Coral reefs: we win some, we lose some

Andreas Wilson-Späth

There remains some truth to the old expression that humans know more about the surface of the moon than we do about the bottom of oceans.

Here’s a prime example: scientists have just discovered a huge coral reef system where nobody had expected to find one – in the Atlantic Ocean off the mouth of the Amazon River.

The reason why even experts are completely “flabbergasted” by the news is that corals don’t tend to do particularly well in the turbulent and muddy waters that characterise areas where large, sediment-laden rivers enter the sea. Yet, there it is, a 950km long reef system that covers approximately 9500 square kilometres at water depths of between 30m and 120m.

While shallow tropical reefs frequently challenge lush rainforests when it comes to biodiversity, the unusual location of this new reef means that it is less diversified. It is, however, still home to a wide variety of species of fish, sponges and other marine life forms.

That’s the good news. Sadly, the newly discovered ecosystem is already under threat from oil exploration, drilling and production in the region. According to the researchers who revealed it to the world, “such large-scale industrial activities present a major environmental challenge”.

Makes you wonder what else lies unseen beneath the waves of the planet’s oceans and how much of it we’re inadvertently trashing.

Elsewhere, other coral reefs are in bad shape. A recent, detailed aerial survey of the grandest of the all, Australia’s Great Barrier Reef, has shown that over 90% of the smaller reefs that make up this gigantic living complex have been devastated by something called ‘coral bleaching’.

This happens when corals are exposed to abnormally high water temperatures for periods of several weeks at a time. As the temperature rises, the tiny, colourful creatures (called zooxanthellae) which inhabit the hard coral structures abandon them, leaving them looking white and bleached.

If conditions return to normal, the organisms can recover slowly from the effects of coral bleaching, but if they persist for too long, the corals perish en masse.

Currently, the world’s oceans are experiencing a global coral bleaching event as the warming effects of El Niño and climate change combine. It’s one of only three such occurrences on record, all of them having been observed since 1998 and this one being the most severe yet.

According to Professor Terry Hughes, who heads Australia’s National Coral Bleaching Taskforce, the cause of the disaster is clear: “global warming – the link is incontrovertible”.

“We’ve never seen anything like this scale of bleaching before,” he says. “In the northern Great Barrier Reef, it’s like 10 cyclones have come ashore all at once”.

When the Australian Marine Conservation Society’s Imogen Zethoven, visited the scene during a recent dive, she was shocked: “I had expected some patches of bleaching surrounded by mainly healthy, colourful corals. I saw the opposite.”

She explains that “for decades, scientists and conservationists have been warning that climate change is an existential threat to the Great Barrier Reef and all the world’s corals. We know what needs to be done: a rapid transition to 100% renewable energy; an end to fossil fuel subsidies; the phasing out of coal-fired power stations; and keeping coal in the ground.”

I’ve never visited the Great Barrier Reef myself, but, as for many people, it’s high on my bucket list of places to experience before I die. I just hope it’s still alive when I finally manage to get there.

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