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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
jhansirani. R AP/ECE
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.
jhansirani. R AP/ECE
Duck weed
pond weedstarwort
jhansirani. R AP/ECE
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
jhansirani. R AP/ECE
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
jhansirani. R AP/ECE
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
jhansirani. R AP/ECE
• 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
jhansirani. R AP/ECE
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
jhansirani. R AP/ECE
• 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.
jhansirani. R AP/ECE
Coastal Bay
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