This includes all flowing inland bodies such as creeks, rivers, streams and so on. The ecology of flowing water is very unique in many ways and often shaped by the nature and behavior of the flowing water. A river, for example, is a constantly flowing water body, usually unidirectional, with a source and an end. It is usually in a constant physical change. At the source of the river, it is usually narrower in size, cold, fast-flowing and rich in oxygen. Down to the end, it is usually very wide in size, less oxygen, slow-moving and warmer in temperature. This means lifeforms in a lotic system is not the same, as it depends on the following:
1. The nature and behavior of flowing water
The chemical makeup such as oxygen, pH and alkalinity
The temperature of the water, depth of the water and how much sunlight can penetrate it and so on
The velocity of the water
The stage of the river in its course. Flowing water at its source tend to flow very fast, whiles water at its end tend to flow very slowly with a lot of nutrients and particle deposition
The topography of the land (slopes, highlands, and lowlands)
2. The adaptation of its living organisms
With the above picture of flowing water in mind, how are living organisms (plants and animals) adapted to survive in these flowing water bodies?
Organisms in these waters have suckers and hooks that help them stick to the water-bed, rocks or plants.
Some of them also have a streamlined body that help them swim against water currents.
Plants such as diatoms, moss, and sponges attach themselves firmly with the substratum.
3. The living structure along the flowing water
There are other plants and animals that do not live in the water but are a part of the ecosystem that exists in that flowing water. Small plants, insects, frogs, birds and other animals that feed off the plants from the flowing water, in turn, provide organic material for life forms in the water. The trees provide shelter for the birds and animals and also provide shade for slowing down evaporation. Some plants and their root systems also filter the water from pollutants.