Huge coral reef discovered at Amazon river mouth

Apr 23, 2016

By John Vidal

A huge 3,600 sq mile (9,300 sq km) coral reef system has been found below the muddy waters off the mouth of the river Amazon, astonishing scientists, governments and oil companies who have started to explore on top of it.

The existence of the 600-mile long reef, which ranges from about 30-120m deep and stretches from French Guiana to Brazil’s Maranhão state, was not suspected because many of the world’s great rivers produce major gaps in reef systems where no corals grow.

In addition, there was little previous evidence because corals mostly thrive in clear, sunlit, salt water, and the equatorial waters near the mouth of the Amazon are some of the muddiest in the world, with vast quantities of sediment washed thousands of miles down the river and swept hundreds of miles out to sea.

But the reef appears to be thriving below the freshwater “plume”, or outflow, of the Amazon. Compared to many other reefs, the scientists say in a paper in Science Advances on Friday, it is is relatively “impoverished”. Nevertheless, they found over 60 species of sponges, 73 species of fish, spiny lobsters, stars and much other reef life.


Continue reading by clicking the name of the source below.

One comment on “Huge coral reef discovered at Amazon river mouth”

  • @OP – But the reef appears to be thriving below the freshwater “plume”, or outflow, of the Amazon. Compared to many other reefs, the scientists say in a paper in Science Advances on Friday, it is is relatively “impoverished”. Nevertheless, they found over 60 species of sponges, 73 species of fish, spiny lobsters, stars and much other reef life.

    This would suggest a strongly stratified water column above the delta with clear cooler salt water below the muddied freshwater from the river. If the reef is well off-shore, then only fine silt will be remaining in the surface layer of fresh water, after heavier particles have previously dropped out in the delta behind it.
    It seems that in the equatorial sunlight, enough light penetrates below the muddied freshwater plume, to support the corals.

    If there is surface pollution from oil drilling in addition to the muddy surface water, that could tip the balance, damage wild-life, and trigger erosion of the sea-bed.



    Report abuse

Leave a Reply

View our comment policy.