Thousands of jellyfish beached along Malta's coastline

Persistent south-easterly winds leave thousands of jellyfish beached along stretches of Malta and Gozo's coasts

Massive beaching of adult mauve stinger individuals at Pretty Bay, Birzebbuga, following persistent south-east winds in recent days (Photos: Cleansing and Maintenance Department)
Massive beaching of adult mauve stinger individuals at Pretty Bay, Birzebbuga, following persistent south-east winds in recent days (Photos: Cleansing and Maintenance Department)

Thousands of jellyfish have been spotted along Malta's beaches in the past week weeks, as winds from the south-east push the creatures to shore.

Especially noticeable have been the reports of the mauve stinger (Pelagia noctiluca) bloom, which has been reported to the Spot the Jellyfish team over the past few days by several members of the public along several stretches of the coast of Malta and Gozo.

The jellyfish have been sighted especially in south-eastern and eastern swathes of the coastline, where persistent south-easterly winds have resulted in a massive beaching of thousands of mature mauve stinger individuals, said marine biologist Alan Deidun from Spot the Jellyfish, the citizen science campaign which will celebrate its tenth anniversary in June.

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 mid-winter (late January and early February), Deidun said.

"At this time of year, in fact, mature mauve stingers rise to the upper waters from deeper ones to reproduce, before dying en masse. This bloom coincides with the annual phytoplankton bloom which is witnessed in the central Mediterranean at this time of year, with the new generation of ephyrae (miniature jellyfish) making their appearance in a few months’ time (mid-spring)," he said.

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.

In fact, until 1998, mauve stinger blooms occurred every 12 years and had an average duration of four years – since they, they have become more common, presumably as a result of the stressed status of the Mediterranean, presumably due to climate change, overfishing and coastal urbanisation and discharges.

Also being spotted in significant numbers this winter are the comb jellies (Ctenophora).

"These fascinating creatures have also arrived to our upper sunlit waters to feed on the planktonic blooms typical for this time of year; and unlike the unrelated mauve stingers, these gentle animals do not sting or harm humans. In fact, some of these comb jellies have the rare and fascinating ability to be able to emit their own light, and often delight divers with their underwater sparkles. The by-the-wind sailor will soon make its first appearance in local waters, as this species is normally expected to appear in early spring," Deidun highlighted.

Since the inception of the Spot the Jellyfish campaign, the public has submitted thousands of jellyfish reports, which are assessed from a scientific/technical perspective so as to identify trends and links with environmental parameters and are also being plotted on map of the Maltese Islands for the benefit of all sea users.

Nine new jellyfish species, previously unknown from Maltese waters, including the nomadic jellyfish, crystal jellyfish, and compass jellyfish, have been recorded since the start of the same campaign, bringing the total number of gelatinous species known from Maltese waters to date to over 40.

The Spot the Jellyfish campaign has been led since 2010 by the Physical Oceanography Research Group based within the Department of Geosciences at the University of Malta.

It is set to continue throughout 2020, and is coordinated by Deidun, Prof. Aldo Drago, Adam Gauci, Martin Galea Degiovanni, Joel Azzopardi and Johann Galdies.

Reporting can be done online through by matching the sighted jellyfish with a simple visual identification guide, giving the date and time of the sighting, and indicating the number of individuals seen.

Sightings can also be reported by text message to 7960 4109 or by emailing [email protected].

Strange-looking jellyfish that are not included on the leaflet should be caught and kept in a bucketful of seawater prior to contacting Deidun on e-mail ([email protected]) or the PO Unit on 2340 2844 to collect for definite identification of the species.

If this is not possible, photos of the jellyfish should be taken and sent to the PO Unit’s offices at the University of Malta.

All submitted reports can be viewed online on a summary map which depicts jellyfish occurrence and distribution on a spatial and temporal scale. The campaign is supported by the Malta Tourism Authority (MTA), Nature Trust (Malta), the EkoSkola network, BlueFlag, Friends of the Earth and Sharklab.

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