Coral Bleaching in the BANP

April 1, 2020 | Zoe Whittall

Coral reefs cover just 0.1% of the world’s oceans, and yet they support nearly 25% of marine life. On a recent diving excursion off Benguerra Island, we noticed that some of the coral in the BANP is bleached.

This is interesting, as it coincides with the third mass bleaching of coral in Australia’s Great Barrier Reef in the last five years and what is thought to be the most widespread bleaching to occur there. 

Bleached coral in the Bazaruto Archipelago National Park.

The primary cause of coral bleaching is rising sea temperature, which stresses the coral. Coral have symbiotic algae, called zooxanthellae, which lives in their tissues and aids with photosynthesis. When stressed or over-heated, the coral ejects this algae, which causes them to turn white, or bleached. Coral does not necessarily die after bleaching, but they are more fragile and need time to recover. 

BCSS research manager Karen Bowles and activities manager Mauro Jije diving over the bleached coral.

Coral bleaching events are becoming more common in all the world’s oceans. According to the Carbon Brief website, “severe coral bleaching is five times more frequent than 40 years ago,” with the percentage of effected coral rising from 8%, as recorded in the 1980s, to 31% in 2016.  

A comparison of the sea temperature in 2018 and 2020 in the Bazaruto Archipelago National Park.

This large increase in coral bleaching is predominately caused by global warming, according to a study conducted by Royal Society research fellows and published in Science. The study was completed using data compiled between 1980 – 2016 on 100 reefs from 54 countries, and the increase in frequency is especially dangerous because coral needs over 6 years to recover from a bleaching event.

BCSS remote sensing work.

The increase in both frequency and severity of the bleaching is threatening coral reefs around the world, and we at BCSS work hard to do our part to spread awareness of this occurrence through observation.