A viscous foam has invaded the coast of northwestern Turkey for several weeks under the combined action of pollution and global warming, a phenomenon that worries conservationists.
Mucilages, sometimes nicknamed “sea snot”, appear when plant organisms living in suspension in water swell to form a kind of yellowish mucus that covers large areas of the sea.
In addition to the inconvenience for residents and fishermen, the mucilages pose above all a danger for the ecosystem, in particular by blocking sunlight and depriving the underwater flora and fauna of oxygen.
The sheets of mucilages have multiplied in recent weeks in the Sea of Marmara, including in Istanbul, the economic capital of Turkey.
This natural phenomenon was first recorded in Turkey in 2007. But the current invasion is by far the largest to date.
According to specialists, it is due to pollution and warming temperatures, which promote the proliferation of plant substances at their origin.
“The mucilages cover the surface of the sea like a sheet. After a while, it sinks into the water and covers the “marine ecosystem, poisoning molluscs and crustaceans,” Muharrem Balci, professor of biology at Istanbul University, told AFP. “If this process is not stopped, a rotten egg smell will appear” soon, he emphasizes.
The invasion of mucilages could last all summer if urgent measures are not taken, alarms Cevahir Efe Akçelik, environmental engineer and secretary general of the Union of Chambers of Engineers and Architects of Turkey.
“Studies show that the mucilages are no longer only on the surface, but also at depths of 25, 30 meters,” he told AFP.
The Sea of Marmara, which stretches from Istanbul to the Aegean Sea, is bordered by areas that are among the most populated, industrialized and polluted in Turkey.
The problem is aggravated by the high pollution of the Danube, a river that flows into the Black Sea, which is connected to that of Marmara by the Bosphorus Strait.
The Turkish authorities have deployed trawlers to drain the viscous substances, but experts believe that these means are insufficient.
For Mr. Balci, it would be necessary in particular that the coastal cities coordinate their actions and that the substances released into the sea by the factories are better treated.