The shortcut between two seas has driven intruders to the Mediterranean shores that push out local species and make life miserable for swimmers
Zafrir Rinat | Nov. 17, 2019 | 1:09 PM

This week 150 years ago a group of notables that came to Egypt from several European countries made its way through the new canal that connected the Mediterranean with the Red Sea for the first time. To the strains classical music,” they celebrated the opening of the project known as the Suez Canal. This impressive feat of engineering did, as anticipated, usher in a revolution in the movement of goods and people through the region. What the planners didn’t foresee, however, was that it would make the Mediterranean Sea fall victim to a drastic ecological change brought on by the invasion of hundreds of species from the Red Sea.

This migration process caused far-reaching changes for the local fauna. Its implications could worsen in wake of the canal’s expansion over the last decade. The climate crisis is causing the water temperature in the Mediterranean to rise, further enhancing conditions for the invaders, which are better suited to these changes.

According to the latest estimates, there are 440 different invasive species in the Mediterranean that came from the Red Sea. The number includes a wide range of creatures: fish, crabs, clams and, of course, jellyfish. Dr. Bella Galil of Tel Aviv University’s Steinhardt Museum of Natural History says that Israel’s beaches are the only place in the world where one can find five invasive species from a group called Scyphozoa (also known as True Jellyfish).

Galil was the first to scientifically identify the presence of the nomad jellyfish – the bane of Israeli beachgoers – in the Mediterranean. She was one of the speakers at a conference at the National Academy of Sciences in Jerusalem last week to mark the 150th anniversary of the opening of the Suez Canal.

The invasive species are systematically pushing out the local species and altering the ecosystem. The Mediterranean shrimp, a long-time favorite of fishermen, has disappeared; an invasive species has taken its place. A significant portion of the Mediterranean’s snail and clam populations have been replaced by invasive species. Various fish species, including red mullet, are dwindling and vanishing from the Mediterranean. And recent reports say the lionfish, which is poisonous and dangerous to humans, is rapidly spreading.

The prevalence of invasive species is detailed in the latest report from the Mediterranean Sea Monitoring Program, run by the Israel Oceanographic and Limnological Research Institute for the Environmental Protection Ministry. According to the report, which covers 2017, about half of the mollusks that were collected as part of the monitoring program belonged to invasive species. Two other types of invasive fish species that had not been previously observed were also identified. Not all of the invasive species survive over time, and major shifts often occur in the size of their populations. But their presence remains prominent and extensive.

The invasion has gotten worse in recent years due to the enlargement and deepening of the Suez Canal. Species that live in deeper waters were previously unable to traverse the canal, but now they can. The gradual warming of the Mediterranean Sea due to climate change is also helping to boost these invasive species, since they are more suited to the higher temperature. As a result, the invasion is expanding to more areas of the sea.

“The massive enlargements of the Suez Canal, and an increase in temperature and salinity of Mediterranean seawater, confer advantages to Erythraean [Red Sea] newcomers, and they are more likely to enter, establish viable populations and spread into new habitats. Invasion is fast and irreversible,” says Galil.

Clogged with jellyfish

Besides their ecological impact, the invasive species also cause economic harm. Jellyfish are drawn into power stations and desalination plants along with the water, clogging them up. “Each year, the large swarms of nomad jellyfish cause a slowdown in the power stations’ activity and a disruption of the desalination process,” wrote Dr. Tamar Lotan of the University of Haifa in the most recent annual Maritime Strategic Evaluation published by the university. “From the limited figures we have, it appears that these disruptions have not yet caused major economic damage. However, since Israel depends on the full electricity output from the power stations on the coast and relies primarily on desalination to produce drinking water, an effort on the national level to find a biological-engineering solution to prevent the jellyfish from being drawn into the machinery is advisable.”

Israel and other countries have been making efforts to cull certain species like the lionfish through fishing. But the Mediterranean’s ecosystem can never be restored to what it once was, and the invasive species will still be there in the future. Still, certain preventive actions can be taken to make the sea less welcoming for the invaders. One of these is to preserve the natural habitats where local species flourish to the greatest extent possible.

“Protecting habitats can slow down the establishment of the invasive species,” says Dr. Dror Zurel of the Environmental Protection Ministry’s Marine Monitoring and Research Center. “Overfishing, pollution and destruction due to infrastructure construction are factors that encourage invasive species to establish viable populations. We are working together with the Nature and Parks Authority to promote the designation of marine nature reserves. Through the planning committees, we are calling for surveys to be conducted to identify ecologically sensitive areas and find ways to protect them. For example, planning for the location of the brine disposal facility [for the salt that is left over after the desalination process] was done after studying a pollutant diffusion model to ensure that the brine cloud did not reach sensitive habitats.

“During construction work at the Haifa port, buoys were installed to measure the murkiness of the seawater near sensitive habitats. When the findings exceeded scientists’ recommendations, the excavation work was halted. Indirect protection of the local marine life is achieved by reducing the amount of sewage that flows into the sea. The committee headed by the ministry that issues permits to industrial plants for the discharge of waste has brought about a reduction of over 95 percent in pollutants compared to three decades ago.”

Galil believes the invasive species can be somewhat deterred from reaching the Mediterranean by means of a salinity barrier. This could be done in conjunction with the planned construction of desalination plants near the Suez Canal as part of Egypt’s major development program for the area.

“The Egyptian government is in the position to reduce future incursions by using the brine effluents from the desalination plants being built in the canal zone to restore the salinity barrier once posed by [Egypt’s] Bitter Lakes,” says Galil, adding that “the canal was built by man and man could also reduce the intensity of the incursion and its impact on the marine environment, the economy and human health.”