River Habitat and Ecosystem
As water flows over the landscape, it carves channels that carry water and sediment to other larger water bodies, and eventually the ocean. In the process, it creates habitat, the physical foundation for living communities.
Habitat is where living things grow, feed, and reproduce. A river's habitat includes life in and around the water. In the river, there are fish, plants, animals, and numerous microorganisms that we can't see. On land, nearby trees, birds, and mammals, including humans, are all part of the river habitat.
An ecosystem is defined as the interactions among living creatures and their physical environment. This includes water, soil, climate etc. Aquatic ecosystems like a river's are varied and delicately balanced.
On the lowest level, all sorts of tiny organisms play a crucial role in maintaining the food supply for the entire ecosystem. These feeders, collectors, and grazers busily break down plant matter that grows on the stream bottom or falls from overhanging vegetation. There are snails at work processing the calcium in the water to build their shells, while salamanders sun themselves on nearby rocks. Trees and plants filter pollutants and sediments from run-off and provide shade for fish. Larger fish eat smaller ones and smaller predatory organisms parasitize larger fish. Birds, snakes, frogs, bears and other land animals, including humans, all come to the river for food and together make up the river ecosystem.
As each critter feeds, it produces waste which becomes food for some other type of feeder. In the stream environment, food is constantly being produced, consumed and recycled. Food provides the energy and raw material to make and grow living things; in many ways, the river ecosystem is a web of interactions centered around producing and consuming food.
Human activities that change the food source impair the life cycles of the creatures living in and around the river or stream. A change in river habitat from pollution, for example, will affect at least one type of critter. But because all living things in the river depend on one another, harm done to one creature will affect all others as well.
A major source of habitat disruption comes from the water run-off of nearby farms, industries, and our own homes and yards. When it rains, water rushes across our fields, streets and workplaces picking up dirt, containments and nutrients. This polluted man-made stream spills into our rivers threatening the delicate balance of the river ecosystem.
Sometimes we can tell when pollution is choking our rivers and streams. Many of us live beside a river that is obviously too polluted for swimming or fishing. Under the surface of these polluted waters, life has been dramatically altered. For example, in rivers and streams where there was once an abundance of fish and now only very little, land animals that fed on these fish will be forced to go elsewhere to find more suitable habitat. In situations like this one, we can see the important link between river ecosystems, habitat and our own impact.
There are thousands of river and watershed groups across the country devoted to monitoring river ecosystems and studying river habitats. Many members and volunteers routinely go out and check on the health of their local waters and the living creatures that depend on them. To get involved with your local group, click HERE (link to National Watershed Directory)
