Aquatic ecosystem 1

Aquatic Ecosystem

Prepared

By

Jhansirani.R AP/ECE

OCEAN’S

FRESH WATER

Aquatic ecosystem

• Aquatic ecosystem deals with water bodies and the biotic communities present in them

• They are of major 2 types Freshwater

Lentic (standing water) Lotic (running water)

Marine water

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Pond Ecosystem

Pond ecosystem• It is a small fresh water aquatic ecosystem where

water is stagnant• Ponds is seasonal in nature• It receives enough water during rainy season• ponds are shallow (hardly 12-15 feet) water bodies

in which sunlight can reach to its bottom• This permits the growth of the plants that grow

there.• Lotus, water lilies, duckweed, starwort and

pondweeds are commonly found here

jhansirani. R AP/ECE

Pond ecosystem• They play important role in villages• They contain several types of Algae, aquatic plants,

insects, fishes, & birds• Ponds are exposed to anthropogenic (human-generated)

pressures• They are used for washing cloths, bathing, swimming,

cattle bathing, and drinking, hence get polluted.

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Duck weed

pond weedstarwort

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Lake Ecosystem

Lake ecosystem• Lakes are usually big freshwater bodies with

standing water• They have a shallow water zone called littoral

zone• Open water zone where effective penetration of

solar light takes place called limnetic zone• Deep bottom area where light penetration is

negligible, known as profundal zone• Dal lake in Srinagar (J&K), • Naini lake in Nainital (uttarakhand)• Loktak lake in Manipur are some of the famous

lakes of our country. jhansirani. R AP/ECE

Organisms in lakes• The lakes have several types of organisms• Planktons: That float on the surface of waters

E.g. phytoplankton's like algae & Zooplanktons like Rotifers.

• Nektons: That swim e.g. fish• Neustons: That rest or swim on the surface• Benthos: That are attached to the bottom

sediments e.g. snails• Periphytons: That are attached or clinging to

other plants or any other surface e.g. crustaceans jhansirani. R AP/ECE

Profundal Zone

Stratification • Stratification: The lakes show stratification or

zonation based on temperature difference• During summer, the top waters become warmer

than the bottom waters• Only the warm top water circulates without mixing

with the cold layer thus forming a distinct zonation• Epilimnion: Warm, lighter, circulating surface

layer• Hypolimnion: Cold, viscous, non-circulating

bottom layer• Thermocline: Lies in between the 2 layers, the

region of sharp drop in temperature.jhansirani. R AP/ECE

jhansirani. R AP/ECE

Types of lakes• Oligotrophic lakes: Which have low nutrient

concentrations

• Eutrophic lakes: Which are over nourished by nutrients like nitrogen, & phosphorus, usually as a result of agricultural run-off or municipal sewage discharge. They are covered with algal blooms e.g. Dal lake

• Dystrophic lakes: They have low pH, high humic acid content and brown waters e.g. bog lakes

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Types of lakes• Endemic lakes: They are very ancient, deep and

have endemic fauna which are restricted only to that lake

e.g. The lake Baikal in Russia, the deepest lake, which is now suffering a threat due to industrial pollution.

• Desert salt lakes: That occur in arid regions and have developed high salt concentrations as a result of high evaporation

e.g. Great salt lake, Utah;

Sāmbhar lake in Rajasthanjhansirani. R AP/ECE

Types of lakes• Volcanic lakes: That receive water from magma

after volcanic eruption. They have highly restricted biota.

e.g. Tazawa lake, Japan

Crater lake, Oregon

Yellowstone lake, Wyoming• Meromictic lakes: That are rich in salts and are

permanently stratified e.g. lake Nevada• Artificial lakes or impoundments: That are

created due to construction of dams

e.g. Govindsagar lake at Bhakra-nangal.jhansirani. R AP/ECE

Crater lake(Volcanic), Oregon

Yellow stone lake (volcanic), Wyoming

Streams

Streams • These are freshwater aquatic ecosystem where

water current is a major controlling factor• Oxygen and nutrient in the water is more uniform • Land water exchange is more extensive• Stream organisms have to face more extremes of

temperature and action of currents as compared to pond or lake organism

• But they do not have to face oxygen deficiency under natural conditions.

• This is because the streams are shallow, have a large surface exposed to air and constant motion which churns the water and provides abundant oxygen

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Streams• Their dissolved oxygen level is higher than that

of ponds even though the green plants are much less in number

• Stream animals usually have a narrow range of tolerance to oxygen

• That’s why they are very susceptible to any organic pollution which depletes dissolved oxygen in the water

• Thus streams are the worst victims of industrial development.

jhansirani. R AP/ECE

River Ecosystem

River ecosystem• Rivers are large streams that flow downward from

mountain highlands and flowing through the plains fall into the sea.

• The mountain highland part has cold, clear waters rushing down as water falls with large amounts of dissolved oxygen

• The plants are attached to rocks (periphytons) and fishes are cold-water, high oxygen requiring fish like trouts

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• In the second phase on the gentle slopes, the waters are warmer and support a luxuriant growth of plants and less oxygen requiring fishes

• In the third phase, the river waters are very rich in biotic diversity

• Moving down the hills, rivers shape the land• They bring with them lots of slit rich in nutrients

which is deposited in the plains and in the delta before reaching the ocean.

• Examples Nile, Egypt Yamuna , India Mississippi-Missouri, USA

Ocean ecosystem• These are gigantic reservoirs of water covering more

than 70% of our earth surface

• Its important for survival of about 2,50,000 marine species

• Serves as food for humans and other organisms

• Gives huge variety of sea products and drugs

• They also provide iron, phosphorus, magnesium, oil, natural gas, sand and gravel

• They are major skins of carbon dioxide and play important role in Biogeochemical cycles and hydrological cycle.

• Thus regulating the earth’s climatejhansirani. R AP/ECE

• The ocean water column can be separated into 2 distinct zones: the surface zone and the deep zone

1. Surface zone• extends down to about 100- 300 meters• well mixed • known as the “mixed layer”• includes the photic zone

2. Deep zone • the rest of the water column • dark and cold with much less productivity• includes the aphotic zone

the pycnocline forms a physical barrier between the surface and deep zones

jhansirani. R AP/ECE

Ocean ecosystem

• Oceans have 2 major life zones:• Coastal zone: it has relatively warm, nutrient rich

shallow water.• Due to high nutrients and ample sunlight this is the

zone of high primary productivity

• Open sea: it is the deeper part of ocean, away from the continental shelf (the submerged part of the continent).

jhansirani. R AP/ECE

Ocean ecosystem• This is vertically divided into 3 regions Euphotic zone: Which receives abundant light

and shows high photosynthetic activity. Bathyal zone: It receives dim light and is usually

geologically active Abyssal zone: It is the dark zone, 2000 to 5000

meters deep. They have no primary source of energy i.e. solar

energy It is the worlds largest ecological unit but it is an

incomplete ecosystem.jhansirani. R AP/ECE

Aphotic zone

Euphotic zone

Seamount sessile fauna is dominated by suspension feeders

Suspension feeding invertebrates – sponges, bryozoans, corals add structural complexity and offer a great variety of

microhabitat for a diversity of species

Estuary

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Estuary• An estuary is a partially enclosed coastal area at

the mouth of a river where fresh water and salty seawater meet.

• These are the transition zones which are strongly affected by tidal action

• Constant mixing of water stirs up the slit which makes the nutrients available for the primary producers

• There are wide variations in the stream flow and tidal currents at any given location diurnally, monthly and seasonally

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• Thus organisms present in estuaries show a wide range of tolerance to temperature and salinity.

• Such organisms are known as eurythermal and euryhaline

• Coastal bays, tidal marshes are examples of estuaries.

• Estuaries have rich biodiversity and many of the species are endemic

• Many migratory species of fishes like eels and salmons spends half of the life in fresh water and half in salty water

• For them estuaries are ideal place for resting during migration, and also get abundant food.

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Coastal Bay

Tidal Marsh

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salmons

Eeljhansirani. R AP/ECE

Estuary • Estuaries are highly productive ecosystem

• River flow & tidal action provide energy subsidies for estuary thereby enhancing its productivity

• They are of much use to human beings due to their high food potential

• Thus estuaries should be managed and protected from pollution.

jhansirani. R AP/ECE