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The Jellyfish, the Suez Canal and the Ecosystem

2 July, 2017
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Coasts along the Mediterranean Sea are experiencing an invasion led by the Rhopilema nomadica, the largest and most venomous scyphozoan jellyfish present in the body of water shared by Europe, Africa and Asia. This jellyfish species has seen its population bloom in the Mediterranean in recent years, to the dismay of beachgoers and coastal inhabitants. 

However, what the human eye sees of jellyfish invading beaches is only a glimpse of what lies beneath the water.

This peculiar jellyfish invasion has made headlines from Egypt to Cyprus, because the Rhopilema nomadica seem to have strayed from their native habitats in the Red Sea and along the East African coast. The puzzling phenomenon has captivated many and an abundance of theories have cropped up to try and explain the enlarged jellyfish population. 


Where did the jellyfish come from?

Professor Bella Galil from the Steinhardt Museum of Natural History and Tel Aviv University explained to BECAUSE how this type of jellyfish entered the Mediterranean from the Red Sea.

Galil estimated that the Rhopilema nomadica entered the sea from the Suez Canal probably in the late 1970s, long before the recent expansion of the canal in 2015, contrary to popular belief.

The New Suez Canal, just like the old one, is expected to contribute to a phenomenon called "lessepsian migration", which results in species native to the Red Sea migrating to the Mediterranean, explained marine researcher Nada El Shanawany. The Rhopilema nomadica species has been spotted around the Mediterranean since 1989, she said.

“Lessepsian migration is still a consequence of man-made modifications of the natural habitat,” El Shanawany continued. “The claim that ‘construction of the new canal contributes to more lessepsian migration’ might be possible; however, extensive research must be done to confirm such a claim.”

On the other hand, pollutants and emissions from the New Suez Canal’s construction process could have contributed to the rise of the jellyfish. But, as El Shanawany emphasized, to understand the full impact additional and thorough research is needed.

Egyptian law requires that all construction projects carry out studies to asses their impact on the environment, but El Shanawany pointed out that the government often only releases sparse details in press releases, while keeping the full study behind closed doors.

"The Egyptian government needs to make the 'Environmental and Social Impact Assessment-ESIA study' available [as] press releases are not enough," she said, referring specifically to the file on the New Suez Canal. "This is in order to be able to back up arguments technically and avoid politicizing a scientific issue."

Galil further explained that the "original" canal was narrow and shallow, with a cross section of 304 square meters. In recent years, the canal was enlarged and deepened to accommodate larger vessels and in 2010 the cross section was increased to 5,200 square meters, which resulted in an increase of Red Sea water in the Mediterranean. 


So why so many jellyfish in 2017?

Egypt’s Ministry of Environment has cited a decline in the turtle population and other jellyfish predators, pollution and climate change as among the main reasons for the “unprecedented phenomenon” of the “increase in jellyfish numbers”.

However, Galil counters that “since the early 1990s, we have witnessed these large early summer swarms stretching hundreds of kilometers - there is no sudden boom in numbers. There are moderate, annual fluctuations in the size and duration of the swarms.”

“It's not about how big in numbers, it is about having a ‘bloom’, which is a large gathering in a small area," said El Shanawany in agreement with Galil. According to a study released by scientists at the University of British Colombia in 2012: "Massive blooms of Rhopilema nomadica have occurred annually along the southeast Levantine coast since the 1980s, directly interfering with numerous industries and resulting in significant economic losses."

“Our perception is biased by the proximity of the swarm to the shore,” Galil explained, adding that large swarms of jellyfish along the shoreline is largely determined by local conditions, wind and waves.

A bloom could be a natural one and could fade away, but given the current sightings and habitat deterioration, the bloom should be given attention and not taken lightly, El Shanawany asserted.


A severe change in the ecosystem

El Shanawany criticized the use of the general term “pollution”, notably when identifying a problem on a national level.

“It is about time [that we] finger point the exact sources of pollution to be able to take an action to diminish them,” she said.

Sources of marine pollution, such as fertilizer run-off, sewage dumping, overfishing and man-made activities such as unmonitored habitat degradation due to construction activities, need to be red flagged, El Shanawany explained.

Save the Water, an organization that conducts water research, highlights that the phosphate in fertilizer run-offs alone accounts for 40,000 tons a year in the Mediterranean Sea. Sewage in the basin amounts to an astonishing 720 million tons a year. This is not taking into consideration the construction waste and dust regeneration that carries materials that enhance the ecosystem in a way that allows for jellyfish to be more dominant and puts fish populations at risk.

To add to this, overfishing puts additional stress on fish populations. The European Commission recently released a statement admitting that 91% of the Mediterranean fish stocks are overfished. Consequently, fewer predators are around to eat the jellyfish and keep their numbers in check.

Global warming is an undeniable force that undoubtedly contributes to jellyfish outbreaks across the world, with Egypt and its Mediterranean neighbors being no exception, the biologists warned. According to a scientific paper published by Nature in 2016, the Mediterranean is itself a "hotspot of global warming". Its surface has continuously warmed since the mid–1970s, especially during the summer.

The study states that “the beginning of the 21st century (2000–2012) featured the highest SSTs in the Mediterranean Sea during the instrumental record”. Moreover, the increase from “the 1970–1999 to the 2000–2012 period in Mediterranean Sea surface temperatures (annual mean: 0.62 °C, summer mean: 0.86 °C) is considerably stronger compared to that of the global oceans (annual mean: 0.15 °C, summer mean: 0.19 °C)." This is a perfect medium for jellyfish to thrive, while fish and other organisms won't be able to cope as fast as jellyfish do with this trend of increasing sea surface temperatures, El Shanawany explained.

On this point, Galil begs to differ, and places blame on the Suez Canal.  

“Pollution and climate change indeed impact ecosystems. But do they explain away the swarming of Rhopilema [in the southeast Levant]?”  Other areas have higher levels of pollutants, yet are free of these annual swarms. The critical element is the man-made corridor to tropical marine biota, explained Galil, adding that Rhopilema is only one of several species of jellyfish and hundreds of other marine species that entered the Mediterranean through the Suez Canal and established populations in the sea.


Beyond the sting

Aside from human health, the jellyfish impact fisheries, coastal installations and the local ecosystem. Jellyfish prey on fish larvae, small fish, plankton and crustaceans. Thus, large swarms of jellyfish will, without a doubt, damage next year's fish population.

“It's not a matter of not being able to swim in the water,” stressed El Shanawany. “Even if the jellyfish disappear and people are able to swim again, sources of pollution and habitat destruction are still unacceptable and will remain a threat to our marine resources.”

As the jellyfish population spreads westward to Tunisia, El Shanawany insisted that people need to become more aware of how our environment is changing.

The marine researcher called for action: “If we assume that Egypt doesn't contribute to these sources, all activities are monitored properly and that these sources originate from other countries, it would still be a shame not to protect our resources from the ‘bad guys’.”

Photo courtesy of Shevi Rothman

Tags Mediterranean Sea Red Sea jellyfish Rhopilema Nomadica Egypt Environment ecosystem Climate change