Outcome 3 – Ecology Unit
Laws of Conservation:
Law of Conservation of Matter:
In any ordinary physical or chemical change, matter is neither created nor destroyed, only transformed from one form to another
Law of Conservation of Energy:
In any ordinary physical or chemical change, energy is neither created nor destroyed, only transformed from one form to another.
(Also known as the 1st Law of Thermodynamics)
2nd Law of Thermodynamics: When energy is ____changed______from one form to another, …
“Nothing is ever 100% efficient”
The 2nd Law of Thermodynamics is due to
Entropy – the tendency toward randomness.
(Energy does not want to be contained.)
Flow of Energy through Ecosystems:
Food Chain = A simple diagram of one string of feeding relationships in an ecosystem, showing the direction of the transfer of energy in that system.
SUN Grass Rabbit Fox Wolf Bacteria
Nutrient-rich Soil
A food chain will always start with the sun’s energy flowing to the autotrophs (producers), then herbivores, then one or more carnivores. Decomposers will eventually consume all organisms.
Producers = Organisms that make their own food from inorganic molecules and energy.
· For example: Plants, blue green algae, phytoplankton
· Most accomplish energy building through ______photosynthesis______:
H2O + Sunlight + CO2 à Sugar + O2
Consumers = Organisms that cannot make own food.
· Obtain energy by eating other organisms through a process called ______Cellular__
______Respiration______:
Sugar + O2 à CO2 + H2O + ENERGY
• Decomposers = Bacteria and fungi that break down organic material
Decomposers are essential to ecosystem health because they recycle nutrients back for producers to reuse.
Food Web - a group of food chains showing all of the feeding relationships in an ecosystem.
Man Fox Wolf
Sheep
Rabbit Mice Deer
Bacteria
Grass Flowers Carrots
Nutrient-Rich Soil
Example Food Web Work:
Tips for Creating Food Webs – What do all food webs need?
· Original source of energy (This is usually the sun!)
· Producers
· Consumers
· Decomposers
· Soil (This is included to show where decomposers return nutrients to for recycling back into the ecosystem).
· Arrows – Arrows ALWAYS show how ENERGY flows (so they should begin with the source of the energy and end at the organism gaining the energy.)
Practice with a small one: In a meadow, rabbits and snails eat grasses to survive. Sometimes a fox catches the rabbit for a tasty meal. Birds also search for their food in the meadow and sometimes capture snails. Draw a food web indicating the relationships described. Make sure you include all the necessary information for a food web.
SUN Decomposers
Fox Birds
Rabbits snails
Grasses
Nutrient rich Soil
One more practice with the information presented differently: Draw a food web indicating these relationships. Include everything that is necessary!
Organism / Organism’s foodArctic Wolf / Seals
Krill / Diatoms
Polar Bear / Seals, Arctic Cod
Seal / Arctic Cod, Krill
Artic Wolf Polar Bear
SUN
Seals
Decomposers
Arctic Cod
Krill
Diatoms
Soil
Hoo Eats Who?
Purpose: To construct a food web using the relationships and pictures given.
Materials: Copy of animal figures sheet, tape or glue, scissors, colored pencils, large sheet of paper (could use the back of scratch paper)
Method:
1. Turn a large sheet of paper the long way. Draw grass, seeds, flowers and plants along the bottom.
2. Cut out the animal figures. Affix the owl to the top of your food web.
3. Arrange the other animals on the page with space left to draw arrows in between. Make sure that your herbivores (primary consumers) are pasted nearest the plants, seeds and flowers. Then, place the secondary consumers in the next “row” and so on until you reach the top of your food chain … your owl.
4. Draw arrows from each animal to the animal that eats it. Make sure that your arrows are indicating the direction of energy flow.
5. Also, make sure you draw in some decomposers and indicate that the decomposer will eventually decompose all organisms in order to start the process all over again.
6. You must also include the sun as the provider of all energy. Make sure there are arrows from the sun to the appropriate trophic level.
Data: (Use this to figure out Hoo eats Who)
Animal: / Food Source:Owl / Field mouse, vole, bird, shrew, mole, lizard, grasshopper, beetle, moth
Field mouse / Grass, seeds, grasshopper, beetle, moth
Vole / Plant roots, grass, seeds, grasshopper, beetle, moth
Bird / Seeds, grasshopper, beetle, moth
Shrew / Grasshopper, beetle, moth
Mole / Grasshopper, beetle, moth
Lizard / Flowers, seeds, grasshopper, beetle, moth
Grasshopper / Leaves, grass, seeds
Beetle / Leaves, flowers, seeds
Moth / Flowers
Decomposers / Eventually – all energy goes here
Conclusion: Add your name to your food web!
1. Draw a food chain from your food web. Label the parts of the food chain.
Sun à Grass à Grasshopper à shrew à owl à decomposers
soil
2. Convert your food chain into an energy pyramid. Label energy transfer, loss and relative biomass.
SUN Decomposers
Owl (1)
Shrew (10)
Grasshopper(100)
Grass (1000)
Biological Magnification:
Biological Magnification = build up of toxins within feeding relationships. The further to the top of the food chain an organism is, the larger the quantity of toxins is built up within their tissues.
Draw a diagram to help you remember/understand biological magnification:
Deadly Links:
Students will model grasshoppers, shrews and hawks to describe how food flows through the ecosystem.
Conclusion Questions:
1. How does this activity relate to how energy flows through an ecosystem?
As the toxins move up in the food chain, the amount of toxins continues to increase because the smaller organisms need to eat more of the plants to survive. The secondary consumer then needs to eat multiple primary consumers to get the energy it needs, therefore, building on the amount of toxins within its body. This is similar to the amount of energy needed (number or organisms) for the secondary consumer to survive. It is in reverse order though.
2. Explain two possible consequences of pesticides entering the food chain.
1 – kills other non-harmful organisms within the ecosystem
2 – contaminates our food and causes human illness due to its consumption
3. An ecologist studied the presence of a toxic chemical in a lake. She found the water had one molecule of the chemical for every billion molecules of water. This is called part per billion (1 ppb). The algae growing in that lake had one part per million (1 ppm) of the toxic chemical. Small animals, called zooplankton had 10 ppm. Small fish had 100 ppm. Large fish had 1000 ppm. How do you explain this increase in this toxic chemical to 1000 ppm for the large fish?
The larger fish needs to consume multiple organisms, all of which ate the multiple smaller organisms, who consumed plants that took in the toxins. Therefore, these toxins continue to increase until it reaches the top of the food chain.
Also, what is the name of this process?
Biological magnification/Biological accumulation
4. The ecologist (from the previous question) found that this chemical in the lake was a pesticide that had been sprayed on cropland 100 miles away from the lake. How did so much of it get into the lake?
Rain that falls in this area removes the pesticides off the plants and it runs off to local waterways. Ultimately, leading to the lake.
Trophic Level = a layer in the feeding relationship of an ecosystem, one link in the food chain/web
All producers are in the same trophic level, all primary consumers are in the same trophic level, and so on.
Biomass = total amount of organic material present in a trophic level.
(The more material = the more energy.)
Another way to look at trophic levels …
Ecological (or Energy) Pyramids:
A diagram that shows the relative amounts of energy/biomass in the different trophic levels. The lowest trophic levels are at the bottom of the pyramid.
Energy Pipeline
Class total / Round 2
Class total
Autotroph
Herbivore
Carnivore
Decomposer
Total Growth Chart
Analysis:
1. What are some of the ways energy is used at each trophic level?
2. Where did the plants acquire their energy? Why were there no limits on the amount of “calories’ given to them?
3. How are plants limited in the real world? (Give at least three things that limit plant growth.)
4. What would happen to the amount of energy needed for the entire system if the carnivore had been allowed to “grow” to full size?
5. Why are food chains typically less than 4 trophic levels in length?
6. Why are there more plants on earth than carnivores?
7. Could a lower trophic level pass all its calories directly to a higher level?
§ What would be the consequences for the organisms involved?
§ How might this impact human food supplies as our world population (of humans) keeps growing?
Practicing Drawing Ecological Pyramids:
Step 1: Draw a food web showing these relationships. Include all necessary parts:
Organism: Organism: / Food sources:Hawk / Rabbit, Squirrel, Mice, Cardinal
Squirrel / Nuts
Rabbit / Grass
Snake / Mice, Cardinal, Toad, Insects
Toad / Insects
Fox / Rabbit, Squirrel, Mice, Cardinal
SUN Decomposers
Fox Hawk Snake
Rabbit Squirrel Mice Cardinal Toad
Insects
Grasses Nuts
Soil
Step 2: Draw a single food chain from the web. Label the parts.
Sun à Grass à Rabbit à Fox à Decomposers
Producer Primary consumer Secondary consumer
Soil
Step 3: Draw an ecological/energy pyramid showing the food chain. Label energy transfer, energy loss and relative biomass.
SUN
Fox(10)
Rabbit (100)
Grass(1000)
Carrying Capacity = The maximum population a community can tolerate for extended periods of time. Usually determined by abiotic factors …
Abiotic Factors = non-living characteristics of the environment.
For example:
- Sunlight
- Moisture
- Space
- Pollution
- Landscape/Terrain
Limiting Factors = Anything that keeps a population from over-growing the resources available.
Ecological Relationships:
Biodiversity: the number of species in an ecosystem
Territory = space claimed by an individual organism
Ecological Equilibrium = state of “balance” in an ecosystem
Niche = Role of organism in the ecosystem (job)
• Niche Diversity = Number of niches in an ecosystem; often determined by abiotic factors
· A niche is the sum of all activities and relationships a species has while obtaining and using resources needed to survive and reproduce.
· Only 1 species can occupy a whole niche in an ecosystem at a time.
Types of Ecological Relationships:
Competition = When species or individuals “fight” for the same resources.
The “fight” may be ___indirect____ … the individuals may ___never_____ directly contact each other.
Two species with similar needs for the same limited resources cannot coexist.
Keystone Species = a species that causes a large increase in diversity of its habitat.
Losing a keystone species usually ___disrupts______many ecological relationships.
Herbivory = A primary consumer feeds on a producer.
Predation = A consumer feeds on another consumer.
Symbiosis = a long-term relationship where two species live closely together and at least one benefits directly from the relationship.
Types of Symbiosis:
Mutualism =• Both organisms benefit from the relationship.
• Win-Win situation! / Commensalism =
• One organism benefits, the other one is unaffected.
• Win-Neutral relationship / Parasitism =
• One organism benefits, the other one is harmed!
• Win-Lose relationship
• Parasites rarely kill their hosts…it would require them to get another one!
Define the following terms:
· Ecosystem— variety of organisms that live together within a given area
· Erosion— removal of top soil by water or wind
· Insecticide— a chemical applied to crops to kill insects
· Manager— someone who supervises over others on a project or in a job
· Niche— role an organism plays within an ecosystem
Procedure:
1. Each group will receive a copy of the Ecosystem map, a set of ecosystem cards, a set of critter cards and a set of critter tokens.
· Using the ecosystem cards, locate each of the ecosystems on the map.
· Where does the stream begin and end on the map? Trace its course.
· Where is the golf course in relationship to the stream?
· Where are the parking lots in relationship to the stream?
· Where is the park in relationship to the other areas of town? Who do you think visits the park?
· Where is the prairie ecosystem in relationship to houses?
· What areas or neighborhoods on the map are similar to where we live?
2. Hand out the critter cards to members in your group as if you were playing a card game. When you receive the set of critter cards, read the back of the cards silently to yourself and observe the illustrations on the cards. Keep the cards you were given.
3. Arrange the Critter tokens neatly around the edge of the map in any order. Your group should have at least three of each different critter token.