Feature: Sea of Marmara struggling with biodiversity-threatening pollution

Without a comprehensive protection plan supported by stricter monitoring, the Sea of Marmara in northwestern Türkiye -- once a vibrant ecological gem -- could become an environment "where no marine life can survive," experts have warned.

ISTANBUL, Jan. 17 (Xinhua) -- Once a vibrant ecological gem teeming with corals, diverse marine life and unique underwater ecosystems, the Sea of Marmara in northwestern Türkiye now faces a growing pollution crisis fueled by untreated waste, industrial runoff and unchecked flow of pesticides from nearby farms.

"The Marmara Sea is characterized by two distinct currents: surface water from the Black Sea flows into the Aegean and deeper water from the Aegean flows toward the Black Sea," Murat Kapikiran, head of the Istanbul Chamber of Agricultural Engineers, told Xinhua.

"The surface water completes a full cycle every 6-7 months, while the deeper Aegean water takes 6-7 years to exit, creating a unique, slow-moving ecosystem," Kapikiran said.

However, pollution from deep-sea discharges lingers in the Marmara's deeper layers, with contaminants taking years to reach the Black Sea, slowly suffocating the fragile ecosystem there and threatening its survival.

A major contributor to the pollution is the Ergene Basin spanning three provinces in the Thrace region. The river basin used to be an important source of agricultural irrigation water and now hosts thousands of industrial facilities.

Water from the basin is now being pumped into the Marmara Sea at depths of 45-47 meters, further exacerbating the damage to the ecosystem, according to Kapikiran.

A dense layer of marine slime, or mucilage, has lately resurfaced in Marmara, raising severe concerns over a repeat of the 2021 crisis that nearly decimated marine life. Dives in various parts of the sea have revealed mucilage as shallow as 15 meters below the surface.

Sinan Isim, a 2-star diving instructor certified by the Turkish Underwater Sports Federation, said that pollution has led to a significant drop in oxygen levels and a rise in ammonia.

"The once vibrant biodiversity has diminished significantly," Isim observed. "The underwater that should be home to natural reefs now resembles abandoned buildings -- empty yet standing."

In 2021, Türkiye launched a 22-point action plan to address the mucilage problem. It initially helped reduce slime levels and improve the water quality, but failed to eliminate the threat.

Kapikiran considered a more comprehensive protection plan, supported by stricter monitoring, as essential to preserve the Marmara Sea's unique ecosystem.

"Otherwise, Marmara may reach a point where it's known for the smell of rotten eggs, becoming an environment where no marine life can survive," he warned.

In January, Türkiye's Ministry of Environment, Urbanization, and Climate Change launched a simultaneous inspection and monitoring effort across seven provinces along the Marmara Sea to reduce wastewater discharges. The initiative includes online monitoring of pollutants from 146 large wastewater treatment plants and ongoing sample collections for analysis.

Baris Salihoglu, director of the Institute of Marine Sciences at Middle East Technical University and a member of the Marmara Sea Action Plan Mucilage Science and Technical Committee, recently suggested that at least 30 percent of the Marmara Sea be designated as protected areas.

He also proposed a fishing ban in waters shallower than 80 meters and emphasized the need for the rehabilitation of river ecosystems to reduce pollutants entering the sea.■