How Pollution From Land Reaches and Harms Coral Reefs

Some of the worst damage to coral reefs starts on land. Toxicants, sediments and nutrients washed off the land are now well accepted as among the most serious stresses on coral reef ecosystems. They slow coral growth and reproduction, disrupt the way the ecosystem functions, and cause disease and death in sensitive species.

Where the pollution comes from

As populations grow and development spreads along the coast, the landscape changes and more pollution washes toward the reefs. Each source brings its own mix:

What it does to a reef

Pollution — sediment, toxins, pathogens and extra nutrients — causes disease and death, disrupts the ecosystem's functions, changes its dynamics and feeding behavior, and prevents corals from growing and reproducing.

Islands have it hardest

In the U.S., many coral reefs are heavily affected by altered watersheds, runoff and coastal development. On U.S. islands in the Pacific and the Caribbean, agriculture, deforestation, grazing by feral animals, fires, road building and urban growth have changed drainage basins and increased the pollution reaching nearby reefs. The geography and climate of tropical islands make many of these problems worse, which creates management challenges found nowhere else.

How you can help

• Use fertilizers and pesticides sparingly.
• Pick up after your pets.
• Wash your car on your lawn, and put lawn clippings in a compost pile.
• Collect rainwater from your roof with rain barrels or rain gardens.
• Never dump paint, oil, antifreeze, debris or other household chemicals into gutters or storm drains, and clean up spilled brake fluid, oil, grease and antifreeze.
• Keep your septic system working, with inspections and pump-outs every 3-5 years.
• Seek shade between 10 am and 2 pm, wear sun-protective clothing (UPF), and choose sunscreens with chemicals that don't harm marine life.

Sources

Based on "How does land-based pollution threaten coral reefs?" from NOAA's National Ocean Service, a work of the United States government in the public domain.