Aquatic Ecosystem - Types, Function & Defination

What is an Aquatic Ecosystem?

An aquatic habitat can be described as a complex community of living organisms, that include both plants, animals, and microorganisms, interacting both between themselves and with their physical environment, within a water body. These ecosystems are important in terms of maintaining global biodiversity and support an enormous variety of species that depend on aquatic environments for survival.

Types of Aquatic Ecosystems

Aquatic ecosystems may be classified into the following broad categories based on their characteristics:

Freshwater Ecosystems: All freshwater lakes, rivers, streams, and wetlands fall under this category. Freshwater ecosystems are home to a rich variety of species, which makes them an essential source of water for drinking and irrigation purposes.

Marine Ecosystem: This portion of the Earth's surface is taken up by marine ecosystems. It is mainly composed of oceans, coral reefs, and estuaries. They are very rich in terms of species diversity and also play a critical role in regulating weather.

Lentic Ecosystem: These are ecosystems that result from still or standing bodies of water, such as lakes and ponds. They show distinct zones, such as the littoral, limnetic, and benthic zones, hosting different species adapted to their respective environments.

Lotic Ecosystem: In contrast, lotic ecosystems refer to flowing water bodies, such as rivers and streams. The dynamics of an ecosystem are characterized by changing parameters, thus hosting species adapted to the current conditions of the flow.

Examples of Aquatic Ecosystems

There are many examples of aquatic ecosystems, which depict their diversity:

Ponds and Lakes: Freshwater ecosystems harbour different organisms, from fish and amphibians to aquatic plants.

Rivers: Lotic ecosystems often support species such as salmon and various aquatic invertebrates.

Coral Reefs: The marine ecosystems are mostly well known for biodiversity, housing numerous species of fish and other marine creatures.

Wetlands: Transitional areas between land and water, with unique communities of plants and animals.

Importance of Aquatic Ecosystem

Aquatic environments play a critical role for several reasons:

Biodiversity: They support an incredibly wide variety of species, which add to global biodiversity.

Ecosystem Services: The key areas of importance of aquatic ecosystems are the filtration of water, regulatory functions of the climate system, and nutrient cycling.

Human Use: Many communities find food, recreation, and economic sources in aquatic ecosystems, such as commercial fisheries and tourism.

Aquaculture: Aquatic ecosystems support fish farming and aquaculture, which enhance food production and livelihood.

Hydroponics: Freshwater systems are vital for hydroponic farming, where plants are grown in water solutions without soil.

Controls Pollution: Wetlands and aquatic plants act as natural filters, cleaning pollutants from water.

Zones of Aquatic Ecosystem

Aquatic ecosystems, especially lakes and oceans, are divided into distinct zones based on depth, light penetration, and distance from the shore. Each zone has its own physical conditions and organisms.

1. Littoral Zone

• Shallow water near the shore.

• Well-lit, nutrient-rich, supports rooted plants, algae, and diverse fauna like snails, insects, and amphibians.

• Most productive zone in freshwater bodies.

2. Limnetic Zone

• Open water area away from the shore but still within the depth of light penetration.

• Dominated by plankton, small fish, and zooplankton.

• Primary site for photosynthesis in lakes and ponds.

3. Benthic Zone

• The bottom surface of water bodies (lake/ocean floor).

• Occupied by decomposers, detritivores, and benthic organisms like mollusks, worms, and some fish.

• Plays a key role in nutrient recycling.

Tips & Tricks for Exams

Here are some tips and tricks to prepare Aquatic Ecosystems for exams:

Learning Aids: Get to know the various diagrams and characteristics of aquatic ecosystems such as freshwater (lentic and lotic) and marine ecosystems. Take special notice of the different types of flora and fauna adapted for each environment. For example, there's the phytoplankton in freshwater, and in the marine setting, numerous species of coral thrive.

Mnemonics: Learn mnemonics for key features of aquatic ecosystems. One example is "FLAME" to remember Freshwater, Lentic, Aquatic, Marine, and Ecosystem.

Practice Diagrams: Draw neat labelled diagrams illustrating the different zones of aquatic ecosystems, namely the littoral, limnetic and benthic zones. Such practice usually helps in memorizing the topic, and examination questions usually require such diagrams.

Real-Life Examples: By applying theoretical concepts to real-life examples, you can learn about specific types of ecosystems. For example, both the study of the Amazon River, which is lotic, and the Great Barrier Reef, which is marine, will help reinforce your learning and add real-life context to the material.

Weightage in Exams

The table below indicates the weightage and types of questions typically asked about aquatic ecosystems in various exams:

Aquatic Ecosystem NEET MCQs

Q1. Whole ecosystem is too much big and complex to be studied at one time, it is convenient to divide it into two basic categories named as :

1. Inland and outland ecosystem

2. Complex and non-complex ecosystem

3. Estuary and forest ecosystem

4. Terrestrial and aquatic ecosystem

Correct answer: 4) Terrestrial and aquatic ecosystem

Explanation:

Terrestrial and the Aquatic Ecosystem -

Since the whole ecosystem is too big and complex to be studied at one time, it is convenient to divide it into two basic categories, namely the terrestrial and the aquatic.

- wherein

Forest, grassland and deserts are some examples of terrestrial ecosystems; ponds, lakes, wetlands, and rivers and estuaries are some examples of aquatic ecosystems.

Hence the correct answer is Option (4) Terrestrial and aquatic ecosystem.

Q2. Which of the following best describes an ecosystem?

1. A single organism

2. A group of organisms of the same species

3. A group of organisms of different species interacting with each other and their physical environment

4. A group of different species interacting with each other but not their physical environment

Correct answer: 3) A group of organisms of different species interacting with each other and their physical environment

Explanation:

A group of organisms of different species interacting with each other and their physical environment best describes an ecosystem. An ecosystem is a community of living organisms, along with their nonliving physical and chemical environment, that interact and function as a unit. The interactions between organisms and their environment are essential for maintaining the balance and sustainability of the ecosystem.

Hence, the correct answer is Option (3) A group of organisms of different species interacting with each other and their physical environment.

Q3. Which of the following is an example of an ecosystem?

1. A single tree

2. A group of ants

3. A coral reef

4. A single cell

Correct answer: 3) A coral reef

Explanation:

An ecosystem is a community of living and nonliving things interacting with each other in a specific environment. A coral reef is an excellent example of an ecosystem as it is a complex community of marine organisms interacting with each other and their physical environment. The reef provides a habitat for various organisms, including fish, invertebrates, and algae. The coral is a living organism that interacts with the other microorganisms and physical components of the ecosystem to create a thriving community.

Hence, the correct answer is option 3) A coral reef.

Also Read:

• MCQ on Ecosystem and its Components

• Energy Flow in Ecosystem

• Biodiversity and Conservation

FAQs on Aquatic Ecosystem

Define an aquatic ecosystem.

An aquatic ecosystem is an ecosystem found in a body of water, where living organisms interact with the physical and chemical environment of water. It includes both freshwater and marine systems. Aquatic ecosystems support a wide variety of organisms such as plankton, fish, amphibians, aquatic plants, and microorganisms. They play a crucial role in maintaining biodiversity and regulating Earth’s climate and nutrient cycles.

What are the types of aquatic ecosystems?

Aquatic ecosystems are broadly divided into two types:

• Freshwater ecosystems – These include lentic (still water like lakes, ponds, swamps) and lotic (flowing water like rivers, streams) systems.

• Marine ecosystems – These cover oceans, seas, estuaries, coral reefs, and coastal areas. Marine ecosystems are more saline, vast, and diverse, supporting organisms from phytoplankton to whales.

What is the difference between lentic and lotic ecosystems?

Lentic ecosystems are still water bodies like ponds, lakes, and wetlands where water does not flow significantly. They usually support higher sedimentation and diverse plant life. Lotic ecosystems, on the other hand, are flowing water bodies like rivers and streams, where water movement is continuous and rapid. Lotic systems have higher oxygen content but fewer rooted plants compared to lentic systems. Thus, the key difference lies in water movement and ecological characteristics.

Why are aquatic ecosystems important?

Aquatic ecosystems are vital for life on Earth. They provide habitats and food for a wide variety of organisms, regulate the water cycle, and help in nutrient recycling. Oceans act as major carbon sinks, helping regulate global climate. Freshwater ecosystems provide drinking water, irrigation, and fisheries. Aquatic systems also support human livelihood, transportation, recreation, and maintain biodiversity essential for ecological balance.

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