Lecture 32: Synergies

Question 1

Why do small populations go extinct easier?

Answer 1

Demographic instability and inbreeding cause population decline (and eventually extinction)

Question 2

What is synergy?

Answer 2

An interactive effect that is greater than the sum of the individual effects

Question 3

What are the characteristics of synergies?

Answer 3

• occur when stresses overlap
• often unpredictable
• cause sudden disruptions or abrupt shifts
• nonlinear behaviour (cascading effects)

Question 4

How can land use and biological invasion cause synergy to alter ecosystem functioning?

Answer 4

Woody vegetation burns in forest fires, causing grasslands to take over, but if these grasses are invasive, the risk of forest fire increases causing microclimate issues.

Question 5

How can CO2 emissions and biological invasion cause synergy to alter ecosystem interactions?

Answer 5

CO2 emissions increase ocean acidification which reduces shell thickness of molluscs, making them more susceptible to predation. Given invasive snails, they becomes even more susceptible.

Question 6

What causes cholera outbreak?

Answer 6

Synergy between water contamination and international travel:
domestic sewage water causes plankton population explosion (which now contain cholera bacteria). The plankton are transported internationally in ballast water, causing an epidemic.

Question 7

How do nitrogen pollution and overfishing affect coral reefs?

Answer 7

removal of herbivores by overfishing and agriculture/sewage runoff causes increased algal bloom which cover coral reefs

Question 8

How do synergies occur and what do they demonstrate in terms of ecological problem solving?

Answer 8

result from connectedness of environmental systems and show that problems cannot be solved in isolation (must use a system-level approach)