Coral-Covered Anchor - National Geographic

Coral-Covered Anchor

Photograph by Raul Touzon, National Geographic

An 18th-century sailing ship dropped this anchor on a West Indies coral reef. Today’s human impacts aren’t always as obvious—but they are far more serious.

Pollution and overfishing can harm reef ecosystems locally. Climate change is causing trouble for reefs around the world, like coral bleaching episodes and increasingly acidic waters. Some scientists fear that 30 percent of the world’s reefs could be gone in 30 years.