Download Energy Transfer

Energy Flow
PAGES 366-369
Energy Flow in an Ecosystem
Sun 
autotrophs
 heterotrophs
producers
consumers
Producers/Autotrophs
•Can make their own food through photosynthesis or
chemosynthesis
Productivity
•Productivity: energy made by producers (after biological
processes) available to consumers
•Gross primary productivity (GPP): rate at which producers
capture energy in organic compounds
Productivity
•Net primary productivity (NPP): the rate at which biomass
accumulates (after some is used)
•NPP= GPP – Cellular Respiration
Productivity
•Biomass: the amount of organic (living) material produced
Consumers
•Get energy by eating other organisms
•There are 5 types
Consumers
•Herbivores: eat producers
Consumers
•Carnivores: eat other consumers
Consumers
•Omnivores: eat producers and consumers
Consumers
•Detritivores: feed on “garbage” or dead organic matter (ex.
worms, millipedes, vultures)
Consumers
•Decomposer: break down dead organic matter into simpler
molecules (fungi and bacteria)
•Recycle nutrients back into ecosystem
Food Chain
•Food chain: a single pathway of feeding relationships in an
ecosystem that traces the transfer of energy
Food Web
•Interconnected food
chains
•Arrows show
transfer of energy
Tropic Level
•Trophic level: position in a series of energy transfers
Energy flows through ecosystems
sun
secondary
consumers
(carnivores)
primary consumers
(herbivores)
producers (plants)
loss of
energy
loss of
energy
Trophic Levels
•Only 10% of the total energy is passed onto the next trophic
level (rule of 10%)
◦Energy lost to biological processes (digestion, growth
and repair, running, walking etc.)
◦Energy lost as heat
90 % Energy
Lost
90 % Energy
Lost
90 % Energy
Lost
Large
Carnivore
• 3˚ Consumer
• Ex: killer whale
Small
Carnivore
• 2˚Consumer
• Ex: sea otter
Herbivore
• 1˚
Consumer
• Ex: sea
urchin
Producer
• Ex:
Kelp
Question: Why is a pyramid used to
display energy transfer and not a square?
Approximately 90%
loss of energy at each
trophic level
Keystone Species
•Has disproportionately large effect on the ecosystem
•Dictates community structure
•Demonstrated by removal of keystone species from
community
• Ex. Sea stars, otters
Sea star feeds on all
bivalves. When the
sea star is removed
from the tide pools
one bivalve (mussel)
out competes the rest
for resources and
becomes the dominant
species.