Freshwater Ecosystem


The freshwater habitats cover a very small portion of the earth’s surface compared with marine and terrestrial habitats but their significance is far greater than their area.

For humans, they are the most convenient and cheapest source of water for domestic, agricultural and industrial needs. Freshwater components are ‘bottle-neck’ in the water cycle.

The study of various aspects of freshwater ecosystems such as their physical or chemical composition, biological characteristics and organisms living in them is called Limnology.

Freshwaters are generally categorized into lentic/ still water and lotic or running or flowing water. The lentic includes ponds, swamps, marshes, etc. The lotic follows a gradient from springs to mountains then streams and rivers.

Freshwater and Freshwater Ecosystem

Freshwater is specified as having a low salt concentration– typically less than 1%. Freshwater describes the water found in lakes, ponds, streams, and any other body of water other than the sea. It supports a series of plant and animal communities whose structure is formed by the availability of food, oxygen (O), temperature level, and sunlight. Freshwater ecosystems include lakes, ponds, rivers, and streams.

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Ponds and lakes

These regions range in size from just a few square meters to thousands of square kilometers. Scattered throughout the earth, several are remnants from the Pleistocene glaciation. Lots of ponds are seasonal, lasting simply a number of months (such as sessile pools) while lakes may exist for centuries or more.

Ponds and lakes may have limited species variety considering that they are frequently separated from one another and from other water sources like rivers and oceans.


Streams and rivers

These are bodies of flowing water moving in one direction. Streams and rivers can be found all over– they get their starts at headwaters, which may be springs, snowmelt, and even lakes, and after that take a trip all the way to their mouths, typically another water channel or the ocean. The attributes of a river or stream changes throughout the journey from the source to the mouth.

The temperature is cooler at the source than it is at the mouth. The water is also clearer, has higher oxygen levels, and freshwater fish such as trout and heterotrophs can be found there. Towards the middle part of the stream/river, the width increases, as does species variety– various water green plants and algae can be found.

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Towards the mouth of the river/stream, the water ends up being murky from all the sediments that it has gotten upstream, reducing the quantity of light that can penetrate through the water. Given that there is less light, there is less variety of plants, and because of the lower oxygen levels, fish that need less oxygen, such as catfish and carp, can be present.



Wetlands are areas of standing or stagnant water that support marine plants. Marshes, swamps, and bogs are all considered wetlands. Plant species adapted to the really damp and humid conditions are called hydrophytes. These consist of pond lilies, cattails, sedges, tamarack, and black spruce. Marsh plants likewise consist of such species as cypress and gum. Wetlands have the highest species variety of all ecosystems.


Plant life in Freshwater Ecosystem

Plants and algae are essential to freshwater biomes due to the fact that they offer oxygen through photosynthesis and food for animals in this biome. Cattails and reeds grow along the shoreline of numerous freshwater ecosystems. In fast-moving streams and rivers, many plants have special structures that keep them from being carried away by the water.

Some aquatic plants have strong roots that keep them anchored securely, while others have stems that bend quickly with the movement of the water. Specific mosses are able to hold on to rocks.

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Animal life in Freshwater Ecosystem

Lots of animals reside in freshwater ecosystems. Some need the movement of the stream or river water to make it through. In fast-moving waters, animals that have to hold onto rocks and the bottom might have suction-cup like structures on their bodies. Others grow in still water environments, like lakes. There is a range of fish, birds, insects, amphibians, and shellfishes that make freshwater biomes their home. Trout live in both streams and rivers.

Some Famous Freshwater Ecosystems

The biggest freshwater habitat on the planet is the Everglades, a 1.5 million-acre wetlands in southern Florida. The Amazon River in South America starts in the Andes Mountains and goes 4,000 miles (6,400 km) to the Atlantic Ocean; it flows through 6 countries, consisting of Peru and Ecuador.

Lake Baikal in Siberia, an area in Russia, is the world’s greatest lake. This North Asian body of water consists of one-fifth of all the fresh water in the world.