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Purple jellyfish: In which areas there is an outbreak – How can we protect ourselves

Purple jellyfish are making their appearance again in the Greek seas.

Holidays “company” with jellyfish in the Greek seas and this year experts predict. The population outbreak of purple jellyfish – or Pelagia noctiluca as its scientific name – in the Aegean has started since October 2020 and if the same pattern prevails we will have to deal with them for another 1.5 to 2 years. Purple jellyfish are considered to be one of the most dangerous species of jellyfish in the Mediterranean.

The role of neurotoxin

Their sting is painful because of the neurotoxin they have, so bathers should be very well informed about what to do in case of a sting.

The outbreak of purple jellyfish in an area was observed before climate change about every 10 to 12 years and lasted a maximum of 4 years (on average 2-3 years). In 2015 until 2018 there was a strong population outbreak of this species in the Gulf of Corinth, in Malta the population explosion of purple jellyfish (Pelagia noctiluca) prevailed from 2018 to 2020, while we saw a reappearance in Malta and January 2022.

What the winter swimmers noticed

This year, they have been observed in various areas of the Aegean and the Ionian, while winter swimmers reported seeing this species of jellyfish in winter. However, their presence increases greatly in summer as its breeding conditions are favored due to the higher sea temperature. Their reproduction is also favored by climate change which raises the water temperature. At the same time, the reduction of the population of fish, which are their hunters, but also the reduction of the population of sea turtles, which is their main hunter, favors the spread of jellyfish.

How is the purple 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 the tentacles can reach up to 10 meters. It feeds mainly on sausages, various shellfish, placental crustaceans and fish eggs. The largest natural predators of jellyfish are the tortoise, the loggerhead tern, the tuna, the swordfish and the moonfish. When it is young its color is orange-brown and when it grows up it takes on an intense purple-purple color.

The recognition is made by its external morphological characteristics, ie what color it is, if it has dots or stripes on its bell, if its gonads are visible and what shape they have (for transparent jellyfish, such as Aurelia sp.), How are their tentacles in shape and if they have any different colors or stripes on their tentacles or bell.

“Natural outburst”

“Every species of jellyfish makes a natural outbreak every few years. e.g. The Mediterranean jellyfish (Cotylorhiza tuberculata) erupts every year in August, while the jellyfish Compass (Chrysaora hysoscella) erupts 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 e.g. climate change, overfishing, lack of predators, etc. has helped these outbreaks to occur more often and with greater spread “, explains to APE-MPE, Christos Taklis who is a Marine and Conservation Biologist and Administrator of the Hellenic Biodiversity Observatory.

Almost all species of jellyfish are found in deep water and away from beaches. But because their movement is passive as they are carried away by sea currents and waves, they depend solely on winds, waves, and especially underwater currents.

Inside, even more

“Most species in their outbreaks, we can see them on the surface of the water or at a shallow depth of centimeters or even 1-2 meters under the water. “Usually people see on the beaches in the zone that crumples or even steps, only the jellyfish that come with the waves, while further even 100 meters or even 200 meters from the beach there are many more jellyfish”, he states in APE-MPE.

Regarding the way of protection, he states: “There is no total way of protection. The main tips are to dive with a mask and if there are many jellyfish of some kind that stings like Pelagia noctiluca, to come out of the sea for that day.

But a combination of measures can help a lot for all of us to enjoy swimming, such as putting on a thin lycra or neoprene suit to cover most of our body, a mask to see what is happening around us, controlling the winds so that the wind goes in order not to bring the jellyfish out to the beach, we make sure to record the jellyfish and upload them to inaturalist.org (there is also an application for android and iphone phones) to inform the world but also to be informed if there are any jellyfish and always with us a cream for jellyfish.

Symptoms of purple jellyfish sting

Nematocysts produce on the human skin erythema, edema, burning as well as sometimes severe dermonecrotic, cardio- and neurotoxic effects, which are particularly dangerous in sensitive individuals.

Symptoms after contact – jellyfish bite can be:

Pain like burning, often intense redness of the skin, and in some cases the appearance of jellyfish imprint on part of your skin, nausea, drop in pressure, tachycardia, headache, vomiting, diarrhea, bronchospasm, shortness of breath.

In case of systemic symptoms (rare) such as: hypotension, hoarseness, inspiratory wheezing, generalized angioedema – extensive urticarial rash, communication-consciousness disorders, vomiting, immediate transport of the patient to the hospital is mandatory.

Helpful tips

Citizens are asked to look at the weather and the winds before going to a beach. It needs to have opposite winds in the direction of the beach (eg if the beach has a view to the south, then to reduce the possibility of jellyfish the winds must come down from the north, so that the ripples it creates drive them away away from the beaches).

If there is a plankton on a beach, it is recommended that citizens avoid swimming, because jellyfish feed on plankton and their urticaria are small, transparent and can reach 10 meters in length.

If there is a serious problem with purple jellyfish on a beach then it is recommended that citizens do not risk swimming and make sure to always have some antihistamine cream with them or some cortisone ointment that can be obtained from any pharmacy.

For no reason should citizens take the jellyfish out to bury them in the sand, due to the fact that the problem is carried out with the possibility of someone accidentally stepping on a nematode, but also because in such large outbreaks as many as the citizens see and to make out there are hundreds or even thousands more in the sea. This is not going to solve the problem.

There are also harmless jellyfish

Apart from the purple jellyfish, there are others that do not pose a danger to bathers and according to Mr. Taklis, we should not tease them or take them ashore. And it explains why concluding:

“The first and main reason is that if the jellyfish bite then we transfer the problem to the mainland and if there are outbreaks such as e.g. of the purple jellyfish (Pelagia noctiluca) then we do not achieve anything because a little further in the sea we have millions and billions of jellyfish that trying to take them ashore will break their transparent tentacles in shallow water or on the beach that if we touch them or step on in them again they can sting us.

Second reason is that some jellyfish like e.g. The Mediterranean jellyfish (Cotylorhiza tuberculata) when decomposed under the hot sun begins to smell bad within 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 color 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 do not like to swim in it. While zooplankton are tiny marine organisms, they also include jellyfish regardless of whether a few species are large and we see them.

An outbreak of zooplankton again causes us a problem with intense itching in our body and we can not swim. In fact, these are often millions of tiny jellyfish invisible to the eye since their size is often a maximum of 1 or 2 millimeters and people have an itch just swimming.

Source: ΑΠΕ-ΜΠΕ

Source: tanea

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