Washington State University
Dr. Universe: How can plants help rivers?
Jaydon, 9, Charlestown, Indiana
Rivers are great places for kids to explore. With an adult and a safe body of water, you can wade, swim, splash and enjoy the incredible number of animals that inhabit the river, as well as all the flora. Many types of plants grow around rivers. You have already guessed how important they are for keeping rivers healthy!
To learn more, I spoke to my friend Alex Fremier, an associate professor at Washington State University’s School of the Environment who works with the State Water Research Center. from Washington.
Fremier studies areas called watersheds. The catchment area of a river is made up of all the land where rain and snow fall and flow down hills and through streams into the river.
Plants in a watershed absorb water before it reaches the river. They also help filter out pollutants in the water that goes there.
“If you took all the plants out, the water would fall on the ground and dislodge that soil, and that soil would get into the streams and pollute them,” Fremier said.
Some rivers have a lot of dirt, like the muddy Mississippi, while others are clearer. Anyway, animals that live in a river are used to a certain amount of dirt in the water. Plants in the watershed help keep this amount stable, which keeps animals healthy.
Rain and soil can also bring other pollutants. Plants help filter pesticides or fertilizers from crops and chemicals from roads.
Plants that grow along the banks of a river are also useful. We call these plants “riparian” (RY-PAIR-EE-AN). Riparian plants are the last filters between land and water. They also hang above the water, keeping the river cool. A constant temperature is important for river animals.
For example, says Fremier, “salmon need cool, clean water, and if the sun hits the surface of the water, that water will warm up.”
Finally, there are plants growing in the river. If you’ve ever touched river rocks, you’ve smelled the slimy brown or green algae (AL-GEE) growing there. Algae are plants! They draw chemicals like nitrogen and phosphorus from the river water to help them grow.
Fremier encourages children to think about all the ways plants help rivers by observing algae. The next time you are near a river, pick up a stone. Watch the algae and other tiny plants growing on the surface. Then flip the boulder and look back. If the water is clean, you will see tiny baby bugs.
Algae and insects are both part of the river’s ecosystem, as are the tall trees in the watershed, the ferns that grow along the banks, and the salmon that swim in the water. A healthy ecosystem needs multiple parts, working together.
People are also part of the river’s ecosystem. Keep being curious and asking questions, and you can be part of the great team that helps keep the water clean for all the wonderful things that live in and near a river.
Adults can help children submit a question at askdruniverse.wsu.edu/ask