Coral Reefs & How Pollution Affects Them

Corals reefs in Australia's Great Barrier Reef are sensitive to pollution.

Pollution is one way coral reefs are slowly being destroyed. Industrial toxins such as oil, mercury, sewage and acid rain enters the coral through the polyps, the builders of coral. When the polyps are killed, new coral cannot be formed and soon after, the entire coral dies and rots away. The most common source of pollution that directly affects coral come from oil spills, jetskis, exhaust pollution from ships, and dumping of hazardous waste.

Land-Based Pollutants

Land-based pollution is the primary cause of coral reef destruction throughout the world. In the Caribbean, for example, about 80 percent of ocean pollution originates from activities on land. Human expansion in coastal areas have increased quantities of runoff, which carries pollutants and sewage into the environment and threatens the well-being of the coral. Results from runoff include decreased oxygen levels in the water and excess fertilizer, which leads to algae blooms. These algae blooms smother coral seeds, which are necessary for reproduction.

Pesticides and Coral

Pesticides such as DDT and organo-chlorine pesticides, according to a 2006 study by the Marine Ecology Process Series in Australia's Great Barrier Reef, kill and destroy large amounts of coral. These pesticides in even small amounts can have devastating effects on coral. Aside from destroying existing coral, new coral spawning is rendered ineffective by these pesticides, which kill off newly spawned coral.

Marine Debris Pollution

Marine debris is any human-made object that is dumped into coastal or ocean water. Debris can enter the ecosystem from ships, runoff from rivers, streams and storm drains. Examples include glass, fishing nets, rubber tires, fishing line, and even entire vessels. Marine debris affects coral in several ways. Fishing nets often entangle and kill reef organisms and break apart coral. Tires, lines, and vessels limit the area in which new coral can spawn.

Radioactive Waste

Between 1946 and 1970, at least 89,472 drums of radioactive waste were unaccounted for after being lost at sea. This waste does not dissipate into the ocean. Instead, it will retain its radioactivity and lethal qualities for the next several thousand years, polluting large quantities of ocean. Coral, which are sensitive to pollution and even slight environmental changes, have a low tolerance for radioactive waste.

Sedimentation and Coral

The accumulation of sedimentation from human activities, such as construction, are a major source of coral destruction. As coastal cities become more populated, construction increases and sedimentation increases also. Erosion of beaches also adds sedimentation, which smothers corals and destroys the reef.

References

• NOAA.gov: How Pollution Affects Coral Reefs
• South China Sea.org: Coral Reef Pollution in the South China Sea