Freshwater Ecosystem – An Overview
Most of the Earth Surface (around 70%) is covered with water, but not all the water is freshwater. Only 3.5% is freshwater, and the rest 96.5% is saltwater in the form of oceans.
The Freshwater is found in the form of ponds, lakes, streams, frozen water, etc. other than oceans and seas. The freshwater ecosystem plays an important role in biodiversity. However, it is less extensive as compared to the saltwater ecosystem.
It supports various species of plants and animals. These species usually will not be able to survive in the saltwater ecosystem because their body is adapted to low-salt content, unlike saltwater species, which are adapted to high-salt content.
Freshwater bodies are one of the primary sources of water supply for our daily uses; This ecosystem is known for “lower salt content water bodies” generally less than 1%.
Follow this article to know more about characteristics and types of freshwater ecosystem and animals that belong to it.
Freshwater Ecosystem Definition
An ecosystem characterized by low-salt content, making a suitable environment for various plants and animals is known as a freshwater ecosystem. Freshwater resources vary in terms of size from very small to large.
Freshwater resources also differ from each other in terms of their movement. Some freshwater bodies are moving continuously like rivers, whereas some others are stagnant like ponds.
Table of Contents
- 1 Types of Freshwater Ecosystem
- 2 Freshwater Ecosystem Characteristics
- 3 Freshwater Ecosystem Animals
Types of Freshwater Ecosystem
The freshwater ecosystem is mainly divided into three types based on its region – Lotic, lentic, and wetland freshwater ecosystem.
Lotic Freshwater Ecosystem
In simple terms, the water bodies moving in one direction is known as a lotic freshwater ecosystem. Rivers and streams are common examples of lotic ecosystems.
There are many rivers and stream that flows from their origin and ultimately meets with other water channels or oceans at its mouth. Lotic freshwater travel through different locations from its source to mouth.
The lotic freshwater ecosystem is divided into three zones such as –
The source zone commonly known as the headwaters zone refers to the narrow and fast-moving zone of a lotic freshwater. The temperature is very cold in the source zone.
It contains much amount of dissolve oxygen but is not very productive like a transition zone. However, some freshwater fishes are found in source zone such as trout.
The transition zone is the middle part of the stream or river, where it becomes deeper and flows gently. The temperature of the transition zone is a little warmer, and it also contains less oxygen as compared to the source zone.
This is the productive zone of a lotic ecosystem with more nutrients where you can found various species of aquatic plants and algae.
The floodplain zone is also known as the mouth of a stream or river; This zone of a lotic ecosystem is characterized by a very low dissolved oxygen level, warm temperature, and with the slower flow.
In this zone, the water becomes murky due to sediments picked up all way in its journey from its source.
The Floodplain zone is quite poor in terms of diversity of flora and fauna. However, you can found some fishes in this zone that require less oxygen to survive like catfish & carp.
Lentic Freshwater Ecosystem
An aquatic ecosystem within stagnant or still water like ponds and lakes is known as Lentic Freshwater Ecosystem. Lentic ecosystem found in various sizes ranging from a few square meters to thousands of square km.
Some ponds last just for a few months as these are seasonal like sessile pools. On the other hand, lakes may exist for many years. Lentic ecosystem, i.e. Ponds and lakes, support a very limited number of species.
We can further divide the lentic ecosystem into three zones based on their depth and distance from the shoreline.
This is the topmost zone in the area near the shoreline of a pond or lake. The Littoral zone is characterized by a shallow and warm zone of a lentic ecosystem.
This zone provides shelter to various species of algae, few species of aquatic plants, clams, crustaceans, amphibians, snails, and various insects, etc.
Flora and fauna found in the littoral zone generally serve as food for other creatures like ducks, turtles, etc.
Limnetic Zone or Photic Zone
The open water zone where sunlight supports the photosynthesis process is known as the photic zone. The photic zone is also termed as a limnetic zone.
It is the zone of a lentic ecosystem that is generally dominated by planktons (both phytoplankton and zooplankton). As planktons are the primary producers, hence the limnetic zone plays an essential role in the food chain of a freshwater ecosystem.
Profundal Zone or Aphotic Zone
The deepwater zone where sunlight hardly penetrates is known as a profundal or aphotic zone. Photosynthesis is not possible in this zone due to the scarcity of sunlight. The aphotic zone is cold as compared to the other two zones.
The aquatic animals found in the profundal zone are heterotrophs in nature as they consume dead organisms.
Wetland Freshwater Ecosystem
Wetlands are still water bodies that support vascular plants. Marshes, swamps, and bogs are commonly known as wetland ecosystems. Wetlands are quite productive due to the proximity of water and soil.
The plant species found in the wetlands are known as hydrophytes as they have adapted the moist and humid environment of the region. The common hydrophyte plants found in the wetland ecosystem include cattails, tamarack, pond lilies, sedges, black spruce, etc.
As far as animal species are a concern, wetlands provide shelter to various amphibians, reptiles, birds, shrimp, shellfish, etc.
Freshwater Ecosystem Characteristics
- The freshwater ecosystem is a habitat for various plant and animal species. One of the major reasons is that it is quite rich in terms of nutrition and minerals.
- The freshwater ecosystem is less saline, unlike the marine ecosystem.
- The temperature in this ecosystem varies depending on some factors like location, season, and depth from the water surface.
- During summers, the temperature of the freshwater ecosystem generally ranges from 30-71 degrees Fahrenheit. Whereas during winters, the temperature ranges from 35-45 degrees Fahrenheit.
- The size and shape of freshwater ecosystems vary depending on location, an area covered, and depth of water bodies.
- The freshwater ecosystem contains sediments at the bottom. In gentle flowing freshwater bodies or still water bodies, the sediments remain in place.
- The freshwater ecosystem provides a suitable environment for various species of flora and fauna.
Freshwater Ecosystem Animals
The freshwater ecosystem provides a perfect environment for various animal species. Some animals of freshwater prefer moving water bodies like rivers, whereas some others prefer to live in stagnant water like ponds, lakes, wetlands, etc.
Fishes are the most common species of the freshwater ecosystem. Some fishes like salmon, trout, etc. prefer to live in moving clean water with a high level of oxygen. On the other hand, small muddy ponds provide an ideal environment for fishes like catfish, carp, etc.
Some freshwater fishes like pike and sturgeon require a large area to live as they grow large. Big lakes are a perfect place for these fishes.
Mammals, amphibians, and Reptile
Various species of mammals are also living in a freshwater ecosystem such as beavers, otters, etc. Most of the mammals live in small water bodies like lakes. This type of ecosystem is preferable for these mammals because they come to shores to reproduce, feed and breathe.
Some animals come to water streams and rivers to feed like bears, whereas some other animals like muskrat spend their whole lifespan in ponds.
Amphibians like frogs, salamanders belong to wetlands. The freshwater ecosystem is also a home for some species of reptiles like an alligator, turtle, snakes, etc. These reptiles live in a stagnant freshwater ecosystem.
Some birds are also a part of the freshwater ecosystem. Ducks, geese, etc. are commonly found in lakes, rivers, etc. On the other hand, some birds such as swallows belong to swamps and ponds. The birds like swallows are insect-eating, and swamps are an ideal shelter for these birds. It provides a good source of food.
This ecosystem is also a home for various species of insects such as mosquitoes, dragonflies, bees, wasps, water spiders, etc.
Freshwater ecosystem not only thrive a wide range of plant and animal species but also plays a vital role in our everyday life. Freshwater is the main source of water for us to fulfill our need for water to perform numerous tasks.
Some environmental issues like pollution are affecting the freshwater ecosystem very severely. The unlimited release of pollutants through various means are also polluting freshwater. We need to limit the emissions by doing few efforts to save freshwater sources and the species that depend on this ecosystem.