Energy Flow in Ecosystems

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Energy Flow in Ecosystems

• Science 10

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Trophic Levels

• Trophic levels refer to feeding levels in an
  ecosystem. They help to explain food and energy
  distribution in an ecosystem.
• 1st trophic level producers
• 2nd trophic level primary consumers
• 3rd trophic level secondary consumers
• 4th trophic level tertiary consumers

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Detritivores and Decomposers

• Detritivores organisms that consumes dead
  material and animal wastes including decomposers
  
• Decomposers various bacteria and fungi that
  break down dead material and animal wastes and
  extract the remaining nutrients

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• Trophic levels show the transfer of energy
  through a food chain.
• On average, only 10 of energy from one trophic
  level is transferred to the next level. Why?

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Energy Use by an Organism

• All living organisms use energy to move, grow,
  reproduce and carry out activities.
• As a result
• 30 of energy gets converted to thermal energy
  through cellular respiration
• 60 of energy gets converted into waste
• Only 10 of energy is converted into body tissue,
  usable at the next level.

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• There are various tools to explain the
  relationship between each trophic level including
  the three pyramids found on pages 14, 16 and 17.

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Pyramid of Numberspage 14

• Benefits
• It shows how MANY organisms are at each level so
  we can estimate the energy available.
• It helps explain why there are fewer organisms
  higher up the food chain

• Drawbacks
• Sometimes, small herbivores and carnivores
  outnumber the organism they consume so the
  pyramid does not reflect the energy flow.
• Think of the number of insects that can feed on a
  tree.

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Biomass the total dry mass of a given population
of organisms.
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Pyramid of Biomasspage 16

• Benefits
• Shows how MUCH of a living organism is at each
  level so we can estimate how much energy is
  available.
• Biomass can be several small organisms at a
  trophic level, or a few big organisms at a
  trophic level.

• Drawbacks
• Sometimes, producers reproduce very quickly, but
  the total biomass is lower than the primary
  consumers, making the pyramid upside down.
• Example zooplankton and algae

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Pyramid of Energy page 17

• Benefits
• A pyramid of energy demonstrates the flow of
  chemical energy through each trophic level.
• It cannot be inverted because there is always
  less energy available as you go up a trophic
  level.

• Drawbacks
• Energy pyramids do not reflect the quantity of
  organisms.