Exploring Trophic Levels and Energy Flow in Ecosystems
Trophic Levels
Warm up
Define producers, consumers and decomposers.
Organisms that make their own food are
producers
.
Organisms that eat other organisms are called
consumers
.
Dead organisms are broken down and consumed by
microorganisms called
decomposers
.
Review
What is food?
Energy rich substances like starch and sugar.
Where is food made?
In producer organisms that engage in photosynthesis
like plants and algae.
Where is food used in the food web?
Every organism uses food including producers,
consumers and decomposers.
What is the point of consuming food?
To obtain the energy needed for life.
Mono Lake
Revisit your webs with your groups again.
Lay your cards out with producers at the bottom, the
primary consumers, etc.
Questions/Mono Lake
How does energy enter the Mono Lake ecosystem?
Sunlight captured by the algae during photosynthesis.
How else? (This one is tricky!)
Migratory birds.
Do migratory birds bring in energy or do they take it out?
They have more mass when they leave, so they take it out.
Algae manufacture food. What happens to the food made
by the algae?
Some is used by the algae, some by the primary consumers
that eat the algae, the rest is used by decomposers.
What happens to the energy eaten by the brine shrimp?
Some is used by the shrimp, some by the consumers that eat
them, some to decomposers. (Waste and dead shrimp.)
Trophic Levels
The levels in a food web are called
trophic levels
.
Energy enters the food web in the form of sugars and other
energy rich chemicals made by producers.
When primary consumers eat the producers the energy is
transferred to the next trophic level.
And so on……
The names we have been using for roles in the ecosystem
are the names of the trophic levels.
As you move from producers up through the consumers,
each trophic level gets farther away from the origional
source, which is usually light from the Sun.
Energy Levels
Look at your web.
Take a few minutes to trace the movement of energy
through the trophic levels in your web.
Energy should start at the Sun, transfer to food in one of
the producers, move from organism to organism through
the trophic levels and end up at decomposers where it
passes to the environment.
A short energy path might be: Sun- planktonic algae-
decomposer-environment.
A long path might be: Sun-benthic algae-brine fly-snowy
plover-California gull-coyote-decomposer-environment.
Energy Transfer Question
Is all the energy consumed by a primary consumer,
such as a brine shrimp, transferred to the secondary
consumer, like a gull, when the brine shrimp is eaten?
Example: A brine shrimp eats 10 g of algae in it’s life
before the gull eats it, does the gull get 10 g of food
energy when it eats the brine shrimp?
Discuss with a partner next to you.
Think of this question as we read
Tropic Levels.
Read
Page 20: Energy Transfer
What is the basic idea of this section?
Most of the energy that is consumed at one trophic level is
NOT incorporated into new biomass at that trophic level.
Most of the food consumed is used
by the organisms
to run
the machinery of life. Things like digesting food, moving,
pumping blood, producing offspring, etc….
Only about 10% of the energy consumed at a trophic level is
incorporated into the body tissue or offspring at the level.
Only 10% of the food energy consumed at one trophic
level is available for food for the next level
.
Write this information in your journal.
10% Idea
We have not considered this rule when looking at
Mono Lake.
Based on the 10% rule, could you have an ecosystem in
which there lived 100 kg of algae, 100 kg of brine
shrimp, and 100 kg of California gulls?
No
Make a Food Chain
In your journal, make one Mono Lake food chain, (not
the whole web) showing the use of food (energy) and
the production of biomass a each level.
Use the picture on page 19 as a model.
Biomass Models
I have cups with colored beads. Each bead represents
1 kg of biomass in Mono Lake. (One bead is not one
organism.)
Different colors represent different organisms.
We can use these beads to make a physical
representation of the trohpic levels in Mono Lake.
What Color?
Dark Green: Benthic algae
Light Green: Planktonic algae
Red: Brine shrimp
Black: Brine flies
Gray: California gulls
Try It
One red bead represents?
1 kg of brine shrimp.
What are brine shrimp going to eat?
Planktonic algae.
Using the 10% rule, you need to now put enough algae on
your pipe cleaner to feed your 1 kg of shrimp.
Lets see them? Did you get it right? How many beads did
you put on?
10!
That represents the 10 kg of algae biomass that your brine
shrimp consumed to produce your 1 kg brine shrimp biomass.
10%...remember?
Challenge
Construct 1 kg of gull biomass.
What do California gulls eat?
Brine shimp and brine flies.
Can you show how much biomass went into producing
a kg of California gull biomass with the beads in your
cup?
You will need to show not only the gull biomass, and the
food they eat (brine flies and shrimp) but the algae
(both kinds) the brine shrimp and flies eat as well.
Wrap Up:
Does a healthy ecosystem produce the same amount of
biomass at each level?
No
If the amount of biomass varies, which trophic level
has the most biomass? Why?
The greatest biomass has to be in the producers.
They are the foundation of the food web. The more
producers, the more primary consumers, etc.
Wrap Up:
If brine shrimp eat 10 kg of algae to produce 1 kg of
brine shrimp biomass, where does the other 9 kg of
biomass go?
Biomass is consumed for energy to run the processes of
life. 90% is converted into energy, simple chemicals
(carbon dioxide and water) and waste.
What happens to an ecosystem if one population fails?
Populations at trophic levels higher than the failure
might experience stress or failure due to lack of food.
Populations at lower trophic levels might thrive if there
are less predators.
Understanding trophic levels and energy flow in ecosystems is vital for comprehending the intricate relationships between producers, consumers, and decomposers. Energy enters the food web through producers, transferring from one trophic level to another. Explore the dynamics of Mono Lake ecosystem and trace the movement of energy through different organisms to decomposers and the environment.
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Presentation Transcript
Warm up Define producers, consumers and decomposers. Organisms that make their own food are producers. Organisms that eat other organisms are called consumers. Dead organisms are broken down and consumed by microorganisms called decomposers.
Review What is food? Energy rich substances like starch and sugar. Where is food made? In producer organisms that engage in photosynthesis like plants and algae. Where is food used in the food web? Every organism uses food including producers, consumers and decomposers. What is the point of consuming food? To obtain the energy needed for life.
Mono Lake Revisit your webs with your groups again. Lay your cards out with producers at the bottom, the primary consumers, etc.
Questions/Mono Lake How does energy enter the Mono Lake ecosystem? Sunlight captured by the algae during photosynthesis. How else? (This one is tricky!) Migratory birds. Do migratory birds bring in energy or do they take it out? They have more mass when they leave, so they take it out. Algae manufacture food. What happens to the food made by the algae? Some is used by the algae, some by the primary consumers that eat the algae, the rest is used by decomposers. What happens to the energy eaten by the brine shrimp? Some is used by the shrimp, some by the consumers that eat them, some to decomposers. (Waste and dead shrimp.)
Trophic Levels The levels in a food web are called trophic levels. Energy enters the food web in the form of sugars and other energy rich chemicals made by producers. When primary consumers eat the producers the energy is transferred to the next trophic level. And so on The names we have been using for roles in the ecosystem are the names of the trophic levels. As you move from producers up through the consumers, each trophic level gets farther away from the origional source, which is usually light from the Sun.
Energy Levels Look at your web. Take a few minutes to trace the movement of energy through the trophic levels in your web. Energy should start at the Sun, transfer to food in one of the producers, move from organism to organism through the trophic levels and end up at decomposers where it passes to the environment. A short energy path might be: Sun- planktonic algae- decomposer-environment. A long path might be: Sun-benthic algae-brine fly-snowy plover-California gull-coyote-decomposer-environment.
Energy Transfer Question Is all the energy consumed by a primary consumer, such as a brine shrimp, transferred to the secondary consumer, like a gull, when the brine shrimp is eaten? Example: A brine shrimp eats 10 g of algae in it s life before the gull eats it, does the gull get 10 g of food energy when it eats the brine shrimp? Discuss with a partner next to you. Think of this question as we read Tropic Levels.
Read Page 20: Energy Transfer What is the basic idea of this section? Most of the energy that is consumed at one trophic level is NOT incorporated into new biomass at that trophic level. Most of the food consumed is used by the organisms to run the machinery of life. Things like digesting food, moving, pumping blood, producing offspring, etc . Only about 10% of the energy consumed at a trophic level is incorporated into the body tissue or offspring at the level. Only 10% of the food energy consumed at one trophic level is available for food for the next level. Write this information in your journal.
10% Idea We have not considered this rule when looking at Mono Lake. Based on the 10% rule, could you have an ecosystem in which there lived 100 kg of algae, 100 kg of brine shrimp, and 100 kg of California gulls? No
Make a Food Chain In your journal, make one Mono Lake food chain, (not the whole web) showing the use of food (energy) and the production of biomass a each level. Use the picture on page 19 as a model.
Biomass Models I have cups with colored beads. Each bead represents 1 kg of biomass in Mono Lake. (One bead is not one organism.) Different colors represent different organisms. We can use these beads to make a physical representation of the trohpic levels in Mono Lake.
What Color? Dark Green: Benthic algae Light Green: Planktonicalgae Red: Brine shrimp Black: Brine flies Gray: California gulls
Try It One red bead represents? 1 kg of brine shrimp. What are brine shrimp going to eat? Planktonicalgae. Using the 10% rule, you need to now put enough algae on your pipe cleaner to feed your 1 kg of shrimp. Lets see them? Did you get it right? How many beads did you put on? 10! That represents the 10 kg of algae biomass that your brine shrimp consumed to produce your 1 kg brine shrimp biomass. 10%...remember?
Challenge Construct 1 kg of gull biomass. What do California gulls eat? Brine shimpand brine flies. Can you show how much biomass went into producing a kg of California gull biomass with the beads in your cup? You will need to show not only the gull biomass, and the food they eat (brine flies and shrimp) but the algae (both kinds) the brine shrimp and flies eat as well.
Wrap Up: Does a healthy ecosystem produce the same amount of biomass at each level? No If the amount of biomass varies, which trophic level has the most biomass? Why? The greatest biomass has to be in the producers. They are the foundation of the food web. The more producers, the more primary consumers, etc.
Wrap Up: If brine shrimp eat 10 kg of algae to produce 1 kg of brine shrimp biomass, where does the other 9 kg of biomass go? Biomass is consumed for energy to run the processes of life. 90% is converted into energy, simple chemicals (carbon dioxide and water) and waste. What happens to an ecosystem if one population fails? Populations at trophic levels higher than the failure might experience stress or failure due to lack of food. Populations at lower trophic levels might thrive if there are less predators.
