Reef conservation typically hinges on the health of corals in translucent, tropical shallows and photosynthetic algae that live mutualistically within them, producing the nutrients the corals need in order to grow. In northeastern Brazil, however, scientists are pushing for protection of a different type of reef, one that lies off the mouth of the Amazon River. This relatively recently discovered, little-studied reef lies in deeper, murkier waters. Its main building blocks are tennis-ball-sized clusters of red algae living on the nutrients that the river pumps seaward.

The Amazon Reef stretches some 1,000 kilometers (600 miles) from French Guiana, where it lies about 100 kilometers off the coast, southeast into the waters off Brazil. There, it sits some 230 to 250 kilometers (140 to 155 miles) offshore, running parallel to the coastline of the northeastern states of Amapá and Pará, where the mouth of the Amazon River is located, to a point off the state of Maranhão. Compared to a prototypical coral reef, the Amazon Reef receives substantially less sunlight given the greater depths—from 70 to 220 meters (230 to 720 feet)—and the relative turbidity of the water enveloping it.

Early last year scientists sponsored by the environmental group Greenpeace used a manned mini-submarine to conduct the first filming of the reef, the only one known to be located off the mouth of a major river. The goal was to better understand the biome and how it might be affected by spills from offshore oil wells that three companies—Total of France, United Kingdom-based BP and Brazil’s Queiroz Galvão Group, hope to drill nearby. But scientists say that the unusual structure might also teach them how reef systems elsewhere will react to the escalating impacts of climate change.

“The Amazon Reef presents important research opportunities because it is growing under marginal environmental conditions, such as strong sedimentation, low light and low-alkaline seawater,” says Rodrigo Moura, a marine biologist and lead author of an April 2016 study, published in the scientific journal Science Advances, confirming the reef’s existence. “[It] can help us forecast what could happen to coral reefs if climate change causes oceans to absorb carbon dioxide and become less alkaline and sea levels to rise and erode coasts, filling the seas with sediment that increases their turbidity. Such studies can alert people about massive marine biodiversity losses that will occur as the impacts of climate change become more pronounced.”

Little-known reef

The reef’s existence had been suspected in the 1960s, based on geological surveys that had been conducted in connection with the delineation of exclusive economic zones. (Often referred to as EEZs, these zones are marine areas over which the U.N. Law of the Sea treaty allows countries to assert special rights of exploration and resource-use.)

Physical evidence didn’t come until 2012-14, when Brazilian and U.S. researchers sailed over portions of the reef and used buckets to dredge up samples of red algae, sponges, corals and tropical fish. In the same period, the scientists took acoustic soundings that traced the structure’s full, 600-mile length. In 2016, they described their findings in a Science Advances paper that was seen as the first scientific confirmation of a reef off the mouth of the Amazon.

Along the Amazon Reef, red algae feed on organic matter from the river sediment and mineralize calcium carbonate in seawater to form the reef structure. The reef also includes sponges and some corals, which are sparse on account of the relatively scant penetration of sunlight. The ecosystem also contains lobsters, crabs and a large variety of tropical fish, which feed on the sponges and marine worms that use the algae as habitat. Nils Asp, a Brazilian oceanographer and coastal geologist, agrees with Moura that the reef offers a rich research opportunity.

“The Amazon Reef provides a picture of how coral reefs might look as climate change worsens and threatens their survival,” says Asp, who coauthored the Science Advances study and took part in last year’s submarine dives. “And it is growing under special and extreme conditions that create a unique biodiversity, some of whose organisms have not been studied and could be used to develop biotechnological medical advances.”

In August 2016, Greenpeace cited the Science Advances study in raising concerns about plans being drafted at the time for offshore oil drilling not far from the reef. The international green group then funded the submarine dives, conducted in January and February of 2017, to film and photograph the reef. The project involved four of the 39 researchers who had participated in the Science Advances study. During 15 dives, they captured images of 61 species of sponge and 73 species of fish, as well as spiny lobsters and sea stars. Scientists say they believe that previously unknown fish species were likely spotted during the dives, though this couldn’t be confirmed since they didn’t capture the fish.

Some of these scientists plan to conduct further underwater observations from April 1 to May 22, this time using a remote-controlled submarine. Last year’s dives occurred along a portion of the reef off the Brazilian state of Amapá, and were mainly meant to document the reef’s presence there. The upcoming expedition, also sponsored by Greenpeace, will be conducted along the entire length of the reef.

The remote-controlled submarine—called an ROV, the acronym for Remotely Operated Vehicle—will collect biological samples, and will carry cameras and sonar equipment with which to map the reef and confirm its size. Researchers say the reef could be 10 times larger than the current estimate of 9,500 square kilometers (3,700 sq. miles). Aside from following the reef along the continental shelf, the submarine will be guided beyond the shelf to look for plankton-consuming, deep-water corals capable of living as far as 2,000 meters below the ocean’s surface. 

“These ROV dives, like the submarine dives, will increase our understanding of reef fauna and flora, which is a priority for biodiversity conservation in the southern Atlantic,” says expedition member Ronaldo Francini-Filho, a marine biologist and professor in the department of ecology at the Federal University of Paraíba state who also took part in last year’s dives. “[Participating scientists] could find and collect previously unknown endemic reef species. If the reef is impacted, say by an oil spill, we could forever lose these species, and the scientific knowledge they hold.”

Offshore drilling plans

Energy companies made their plans known for nearby offshore oil development in concession contracts they signed in 2013 and in documents they submitted subsequently to Ibama, the enforcement arm of Brazil’s Environment Ministry, to apply for drilling permits.

The contracts targeted a deepwater oil-exploration area that the government calls the Mouth of the Amazon Basin and is estimated to contain some 15.6 billion barrels of oil. Located under an area of ocean floor where water depths exceed 1,000 meters, the oil fields range from 28 to 160 kilometers (17 to 100 miles) from the reef.

Three companies won concessions. Total was awarded five blocks; BP landed one block; and the Queiroz Galvão Group, a Brazilian industrial conglomerate, received one block. All three companies have applied to Ibama for drilling permits, but thus far no applications have been approved.

Total made no reference to the Amazon Reef in the initial environmental-impact assessment it submitted to Ibama in March 2015 to secure drilling permit. Ibama later asked Total repeatedly to address potential impacts on the reef, which the company ultimately did in a revised assessment that it submitted in August 2016 and in yet another revised version provided to Ibama in August 2017.

Shortly after receiving the 2017 revision, Ibama President Suely Araújo announced that Total’s documentation was still not complete. She gave the company one more chance to file the complete information, saying that if it fails to do so, her agency will “shelve” the application.

Experts that Greenpeace commissioned to review Total’s first revised assessment said the company failed to refer to the Amazon Reef in key studies, among them a vulnerability analysis that forms part of the company’s proposed spill-response plan. The revised assessment did, however, say that the northern portion of the Mouth of the Amazon Basin, where all five of Total’s oil-concession blocks are located, “presented a probability of being impacted by oil, albeit in a restricted area.” A copy of the first revised assessment reviewed by EcoAméricas, meanwhile, says that the probability of impacts on a restricted area of the reef in the event of a spill ranged “from up to 20.93% in the summer to up to 30.33% in the winter.”

According to Total’s assessment, an initial deepwater exploratory well will be drilled 200 kilometers (124 miles) offshore in a block 28 kilometers (17 miles) from the reef, and a second well will be sunk 38 kilometers (24 miles) from the reef. BP’s concession block is 160 kilometers (100 miles) offshore and 35 kilometers (22 miles) from the reef.

In response to questions from EcoAméricas about possible spill impacts from its deepwater wells, Total said that it “has performed an extensive environmental characterization in the area where its blocks are located,” adding: “And our EIA also addresses the risk of an oil spill and proposes a response to it. Ibama is still analyzing the study and will only issue the license if they consider the risk acceptable. Drilling operations will start only when we have the final authorization from Ibama.”

Ibama is expected to decide on the Total license request by May.

For its part, BP responded to similar questions from EcoAméricas by saying only: “We have a concession contract commitment to drill one exploration well in the block by August 2018, subject to approval by the appropriate Brazilian authorities.”

Drilling called incompatible

Environmentalists and Amazon Reef researchers are sounding the alarm about the proximity of the Total and BP blocks to a vast, little-understood reef ecosystem.

“The Amazon Reef, a new and unique ecosystem, is already under threat from Total, BP and an oil industry willing to risk spills and worse in their pursuit of fuel,” says Sara Ayech, an oil-issues campaigner at Greenpeace’s London office. “Trashing one of the few unexplored wonders of nature in that pursuit would be unforgivable. Greenpeace shares the concerns expressed by Brazil’s environmental experts, that allowing oil companies to drill in delicate environments without a proper understanding of the area presents an unacceptable risk and would show shocking negligence.”

Says Thiago Almeida, climate and energy campaigner for Greenpeace Brazil: “Given what a disastrous impact any oil spill could have on this one-of-a-kind reef, a 30% risk of a spill’s impacting it is unbelievably and unacceptably high, too high to grant an oil company a license to drill in its vicinity.”

Both Greenpeace and Asp, the coastal geologist, point out another potential danger of an oil spill near the reef—the possibility that a slick could reach the coast, which boasts the world’s longest continuous belt of mangrove forests, a 7,600 square-kilometer (2,900-sq.-mile) ecosystem stretching from the northeastern Brazilian state of Maranhão to Venezuela.

Says Asp: “An oil spill near the Amazon Reef could be catastrophic to both it and the long belt of coastal mangrove forests, an essential breeding ground for fish, crustaceans, ocean mammals and sea birds.”