Recycled restaurant shells rebuilt the Gulf seafloor over 17 years

The Coastal Conservation Association of Florida spent 17 years dumping over 500,000 tons of recycled oyster and clam shells back into the Gulf of Mexico, and the degraded seafloor rebuilt itself. The shells were gathered from seafood restaurants and processing plants, some scraped directly off plates. Critics called the plan reckless, and for a while even the researchers running it saw no visible change. Beneath the surface, the shells got to work. Bacteria formed a biofilm, the starting point for marine ecosystems and something scientists still struggle to recreate in a lab. As the shells disintegrated, they released calcium and gave baby oysters a hard surface to grow on, where before there had only been soft sand. The living oysters then filtered the water and held back algae blooms. Fish, turtle and dolphin numbers climbed to levels not seen in more than 25 years. Similar shell programs are now running in Alabama, Texas and the Carolinas.