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

• b) Draining Wetlands• Often drained for farming, construction or

mosquito control.• *Note 90% of wetlands along lake Ontario have been

destroyed.

http://www.corbisimages.com/stock-photo/rights-managed/AY001968/watermelon-patch-on-drained-wetlands

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.

• Examples: • i) European Earwig• ii) Giant Hogweed. • https://www.youtube.com/watch

?v=rPeg1tbBt0A

• http://humberetc.com/2011/04/13/giant-hogweed-can-cause-burns-blindness/http://humberetc.com/2011/04/13/giant-hogweed-can-cause-burns-blindness/

• 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://en.wikipedia.org/wiki/File:Zebra_mussel_infestation_Ormond_Lock.jpg

http://en.wikipedia.org/wiki/File:Zebra_mussel_GLERL_3.jpg

• 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.

http://www.dnr.state.oh.us/Default.aspx?tabid=22723

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.

• e.g. Salmon populations may be connected to the health of temperate rainforests in B.C.

http://www.jrmartinmedia.com/2011/07

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.

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.

http://www.dailymail.co.uk/news/article-1270679/Scientists-step-closer-bring-mammoth-dead.html

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

• Beluga whales• American Bison• Cougar• Black-footed ferret• Northern Fur Seal• Wolverine• Marmot• +many more

………. http://www.photosshow.com/beluga-whale/