Amazon Reef facts for kids
The Amazon Reef is a huge system of coral and sponges. It's found in the Atlantic Ocean, off the coasts of French Guiana and northern Brazil. This reef is one of the biggest known reef systems in the world. Scientists believe it stretches for over 965 kilometers (600 miles) and covers more than 9,320 square kilometers (3,600 square miles). Its discovery was announced in April 2016, after a big ocean study in 2012. However, there were clues about a large structure near the Amazon River's mouth as early as the 1950s.
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How the Amazon Reef Was Found
In the 1970s, a biologist named Rodrigo Moura studied fish on the continental shelf. He wanted to find the reefs where these fish lived. When he found fish usually seen on coral reefs near the mouth of the Amazon River, he thought there must be a lot of different life forms underneath. This was a big clue!
Many years later, some students from the University of Georgia looked at Moura's old research. His article didn't have exact GPS coordinates. So, they used his sound wave data and sea floor samples to try and find the reef. Once they thought they had found it, they used a special tool to scoop up samples from the bottom. This helped them confirm its location. It took about three years to find the reef before they could officially announce its discovery.
The Amazon River is huge, carrying about 20% of the world's fresh water into the ocean every day. Because the Amazon Reef is right at the mouth of this giant river, it has less variety of life compared to other reefs. This is due to the constant flow of fresh water and mud.
Where the Reef Is and What Lives There
The Amazon Reef is a mix of coral and sponges. It's estimated to be over 9,320 square kilometers (3,600 square miles) in area and more than 965 kilometers (600 miles) long. This makes it one of the largest reef systems on Earth. The reef stretches up to 120 kilometers (75 miles) offshore. It lies in waters that are usually 30 to 120 meters (100 to 400 feet) deep.
It's very unusual for a reef to exist at the mouth of a huge river like the Amazon. This is because big rivers bring lots of fresh water, which lowers the saltiness of the ocean. They also carry a lot of mud and dirt, which can block sunlight. Corals usually need clear, salty water to grow well.
The Amazon Reef survives because it's deep. It sits below the layer of fresh water and mud that flows out from the Amazon River. This deep location helps it avoid the harsh conditions closer to the surface.
Most of the reef is made of rhodolith. These are types of red algae that look a lot like coral. Even though it's not as diverse as some other famous reefs, scientists have found many amazing creatures here. So far, 61 types of sponges and 73 types of fish have been identified. There are also different kinds of corals and starfish, including staghorn corals and spiny lobsters.
Some coral species found here are similar to those in the Caribbean Sea. This suggests that corals might have traveled from the Caribbean to the Amazon Reef. Scientists also think the reef might act like a "stepping stone." It could help species move from reefs in southern Brazil up to the Caribbean.
The Amazon River's flow greatly affects the reef's life. The northern parts of the reef are often covered by the river's muddy water for about half the year. This creates a "shadow zone" where less light reaches. These areas have more sponges and meat-eating creatures. The southern parts of the reef are covered by the river's plume for only about three months a year. These areas have more diverse coral life, where photosynthesis (making food from sunlight) can happen.
Scientists believe that tiny, single-celled organisms are very important to the reef's health. They provide food for sponges, corals, and other animals. Researchers even describe this reef system as a new type of biome, which is a major living area.
The Scientific Expedition
Hints of a reef system in the Amazon Delta first appeared in the late 1950s. A U.S. survey ship collected sponges from the ocean floor there. Later, in 1977, reef fish were seen in the area. In 1999, Caribbean-native coral species were found in small areas near the Amazon Delta.
However, no major study happened until 2012. An international team of over 30 oceanographers, led by Rodrigo Moura, went to explore the area. They used a research ship called the RV Atlantis. Their survey was based on findings from the 1970s, including a rough map of possible reef locations.
The team used special tools like acoustic sampling to find potential reef spots. They confirmed their discovery by scooping up samples of corals, sponges, and other reef creatures from the ocean floor. Their exciting findings were published in a science journal called Science Advances in April 2016.
Some of the waters around the Amazon Reef are very murky due to the Amazon River's muddy plume. The reef's biology depends on where this plume is. The southernmost part of the reef gets the most sunlight because the plume only covers it for three months a year. This is where sea life can make its own food. The northern part is covered by the plume for six or more months. This area has more sponges and meat-eating sea life. Scientists found that the reef has a mix of life similar to both Brazilian reefs and the Caribbean reef.
Threats to the Amazon Reef
Since its discovery, the Amazon Reef has faced several dangers. These include pollution and overfishing. Also, rising ocean acidification and warmer ocean temperatures from climate change are a threat. These issues affect many reefs around the world, like the Great Barrier Reef in Australia.
A more immediate danger comes from oil exploration projects. In the past ten years, the Brazilian government has sold many licenses to oil companies to explore for oil in the region. Some of these areas are very close to or even on the reef itself. Twenty of these areas are already producing oil.
Climate Change Effects
The Amazon Reef is at risk of coral bleaching. This happens when corals get stressed by warm water and lose their color. It's a big problem for many reefs globally, including the famous Great Barrier Reef.
See also
In Spanish: Arrecife de coral del Amazonas para niños
