December 17, 2017

Coral Reefs at Risk from Extreme Heat



Great Barrier ReefScientists fear widespread die-offs in the ocean endangering the richest ecosystems and fisheries that feed millions of people because of severe stress put on the coral reefs in the extreme heat. Corals are reacting to the heat by bleaching and going into survival mode. Many reefs from Thailand to Texas  have already died and more are expected to do so. Corals in the Caribbean may undergo drastic bleaching due to changes in water temperature.

1998 was the hottest year in historical record when 16 percent of the world's shallow water reefs died. This year the situation is looking worse. Scientists have warned that corals which are highly sensitive to excess heat, would be an early indicator of the ecological distress on the planet caused by buildup of greenhouse gases and linked to climate change.

High ocean temperatures in 2010 have been hottest January to August and matched to 1998. 2010 is also an El Nino year. Coral reefs, the rainforests of the sea, are made up of millions of tiny animals called polyps that supply the algae with nutrients and a place to live. 

High heat and bright sunshine cause the metabolism of the algae to speed out of control and they start creating toxins. Corals then become vulnerable, starve to death and may never recover. Serious bleaching has been seen recently in the flower Garden Banks off the Texas-Louisiana border. Caribbean reefs are at risk but tropical storms moving through the Atlantic have cooled the water there and saved some corals.

If Australia has a poor monsoon season this summer, the Great Barrier Reef is in for serious bleaching.