Trophic Levels

1
Trophic Levels
2
Trophic Levels and Food Chains
Quaternary consumers

• Food Chain
• set of food (energy) transfer from trophic level
  to trophic level

Carnivore
Carnivore
Tertiary consumers
Carnivore
Carnivore
Secondary consumers
Carnivore
Carnivore
Primary consumers
Zooplankton
Herbivore
Producers
Plant
Phytoplankton
Figure 19.21
A terrestrial food chain
A marine food chain
3

• Herbivores eat plants, algae, or autotrophic
  bacteria, are the primary consumers of an
  ecosystem

• Carnivores, which eat the consumers from the
  levels below
• Secondary consumers include many small mammals,
  such as rodents, and small fishes that eat
  zooplankton
• Tertiary consumers, such as snakes, eat mice and
  other secondary consumers
• Quaternary consumers include hawks and killer
  whales.

4

• Decomposers

• What is a decomposer and what do they do? What
  trophic level would you put them at?
• Derive their energy from the dead material left
  by all trophic levels
• Are often left off of most food chain diagrams

Figure 19.22
5
Food Web Activity

• The feeding relationships in an ecosystem

• With your group list 12 organisms that live in
  one habitat. Include at least one from each
  trophic level. Show who eats who?
• What does it look like?
• List 6 abiotic factors that are part of your
  ecosystem? How do they affect organisms in the
  ecosystem?

6
Quaternary,
tertiary,
and secondary consumers
Tertiary and
secondary consumers
Secondary and
primary consumers
Primary consumers
Producers (plants)
Figure 19.23
7
What happens to energy as you go up trophic
levels? Why?
Tertiary consumers
10 kcal
Secondary consumers
100 kcal
Primary consumers
1,000 kcal
Producers
10,000 kcal
Figure 19.26
8
CHEMICAL CYCLING IN ECOSYSTEMS

• Ecosystems

• Depend on a recycling of chemical elements
• What gets recycled in our ecosystem?
• Energy?? NOOO
• Water
• Carbon
• Nitrogen

9

• Generalized scheme for biogeochemical cycles

Consumers
Producers
Detritivores
Nutrients available to producers
Abiotic reservoir
Geologic processes
Figure 19.28
10
CO2 in atmosphere
Photosynthesis
Burning

• The carbon cycle

Producers
Wood and fossil fuels
Cellular respiration
Higher-level consumers
Primary consumers
Decomposition
Detritivores
Detritus
What do we eat that has carbon?
(a) The carbon cycle
Figure 19.29a
11
Carbon Cycle

• Producers Plants take in CO2 and make sugar by
  photosynthesis.
• Consumers Animals eat plants to get energy
  (respiration) from sugar and make proteins from
  the carbon.
• Breath out CO2 as a waste product of respiration.
• Animals die and dentritus (decomposers) break
  down the carbon and other elements back into the
  soil and air for plants to use again.

12
Nitrogen (N2) in atmosphere

• The nitrogen cycle

Detritus
Amino acids and proteins in plants and animals
Detritivores
Denitrifying bacteria
Assimilation by plants
Nitrogen-fixing bacteria in root nodules of
legumes
Decomposition
Nitrates (NO3 )
Nitrogen fixation
Nitrogen-fixing bacteria in soil
Ammonium (NH4 )
Nitrifying bacteria
(b) The nitrogen cycle
Figure 19.29b
13
Nitrogen Fixation by bacteria

• Plants need nitrogen but cannot take it in from
  the air.
• Bacteria in the soil on the roots of plants take
  in nitrogen (N2) and make ammonia (NH4) which
  plants can then use to get nitrogen.

14
Net movement of water vapor by wind (36)
Solar heat
Water vapor over the land
Water vapor over the sea

• The water cycle

Precipitation over the land (95)
Evaporation and transpiration (59)
Precipitation over the sea (283)
Evaporation from the sea (319)
Surface water and groundwater
Flow of water from land to sea (36)
Oceans
(d) The water cycle
Figure 19.29d