Fauna Journal Entry

Reefs Hurt By Carbon Dioxide Rise (February 25, 2008)

The huge rise in global carbon dioxide levels is taking a big toll on coral reefs around the world. The gas makes ocean water more acidic and puts stress on living coral. Scientists say the planet's reefs could be gone completely by the end of this century without a big cut in greenhouse gas emissions.

When carbon dioxide dissolves in ocean water, it forms carbonic acid. This acid dissolves calcium carbonate in the skeletons of the coral, tiny animals known as cnidarians. Studies suggest coral can adapt to warmer temperatures, at least to a point. But coral can't tolerate higher acidity levels.

The world's coral reefs face many other dangers, including farm and city runoff, pollution, and overfishing. Another huge problem is coral bleaching, often a direct result of rising ocean temperatures. Warmer water can kill the algae that living coral depend on for food. When the algae dies, the coral turns white and often dies as well.

Coral reefs are called "rain forests of the sea" because of their rich biodiversity. They support one-third of the world's fish species and close to a million kinds of living things overall. Sadly, twenty percent of the world's reefs are already gone. An additional thirty percent are in serious trouble, according to the World Conservation Union.