Lecture 25 (Energy Flow)

Question 1

Trophic dynamics?

Answer 1

energy transfer from one part of ecosystem to

another

Question 2

Why there are no ‘super predators’ that feed ontop

predators like wolves?

Answer 2

Energy losses limit number of trophic levels in
ecosystems. As energy moves from one organism some energy is lost as heat. (why second law of thermodynamics can’t go forever)

Question 3

-What are the two Laws of

Thermodynamics?

Answer 3

First Law of Thermodynamics:
The total amount of energy in the universe is
constant. Energy can be transformed, but not
created.

Second Law of Thermodynamics:
Heat energy will move from a warmer body to a
cooler one. Thus entropy will increase over time
in a closed system.

Question 4

-What is the 10% rule?

Answer 4

Only 10% of energy consumed by a trophic level is assimilated and available to higher trophic levels… this causes the trophic pyramid shape

Question 5

-What are Limits to Energy Transfer?

Answer 5

1. Energy losses limit number of trophic levels in
   ecosystems.
2. Can’t eat everything, and can’t find
   everything to eat (Not all biomass is edible and Not all biomass is accessible to be eaten)
3. High trophic level individuals occur
   at lower abundances than lower
   trophic levels (Super-predator is unlikely to
   evolve… because why would selection favour
   feeding on rare prey such as a wolf)

Question 6

When Energy Moves Between Aquatic

and Terrestrial Ecosystems (bear eats fish) is called?

Answer 6

Allochthonous inputs ( organic matter derives or
created in a community external to the one it is
deposited in)

Question 7

-What is a trophic cascade?

Answer 7

When a change in the population size of a species in one trophic level changes/alters populations in the
other trophic levels. (Increase in kelp results in an increase in herbivores that eat kelp, which results in an increased in predators that eat those herbivores… predation by otters maintain kelp forrest)

Question 8

Sea otter foraging?

Answer 8

find & collect shellfish
and crustaceans with
sensitive fore paws
and vibrissae
(whiskers)