Back-to-back heatwaves kill more than two-thirds of coral

phys.org | 6/18/2019 | Staff
Matty123 (Posted by) Level 3
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By comparing reefs before and after two extreme heatwaves only 12 months apart, a collaborative team of researchers including scientists from Bangor's School of Ocean Sciences found that living hard corals in the central Indian Ocean reduced by 70 percent. Despite this, their results suggest that some coral species are more resilient to rising temperatures, which offers hope for these vital habitats.

For nearly eight weeks in 2015, seawater temperatures surrounding reefs in the British Indian Ocean Territory (BIOT) were unusually high. The team compared surveys of coral reefs before and afterwards to map changes that this increased water temperature caused to the archipelago's coral reefs.

Analysis - Today - Coral - Reefs - Heatwave

Their analysis, published today in the journal Coral Reefs, shows that the 2015 heatwave killed 60 percent of BIOT's hard corals at depths of up to 10 metres, with some species more affected than others. 86 percent of Acropora corals, for example, previously the most abundant, perished.

Before corals were given a chance to recover another heatwave struck BIOT just one year later, lasting for over four months. Although researchers were unable to assess its impact across all the islands, data they collected from the Peros Banhos Atoll showed that 68 percent of the remaining hard corals were bleached and 29 percent died, suggesting that approximately 70 percent of hard corals were lost between 2015 and 2017 overall.

Heatwave - Corals - Researchers - Corals - Temperatures

Interestingly, although the second heatwave lasted longer, fewer of the surviving corals were killed. Researchers believe that the remaining corals are more resilient to rising temperatures and that their ability to endure and regenerate may be key to protecting reefs from climate change-induced rises in sea temperatures.

Dr. Catherine Head of the Zoological Society of London said:

Data - Event

"Our data shows the event in 2016 was worse than in 2015, but it did...
(Excerpt) Read more at: phys.org
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