River pollution threatens health of protected coral reef

Research published in Science Advances finds the Flower Garden Banks National Marine Sanctuary, off Texas and Louisiana, is showing declining health tied to nitrogen pollution from Mississippi River agricultural runoff. Scientists extracted coral cores spanning 1753 to 2023 and found nitrogen levels rose unnaturally starting around 1850, sharply accelerating after the 1960s with the spread of synthetic fertilizers.

The team estimates 60-80% of the nitrogen reaching the sanctuary originates from the Mississippi basin, and found the years of worst disease outbreaks (2016, 2022) and bleaching (2022, 2023) coincided with the largest nitrogen influxes combined with extreme heat. Researchers warn outbreaks may become more frequent if the nutrient loading continues unabated.

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