Freshwater habitats include both still and moving water. Living things within rivers and streams can travel through the water to different areas. Many underwater inhabitants of ponds and Lakes, however, cannot escape from what may be quite a small area of water. However, even a tiny pool may have a complete, self-contained ecosystem. As well as plants and fish, freshwater ecosystems support living things that visit the water but spend part of their lives on land, such as amphibians, birds and insects. Many mammals also spend time in and around the water. Finally, the kinds of wildlife found in freshwater ecosystems will be affected by the climate and landscape around it. For example, the crocodile may be the fiercest predator in an African river, but its place may be taken by an otter in a European stream.
Cast out your fishing line or scoop your net through the water. You are bound to catch something when you are along the river’s edge or at the lake. Catching fish is always exciting, but while you wait for that fish to come along.
Freshwater ecosystems include lakes, ponds, rivers, streams, springs, and wetlands. You will find them in many different sizes, from very small to very large. The water within the ecosystem can be still (not moving), like in a pond, or it can be running (moving), like a river or stream.
Freshwater ecosystems are broken into three zones: littoral, open water and deep water – we’ll talk more about these below. The plants and animals within the ecosystem interact with light, food, oxygen, weather, and climate in different ways.
Plants and animals grow in different zones in freshwater ecosystems. The littoral (or marsh) zone refers to the plants and animals that grow closest to the edge of the water. The plants in this area can make great hiding spots for animals to hide from predators. You might find snails, clams, or even eggs and larvae from reptiles and insects in this area. Common predators (animals who prey, or feed, on other animals) in this zone include snakes, ducks and swans.
The open water zone refers to plants and animals that live near the top of the water. Some float on top of the water and have tiny roots that go down into the water, like duckweed. Others have their roots down in the mud at the bottom of the pond and leaves that float at the top of the pond, like water lilies. These plants get lots of sunlight, which makes them the top energy producers for the animals in the water. Many fish also swim in this open water zone.
Freshwater ecosystems play a fundamental ecological role and provide economically important products and services. They provide critical habitats for a large number of aquatic plants, fishes, reptiles, birds and mammals. They host many migratory and threatened species of birds, reptiles and fish. The freshwater ecosystems are areas of tourist attraction by providing recreation sites for game and bird watching.
Freshwater ecosystems, especially vegetated wetlands, play an important role in mitigation against climate variability. They do so through a number of ecosystem functions including flood control, water purification, shoreline stabilization and sequestration of carbon dioxide. At landscape level, wetlands control soil erosion and retain sediments and in so doing concentrate nutrients in the wetland soil. They also provide economic benefits such as fresh water, fisheries, fuel-wood, building material, medicinal products, honey and foliage for livestock and wildlife. Wetlands provide fertile land for agricultural, mineral salts, sand and soil for making pottery and building bricks. Wetlands are central to rural subsistence economies and livelihood activities of many rural communities in Kenya. Freshwater ecosystems in general are critical to poverty alleviation and creation of employment and wealth.