With Waters at 32C, Mediterranean Tropicalization Shifts into High Gear
Once considered a boundary to warm-water marine species, the Mediterranean Sea is undergoing a transformative change due to rising temperatures. This phenomenon, aptly described as ‘tropicalization’, sees warm-water species from the Red Sea comfortably settling into the Mediterranean environment, significantly altering the local marine ecosystem.
A case in point is a recent scuba diving excursion off the coast of Antalya, southern Turkey. Murat Draman, a diving instructor, noted an unprecedented water temperature of 29C at a depth of 30 meters. Temperatures that typically peaked at 25C in August now soar to nearly 32C, painting a clear picture of the Mediterranean’s accelerated warming trend.
This warming trend has encouraged a variety of Red Sea species to migrate through the Suez Canal, invading the eastern Mediterranean and redefining its biodiversity. One such newcomer is the lionfish (Pterois miles), which was once a rare sight but is now common. Featuring striking spotted fins, the lionfish has become a dominant predator, drastically reducing populations of smaller fish like gobies, which were once abundant in the area.
The repercussions of these newfound invasions are felt most acutely in the eastern Mediterranean, the warmest part of the sea and the region experiencing the fastest temperature increases. Professor Gil Rilov from the Israel Oceanographic and Limnological Research institute underscores the gravity of the situation. With the recent deepening and widening of the Suez Canal, an influx of species takes root every year. This makes for an environment in which native species find themselves ill-suited to compete, leading to their possible disappearance.
Unfortunately, the changes seen in the east are likely to encroach upon the northern and western parts of the Mediterranean in the coming years. Species like the rabbitfish (Siganus rivulatus), first observed off the coasts of Türkiye, Lebanon, and Israel, are making their way westward and have even been spotted near Malta, over 1,000 miles from the Suez Canal.
Last month’s data revealed by scientific research indicates that July marked the warmest on record for the Mediterranean, with sea surface temperatures averaging 26.68C—a figure raising alarm among ecological experts.
Looking ahead, there’s a concern that the tropicalization trend could penetrate further through the Strait of Gibraltar into the wider Mediterranean basin. A study envisages scenarios where the warming Atlantic Ocean could facilitate species movements from the West African coast into the western Mediterranean as soon as 2050. By the year 2100, a more severe outlook could see the Mediterranean entirely tropicalized should current climate trends persist.
To mitigate these ecological disruptions, measures must be put in place. Draman emphasizes the importance of maintaining species like lionfish away from protected marine areas to conserve biodiversity. He notes the absence of natural Mediterranean predators that could otherwise check the population growth of these species. In the Red Sea, predators such as sharks and barracudas naturally control the lionfish population—an ecological balance lacking in the Mediterranean.
In conclusion, the Mediterranean’s tropicalization underscores the need to monitor and respond to climate change-induced ecological shifts actively. The increase in non-native species demands urgent attention to preserve the unique marine diversity and ecological integrity of this historically temperate sea.
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