Researchers have identified a vibrant and extensive 1,000km-long coral reef in the waters of the Amazon river mouth during an expedition.
Corals are known to usually thrive in clear, salty water so the fact that they were present in very muddy waters came as a surprise.
University of Georgia oceanographer Patricia Yager told National Geographic, “We brought up the most amazing animals I’ve ever seen on an expedition like this.”
The team recorded a total of 73 fish species, 61 sponge species and 35 algae species.
However, these numbers are not high in comparison with other existing reefs and experts described the reef as ‘impoverished’ in terms of biodiversity.
The paper reveals that the reef is facing the threat of development. It states, “A total of 80 exploratory blocks have been acquired for oil drilling in the study region, 20 of which are already producing.”
The abundance of sponges in the Amazonian reef provides some support for the theory that a coral-dominated reef can shift to a sponge-dominated reef due to increases in local stressors.
Researchers are planning to carry out further research.
Co-author of the Science Advances report Fabiano Thompson says, “We’ve mapped only 10% of the area. Other expeditions are required in order to map the other 90%.”
The coral reef is located between the Brazil-French Guiana border and the Brazilian state of Maranhão at depths from 30m to 120m.
Main image: A barrel sponge at a Verde Island coral reef. This invertebrate is just one of many species discovered at the Amazon reef. © Howard Chew/Getty