SNC 1D Ecosystems preserving biodiversity
Transcript SNC 1D Ecosystems preserving biodiversity
Threats to Biodiversity
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:
Forests can be
logged or cleared
in North America
are almost three
times the average
Wetlands cover 6% of Earth’s surface
Plants, turtles, snakes, mink and 1000’s more live in
Migrating birds use them to feed and rest
Plants that grow there filter sediment and pollution from
Often drained for farming or building homes.
90% of wetlands around lake Ontario have been destroyed.
Alien species: is accidentally or deliberately
brought into a new location.
Introduced species, non-native 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.
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
Asian Round Goby
also probably came
in ballast water
We’re not sure of
their impact yet, but
their population is
estimated in the
billions in Lake Erie.
The use or extraction of a resource until it is
Passenger pigeon once 5 billion, last one died in
Yellowfish tuna and Atlantic cod: over-fished and
reduced by 90%
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
Background extinction: apparent over long periods
as ecosystems change, some species become
Mass extinction: relatively sudden ecosystem
change. Example: dinosaurs (caused by an
• 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