Purple jellyfish, or Pelagia noctiluca, as they are scientifically known, are found in the Greek seas this year as they are on the rise. They are mainly found in the Aegean and Ionian Seas.
Purple jellyfish are considered one of the most dangerous jellyfish species in the Mediterranean and we may have them for another 2 years or so. They reappeared in the Greek seas in October 2020.
Their sting is painful due to their neurotoxin, so bathers should be well informed about what to do in case of a sting.The population boom of purple jellyfish in an area was observed before climate change about every 10 to 12 years and lasted a maximum of 4 years (with an average of 2-3 years). In 2015 until 2018 there was a strong population boom of this species in the Gulf of Corinth, in Malta from 2018 to 2020, and we saw a re-emergence in Malta and in January 2022.
This year, they have been observed in several areas of the Aegean and the Ionian Sea, and winter swimmers reported seeing this species of jellyfish in winter as well. However, their presence is greatly increased in summer as breeding conditions are favoured due to higher sea temperatures. Their reproduction is also favoured by climate change which increases the water temperature.
The reasons favouring their spread
At the same time, the decrease in the population of fish, which are their predators, and the decrease in the populations of sea turtles, which are their main predators, favour the spread of jellyfish. The purple jellyfish is a pelagic species and lives in tropical waters. It has a maximum length of 10 cm in diameter and the length of its tentacles can reach up to 10 m. It mainly feeds on salps, various tunicates, planktonic crustaceans and fish eggs. The largest natural predators of jellyfish are leatherback turtle, caretta caretta, tuna, swordfish and moonfish. When young, its colour is orange-brown and when it becomes an adult it takes on a bright purple-purple colour.
Identification is by its external morphological characteristics, i.e. what colour it is, whether it has spots or stripes on its bell, whether its gonads are visible and what shape they are (for transparent jellyfish, e.g. Aurelia sp.), how their tentacles are shaped and whether they have different colours or stripes on their tentacles or bell.
"Each species of jellyfish has a natural boom every few years. e.g. the Mediterranean jellyfish (Cotylorhiza tuberculata) has a boom every year in August, while the jellyfish pyx (Chrysaora hysoscella) has a boom every year from March to mid-May. The purple jellyfish (Pelagia noctiluca) had a natural outbreak every 8 to 10 years and their outbreaks lasted up to 4 years maximum. But due to some factors such as climate change, overfishing, lack of predators, etc. has helped these outbreaks to become more frequent and more widespread," Christos Taclis, who is a Marine and Conservation Biologist and Administrator of the Hellenic Biodiversity Observatory, explains to APE-MPA. Almost all jellyfish species are found in deep water and away from beaches. But because their movement is passive as they are carried away by marine currents and waves, they depend entirely on winds, waves, and especially on underwater currents.
Dive with care
"Most species in their heyday can be seen at the surface of the water or at a shallow depth of centimetres or even 1-2 metres underwater. Usually people only see on the beaches in the zone where they stroll or step, only the jellyfish that come with the waves, while further inland, even 100 meters or even 200 meters from the beach, there are many more jellyfish," he tells APA-MPA.
In relation to the way of protection, he says: "There is no total way of protection. The main advice is to dive with a mask and if there are a lot of jellyfish of a stinging species such as Pelagia noctiluca, to get out of the sea for that day. But a combination of measures can go a long way to making sure we all enjoy swimming, such as putting on a thin lycra or neoprene suit to cover most of your body, a mask to see what's going on around you, controlling the winds so the wind goes inwards to keep the jellyfish out on the beach, making sure to record the jellyfish and uploading them to inaturalist.org (there is a mobile app for android and iphone) so that we can inform the world but also inform ourselves if there are jellyfish and always carry a jellyfish cream with us.
Symptoms of purple jellyfish sting
Nematocysts produce on human skin, erythema, swelling, burning as well as sometimes severe dermatonecrotic, cardiac and neurotoxic effects, which are especially dangerous in sensitive individuals.
Symptoms after contact - sting by jellyfish can be: Burn-like pain, often intense reddening of the skin, and in some cases the appearance on part of your skin of the jellyfish imprint, nausea, pressure drop, tachycardia, headache, headache, vomiting, diarrhea, spasm of the bronchial tubes, shortness of breath. In case of systemic symptoms (rare) such as: hypotension, hoarse voice, inhalation wheezing, generalized angioedema, extensive congestive rash, impaired level of consciousness communication, vomiting, immediate hospitalization of the patient is mandatory.
Useful advice
People are advised to check the weather and winds before going to a beach. It needs to have contrary winds to the direction of the beach (e.g. if the beach faces south, then to reduce the chance of jellyfish, the winds should come down from the north so that the swell it creates drives them away from the beaches). If there is plankton on a beach, it is recommended that people avoid swimming because the jellyfish feed on plankton and also their jellyfish cells are small, transparent and can be up to 10 metres long.
If there is a severe problem with purple jellyfish on a beach then it is recommended that people do not risk swimming and make sure they always have an anti-stimulant cream with them or a cortisone ointment that can be obtained from any pharmacy. Under no circumstances should citizens take jellyfish out to bury them in the sand, because the problem is transferred outside with the possibility of someone stepping even accidentally on a jellyfish, but also because in such large outbreaks, no matter how many jellyfish citizens see and take out, there are hundreds or even thousands more in the sea. This is not going to solve the problem.
Harmless jellyfish
Apart from the purple jellyfish there are other jellyfish that are not a danger to bathers and, according to Mr Tacles, should not be touched or taken ashore. And he explains why in conclusion: "The first reason is that if the jellyfish sting then we transfer the problem to land and if there are outbreaks such as for example of the purple jellyfish (Pelagia noctiluca) then we achieve nothing because a little further in the sea we have millions and billions of jellyfish that trying to get them ashore will break their transparent tentacles in shallow water or even on the beach which if we touch them afterwards or step on them again they can sting us.
Second reason is that some jellyfish like for example the Mediterranean jellyfish (Cotylorhiza tuberculata) when decomposing under the hot sun starts to smell bad within a few minutes.
Third reason is that jellyfish are very useful species because they consume phytoplankton and zooplankton in huge quantities. If there is enough phytoplankton (the brown colour on the surface of the sea) it creates various problems in the ecosystem but at the same time it spoils the holidays for tourists who don't like to swim in it. While zooplankton are tiny marine organisms, they include jellyfish no matter how few species are large and we can see them. An outbreak of zooplankton again creates a problem with intense itching on our bodies and we can't swim. In fact, it is sometimes even millions of tiny jellyfish invisible to the eye since their size is often a maximum of 1 or 2 mm and people have an itch just swimming."
Source: APE-MPA
Contents of this article including associated images are belongs Cyprus Times
Views & opinions expressed are those of the author and/or Cyprus Times
Source
