Amazon River Ecosystem and Biodiversity
The Amazon River is the greatest river of South America and its biodiversity the richest of any river in the world. Its waters are populated by 2,500 different species of fish, scientists believe that there are many more that have not been identified yet. Mammals, amphibians and water snakes also call the Amazon River home. The river has been a source of protein for the local population for thousands of years and a source of fresh water.
The Amazon River and its tributaries have depleted and eroded the land removing almost all its nutrients and leaving an extremely poor soil. How does the Amazon rainforest exist? It exists because of nutrient recycling. As plants die insects and microbes decompose them releasing nutrients that support new plants. Near water sources as plants absorb the energy from the sun vegetation becomes dense but trees do not grow very tall. Many animals that live in the Amazon River depend on the recycling of nutrients as they feed from plants and algae. This system of recycling has sustained life in the Amazon rainforest for millions of years.
Animal life support each other in the Amazon River by serving as food to other animals above the food chain. Their bodies carry nutrients that eventually serve as fertilizer, feeding the forest and the fauna of the Amazon River ecosystem.
Amazon River Animals
Some species of animals are exclusively found in the Amazon River and many of them are in danger of extinction. For the last 20 years the governments of Peru and Brazil along with conservation organizations, local businesses and indigenous people have been working together to protect endangered species for the enjoyment of the world and future generations.
The following animals are unique to the Amazon river and its tributaries:
The pink dolphin or bufeo (Inia geoffrensis)
One of the most endangered species in the Amazon River is the pink dolphin or bufeo thought to be extinct more than twenty years ago. They are very rarely seen and are found only in the Amazonian rivers around Iquitos. Their pink color is due to blood capillaries near its skin and unlike other dolphins they have a hump instead of a fin and a long bottle nose snout instead of a short one. A distinctive characteristic of the pink dolphin is that they can turn their neck 180 degrees due to an unfused vertebra in its neck.
The average pink dolphin is 8.25ft to 9.75ft long (2.5 to 3 meters) and weights 200lbs (90 kilos). Males are usually larger and heavier. Their diet consists of fresh water fish, crustaceans and turtles. The pink dolphin is a solitary creature unlike their more social relative, the tucuxi.
Pink dolphin or bufeo
The giant river otter
The giant river otter is considerably larger and heavier than other river otters at over six feet long and an average of 210 pounds. This species of river otters is very social and communicative, they are rarely found alone and communicate through high pitched screeches. They live in groups of five to ten and eat mostly fish.
The giant river otter is a highly endangered animal in the Amazon River, only 2,000 to 5,000 remain in protected areas in the Amazon basin. Its population once extended from Venezuela to Argentina but because of fur hunting and habitat destruction its numbers have dramatically decreased. These mammals can be seen at the Manu National Park and at the Pacaya-Samiria National Reserve.
Amazon giant river otter
One of the most recognizable Amazon River fish is the piranha. These are small fish with very sharp teeth which local indigenous people use as cutting tools. These small fish are an important part of the Amazon River’s ecosystem as they eat weak or dead fish and dead animals that would otherwise pollute the waters of the Amazon River. The number of piranha species is estimated to be between 30 and 60. Only five of them pose danger to humans; the red bellied piranha or Pygocentrus nattereri, white piranha or Serrasalmus rhombeus, Serrasalmus Piraya, silver piranha or Serrasalmus Ternetzi and Serrasalmus Hollandi.
Piranhas help keep rivers clean
Amazonian manatee (Trichechus inunguis)
The Amazonian manatee is the largest mammal living in the Amazon River at over 1,000 pounds (454 kilos) and 9 feet (3 meters) long. They are found in the northern Amazon River Basin and its tributaries and are locally known as “seacows”. Their skin is thick, wrinkled and grey in color. The manatee is an herbivore so it depends heavily on vegetation near the rivers, over the years soil erosion from deforestation has been affecting its food supply making it scarcer. During the wet season the manatee can eat up to 110 pounds a day to build up reserves for the dry months.
For centuries the Amazonian manatee has been hunted by local Indians who consumed their meat and used their oil and fat. Demand for the animal expanded making it commercially profitable. Another factor affecting its population is accidentally getting caught in commercial fishing nets. They are classified as vulnerable in the endangered species list.
Amazonian manatee or seacow
Tucuxi (Sotalia fluviatilis)
The tucuxi is locally known as bufeo gris or bufeo negro. Tucuxi, pronounced “too-koo-shee” is one of the two species of river dolphin that live in the Amazon River and its tributaries, the other one is the pink dolphin. The tucuxi looks like a bottlenose dolphin with dark gray to light gray coloration but much smaller in size. On average a tucuxi grows between three to five feet long and their weight range is between 95 to 120 pounds. Their diet consists mainly of fish.
Tucuxi, one of the two species of river dolphins in the Amazon River.
Giant Amazon River turtle (Podocnemis expansa)
The giant Amazon River turtle is also known as Charapa turtle, Arrau turtle, Tartaruga-da-amazônia, or Araú. An adult turtle can grow to more than 3.3 feet (1 meter) in length and they often weight up to 200 pounds, female turtles have a larger shell and are heavier than male turtles. This species of turtles do not leave the water, only females do to lay their eggs on the sandy beaches and immediately return to the water. Once the eggs hatch the hatchlings get the attention of predators, mostly birds, it is believed that only five percent make it to the river. Because of their low survival rate this species has been included in the IUCN Red List of Threatened Species as a conservation dependent species.
Only five percent of hatchlings will make it to the river.
Giant Amazon River turtles from the Baltimore National Aquarium.
The arapaima is locally known as pirarucu or paiche and it is the largest freshwater scaled fish known to humans. It lives exclusively in the Amazon River and its tributaries and can reach a length of over nine feet long (almost 3 meters long) and weight over 440 lbs (200 kg). This species is a favorite among fishermen and have become a victim of overfishing. Because they come to the surface every five to fifteen minutes to breathe in air, they are easy to catch. Fishermen usually use harpoons and nets. Its meat is part of the culinary culture of the Amazon and is sought after for its taste. The arapaima is considered to be a living fossil that has not evolved for more than 20 million years and had no predators other than men.
According the BBC, errors in its classification has pushed the species closer to extinction. The latest taxonomic review was done over 160 years ago. Today they know that there are at least four species of arapaima. While some populations are increasing others are being overfished and driven to extinction.
Arapaima in captivity at the Vancouver Aquarium.
Electric eel (Electrophorus electricus)
The electric eel is an electric fish capable of generating electric shocks of up to 600 volts, five times the voltage generated by a U.S. household wall socket. This species live in the muddy waters of the Amazon River and its tributaries and it has a limited vision, therefore heavily relying on its electric field for hunting and self defense. Their bodies contain electrocytes, cells capable of storing power, and when threatened they will discharge electricity making them a feared predator.
The electric eel, despite its appearance, is not truly an eel (Anguilliformes) but a neotropical knifefish. It has a long, cylindrical, serpentine shaped body that grows to an average of 6 to 8 feet (1.8 to 2.5meters) long and weights 44 lbs (20 kilos). The electric eel can live up to 15 years and their diet consists mainly on fish, and in a smaller scale amphibians and birds.
The electric eel is not truly an eel but a neotropical knifefish.
The dwarf caiman (Paleosuchus palepebrosus)
Dwarf caimans are small crocodile reptiles and are distinguishable by the shape of their head. Their skulls are small and short and their upper jaws overlap the lower. The average length of a dwarf caiman is 5 feet (1.5 meters) long. Its body is covered in hard scales protecting them from predators. Their diet consists of fish and crustaceans. This species is not considered endangered.
The Amazonian dwarf caiman is also known as Cuvier’s dwarf caiman.
Anaconda (Eunectes murinus)
The green anaconda lives in the shallow waters of the Amazon. It is one of the largest species of snakes and the heaviest known to men. The anaconda can grow up to 30 feet (9 meters) long. Its color, green and brown, serves as camouflage in order to catch its prey. Anacondas are non-venomous constrictor snakes; they wrap around its victim and squeeze them to death. They eat small mammals, fish and rodents.
The green anaconda, a mighty constrictor.
These books have been used as bibliographical references:
More than three quarters of the Peruvian territory lies east of the Andes. The jungle or Selva has two parts, the high and the low Selva.
Mining and oil extraction are very controversial economic activities as they bring wealth and economic development but pollute the environment.
In terms of volume, the Amazon is the largest river in the world, it contains one fifth of the earth’s fresh water.
Between 1890 and 1920 the economy of the region suffer a boom due to the demand for its rubber.
Economic development is taking its toll among native Indians, many of them have fled deep inside the jungle, some have died of starvation and others have adapted to modern live.