Coral reefs face a number of global and local stressors. Over the last decade, the percent of threatened reefs has increased by 30%, and global and local stressors currently threaten nearly 75% of the world’s reefs.ref Over the last three decades, bleaching has been reported from virtually every region that supports coral reefs, and no region of the world’s tropical and subtropical seas appears safe from bleaching. ref

This section presents information on the major stressors affecting coral reefs as well as on the ecological response of corals to these stressors.

An anchor from a large ship damaged this coral reef in the western Pacific. Photo © Wolcott Henry 2005/Marine Photobank

Last updated January 26, 2018

Climate and Ocean Change

Climate change is impacting our oceans through the increase of sea surface temperatures, sea-level rise, changes in storm patterns, changes in precipitation, and altered ocean currents. In addition to human-driven climate change, natural changes in the ocean also occur. Learn more.


Coral bleaching is a stress response which can be caused by a number of factors such as elevated water temperatures combined with sunlight. Learn more.

Ocean Acidification

Increasing atmospheric CO2 is absorbed by the ocean and leads to changes in the ocean's carbon chemistry. Learn more.

Local Stressors

Anthropogenic stressors, including overfishing, destructive fishing, pollution, coastal development, tourism, and recreational impacts, threaten over 60% of the world's coral reefs. Learn more.

Coral Disease

Coral diseases have increased in frequency, intensity, and geographic range over the last several decades. Combined with hurricane damage, coral bleaching, and other natural stressors, these diseases are responsible for widespread coral mortality. Learn more.

Invasive Species

Eighty-four percent of the world's marine ecosystems are already affected by invasive species including invasive algae, invertebrates, and fish. Learn more.

Predator Outbreaks

Coral predators, including crown-of-thorns starfish, urchins, and Drupella (marine snails), cause tissue loss in corals, because they feed on live coral tissue. Learn more.

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