For years, oceans have been used as dumping grounds for many types of waste, including sewage, industrial waste, chemicals and litter. More than 80 percent of marine pollution originates from land-based wastewater and sediment and nutrients delivered via waterways. In South-East Asia alone, 600,000 tonnes of nitrogen are discharged from major rivers into the ocean each year, and it is expected that by 2030, these nitrogen inputs will increase globally by at least 14 percent. More recently, policy changes in many countries have reflected the opinion that oceans do not have an infinite capacity to absorb society’s waste. However, marine pollution remains a major problem that threatens marine life, and consequently, the provision of marine ecosystem services.
Sources of land- and marine-based pollution in coastal ecosystems are wide‑ranging. The focus of this science-to-policy brief is on wastewater pollution impacting coral reefs, including from point sources (single identifiable sources) that discharge directly into coral reef environments, and indirect or diffuse sources such as urban, rural and industrial activities on land that discharge into the ocean via waterways. Accidental pollution, such as oil or chemical spills, is not considered here.
