Why Do We Need to Protect Coral Reefs?

Coral reefs are some of the oldest organisms on earth dating back millions of years.

Mass coral bleaching events and marked degradation of coral reefs worldwide have lead to calls to action from the scientific community encouraging coral reef conservation. Protecting coral reefs is important because reef ecosystems provide a valuable source of food, contribute to the world economy, provide coastal flood and erosion control, and contain an untapped source of medicinal compounds. Protecting coral reefs has become necessary due to the numerous pressures facing reefs.

Water Pollution

Trash and other pollutants threaten the survival of reef inhabitants including sea urchins.

According to the Coral Reef Alliance, "scientists have identified pollution as one of the leading causes of coral reef degradation." Sources of water pollution are widespread from fertilizer runoff and raw sewage, to oil spills and large and small pieces of trash. According to the Air and Waste Management Association (AWMA), an oil spill contaminates every tier of the marine food chain and can severely damage the fisheries that provide food and livelihoods to coastal communities. Large trash items, such as discarded nets and plastic bottles, can ensnare marine organisms and smaller bits of disintegrated plastic can poison organisms that mistake it for food. Both the Pacific and Atlantic oceans have massive garbage patches stretching for miles in the open ocean. Some of the garbage escapes the patches to end up as food for corals and other reef inhabitants.

Coastal Development

Deforestation causes sedimentation in coastal reef waters.

The problems associated with coastal development are twofold: as coastal populations increase, so do pressures on nearby reefs as a source of food. Likewise, as populations increase, so do construction and other economic activities such as mining, farming and logging, all of which exacerbate sedimentation. Sedimentation occurs when coastal land erodes and makes its way into the ocean. Deforestation and other activities that disturb the soil magnify problems with erosion. Heavy water sedimentation blocks sunlight and can destroy the corals in an affected area.

Overfishing

Overfishing large species such as tuna threatens the entire reef ecosystem.

Overfishing is destructive to reefs because it shifts the balance of reef ecosystems. In the Caribbean, for example, many herbivorous fish species have been fished to the point of regional extinction. With limited remaining algae grazers, the coral reefs of the Caribbean suffer from strangling algae overgrowths. Outbreaks of coral-eating, crown-of-thorns starfish in the Great Barrier Reef are also linked to overfishing. Natural predators of the starfish include giant triton snails, humphead maori wrasses, starry pufferfishes and titan triggerfishes, all of which are under fishing pressure due to demand from the live aquarium trade.

Ocean Acidification

Ocean acidification causes coral skeletons to become fragile making survival difficult.

"Ocean acidification" refers changes in the ocean's chemistry due to rising levels of carbon dioxide in the atmosphere. The ocean absorbs carbon dioxide, which affects seawater chemistry. According to the National Oceanic and Atmospheric Administration (NOAA), acidification lowers the ocean's pH and reduces the amount of calcium available to shellfish and corals. Calcium is the foundation of protective shells and skeletons, and reduced calcium absorption renders corals and shellfish less able to withstand the ocean's turbulent waves. Increased amounts of carbon dioxide in seawater are also believed to cause increases in algae overgrowth in struggling coral reefs.

Debate

Fossil records show that coral reefs have endured cycles of extinction and re-growth.

Fossil records show that coral reefs have endured many cycles of extinction followed by periods of re-growth, and the most recent evidence indicates we are in the midst of another coral die-off period. Skeptics of coral reef conservation cite past coral extinctions as evidence that coral reef die-off is natural and coral reefs do not need protection. However, studies indicate that stressors are causing species to disappear at an unprecedented rate that is exponentially greater than any past extinction. Coral reef formation takes millions of years and if coral reefs continue to die at the current rate, the world will lose valuable resources that will take millions of years to regenerate.

References

• Air and Waste Management Association (AWMA); Oil Spills
• Coral Reef Alliance; Threats to Coral Reefs
• The Cooperative Research Centre for the Great Barrier Reef World Heritage Area
• National Geographic; Huge Garbage Patch Found in Atlantic Too
• NOAA's Pacific Marine Environmental Laboratory (PMEL) Carbon Dioxide Program