Marine Ecosystem Dynamics and Resilience

The lecture explores how marine ecosystems respond to human pressures, focusing on resilience, evolutionary adaptation, and alternative states. It discusses nutrient pollution and fisheries' impact, highlighting historical and modern examples. The importance of species and genetic diversity for resilience is emphasized, along with evolutionary adaptation to environmental changes. Management implications include enhancing biodiversity and considering genetic diversity in conservation efforts.

What is the term used to describe the ability of ecosystems to withstand human pressures?

• Sustainability

• Adaptation

• Resistance

• Resilience

Why is nutrient pollution a significant problem for marine ecosystems?

• It increases the salinity of the water.

• It leads to the overgrowth of weedy algae.

• It causes water temperature to rise.

• It reduces the oxygen levels in the water.

What role do small grazers play in marine ecosystems affected by nutrient pollution?

• They increase the nutrient levels.

• They help maintain macrophyte beds.

• They decrease water temperature.

• They promote the growth of weedy algae.

What was the impact of overfishing on the Scotian shelf?

• Increased biodiversity

• Stabilized fish populations

• Near ecological extinction of cod

• Improved water quality

What is a self-reinforcing cycle in the context of marine ecosystems?

• A cycle that reduces nutrient pollution

• A cycle that increases species diversity

• A cycle that maintains a new ecosystem state

• A cycle that restores the original ecosystem state

What triggers the shift between kelp forests and sea urchin barrens?

• Decrease in fish populations

• Increase in nutrient pollution

• Presence of sea otters

• Changes in water temperature

What is the significance of thresholds in biological systems?

• They allow gradual changes in the ecosystem.

• They prevent any changes in the ecosystem.

• They cause rapid shifts to different ecosystem states.

• They stabilize the current ecosystem state.

How does species diversity contribute to ecosystem resilience?

• By reducing genetic diversity

• By increasing nutrient pollution

• By enhancing stability and productivity

• By promoting overfishing

What was the outcome of experiments on genetic diversity in sea grass beds?

• Decreased productivity and stability

• No significant change observed

• Increased vulnerability to stress

• Higher productivity and stability

What management strategy is suggested for maintaining ecosystem stability?

• Enhancing genetic diversity

• Promoting overfishing

• Reducing species diversity

• Increasing nutrient pollution