Freshwater Ecosystems

The vital importance of freshwater ecosystems for the whole planet

Autumn colours, Setesdal, Aust-Agder County, Norway (2014) by © GRID-Arendal/Peter ProkoshOriginal Source:

What are freshwater ecosystems?

Freshwater ecosystems are an important variety of aquatic areas such as rivers, lakes, streams, or ponds. These ecosystems are essential for the survival of many species, including ours, as they provide large quantities of drinkable and irrigation water.

Bileca Lake, Bosnia and Herzegovina (2014) by © GRID-Arendal/Peter ProkoshOriginal Source:

Where does freshwater come from?

Every day, a large amount of water evaporates from the ocean. 
When transformed into gas, the water, purified from its salt, rises to the atmosphere where it is changed into clouds. The wind moves the clouds over the land where freshwater is delivered as rain or snow:  this is the water cycle. 

Coastal Archipelago Park of the South Coast ("Sørlandet") of Norway, Mute Swans, Hvaler islands (2016) by © GRID-Arendal/Peter ProkoshOriginal Source:

Where can we find freshwater ecosystems?

Freshwater ecosystems can be found all over the world except in the Poles where water freezes, because of cold temperatures, and in deserts where water evaporates immediately.  

Lioness having a drink in the Kgalagadi Transfrontier Park between South Africa and Botswana (2016) by © GRID-Arendal/Yannick BeaudoinOriginal Source:

Importance of freshwater ecosystems

Freshwater ecosystems sustain other surrounding ecosystems by providing water to many species. Some animals cover hundreds of kilometres to reach freshwater spots, where they can also find large quantities of food.

Harvesting water in Peru - MAX HIDALGO QUINTO - UNEP Young Champion of the Earth, Latin America (2020) by © UNEPThe United Nations Environment Programme (UNEP)

Water and the triple planetary crisis

Lake Naivasha, Kenya 2 (2015) by © GRID-Arendal/Peter ProkoshOriginal Source:

Flora in freshwater ecosystems

Many species of aquatic plants and algae live in rivers and streams. If the water is clear enough, they can receive sunlight and grow under the water. Some other species such as water lilies are both under and over the water to better benefit from the sun.  

Lake at the Napo Wildlife Center, Yasuni National Park, Ecuador (2014) by © GRID-Arendal/Peter ProkoshOriginal Source:

Freshwater ecosystems are also very favorable to many tree species that need important quantities of water such as willows and river birch. The type of plants thriving alongside freshwater depends a lot on the climate conditions and the quality of the soil.  

Hippos cooling down in the Okavango Delta, Botswana (2016) by © GRID-Arendal/Yannick BeaudoinOriginal Source:

Fauna in freshwater ecosystems

All kinds of animals can be found in freshwater ecosystems, including mammals such as hippopotamuses, birds such as swans, and reptiles such as alligators.

Strawberry Poison Dart Frog (Dendrobates pumilio), National Park Tortuguero, Costa Rica (2012) by © GRID-Arendal/Peter ProkoshOriginal Source:

Of course, freshwater ecosystems are also home to many fish, insects, and amphibian species. Water is vital to amphibians as they first grow as aquatic larvae before undergoing metamorphosis to become adults.  

Land and Sky in the Moremi Park, Botswana (2016) by © GRID-Arendal/Yannick BeaudoinOriginal Source:

Benefits of freshwater ecosystems for humans

Healthy freshwater environments provide us with food as well as drinkable and precious irrigation water for crops. They are used in manufacturing and transport industries and can produce significant amounts of energy. 

Railways under water, Rhone River, Lyon, France (2022) by © Pierre FlecheuxThe United Nations Environment Programme (UNEP)

Freshwater ecosystems: a human habitat?

The first human settlements and villages were built alongside rivers as they provided food and drinking water. Over the centuries, these same villages became the towns we all know today. These important rivers are rarely considered ecosystems.

Ölfusá River Mouth, South Iceland 2 (2013) by © GRID-Arendal/Peter ProkoshOriginal Source:

Main threats to freshwater ecosystems

Freshwater ecosystems are very vulnerable to human activities:   
- Pollution   
- Climate change  
- Change in the water cycle   
- Sea level rise   
- Human infrastructures
- Overuse of water 

Pollution in the Nairobi river, Kibera, Kenya 2 (2018) by © GRID-Arendal/Peter ProkoshOriginal Source:

Pollution of freshwater

Pollution refers to the addition of any substance to the environment at a faster rate than it can disappear. Freshwater ecosystems are very vulnerable to biological, chemical, and physical pollution created by human activities.  

Greater flamingo (Phoenicopterus ruber), Elementaita Lake, Kenya (2015) by © GRID-Arendal/Peter ProkoshOriginal Source:

For our sake, as well as the rest of the planet, urgent action is needed to avoid the dramatic impacts of human activities on freshwater ecosystems. Like every species on this planet, our survival depends on this water!

Autumn colours, Håhelleren DNT cabin, Setesdal Vesthei - Ryfylkeheiane Landscape Conservation Area (2014) by © GRID-Arendal/Peter ProkoshOriginal Source:

Summer Stream, Stellenbosh, South Africa (2022) by © Pierre FlecheuxThe United Nations Environment Programme (UNEP)

Additional learning resources

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The United Nations Environment Programme (UNEP), Europe Office

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