The study evaluates eutrophication intensity in coastal and offshore waters of the Black Sea using the Black Sea Eutrophication Assessment Tool (BEAST). From 2020 to 2022, data were collected from 68 stations across 617 water samples, analyzing nutrients, chlorophyll a, Noctiluca scintillans, and dissolved oxygen. Additionally, 179 zoobenthic and 251 phytobenthic samples were collected. Results show that coastal waters have higher nutrient levels and algal blooms compared to offshore waters, necessitating significant reductions in nutrient concentrations to achieve good environmental status. Transitional waters require a 55% reduction in inorganic phosphorus and 43% in inorganic nitrogen, while coastal waters need 38% and 37%, respectively. The study highlights the need for improved wastewater treatment, stricter agricultural runoff controls, and continuous monitoring. Effective ecosystem-based management strategies, integrated coastal zone management, and international cooperation are essential to mitigate eutrophication and promote the long-term health of the Black Sea ecosystem. The study provides new data on eutrophication in the Black Sea, emphasizing the need for evidence-based policies and collaborative initiatives to address the issue. The findings contribute to understanding the spatial variability and differential impacts of eutrophication within the Black Sea ecosystem. The study also underscores the importance of integrated approaches to assess and manage eutrophication, aligning with multiple Sustainable Development Goals (SDGs). The results indicate that coastal waters exhibit higher eutrophication intensity, with elevated nutrient levels, increased algal proliferation, and reduced transparency compared to offshore areas. The study concludes that targeted management strategies are critical to address coastal eutrophication and protect the health and sustainability of the Black Sea ecosystem.The study evaluates eutrophication intensity in coastal and offshore waters of the Black Sea using the Black Sea Eutrophication Assessment Tool (BEAST). From 2020 to 2022, data were collected from 68 stations across 617 water samples, analyzing nutrients, chlorophyll a, Noctiluca scintillans, and dissolved oxygen. Additionally, 179 zoobenthic and 251 phytobenthic samples were collected. Results show that coastal waters have higher nutrient levels and algal blooms compared to offshore waters, necessitating significant reductions in nutrient concentrations to achieve good environmental status. Transitional waters require a 55% reduction in inorganic phosphorus and 43% in inorganic nitrogen, while coastal waters need 38% and 37%, respectively. The study highlights the need for improved wastewater treatment, stricter agricultural runoff controls, and continuous monitoring. Effective ecosystem-based management strategies, integrated coastal zone management, and international cooperation are essential to mitigate eutrophication and promote the long-term health of the Black Sea ecosystem. The study provides new data on eutrophication in the Black Sea, emphasizing the need for evidence-based policies and collaborative initiatives to address the issue. The findings contribute to understanding the spatial variability and differential impacts of eutrophication within the Black Sea ecosystem. The study also underscores the importance of integrated approaches to assess and manage eutrophication, aligning with multiple Sustainable Development Goals (SDGs). The results indicate that coastal waters exhibit higher eutrophication intensity, with elevated nutrient levels, increased algal proliferation, and reduced transparency compared to offshore areas. The study concludes that targeted management strategies are critical to address coastal eutrophication and protect the health and sustainability of the Black Sea ecosystem.