effect the ecosystem over there, so there will be some sort of ecological impact. It depends on how long the bloom will last, if it lasts for weeks, and if it starts happening every year,” he said.
The jellyfish was spotted after a report to Spot the Jellyfish, which Professor Deidun coordinates.