Documenting the emergence of a new mucilage formation in the Sea of Marmara in 2024

Mucilage represents a significant environmental disaster in marine ecosystems, with the potential to leave permanent effects on biodiversity. In this study, we document the first mucilage formation of the year detected in the Gulf of Erdek, south of the Sea of Marmara (SoM), on October 23, 2024. Our findings align closely with historical data, reinforcing the trend of increasing mucilage events in the region. Field studies revealed sea surface temperatures reaching 21.2 °C, well above seasonal norms, indicating thermal anomaly. Due to insufficient water flow and vertical mixing, the thermocline layer could not be observed until it reached 28.4 m, resulting in consistent temperatures ranging from 19.6 °C to 21.2 °C. Furthermore, primary production remains alarmingly high, with nutrient inputs in the SoM exceeding natural capacities, as evidenced by chlorophyll levels of 2.4 mg/m³. Anthropogenic factors, including domestic, industrial, and agricultural wastes, create a persistent substrate for mucilage formation, exacerbated by temperature anomalies and stagnant water conditions. If these trends continue, mucilage could continue to be a persistent environmental hazard in the SoM. Thus, while treatment remains the most viable solution for waste reduction, urgent and comprehensive measures are essential to mitigate this growing threat to the marine ecosystem.