Marine Food Webs

Question 1

Primary producers

Answer 1

1st, autotroph

Question 2

Primary consumers

Answer 2

2nd, heterotroph

Question 3

Secondary consumer

Answer 3

3rd, heterotroph

Question 4

Tertiary consumer

Answer 4

4th, top predator

Question 5

Why only 4-5 levels in marine systems?

Answer 5

Eating is inefficient
Long food chains are unstable
Predator design is limited
Omnivory

Question 6

Importance of body size

Answer 6

Generally a good predictor of trophic level because Energetic demand of consumers increases with size, and marine primary consumers are very small and numerous
BUT
Some apes predators begin life as eggs/larvae and increase in size

Question 7

Why do marine systems generally have more complex food webs

Answer 7

Low levels of specialism.
Openness of marine systems.
Large size changes along a life history.
Long lifespans - ontogenetic shifts (change diet or habitat).

Question 8

ADV of Bottom up food web regulation

Answer 8

Resource availability drives food web stabiity
Eg more phytoplankton= more copepods, sandeels, seabird breading success

Question 9

ADV of top down control (food web regulation)

Answer 9

Driven by pred prey interactions
Important for ecosystem structure and function
Observation from human exploit show how precarious food webs are

Question 10

What is Trophic cascade

Answer 10

Ecological phenomenon triggered by the addition or removal of top predators and involving recipricol changes in the relative populations of predator and prey through a food change. Often results in dramatic changes in ecosystem structure and nutrient cycling

Question 11

What is Mesopredator release

Answer 11

Phenomenon in which populations of medium sized predators rapidly increase after the removal of predators.
Changes in apex predator abundance can have disproportionate effects.