United News of Bangladesh

The Mediterranean Sea is undergoing major changes as rising temperatures linked to climate change create favorable conditions for hundreds of invasive species, threatening native marine life and the livelihoods of coastal communities. Scientists say the warming is largely driven by climate change caused by the burning of fossil fuels such as oil, coal and gas. “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,” said Ernesto Azzuro, a marine biologist at the Italian National Research Council’s Institute for Marine Biological Resources and Biotechnology. The Mediterranean is considered a climate change “hot spot,” with scientists predicting that its waters could warm by 2 to 6 degrees Celsius (3.6 to 10.8 degrees Fahrenheit) by 2100. Marine heat waves are also expected to become more frequent and severe. Ronan McAdam, an oceanographer with the Euro-Mediterranean Center on Climate Change, said the Mediterranean is particularly vulnerable because it is an enclosed sea, meaning heat cannot escape as easily as it does in the open oceans. The warmer waters are helping invasive species such as the spotted puffer fish expand their range. Azzuro described the species as a highly aggressive predator and one of the Mediterranean’s “worst invaders.” Many of these species entered the Mediterranean through the Suez Canal and are now spreading toward France and Spain. The U.N. Food and Agriculture Organization’s General Fisheries Commission for the Mediterranean said invasive species have been present in the region for decades, but their spread accelerated after the early 2000s as sea temperatures increased. Lionfish, for example, were first recorded in the eastern Mediterranean in 2012 and have since rapidly spread 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 said. Cyprus was among the first countries to experience the impact because of its location near the Suez Canal. Lionfish have reduced populations of native fish such as red mullet, affecting fishers who depend on popular local varieties. Rabbitfish are also causing problems by feeding heavily on algae on the seabed, damaging habitats that are important for native species. “We know what should be done. We should reduce the use of fossil (fuels),” said Piero Genovesi Papik, a zoologist with Italy’s Higher Institute for Environmental Protection and Research. “But that's definitely an urgent matter for humanity, and we all know the solutions, but of course they require a global and joint vision,” he said. About 1,000 invasive species identifiedAzzuro said around 1,000 invasive species have been identified in the Mediterranean, with about 800 of them now firmly established. The impact is already severe. Shallow waters in the eastern Mediterranean have lost about 93% of their mollusk population, he said. Along the Adriatic coast, mussels that were once plentiful have nearly disappeared as water temperatures have at times climbed above 30 degrees Celsius (86 degrees Fahrenheit). “Unless we … find population able to survive through these different climates, the future of mussels is not a happy future, at least in the Adriatic Sea,” Azzuro said. Azzuro’s institute and its partners also launched a campaign several years ago called “Beware of those four” to warn people about invasive species that can pose risks to human health. Puffer fish, for example, are toxic and can be deadly if eaten, while lionfish have venomous spines that can cause serious injuries. Experts seek ways to limit damageScientists say the spread of invasive species in the Mediterranean cannot now be fully reversed, but steps can be taken to reduce their impact. One option is to promote the commercial fishing and sale of invasive species that are safe to eat. Another is to provide incentives for fishers to catch species such as puffer fish that cannot be consumed, allowing them to be safely destroyed. Some invasive species, including lionfish, can have economic value because they fetch high prices in some markets. However, fishers have not yet made much use of the dusky spinefoot, whose numbers have increased significantly in Italian waters. Papik said it is now “too late” to completely reverse the spread of invasive species, but practical measures can still limit further damage. One important step is to prevent new species from entering the Mediterranean by enforcing an international agreement requiring ships to treat ballast water before entering the region. Such water can carry marine organisms from one part of the world to another. “This is something that is technically doable and that can reduce the number of ... new alien species by 95 to 99%,” Papik said. Another measure is using special coatings on ship hulls to prevent marine organisms from attaching themselves to vessels and spreading to new areas. Fishing rules are also being revised to help native species recover. In some areas, experts are considering encouraging the growth of native mollusks that are more resistant to invasive species such as the blue crab. “In the coming years, I think that the challenge will be to restore, to find new ways to restore the environment,” Papik said.