75% of Earth’s Coral Reefs Threatened

Three quarters of the world’s coral reefs are threatened by agricultural runoff, shipping, overfishing, coastal development, pollution, climate change, warming seas and ocean acidification according to a new report from the World Resources Institute, titled “Reefs at Risk.” The report is a follow-up to a 1998 report they did on the same global problem, but this time more detailed.

The document summarizes the global situation for coral reefs: “Warming seas have already caused widespread damage to reefs, with high temperatures driving a stress response called coral bleaching, where corals lose their colorful symbiotic algae, exposing their white skeletons. This is projected to intensify in coming decades. Ocean acidification reduces coral growth rates and, if unchecked, could reduce their ability to maintain their physical structure.” (Source: Reefs at Risk, Executive Summary) Conservation International calls the report the most detailed assessment of coral reef threats ever undertaken.

Coral Reef Locations

Why are coral reefs important? They provide the highest biodiversity for all marine ecosystems in the oceans. They also host 25 percent or more of all marine fish species. One estimate put the benefits coral reefs provide at 29 billion US dollars per year. They generate billions of dollars per year for tourism and recreation and are the foundation of life for many marine organisms.

Reefs around the world have been dying off due to the various impacts caused by human activity. When they are gone, the biodiversity depending on them also goes. As one researcher said, It’s like when everything in the forest is gone except for little twigs.”(Source: MSNBC.com)

Coral is an animal, not a plant. Reefs are generated when colonies of live corals grow together, then die, and become a hardened structure for new live corals to grow upon and the process is repeated. Coral polyps release eggs and sperm into surrounding water. When an egg meets a sperm a they become a larva. This baby coral floats until it finds a hard surface to attach to like a coral reef. Once it attaches, it begins building a shell made from carbon dioxide and calcium. The shell is made of calcium carbonate, aka limestone. It is hard and protects the coral inside.

These coral polyps are typically nocturnal, and release their tentacles at night to sting food (phytoplankton) and draw it inside to eat. They also can use photosynthesis for energy, if they contain an algae in their tissues, and most reef-building ones do. A coral reef can be made up of millions of individual coral polyps fused together. The most colorful parts of a reef are usually the live corals.

Some reefs are miles long like the Great Barrier Reef, which is over 1,000 miles in length. The basic configuration of the reef may have started developing 8,000 years ago. Portions of it have already died. About one third of reef-building corals are facing extinction.

Image Credit 1:Toby Hudson ; Image Credit 2: NASA; Image Credit 3: Public Domain

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