Over the past few days, schools of jellyfish inundated the seawater cooling
system at the Orot Rabin coal power plant in Hadera, requiring a mechanical
“trash-rake” to pull them off the bars of the undersea-filtration
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Trucks were subsequently utilized to transfer the jellyfish to a
mass disposal area, the Israel Electric Corporation said.
While the plant
suffered from the jellyfish implosion from the weekend through Tuesday, by
Wednesday the problem was under control, and the facility did not have to shut
down during the cleaning process, according to Deputy Spokeswoman Iris
The Environmental Protection Ministry has granted the IEC a
permit to capture the jellyfish and then shuttle them in huge containers to a
dumping site, she explained.
The trash-rake, a mechanical-comb system, is
regularly used about twice a day to clear fish, plastic bags and jellyfish – but
during times of “attack,” the rake is in operation 24 hours per day, IEC marine
ecologist Dr. Anat Glazer said.
The problem was so great that the
IEC took extra precautionary measures during the onslaught and attempted to
seize some of the fish before they got to the site, according to Ben-
“Some people went to boats and put out nets to catch the
jellyfish before they came, because it was such a huge attack,” Ben- Shahal told
The Jerusalem Post
on Wednesday. “We thought the strainers and combs wouldn’t be
able to catch them all.”
But Glazer said that while these boats were
“better than nothing,” they collect very few compared to the amount pouring in
during periods like the past few days. In the past, she said she tried to
install a “Jacuzzi-like” screen of bubbles, but the pressure wasn’t strong
enough to block them.
The jellyfish are not particularly drawn to the
power plant cooling systems; rather, they “largely drift with the currents,
migrating only vertically in the water column as non-visual, ambush feeders,”
according to Dr. Bella Galil, senior scientist at the National Institute of
“The jellyfish are not ‘attracted’ to the water intakes –
they are ‘sucked in’ – involuntarily,” she told the Post
While by Wednesday the waves were no longer shuttling the
jellyfish in such mass quantities, the trash-rake was still operating, Glazer
said. Experts couldn’t confirm whether the hordes are larger than previous
“Our impression – and I emphasize the word ‘impression,’ which is
not a scientific word – is that it’s considerable this year,” said Prof. Ehud
Spanier, a marine biologist and ecologist at the Leon Recanati Institute for
Maritime Studies and in the Department of Maritime Civilizations at the Leon H.
Charney School for Marine Sciences.
“One thing for sure is that in the
last two or three years they have been appearing in more months than
previously,” he added.
The jellyfish, which were introduced to the
Mediterranean through the Suez Canal 29 years ago, used to only appear in June
through September, as well as February and March, but in the past few years they
have had a significant presence year-round, according to Spanier.
Levant Basin of the eastern Mediterranean is “the only place on earth with four
alien-scyphozoan jellyfish concurrently,” all of whom migrated from the Suez,
When the jellyfish come in “big concentrations,” scientists
have found that there are often accompanying “big concentrations of rubbish...
which is another problem that we suffer from,” Spanier explained.
said that there are many different reasons for the jellyfish explosion – both in
Israel and worldwide – including global warming, which has increased sea
temperatures significantly and provides a good environment for jellyfish, but
less so for other species.
“Also, over-fishing, which is very clearly
happening along out coast, can [eliminate] potential predators of the jellyfish
that are a protective unit,” Spanier added. “These jellyfish have unbelievable
reproductive potential. They can reproduce throughout the year...and they
spawn hundreds of thousands of eggs.”
Galil agreed, noting that
Mediterranean fish stocks are in decline and that “once jellyfish become
dominant in a region, annual cycles of strong jellyfish production may inhibit
the revival of some depleted fish stocks since they routinely compete for
plankton prey with juvenile, and many adult, pelagic fish.”
As far as the
future of the season goes, none of the scientists were able to predict what
Israelis – and their power stations – should expect in the coming months.
However, only a few years ago a similar problem closed the large Ashkelon power
“There is no rule on the behavior of the jellyfish,” Glazer said.
“The power plant wishes to know the future because they want to be ready for
such an attack.”