Natural and anthropogenic pressures drive coastal eutrophication worldwide, depending on the system's physical and biogeochemical dynamics in multiple spatial and temporal scales. Understanding the complexity of this process is essential to support management efforts and sustainability. Nutrients load to the Bay of Santa Catarina Island (BSCI), an important area for mollusc aquaculture, fisheries and tourism in Brazil, were assessed to identify the pressures of the eutrophication process. An updated Driver-Pressure-State-Impact-Response framework was used to facilitate the understanding of the relationship between human activities and impacts on human welfare. Pressures from runoff and effluents from combined sources resulted in inputs of 1998 t N.year⁻¹ and 155 t P.year⁻¹ to the system. The watersheds were characterized as meso-active to eury-active for both N and P yields. In addition to the local anthropogenic pressures, meso-scale events, such as the seasonal influence of the Plata Plume River, act as an external source of nutrients, sometimes associated with harmful algae bloom events. The results show that eutrophication and its symptoms could impact 85% of the ecosystem services of the region. Management of eutrophication at BSCI requires integrated actions between the nine municipalities of the watershed, but there are obstacles in environmental legislation and political interest to promote it. This study provides the scientific basis for stakeholders and decision-makers to establish priorities and actions in coastal municipalities to minimize eutrophication.

自然和人为压力驱使全球沿海富营养化，这取决于系统在多个时空尺度上的物理和生物地球化学动态。了解此过程的复杂性对于支持管理工作和可持续性至关重要。评估了圣卡塔琳娜岛湾（BSCI）（巴西软体动物水产养殖，渔业和旅游业的重要区域）的营养负荷，以确定富营养化过程的压力。使用了更新的“驾驶员-压力-状态-影响-响应”框架来促进对人类活动与对人类福利影响之间关系的理解。来自径流的压力和来自综合来源的废水导致的投入分别为1998 t N.year ^-1和155 t P.year ^-1到系统。对于N和P的产量，分水岭的特征是中等活性到中等活性。除当地人为压力外，中尺度事件（例如普拉塔羽河的季节性影响）是营养的外部来源，有时还与有害的藻类开花事件相关。结果表明，富营养化及其症状可能影响该地区85％的生态系统服务。BSCI的富营养化管理要求在该流域的9个市镇之间采取综合行动，但是在环境立法和促进该立法的政治利益方面存在障碍。这项研究为利益相关者和决策者在沿海城市建立优先事项和采取行动以最大程度地减少富营养化提供了科学依据。