Lecture 8 Flashcards
1
Q
Top-down
A
- Predators or consumers control the trophic levels below them
- Predict negative correlations between adjacent trophic levels
2
Q
Bottom-up
A
- Nutrients or food resources control the trophic levels above them
- Predicts positive correlations between all trophic layers
3
Q
PEG models
A
- Combines BU and ID control
- Zooplankton anundence tracks algal resources at first but later algae controls them, leading to a clear water phase
4
Q
Trophic cascade
A
- When a top-down effect goes down more than one layer
- E.g., late 1990’s, orcas began preying on orcas. Kelp forests disappear from sea urchin overgrazing
5
Q
Evidence types
A
- Experiments - manipulate trophic levels in isolated habitats or mesocosms
- Field studies - observations
- Neutral experiments - take advantage of fish kills
6
Q
Predation effects
A
- Not just abundence
- Zooplankton community structure
- Prey behaviour
