Pond Ecosystem Experiment

Aim : To study the biotic factors of a pond.

Requirements : Few glass or tin containers, insect net, sheet for mounting specimens, dessecting box, pH paper, thermometer, filter paper, beaker, funnel, watch glass, slide, cover slip, microscope, distilled water, formalin, rectified spirit and safranin stains etc.

Theory : The relationship that exists between the biotic community and an abiotic environment is termed as 'ecosystem'. Pond is an example of a fresh water ecosystem in which, like other ecosystems, there are two main components; abiotic component and biotic component.

Abiotic component of pond consists of water, dissolved minerals, oxygen and carbon-di-oxide. Solar radiations are the main source of energy. Biotic components includes : Producers, consumers, decomposers & transformers.

1. Producers : The autotroph, the plants which produce their own food e.g. green plants.

2. Consumers : The heterotrophs, the organism which depend on the producers for their food e.g. Herbivorous and carnivorous animals.

3. Decomposers : The saprophytic organisms (mainly in micro organisms) which decompose the wastes and dead bodies of plants and animals into inorganic materials e.g. bacteria.

Study of Fresh Water Ecosystem......185

Procedure : Note the different types of plants growing around and in the pond. Collect sample of these in the containers for preservation and identification. The containers should be half filled with 10% formalin solution to preserve plants.

Similarly, note the different types of animals present in the pond and collect samples of these. Collect samples of water from the different zones of the pond in the containers in order to examine them under the microscope. Observations:

Classified bio-data of pond

On the basis of water depth and types of vegetation and animals there may be three zones in a pond : littoral, limnetic and profundal. The littoral zone is the shallow water region which is usually occupied by rooted plants. The limnetic-zone ranges from the shallow to the depth of effective light penetration and associated organisms are small crustaceans, rotifers, insects and their larvae and algae. The profundal zone is the deep water part where there is no effective light penetration. The associated organisms are snails, mussels, crabs and worms.

1. Producers : The main producers in pond ecosystem are algae and other aquatic plants, such as Azolla, Hydrilla, Potamogeton, Pistiam, Wolffia, Lemma, Eichhornia, Nymphea, jussiaca etc. These are either floating or suspended or rooted at the bottom.

2. Consumers : In a pond ecosystem, the primary consumers are tadpole larvae of frogs, small fishes and other aquatic animals which consume green plants and algae as their food. The secondary consumers are, frogs, big fishes, water snakes and crabs etc. In the pond, besides the secondary consumers, there are consumers of highest order, such as water-birds, turtles and man etc.

3. Decomposers : When aquatic plants and animals die, a large number of bacteria and fungi attack their dead bodies. These microorganisms are called decomposers.

Conclusion:

(i) Reception of radiant energy of sun.

(ii) Manufacture of organic materials from inorganic ones by producers (photosynthesis).

(iii) Consumption of producers by consumers and further elaboration of

consumed materials and

(iv) After the death of producers and consumers, complex organic compounds are degraded and finally converted by decomposers and converters into such forms as are suitable for reutilization by producers.

As a result of ecosystem, there is transfer of both energy and nutrients from producers to consumers and finally to decomposers and transformers level. In this transfer there is a progressive decrease of energy but nutrient component is not diminished and it shows cycling from abiotic to biotic and vice versa.

Aim : To study the abiotic factors of a pond.

Procedure : Light: Watch the period ef light. What is its direction ? Is the light diffused or direct ? does the light affect the life ? If yes, note how ?

Soil: Take some soil from the bottom of a pond. Keep it on filter paper in a funnel. Wash it, collect the filtrate and detect the chemical nature of soil by testing it. The residue over filter paper is seen under microscope. Categorize the soil whether it is clay, loam or sand. Sketch some soil particles seen under the microscope.

Temperature : Put a thermometer in water tying with a float. Note the temperature four times a day (morning, noon, evening and night). What temperature dominates in the pond ? What are minimum and maximum temperatures ? Compare the atmospheric temperature with that of pond.

Water: Collect water from different zones of pond. Note its colour, transparency, turbidity and its alkaline or acidic nature with the help of PH papers.

The presence of fats or oils is detected by putting few drops of pond water on a paper. If the oil or fat is present, the water will leave a greasy mark on the paper.

The chemicals present in the water may be detected with the help of various chemical tests.

Study the pond in different seasons so as to note the seasonal changes in biotic community in relation to the abiotic environment of a particular region. Study food chain, percentage of different communities in different conditions and so on.

Pond Ecosystem: Experiment, Studing Ecosystem of a pond, Experiment of Pond Ecosystem