Surge in Nitrogen Has Turned Sargassum Into the World's Largest Algal Bloom

For centuries, pelagic Sargassum, a floating brown seaweed, has grown in low nutrient waters of the North Atlantic Ocean, supported by natural nutrient sources such as excretions from fish and invertebrates, upwelling, and nitrogen fixation. Using a unique historical baseline from the 1980s and comparing it to samples collected since 2010, researchers at Florida Atlantic University and collaborators have discovered dramatic changes in the chemistry and composition of Sargassum that have transformed this vibrant living organism into a toxic "dead zone."The findings of the U.S. National Science Foundation-funded research, published in Nature Communications, suggest that increased nitrogen availability from natural and human sources, such as sewage, is supporting