Brazil, Amazon River – Researchers recently discovered an extensive reef system at the mouth of the Amazon river in Brazil. The unusual area of the discovery may explain why the ecosystem has passed unnoticed for so many years, although there were already some beliefs of its existence.
The reef is located in the Amazon plume, an area where the sweet water of the river mixes with the salty one from the ocean. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration and sedimentation. Those elements added up over time can cause an unfavorable condition for the reef, according to the paper published in the journal Science Advances.
Due to those conditions previously mentioned, it was thought unlikely for such life to be developed. Nevertheless, the team from a U.S. and Brazil collaboration research group proved the odds wrong. There were some studies back in the 1950s that suggested the presence of reefs in that area, but none pinpointed the reef bodies, dimensions, locations and compositions, said Senior author Fabiano Thompson to Discovery News.
“The paper is not just about the reef itself, but about how the reef community changes as you travel north along the shelf break, in response to how much light it gets seasonally by the movement of the plume,” said Patricia Yager, Sciences and principal investigator of the River-Ocean Continuum of the Amazon project.
In the far south, the reef gets more light exposure, meaning that many of the animals are more typical reef corals and organisms that photosynthesize for food. But as the team moved north, many of those became less abundant, comments Yager in the paper. In addition, the reef transitions to sponges and other reef builders that are likely growing on the food that the plume delivers, she added.
Reefs are already under threat
Even though the phenomenon was just discovered, its life is already in danger due to climate change and other man-made threats. The delicate shape of the common corals make them vulnerable to bleaching, pollution, mass predator outbreaks and more, according to Willem Renema from the Naturalis Biodiversity Center. Renema and his colleagues had previously studied why many reefs of the world over are faring so poorly.
Other important threat for the ecosystem is that in 2013, up to 125 portions of the river substrate were acquired by the petroleum industry for exploratory drilling, so the areas nearby to the Amazon plume are likely to be contaminated really soon.
However, once the region is properly analyzed and mapped, researchers can work for the creation of marine protected areas in places like the reef. Until now only 10 to 20 percent of the area have been studied. Although further research is needed to start making plans of creating a protective layer for reefs, the paper published on Science Advances is a step towards the right direction.
Source: Science Advances