03The Mystery of Easter Island

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					The Mystery of Easter Island
  The discovery of Easter Island
On Easter day in 1722, a Dutch
  ship landed on a small treeless
  island in the south Pacific. A
  small population of people
  lived on the island. Along the
  coast, there were many giant
  rock statues of human forms.
  Some of these statues were as
  tall as 10 m. How could so few
  people put together so many
  large statues? and, WHY
  ON THE ISLAND?              
      Scientists theorized and
  investigated to solve the mystery
• Carbon dating indicates that the first inhabitants
  arrived as early as 318 AD in canoes
• Archeological evidence shows that the island
  was once covered with thick forests, and fish,
  animals and vegetation suitable for a human diet
  were plentiful
• There was plenty of food, water and shelter to
  allow the population to grow considerably, and a
  rich cultured society soon established itself.
  Why, then, did the population decline? Did the
  statues have something to do with this decline?
How were the rocks moved to build
 the giant statues on the coast?

• Trees were cut down to make wooden
  frames and “rollers” to allow the heavy
  rocks to be moved more easily
  If the island was once forested,
     where did all the trees go ?

• Trees were cut down to clear the land for
  their crops

• wood was burned for warmth

• Eventually, the last tree was cut down
      When the last tree was cut
• Soil eroded away and there was no fertile
  soil left to grow crops
• There were no trees to burn to keep the
  inhabitants warm
• Wildlife that had lived in the trees lost their
  homes, food and protection and couldn’t
• Rain water ran off into the ocean instead
  of collecting in the water table
             The end result?

• Without the supporting forest, the island could
  no longer sustain the human population that had
  once thrived
• Pollen records show that by the year 800 AD,
  the forests were already depleted
• The population had grown to the point where the
  island’s resources could no longer support it
• The population had failed to conserve the
  resources they had
• Famine, and later, cannibalism, and competing
  clans led to the destruction of this society
   The Need for Sustainable
     The story of Easter Island
illustrates the need for humankind
to live in a way that is sustainable:
   resources must be used wisely
     and replaced in an ongoing
  manner to avoid their depletion.
                 What is ECOLOGY?

• the scientific study of the
  interactions of organisms with one
  another and with their physical
  and chemical environment.
What Ecology Terms do you
      already know?
      Ecology Terms you need to
       understand to get started:
• Ecosystem and sustainable ecosystem
• Biotic and Abiotic
• Lithosphere, Hydrosphere, Atmosphere, Biosphere
• Nutrients
• Aquatic ecosystem, Terrestrial ecosystem
• Predators and prey
• Niche, Consumers, producers, scavengers and
• Primary and secondary consumers
• carnivores, omnivores, herbivores
• population, community, individual
The American Eel
Reported Catches of American
Distribution and
   Life Cycle
Number of Eels Ascending the Eel
       Ladder Per Day
             Eel Case Study
• Read the article about the disappearing Eel
• Draw a food web that includes the Eel
• In this food web, identify: producers, consumers,
  herbivores, omnivores and carnivores
• Referring to your food web, how would the
  population of EACH species in your food web be
  affected by the decline of the Eel population?
• Answer Questions 1 and 2 under “Your Turn”
  and be prepared to discuss in class tomorrow.

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