Why do corals bleach?
Corals bleach for a number of different reasons and scientists are actively studying coral bleaching to better understand what causes it. However, one of the main causes of coral bleaching is the presence of unusually warm seawater. Since corals are very sensitive to changes in temperature, warming of only 1 degree Celsius can cause corals to bleach. Since the oceans are warming as climate continues to change, the amount of bleached corals is expected to become more pronounced. Plus, the part of the ocean that warms the most is the sea surface and most reef corals live quite near the sea surface. There are other reasons that corals bleach too. Corals may bleach if salinity changes, if there are high levels of solar radiation (typically during summertime), if the reef is in the path of a large storm, if there is pollution in the water, or if sediment runoff from land makes its way to the reef. While bleaching is a natural reaction, it has become more common as human impacts on the ocean
