A new study published in Ocean & Coastal Management by the Wildlife Conservation Society (WCS) and the University of Queensland, Australia, has found that nearly three out of four of the world’s marine protected areas (MPAs) are polluted by sewage. In regions most critical for coral reefs and tropical marine life, the situation is worse: 87–92 percent of MPAs are affected, with pollution levels inside protected zones averaging ten times higher than in nearby unprotected waters.
Researchers evaluated more than 16,000 MPAs worldwide, mapping how nitrogen from wastewater reaches protected areas. Wastewater carries nutrients, pathogens, and chemicals that damage coral reefs and seagrass beds, fuel harmful algal blooms, and have been linked to Alzheimer’s‑like brain disease in dolphins. Human health impacts are severe as well, with polluted drinking water contributing to an estimated 1.4 million deaths annually and up to $12 billion in economic losses.
The findings raise concerns for the global “30 by 30” pledge to protect 30 percent of the ocean by 2030. “In region after region, the areas set aside for conservation were actually receiving more pollution than the areas with no protection at all,” said lead author David E. Carrasco Rivera.
WCS Global Water Pollution Lead Dr. Amelia Wenger warned that even well‑managed MPAs cannot succeed if pollution continues to flow in from land. The study urges governments to integrate wastewater management into ocean protection plans and to link area‑based conservation targets with broader goals on land‑use planning, restoration, and pollution reduction.
