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Why are coral reefs in peril and what is being done to protect them?

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Coral reefs are at risk from natural processes and human activities.

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Oil spills and pollutants can threaten entire reefs.

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Excessive nutrients from land, such as sewage and agricultural fertilizers, 

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promote the growth of algae that can smother corals.

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Coral productivity is also decreased when land development for agriculture, 

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industry, and housing increases sediment carried to coastal waters as runoff.

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Runoff clouds the water, blocking light needed for algae living in the corals.

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When stressed, corals "bleach," expelling the algae critical to their health.

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The USGS is helping to understand the biological and geologic controls...

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that affect our Nation's coral reefs by mapping, monitoring, and studying them.

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Visit USGS.gov for more information.