Problems with Energy Flow through Ecosystems

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Problems with Energy Flowthrough Ecosystems
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Energy transfer between trophic levels is
inefficient

• Only 10 of the energy present in a given trophic
  level can be found in the next level.
• So the number of organisms that can be supported
  at each level also goes down each time
• What happens to toxins?

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Biological Magnification

• Harmful substances like pesticides accumulate in
  higher concentrations in higher trophic levels
• Many such toxins accumulate in fat because they
  are lipid-soluble
• E.g. DDT accumulation in birds affects ability to
  deposit calcium in eggshells, even found in human
  breast-milk!

4
Energy Flow vs. Nutrient Cycling

• Energy flows through ecosystems - that is, it
  enters the ecosystem via sunlight, is stored
  temporarily in complex molecules, and ultimately
  leaves it in the form of heat.
• Nutrients cycle within ecosystems - that is, they
  are atoms (Carbon, Nitrogen, Phosphorous) that
  stay within the ecosystem and are found at
  different times in different parts of the system.

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The Big Picture Energy Flow and Nutrient Cycling