Global Coral Bleaching (credit: NOAA & The Great Barrier Reef Foundation)

Coral bleaching occurs when coral becomes unhealthy and white due to environmental conditions that are not suited for algae (zooxanthellae) to remain in the tissues of coral. According to the National Oceanic and Atmospheric Administration (NOAA), coral and algae depend on each other to live. Algae leave coral when coral becomes stressed, causing the coral to become even more stressed and vulnerable to disease. When all the algae are gone, the corals become “bleached”. Coral bleaching is caused by warming temperatures of the ocean, pollution, overexposure to sunlight, low tides, and sometimes even water temperatures that are too cold.

When coral turns completely white, this does not mean it is dead. Corals get their color from the algae that live in their tissues. The Nature Conservancy states that algae provide food to the corals through the carbohydrates they produce during photosynthesis. After the algae are gone, there is no longer a food source for the  coral. This is when the corals change their color to white. Corals can survive after being “bleached” if algae are reabsorbed before they die.

The Great Barrier Reef Foundation stated that the worst bleaching event was in 2016 in the Great Barrier Reef in the Coral Sea, on Australia’s northeastern coast. It was triggered by record breaking ocean temperatures which reflect evidence of global warming caused by climate change. The Great Barrier Reef Marine Park Authority is now back in the water surveying the survivorship and recovery rates of coral after the recent bleaching event. Some are afraid that the Great Barrier Reef is damaged beyond full recovery. The Great Barrier Reef Marine Park Authority believe this event reinforces the need for an international effort to remediate climate change. Also, as a nation, Australia should try to reduce pressures on the Great Barrier Reef.

​Other reefs have been “bleached” due to temperature changes. NOAA found that the Caribbean lost half of its coral reefs from a bleaching event in 2005. This event was caused by the expansion of the warm waters southward from near the Virgin Islands and Puerto Rico. Cold water temperatures can also cause bleaching events. As any variation in temperature change is susceptible to bleaching. Cold water temperatures in the Florida Keys caused a coral bleaching event in January of 2010.

There are also negative effects coral bleaching events could have on humans. Nature International Journal of Science stated that Terry Hughes, who is a director of the coral-reef center at James Cook University in Australia, said: “if we fail to curb climate change, and global temperatures rise far above 2 degrees Celsius, we will lose the benefits they provide to hundreds of millions of people.” The Nature Conservancy said: “that although coral reefs make up less than 1% of the ocean’s ecosystems, they shelter 25% of marine species, protect shorelines, support fishing industries, provide tourist dollars, and could be home to the next big medical breakthrough.” The best thing we can do to prevent more coral bleaching is to live sustainably to reduce the high temperatures from climate change and to reduce ocean water pollution.

(Credit: NOAA, The Great Barrier Reef Foundation, The Nature Conservancy, Nature International Journal of Science)

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©2018 Weather Forecaster Brittany Connelly