The Great Amazon Reef
Not many people have heard of it as it was only discovered in 2016. This reef lies some hundred kilometers off the coast of French Guyana and reaches all the way to the mouth of the Amazon river. The remarkable thing about the Great Amazon Reef is that it is not located near the surface, like the other reefs that we know. This one is “on the ocean floor, right on the edge of the continental shelf, what must have been a coral reef during the last glacial period is today submerged at a depth exceeding a hundred metres, in total darkness,” explains Serge Planes, a biologist at the Centre for Island Research and Environmental Observatory (CRIOBE). The Great Amazon Reef is a mixture of sponges, corals, big walls of crusted coralline algae, and rhodoliths - rock-like nodules of red algae that cluster into giant beds and are important to biodiversity and act as carbonate deposits with an important role in the global carbon cycle.
Greenpeace explored the reef in 2017 with a team of divers to collect biological samples. Diving this deep (the reef can be found between 60 and 220 meters) is already difficult, but the waters here are very turbid due to sediment coming from the Amazon and have high concentrations of plankton. In the first few meters the water is very cloudy making visibility almost zero, and below 70 meters daylight hardly comes through. To add to the difficulties, on the ocean floor it is constantly ´raining´ marine snow, white flakes produced by decomposing plankton. It is not yet known how big the Great Amazon Reef is exactly, but it estimated it is spanning an area of 56,000 square kilometers.
The biodiversity found on and around the reef is a mix of species commonly found in the coral reefs of the Caribbean and animals that are more typical of sandy sea beds and abyssal plains. A lot of research still needs to be done to be able to have a good overview of this ecosystem, but at this moment we already know that it’s a very unique and vulnerable environment. Olivier Van Canneyt, a biologist at the PELAGIS observatory, believes that the high level of biodiversity is due to the mixing of sea water with fresh water from the Amazon, and from French Guiana’s rivers, like the Oyapock and Maroni.
Despite its environmental importance, the Great Amazon Reef is threatened by the expansion of oil and gas exploration projects in the region. An estimated 15.6 billion barrels of oil lies underneath the reef which is of course interesting for oil companies. In 2018, some scientists who were supported by politicians and oil industry professionals began to publicly question whether the reef even existed, because, they argued, that the reef was dead and that it would be impossible for anything to grow under these harsh conditions. However, a team of Brazilian scientists, led by Michel Michaelovitch de Mahiques, an oceanographer from the University of São Paulo, proved the opposite. The team used radiocarbon dating on samples from throughout the reef to reconstruct its evolutionary development. “We needed to convince deniers that the reef is full of living organisms,” says Mahiques. They found relatively young rhodoliths and sponges from northern, central, and southern sections of the reef, showing that the reef is alive and growing.
Oil company Total was denied permission to drill for oil in the region and in August it notified its partners that it is resigning from its role of operator of five exploration blocks in the Foz do Amazonas Basin. But this doesn’t mean that the reef is not under threat anymore. Brazil’s regulator ANP (National Agency of Petroleum) will now open a six-month period in which a new operator will be appointed. Thiago Almeida, a climate and energy campaigner at Greenpeace Brazil is concerned about Brazil´s current government under Bolsonaro. This government “has such an anti-environmental agenda that we are worried that it will give the license no matter the size of the threat.”
Sources
Pictures: CNRS
