Transcript 3.3 Threats to Biodiversity

3.3 Threats to Biodiversity
1. Habitat Loss
(most significant threat to biodiversity)
Occurs when events alter an ecosystem so much
that many species can no longer survive there.
• a) Deforestation
• Occurs when forests
are logged or cleared
for human use and
are not replanted.
• (see video clip)
http://hernadi-key.blogspot.com/2008/12/global-warming-aided-by-drought.html
http://www.corbisimages.com/stock-photo/rights-managed/AY001968/watermelon-patch-on-drained-wetlands
• b) Draining Wetlands
• Often drained for farming, construction or
mosquito control.
• *Note 90% of wetlands along lake Ontario have been
destroyed.
2. Alien Invasive Species
(2nd largest threat to biodiversity)
• Species introduced to new
parts of the biosphere from
other regions;
• May be introduced on purpose
or accidentally in shipments of
food or goods.
• They take over the habitat of
native species.
• Arrive, Survive and Thrive.
http://humberetc.com/2011/04/13/giant-hogweed-can-cause-burns-blindness/
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Examples:
i) European Earwig
ii) Giant Hogweed.
https://www.youtube.com/watc
h?v=rPeg1tbBt0A
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http://humberetc.com/2011/04/13/giant-hogweed-can-causeburns-blindness/
http://en.wikipedia.org/wiki/File:Zebra_mussel_GLERL_3.jpg
http://en.wikipedia.org/wiki/File:Zebra_mussel_infestation_Ormond_Lock.jpg
• Zebra Mussels
• Native to Asia;
introduced to the
Great lakes through
ballast water in the
1980’s
• Out-competes native
mussels and other
organisms that share
the same food;
impacts other levels
in the food chain.
• (Show Video clip)
http://www.dnr.state.oh.us/Default.aspx?tabid=22723
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Round Gobies:
Introduced by ballast water in late 80’s.
Competes with native fish for spawning areas
Eat many aquatic species which affects food chains of native
species.
• 10 years after arrival, found in all 5 great lakes.
• Lake Erie population in the billions.
3. Overexploitation
• Use or extraction
of a resource until
it is depleted
• e.g.: over fishing
of Atlantic cod
• Hunting of the
passenger
pigeon.
http://en.wikipedia.org/wiki/File:Surexploitation_morue_surp%C3%AAcheEn.jpg
4. Disrupting Connectivity Across
Ecosystems
• When one species is
affected in an
ecosystem, other
ecosystems may be
impacted.
http://www.jrmartinmedia.com/2011/07
• e.g. Salmon
populations may be
connected to the
health of temperate
rainforests in B.C.
5. Extinction
• The death of all the individuals
of a species
• e.g. dinosaurs
• May happen through:
a) Background Extinction:
• Caused by slow change to
ecosystem over time.
http://www.dailymail.co.uk/news/article-1270679/Scientists-step-closerbring-mammoth-dead.html
b) Mass Extinction:
• occurs quickly
• may be caused by humans
(e.g.overexploitation) or
• by natural causes (e.g.
meteorite)
• Current extinction rates are
100-1000x higher than the
background extinction rate.
Species currently endangered
• Glass frog (central
and south america)
• Chinese giant
salamander
http://www.allpics4u.com/nature/strange-and-exotic-endangered-species.html
• Frigate Island
Beetle
• Giant Coconut
Crab (Guam and
Pacific Islands)
http://www.allpics4u.com/nature/strange-and-exotic-endangered-species.html
Canadian Endangered Species
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Beluga whales
American Bison
Cougar
Black-footed ferret
Northern Fur Seal
Wolverine
Marmot
+many more
……….
http://www.photosshow.com/beluga-whale/