Freshwater Ecosystems

Freshwater ecosystems include streams, rivers, lakes and ponds that have water and are surrounded by land. These waters move as rain and snow come and dry up.

With melting snow, lakes and rivers are supplied. Some springs flow underground, and the water comes from under the ground to keep the springs flowing.

Streams and Rivers

The streams and the rivers are oftentimes called lotic because they have waters that are always flowing.
A pond, for example, is sometimes still, but this is not so in rivers and streams.

The rivers and streams come in different sizes and some of them can be super small to super large.

There are many rivers that are considered major rivers in the world.

What Classifies a Stream and River?

In order for water to be classified as a stream or a river, there have to be certain factors. The factors include chemistry, flow, temperature, and light.


The chemistry of a stream or river has to be what types of soil and nutrients are in the river.


The flow of the water and how much strength it has helps to classify streams and rivers.

How fast and how slow a stream or river flow determines what type of life live in or around the waters.


The temperature of the river effects what type of marine and plant life grow or live around these types of waters.


Light is an important part of streams and rivers because in order for plants to grow, there has to be sunlight.

If there is a dry season, or if there is a season with little light, this will change how plants grow.

Animals in the Streams and Rivers

Most of the animals found in the streams and rivers are crabs, snails, fish, beavers, otters, crocodiles, snakes, and salmon.

The plants depend on the area, but some include river birch and willow trees.

Lakes and Ponds

Lakes and ponds are sometimes called lentic because they have waters that standstill.

There are four different types of lake zones, littoral zone, limnetic zone, euphotic zone, and benthic zone.

The littoral zone is the area that is close to the shore and this is where the plants grow.

The limnetic zone is the water that is not close to the shore.

The euphotic zone is the layer of water right below the surface. There is still enough sunlight to reach this area.

The benthic zone is the bottom of the lake or pond.

The temperature of Lakes and Ponds

The temperature of lakes and ponds changes depending on the weather.

The deeper that a person goes into the water, the cooler the water will be because of the lack of sunshine to warm it.

Animals of the Lakes and Ponds

Most animals that are found in lakes or ponds are fish, frogs, turtles, insects, worms, and more.

Plants include cattails, stone, and bladderwort and water lilies.

Facts About Freshwater Ecosystems:

  • The size of an area of water can determine what animals live there.
  • Smaller areas of water are warmer.
  • Plants can grow on the banks of water so that they have a nutrient source.
  • Animals use the waters to keep cool and to get food.
  • Waters get cooler in cooler weather and warmer in the warmer weather.

What Did You Learn?

  • What types of water areas have water that stands still? Lakes and ponds are called lentic because they have water that is sometimes not moving.
  • What kind of animals are found in ponds? Animals found in ponds are fish, frogs, turtles, and more.
  • Do plants grow close to water? Plants can grow close to water because they can use the water as a source of nutrients.
  • What determines if the water is a stream or a lake? The four things that determine if a waterway is a stream or a lake are temperature, light, flow, and chemistry.
  • What helps to keep water in ponds, lakes, rivers, and streams? Rain and melting snow help to keep water in ponds, lakes, rivers, and streams.