Barausse 4

Question 1

What is the ecosystem approach in marine conservation?

Answer 1

Question 2

Why has fisheries management shifted from single-species models to multiple-species and food web models?

Answer 2

Question 3

Why is it important to study species interactions and food webs in marine ecosystems?

Answer 3

Question 4

What is a trophic cascade, and how does it affect marine ecosystems?

Answer 4

Question 5

What is Ecopath, and what are its primary components?

Answer 5

Question 6

How is Ecopath used in sustainable fisheries management?

Answer 6

Question 7

What is a trophic network model, and how is it constructed?

Answer 7

• trophic network model represents the resource exchange
• Ecotrophic Efficiency (EE) is often a key component in constructing trophic network models, particularly in the Ecopath framework
• Ecotrophic Efficiency (EE) represents the fraction of a functional group’s production that is used within the ecosystem

Question 8

How is a fractional trophic level calculated, and why is it important?

Answer 8

Question 9

What is the principle of mass balance in ecological models?

Answer 9

Question 10

How is a mass-balanced model used in ecosystem analysis?

Answer 10

Question 11

What is ecotrophic efficiency (EE), and how is it estimated?

Answer 11

Low EE:

• Few Predators or Low Utilization: Suggests that the species or functional group is not heavily predated upon or utilized by the ecosystem.
• Potential for Biomass Accumulation: This might indicate that the species could accumulate biomass, possibly leading to an increase in population size if other conditions allow.

High EE:

• High Predator Dependence: Indicates that the species or functional group is highly predated upon or otherwise heavily utilized by the ecosystem.
• Ecological Importance: Suggests that the species plays a critical role in the food web, supporting many other species and contributing significantly to the ecosystem’s overall energy dynamics.

Question 12

Why is EE important in trophic network models?

Answer 12

Question 13

What is Ecosim, and how does it simulate trophic networks?

Answer 13

• Vulnerability values (v) in Ecosim determine how sensitive prey populations are to changes in predator populations
• Ecotrophic Efficiency (EE) is inherited from the static Ecopath model and represents the fraction of a functional group’s production that is utilized within the ecosystem

Question 14

How do vulnerabilities in Ecosim affect trophic interactions?

Answer 14

• Vulnerabilities help define how sensitive prey populations are to changes in predator populations and vice versa.
• represented by a parameter v that can range from 1 (low vulnerability) to values much greater than 1 (high vulnerability)
• Low Vulnerability (v close to 1): Bottom-Up Control
• High Vulnerability (v > 1): Top-Down Control