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Marmara - A Sea Running Out of Breath

January 2, 2026

Turkey's Sea of Marmara is on the brink of environmental collapse.

DW | Nahaufnahme | 2026 | Erstickt das Marmarameer? | Ökologische Krise im Marmarameer
Image: Kobalt Documentary GmbH

Pollution, overfishing and climate change are depleting its oxygen. The crisis became visible when a thick layer of algal slime first began spreading across its waters in 2021.

Image: Stephan Talneau/DW

Necla Köseoğlu, from Rumelikavağı, is one of the last people still working in traditional small-scale fishing on Turkey's Sea of Marmara. She's also one of the few women in the business. She used to be able to live off what she made from fishing, but those days are gone. Fish stocks in the Turkish inland sea have declined dramatically. The ecosystem is at risk of collapse due to overfishing, urban and industrial waste, and shipping pollution. The Marmara Sea, whose shores are home to around 25 million people, is suffocating.

Image: Kobalt Documentary GmbH

The crisis became widely known in 2021, when a kind of slime known as "sea snot" began to cover large parts of the sea's surface. The foul-smelling, gelatinous substance is an organic substance secreted by algae. It's not harmful to humans, but it starves other marine life of oxygen. Professor Hasan Örek is among the marine biologists and oceanographers sounding the alarm.

Image: Stephan Talneau/DW

Istanbul's city government has acknowledged the looming disaster. Environmental engineer Ayşen Erdinçler and her colleague Ilker Aslan say stricter controls and fines will curb pollution from shipping. But those measures are nothing more than a drop in the ocean. The greatest threat comes from millions of cubic meters of untreated domestic and industrial waste discharged into the sea each day. Local wastewater treatment plants urgently need modernization, but the Turkish government lacks the funds to carry it out.

 

 

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