Sometimes, scientists discover natural phenomena in places where they shouldn’t be – like the vibrant coral reef ecosystem that nobody expected to thrive near the mouth of the Amazon River.
Stretching for about 3,700 square miles, the reef described in the journal Science Advances could offer some insight on how these fragile organisms can survive and even prosper in less-than-ideal conditions.
Unlike what some people might think, corals are not plants or vegetation covering the seabed – they are little soft-bodied animals, cousins to jellyfish and anemones. Feeding on the calcium and carbonate in the ocean water, the coral links together to build protective, rock-like reefs.
Coral reefs are some of the hottest spots of biodiversity, serving as home to many sea creatures, such as algae, fish, crabs, sea urchins, sharks, and turtles.
Tropical, clear waters offer the best conditions for coral reefs to thrive because there’s enough light coming through. However, river systems like the Amazon are largely believed to be reef-free because of the murky, sediment-filled water flowing out from the giant river.
Therefore, study co-author Patricia Yager, an oceanographer at the University of Georgia, was really surprised to see corals at the mouth of the Amazon river.
The discovery was made during the research of the plume in the river mouth that flows into the ocean, which started in 2012 with a team of Brazilian scientists.
But during this time, researcher Rodrigo Moura of the Federal University of Rio de Janeiro was curious to further investigate a paper from the 1970s that suggested that reef fish had been found near the continental shelf.
Moura and another researcher started pinging the seafloor with the help of an acoustic detector, pointing out spots that might be coral. Later, Moura used a dredge to gather samples out of the water – and hit the jackpot.
During a research trip in 2014, the Brazilian team came back on location and collected even more samples, ultimately uncovering an abundance of corals, brittle stars and reef fish in the most unwelcoming conditions.
According to Yager, these reefs might act as stepping stones between the Brazil reefs and the Caribbean reefs, offering the animals that live here a temporary refuge.
They might also hold some valuable information on how coral reefs will survive in the future, in less than optimal conditions as the oceans become increasingly unfriendly and suffocating them.