3.5: Biodiversity under Attack
pg. 92
Extinct: no longer existing on Earth.
There are 180 chameleons in this world. 59 different species are only found
on the Island of Madagascar. The habitats for chameleons on Madagascar
are being destroyed through forestry practices. This will lead to a number of
species dying off.
Biodiversity Hotspots
Area with a large biodiversity, are known as biodiversity hotspots and are
found in natural undisturbed ecosystems where many home species rarely
seen outside of the ecosystem. There are 25 identified hotspot areas found on
Earth, and Madagascar is just but one.
Most of these hotspots are threatened by human encroachment and activity.
The removal of trees destroys animal habitats, pollution by chemicals; such
as, industrial waste or fertilizer reduces water quality, threatening aquatic
organisms. Strip mining destroys habitats and removes vital resources
important terrestrial organisms. Humans need to take extra care to preserve
these hotspots to keep the healthy and sustainable.
The Range of Biodiversity in Ontario
The greatest biodiversity is found in the tropics and decreases as you move
towards the poles. Ontario, have more species in the south and fewer species
in the north. Humans populate areas in the same manner based on habitat
and food availability. Humans are a greater threat to southern Ontario then
the north.
- More natural ecosystems are cleared for farming, housing, or road
construction.
- More pollution I created, which can damage ecosystems and the
organism that live in them.
Species at Risk
Biodiversity is threatened by the extinction of organisms, biodiversity
decreases. The Committee on the Status of Endangered Wildlife in Canada
(COSEWIC) is responsible for monitoring the status of species. The
governments, universities, other agencies and Aboriginal groups make up
the committee, and they use collected data on existing species to monitor
and group species into four categories; special concern, threatened,
endangered, extirpated, and extinct.
Species Extinction
Natural catastrophes or gradual changes to habitat and climate can lead to
species extinction if they fail to adapt to their new surroundings.
Human Activity and Extinction Rates
Human activity is the greatest threat to species, and it occurs over a relative
short period of time. Organisms have no time to adapt. Humans disrupt
ecosystems; exploit new species as they are found. When humans reached
North America 10 000 years ago 80 species were soon extinct; sabre-tooth
cat, mammoth, and stellar’s sea cow.
Figure 4: Of the 167 species a risk in Ontario’s deciduous forest, 4 species are extinct, 13
are extirpated, 72 are endangered, 39 are threatened, and 39 are of special concern.
Species at Risk in Canada
There are still species becoming extinct during our lifetime, Blanding turtle
is threatened by habitat loss and needs to be protected. Polar bears are of a
special concern due to melting sea ice and green house gases increasing the
Earth’s temperature.
Over 700 species of vertebrates have become extinct in the last 4000 years,
12 were from Canada. Still there are 167 species are at risk (extirpated) of
becoming extinct in Ontario’s deciduous forests.
Reasons to Protect Biodiversity
Ecosystem with high biodiversity are healthy and more stable, therefore it is
important to protect them.
- ensure ecosystem stability and sustain all life forms.
- Provide natural processes to produce oxygen, carbon dioxide, and
nitrogen that protect our planet.
- Help species adapt to changes in their environment.
- Provide raw materials for food, clothing, and medicine.
- Enhance our quality of life by adding variety to our surroundings.
- Help shape our culture and inspire poets, painters, and writers.
Species at Risk
Classification
Definition
Special concern
May become
threated or
endangered b/c
of various
factors
Likely to become
endangered if no
action is taken
In immediate
danger of
becoming
extirpated or
extinct
No longer exists
in the wild in a
specific area
No longer exists
on Earth
Threatened
Endangered
Extirpated
Extinct
Number Examples
of
species
(2009)
Polar bear, great blue
heron, Atlantic cod
160
145
244
23
13
Humpback whale, wood
bison, Kentucky coffee
tree
Barn owl, swift fox,
northern cricket frog
Paddlefish, grey whale
Great auk, passenger
pigeon, sea mink
Check Your Learning:
Questions 1 – 10, pg. 95
Wrap Up:
- Biodiversity hotspots are under attack by human activity.
- COSEWIC categories at risk species as extirpated, endangered, threatened,
or of special concern.
- Extinction rates have increased due to human disruption of ecosystems.
- Protecting biodiversity ensures ecosystems stability ad sustains all life
forms.