Aquatic Pollution and Coastal Management

Unit 13 : Coastal zone and anthropogenic activities

13.7.Waste Disposal, Pollution and Oil Spills
Pollution is generally considered to include solid and liquid waste, garbage, sewage, industrial and domestic runoff, sediment, chemicals including fertilizer, pesticides and oil. The coastal zone is the ultimate depository of most pollutant, whether they originate from land or from the sea. Of the land-based sources of pollution, eutrophication from human sewage disposal is a growing problem particularly in the vicinity of large coastal cities and harbours. Increased nutrient loading from sewage stimulates algal growth and degrades coral reefs and sea grasses. Fisheries production may also decline and bacteria in the sewage may pose a threat to human health. Other effects include loss of recreational swimming areas and damage to drinking water supplies. Activities outside of the coastal zone may also have a direct impact on the health of the coastal areas, for example when sedimentation and pollution from forestry and agriculture enter coastal areas via rivers and other waterways. Agricultural pesticides and fertilizers result in changes in the reef and sea grass communities and may in high concentrations cause fish kills in areas of poor water circulation. Sedimentation from land clearance results in increased water turbidity, which in turn decreases the productivity of coral reefs and sea grasses. With high levels of sedimentation, physical smothering of corals, the benthic organisms by sediments and fine silt may take place.