Bringing it all together - an integrated, unifying approach to addressing challenges in estuarine management

Transitional ecosystems such as estuaries are highly dynamic, subject to multiple human pressures that can alter their structure and functioning. This study applied a cumulative effects method together with a cause-consequence-response framework to the Mondego estuary (Portugal) to evaluate cumulative impact risks (IR) associated with human activities across ecological components. Transport, extraction and cultivation of living resources, water management and urban and industrial activities were identified as the main sectors generating pressures, including physical loss, introduction of non-indigenous species, nutrient enrichment, introduction of synthetic compounds, smothering and litter. Transport, particularly shipping and associated infrastructure, exhibited the highest potential IR, largely through habitat modification and potential introduction of non-indigenous species. Extraction and cultivation sectors mainly affected littoral biogenic habitats and the water column through nutrient and organic matter enrichment. Cluster analyses revealed two main pressure domains: (i) water-mediated influencing pelagic and mobile fauna and (ii) habitat-specific affecting benthic and shoreline components. Comparisons with elsewhere showed that cumulative and historical disturbances, such as channelisation and dredging, continue to shape the ecosystem conditions over decades. Unifying both frameworks provided complementary insights linking human drivers, activities, pressures and ecological responses, while identifying priorities for estuarine restoration and integrated management. These quantified ecological responses to cumulative pressures and management through restoration potential and more effective governance and management.