The Mediterranean Sea is among the world’s great environmental jewels. The sea is highly saline, almost entirely enclosed by land and contains immense biodiversity. Scientists have long worried that its health is imperiled. Swelling coastal populations and ship traffic have brought overfishing and pollution. Climate change threatens to roil the waters still further.
One threat that is now gaining particular attention: the arrival of invasive species. One of the Mediterranean’s few outlets is the 146-year-old Suez Canal, which links it to the Red Sea and the ocean beyond. This creates a vital shipping route between Europe and Asia. But scientists fear that an expansion of the canal could bring more invasive species to the Mediterranean’s fragile waters.
Last year, Egypt announced plans to quickly build another waterway 45 miles long — essentially a parallel canal — so that ships can pass through more quickly than they do now. Often, they must wait because the channel is narrow — about 1,000 feet wide at its slimmest point.
Because of the Suez and its expansion, the Mediterranean Sea’s problem with invasive species is becoming “worse than anywhere else on earth,” said Bella Galil, a senior scientist with Israel’s National Institute of Oceanography.
Among the unpopular arrivals are venomous jellyfish, which have unnerved tourists and sometimes obstructed water intakes belonging to electric-power or desalination plants, in addition to harming the natural ecology. Another worrisome invader is the puffer fish, sometimes known as the silver-cheeked toadfish, which releases a neurotoxin that can harm other fish and humans who consume it.
The existing Suez Canal has already served as a conduit. Invasive species are particularly concentrated in the eastern part of the Mediterranean, in the vicinity of the Suez Canal. The canal is already seen as “as one of the most significant pathways of marine invasions globally,” and it has ushered more than 350 nonnative species — including the puffer fish — into the Mediterranean, according to a letter sent in December from Julia Marton-Lefèvre, then director of the International Union for Conservation of Nature, to Karmenu Vella, the European commissioner in charge of the environment, maritime affairs and fisheries.
Dr. Galil said, “Marine invasions are forever,” because it is impossible to remove an invasive species from the sea after it has arrived. The sea and its complex food web, she added, are “teetering.”
Some invasive species hitch rides in the ballast water of ships, an issue that the International Maritime Organization is trying to address through new rules regarding the treatment of ballast water to remove stowaways. Others cling to ship hulls, but many creatures simply swim through the Suez Canal itself.
“The expansion of the Suez Canal (enlarging, deepening) will make the environment within the canal more stable and thus will be easier to new species to cross it and invade potentially the Mediterranean,” Michel Bariche, an expert on Mediterranean marine issues at the American University of Beirut in Lebanon, said in an email.
Once they arrive, successful invasive species often outcompete natives, he said, because they tend to be more efficient at basic functions like obtaining food or reproducing.
Backers of the canal expansion cite strong economic opportunities. José Herrera, the parliamentary secretary for competitiveness and economic growth for the island nation of Malta, said that he expected the Suez expansion to benefit the Mediterranean region. “Having more traffic per se does not necessarily mean adverse effects,” he said. Malta, which lies along the major shipping lane through the sea between Europe and Asia, has been working to expand as a hub for shipping and logistics.
“Economic growth should always be promoted, but in sustainable ways,” Mr. Herrera said.
Dr. Galil said that the Suez project could learn from a similar expansion that is underway for the Panama Canal, which was built more than a century ago. The Panama Canal, she said, included an environmental impact assessment process that scientists participated in, and measures are in place to help prevent alien species from crossing between the Pacific and the Atlantic oceans.
“From a bio-invasion point of view, the Panama Canal is well run,” she said, noting that locks help prevent water transfers between the two oceans.
A study last fall in the journal Diversity and Distributions, however, has raised some concerns about increased opportunities for invasive species following the Panama Canal expansion.
But plans for the Suez continue unabated. Egypt is proceeding quickly with the expansion and has said, ambitiously, that it hopes to be done later this year.
The European Union is in touch with the Egyptian government about its plans, and watching closely. The environment, maritime affairs and fisheries arm of the European Commission is aware of the invasive species concerns, and has information suggesting that an environmental impact assessment is being carried out.
Solutions to the invasive species problem could include the establishment of a barrier of salty water, in combination with locks, that would discourage some species from swimming through to the Mediterranean.
The invasive species issues come atop other, mounting problems affecting the Mediterranean, such as overfishing and climate change. Because the Mediterranean is enclosed almost entirely by land, climate change especially could be tough on native species.
“It means that species that might change their distribution and move farther north have an upper boundary,” said Catherine Longo, a project scientist with the Marine Science Institute at the University of California, Santa Barbara.
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