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Table of contents
Energy Flow Through an Ecosystem – Trophic Levels
- The trophic level interaction involves three concepts namely
- Food Chain (previous post)
- Food Web(previous post)
- Ecological Pyramids
Ecological Pyramids
- The pyramidal representation of trophic levels of different organisms based on their ecological position (producer to final consumer) is called as an ecological pyramid.
- The pyramid consists of a number of horizontal bars depicting specific trophic levels. The length of each bar represents the total number of individuals or biomass or energy at each trophic level in an ecosystem.
- The food producer forms the base of the pyramid and the top carnivore forms the tip. Other consumer trophic levels are in between.
- The ecological pyramids are of three categories:
- Pyramid of numbers,
- Pyramid of biomass,and
- Pyramid of energy or productivity.
Pyramid of Numbers
- Pyramid of numbers represents thetotal number of individuals of different species(population) at each trophic level.
- Depending upon the size, the pyramid of numbers may not always be upright, and may even be completely inverted.
- It is very difficult to count all the organisms, in a pyramid of numbers and so the pyramid of numberdoes not completely define the trophic structure for an ecosystem.
Pyramid of numbers – upright
- In this pyramid, the number of individuals is decreased from lower level to higher trophic level.
- This type of pyramid can be seen in the grassland ecosystemandpond ecosystem.
- The grasses occupy the lowest trophic level (base) because of their abundance.
- The next higher trophic level is primary consumer – herbivores like a grasshopper.
- The individual number of grasshoppers is less than that of grass.
- The next energy level is a primary carnivore like rats.
- The number of rats is less than grasshoppers, because, they feed on grasshoppers.
- The next higher trophic level is secondary carnivore like snakes. They feed on rats.
- The next higher trophic level is the top carnivore like Hawk.
- With each higher trophic level, the number of individual decreases.
Pyramid of numbers – inverted
- In this pyramid, the number of individuals is increased from lower level to higher trophic level. E.g. Tree ecosystem.
Pyramid of Biomass
- Pyramid of biomass is usually determined by collecting all organisms occupying each trophic level separately and measuring theirdry weight.
- This overcomes the size difference problem because all kinds of organisms at a trophic level are weighed.
- Each trophic level has a certain mass of living material at a particular time called thestanding crop.
- The standing crop is measured as the mass of living organisms (biomass) or the number in a unit area.
Pyramid of Biomass – upright
- For most ecosystems on land, the pyramid of biomass has a large base of primary producers with a smaller trophic level perched on top.
- The biomass of producers (autotrophs) is at the maximum. The biomass of next trophic level i.e. primary consumers is less than the producers. The biomass of next higher trophic level i.e. secondary consumers is less than the primary consumers. The top, high trophic level has very less amount of biomass.
Pyramid of Biomass – Inverted
- In contrast, in manyaquatic ecosystems, the pyramid of biomass may assume an inverted form. (In contrast, a pyramid of numbers for the aquatic ecosystem is upright)
- This is because the producers are tiny phytoplankton that grows and reproduces rapidly.
- Here, the pyramid of biomass has a small base, with the consumer biomass at any instant exceeding the producer biomass and the pyramid assumes an inverted shape.
Pyramid of Energy
- To compare the functional roles of the trophic levels in an ecosystem, an energy pyramid ismost suitable.
- An energy pyramid represents the amount of energy at each trophic level and loss of energy at each transfer to another trophic level. Hence the pyramid isalways upward, with a large energy base at the bottom.
- Suppose an ecosystem receives 1000 calories of light energy in a given day. Most of the energy is not absorbed; some is reflected to space; of the energy absorbed only a small portion is utilized by green plants, out of which the plant uses up some for respiration and of the 1000 calories; therefore only 100 calories are stored as energy-rich materials.
- Now suppose an animal, say a deer, eats the plant containing 100 calories of food energy. The deer use some of it for its metabolism and stores only 10 calories as food energy. A lion that eats the deer gets an even smaller amount of energy. Thus, usable energy decreases from sunlight to producer to herbivore to carnivore. Therefore, the energy pyramid will always be upright.
- Energy pyramidconcept helps to explain the phenomenon ofbiological magnification– the tendency for toxic substances to increase in concentration progressively with higher trophic levels.
Ecological Efficiency
- Ecological efficiencydescribes theefficiencywith which energy is transferred from one trophic level to the next.
- The number of trophic levels in the grazing food chain is restricted as the transfer of energy follows 10 per cent law – only 10 per cent of the energy is transferred to each trophic level from the lower trophic level.
- The decreases at each subsequent trophic level is due to two reasons:
- At each trophic, a part of the availableenergy is lost in respirationorused up in metabolism.
- A part of the energy is lost at eachtransformation.
Limitations of Ecological Pyramids
- It does not consider thesame species belonging to two or more trophic levels.
- It assumes a simple food chain, something that seldom exists in nature; itdoes not accommodate a food web.
- Moreover, saprophytes (plant, fungus, or microorganism that lives on decaying matter) are not given any place in ecological pyramids even though they play a vital role in the ecosystem.
Pollutants and Trophic Level – Biomagnification
- Pollutants move through the various trophic levels in an ecosystem.
- Non-degradable pollutants (persistent pollutants), which cannot be broken down by detrivores, not only move through the various trophic levels but also remain in that tropic level for a very long duration.
- Chlorinated Hydrocarbons (Organochlorides) are the most damaging non-degradable pollutants that are long-lasting.
Chlorinated Hydrocarbons (CHC)
- CHCsare hydrocarbons in which one or more hydrogen atoms have been replaced bychlorineE.g.DDT (dichlorodiphenyltrichloroethane), endosulfan, chloroform, carbon tetrachloride, etc.
Applications of Chlorinated Hydrocarbons (CHC)
- CHCs are used in the production of polyvinyl chloride (a synthetic plastic polymer used to make PVC pipes).
- Chloroform, dichloromethane, dichloroethane, and trichloroethane are useful solvents.
- These solvents are immiscible with water (not forming a homogeneous mixture when mixed with water) and effective in cleaning applications such as degreasing and dry cleaning.
- DDT, heptachlor and endosulfan are were widely used as pesticides.
Effects of CHC
- Dioxins (toxic by-products produced when organic matter is burned in the presence of chlorine in industrial or natural processes such as volcanic eruptions and forest fires), and some insecticides, such as DDT, are persistent organic pollutants.
- DDT was widely used a few decades ago as an effective pesticide and insecticide.
- It was later identified as a persistent organic pollutant, and its usage was phased out in almost all developed countries.
- It accumulated in food chains and caused eggshell thinning in certain bird species.
- In India, it is still being used by civic administrations as a mosquito repellent (disease vector control).
- In India, traces of DDT spray used three decades ago can still be found on the walls of homes.
- Crops that are grown in fields that were sprayed with DDT in the last decades show substantial traces of the insecticide.
- DDT residues continue to be found in mammals all across the planet.
- In Arctic areas, particularly high levels are found in marine mammals.
- The traces of persistent organic pollutant are found in human breast milk.
- In some species of milk-producing marine mammals, males typically have far higher levels, as females reduce their concentration by transfer to their offspring through lactation.
- Endosulfan, one of the most widely used pesticide, is anendocrine disruptor(enhances the effect of estrogens causing reproductive and developmental damage in both animals and humans).
- Because of its threats to human health and the environment, a global ban on the manufacture and use of endosulfan was negotiated under theStockholm Conventionin 2011.
Movement of these pollutants involves two main processes:
- Bioaccumulation
- Biomagnification
Bioaccumulation
- Bioaccumulation is the gradual accumulation of pollutants, chemicals (chronic poisoning) or other substances in an organism.
- Bioaccumulation occurs when the rate of loss of the substance from the body of the organism through catabolism (breakdown of complex molecules in living organisms), or excretion is lower than the rate of accumulation of the substance.
- As persistent organic pollutants like DDT are long-lasting, the risk of bioaccumulation is high even if the environmental levels of the pollutant are not high.
Biomagnification
- Biomagnification refers to progressive bioaccumulation (increase in concentration) at each tropical level with the passage of time.
- In order for biomagnification to occur, the pollutant must have a long biological half-life (long-lived), must not be soluble in water but must be soluble in fats. E.g. DDT.
- If the pollutant is soluble in water, it will be excreted by the organism.
- Pollutants thatdissolve in fats are retained for a long time. Hence it is traditional to measure the amount of pollutants in fatty tissues of organisms such as fish.
- In mammals, milk produced by females is tested for pollutants since the milk has a lot of fat in.
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FAQs
How does energy flow through an ecological pyramid? ›
Energy Flow Through an Ecosystem
At the base of the pyramid are the producers, who use photosynthesis or chemosynthesis to make their own food. Herbivores or primary consumers, make up the second level. Secondary and tertiary consumers, omnivores and carnivores, follow in the subsequent sections of the pyramid.
The energy flow takes place via the food chain and food web. During the process of energy flow in the ecosystem, plants being the producers absorb sunlight with the help of the chloroplasts and a part of it is transformed into chemical energy in the process of photosynthesis.
Why is an energy pyramid in an ecosystem only 4 or 5 levels? ›Because of the high rate of energy loss in food chains, there are usually only 4 or 5 trophic levels in the food chain or energy pyramid. There just is not enough energy to support any additional trophic levels. Heterotrophs are found in all levels of an energy pyramid other than the first level.
Why is only 10 percent of energy transferred? ›Answer and Explanation: At each trophic level, only about 10% of energy can be passed on to the next level. This is because much of the energy that organisms consume is used to carry out their own bodily functions and growth.
How does energy flow through an ecosystem quizlet? ›In an ecosystem, energy flows from producers (plants) to primary consumers (herbivores) to secondary and tertiary consumers (carnivores). Food chains and food webs model this energy flow and these feeding relationships. Each step in a food chain is called a trophic level.
What is an ecological pyramid of energy quizlet? ›Ecological Pyramid. a diagram that shows the relative amounts of energy of matter contained within each trophic level in a food chain or food web.
What is the order of energy flow in an ecosystem? ›The energy passes from primary producers to primary consumers. From the primary consumers, the energy is passed to secondary consumers and then to tertiary consumers.
How does energy flow in the ecosystem explain with example? ›An example of energy flow in an ecosystem would begin with the autotrophs that take energy from the sun. Herbivores then feed on the autotrophs and change the energy from the plant into energy that they can use. Carnivores subsequently feed on the herbivores and, finally, other carnivores prey on the carnivores.
What is the flow of energy in an ecosystem each? ›The flow of energy in an ecosystem is always unidirectional. It is said to be unidirectional because some energy is lost in form of heat when moving from one trophic level to the next for the maintenance of the homeostasis of an organism.
What is the pyramid of energy in an ecosystem always? ›Pyramid of energy is always upright. This is because during energy transfer between adjacent trophic levels, energy is lost in the form of heat.
What is the ecological pyramid in short notes? ›
An ecological pyramid is a graphical representation of the relationship between the different living organisms at different trophic levels. Charles Elton developed the concept of the pyramid of numbers. Later, G.Evylen Hutchinson and Raymond Lindeman developed the idea of the pyramid of energy or productivity.
Why do energy pyramids only go at most 4 or 5 trophic levels and the top trophic levels have such a low population? ›Generally, there are no more than four trophic levels because energy and biomass decrease from lower to higher levels.
Why isn t 100% of the energy transferred from one level to the next? ›The reason for this is that only around 10 per cent of the energy is passed on to the next trophic level. The rest of the energy passes out of the food chain in a number of ways: it is released as heat energy during respiration. it is used for life processes (eg movement)
Why only 10% of an organism's energy moves up the food chain? ›Key Points. Energy decreases as it moves up trophic levels because energy is lost as metabolic heat when the organisms from one trophic level are consumed by organisms from the next level.
What happened to all the energy if only 10% is passed through? ›The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10 percent of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat.
What is the first step in energy flow through an ecosystem? ›3.1 The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs.
What does ecological pyramid contain? ›1: Ecological pyramids: Ecological pyramids depict the (a) biomass, (b) number of organisms, and (c) energy in each trophic level. Another way to visualize ecosystem structure is with pyramids of biomass. This pyramid measures the amount of energy converted into living tissue at the different trophic levels.
What is the most important feature of the energy flow in the ecosystem? ›The most important characteristic is the one-way street along which energy flows. The energy that is captured by the autotrophs does not revert back to solar input; that which passes to the herbivores does not pass back to the autotrophs; and so on.
What does the energy flow in an ecosystem begin with quizlet? ›Energy flow through ecosystems begins with producers. Chemical energy flow begins with consumers who obtain chemical energy by feeding on producers.
What is the flow of energy between organisms called? ›A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another. In a food chain, each organism occupies a different trophic level, defined by how many energy transfers separate it from the basic input of the chain.
Which parts of an ecosystem are part of the energy flow? ›
The energy roles within an ecosystem are producer, consumer, and decomposer. Organisms that make their own food by using the sun's energy to turn water and carbon dioxide into food through a process called photosynthesis.
How does matter flow through an ecosystem? ›The cycling of matter in the ecosystem occurs through a series of food chains, food webs, and nutrient cycles. The matter is transferred from one organism to another as all of them are interconnected with each other.
What is the flow of energy in an ecosystem always 1 point? ›Final answer: Flow of energy in an ecosystem is always unidirectional.
How each type of pyramid models energy and matter in an ecosystems? ›Pyramids of energy show relative amounts of energy available at different trophic levels. Pyramids of biomass show the total amount of living tissue at each trophic level. A pyramid of numbers shows the relative numbers of organisms at different trophic levels.
Which type of pyramid best represents energy flow through an ecosystem and why? ›Pyramids of energy are usually upright and are the best representation of energy flow and ecosystem structure.
What is an example of an energy pyramid? ›An example of an energy pyramid is the forest ecosystem. In this ecosystem the producers are green plants that make up the bottom of the pyramid. Next, are the primary consumers, then secondary consumers, and finally the tertiary consumers make up the top triangle of the pyramid.
What is the significance of the shape of the pyramid of energy? ›What is the significance of the shape of the pyramid of energy? Explanation: Pyramid of energy is always upright in shape, this is because as energy lost as heat along food chains either used in respiration or lost due to heat. So there will be decrease in energy.
What is an example of ecological pyramid? ›The pyramid of biomass may be "inverted". For example, in a pond ecosystem, the standing crop of phytoplankton, the major producers, at any given point will be lower than the mass of the heterotrophs, such as fish and insects.
Which trophic level has most energy? ›The bottom and largest level of the pyramid is the producers and contains the largest amount of energy. As you move up the pyramid, through the trophic levels to primary, secondary and tertiary consumers, the amount of energy decreases and the levels become smaller.
What happens to the other 90% of the energy at each level? ›The ten percent rule states that each trophic level can only give 10% of its energy to the next level. The other 90% is used to live, grow, reproduce and is lost to the environment as heat. All energy pyramids start with energy from the Sun which is transferred to the first trophic level of producers.
Is 100% energy transfer possible? ›
Hence energy transfer are never 100% efficient due to entropy.
Can the energy transfer in an ecosystem be 100 %? Explain why? ›In the energy flow figure, the energy used in respiration and in decay appears as unuseful heat energy because this energy does not reach to consumer of next stage. So just like in machine, in ecosystem also the energy transfer is not 100% efficient.
Why is the total energy in any one trophic level always less than the total energy in the level immediately below it? ›The amount of energy available to one trophic level is limited by the amount stored by the level below. Because energy is lost in the transfer from one level to the next, there is successively less total energy as you move up trophic levels.
Why do food chains rarely go beyond 5 trophic levels using energy explain why? ›There is only 10% flow of energy from one trophic level to the next higher level. The loss of energy at each step is so great that very little usable remains after four or five trophic levels. Hence only 4 to 5 trophic levels are present in each food chain.
What do you think will happen to the amount of energy when grass is eaten by rabbit? ›When consumed some of the energy is transferred but some of the energy is lost at each link in the chair (or trophic level). In the above example, the grass loses some energy by respiration, the rabbit loses energy by heat and waste.
When an herbivore eats a plant what happens to 90% of the energy obtained from that plant? ›The herbivore uses the energy from the plant to power its own life processes and to build more body tissues. However, only about 10% of the total energy from the plant gets stored in the herbivore's body as extra body tissue. The rest of the energy is used by the herbivore and released as heat.
What percent of energy is transferred from the sun to the level indicated? ›As you move from the sun through each trophic level, only ten percent of the energy will be carried to the next level.
How much energy would be transferred to tertiary consumers if the producers begin with 25000 kcal? ›If the producers begin with 25,000 kcal then energy transferred to the primary consumer is: 25000 x 0.10 = 2500 kcal. Energy transferred to the secondary consumer is: 2500 x 0.10 = 250 kcal. Energy transferred to the tertiary consumer is: 250 x 0.10 = 25 kcal.
What is a energy pyramid and how does the energy flows in a energy pyramid? ›An energy pyramid is a model that shows the flow of energy from one trophic, or feeding, level to the next in an ecosystem. The model is a diagram that compares the energy used by organisms at each trophic level. The energy in an energy pyramid is measured in units of kilocalories (kcal).
How is energy transferred between plants and animals? ›Explanation: The food chain begins with the sun: plants get their energy by photosynthesizing sunlight into energy, and then herbivores eat those plants to get their energy. Carnivores who then eat the herbivores are getting that sunlight passed along from sun to plant to herbivore to carnivore.
What are the 5 levels of energy pyramid? ›
Identify and describe the levels of the pyramid: producers, primary consumers, secondary consumers, tertiary consumers. Understand the role of decomposers. Know that about 10% of the energy from each level reaches the one above.
Which is the direction of energy flow through the pyramid? ›Energy flows from the bottom to the top layer of the pyramid. Approximately 10% of an organism's energy is transferred to another organism.
Which direction does energy flow in a pyramid of numbers? ›Pyramid of Energy
An energy pyramid represents the amount of energy at each trophic level and loss of energy at each transfer to another trophic level. Hence the pyramid is always upward, with a large energy base at the bottom.
The ten percent rule states that each trophic level can only give 10% of its energy to the next level. The other 90% is used to live, grow, reproduce and is lost to the environment as heat. All energy pyramids start with energy from the Sun which is transferred to the first trophic level of producers.
What is the energy cycle in the ecosystem? ›The energy cycle describes the interactions between energy sources within the Earth's environment. These interactions are very complex, and even small changes in them can lead to significant changes in long-term climate behavior. A simple illustration of the major elements of the energy cycle is shown in the figure.
What is the basic source of energy in the ecosystem? ›In most ecosystems, the ultimate source of all energy is the sun.
What is the role of each organism involved in the energy pyramid? ›The base of the pyramid is composed of species called autotrophs, the primary producers of the ecosystem. All other organisms in the ecosystem are consumers called heterotrophs, which either directly or indirectly depend on the primary producers for food energy.