A rare marine ecosystem of endangered pina shellfish and seagrass has been discovered off Istanbul’s Tuzla coast, surprising scientists and prompting plans for a permanent monitoring station in one of the most industrialized parts of the Marmara Sea.
The ecosystem, found during dives along the heavily urbanized Tuzla shoreline, includes healthy populations of Pinna nobilis — known as the noble pen shell, or pina — living within seagrass meadows, a combination researchers described as remarkable given the environmental pressures in the area.
Endemic to the Mediterranean, pina is one of the world’s largest bivalve species, capable of growing up to 120 centimeters and living for as long as 50 years. The species plays a critical ecological role by filtering around 6 liters of seawater per hour, improving water quality and supporting marine life at depths of up to 60 meters.
Pina populations across the Mediterranean suffered a devastating collapse between 2016 and 2019 after a fast-spreading parasite wiped out colonies from the Dardanelles to the Strait of Gibraltar, pushing the species to the brink of extinction. Scientists now say the only healthy surviving population remains in the Marmara Sea.
Beyond disease, the species faces growing threats from pollution, coastal landfills, bottom-trawling, anchoring and tourism.
The Tuzla discovery was made in January under the “PİNA-İZ” and “ÇAYIR-İZ” conservation projects, led jointly by the Environment, Urbanization and Climate Change Ministry and Bandırma Onyedi Eylül University, which monitor pina and seagrass habitats across the Marmara region.
Divers identified dense pina populations within a narrow 50-to-100-square-meter patch of seagrass near a pier, including both juvenile and adult specimens — evidence of an active and reproducing ecosystem.
Professor Mustafa Sarı of Piri Reis University said the discovery showed that natural habitats in the Marmara Sea were still resisting environmental pressure.
The Tuzla site will now be integrated into a long-term monitoring network, with regular dives planned to track seagrass growth, pina development, new juvenile recruitment and possible disease outbreaks. Researchers will also record environmental data, including water temperature, salinity and light penetration.
Sarı said seagrass meadows, often described as the “lungs of the sea,” support up to 40 times more marine biodiversity than areas without seagrass, making their protection vital for the future of the Marmara ecosystem.
