Pollution

  • Pollution from human activities on land contributes to coral reef damage when transported by rivers into coastal waters.
  • Impacts from land-based sources of pollution from agriculture, coastal development, deforestation, storm water, road construction, and oil and chemical spills on coral reef ecosystems include increased sedimentation, nutrients and toxins.
  • Sediment, pesticides, and toxins can damage coral reefs when transported by rivers into coastal waters. These result in the smothering of corals, reduced light levels and over-nutrification of reef communities.
  • These pollutants can cause disease and mortality in sensitive species, disrupt critical ecological functions, cause structural reef changes and impede growth, reproduction, and larval settlement.
  • Trash also kills coral reef systems and the species that rely upon them for survival. Floating trash can cover reefs, blocking off critical sunlight.
  • Feeding turtles often mistake plastic bags for jellyfish--plastic pollution blocks the turtle's digestive tract, causing them to starve to death.
  • Pollution is a particularly serious threat to reef systems near the mouths of watersheds, as the high level of freshwater flow and sediments carried by major rivers inhibits coral growth.
  • In the Pacific between Hawaii and Indonesia, reefs have been losing about 1 percent of their coral annually over the last 25 years.
  • Land clearing also impacts the health of coral reeds as watersheds cleared of their forests and other vegetation are extremely vulnerable to erosion and flooding.
  • In addition to sediment, land-based sources of pollution to coral reef ecosystems include pesticides, petroleum hydrocarbons, pharmaceuticals, heavy metals, pathogens, and excess nutrients.