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Reading Assignment: Chapter
38
Learning
Outcomes:
By the end of this lecture you should be able to explain:
- the various threats to biodiversity and the differences between the various
approaches to conservation biology
I. Threats to
Biodiversity:
There are four major threats to biodiversity:
1. Habitat destruction
2. Introduced species - species that humans remove from their native locations
to new geographic regions.
Problems with introduced species: transplanted species often explode to occupy a
new area. Examples: Nile perch (Lake
Victoria), Brown tree snake (Guam), the Zebra mussel (
U.S.
), the African honeybee (S. & N. America)
3. Overexploitation - consumption of wild plants and animals at rates that
exceed recovery rates.
4. Disruption of food chains - disruption of predator & prey and specialized
pollinator relationships.
II. Conservation
Biology:
Conservation biology goal: to counter the biodiversity crisis (rapid
decrease in variety of life on Earth).
There are two approaches to conservation biology:
1. Small population approach: understand what causes very small populations to
go extinct
Species must have a minimum viable population size (MVP) in order to avoid
extinction.
2. Declining-population approach: a decline in the # of individuals is a
concern, even if the total population # is greater than MVP
Edge habitats and movement corridors are important for species conservation.
Biodiversity hotspots: small areas w/ a large concentration
of endemic (native) & endangered species.
Restoration Ecology: uses ecological
principles to restore ecosystems; assumes most damage is reversible, but
communities aren’t infinitely resilient; the time it takes for an ecosystem to
recover depends on the spatial scale of the disturbance
“Deep
Trouble” Video Questions
1. How have fishing methods changed in the past 20 years?
2. What issue are biologists and fishermen in disagreement over?
3. What are the issues surrounding the Blue Fin tuna fishery and market?
4. How have fishing practices changed to deal with declining fish stocks?
5. What are the issues surrounding the Orange Roughy fishery?
6. How is deep sea fishing damaging deep sea habitats and affecting the
biodiversity of these communities?
7. What are the problems associated with fishing shallow water habitats for reef
fish?
8. Why is it a concern when a lot of juvenile fish are caught?
9. List the ways that shallow water fishing practices and other environmental
problems are harming coral reefs.
10. a) List the ways in which fishing nets cause problems for non-target
species.
10. b) What solution is being proposed to reduce the damaging effects of fishing
nets?
11. How/why is by-catch a problem? What
% of all fish caught is unwanted by-catch? How
much by-catch is caught for every pound of shrimp?
12. a) What are the advantages of aquaculture (fish-farming)?
12. b) What are the problems associated with aquaculture?
13. What are the issues surrounding the conservation of marine habitats?
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