This document provides an overview of aquatic ecosystems, including definitions, types, characteristics, threats, and solutions. It begins with definitions of ecosystems and descriptions of the two main types - marine ecosystems, which cover 71% of the Earth's surface, and freshwater ecosystems, which include lakes, rivers, and wetlands. It then discusses characteristics like abiotic factors, flora and fauna, and functions. Threats to aquatic ecosystems are reviewed, like pollution, development and invasive species. The document concludes with potential solutions such as education, stakeholder participation, pollution reduction, and habitat restoration.

2. INDEX
TOPIC
PAGE NO.
INTRODUCTION TO ENVIRONMENTAL
SCIENCE
ABOUT ECOSYSTEMS
AQUATIC ECOSYSTEMS
TYPES
FUNCTIONS
CHARACTERISTICS
FLORA & FAUNA
THREAT TO AQUATIC ECOSYSTEMS
SOLUTIONS AND VIEWS
SNAPSHOTS
REFERENCES
1
3
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3. INTRODUCTION TO
ENVIRONMENTAL SCIENCE
Environmentalscienceis
the interdisciplinaryacademic
fieldwhich systematically studieshuman interactionwith
theenvironmentin the interests of solving complex problems.
It is a broad field of study that includes also the natural
environment,builtenvironment, andthesets of relationships
between them. The field encompasses study in basic
principles of ecology and environmental science, as well as
associated
subjects
such
asethics,policy,politics,law,economics,philosophy,environmen
tal
sociologyandenvironmentaljustice,planning,pollution
controland natural resource management.
Whystudy environmental science?



You live here. There's only one planet so far that can support
human life.
You need to know how to protect your environment.
You need to know what has already been done to harm the
environment so that you can work to repair the damage.
We humans are currently undergoing a population explosion,
numbering over 6.5 billion people and growing. Most scientists
are convinced that this is an unsustainable population size and
that we must reduce our growth rate. While many developed

4. countries have reduced their population growth rates, most
developing countries have high birth rates.
The prodigious increase in the human population has had and is
still having devastating effects on the environment. This is
especially true of non-renewable resources, such as fossil fuels,
and the output of excessive carbon dioxide and other
greenhouse gases as a consequence.
The study of Environmental Science promotes the development
of problem-solving skills. Working in the field of
environmental science provides a wide variety of subjects and
problems to challenge and expand your skills, as well as the
satisfaction of knowing you are helping to improve the quality
of our lives and that of the planet.
Why Is Environmental Education Important?
Our nation’s future relies on a well-educated public to be
wise stewards of the very environment that sustains us, our
families and communities, and future generations. It is
environmental education which can best help us as individuals
make the complex, conceptual connections between economic
prosperity, benefits to society, environmental health, and our
own well being. Ultimately, the collective wisdom of our
citizens, gained through education, will be the most
compelling and most successful strategy for environmental
management.
Yet studies consistently reveal that the public suffers
from a tremendous environmental literacy gap that appears to
be increasing rather than decreasing. For example, two-thirds

5. of the public fail even a basic environmental quiz and a
whopping 88 percent of the public fail a basic energy quiz.
These same studies found that many people think the ocean is
a source of fresh water and some believe that hydropower is
world's top energy source.Environmental education also
increases student engagement in science.

6. ABOUT ECOSYSTEMS
An ecosystem is a community of living organisms in
conjunction with the non-living components of their
environment, interacting as a system.These biotic and abiotic
components are regarded as linked together through nutrient
cycles and energy flows. As ecosystems are defined by the
network of interactions among organisms, and between
organisms and their environment, they can come in any size
but usually encompass specific, limited spaces although some
scientists say that the entire planet is an ecosystem.Energy,
water, nitrogen and soil minerals are other essential abiotic
components of an ecosystem.
The energy that flows through ecosystems is obtained
primarily from the sun. It generally enters the system
through photosynthesis. By feeding on plants and on one
another, animals play an important role in the movement of
matter and energy through the system.By breaking down dead
organic matter,decomposers release carbon in to the
atmosphere and facilitate nutrient cycling by converting
nutrients stored in dead biomass back to a form readily used
by plantsand other microbes.

7. Ecosystems are controlled both by external factors such
as climate and some internal factors. They control the overall
structure of an ecosystem and the way things work within it,
but are not themselves influenced by the ecosystem.Other
external factors include time and potential biota. Ecosystems
are subject to disturbances and are in the process of
recovering from past disturbances.Ecosystems in similar
environments that are located in different parts of the world
can have very different characteristics simply because they
contain different species.
Internal factors not only control ecosystem processes but
are also controlled by them and are often subject to feedback
loops.While the resource inputs are generally controlled by
external processes like climate and parent material, the
availability of these resources within the ecosystem is
controlled by internal factors like decomposition, root
competition or shading.
Biodiversity affects ecosystem function. Ecosystems
provide a variety of goods and services upon which people
depend.
Classifying
ecosystems
into
ecologicallyhomogeneous units is an important step towards
effective ecosystem management, but there is no single,
agreed-upon way to do this.

8. AQUATIC ECOSYTEM
An aquatic ecosystem is an ecosystem in a body of
water. Communities of organisms that are dependent on each
other and on their environment live in aquatic ecosystems.

10. TYPES
The two main types of aquatic ecosystems are marine
ecosystems and freshwater ecosystems.
MARINE ECOSYSTEMS
Marine ecosystems cover approximately 71% of the
Earth's surface and contain approximately 97% of the planet's
water.They are distinguished from freshwater ecosystemsby
the presence of salts, in the water. Approximately85% of the
dissolved
materials
inseawaterare sodium and
chlorine.Seawaterhas an average salinity of 35 parts per
thousandof water.Actual salinity varies among different
marineecosystems.
Marine ecosystems can be divided into many zones
depending upon water depth and shoreline features.
Theoceanic zone is the vast open part of the ocean where
animals such as whales, sharks, and tuna live.
The benthic zone consistsof substrates below water where
many invertebrates live. The intertidal zone is the area
between high and low tides. It is termed the littoral zone.
Other near-shore (neritic) zonescan include estuaries, salt
marshes, coral reefs,lagoonsand mangrove swamps. In the
deep
water, hydrothermal
ventsmayoccur
where chemosynthetic sulphur bacteria form the base of the
food web.
Classes of organisms found in marine ecosystems
includealgae,din flagellates,corals,cephalopods,sharks

11. andechinoderms. Fishes caught in marine ecosystems are the
biggest source of commercial foods obtained from wild
populations.
Environmental problems concerning marine ecosystems
include unsustainable exploitation of marine resources (for
example overfishing of certain species), marine
pollution, climate change, and building on coastal areas
FRESHWATER ECOSYSTEMS
Freshwater ecosystems cover 0.80% of the Earth's
surfaceand inhabit 0.009% of its total water. Freshwater
ecosystems contain 41% of the world's known fish species.
There are three basic types of freshwater ecosystems:
Lentic
They are slow moving waterbodies like ponds,
and lakes.
Lotic
They are faster moving water bodies
likestreamsandrivers.
Wetlands
They are the areas where the soil is saturated or
inundated for some of the time.

12. LENTIC (LAKE) ECOSYSTEM
They can be divided
into zones. The first, the
littoral zone, is the
shallow zone near the
shore. This is where
rooted
wetland
plantsoccur.
The
offshore is divided into
two zones, an open water zone and a deep water zone. In the
open water zone sunlight supports algaeand the species that
feed upon them. In the deep water zone, sunlight is not
available and the food web is based on detritus entering from
the littoral and photic zones. Inland from the littoral zone one
can also frequently identify a riparian zone which has plants
still affected by the presence of the lake. This can include
effects from windfalls, spring flooding, and winter ice
damage. The production of the lake as a whole is the result of
production from plants growing in the littoral zone, combined
with production from plankton growing in the open water.
Wetlands can be part of the lentic system, as they form
naturally along most lakeshores, the width of the wetland and
littoral zone being dependent upon the slope of the shoreline
and the amount of natural change in water levels, within and
among years. Often dead trees accumulate in this zone, either
from windfalls on the shore or logs transported to the site
during floods. This woody debris provides important habitat

13. for fish and nesting birds, as well as protecting shorelines
from erosion,
Two important subclasses of lakes are ponds and
waterreservoirs. Over long periods of time, lakesmay
gradually become enriched by nutrients and slowly fill in with
organic sediments. When humans use the watershed, the
volumes of sediment entering the lake can accelerate this
process. The addition of sediments and nutrients to a lake is
known as eutrophication.
Ponds are small bodies of freshwater with shallow and
still water, marsh, and aquatic plants. They can be further
divided into four zones: vegetation zone, open water, bottom
mud and surface film. The size and depth of ponds often
varies greatly with the time of year. Many ponds are produced
by spring flooding from rivers.There is usually a diverse array
of aquatic life, with algae, snails, fish, beetles, water bugs,
frogs, turtles, otters and muskrats. Top predators may include
large fish, herons or alligators. Since fish are a major predator
upon amphibian larvae, ponds that dry up each year,often
known as vernal pools, thereby killing resident fish provide
important refuge for amphibian breeding. Some ponds are
produced by animal activity, including alligator holes and
beaver ponds, and these add important diversity to landscapes.

14. LOTIC (RIVER) ECOSYSTEM
The major zones in
river
ecosystems
are
determined by the river
bed's gradient or by the
velocity of the current.
Faster moving turbulent
water typically contains
greater dissolved oxygen,
which supports greater biodiversity than the slow moving
water. These form the basis for the division of rivers
into upland and lowland rivers. The food base of streams
within riparian forests is mostly derived from the trees, but
wider streams and those that lack a canopy derive the majority
of their food base from algae. Anadromous fish are also an
important source of nutrients. Environmental threats to rivers
include loss of water, dams, chemical pollution
and introduced species.A dam produces negative effects that
continue down the watershed. The most important negative
effects are the reduction of spring flooding, which damages
wetlands, and the retention of sediment, which leads to loss of
deltaic wetlands.

15. WETLANDS
Wetlands
are
dominated
by vascular
plants that have adapted to
saturated soil.There are four
main types of wetlands:
swamp, marsh, fen and bog.
Wetlands are the most
productive
natural
ecosystems in the world because of the proximity of water and
soil. Hence they support large numbersof plant and animal
species. Wetlands are often converted into dry land
with dykes and drains and used for agricultural purposes. The
construction of dykes and dams has negative consequences for
individual wetlands and entire watersheds. Their closenessto
lakes and rivers means that they are often developed for
human settlement.Once settlements are constructed and
protected by dykes, the settlements then become vulnerable to
land subsidence and ever increasing risk of flooding.

16. FUNCTIONS
Aquatic ecosystems perform important environmental
functions. They recycle nutrients, purify water, attenuate
floods, recharge ground water and providehabitats for
wildlife. Aquatic ecosystems are also usedfor human
recreationand are very important to thetourism industry,
especially in coastal regions.

17. CHARACTERISTICS
ABIOTIC CHARACTERISTICS
Some of the important abiotic environmental factors of
aquatic ecosystems include:
substrate type
water depth
nutrient levels
temperature
salinity
flow
dissolved oxygen
Nutrient levels
BIOTIC CHARACTERISTICS
The biotic characteristics are mainly determined by the
organisms that occur. Wetland plants may produce dense
canopies that cover large areas of sediment. Snails or geese
may graze the vegetation leaving large mud flats. Aquatic
environments have relatively low oxygen levels, forcing
adaptation by the organisms found there. Other biotic
characteristics are more subtle and difficult to measure, such
as the relative importance of competition, mutualism or
predation. There are a growing number of cases where
predation by coastal herbivores including snails, geese and
mammals appears to be a dominant biotic factor.

18. FLORA & FAUNA
AUTOTROPHIC ORGANISMS
Autotrophic organisms are producers that generate
organic compounds from inorganic material. Algae use solar
energy to generate biomass from carbon dioxide and are
possibly the most important autotrophic organisms in aquatic
environments.The more shallow the water, the greater the
biomass contribution from rooted and floating vascular plants.
Chemosynthetic bacteria are found in benthic marine
ecosystems. These organisms are able to feed on hydrogen
sulphide in water that comes from volcanic vents.
HETEROTROPHIC ORGANISMS
Heterotrophic organisms consume autotrophic organisms
and use the organic compounds in their bodies as energy
sources and as raw materials to create their
own biomass.Euryhalineorganisms are salt tolerant and can
survive in marine ecosystems, while stenohaline or salt
intolerant species can only live in freshwater environments.

19. THREAT TO AQUATIC
ECOSYSTEMS
The health of an aquatic ecosystem is degraded when the
ecosystem's ability to absorb a stress has been exceeded. A
stress on an aquatic ecosystem can be a result of physical,
chemical or biological alterations of the environment.
Physical alterations include changes in water temperature,
water flow and light availability. Chemical alterations include
changes in the loading rates of bio stimulatory nutrients,
oxygen consuming materials, and toxins. Biological
alterations include over-harvesting of commercial species and
the introduction of exotic species.
Human populations can impose excessive stresses on
aquatic ecosystems.There are many examples of excessive
stresses with negative consequences. The environmental
history of the Great Lakes of North America illustrates this
problem, particularly how multiple stresses, such as water
pollution, over-harvesting and invasive species can combine.

20. SOLUTIONS AND VIEWS
Some of the remedial measure for long termsustainability of
aquatic ecosystems includes:
Educating about water-related issues is a beneficial long-term
measure for achieving sustainable lake use.
Environmental education centres located adjacent to wetlands,
rivers & other natural features enhance public awareness of the
feature.
Citizens and other stakeholders should be encouraged to
participate meaningfully in identifying and resolving critical
problems.
Development of recreational zones by developing gardens,
parks and introduction of water sports.
Construction of a boundary wall after proper survey to prevent
encroachment.
Reducing the pollution of the lake and improving the water
quality by disiltation, Bio-Remediation, and through various
measures such as flap gates, construction of dhobi ghats and
toilets, watershed management techniques, etc.
Building embankments, walkways and pathways to the water
bodies
Planting trees, and creating gardens.
Installing docks, deploying boats and canoes.
Allocating funds for annual maintenance.

21. SNAPSHOTS

22. REFERENCES
www.google.com
http://en.wikipedia.org/
www.moef.nic.in
www.environmentministry.gov.in