Méduses

A. Observations

Professor Stefanao Piraino from the University of Salento (Department of Biological Sciences) in southern Italy, is a specialist in the Mediterranean. He is responsible for a scientific project aimed at identifying jellyfish and assessing the extent of their proliferation in the context of global warming. This is done to cover a set of basic information, for swimmers, scientists, industry and local communities. The latter confirms the convergent analyzes and observations on the proliferation of jellyfish already advanced by many of his colleagues on an international scale.

As an example, Stefanao Piraino explains that on the small Italian island of Lampedusa, which hosts more than 300,000 tourists each year, some beaches remain inaccessible for much of the summer, with all the financial consequences that this may imply on a seasonal economy entirely devoted to tourism.
Similarly, this frightening phenomenon can be seen in Spain, Tunisia, Morocco, France, Israel, the United Arab Emirates, Thailand and in many other countries.

Professor Piraino's work is supplemented by several private and public initiatives, whether they are more or less ambitious projects of observation, analysis or census.

- The creation of the "Jellyfish observation portal in the Mediterranean" by the French company ACRI-ST (www.acri-st.fr) is a citizen action collaborator mobilizing every one of us.

With the help of our observations we can all contribute to real-time observation and identification of places where jellyfish can be seen; potentially along the Mediterranean coastline's thousands of kilometers. This information will then be collected on a dedicated website (meduse.acri.fr) presenting a map indicating the presence or absence of jellyfish for one day, two days and more.
It is certain that this type of initiative will become widespread throughout the Mediterranean basin which is already currently very active on the Provence Alpes-Côte d'Azur region.
It appears that the jellyfish population has grown steadily for four years and that this is part of a broader phenomenon on a global scale.

By association, the multidisciplinary project called Jellywatch carried by the Oceanological Observatory of Villefranche sur mer (www.obs-vlfr.fr) aims to understand and in particular predict through satellite tools, meteorological, hydrodynamic and biological, massive appearances and the invasive Pelagia Noctiluca species of jellyfish on the shores of the Provence-Alpes-Côte d'Azur region.
The Jellywatch project's strategy is to bring together researchers from different research organizations (LOV, MIO-Toulon and MIO-Marseille) and private companies (ACRI-ST and DYNASUB) in order to combine different types of expertise.

Three complementary approaches are in synergistic:

- the observation of current and past abundances, offshore and on the coast. The site http://meduse.acri.fr allows everyone to participate in monitoring the presence of Pelagia Noctiluca.
- experimentation to understand the organism's nutrition and the development,
- modeling to simulate their transport by ocean currents and predict their stranding on the coasts.

This project financed by the PACA region and the ERDF Program has been labeled by the PACA sea pole (www.polemermediterranee.com).

- Israel sets up a "jellyfish alert" (2012)

As each year thousands of jellyfish approach the Israeli side, the authorities have opted for the establishment of a new prevention and cooperative alert system. This system must make it possible to limit the damage of hundreds of bites inflicted to swimmers throughout the summer season.
The first pilot beach to benefit from this warning system is that of Beit Yanai located a few kilometers from the city of Netanya.
Located on the beach, an electronic panel informs bathers in real time about the presence of jellyfish in the water.

This panel is divided into three danger alert levels:

- Level 1: no danger
- Level 2: some jellyfish, caution
- Level 3: a lot of jellyfish: avoid swimming.

Every summer for several weeks, jellyfish invade the waters of the Israeli coast, becoming a great nuisance for many bathers and rescuers. It is also important to note that even vacationers on the beach may be affected by these pelagic invaders. Indeed, the jellyfish stranded on the sand continue to pose for a few hours a real irritating danger for all walkers and children who are left unattended.

The Israeli warning system is set up in real time, based on information provided by lifeguards and swimmers. This is a pilot project that could be scaled up and widespread across the country's beaches.

This system's most important advantage:

In the end, bathers wishing to plan a visit to a beach can check the state of the jellyfish threat via a dedicated website and in advance.

- The ECOJEL project initiated by Ireland and Wales (UK) to estimate the increase in the number of jellyfish in the Irish Sea (2007)

The ECOJEL project (www.jellyfisch.ie) aims to identify, quantify and manage the threats and opportunities that may accompany the foreseeable increase in the number of jellyfish outbreaks in the Irish Sea as a result of climate change.
The project, a collaboration between Swansea University and University College Cork, will examine the potentially positive and negative impact of increased jellyfish numbers on the ecosystem, as well as their socio-economic impacts on the ecosystem, tourism, aquaculture and fisheries sectors.

Works on five axes:

- action and public awareness campaign
- determination of the movements and origin of harmful jellyfish through the development of innovative tracking technologies
- work to identify the impact of jellyfish on fisheries and aquaculture
- an analysis of the economic potential of sustainable jellyfish farming in the ecotourism sector
- creation of a "center of excellence" for jellyfish research between University College Cork and the University of Swansea.

EcoJel is an excellent example of a project that creates cross-border links, raising awareness of climate issues and adopting measures to respond to the challenge of climate change.

B. Issues and Implications.

Similarly, Josep María Gili, a jellyfish researcher at the Institute of Ocean Sciences in Barcelona, believes that jellyfish are "an increasingly serious problem for the Mediterranean, as it is for the oceans in the rest of the world".

The spread of toxic jellyfish in the Mediterranean:

The species that multiply in the earth's seas are very different and all represent specific issues.
In the Mediterranean it is one of the most stinging species. The Pelagia Noctiluca jellyfish. Observed in very high concentrations near the coast with swarms up to several kilometers long, several meters deep and having a density of more than 30 to 40 jellyfish per m2, their frequency of occurrence has become yearly. Existing analyzes that were based on complex cycles until the beginning of the year 2000, are in fact currently being questioned. Although according to observers the most affected geographical areas are Sicily, Sardinia, Malta, Lebanon and Israel, in fact this phenomenon leaves no maritime area untouched. So much so that every summer this subject becomes more and more worrying and requires more and more radical measures on the part of local elected officials and certain private actors (hotels) wanting to preserve tourism which has already been weakened by a difficult economic context.

Pelagia Noctiluca:

The Pelagia Noctiluca jellyfish, also known as the pelagic jellyfish, is a cnidarian from the family Pelagidae.
In Greek, Pelagia means "sea", nocti means "night" and luca "light". Pelagia Noctiluca can then be interpreted as a marine organism with the ability to shine in the dark. This is possible thanks to a luminous mucus produced by the animal's endoderm when it is disturbed by the waves.
This species of jellyfish, known in Europe as the mauve stinger amongst many other common names, is widely distributed in all warm and temperate waters of the world's oceans, including the Mediterranean Sea, Red Sea and Atlantic Ocean. However, some observers highlight a process of colonization towards the North Seas, which can be explained through the occurrence of global warming. This is a phenomenon which has already observed for several decades in various species of fish, and also plankton.
This cnidarian has eight tentacles, including stinging nematocysts which can cause severe pain in the case where it comes into contact with the skin. It is covered with tiny red dots, which are actually stinging cell bundles. It has a reddish color, ranging from orange to purple and with pink passing through its body. Its ectoderm (hat) is transparent and non-irritating and leaves its mesoglea, its endoderm and its gonads exposed. It also has, at the bottom of the umbrella, four jagged mouth lobes, pinkish, stinging and covered with sticky mucus, which capture and paralyze prey (small animals that are part of the zooplankton and which will be brought to its mouth. Its reproduction differs from most other jellyfish, since it spreads eggs and sperm which, after being fertilized, will become small larvae that will pass directly into the jellyfish stage and gradually become adults.

C. The main causes of the spread of the jellyfish:

- Global warming

The water temperature tends to play a direct role in jellyfish outbreaks by promoting their development.
Thus, it is clear that in tropical waters, jellyfish outbreaks occur throughout the year and are regulated only by the predation of jellyfish-eating species such as dolphins and killer whales.
In the same way, in the harbor environment and at the foot of the hot water discharges from nuclear power stations, species like Aurelia aurita bud all year round.
The Baltic Sea is no exception to this development. The cooling circuits of the many nuclear power plants on its shoreline constantly discharge millions of liters of water at a constant temperature of around 16 degrees Celsius. These artificial conditions, compensating for the low temperatures that previously characterized the winter period in the Baltic Sea, eventually ended up by disrupting the jellyfish breeding cycles. The latter, constantly breeding, eventually took control of this sea, with a direct impact on fish stocks. Jellyfish have devoured herring eggs and larvae and, in a few years, the Baltic Sea has lost almost all of its fish population. Jellyfish have now moved-in permanently. This is a good example of global warming's effect, reflecting the dysfunction caused by rising temperatures.
The Mediterranean Sea does not escape this phenomenon either.
Until the 1990s, the presence of Pelagia Noctiluca had a frequency of twelve years, associated with early, hot and dry springs. In recent years this rhythm has been significantly disrupted. By causing an increase in the temperature of this closed sea, global warming could as on the Baltic mark a permanent presence of Pelagia on our coasts. This development would be a disaster for all the tourism economies concerned.

- Disappearance of natural predators

Many marine animals, such as turtles and tuna disappearing, it directly favors jellyfish outbreaks. According to specialists, tunas, especially blue-fin tuna that are currently victims of the global process of over-exploitation of natural resources their disappearance is one of the direct causes of jellyfish outbreaks. The disappearance of sea turtles, major users of jellyfish, would also be one of the main causes.
With this in mind, scientists and biologists in Spain are trying to reintroduce sea turtles. It is through ecological action that they are trying to control Pelagia Noctiluca's presence. A late response based on a long-term ambition that seems already outpaced by the magnitude of an exponential outbreak phenomenon.

- Disappearance of fish as a result of overfishing

The ecological niche left empty due to the overfishing of pelagic fish is occupied by jellyfish, the latter feeding on the same food (plankton) and occupying the same environment (full water).
A new IRD study in partnership with Namibia (publication/bulletin of marine science) confirms that the seas preserved from the over-fishing phenomenon, unlike the Sea of Japan and the Mediterranean Sea, are significantly much less exposed to the proliferation of jellyfish.
If global warming persists in the years to come, it is probably inevitable that jellyfish populations will increase dramatically in all the world's seas and oceans by condemning fish which are increasingly threatened by over-exploitation and as a result of competing with them.

- Pollutant discharges of anthropic origin

The release of estradiol into the ocean is one of the indirect causes of jellyfish proliferation. Hormones contained in drugs for the treatment of menopause and contraceptive pills are released into the ocean and cause mutations in fish. These very powerful hormones and their unfiltered molecules as a result of passing through unsuitable purification plants would influence the sexual development of the fish by changing them by hormonal modification into females. The depletion of the males would thus prevent the reproduction of these fish more and more and be instead in favor of the proliferation of jellyfish which by their ability of budding and asexuality would be naturally protected against the effects of these hormones.

D. Main consequences:

The consequences of these outbreaks are multiple and most often harmful to humans and the environment. Apart from their impact on fishing, fish farming and coastal industries, jellyfish pose a direct threat to coastal economies which are developed and organized on seaside tourism.
Thus, stinging species of cnidarians, such as Pelagia Noctiluca which are present all around the Mediterranean basin, are real threats to swimmers.
In response to this unwanted presence, the municipalities concerned are forced to take more or less appreciated and tolerated measures by holidaymakers, such as closing beaches, capturing jellyfish en masse or installing anti-jellyfish nets.

Some figures:

In terms of public health, the bites and envenomations caused by these undesirable aquatic visitors cause lesions which can be more or less severe and may sometimes require hospitalization.

- 150,000 bites per year are recorded on average in tourist resorts in the Mediterranean.
- In Valencia, Spain during the summer 2009, more than 11,000 tourists were stung on only 100 km of coastline with a cost estimated at nearly 2.4 million euros.
- In 2007, the Spanish authorities counted more than 70,000 jellyfish stings on their entire coasts.
- In Italy, every care taken in hospitals following a jellyfish burn costs an average of 220 euros.
- French firefighters reported 5,000 interventions on jellyfish stings in 2011 for the Alpes-Maritimes alone.
- The access to Boucan Canot and Roches Noires beaches was strictly forbidden on Wednesday, June 5th, 2013. The Saint Paul City Council made this decision after the lifeguards found a significant presence of jellyfish in these beaches' waters.
- 7,795 jellyfish stings recorded on the beaches of the Alpes-Maritimes during the 2014 summer season.
- Over 100 jellyfish bites during the day of July 20, 2015 on the only beach in La Salis, municipality of Antibes in the Alpes-Maritimes.

E. Solutions

If many researchers and scientists are now fully involved, to understand and analyze the origin of the proliferation of jellyfish in the world's seas and oceans and try to identify a set of solutions, it is completely unlikely that effective responses, if they can be found, be envisaged at least for several decades. Faced with this objective observation and in order to be able to propose adapted, effective and immediate solutions to local decision-makers and tourism professionals to prevent the occurrence of these invasive situations, our engineers, in close collaboration with former professional divers of Comex, since 2009, have conceptualized and developed high-performance anti-jellyfish floating barriers.
These floating dams, available in different flotation variants, have been specifically adapted for the protection of bathing areas.
In constant evolution, they benefit from the knowledge and technical advances acquired by our company in the fields of aquatic and underwater containment and in the field of operational experience.
Exceptional overall stability, continuous waterline and optimized wave resistance make our dams excellent aquatic equipment.

In the same way that floating containment dams are the first line of defense to control the occurrence and spread of marine pollution, it is now accepted that our BSM or BAM14 adapted dams are the only reliable and effective way to date to preserve completely safe swimming areas.