Life’s a bleach: climate change threatens the future of corals

The world’s corals are in a precarious state. These animals—which support the largest concentrations of global marine biodiversity and provide ecosystem services to over half a billion people—are in the midst of one of the worst global mass bleaching events in history.

(c) David Obura

(c) David Obura

Bleaching occurs in response to increased water temperatures which cause coral to expel zooxanthellae, the photosynthetic algae that provide the dramatic colours seen across healthy reefs. The loss of zooxanthellae causes the coral to turn white, or ‘bleach’. The algae can return if temperatures drop, and the bleached corals can recover. However, prolonged exposure to the high temperatures can cause the coral to die.

The ongoing El Niño phenomenon–which has led to the two warmest months globally on record–in conjunction with climate change, is causing damage to reefs across the planet, from the Florida Keys to the Great Barrier Reef.

©Pash Baker - Kirsty & soft corals

EDGE Corals Coordinator Kirsty Richards surveys corals

The current bleaching event is considered the worst to ever affect the Great Barrier Reef, with damage so tremendous that only 7%, or 68 of the 911 surveyed reefs, show no signs of damage. Almost a quarter of the coral of the Great Barrier Reef has been killed during the latest mass bleaching, and the length of the catastrophe is so extreme that a large proportion of damaged corals are not expected to recover.

It is currently unclear what impact this ecological catastrophe will have on the global diversity of corals, and the EDGE of Existence team are hoping to identify which EDGE coral species are most likely to be affected by bleaching.

EDGE corals represent the most evolutionarily distinct corals that are threatened with extinction. These species comprise millions of years of unique evolutionary history, such as the coral Poritipora paliformis, which diverged from its closest relatives over 50 million years ago.

The loss of such unique species would dramatically reduce the biodiversity of global marine environments. EDGE Fellows are working around the world, from the Caribbean to the Maldives, to improve the future for these incredibly important animals.

 

 

 

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