NOAA announces easing of "worst global coral bleaching" event

The U.S. National Oceanic and Atmospheric Administration (NOAA) has announced that the worst bleaching of coral reefs worldwide in decades, a cycle that began in 2015, was finally easing.

NOAA said its latest forecast “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.”

Described by NOAA’s Coral Reef Watch Coordinator C. Mark Eakin as “the most widespread, longest and perhaps the most damaging on record,” the coral bleaching event is attributed to hotter sea temperatures brought on by the 2015-2016 El Nino, according to the AP story.

Healthy coral reefs are vital to the sustenance and protection of important species of fish, whereas bleached corals are susceptible to disease or death. Corals undergo bleaching when heat-induced stress causes them to expel the symbiotic photosynthetic algae on which they feed and which give them their color.

Meanwhile, Trinidad and Tobago’s State of the Marine Environment (SOME) report released in May differs somewhat on the impact of the 2015-2017 bleaching event on that country’s reefs.

The SOME report, produced by scientists at that country’s Institute of Marine Affairs, states that the 2010 bleaching event was, in fact, the worst one for Tobago’s reefs of the three global bleaching events recorded by NOAA – in 1998, 2010, and 2015 to 2017.

Further, the SOME report indicates that not all corals are created equal.

The islands’ marine scientists observe in the report that “the most notable trend” in Tobago’s coral reef communities was “a decline in hard coral cover.” Hard coral is giving way in many areas around Tobago to soft coral, sponges, and algae, causing concern since “hard corals are the reef builders – their polyps secrete the calcium carbonate that is responsible for the cementing and expanding coral reef structures over time. Percentage [of] hard coral cover is used globally as an indicator of reef health,” the SOME report states.

The report further notes that for Tobago’s reefs, other factors, along with warmer sea temperatures, have contributed significantly to the decline in the island’s hard coral cover over the past few decades. These factors include increased artisanal fishing, tourism, and unregulated coastal development.

NOAA has forecast that there remains some risk of bleaching of Caribbean coral reefs later this summer. NOAA uses ocean temperature data from geostationary and polar-orbiting satellites that it and its international partners operate to identify areas at risk of coral bleaching.


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