"Our coal-fired power stations are located by the sea because it takes a lot of water to cool them down," Israel Electric Corp spokeswoman Iris Ben-Shahal told Haaretz. "At that entry point of the water into the cooling systems, we have filters to keep foreign bodies out. The jellyfish, and other things like sea plants, stick to the filters and clog them."
While IEC stayed open despite the swarm -- workers managed to get them unclogged in time -- other power plants haven't been so fortunate. In 2013, a giant swarm of moon jellyfish shuttered the world's largest boiling-water reactor, located in Sweden. The same thing happened at the plant in 2005.
Stuff like this happens more often than you'd think; about two or three times a year, jellyfish blooms cause serious problems for power, desalination and other plants, according to Lucas Brotz of the University of British Columbia's Institute for the Oceans and Fisheries. "In some cases, it's caused nuclear power plants to have near meltdowns," Brotz told The Post.
"I wouldn't say jellyfish are doing this intentionally," Brotz added.
Massive blooms of jellyfish inadvertently get stuck in the plants. They're built on the water's edge and suck in ocean water to cool their systems. Sometimes that water has a bunch of jellyfish in it. Some of the blooms "can almost look like they're more jelly than water," Brotz said.
While having a cooling system shut down can halt operations, a spokesman for the Swedish nuclear power plant that faced swarms in 2013 said at the time that there was no risk of nuclear accident. Representatives with the nuclear power industry contest the notion that jellyfish have caused severe safety problems, such as near meltdowns, and call such characterizations “exaggerated.”
“Given the multiple safety layers that exist at U.S. nuclear energy facilities, periodic complications caused by the presence of jellyfish have not threatened safety, period,” said Steve Kerekes, spokesman with Washington, D.C.-based Nuclear Energy Institute.
The rise in jellyfish has become a problem for industry. Brotz coauthored a 2012 paper published by Hydrobiologia: The International Journal of Aquatic Science that analyzed 45 of the world's large marine ecosystems with an abundances of jellyfish. The researchers estimated that 62 percent of them had increasing trends since the 1950s.
The study authors note there isn't a single cause of such blooms and many populations fluctuate along with the ocean's climate. "Jellyfish have bloomed for hundreds of millions of years and are a natural presence in healthy ecosystem," they write.
But Brotz explained how humans can be exacerbating the rise in blooms, such as with over-fishing that removes jellyfish competitors and predators.
Jellyfish also survive better than most marine life in dead zones, those oxygen-depleted spots in the ocean that can come about because of pollution. And coastal development gives some jellyfish species more shaded habitat when they're in the polyp stage, which they love.
Brotz said warming ocean waters can cause jellyfish to expand their ranges, have more babies sooner and stick around in certain spots longer.
Jellyfish that get introduced to foreign waters and turn into invasive species can also become massive blooms, Brotz said. This can happen when ships take on ocean water to even out their load or when the polyps, stuck to the sides of boats, get transported elsewhere.
Haaretz reported that the jellyfish that swarmed the plant last week appear to be Rhopilema nomadica, considered invasive in the Mediterranean Sea.
Jellyfish don't just swim aimlessly, but the ocean's currents can push a big blob into unsuspecting territory, Brotz said. So it's become crucial for industry to try to figure out ways to predict jellyfish. Researchers have asked the public to pitch in on the citizen-science research site, Jelly Watch, by reporting jellyfish sightings.
"We're not going to be able to stop jellyfish, but if we can warn a power plant or aquaculture [farm] or even a swimming beach for tourists, 'hey, there's going to be a lot of jellyfish today,' they can prepare for it," Brotz said.
[This post has been updated.]