Freshwater habitat

Looking at pictures of Earth from space, it’s easy to think that water is plentiful. After all, water covers 70% of our planet. However, fresh water—the stuff we drink, bathe in, irrigate our farm fields with—is incredibly rare. Only 3% of the world’s water is fresh water, and two-thirds of that is tucked away in frozen glaciers or otherwise unavailable for our use. Clean freshwater is a luxury in many parts of the world. Without a clean source of fresh water, people are exposed to diseases, such as cholera and typhoid fever. Two million people, mostly children, die each year from waterborne diseases alone.

Freshwater ecosystems account for less than 0.01% of the planet’s total surface area but they support more than 100,000 species, a list that includes more than just fish. Worms, mollusks, crayfish and insect larvae burrow into muddy lake or creek bottoms. Reeds and rushes along the shores shelter frogs and newts. Birds and mammals nest and feed in wetland vegetation. Even cave systems can be full of unique life, including blind fish and amphibians.

But these freshwater systems are now among the most endangered habitats in the world, due to human development, pollution, and climate change. Fewer than 70 of the world’s 177 longest rivers remain free of man-made obstructions. Also, more than half of the world’s wetlands have disappeared since 1900, a particular concern because these places serve as nature’s water treatment facilities—cleaning water of chemicals and other pollutants. Development, logging, pollution, agriculture and poor management put freshwater systems—and the water they produce for people—at risk.