Notes+on+threats+to+biodiversity

toc =Threats to Biodiversity=
 * **biodiversity** = the number of different types of organisms
 * natural and man-made events threaten biodiversity

#1 Habitat Loss

 * due to natural disaster or human activities
 * destroys where organisms live and reproduce
 * e.g. of human activities that cause habitat loss:

i. deforestation

 * cut down trees
 * burn Amazon rain forest for cattle farming ("burn Amazon rain forest for burgers")
 * often humans can only use the land for a few years for cattle farming so the destruction is harmful to the local economy

ii. draining wetlands

 * to make farmland or reduce breeding ground for malaria-carrying mosquitoes, //**90% of wetlands around Lake Ontario have been destroyed**//
 * problem: wetlands are good flood control, pollution removers and are home to many endangered plant and animal species

#2 Alien Species

 * humans introduce new species into regions that destroy habitat for native species
 * e.g. //**Zebra mussels**// (1980s) and //**Round Gobis**// (1990) in the Great Lakes
 * these aquatic (water) species entered the Great Lakes through ships' ballast water ([|Wikipedia Ballast Tank]).

#3 Over-exploitation

 * too much of a plant or animal population is used by humans
 * e.g. //**Atlantic cod**// (a type of fish)
 * in the 1950s 1000 tonnes were caught each year, by 2000 200 tonnes were being caught each year
 * e.g. //**Passenger pigeon**// ([[[]|Wikipedia Passenger Pigeon]])
 * went from hundred of millions, if not billions in 1850s to 0 in 1914. "Martha", the last known passenger pigeon, died in 1914 in a zoo.

#4 Disrupting connection in ecosystems

 * remove a food source and a predator suffers or remove a top-level predator and producers suffer

#5 Extinction

 * extinction reduces biodiversity when it happens (since an extinction removes a species from the ecosystem forever)

Task
Activity 3-1 on pg. 87 (done in class)