The effect of land-based human activities is the most important driver of marine pollution and impact on marine ecosystems and coastal and marinedependent economies. The UNEP-Global Programme of Action (GPA) estimates that about 80% of the pollution load in the oceans originates from land-based activities, which threaten health, productivity, and biodiversity of the marine environment. The resulting impact of this pollution affects some of the most productive areas of the marine environment (ecologically and economically), such as estuaries and nearshore coastal waters. Linking watershed and coastal management—especially in those areas affected by the availability, use, quality, and influence of freshwater— is now recognized as a need to be addressed by multiple parties, and one that requires commitment and preventive action at all levels: local, national, regional, and global.
Freshwater runoff has a major impact on the health of important coastal and ocean ecosystems, ocean productivity, ocean circulation patterns, and hydrological balances, which are also influenced by natural fluctuation of the global climate system. The natural connectivity of rivers and oceans should be considered in coastal and watershed planning, especially in areas where this connectivity is highly sensitive and/or vulnerable (e.g., deltas/estuaries, low-lying coastal wetlands, small islands, glacier fjords, coral reefs).
Linking the management of freshwater and coastal/marine areas is an issue raised by several international organizations and conservation/environmental fora (e.g., UNEP-GPA, World Water Council, Global Water Partnership, Global Forum); in particular, they focus on the direct impacts from inland activities (e.g., agriculture, forestry, mining, urban development) on marine/coastal ecosystems, resources, and activities. However, other aspects of this linkage— such as human health and water safety issues, livelihood of coastal communities, and potential impacts from water-cycle changes and sea-level rise due to climate change impacts—have not been directly addressed within the context of land-based impacts on the marine environment.