Marine Stressors Magnified: Lessons from the Sea of Marmara Catastrophe

Marginal seas offer invaluable insights into the effects of human activities on marine ecosystems, often revealing localized impacts before they manifest in larger marine systems. The Sea of Marmara, a near-enclosed basin characterized by its natural permanent stratification, stands as a recognized biological corridor connecting the Mediterranean and the Black Seas. Surrounded by the densely populated and urbanized Marmara region, it encompasses the metropolitan city of Istanbul to the northeast—with a population approaching 20 million—and the Gulf of İzmit to the east, an epicenter of industrial activity. Consequently, over the past 35 years, the sea’s ecosystem has witnessed profound changes driven by the cumulative effects of overfishing, eutrophication, and its intrinsic permanent stratification. This reached a tipping point in 2021 with a basin-wide mucilage formation covering the sea’s surface for six months. Far from just an aesthetic disturbance, this event drastically hampered ecosystem functionality and caused notable economic setbacks. The Sea of Marmara exemplifies the human-induced pressures potentially facing other marine ecosystems, positioning it as a natural observatory for the stratified impacts anticipated from climate change.

Speaker: Dr. Nazli Demirel, Istanbul University

Dr. Nazli Demirel is a marine biologist with a focus on fisheries conservation and the ecosystem approach to fisheries management. She earned her PhD in marine biology from Istanbul University and later gained experience in fisheries conservation at GEOMAR, Germany, working closely with Dr. Rainer Froese on data-limited stock assessment methods. With 20 years of experience, she has contributed as a project coordinator, consultant, and expert to various fisheries management and ecosystem conservation projects both nationally and internationally. Since 2015, Nazli has been a senior researcher at the Institute of Marine Sciences and Management at Istanbul University. Her work primarily explores the state of marine ecosystems and fisheries resources in the Eastern Mediterranean, particularly under the influence of environmental stressors.