Protecting the Oceans from Land-based Activities: Land-based Sources and Activities Affecting the Quality and Uses of the Marine, Coastal and Associated Freshwater Environment - GESAMP Reports and Studies No. 71

This report examines the degradation of marine and coastal environments caused by activities originating on land and evaluates their effects on the quality and use of marine, coastal and associated freshwater systems. Environmental processes are complex and involve interactions within the biosphere and the abiotic environment, meaning environmental problems are interconnected and extend beyond political boundaries. Marine environmental issues therefore cannot be addressed without recognising the ecological interdependence between oceans, coastal zones and associated freshwater systems. The report explains that environmental and ecological systems are strongly influenced by social and economic conditions, while also shaping them. A large proportion of the world’s population lives in coastal areas and depends on marine resources, maritime employment and coastal recreational opportunities. However, increasing population pressure, changing consumption patterns and growing demands for space and natural resources place considerable stress on these environments. These pressures, combined with weak economic performance and widespread poverty in many regions, undermine the sustainable use of oceans and coastal areas. Within this context, the report reviews major environmental problems affecting marine and coastal environments, including habitat destruction, sewage-related risks to human health, eutrophication, declining fish stocks and changes in sediment flows caused by hydrological alterations. It also analyses how pollutants from domestic sewage, industrial discharge, agricultural runoff, mining activities and solid waste enter marine ecosystems and contribute to environmental degradation and public health risks.