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DEPARTMENT OF ENVIRONMENTAL SCIENCE,

PUB KAMRUP COLLEGE

ASSIGNMENT ON

ECOSYSTEM
TOPIC - Ecosystem concept and its components.
Description of a model ecosystem

Submitted by-
Debajit Sarma
GU Roll no: US-181-033-0054
GU Registration No: 18022424
BSc 4th Semester, Chemistry Department
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ECOSYSTEM
A complex relationship between all the living and nonliving things
(plants, animals, organisms, sun, water, climate etc) interact with each other
is known as ‘An Ecosystem’. Ecosystems are the foundation of ‘Biosphere’ and
maintain the natural balance of the earth.
For example, let’s take the relationship between sheep and lion in the
ecosystem; for its survival, the lion eats the sheep. And each relationship like
this has an effect on other creatures and plants living in the same area. Hence,
if the lion eats more sheep, it has an effect on the plants too; they begin to
flourish; since there aren’t many sheep to eat the plants.
Each organism in the ecosystem plays an important role, so anytime a
‘foreign’ factor is put in the ecosystem; it poses a major threat to the
ecosystem. This happens because the foreign factor can deform the natural
balance of the ecosystem and harm it potentially.
This foreign factor could be anything ranging from rising temperature
to the tsunami. Not just the foreign factor but man-made can also destroy the
ecosystem.
Ecosystems are created by the interrelationships between living
organisms and the physical environments they inhabit (land, water, air).
Ecosystems require a source of energy to make them work and for most,
although not all, this is light from the sun.
To study ecosystems we have to start to identify the components involved and
the interrelationships between them. We can list the living organisms by
identifying the species involved.

Components of the Ecosystem

The components of an ecosystem are divided into abiotic components, that
include all nonliving components such as minerals, climate, soil, water, sunlight
and biotic components that include all the living components. These components
together make up for the flow of energy in the ecosystem and the nutrient cycle
in the ecosystem.

The gleaming energy from the sun is the basic source of energy in all the
ecosystems. The autotrophs (self-sustaining organisms) absorb this energy and
produce photosynthesis where they can use this energy to convert CO2 and H2O
into simple carbohydrates. The autotrophs store energy in these carbohydrates,
which they then use to produce more complex and organic products like lipids,
proteins, and starches that help the organism to survive. These autotrophs are
the producers of the ecosystem.
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Organic compounds produced by autotrophs help in the survival of the

heterotrophic organisms. And heterotrophs are the consumers of the ecosystem
since they’re incapable of making their own food. All organisms like bacteria,
fungi or animals are heterotrophs.

An ecosystem consists of three types of ecosystems, another term for

which is ‘Biomes’. The three major types are:

a. Aquatic biomes

b. Terrestrial biomes

c. Lentic biomes

a. Aquatic Biomes:
Aquatic biomes are the ones, one finds in water bodies, such as oceans, rivers,
seas, lakes, springs, etc. This biome is further divided into smaller ecosystems:
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Pond Ecosystems:
Pond ecosystems are comparatively small and mostly include many kinds of
amphibians and insects. At times one can also find fishes here but they aren’t
capable of moving as easily as the amphibians.

River Ecosystems:
This ecosystem consists of fishes along with plants, amphibians, and insects. One
may also find birds that hunt in and around the water for its food (small fishes).

Shallow water Ecosystem:

Here one can only find tiny fishes and corals that live in shallow waters close to
land.

Deepwater Ecosystem:
These are kind of ecosystem where one can find gigantic sea creatures that live
at the deep bottom of the sea. Creatures that wouldn’t be visible to the normal
human eye.

b. Terrestrial Biomes:

Terrestrial ecosystems are ecosystems that are found on land that include forests,
deserts, grasslands, tundras, and coastal regions. There can be more than one
terrestrial biome depending on its climate. This ecosystem further divides into
Rainforests, Tundra, desert, forests.
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Rainforests:
Rainforests are the kind of ecosystems that are extremely dense because of a
variety of organisms living in a tiny area.

Tundra:
Tundra is the kind of ecosystem that is a relatively simple ecosystem since only a
few life forms can survive this ecosystem; especially because of its harsh
conditions.

Deserts:
They are opposite of tundras, yet they have extreme conditions. Animals prefer
to live in extreme heat than extreme cold.

Forests:
One can find more forests than any other ecosystem in the world such as
deciduous and coniferous forests. Forests can support many life forms and
complex ecosystems.

c. Lentic Biomes:
These are the kinds of ecosystems that support both aquatic and terrestrial life
forms such as swamps. The only requirement is that this kind of ecosystem is the
exposure for the photosynthesis process to happen; since organisms here survive
on the carbohydrates made by photosynthesis.
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A model ecosystem
An ecosystem is a dynamic complex of plant, animal, and
microorganism communities and the nonliving environment, interacting as a
functional unit. Remember that the organisms living in an ecosystem are
broken down into categories: producers, consumers, and decomposers.

For example we can take a pond as a model Ecosystem. A pond is a quiet

body of water that is too small for wave action and too shallow for major
temperature differences from top to bottom.

It usually has a muddy or silty bottom with aquatic plants around the
edges and throughout. However, it is often difficult to classify the differences
between a pond and a lake, since the two terms are artificial and the
ecosystems really exist on a continuum. Generally, in a pond, the temperature
changes with the air temperature and is relatively uniform. Lakes are similar
to ponds, but because they are larger, temperature layering or stratification
takes place in summer and winter, and these layers turnover in spring and
fall. Ponds get their energy from the sun. As with other ecosystems, plants are
the primary producers. The chlorophyll in aquatic plants captures energy
from the sun to convert carbon dioxide and water to organic compounds and
oxygen through the process of photosynthesis. Nitrogen and phosphorus are
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important nutrients for plants. The addition of these substances may increase
primary productivity. However, too many nutrients can cause algal blooms,
leading to eutrophication.

Producers

Phytoplanktons, literally “wandering plants,” are microscopic algae that float

in the open water and give it a green appearance. They carry out
photosynthesis using carbon dioxide that is dissolved in the water and release
oxygen that is used by the bacteria and animals in the pond. Phytoplankton
are not actually plants-they are protists!

• Periphytic algae are microscopic algae that attach themselves to substrates

and give the rocks and sticks a greenish brown slimy appearance. They also
carry out photosynthesis and produce oxygen, often near the bottom of the
pond where it can be used by decomposers.

• Submerged plants grow completely under water

• Floating plants include plants that float on the surface and plants that are
rooted on the bottom of the pond but have leaves and/or stem that float.

• Emergent plants are rooted in shallow water but their stems and leaves are
above water most of the time.

• Shore plants grow in wet soil at the edge of the pond.

Consumers

• Zooplankton are microscopic animals that eat phytoplankton or smaller

zooplankton. Some are single-celled animals, tiny crustaceans, or tiny
immature stages of larger animals. Zooplankton floats about in the open water
portions of the pond and is important food for some animals.

• Invertebrates include all animals without backbones. Macroinvertebrates are

big enough to be seen with the naked eye. Some of them are only found in
clean water.

• Vertebrates are animals with backbones. In a pond these might include fish,
frogs, salamanders, and turtles.
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Decomposers

Animal waste and dead and decaying plants and animals form detritus on the
bottom of the pond. Decomposers, also known as detritovores, are bacteria
and other organisms that break down detritus into material that can be used
by primary producers, thus returning the detritus to the ecosystem. As this
material decomposes it can serve as a food resource for microbes and
invertebrates. During decay microbes living on detritus can pull nutrients
from the overlying water thus acting to improve water quality. In the process
of breaking down detritus, decomposers produce water and carbon dioxide.

Conclusion

People, animals and plants depend on healthy ecosystems. Our everyday

lives and luxuries would not be possible without their services and resources
(SER). In A Sand County Almanac, author and ecologist Aldo Leopold states,
"We abuse the land because we regard it as a commodity belonging to us.
When we see land as a community to which we belong, we may begin to use it
with love and respect." Restoration gives us an opportunity to improve our
relationship to the ecosystems we depend on, and allows us to become a
constructive part of the communities that create our region's natural
environment.

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