Sep 30

World Rivers Day is an annual global celebration of the world’s waterways, observed on the last Sunday in September. Established in 2005 by the internationally renowned river conservationist Mark Angelo, World Rivers Day highlights the global importance of rivers and aims to increase public awareness and encourage greater stewardship of rivers around the world.

River running through the Northwoods, Wisconsin

River running through the Northwoods, Wisconsin

Celebrating World Rivers Day

Millions of people in more than 60 countries celebrate World Rivers Day. Here at ARKive, we’ve joined in by talking to Kevin Smith, a Programme Officer with the IUCN Freshwater Biodiversity Unit, to find out more about the importance of rivers and the main issues they face.

‘Ribbons of life’

Rivers underpin many freshwater ecosystems and play a critical role in sustaining the lives of thousands of different species and habitats worldwide. Despite their importance, rivers and their associated freshwater ecosystems are actually extremely rare. Only 3% of the world’s water is fresh water, and freshwater ecosystems account for less than 1% of the planet’s total surface area.

Riverine habitat

Riverine habitat

According to Kevin, “Rivers – and freshwater habitats in general – are real hotspots of biodiversity. They may only cover 1% of the Earth’s surface, but they support almost 10% of the world’s known species. These ribbons of life also provide livelihoods and economic benefits to billions of people across the world through what are known as ‘ecosystem services’ such as fisheries, water filtration or even tourism.”

Rivers shape the landscape; act as drainage channels; and transport fresh water and nutrients to lakes, wetlands and other freshwater habitats before eventually flowing out to sea. They provide the stage for some of nature’s most spectacular events, such as the annual migration of salmon from the sea to their spawning grounds upstream. Rivers, and the fresh water they contain, are also vital to human wellbeing, providing the water we drink, as well as sources of food, recreation and energy.

Sockeye salmon jumping up waterfall to spawn

Sockeye salmon jumping up waterfall to spawn

Rivers in danger

Many of the world’s rivers are also in danger, often due to human development, pollution and climate change.

Rivers and other freshwater habitats are among the most threatened on the planet. Rivers are highly interconnected systems that can transport threats to biodiversity, such as pollution or invasive species, long distances. The species that inhabit rivers also have limited dispersal ability as they can rarely escape onto land to avoid such threats,” says Kevin.

Fewer than 70 of the world’s 177 longest rivers remain free of man-made obstructions, such as dams and hydroelectric power plants.

Rivers have also been heavily modified, and have been used and viewed as a public resource (for water or waste dispersal) to be exploited for many years,” explains Kevin. “Because of this, many threats exist to rivers and their biodiversity, from agricultural and industrial pollution, excessive water extraction and dams, to the introduction of non-native and invasive species and the overharvesting of biodiversity.

Spotlight on: the world’s longest rivers

As it’s World Rivers Day, we’ve taken the opportunity to take a look at four of the world’s longest rivers and highlight some of the amazing species that inhabit them, as well as the threats that these magnificent rivers face.

Mississippi River3,902 miles (6,275 kilometres)


Pair of young North American river otters on log

Pair of young North American river otters on log

The largest river in North America, the Mississippi gets its name from the Native American Chippewa tribe’s words ‘mici zibi’, meaning ‘great river’. The Mississippi River provides food and shelter for hundreds of different species, from freshwater fish to mammals, reptiles, amphibians, insects and birds, including the 8,000,000 ducks, geese, swans and wading birds that use the river as a flyway.

The upper Mississippi region is home to one of the largest populations of nesting bald eagles in the United States, while the river also provides important habitat for the playful North American river otter. The otter was once common along the Mississippi, but unregulated trapping and habitat loss around a hundred years ago pushed this species towards the brink of extinction. Fortunately, improvements in water quality, trapping regulations and reintroduction efforts in the 1980s have enabled the otter population to grow and recover in recent years.

Yangtze – 3,917 miles (6,300 kilometres)

Baiji at waters' surface

Baiji at waters' surface

The Yangtze is the world’s third longest river, rising in west-central China and flowing across the Tibetan Plateau until it reaches the East China Sea near Shanghai.

The Yangtze River Basin has remarkably high levels of biodiversity and its waters are home to some amazing aquatic creatures, including the Yangtze finless porpoise and the baiji, the rarest cetacean in existence. The forests of the upper Yangtze are the only place where the giant panda can be found in the wild, while the central parts of the river and its lakes are known to be important for many migratory bird species, including an estimated 95% of the world’s Siberian crane population.

The Yangtze River Basin itself is faced with enormous environmental challenges and is being placed under severe strain as a result of growing pressures from the region’s expanding population and rapid economic development. The impacts of climate change, agriculture, pollution and infrastructure development are having hugely detrimental effects on the river’s species, habitats and the wider ecosystem.

Amazon – 3,980 miles (6,400 kilometres)

Amazonian manatee swimming beneath aquatic vegetation

Amazonian manatee swimming beneath aquatic vegetation

The world’s largest river by volume, and considered by many to be the longest river in the world, the Amazon begins in Peru and flows through Brazil where it reaches the Atlantic Ocean.

The drainage basin of the Amazon River supports the magnificent Amazon rainforest, home to an incredible diversity of animals and plants, from the curious Amazonian manatee to an array of colourful birds and insects, including over 4,000 species of butterfly. Despite its exceptional biodiversity, the Amazon River, as well as much of the surrounding rainforest, is under threat. The river itself is faced with a number of issues, including the construction of dams in areas of high conservation value.

Nile 4,135 miles (6,650 kilometres)

Nile crocodile close-up

Nile crocodile close-up

Traditionally considered to be the longest river in the world, the Nile flows north through eastern Africa to where it empties into the Mediterranean Sea. The name of this imposing river is derived from the Greek word ‘neilos’, which means ‘river valley’.

As well as supporting a large number of species in its waters and along its banks, the Nile is depended on by more than 300 million people for their water supply and the irrigation of seasonal crops. Reptiles, such as the Nile crocodile, flourish in the waters of the Nile, while fish, birds and mammals also rely on the river as a source of food and water.

Find out more about World Rivers Day.

Learn more about the IUCN Freshwater Biodiversity Unit.

Helen Roddis, ARKive Education Officer



RSS is the place for films, photos and facts about endangered species. Subscribe to our blog today to keep up to date!

Email updates

Sign up to receive a regular email digest of Arkive blog posts.
Preferred frequency:

Arkive twitter

Twitter: ARKive