Download File - Mrs. Yu Science 10

Agenda
• 3.3 Notes
• BBC Video on pythons
• Video on Sea Lamprey
• Work on review package 3.3
• Work on review package 3.13.2
• Work on Practice Problems
How Introduced
Species affect
Ecosystems
3.3
Native Species
• Organisms that naturally inhabitant a given
area
• For example: “Cattails” at Lily Lake in
Merrit
Introduced Species
• Non-native organisms that enter a
new ecosystem
• Can be distributed by people,
intentionally or by accident.
Introduced Species
• These species are typically
harmless, or sometimes
beneficial.
• i.e. loosestrife-eating beetle
Invasive Species
• Harmful introduced species
• Can take over the habitat of native
species
Ex. Purple
Loosestrife
Invasive Species
• Why are they so harmful?
– Have no predators
– Could aggressively compete (negatively
affect native species, and often reduces
biodiversity as a result.)
– Reproduce quickly
Invasive Species
• Invasive species can weaken
ecosystems
–Make them more susceptible to
disease and parasitism by
micro-organisms
• Some invasive species can
change, both physically and
chemically, the make up of an
ecosystem = Habitat alteration!
Cattails:
|
Native
Species
Purple
Loosestrife:
Invasive Species
Loosestrife
eating
beetle:
Introduced
Species
The Impact of Introduced Species
• Competition: one species takes away resources from
another.
50 breeding pairs of the
European Starling were brought
to BC in the late 1800’s. It now
out-competes western bluebirds
for nesting habitat.
The American Bullfrog was
brought to BC in the 1930’s by
restaurants for their legs. It
has since taken over the
habitats of native frogs.
• Predation: if the invasive species is a predator, it
may have a huge advantage, as the native
species may have no methods to survive.
The Norway rat escaped from early
European explorer and fur-trading ships. On
Queen Charlotte Islands, they have caused a
decline in ground-nesting sea birds, such as
• .
ancient murrelets and puffins, by eating
their eggs and young.
•
West Nile virus was recently introduced to the United
States in 1999, when it started causing deaths in birds and
illness in humans in New York City. It is a vector borne
disease, carried by the mosquito.
• Disease & Parasitism: by weakening certain species, a
micro-organism invading an ecosystem can drastically
alter the entire ecosystem and the niches within it.
• Habitat Alteration: some invasive species can
change the physical structure of the ecosystem
by digging, burrowing, blocking sunlight or
changing the chemistry of the ecosystem.
Eurasian Milfoil was first
identified in Okanagan
Lake in 1970. It forms
wide, dense mats at lake
surfaces, cutting off
sunlight to organisms
below and interfering with
recreational activities. It
can grow from plant
fragments, which are
often spread by boats.
Saving an Ecosystem Under Siege
• It often takes human intervention to save established
ecosystems.
– The Garry Oak Ecosystem Recovery
Team (GOERT) is trying to save
several areas of the Garry Oak
ecosystem in BC because Garry
Oak trees are a keystone species and
they may be better suited to survive in the future than
Douglas fir forests.
– Scotch broom, English ivy and other plant species are its
biggest threats.
• Invasive Species – Animated Film
• Invasive Species - Bullfrogs