Coral Bleaching Is Caused By Increasing Ocean Temperatures Says NOAA


The rising water temperatures in the Atlantic and Pacific oceans continue to cause the widespread bleaching of corals seen on reefs in the Northern Hemisphere, according to the National Oceanic and Atmospheric Administration (NOAA).

Experts believe this trend could potentially lead to mass deaths of corals and affect the supply of fish and shellfish in the long run.

Despite the ability of corals to recover from the effects of mild bleaching, long-term or severe bleaching can kill the marine invertebrates. Exposure to bleaching can also increase the susceptibility of corals to disease.

Once corals begin to die, it often takes years or decades for the reef system to recover. The reefs must also remain undisturbed in order for recovery to proceed.

Mark Eakin, coordinator of the NOAA's Coral Reef Watch, explained that the bleaching that began in June of last year has been devastating for the corals in the Pacific's western regions. He said the NOAA is concerned that the bleaching could spread to western Atlantic and back to Hawaii again.

According to the agency, after corals die off, the reefs start to degrade and the structures that the corals created begin to erode away. This reduces the level of protection for shorelines and lessens the number of natural habitat for both fish and shellfish.

At the beginning of 2015, members of the Coral Reef Watch conducted a four-month study of the situation titled Coral Bleaching Outlook. They provided an accurate forecast of the bleaching of corals in areas in the South Pacific, such as in Fiji, Nauru, Papua New Guinea, American Samoa and the Solomon Islands.

The study also predicted the coral bleaching in the Indian Ocean, such as in the Maldives and areas covered by the British Indian Ocean Territory.

The Coral Reef Watch's monitoring team fear that further coral bleaching in such a short period could result in a disaster for the corals that have yet to recover from last year's bleaching.

"Many healthy, resilient coral reefs can withstand bleaching as long as they have time to recover," Eakin pointed out.

"However, when you have repeated bleaching on a reef within a short period of time, it's very hard for the corals to recover and survive. This is even worse where corals are suffering from other environmental threats, like pollution or overfishing."

Coral bleaching happens when corals are subjected to drastic changes in the environment such as nutrients, light or temperature. Once it occurs, the corals are forced to release the symbiotic algae found in their tissue, causing the tissues to become pale or white.

Without these symbiotic algae, the corals lose their main food source and become more vulnerable to disease.

Experts said that widespread bleaching, such as the ones seen in the Pacific since 2014, can only be caused by high temperatures.

Photo: Oliver Dodd | Flickr

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