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Aquatic Ecosystem is defined as a water-based habitat of an ecosystem in which all living species interact with the environment's physical and chemical properties. The aquatic ecosystem plays a significant role in striking a balance between the atmosphere, lithosphere, and biosphere. Oceans, lakes, and rivers are examples of aquatic ecosystems. Also, environmental habitat is an essential component of such an ecosystem. Water plays a major role in the lives of many living organisms that rely on water to support their food, shelter, reproduction, and a variety of other life functions.
Read More: Tundra Ecosystem
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Key Terms: Ecosystem, Aquatic, Freshwater Ecosystem, Lotic, Lentic, Wetlands, Marine Ecosystem, Ocean Ecosystem, Coastal Ecosystem, Estuaries, Coral Reefs
Definition of Aquatic Ecosystem
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- The aquatic ecosystem is the basic functional unit facilitating the sustenance of aquatic organisms.
- The unique physicochemical features of this ecosystem allow the material transfer, carrying out significant chemical reactions, and other key functions needed for the survival of the life forms.
- Nekton, plankton, and benthos are some of the most prevalent aquatic creatures.
- Lakes, oceans, ponds, rivers, swamps, coral reefs, wetlands, and popular examples of freshwater aquatic ecosystems.
- While marine habitats include oceans, intertidal zones, reefs, and the seabed.
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Types of Aquatic Ecosystem
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The different types of ecosystems are as follows:
Freshwater Ecosystem
- Freshwater ecosystems only cover about 1 percent of the earth's surface.
- Lakes, ponds, rivers and streams, marshes, swamps, bogs, and ephemeral pools are all examples of freshwater.
- Freshwater ecosystems are divided into three types: lotic, lentic, wetlands, and swamps.
Lentic habitats are bodies of standing water such as lakes, ponds, pools, bogs, and other reservoirs. Flowing water bodies such as rivers and streams are represented by lotic ecosystems. Let us look at these in detail.
Lotic Ecosystems
- Lotic ecosystems primarily refer to unidirectionally flowing, quickly flowing waterways such as rivers and streams.
- Several insect species, such as beetles, mayflies and stoneflies, as well as several fish species, such as trout, eel, and minnow, live in these settings.
- These ecosystems also include mammals such as beavers, river dolphins, and otters, in addition to aquatic species.
Lentic Ecosystems
- They encompass all ecosystems with standing water.
- The principal examples of the Lentic Ecosystem are lakes and ponds.
- The term lentic is used to describe water that is stationary or relatively still.
- Algae, crabs, shrimps, amphibians like frogs and salamanders, rooted and floating-leaved plants and reptiles like alligators and other water snakes can all be found in these habitats.
Wetlands and Swamps
- A swamp is an area in the forest that is permanently filled with water.
- If there is no forest around, then it is termed as a wetland.
- The water in wetlands and swamps can be freshwater, brackish water or seawater.
- Freshwater swamps are mostly found inland while seawater swamps are found along the coastal areas.
- Water levels of swamps often face fluctuations due to rain and flood.
- Many terrestrial, aquatic and amphibians such as crocodiles, alligators, turtles, fish and migratory birds inhabit swamps and wetlands.
- Due to excessive urbanisation, swamps and wetlands are facing environmental degradation.
Marine Ecosystem
- The marine environment spans the majority of the earth's surface area.
- Oceans, seas, the intertidal zone, reefs, the seabed, estuaries, hydrothermal vents, and rock pools make up two-thirds of the earth's surface.
- Aquatic animals cannot exist outside of water.
- Salt concentrations are higher in the marine habitat, making it difficult for freshwater creatures to survive.
- In addition, marine species are unable to survive in freshwater.
- Their bodies are designed to survive in saltwater and will swell if placed in less salty water (osmosis).
- They can be further classified as ocean ecosystems, estuaries, coral reefs, and coastal ecosystems.
Ocean Ecosystems
- The Pacific, Indian, Arctic, and Atlantic Oceans are the five primary oceans on earth.
- The Pacific and Atlantic Oceans are the largest and deepest of these five oceans.
- More than five lakh aquatic species call these oceans home.
- Shellfish, sharks, tube worms, crabs, turtles, crustaceans, blue whales, reptiles, marine mammals, seagulls, plankton, corals, and other ocean plants are just a few of the organisms that live in these environments.
Estuaries
- Estuaries are critical forms of natural habitats which are typically formed where the sea and the rivers meet.
- The transition from land to sea happens in this region.
- As a result, the water here is more saline in comparison to freshwater ecosystems but more dilute than the marine ecosystems.
- Estuaries have much economic importance as they are capable of trapping plant nutrients and generating quality organic matter in comparison to all other land-based ecosystems.
- Estuaries today have also become hot spots for recreational activities and scientific studies.
- Some examples are tidal marshes, coastal bays, and river mouths.
Coral Reefs
- Coral reefs are underwater structures built from the skeletons of marine vertebrates, also called corals.
- These are found in most of the world’s oceans.
- These corals form reefs called hermatypic or hard reefs as they give out hard calcium carbonate exoskeletons that protect their structure and support important life functions. Sea anemones are classic examples of hard coral reefs. The other species form soft reefs that are comparatively flexible organisms like plants and trees. Sea fans and sea whips are some of the most found varieties of soft reefs.
- The environmental conditions needed for the survival of coral reefs are warm, shallow, clear, and moving waters with ample sunlight.
- The Great Barrier Reef in Australia is the world’s largest coral reef with a length of approximately 1500 miles.
Coastal Systems
- Coastal ecosystems are made up of open systems of land and water that are linked together.
- The structure and diversity of marine habitats differ.
- The bottom of the coastal ecosystem is home to a diverse range of aquatic plants and algae species.
- Crabs, fish, insects, lobsters, snails, shrimp, and other animals make up the fauna.
- The majority of aquatic species are streamlined, which helps them save energy by reducing friction.
- The locomotors and respiratory organs are the fins and gills, respectively.
- Freshwater species have special adaptations that help them to drain excess water from their bodies.
- Aquatic plants have a variety of roots that aid in their survival in water.
- Some plants, such as water hyacinths, have submerged roots, whereas others have emergent roots or are floating.
Features of Aquatic Ecosystem
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The prominent features of aquatic ecosystems are:
- Water Diversity: They can be made of either freshwater or saltwater.
- Varied Habitat Population: They provide habitat for a variety of flora and fauna ranging from shallow water to even the deepest of oceans.
- Exclusive Biodiversity: Algae and corals make up the majority of the flora of aquatic ecosystems.
- Rich Sustainance Network: They facilitate the smooth continuity of the overall complex food chain play, regulate the hydrological cycle, and act as a pollution filter.
Aquatic Ecosystem PDF
Functions of Aquatic Ecosystem
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These points emphasize the significance of the aquatic ecology:
- Allows nutrients to be recycled more easily.
- Aids in the purification of water
- Recharges the groundwater table
- Provides a home for aquatic vegetation and fauna.
- Prevents flooding
Read More:
| Important Chapter Topics | ||
|---|---|---|
| Pelagic Zone | Benthic Zone | Productivity in Ecosystem |
| Biome Vs Ecosystem | Food Chains and Webs | Decomposers |
| Microbes in Human Welfare | Diversity in Living Organisms | Biomes |
Things to Remember
- Aquatic ecosystems are fundamental for the development and growth of all water-based organisms.
- Evolution in marine ecosystems has facilitated organisms to survive in saltwater and adapt their body structure based on the aquatic water type.
- Aquatic ecosystems are categorized as freshwater and marine water ecosystems.
- The freshwater ecosystem can be classified as lotic, lentic, and swamps or wetlands.
- The marine ecosystems are broadly classified as ocean ecosystems, estuaries, coral reefs, and coastal ecosystems.
- Several important features of the aquatic ecosystem make it home to a wide variety of flora and fauna.
- The Aquatic ecosystem replenishes nutrients, aids water purification, and recharges the groundwater table.
Read More: Endangered Species
Previous Year Questions
- Which of the following aquatic plant does not show pollination by water? … (KCET 2021)
- Aquatic reptiles are … (NEET 1999)
- Upper part of sea/aquatic ecosystem contains … (NEET 1988)
- An ecosystem which can be easily damaged but can recover … (NEET 2004)
- Energy transfer from one trophic level to other...[NEET 1999]
- the rate of production of organic matter by consumers….[NEET 2012]
- About 70% of total global carbon is found in...[NEET 2008]
- An ecosystem which can be easily damaged but can….[NEET 2004]
- The biomass available for consumption by the herbivores...[NEET 2010]
- Both hydrarch and xerarch successions lead to...[NEET 2011]
- During ecological succession...[NEET 2015]
- In a biotic community, the primary consumers are...[NEET 1995]
- In an ecosystem, which one shows one-way passage...[NEET 1988]
- Upper part of sea/aquatic ecosystem contains...[NEET 1988]
- Vertical distribution of different species occupying different...[NEET 2015]
- What is true of ecosystem?...[NEET 1988]
- Which ecosystem has the maximum biomass ?...[NEET 2017]
Sample Questions
Ques 1. What is an aquatic ecosystem? (1 Mark)
Ans. The aquatic ecosystem is a water-based habitat in which living creatures coexist with one another and with their surroundings to thrive. The three primary kinds of organisms found in aquatic habitats are planktons, nektons, and benthos.
Ques 2. What are the types of ecosystems? (3 Mark)
Ans. The aquatic ecosystem is classified as follows:
- Freshwater
- Marine
Freshwater ecosystems are further classified as:
- Lentic
- Lotic
- Wetlands/ swamps
Marine ecosystems are further classified as:
- Oceans
- Estuaries
- Coral Reefs
- Coastal
Ques 3. What are the important characteristics of an Aquatic Ecosystem? (1 Mark)
Ans. Abiotic and biotic components make up the prominent characteristics of aquatic habitats. Depth, nutrition, temperature, salinity, flow, and temperature are the abiotic parameters. The living creatures of the ecosystem are the biotic factors.
Ques 4. List two of the aquatic ecosystem's functions. (1 Mark)
Ans. These are two of the functions of the aquatic ecosystem, as well as its types.
- It aids in the recycling of nutrients and the purification of water.
- It aids in the replenishment of groundwater levels.
Ques 5. Why can't creatures from the marine aquatic habitat live in freshwater? (1 Mark)
Ans. The majority of animals in the marine aquatic ecosystem have evolved to exist in saltwater. As a result, if they are in less salty water, such as freshwater in rivers, the osmosis process causes their bodies to swell.
Ques 6. What is the ecosystem's significance? (2 Marks)
Ans. The ecosystem keeps the environment in check. It provides clean air to breathe and helps to regulate the climate by sequestering carbon. It circulates nutrients through multiple biogeochemical cycles, ensuring that we have clean drinking water without the use of expensive techniques. A variety of living organisms rely on it for sustenance and shelter. It also supplies raw materials for a variety of industrial and home applications.
Ques 7. Which ecosystem would be more productive in terms of primary productivity?
An old forest in its natural state, a young forest, an alpine meadow, and a tiny contaminated lake. (2 Marks)
Ans. A more productive environment is one that has more producers. Young forests are more productive in terms of primary productivity than older and mature forests because they grow faster. Because there are fewer producers and more dead stuff in alpine meadows and shallow contaminated lakes, they will be less productive.
Ques 8. Explain how energy flow in an ecosystem supports the second rule of thermodynamics. (3 Marks)
Ans. According to the second law of thermodynamics, all activity involving transformation results in the loss of energy in the form of heat and an increase in disorder, with the exception of deep hydrothermal ecosystems. Only 2-10% of total PAR (Photosynthetically Active Radiation) is absorbed by organisms that generate organic matter through photosynthesis.
Additionally, the energy is used in metabolic activities, the formation of food, and the storage of biomass (very little). According to Lindeman's law, biomass or trapped energy is transmitted to the next trophic level. Approximately 10% of the stored energy is transferred from one trophic level to the next.
Ques 9. What types of aquatic settings can you find? (3 Marks)
Ans. There are two types of aquatic settings that are capable of supporting life. There are two types of life zones: saltwater and freshwater. The salinity of the water determines the principal sorts of organisms found in aquatic habitats. The amount of salts dissolved in a volume of water is referred to as salinity. That is why freshwater and saltwater life zones are separated into aquatic life zones.
A coral reef is an example of a saltwater or marine life zone. A lake is an example of a watery living zone.
Ques 10. What species can be found in aquatic life zones, and how do they interact? (5 Marks)
Ans. Both saltwater and freshwater life zones are home to a diverse range of species that interact in a variety of food webs. A food web is a system in which certain organisms, either plant or animal, devour other organisms to establish a sustainable system in which species are in balance and overpopulation is avoided.
Free-floating, extremely small organisms known as plankton, strongly swimming species known as nekton, bottom-dwelling organisms known as benthos, and decomposers such as bacteria are the most common types of organisms found in aquatic ecosystems.
Because it is consumed, plankton is a type of organism that supports several species. Because phytoplankton is made up of producers, it is the most significant type of plankton. This simply implies that it creates materials, such as oxygen, that will maintain the lives of other aquatic organisms. Phytoplankton is the most commonly consumed type of plankton. The other plankton species are either consumers or half-producers (nanoplankton) (zooplankton).
Nekton is a type of bigger, swimming consumer that feeds on plankton or other consumers. Fish and turtles, for example, are nekton. Oysters and lobsters are examples of benthos or bottom-dwelling organisms.
In an aquatic ecology, decomposers have only one job: to break down (decompose) organic material. They break down dead plant and animal debris into nutritional compounds that producers can employ to create life-sustaining stuff.
Ques 11. What made organisms adapt aquatic ecosystem? (2 Marks)
Ans. According to scientists, Earth’s first cellular life arose primordial in oceans. Later as evolution takes place many animals from the aquatic ecosystem came to land and adopt themselves to live in the condition of the land.
Ques 12. Running water and stagnant water are found in which aquatic ecosystem? (2 Marks)
Ans. The freshwater ecosystems have running water as streams and rivers. Ponds, tanks and lakes are ecosystems where water doesn’t flow and is stagnant. So in freshwater ecosystem, we can find both running water as well as stagnant water.
Ques 13. Which ecosystem experiences drastic fluctuations in water level? (2 Marks)
Ans. Wetlands are special ecosystems in which the water level fluctuates dramatically in different seasons. They have expanses of shallow water with aquatic vegetation forming an ideal habitat for fish, water birds and aquatic plants.
Ques 14. Why is sea salty? (2 Marks)
Ans. Sea has a vast collection of many minerals. Apart from this, the rivers flowing from high mountains collect all nutrients and minerals along their way and deposit in the sea. This makes the sea salty.
Ques 15. Which is the largest ecosystem on earth? (2 Marks)
Ans. Ocean ecosystem is the largest ecosystem on earth. The earth is covered by 70% of water. This is why the earth appears to be blue in color when viewed from space.
Ques 16. Where can we find coral reefs? (2 Marks)
Ans. Coral reefs are found in marine ecosystems, especially in shallow tropical seas. The coral reefs are formed from the skeletal remains of primordial species. Coral reefs are entirely made up of calcium deposits and are home to many species of organisms.
Ques 17. Which is the world’s most productive ecosystem in terms of biomass production? (2 Marks)
Ans. Brackish water ecosystems in river deltas are covered by mangrove forests and are among the world’s most productive ecosystems in biomass production. Sunderbans in the delta of the Ganges river is one example.
Ques 18. Which is the simplest aquatic ecosystem? (2 Marks)
Ans. Pond is the simplest aquatic ecosystem. Most ponds become dry after the rain is over and are covered by terrestrial plants for the rest of the year. When the ponds is filled in the monsoon season, a large number of food chains are formed in the pond ecosystems.
Ques 19. Which ecosystem is known as a giant permanent pond? (2 Marks)
Ans. A lake ecosystem functions like a giant permanent pond. A large amount of its plant material is algae. Algae derive its energy directly from the sun, this energy is transferred to microscopic animals which feed on algae.
Ques 20. How many oceans constitute the marine ecosystems around peninsular India? (2 Marks)
Ans. The Indian peninsula is surrounded by 3 waters namely:
- The Indian Ocean in the south
- Bay of Bengal in the East
- The Arabian Sea in the West
Ques 21. Beach is classified into which ecosystem? (2 Marks)
Ans. Beach is classified into seashore ecosystem. Beaches can be sandy, rocky, shell covered. On each of these different types, several species have evolved to occupy a separate function. Many crustaceans such as crabs, turtles and birds like seagulls habitat this ecosystem.
Ques 22. How are humans dependent on aquatic ecosystem? (2 Marks)
Ans. Water is essential in all walks of life for all organisms. For humans, water is needed for drinking, cleaning, agriculture and many industrial processes. Water is the elixir of life without which life ceases to exist.
Ques 23. What is Zooplankton? (2 Marks)
Ans. Zooplankton is the second trophic level in a lake ecosystem. Small fish which feed on zooplankton come under the third trophic level.
Ques 24. What is a man-made ecosystem? (2 Marks)
Ans. Man-made ecosystems are those which are artificially built by man that mimics the natural ecosystems. Some examples of man-made ecosystems are dam ecosystem, agriculture ecosystem, garden ecosystem, etc.
Ques 25. What is tropical rainforest? (2 Marks)
Ans. Tropical rainforests are rainforests in tropical rainforests. They have no dry season and have an average precipitation of 60mm all round the year. These are also called lowland equatorial evergreen rainforests.
Ques 26. What is a mangrove forest? (2 Marks)
Ans. Mangrove forests are those which exist in the tropical and subtropical coastal regions. The trees in these forests are small and shrub-like. They grow in brackish or saline water.
Ques 27. Mention some examples of the Lotic ecosystem. (2 Marks)
Ans. Streams, rivers and springs are some examples of the Lotic ecosystem.
Ques 28. What is phytoplankton? (2 Marks)
Ans. Phytoplanktons form the first trophic level in a water ecosystem. These are microscopic vegetation that floats on the water surface and undergoes a photosynthesis process to produce their own food. Many small fish feed on phytoplankton.
Ques 29. Explain the basic outline of the food chain in an aquatic ecosystem. (2 Marks)
Ans. The basic outline of the food chain in an aquatic ecosystem is:
Phytoplankton → zooplankton → Small fish → Large fish
The phytoplankton is autotrophs which have the ability to prepare their own food by the process of photosynthesis.
Ques 30. What is Biosphere? (2 Marks)
Ans. The combined ecosystem of Atmosphere, Geosphere, Hydrosphere and Lithosphere is called Biosphere.
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