Transcript SNC 1D Ecosystems preserving biodiversity

Threats to Biodiversity
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
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.
Draining Wetlands
 Wetlands cover 6% of Earth’s surface
 Plants, turtles, snakes, mink and 1000’s 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.
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.
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 outcompeted native
crustaceans, which in turn
were a major source of
food for whitefish and
smelt
Round Gobies
 Asian Round Goby
also probably came
in ballast water
 Population grew
exponentially since
1990’s.
 We’re not sure of
their impact yet, but
their population is
estimated in the
billions in Lake Erie.
Overexploitation
 The use or extraction of a resource until it is
depleted.
 Examples:
 Passenger pigeon once 5 billion, last one died in
1900’s.
 Yellowfish tuna and Atlantic cod: over-fished and
reduced by 90%
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?)
Restoration
Ecology
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)
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
Controlling Alien Species
• Biocontrol: use one species to
control another undesired species.
• Chemicals: like poisoning, it kills
the species.