The Adriatic Sea hosts diverse marine ecosystems with rich biodiversity and unique ecological dynamics. These ecosystems are influenced by complex coastal habitats and open waters, supporting a range of species and contributing to the region's ecological and economic significance. This study projects the future climate-induced oligotrophication of the Adriatic marine ecosystems. A high-resolution biogeochemical model was developed, forced by climate projections from 1992 to 2050 under RCP8.5. The model evaluated changes in ecoregions with different trophic conditions, identified using k-medoid classification. The results indicate a generalized oligotrophication of the basin, especially in the northern estuarine areas, driven by a significant decrease in river discharge from the Po Plain. This scenario, combined with ongoing warming, salinization, and acidification, raises concerns about the long-term resilience of the Northern Adriatic food web. The study provides stakeholders with insights into how potential long-term decreases in river discharge could affect the marine ecosystem and its services. The model's results show a decline in chlorophyll-a, phytoplankton biomass, and net primary productivity in key ecoregions, with the most significant declines in the Northern Estuarine area. The study highlights the importance of river discharge in maintaining nutrient-rich conditions and the potential threats to the Adriatic ecosystem from climate change and human activities. The findings underscore the need for monitoring and managing the Adriatic Sea's ecosystems to ensure their sustainability in the face of ongoing environmental changes.The Adriatic Sea hosts diverse marine ecosystems with rich biodiversity and unique ecological dynamics. These ecosystems are influenced by complex coastal habitats and open waters, supporting a range of species and contributing to the region's ecological and economic significance. This study projects the future climate-induced oligotrophication of the Adriatic marine ecosystems. A high-resolution biogeochemical model was developed, forced by climate projections from 1992 to 2050 under RCP8.5. The model evaluated changes in ecoregions with different trophic conditions, identified using k-medoid classification. The results indicate a generalized oligotrophication of the basin, especially in the northern estuarine areas, driven by a significant decrease in river discharge from the Po Plain. This scenario, combined with ongoing warming, salinization, and acidification, raises concerns about the long-term resilience of the Northern Adriatic food web. The study provides stakeholders with insights into how potential long-term decreases in river discharge could affect the marine ecosystem and its services. The model's results show a decline in chlorophyll-a, phytoplankton biomass, and net primary productivity in key ecoregions, with the most significant declines in the Northern Estuarine area. The study highlights the importance of river discharge in maintaining nutrient-rich conditions and the potential threats to the Adriatic ecosystem from climate change and human activities. The findings underscore the need for monitoring and managing the Adriatic Sea's ecosystems to ensure their sustainability in the face of ongoing environmental changes.