a pondfish ecosystem.ppt

7/29/2019 A Pondfish ecosystem.ppt

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A freshwater ecosystem


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Pondfish Ecosystem

An ecosystem is a dynamic complex of plant,animal,and microorganism communities and thenonliving environment, interacting as a functionaluit.

The non-living substances of pondecosystem include the inorganic andorganiccompounds. These compoundsremain in solution in pond water, in reservein bottom deposits as well in the livingorganisms - both plants and animals.


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The living organisms (biotic community) in a pond

ecosystem, consisting of all sorts of plants

and animals, are broadly categorized into twomain groups:

The autotrophic commun i ty v iz. the

producersinclude all the green plants whichproduce complex organic substances or cell

materials from inorganic soluble nutrients in

presence of sun light (photosynthesis). The producers are of two types :phytoplanktonand macrophytes.


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The minute floating algae orphytoplankton

distributed in the pond water column mainly

throughout the light-limited limnetic zone. Abundance

of phytoplankton population in water gives greenish

colour. Production of phytoplankton is thus dependent on

sun light and available soluble nutrients in water. Tropical

fish ponds are generally found rich in natural foodorganisms as the sun light duration is longer.

The macrovegetation, though fall under producer

group, in reality, their contribution is negligible in

primary productivity of well managed fish pond. Theyare, however, found inhibitor in fish production

system if not utilized properly as fish feed.


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The heterotrophic communityin a fish pondecosystem comprising of two major groups oforganisms namely:

The consumers - the organisms depending on otherorganisms living or dead for food such as zooplankton,insect larvae, fish etc. The consumers group (benthicinvertebrates and bottom feeding fish) subsisting on

organic detritus are called detritivores. The decomposers - the group of heterotrophic organisms

such as bacteria and fungi break down the dead plantsand animals and release partially decomposed

materials and inorganic nutrients into pond water forutilization by the producers viz. phytoplankton andmacrophytes. The decomposers are most abundant atthe pond bottom where the dead plants and animal

bodies are most abundant.


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The food chains or energy pathways in a pond

ecosystem are of two types: the autotrophic

food chain and the heterotrophic food chain. Autotrophic food chain - It is the solar energy

dependent food chain which begins with the

plants, basically phytoplankton, at the pondsurface and then sequentially pass through

primary consumers (zooplankton and

planktivoursfishes) to secondary and tertiary

consumers (carnivorous insects and fishes).


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The pathways in autotrophic food

chain are:

Phytoplankton fish

Phytoplanktonzooplankton fish

Phytoplanktonzooplankton aquatic

insects fish predator fish


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Heterotrophic food chain - This energy

pathway starts from the decomposition of dead

organic matters by the decomposing bacteriaand fungi at the pond bottom and then pass

through zooplankton - aquatic insects to fishes

(secondary and tertiary consumers) as shown

below :

Bacteria fish

Bacteria protozoa fish

BacteriaProtozoa zooplankton Aquatic

insect larvae fish


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Bacteria


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Aquatic Insects


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Floating Plants


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Submerged Plants


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Emergent Plants


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The productivity of a fish pond depends

on the availability of dissolved

nutrients in pond water which can beutilized forproduction of organic

materials by the producers (mainlyphytoplankton) using solar energy.


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The sources of pond nutrients may be oforganic and/or inorganic origin. Organic

manure mainly supports the heterotrophic foodchain while the inorganic fertilizers supportsthe autotrophic food chain. Both the pathwaysare closely inter-linked to each other.

However, in most fish ponds, productionlargely depends on the solar energydependent autotrophic food chain, but theponds receiving high quantity of organic

manures on regular basis have significantheterotrophic use of wastes by bacteria andprotozoa.


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Fish production not only depends on

the rich food chains but also largely

on the stocking density of fish as well

as the species combination having

different feeding and spatial niches -so that total fish food organisms of a

pond originated from both the food

chains are properly utilized by thefish.


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The EndMan Jadda Wa Jadda

a pondfish ecosystem.ppt

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