Surge in Nitrogen Has Turned Sargassum into the World’s Largest Harmful Algal Bloom

Scientists have discovered dramatic changes in the chemistry and composition of Sargassum, floating brown seaweed, transforming this vibrant living organism into a toxic “dead zone.” Results suggest that increased nitrogen availability from natural and anthropogenic sources, including sewage, is supporting blooms of Sargassum and turning a critical nursery habitat into harmful algal blooms with catastrophic impacts on coastal ecosystems, economies, and human health. Globally, harmful algal blooms are related to increased nutrient pollution.