Lonely Planet Writer

Enormous coral reef discovered under the muddy waters of the Amazon

An enormous 3600 square mile coral reef has astonished scientists and the world alike after it was discovered under the muddy waters off the mouth of the Amazon.

The mirky waters of the Amazon hiding their coral treasure
The mirky waters of the Amazon hiding their coral treasure Image by Lance WIllis

The discovery was a complete surprise to oceanographers who had previously supposed that coral reefs couldn’t exist in rivers, which normally produce gaps or gulfs in reef systems.

In an interview in The Atlantic co-author of the paper published in Science Advances which brought the news to a wider public, Patricia Yager described herself and her 29 colleagues as being “flabbergasted” by the discovery.

“Traditionally our understanding of reefs has focused on tropical shallow coral reefs which harbour biodiversity that rivals tropical forests.”

The reef is 600 miles long, stretching from French Guiana to Brazil’s Maranhao state with depths that range from 30 to 120 metres deep.

Scientists were flabbergasted by the discovery of the reef
Scientists were flabbergasted by the discovery of the reef Image by Lance Willis

There was little evidence before the discovery that coral reefs could flourish in muddy waters like those of the Amazon, which deposit a thick sediment on all that lies below. Corals normally thrive in salty, clear and sunlit waters.

But oceanographers discovered that the reef was benefiting from a fresh water “plume” that brings the water flow out towards the ocean. They also described the coral as relatively impoverished, meaning it is not as rich in biodiversity as its oceanic brothers.

In spite of that though the reef has yielded 73 species of fish, 60 species of sponges, stars and spiny lobsters.