Israel's massive jellyfish swarm explained by University of Haifa experts

The density of the jellyfish population in the Israeli region have already disrupted a power station in southern Israel and there are concerns existing over the swarms affect on local marine life.

By
July 12, 2019 19:44
Jellyfish

Jellyfish [File]. (photo credit: INIMAGE)

 
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If you've been to an Israeli beach lately, you've probably noticed the swarms of jellyfish washed upon shore, possibly slithering through your legs as you take a dip in the water, with the possibility of a painful outcome in the form of a jellyfish sting awaiting you underneath the sea. But why is this happening?

The University of Haifa's Charney School of Marine Sciences are diving head-in to the Mediterranean nightmarish phenomenon of the Israeli jellyfish surge in order to gain a deeper understanding of the population's migration pattern and how to keep it under control to protect sea-life, beach-goers, surfers, tourists and sea-based infrastructure from becoming victim to the jellyfish pack.

"These swarms have been happening in our region since the 1980s and in varying abundances, so until we carry out large-scale quantitative assessments (rather than impressions) the jury is out on whether there is an increase," Dr. Tamar Lotan and Prof. Dror Angel, experts at University of Haifa's Leon H. Charney School of Marine Sciences explained in a statement.

However, the experts explained that this year the Israeli beaches are experiencing a superfluous anomaly this year because of the unusually high rainfall washing large amounts of nutrients into Israel's usually nutrient-deficient sea, providing tons of food to all marine life, including jellyfish. Lotan and Angel explained further that "the swarm continues in this region year after year because the jellyfish" have already become well established within this area over time.

The deep density of the jellyfish population in the Israeli region have already disrupted a power station in southern Israel and there are concerns existing over the swarms affect on local marine life.

"The jellyfish compete directly and quite efficiently with larval and young finfish over planktonic food, and in some cases the jellies have caused these fish populations to 'starve.' [They] are predators and massive swarms/blooms with large predation pressure can cause ecosystems to become unbalanced," Lotan and Angel said regarding the numerous impacts the jellyfish have on the ecosystem.

"Jellyfish blooms means massive biomass in the water column and when that material sinks and decomposes on the seafloor, it can either cause formation of hypoxic and anoxic sediments (dead zones) or a feast to bottom dwellers that enjoy the food. [The] blooms can cause mechanical clogging of coastal power plants that use seawater to cool their turbines, problems to desalination plants that use seawater to generate freshwater, problems to fisher-folk that want to target finfish or other marine species, all marine recreation, and aquaculture farms that grow fish in cages."

Unfortunately, these swarms are unavoidable.

The University of Haifa experts claim that these migrations are a natural phenomena, and that work is focused on understanding the "dynamics of the swarms better" to be able to predict their arrival and use preventative measures to reduce the affect these faceless-spineless creatures have on the surrounding environment.

The experts allude to the fact that over-fishing the finfish population, a natural competitor to the jellyfish, in the Mediterranean Sea could give the swarm the upper-hand when competing for food and that maintaining healthier populations of these fish could reduce the size of the jellyfish pack in years to come.

"The same argument is applied to coastal development. Many finfish have natural nurseries near the shore and if coastal development encroaches on these, this adds pressure to natural fish populations and threatens their survival. A solution to this is to establish marine protected areas where coastal development does not happen, to protect natural biota - this may also ultimately reduce jellyfish swarms," the two experts explained.

"Jellyfish also seem to be less affected by pollution than other marine groups. So if the sea is polluted by chemicals or other agents, the jellyfish may fare better than other groups, once again boosting their populations and success in comparison to their competition. The solution here is of course to reduce marine pollution."

However, the swarm is not all bad. Marine biologists from the University of Haifa are conducting an experiment on jellyfish to find out if the mucus they produce would be a good material to capture micro plastics in treated water systems before the water is released back into the sea.

Angel, who is leading the research along with PhD candidate Hila Dror, told The Media Line that the mucus could be manufactured into two potential products – a sticky mesh that would filter out plastic particles, or a chemical powder that to be added to treated wastewater.

The researchers are currently testing the properties of the mucus to see how long the substance remains active. Angel says that the mucus can become watery and less effective in capturing particles over time as the enzymes that break down materials lose their ability to function.

It is still unclear to the researchers how long it takes for this breakdown to occur. Currently, they are testing the mucus at different temperatures to see if cooling or freezing can prolong its plastic-capture activity.

Dror and Angel routinely survey the Mediterranean waters off the city of Netanya for jellyfish. They look mostly for the Rhopilema nomadica, or nomad jellyfish, which is the species most frequently seen washed up on Mediterranean shores and look like large, white plastic bags.

If stung by a jellyfish, use seawater, not fresh water, to clean the affected area. Likewise, despite what the TV sitcom Friends may have led you to believe, human urine also does not effectively clean the area.

While getting stung by these creatures is not fun, jellyfish "have a role" in the marine ecology, explained Dr. Dor Adelist, a marine ecologist also from the University of Haifa's Charney School of Maritime Studies. "They clean the sea, they serve as food for a great variety of marine creatures like sea turtles and fish - and the human being can also use them as healthy food - cosmetics, pharmaceuticals and in Israel people are already working on the innovative development of using their liquid to clean micro-plastic waste, for example, in wastewater treatment plants."

"It is reasonable to assume that by the end of July they will be here, and in August they will disappear from here and we will be able to return to the sea without fear," he said.

Shanna Fuld  and Jerusalem Post Staff contributed to this report.


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