Environmental issues with coral reefs

Human impact on coral reefs is significant. Coral reefs are dying around the world. In particular, coral mining, pollution (organic and non-organic), overfishing, blast fishing and the digging of canals and access into islands and bays are serious threats to these ecosystems. Coral reefs also face high dangers such as diseases, destructive fishing practices and warming oceans. In order to find answers for these problems, researchers study the various factors that impact reefs. The list of factors is long, including the ocean's role as a carbon dioxide sink, atmospheric changes, ultraviolet light, ocean acidification, viruses, impacts of dust storms carrying agents to far-flung reefs, pollutants, algal blooms and others. Reefs are threatened well beyond coastal areas.

In 2008 estimates assembled from coral reef specialists from around the world indicated that 19% of the existing area of coral reefs has already been lost, and that a further 17% is likely to be lost over the subsequent 10–20 years. Only 46% of the world’s reefs could be currently regarded as in good health. About 60% of the world's reefs may be at risk due to destructive, human-related activities. The threat to the health of reefs is particularly strong in Southeast Asia, where 80% of reefs are endangered. By the 2030s, 90% of reefs are expected to be at risk from both human activities and climate change; by 2050, all coral reefs will be in danger.

In the Caribbean Sea and tropical Pacific ocean, direct contact between coral and 40–70% of common seaweeds cause bleaching and death of coral tissue via allelopathic competition. The lipid-soluble extracts of seaweeds that harmed coral tissues also produced rapid bleaching. At these sites bleaching and mortality was limited to areas of direct contact with seaweed or their extracts. The seaweed then expanded to occupy the dead coral's habitat. However, as of 2009, only 4% of coral reefs worldwide had more than 50% algal coverage. Further, there is no recent global trend towards algal dominance.

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