Coral Reefs are underwater ridges created by a colonial organism called coral as it builds its own protective housing. They provide shelter, breeding grounds, and nursery habitat for many ocean inhabitants including ecologically and economically important species. They have one of the highest levels of biodiversity on the planet and protect shores from storms.
Coral reefs are fragile and sensitive to changes in water temperature and water quality. In recent years, rising ocean temperatures have caused coral bleaching. This occurs when corals expel their zooxanthellae due to environmental stress, such as high temperatures or pollutants. When zooxanthellae, who give coral their bright colors, are expelled, corals appear white and die. Dead corals will erode, depleting the rich, highly diverse ecosystems they support.
Ocean acidification stems from the sea’s absorption of human-generated carbon emissions. The ocean absorbs 30 percent of the carbon dioxide put into the air through fossil fuel burning. This triggers a chemical reaction that produces hydrogen, thereby lowering the water’s pH.
In 2015, NOAA declared the beginning of the third ever global coral bleaching event. The first event was in 1998 and the second one in 2010. Since then above normal temperatures (that can cause bleaching) have effected more than 70 percent of all tropical coral reefs around the world. Hit hardest were the U.S. coral reefs, with two years of severe bleaching in Florida and Hawaii.
After analyzing new information from satellite and model data, NOAA’s forecasting shows that widespread coral bleaching is no longer occurring in all three ocean basins, Atlantic, Pacific and Indian, indicating the likely end to the global coral bleaching event. The high ocean temperatures lingered for three years, the longest period since the 1980’s.
Even as it appears that the third coral bleaching event is over some U.S. coral reefs are still not completely in the clear. The four month coral bleaching outlook shows some risk to coral reefs in Hawaii, Florida and the Caribbean later this summer.
In a NOAA press release, Jennifer Koss, director of the NOAA Coral Reef Conservation Program said, “coral reefs are not beyond help. Many proactive steps to make coral reef ecosystems more resilient are being taken around the world. We are reducing local threats to coral, and are looking into innovative ways to increase coral populations and species that are more resilient to rising ocean temperatures and acidified waters.”
