Overexploitation - exam 2

Question 1

Define Tragedy of the Commons
Define Overexploitation and how our political/economic systems exacerbate it.
Where does overexploitation rank among threats to biodiversity?
Give 5 example species affected by overexploitation.

Answer 1

Question 2

Explain how/why species such as herons, pelicans, egrets, etc. were overharvested.
Who was mostly responsible for getting protections put in place for them? What did he do?

Answer 2

Pelican Island National Wildlife Refuge

Question 3

Describe 4-5 types of overexploitation that put pressure specifically on tropical forest ecosystems.

Answer 3

Question 4

Describe the level of threat posed by overexploitation on the world’s tree species.
What factors make certain trees more vulnerable?

Answer 4

Question 5

Describe 4-5 types of overexploitation that put pressure specifically on temperate forest ecosystems.

Answer 5

Question 6

Globally, what % of fish stocks are overexploited?
What 4 characteristics make some fish species particularly vulnerable?

Answer 6

Question 7

What is the range of cod?
Describe the overexploitation of this species and when it was at its worst.
Has there been any recovery?

Answer 7

Question 8

What act was passed in the US in 1976 to bring overfishing under control?
What regulatory agency is responsible for its enforcement?
What does the act do?

Answer 8

Question 9

About how old are sharks as a species group?
How many sharks are harvest each year, and why?
What percentage/how many shark species are on the IUCN Red List?
Describe 3 prominent measures taken to protect sharks.

Answer 9

Question 10

Describe how human hunting has affected the size of mammals across human history.

Answer 10

Question 11

Describe the overexploitation of elephants. Why does it happen? What dynamics are at play as they become more rare? How does it impact the ecosystem? What is an example of some recent protections?

Answer 11

Question 12

What is bushmeat?
Where is it a problem?
What are 4 catalysts that make the problem worse?
What markets does the practice supply?

Answer 12

Question 13

What’s the deal with Pangolins?

Answer 13

Question 14

What is a wet market and why is it a problem?

Answer 14

Question 15

What’s the deal with overexploitation of succulent plants?

Answer 15

Question 16

What is CITES?
What does it do?
When was it enacted?

Answer 16

Question 17

Describe at least 4 effects of overexploitation on non-target species/ecosystems.

Answer 17

Question 18

Can species be sustainably exploited?
Why/how?
What is a density dependent population growth pattern?
Describe what maximum sustainable yield of a species looks like and how it is implemented.

Answer 18

K = nmax = carrying capacity

Question 19

What are 8 general factors that make some species particularly vulnerable to overexploitation?

Answer 19

Question 20

Scientific papers:

Maigret et al:
* surface mining disproportionately affects ridgetop
* studied timber rattlesnake habitat to assess this habitat type in eastern KY

Myers et al:
* overexploitation has reduced apex predator (shark) populations
* elasmobranch (rays, skates, small sharks) populations have exploded as a result
* elasmobranch prey (bay scallops) have nearly been eliminated from the ecosystem and as an important commercial species

Terborgh et al:
* studied top-down ecosystem regulation by predators, thus limiting herbivore populations
* on small islands where predators of vertebrates are absent, densities of rodents, howler monkeys, iguanas, and leaf-cutter ants are 10-100x greater than on the mainland (which has predators)
* densities of seedlings and saplings are severely reduced on predator excluded islands by the increased densities of these herbivores

Walker et al:
* studied proportion of brazilian cattle industry that may be susceptible to market demands for deforestation-free supplies
* 40% of beef and 85% of leather production serves markets that express concerns about environmental impacts of their purchases
* however, about 25% of brazilian cattle slaughter occurs in the clandestine/black market, which is not susceptible to these market forces. better enforcement and regulation will be needed to tackle this problem.

Answer 20

Maigret et al:
* surface mining disproportionately affects ridgetop
* studied timber rattlesnake habitat to assess this habitat type in eastern KY

Myers et al:
* overexploitation has reduced apex predator (shark) populations
* elasmobranch (rays, skates, small sharks) populations have exploded as a result
* elasmobranch prey (bay scallops) have nearly been eliminated from the ecosystem and as an important commercial species

Terborgh et al:
* studied top-down ecosystem regulation by predators, thus limiting herbivore populations
* on small islands where predators of vertebrates are absent, densities of rodents, howler monkeys, iguanas, and leaf-cutter ants are 10-100x greater than on the mainland (which has predators)
* densities of seedlings and saplings are severely reduced on predator excluded islands by the increased densities of these herbivores

Walker et al:
* studied proportion of brazilian cattle industry that may be susceptible to market demands for deforestation-free supplies
* 40% of beef and 85% of leather production serves markets that express concerns about environmental impacts of their purchases
* however, about 25% of brazilian cattle slaughter occurs in the clandestine/black market, which is not susceptible to these market forces. better enforcement and regulation will be needed to tackle this problem.