17 September 2014

Interview: Jellyfish Bloom expected in August

 - Monday, 16 April 2012, 00:00

by Keith Micallef

Though it is only April, reports of jellyfish sightings around the Maltese Islands have already made the news. Keith Micallef recently met with marine biologist and founder of the Spot The Jellyfish Campaign Alan Deidun about the subject. According to him, though jellyfish blooms are still highly unpredictable, evidence suggests that next summer swimmers are likely to encounter jellyfish towards August and not by late May as is the norm.

According to marine biologist Alan Deidun, any jellyfish blooms likely to appear next summer will come around later than usual. He is also expecting new species of tropical jellyfish to reach our shores.

At the beginning of the interview Dr Deidun distanced himself immediately from any foolproof predictions and stated that in this field one can only dare an educated guess. He claims that evidence this year so far suggests that adult jellyfish came to the surface to reproduce in warmer waters much later than usual. While normally this process takes place in December and January, this year this happened towards the end of February. Incidentally this is the reason for such huge numbers of dead jellyfish which are usually reported in winter.

As a result mauve stingers (the common pink jellyfish) this year may appear later than usual, maybe in August, whereas normally they start to appear in May or June. However this is just a guess, as this is a highly unpredictable subject. The fact that last year was a jellyfish-free summer is a clear example.

Dr Deidun also predicted that new tropical species may be recorded this summer. “This is due to the fact that in neighbouring countries new species have been reported. The Australian Spotted Jellyfish in Italy and the Compass Jellyfish in Spain are two examples. As a pre-emptive strategy, we place such species on our educational leaflets.”

Asked about any particular chronological patterns in jellyfish blooms, Dr Deidun explained that from records dating back 150 years, it is being observed that in recent years peaks have been more frequent and pronounced. However large masses of mauve stingers have been observed for decades and in the eighties local water polo games had to be cancelled and teams had to go and train abroad. He recalled that back in the late fifties an advert of a jellyfish repellent cream was published in a local newspaper.

Economical, social and ecological disruption

In the ecological chain, the role of jellyfish is to act as scavengers and so serve as a natural means to eliminate the weakest organisms. Another function is to filtrate water from plankton. The main problems arise when jellyfish appear in huge numbers all of a sudden. The Canary Islands right now are experiencing a bloom of apocalyptic proportions and mauve stingers are literally being bulldozed from the beaches. In the last 28 days 3.25 tonnes of jellyfish were removed from a single beach.

Dr Deidun cited the positive impact that jellyfish may be having on the diving industry. He floated the idea that authorities need to seriously consider promoting a new niche of jellyfish tourism, also in view of the fact that overfishing is threatening the already fish depleted seas around Malta.

Regarding the ecological benefits or threats that jellyfish pose in general he said that huge outbreaks of jellyfish are having a negative impact on the overall population of fish as they are consuming large amounts of plankton and other foods on which the fish depend. The traditional kinds of jellyfish use their stingy tentacles full of capsules to squirt their venom to catch their prey. Other kinds of jellyfish called comb jellies which are not stingy have sticky tentacles, which have the same purpose. The latter are becoming more popular with divers as these may be handled freely without any risks. Another form of jellyfish that fishermen are familiar with are called salps, which resemble long chains of jellyfish which may stretch several kilometres.

“As a marine biologist I am focusing more on the threats especially those caused by stinging jellyfish and the blooming population which causes an ecological imbalance. In some cases jellyfish are producing so much mucus, which is a gelatinous substance, that parts of the sea are becoming toxic and consequently impacting negatively on marine life. The best term that can describe the overall impact on marine life that jellyfish are causing is disruption,” said Dr Deidun.

The effects of alien species entering the Mediterranean

Malta’s position in the centre of the Mediterranean is a crucial factor when it comes to new species reaching our shores. The main reason is that new species entering the Mediterranean from the Straits of Gibraltar or from the Red Sea, will find it very hard to make it to the centre due to various factors, mainly the distance and the sea temperature.

Last year the local scientific community was shocked when evidence of the presence of nomadic jellyfish in Maltese waters was published by Dr Deidun. This kind of jellyfish can reach huge proportions of about half a metre in diameter and made its way from the Red Sea in the late eighties and early nineties. In Eastern Mediterranean countries like Israel this has become a national issue causing power cuts due to large numbers of nomadic jellyfish blocking the cooling systems of the power station. In other countries like Lebanon and Turkey, it is resulting in financial losses for fishermen who have to discard their nets once they become blocked with this species of jellyfish. On one particular occasion in Israel a line stretching about 50 kilometres and two kilometres wide was reported, which is equivalent to 100 square kilometres of nomadic jellyfish.

This huge mass devoured large amounts of plankton to sustain itself thus stressing even more the already scarce food supply for marine life in the region. Other impacts were the closure of long stretches of beaches as this kind of jellyfish is a painful stinger like the Portuguese Man of War, which as the name suggests is also an alien species to the Mediterranean as it comed from the Atlantic.

New species reported in Malta so far

Prior to last year it was believed that the furthest place that nomadic jellyfish were recorded was Greece. “However last year I came across some footage dating back to 2004, which clearly shows this alien species in Maltese waters. Fortunately since then no further reports have surfaced and this could indicate that no mating has taken place here. This phenomenon is called Leseppsianism after the French engineer, Ferdinand de Lesepps who designed the Suez Canal in the nineteenth century. More recently this year we are witnessing crystal jellyfish which is innocuous to humans. Since the launch of the Spot the Jellyfish campaign in 2010 about eight species have been recorded in Malta for the first time, some of which were present before but were never scientifically reported.

“One particular case was that of a French student, who was only 12 years old and discovered a new species, called the blue button in Dwejra, while she was on holiday. Previously it was believed that this species thrived in tropical waters.”

Another recent discovery was the ‘upside down jellyfish’ which as the name suggests lives on the seabed in an inverted position with its tentacles stretching up. Just like plants this species needs sunlight to grow and its tentacles serve that purpose as they stretch towards light. The phenomenon of Leseppsianism is also common in fish and crustaceans.

It is estimated that two thirds of alien species come from the Red Sea and the rest from the Atlantic Ocean. The African Moonfish is a species recorded in Malta which is very common in the tropical water of Equatorial Guinea. The factor that may be tilting the balance towards the east is the tropicalisation of the Mediterranean. Therefore alien species from the Red Sea may be more adaptable to warm waters than those from the Atlantic. In Malta we get some species from both extremes though species from the East very rarely reach our shores. Several exceptions are the cornet fish and the rabbit fish which are even ending up in the local fish markets, such as that in Marsaxlokk.

Causes of jellyfish blooms

Replying to popular belief that pollution may be one of the causes for the increase in the number of blooms, Dr Deidun said that this is a million dollar question. Among the most important factors overfishing is one of the causes, with fish being replaced by jellyfish. Secondly the increase in sea temperature is greatly influencing the life cycle of the jellyfish which is being accelerated and also causing certain species such as the mauve stinger to survive in winter.

“In fact this year we are witnessing abnormally large mauve stingers of up to 15 cm diameter which may be due to the fact that they manage to survive winter. As regards pollution – specifically the use of fertiliser in agriculture, which is washed down to sea – this also stimulates the growth of some species. The fourth reason is thought to be the increase of artificial surfaces, as jellyfish prefer to lay their eggs on flat surfaces like jetties, pontoons, terminals and wharves.

“Contrary to popular belief, the decrease in population of sea turtles which feed on jellyfish, is also having an impact, however this is thought to be a marginal one and not a major one as some are claiming.”

One of the most feared kinds is the box jellyfish which in some parts of the world like Australia is lethal. Dr Deidun points to the existence of tens of thousands of this kind of species and says that none of those in the Mediterranean are deadly. The notorious Australian species is listed as the fourth most poisonous organism in the world, and claims several lives each year. The carybdea marsupialis, which is present in Malta, gives a nasty sting but is not lethal and therefore, sweeping statements mentioning box jellyfish have to be treated with caution so as not to create unnecessary panic to swimmers.

Swimmers urged to be cautious and on the lookout

Dr Deidun urged caution to swimmers especially in jellyfish infested waters as these may inflict serious injuries and complications. From a medical point of view another factor that plays a major role is the hyper allergenic response of the individual as the immune system of the body reacts differently when in contact with a threat. In other words some people may be more ‘resilient’ to jellyfish. “In Malta we can consider ourselves lucky as we are not exposed to the amount of alien species that swimmers in Gibraltar or Egypt come across,” said Dr Deidun.

Spot the Jellyfish Campaign

Asked about the Spot the Jellyfish campaign, Dr Deidun described it as a citizens’ science initiative in which large scale scientific projects are carried out involving the public for data collection.

“In Malta we started relatively late when compared to other countries. Initially the campaign was mainly targeted at children, but due to the huge feedback we got we extended the campaign nationwide. We tried to be as innovative as possible in our approach and the public can submit a report simply by sms. Other means of submitting reports include the website, which is updated in real time or by post using one of our leaflets. Another initiative is the placing of informational boards round the island’s beaches to educate swimmers. This year we are replacing them with aluminium boards which are more weather resistant and may be used for several years, even though they have to be removed in October.

“Overall I think this campaign was a success, and we received about 800 reports in three years.” The peak season is usually in August with five or six daily reports. People can get involved by visiting

There is also a global campaign in Monterey Bay Aquarium in California whose website on invites users from all over the world to report jellyfish sightings.

The Medjellyrisk Project and other initiatives

The Medjellyrisk project is a joint venture project between the University of Malta and others from Italy and Tunisia, and is currently seeking EU funds. Part of this project involves the publication of a specialised guide about treating jellyfish stings, categorised according to the species being dealt with.

Other initiatives in the pipeline include local involvement in DNA research on several samples of jellyfish round the Mediterranean, which is being carried out by an Italian student of Salento University in Lecce as part of his doctorate studies. Right now Dr Deidun is also gathering scientific data on the effects of fish farms on the quality of sea water. This is being carried out using satellite photography.

Treating jellyfish stings

The most crucial factor is determining what species one is dealing with. While some treatments may prove to be beneficial, in some cases they can make the symptoms worse.

The venom of a jellyfish is composed of proteins and any substance which destroys the protein chain is deemed to be good. Acidic liquids such as vinegar, citric juice, pineapple juice and meat tenderiser in the majority of cases can be used.

Dr Deidun cited that the official advice from the public health is that each case has to be treated separately. Obviously the main flaw of this approach is that it is not always possible to determine the exact species of the jellyfish in question.

In this case, there is still some advice to follow such as:

• Avoiding contact with fresh water as this will cause the venom capsules to spread on the affected area at a greater rate

• Avoiding scrubbing the skin and if possible one should to remove parts of the tentacles using a pair of tweezers.

• Do not expose the affected area to extremes in temperatures such as treating it with hot water or ice

• Apply alcohol to the area

• Seek immediate medical aid if having difficulties in breathing or swallowing, chest pains or intense pain in the area

The emphasis must be on educating the public to recognise the jellyfish. With reference to various jellyfish creams which claim to treat stings, these are effective but only to alleviate some of the pain.


Dr. Alan Deidun is a Senior Lecturer at the Physical Oceanography Unit of the IOI-Malta Operational Centre of the University of Malta, being primarily trained and with experience as a coastal and marine biologist. He holds a PhD in biology and is recognised as a Chartered Biologist by the Institute of Biology of London.

Though his earlier academic studies were in coastal biology he later shifted to marine biology. The turning point was when he decided to follow a diving course while still a university student. Once he immersed himself in the relatively unknown marine world he was eager to discover more and so decided to specialise in marine biology.

He has published over 45 peer-reviewed papers in several high-profile academic journals on various aspects of coastal and marine biology and has coordinated the marine ecology section of numerous recent Environmental Baseline Study (EBS), Environmental Impact Assessment (EIA) and Appropriate Assessment (AA) studies. He has lectured biology at various levels for the past nine years and has contributed to numerous University taught and field courses.

Since 2001 he has also penned hundreds of popular science articles for various media portals, including newspapers, magazines and journals and is scientific advisor to a number of local environmental NGO’s. He is also a qualified PADI-certified SCUBA diver and a keen footballer.

In 2009 he ventured in the political arena, by contesting the European Parliament elections with the Nationalist Party.

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