ENV100Y5 Lecture Notes - Lecture 31: Cites, Reconciliation Ecology, Easter Island
Module 3: June 4-June 15
Date: Wednesday, June 13
SESSION 33: CONSERVATION OF SPECIES AND HABITATS (III)
Readings: Chapter 10
Red List Threatened Species
● February 2017: 87, 967 species assessed
● 25,062 are threatened with extinction ﹌29% (greater than 50% chance that they will
disappear in 10 years)
● Current Extinction rates: 100 - 1,000 X background levels
● In tropics: may be 10,000 X above background levels
● Is this the “6th” wave? We are in the 6th wave of mass extinction. We are the single
species responsible for mass extinction
Trends
● 30% of known species are under threat of extinction, but it isn’t accounting for rare
species, so the numbers are much higher
Causes of Biodiversity Loss
● Exploitation - directly, specifically target wildlife
● Habitat degradation and change
● Climate change
● Invasive species
● Pollution
● Disease
Exploitation
● E.g. trade in endangered species
● Only ‘50 years left’ for fish stocks
○ By-catch - when we kill things we don’t intend to kill (ex. Get caught in nets, bum
into boats, accidentally taking bait)
○ Overfishing disrupts food web
○ Problem is we are causing a collapse in ecosystem that support those stocks
● Loss of biodiversity is driving collapse of fisheries
Habitat Loss and Fragmentation
● Isolate patches, separate, make them small, you will drive biodiversity down
● Forests are home to 90% terrestrial species
● 80% of world’s forests are degraded or destroyed
Invasive Species
● Agriculture: losses of $55 - $250 billion annually
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ENV100Y5 Full Course Notes
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Document Summary
Session 33: conservation of species and habitats (iii) 25,062 are threatened with extinction 29% (greater than 50% chance that they will disappear in 10 years) Current extinction rates: 100 - 1,000 x background levels. In tropics: may be 10,000 x above background levels. We are in the 6th wave of mass extinction. We are the single species responsible for mass extinction. 30% of known species are under threat of extinction, but it isn"t accounting for rare species, so the numbers are much higher. Only 50 years left" for fish stocks. By-catch - when we kill things we don"t intend to kill (ex. Get caught in nets, bum into boats, accidentally taking bait) Problem is we are causing a collapse in ecosystem that support those stocks. Loss of biodiversity is driving collapse of fisheries. Isolate patches, separate, make them small, you will drive biodiversity down. Forests are home to 90% terrestrial species. 80% of world"s forests are degraded or destroyed.
