New Discovery: A Massive Reef System at the Mouth of the Amazon River

Could coral reefs have anything to do with the Amazon River? Apparently so. In case you missed this new finding among the sea of reports about the impending demise of coral reefs (especially the Great Barrier Reef) across the world, here’s the lowdown: A team of scientists from Brazil and the United States have discovered a 600-mile long sponge and coral reef at the mouth of the Amazon River, where it empties into the Atlantic Ocean.

The reef stretches across more than 3,600 square miles in ocean floor off of the South American continental shelf, between the French Guiana-Brazil border and the Maranhão State in Brazil, according to the researchers whose findings were published in the journal Science Advances on Friday.

Here’s why this is unexpected and amazing: First, coral reefs are usually found in clear, briny water, off the continental shelf in tropical areas — waters where sunlight can penetrate. Yet the water where the Amazon meets the Atlantic is anything but clear. In fact, the Amazon plume — the area where freshwater from the river mixes with the salty ocean — is full of sediment and pollutants and is among the muddiest plume areas in the world. Then there’s the fact that plume areas are places where there usually tend to be gaps in the reef distribution along the tropical shelves.

Yet the researchers who discovered this novel reef system say that while it is “impoverished in terms of biodiversity,” it is pretty extensive. The finding has marine scientists revising their idea of how and where reefs can exist. “We found a reef where the textbooks said there shouldn’t be one,” study co-author Fabiano Thompson of the Federal University of Rio de Janeiro told National Geographic.

Scientists have been hunting for this deepwater reef system since the 1970s after some researchers caught reef fish at the mouth of the Amazon. But until now, no one knew for sure if it existed. The study’s lead author, Rodrigo Moura of the Federal University of Rio de Janeiro,…

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