A sea where the rules no longer apply
Cyprus fisheries now see nets filled predominantly with lionfish, an invasive species absent from local markets. The red mullet that once made up a large portion of catches has nearly disappeared. 'The Mediterranean of our grandparents is lost forever,' says Ernesto Azzuro, a marine biologist who has been monitoring the region's drastic changes. 'These changes are irreversible.'
The Mediterranean is warming at a faster pace than most other seas, with scientists predicting a 2 to 6°C rise in temperature by 2100. Because it is an enclosed basin, it can't release heat as effectively as open ocean environments, leading to a greenhouse-like effect in the water. As a result, invasive species from the Red Sea—introduced via the Suez Canal—are flourishing, while the native fish populations are struggling to survive in the altered environment.
Fishing traditions under siege
Among the most concerning invasive arrivals are lionfish, spotted puffers, and rabbitfish. The lionfish, for example, was first recorded in the eastern Mediterranean in 2012. It has since moved westward, replacing red mullet and other traditional catches. 'We are losing what makes this sea unique,' says Piero Genovesi Papik, a zoologist based in Italy.
The Adriatic region has seen the collapse of its mussel industry, driven by temperatures that have frequently exceeded 30°C. 'The die-off was spectacular,' Azzuro remarks. Mussels are especially vulnerable to high temperatures, and without the development of resilient new populations, their future in the Adriatic remains uncertain.
What can be done when it's too late?
Experts are attempting to minimize the damage. Some invasive species, like lionfish, are being marketed at high prices in specific regions. Others, such as the toxic pufferfish, are being incinerated. However, these solutions remain temporary and fragmented. 'It’s too late to reverse the spread,' says Papik. According to him, the solution is to prevent the introduction of more species by treating ballast water in ships, a practical step that could reduce the arrival of new invaders by 95 to 99 percent.
A public awareness campaign titled 'Beware of those four' has been initiated to inform the public about the risks these fish pose to human health. Lionfish's spikes can lead to intense pain, while pufferfish are potentially deadly if not prepared correctly. Yet, despite these awareness efforts, many fishers haven't adapted their methods, and invasive species continue to spread unchecked.
A changing marine landscape
Azzuro reports that over 1,000 invasive species have been identified in the Mediterranean, with 800 of them having become permanently established. The transformation is dramatic. He notes that in the shallows of the eastern Mediterranean, 93 percent of the mollusk population has been lost. Once teeming with mussels, the Adriatic has seen nearly all its mussel population die out due to extreme sea temperatures.
Without finding populations that can withstand these changing conditions, the future for mussels in the Adriatic looks grim.
A global challenge demanding joint action
Papik, the zoologist, asserts that 'we know what needs to be done—we should reduce the use of fossil fuels.' He adds that this is an urgent issue for the entire human race. Although the solutions are known, they require a global and unified approach. 'It’s an urgent matter for humanity,' Papik emphasizes. 'But of course they require a global and joint vision.'
Azzuro's institute and its partners launched the 'Beware of those four' campaign several years ago to heighten awareness about the risks invasive species pose to human health. For example, pufferfish can be toxic and potentially fatal if consumed by humans. The lionfish’s poisonous spines can cause serious harm to anyone who gets stung.
Scientists are now considering how coastal communities can adapt to these changes. One method is to market invasive species that are edible. Azzuro notes that some species, such as the lionfish, provide clear economic advantages since they are sold at high prices in certain countries.
Papik states that although it is 'too late' to reverse the spread of invasive species in the Mediterranean, there are practical steps to lessen their impact. 'This is something that is technically doable and that can reduce the number of new species coming into the region,' he asserts.