Food Provide energy and nutrients like carbohydrates, fats and proteins essential for living organisms.The flow of energy in the ecosystem is linked closely to the nutrients flow in it.This means that chemical energy in the form of Carbohydrates ‚fat ‚protein and other nutrients get transferred to consumers.Nutrient cycle through the ecosystem and the energy within the ecosystems help in recycling of nutrients.
Food chain
In a food chain the food energy is transformed from a given source through a series of species each of which eats the one before itself in the chain. The Repeated series of eating and being eaten is always initiated with green plants which convert Radiant energy into chemical energy which is stored in food. A very simple food chain is:-
Grass-> Goat -> Man
In the transfer of food energy some proportion of energy is lost as heat. the number of length a step in a food chain is usually 4 to 5.Aquatic ecosystem microscopic green plants called phytoplankton and algae play the role of producers.
Three types of food chains can be distinguished on the basis of organism that constitutes the first trophic level. these are:-
- Grazing food chain
- Detritus food chain
- Auxiliary food chain
i) Grazing food chain:-
In this food chains green plants are autotrophs from the first trophic level. cow , deer grazing in the field represent a grazing food chain.Similarly eating of phytoplankton tonic algae by zooplankton and fish is another example of grazing food chain.In most ecosystem only a small proportion of energy flows through grazing food chains.
At each step significant amount of organic matter is transferred to detritus food chain through Death ‚Decay and excretion by living organisms.Ocean food chains are among the longest having up to five links why forest type consists of three or four Lines .
The long length of grazing food chain in aquatic ecosystems occurs because Phytoplankton and zooplankton are small in size. The chiefly compromise the first two trophic levels. if there are many small herbivores at level to the screen that the carnivores at level 3 also can be relatively small and numerous.An additional carnivore level can be accommodated before the last level represented by a relatively small number of of large Carnivores.
ii) Detritus Food chain
Detritus food chains begin with dead organic matter which is an important source of Energy .A large amount of organic matter is contributed by the death of plants, plant parts animal and their excretion product.
Various species of microscopic fungi bacteria and other saprophytes play a prominent role in decomposing organic matter to obtain energy needed for the survival and growth.In the process the release various nutrients locked in dead organic matter which are used readily by the green plants.These types of food chains are present in an ecosystem such as forest ecosystems and Shallow water communities.
Detritus food chains are interconnected with grazing Food Chain and other auxiliary food chain through certain Specific Organisms to permit transfer of energy and materials flow from One circuit to another.For example cattles to not assimilate all the energy stored in plants and undigested Residue in faeces is become available for the decomposers and detritivores.
Detritus food chain are located meaning in the soil or in the sediments of Aquatic / ecosystems.The are necessary for self sustained and maintenance of a ecological balance.Detritus Food chains are of Great Value for modern man for maintenance of activities such as seed is treatment and control of water pollution.
Most of the natural ecosystems possess both grazing and detritus type of food chains. their relative importance vary from one ecosystem to another. in Terrestrial and Shallow water detritus food chains dominant because a major portion of the energy flows occur through it circle.
In tidal marshes almost 90% of the primary production is Rooted through detritus food chains. In deep water aquatic ecosystem rapid turnover of organisms and high rate of harvest are responsible for the dominance of grazing food chains.
iii) Auxiliary food chains:-
In addition to grazing and detritus food chain there are other auxiliary food chain operating through parasites and scavengers. Some parasitic food chain May be quite Complex and may involve unrelated organisms.
A deer fed upon by internal roundworms and external ticks or a man with malarial Parasites in his blood are examples of parasitic food chain.The parasites are transmitted through various factors or unrelated intermediate host organisms.
