Food Web Dynamics and Ecosystem Impact

Professor Steve discusses trophic cascades, explaining how changes in one part of a food chain can affect other parts. Using the cod fishery as an example, he illustrates the impact of overfishing on ecosystems. The lecture also covers the complexity of food webs and how natural phenomena like climate patterns can cause similar effects. The importance of understanding these interactions is emphasized for better ecosystem management.

What is the primary concept discussed in the introduction of the lesson?

• Human impact on ecosystems

• Trophic cascades

• Climate change effects

• Food chain dynamics

In the cod fishery example, what happens when the cod population is overfished?

• The nutrient pool increases

• The prey population decreases

• The prey population increases

• The Z Plankton population grows

What term is used to describe the control of prey populations by predators?

• Equilibrium control

• Lateral control

• Top-down control

• Bottom-up control

How does the complexity of food webs affect the impact of changes in one species?

• It limits the impact to a single species

• It has no effect on other species

• It amplifies the impact across multiple species

• It only affects the species directly above in the food chain

What is a potential consequence of overfishing cod on sea lions?

• Increase in sea lion population

• Increase in sea lion prey

• No effect on sea lions

• Decrease in sea lion food sources

What happens to the sea otter population when orcas change their prey due to reduced sea lion availability?

• Sea otter population is unaffected

• Sea otter population decreases

• Sea otter population remains stable

• Sea otter population increases

What role do clams play in the ecosystem according to the case study?

• Consumers of large algae

• Filters of the water column

• Producers of nutrients

• Predators of sea urchins

What natural phenomena are discussed as having similar effects to overfishing?

• Tidal waves

• Earthquakes

• Ocean circulation patterns

• Volcanic eruptions

What is the significance of the El Nino years in the context of anchovy biomass?

• They decrease anchovy biomass

• They have no effect on anchovy biomass

• They increase anchovy biomass

• They cause anchovy extinction

What is the main challenge in understanding long-term climate patterns?

• Human interference

• Complexity and long-term nature

• Short-term variability

• Lack of data