32.3: Lab Report

Modeling a Food Web

1. Draw a food web.
   
   
   
   
   
   
   
   
   
   
   
2. What is the ultimate source of energy for your food web?
   
   
   
   
3. What happens to this energy as it moves through the food web? Where does it end up?
   
   
   
   
   

Nutrient Cycling in Ecosystems

1. In the space below, diagram the flow of water through the ecosystem around you.
   
   
   
   
   

What is the role of plants in the global cycling of water?

Mycorrhizal Networks

1. The fungus obtains its sugars from the living plant tissue. What terms could you apply to this organism?
   
2. The plant synthesizes its own sugars during photosynthesis. What terms could you apply to this organism?
   

Somewhat recently, a researcher named Suzanne Simard began tracking the exchange of nutrients through mycorrhizae. Not just from tree to fungus, but from tree to tree via connections to the same mycorrhizal partner. By providing certain trees with carbon dioxide containing a heavier isotope of carbon (C14), Dr. Simard could track the sugars formed from those heavy carbon atoms as they moved from tree to tree. What she found was that the connections extended beyond just one tree to another, but that almost all of the trees within her plot were connected through a network of different mycorrhizal fungi. Trees of different species and fungi of different species could exchange nutrients with each other. Further study revealed that the exchange was not limited to nutrients and water, but also included transfer of plant defense compounds that worked like raising an alarm, cuing the other plants to start producing defensive chemicals.

3. How might this information change the way we study ecosystems?
   
   
4. Sketch a few of the above ground plants that you can see (or imagine) and connect them below ground via a mycorrhizal network. Use arrows to indicate the flow of sugar through this network. Add in some disturbance that would set off a plant’s immune system (attack of the caterpillars, fungal infection, etc…) and depict the movement of the signal throughout the plant community.

5. Add a parasitic plant into your ecosystem above and use arrows to depict the movement of sugars.
6. Are these parasitic plants autotrophic or heterotrophic? How would you classify them, using ecology terminology? Explain your reasoning.

7. What is the difference between a community and an ecosystem?

Community Interactions

8. Is the relationship between the fig and the wasp a parasitism or mutualism? Explain your reasoning.

Contributors and Attributions

•  Maria Morrow (College of the Redwoods)

Ecosystem & Eutrophication - Silver Springs

Table 1: Colorimeter data of Daphnia feeding on Chorella
	Absorbance value
Before feeding (time zero)
After feeding (time 30 minutes)

Questions

1. How did the absorbance change from time 0 to time 30 minutes? Did the absorbance increase, decrease, or stay the same?
   
   
2. What does the absorbance value change tell you about the concentration of the Chorella? Did it increase, decrease, or stay the same?
   
   
3. What does the absorbance value chance tell you about the behavior of the Daphnia? Did they consume Chorella? How do you know?
   
   
4. In a real aquatic ecosystem, do you think zooplankton could decrease the impact of cultural eutrophication and algae blooms? Explain why or why not.
   
   

Part 2

Questions

Based on your findings with the model, answer the following questions:

1. What is the maximum number of producers the ecosystem can support before higher trophic levels begin to decline?
   
   
2. What happens to community respiration in the simulated algae bloom? Does it increase, decrease, or stay the same?
   
   
3. What happens to the decomposer population in the simulated algae bloom? Does it increase, decrease, or stay the same? Why?
   
   
4. Which group of carnivores (which trophic level) is more greatly impacted by the algae bloom? Why do you think this is the case?
   
   

Activity II

QUESTIONS

Based on your findings with the model, answer the following questions:

1. Is an elimination of bread feasible? Why or why not?
   
   
   
2. How would the system respond to increasing levels of tourism, assuming bread levels also increased? What trophic levels are most impacted by increased levels of bread?
   
   
   
3. What is the role of bread in the system, and how does its presence or absence impact the ecology of Silver Springs?
   
   
   
4. What would be your suggestion to the managing board of Silver Springs? Should they completely eliminate the tourists feeding the ducks? Why or why not?
   
   
   

---

LICENSES AND ATTRIBUTIONS

CC LICENSED CONTENT, ORIGINAL

• Biology 102 Labs. Authored by: Lynette Hauser. Provided by: Tidewater Community College. Located at: [www.tcc.edu]. License: CC BY: Attribution

CC LICENSED CONTENT, SHARED PREVIOUSLY

• Trophic Levels. Authored by: Thompsma. Located at:[commons.wikimedia.org]. License: CC BY-SA: Attribution-ShareAlike

PUBLIC DOMAIN CONTENT

• Silver Spring Model. Authored by: Sholto Maud. Provided by: Wikipedia. Located at: [commons.wikimedia.org]. License: Public Domain: No Known Copyright

Ecology Game:

Islands have always provided scientists unique locations to learn about the natural world. Many of Charles Darwin’s key observations that led to his understanding of natural selection came from species living on the many islands that make up the Galapagos archipelago. For example, Darwin observed different species of finches were found on different islands and that the shape of the finches’ beaks corresponded to the type of food they consumed. Further research on the finches of the Galapagos by Dr. Peter Grant and Dr. Rosemary Grant found that even within an island, changes in environmental conditions (i.e. drought, disease) could influence the adaptations observed in the finches.

Because islands are isolated from the mainland and each other by water and often long distances, they can be colonized by new species that have intentionally or unintentionally dispersed to an island. In biology, we call this the founder effect, which is when a new population is established. A founding population is often small and has a different allele frequency than the original population. It is important to remember that every species that finds itself in a new habitat may not be ideally suited for the environmental conditions. Is the habitat, food, climate appropriate for the new species needs? Is there competition for any of these resources with species already living on the island? Large islands that are close to the mainland tend to support more species than small islands that are far from the mainland. As we discuss in class, we know that no two species can occupy the same ecological niche—basically, two species cannot co-exist if they are competing for the same resource. While niches can overlap significantly between two species, they cannot be exactly alike. Any habitat has a limited number of species that can be supported by the available resources. We know that the most successful species are those with adaptations best suited to the environment in which they find themselves and those that can best utilize the available resources. These individuals are able to survive and reproduce on the island and a new population is established there. Occasionally, if there is a mismatch in the individual’s traits and the environment in which they are located or the environmental conditions change unfavorably the individual may no longer succeed in that environment. This can lead to local extinction which is also known as extirpation. An extirpated species can recolonize if environmental conditions become favorable.

Today, you will be playing the role of an individual of one of the six different species on an ancient continent to the East in a game we call the Ecology Game. The objective of the game is to cross the ocean, colonizing islands as you go. However, every species in the game has its own ecological needs and each island along the way has specific environmental conditions and the ability to support different numbers of species. If you are a successful colonizer, a population of your species will exist on the island even after you have moved on. Please note that in order to colonize and establish a new population in real life, you would need a sexually mature male and female or a pregnant female. However, in this game, we are simplifying this concept by using a model of a single individual. Every species will not be able to colonize every island successfully and you have to compete with the other species who are also trying to make it to the new continent. The islands are of varying sizes and successful colonization may cover a small area or a large area depending on the size of the island. The winner is determined by a combination of the order that you reach the new continent and the island area (not how many islands, but how much island space) you have successfully colonized. Remember to think strategically! The Ecology Game is not always about speed, but thinking about your species, its ecological niche, and what we know about colonization and adaptation. Just because you are the first species to reach the new continent that does not mean you win the game. Think of today like an ecological game of chess!

Set up (per group—groups should have no more than 6 students):

• 1 board map
• 2 six-sided dice
• 1 cup of 6 species sticks
• 4 bags of colored game pieces (if groups are larger than 4 and additional game pieces are required use coins or see Manal for additional colored pieces)
• 6 species cards
• 24 island cards
• Environmental factor cards

To Begin:

1. Each person in the group should draw a species stick out of the cup. You will play the role of an individual of this species for the entire game.
2. Read the associated species card. This will tell you about your ecological niche and any movement limitations you will have in the game.
3. Each player can place their colored game piece at any location on the mainland to start the game.
4. Roll the dice. The player with the highest roll will go first and play will move counterclockwise around the group.

To Play:

1. Player 1 will roll both die. The sum of the numbers shown on the roll indicates how many squares the player can move.

Note

You cannot move diagonally but you can move vertically and horizontally and you can move forwards or backwards. Some species have limitations on the maximum number of moves they can make. If your roll exceeds the maximum number of moves for your species, you must stop at your maximum number. Every species can stop in the ocean.

2. With each roll, player 1 will also draw an environmental factor card which may influence your movement along the way. This card may affect all players, a subset of players, or just the player drawing the card.

3. If you land on any part of an island, choose the island card and determine if your species can successfully colonize the island. If so, fill that player’s name/species name in the appropriate slot on the card (remember, some islands can only hold a few species) and place a colored game piece on the island to indicate that it has been colonized by you.