Lost Forever: Mediterranean’s Future with Invasive Species

A Sea Transformed by Climate Change

Poinews.com – Lost forever is how marine scientists describe the Mediterranean of our ancestors. Climate change, driven primarily by fossil fuel combustion, is heating the Mediterranean Sea and introducing hundreds of invasive fish species that are decimating indigenous populations. As biodiversity declines, coastal communities face mounting challenges maintaining their traditional livelihoods.

“The Mediterranean of our grandfathers, of our elders, and of the Greeks, of ancient Greece is lost forever. So many of those changes are irreversible,” explains Ernesto Azzuro, a marine biologist with the Italian National Research Council’s Institute for Marine Biological Resources and Biotechnology. Researchers have classified the Mediterranean as a climate change “hot spot,” projecting water temperatures will rise between 2 and 6 degrees Celsius by 2100.

Heatwaves are projected to intensify and occur more frequently, according to the Mediterranean Experts on Climate and Environmental Change, an independent scientific network. Ronan McAdam, an oceanographer at the Euro-Mediterranean Center on Climate Change, notes that the sea’s enclosed basin structure prevents heat from dissipating as it does in open oceans. These warming waters have created an attractive habitat for invasive species such as the spotted puffer fish, described by Azzuro as a voracious predator and the “worst invader.”

Ecological and Economic Consequences

These invasive species are now advancing toward France and Spain after entering through the Suez Canal. The UN food and agriculture body’s General Fisheries Commission for the Mediterranean reports that while such species have existed for decades, their proliferation accelerated following the early 2000s, coinciding with rising sea temperatures. The lionfish, for instance, was first documented in the eastern Mediterranean in 2012 and has since expanded rapidly westward.

“The Mediterranean will be even poorer, even with less species, simply because climate change is really making this part of the Mediterranean, especially the eastern part of the Mediterranean, really unsuitable for native species,” Azzuro observes. Cyprus, positioned close to the Suez Canal, was the first to experience these invasive fish impacts. Lionfish displaced indigenous stocks like the red mullet, disappointing fishers whose local varieties had long been customer favorites.

Rabbitfish present another threat, consuming algae from the sea floor and destroying habitats for numerous indigenous species. “We know what should be done. We should reduce the use of fossil [fuels],” states Piero Genovesi Papik, a zoologist with Italy’s Higher Institute for Environmental Protection and Research.

“But that’s definitely an urgent matter for the humanity, and we all know the solutions, but of course they require a global and joint vision.”

Azzuro reports that approximately 1,000 invasive species have been identified in the Mediterranean, with 800 now firmly established. The transformation is dramatic. According to Azzuro, the shallows of the eastern Mediterranean have lost 93 per cent of their mollusk population.

Along the Adriatic coast, once teeming with mussels, nearly all have perished due to sea temperatures that occasionally surpassed 30 degrees Celsius. From Venice in the north to Bari in the south, “the die-off was spectacular,” he notes. “Unless we… find populations able to survive through these different climates, the future of mussels is not a happy future, at least in the Adriatic Sea.” Azzuro mentions that his institute and partners launched the ‘Beware of those four’ campaign several years ago to highlight the dangers invasive species pose to human health.

For example, puffer fish is toxic and potentially lethal if consumed by humans. The lionfish’s poisonous spikes can cause severe injuries to anyone stung. Scientists are actively exploring how coastal communities can adapt.

One solution involves commercializing edible invasive species. Another strategy pays fishers to capture inedible species like the puffer fish for incineration. Some species, such as the lionfish, offer “clear economic benefits because it’s sold at very high prices, especially in some countries,” Azzuro explains.

However, fishers have not fully exploited the invasive dusky spinefoot, whose population has surged in Italian waters. Papik, the zoologist, acknowledges that while it is “too late” to reverse the spread of invasive species in the Mediterranean, practical mitigation approaches exist. The first involves preventing further migration by enforcing an international treaty requiring national authorities to treat ballast waters in incoming ships that may transport such species.

“This is something that is technically doable and that can reduce the number of… new alien species by 95 to 99 per cent,” he states. Another approach involves treating ship hulls with specialized paint that prevents unwanted hitchhikers from attaching themselves.