Red Sea Resort Town Eilat Invaded by Notorious Sea Squirts That Could Harm Coral

Eilat is home to Israel’s one and only coral reef, which is quite the tourism magnet

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Ciona robusta has invaded Eilat
Ciona robusta has invaded Eilat Credit: Yaniv Shmuel

Yet another destructive invasive species has been discovered in the Gulf of Eilat: It’s a sea squirt, Ciona robusta, which feeds by filtering organic marine material and adheres to hard surfaces. That sounds innocuous enough, but the squirt is known for the damage it causes to ports in the Atlantic, its usual stomping ground, as well as the Mediterranean — and to coral reefs.

“The solitary ascidian Ciona intestinalis is among the most damaging of invasive fouling species in the world,” report the scientists who saw the thing, Noa Shenkar, Yaniv Shmuel and Dorothée Hucho.

Eilat is home to Israel’s one and only coral reef, which is quite the tourism magnet. The squirt was noticed during a survey of the Eilat marina and described in the journal Marine Biodiversity.

The unspectacular, semi-transparent beast was identified clinging to floating piers by Dr. Noa Shenkar, a zoologist with Tel Aviv University, her student Yaniv Shmuel and the help of Prof. Dorothée Huchon, also of TAU. The researchers suspect that it has entrenched itself in Eilat to the extent that it is already proliferating: “Periodical surveys revealed some of them with full gonoducts, and small individuals appeared two months later, indicating a reproductive population,” they wrote.

How it got to Eilat is a mystery. The researchers suspect the squirt hitched a ride on a boat that passed through the Suez Canal from the Mediterranean Sea. Typically, invasive species pass from the Red Sea to the Med through the canal, but in the case of said squirt, it went the other way.

Scientists have been warning that widening the Suez Canal, a major Egyptian infrastructure project, could enable even more invasive species to go back and forth between the Red and Med seas.

The impact of the sea squirt on the coral reef is more limited, because the reef is a particularly rich ecosystem with extensive competition among species. But if the state of the reef declines, or if there is a sudden influx of pollution that harms some of the coral species, the invading sea squirt can take advantage of the situation and multiply within the reef.

Sea squirts look innocuous enough, but they damage infrastructure. En masse, the soft-bodied animal can gum up conduits and pipelines, cling to ropes (making them heavy) and when they stick to boats, they can create drag.

The squirts are even the bane of oyster farms, not that Israel has any, points out Shenkar’s laboratory manager, Lion Novak, in conversation with Haaretz.

“Ciona is very common in the U.S.,” Novak says. “They specifically adhere to the shells of mollusks, not only infrastructure in ports.”

Now that they’re here, how can Eilat get rid of them? “That’s the million dollar question,” says Novak. “The squirts are an extremely successful invasive species. They establish themselves easily and drive out other species.”

The only hope lies in early detection, he says, but that doesn’t mean that anything can be done. “We don’t always have a solution,” Novak says. “The water is warming because of climate change. The Mediterranean has received hundreds of species from the Red Sea because of the Suez Canal.” One is the gorgeous but sadly poisonous lionfish. Now you can step on one and scream not only in the Indian Ocean or Red Sea but off the Mediterranean shores as well.

So can nothing be done? Australia, which is relatively rich in resources, had a sort of solution for invading sea squirts, Novak says: At enormous cost, they coated the marina infrastructure with squirt repellent. Not only is the initial outlay huge — so is the cost of maintenance. That wouldn’t work so well in Eilat.

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