Wildlife

Scientists discover coral reef near the mouth of the Amazon River

Scientists have discovered a vibrant coral reef ecosystem near the mouth of the Amazon River that stretches roughly 3,700 square miles -- even though coral isn't supposed to be able to grow there in the first place.

The reef described in the journal Science Advances could shed light on how these delicate organisms, which provide essential scaffolding for so much marine wildlife, might survive in less-than-ideal conditions.

Coral are tiny little soft-bodied animals, related to anemones and to jellyfish, that band together to build their protective, rock-like reefs by pulling calcium and carbonate out of the ocean water. Reefs serve as hot spots of biodiversity, home to a vast array of sea creatures, from crabs, sea urchins and algae to fish, sharks and turtles.

Coral reefs thrive in clear waters along tropical shelves, but river systems like the Amazon are thought to create gaps where they do not grow. That’s in part because the plume of murky, sediment-filled water spilling out from the gargantuan river and into the ocean doesn’t allow much light to come through.

So the discovery came as a total surprise to study coauthor Patricia Yager, an oceanographer at the University of Georgia, who in 2012 set out with Brazilian scientists aboard the research vessel Atlantis to study the plume coming out from the river mouth and flowing into the ocean.

There’s a certain amount of irony in the discovery, as the system is already under threat from oil drilling and high levels of fishing in the area, the scientists said.