Climate change is driving mollusks extinct in the eastern Mediterranean

13 Januari 2021

If you want to see how climate change is already devastating fragile ecosystems, look no further than the eastern Mediterranean.

Many native species of marine flora and fauna on the coastline of Israel, one of the hottest areas in the Mediterranean Sea, are nearing their the very limits of their tolerance to increasing water temperatures. In fact, say experts at the University of Vienna in Austria, many of them can no longer cope with rising temperatures and are going extinct as a result.

“We predict that, as [the] climate warms, this native biodiversity collapse will intensify and expand geographically, counteracted only by Indo-Pacific species entering from the Suez Canal [in Egypt],” the experts warn in a new study published by the Royal Society in the United Kingdom.

The international team of researchers, led by Paolo G. Albano, an expert at the the University of Vienna’s Department of Paleontology, surveyed the extinction rate of native marine mollusks, which include snails, clams and mussels, along Israel’s coastline. They then compared the current populations of these marine creatures with their historical diversity by examining deposits of their empty shells on the seafloor.

What they found was a marked drop in the numbers of mollusks in the last few decades. Those at scuba diving depths have been affected the most as the researchers could not find any living individuals of as many as 95% of the species whose shells are present in the sediments.

Worse: most of the species that have managed to survive are unable to grow large enough to reproduce, which is “a clear sign that the biodiversity collapse will further continue,” according to Albano.

At the same time, tropical species that have been entering the area from the Suez Canal are now thriving in the warm waters in the Eastern Mediterranean a the expense of native species. “They occur in large populations and their individuals are fully fit to reproduce,” the scientists report.

“For anyone accustomed to snorkel or dive in the Mediterranean, the underwater scenario in Israel is unrecognizable: the most common species are missing, while in contrast tropical species are everywhere,” Albano summarizes.

And as the sea water will continue to warm, a further collapse of native biodiversity collapse will inevitably follow in the area and elsewhere around the eastern Mediterranean region. “Only intertidal organisms, which are to some extent pre-adapted to temperature extremes, and habitats in deeper water, where the temperature is markedly lower, will continue to persist – at least for some time,” the scientists say.

The only hope for much of native biodiversity of the Mediterranean Sea region at large lies in our continued effort to curb carbon emissions so as to keep climate change in check, the scientists explain.

“[T]he future is dim unless we immediately act to reduce our carbon emissions and to protect marine habitats from other pressures which contribute to biodiversity loss,” Albano stresses. “The changes that already occurred in the warmest areas of the Mediterranean may not be reversible, but we would be able to save large parts of the rest of the basin.”

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