Threats to Biodiversity

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Threats to Biodiversity
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Habitat Loss

• Happens when either natural disasters or human
  activities change the ecosystem so much that many
  species can no longer survive.
• Natural sources of habitat destruction
• Volcanic eruptions
• Wildfires
• Droughts
• Severe storms
• Human activities
• Deforestation
• Draining wetlands
• Damming rivers

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Deforestation

• Forests can be logged or cleared and never
  replanted.
• Annual deforestation rates in North America are
  almost three times the average rate worldwide
  since 1966.

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Draining Wetlands

• Wetlands cover 6 of Earths surface
• Plants, turtles, snakes, mink and 1000s more
  live in wetlands
• Migrating birds use them to feed and rest
• Plants that grow there filter sediment and
  pollution from water.
• Often drained for farming or building homes.
• 90 of wetlands around lake Ontario have been
  destroyed.

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Alien Species

• Alien species is accidentally or deliberately
  brought into a new location.
• Introduced species, non-native species, exotic
  species.
• Sometimes they can become an invasive species
  which is a species that takes over the habitat of
  native species and upsets the equilibrium of an
  ecosystem.

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Zebra Mussels

• Native to Asia
• Introduced to Great Lakes through ballast water
• Ballast water is when cargo ships pick up water
  to keep them stable at sea and then dump the
  water in other places.
• Zebra mussels out-competed native crustaceans,
  which in turn were a major source of food for
  whitefish and smelt

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Round Gobies

• Asian Round Goby also probably came in ballast
  water
• Population grew exponentially since 1990s.
• Were not sure of their impact yet, but their
  population is estimated in the billions in Lake
  Erie.

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Overexploitation

• The use or extraction of a resource until it is
  depleted.
• Examples
• Passenger pigeon once 5 billion, last one died in
  1900s.
• Yellowfish tuna and Atlantic cod over-fished and
  reduced by 90

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Extinction

• When all individuals of a species dies.
• When death rate exceeds birth rate over a long
  period of time.
• There are patterns of extinction that happened
  naturally
• Background extinction apparent over long periods
  as ecosystems change, some species become extinct
• Mass extinction relatively sudden ecosystem
  change. Example dinosaurs (caused by an
  asteroid?)

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Restoration Ecology
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Environmental Stewardship

• The assumption of responsibility for the welfare
  of the environment
• All humans are responsible.
• In history, most humans have not thought about
  sustaining ecosystems
• Now, more and more we are concerned with the
  renewal of degraded or destroyed ecosystems
  through human intervention (restoration ecology)

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Methods of Restoration

• Reforestation the regrowth of a forest,
  naturally or by planting trees or seeds in an
  area where a forest was cut down.
• Wetlands Restoration water returned to natural
  levels, soil quality returned.
• Bioremediation using living organisms to clean
  up contaminated areas
• Plants that clean up contaminants in soil
• Bacteria that clean up oil spills
• Bioaugmentation use organisms to add essential
  nutrients to soil
• Clover added to replenish nitrogen

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Controlling Alien Species

• Biocontrol use one species to control another
  undesired species.
• Chemicals like poisoning, it kills the species.