Step 1: Look at a Visual Example

Question

You’ll be choosing your own marine species in just a moment, but for now, take a look at this example:

Krill at the center of a food web; around it are a squid at the top, a seagull, a whale, plankton at the bottom, a penguin, and a seal. From the krill, arrows point to the seal, squid, seagull, and whale; plankton at the bottom of the web has arrows pointing to krill and the penguin; the penguin has an arrow pointing to the seal; the squid appear at the top of the web has arrows pointing to the seal, seagull, and penguin.
This example of an aquatic food web focuses on krill as the marine species at the center.
Notice the plankton (producer) and the krill (primary food source/consumer) as well as the penguin, seal, squid, seagull, and whale (higher-order consumers). What’s missing here? That’s right—decomposers! Bacteria happen to be the most common decomposers in marine environments. We can imagine that if they were portrayed on this food web, we’d see arrows connecting them to each organism.

Step 2: Choose a Marine Organism and Food Web
Now, it’s your turn! Think of a marine organism you’d like to learn a little more about that can serve as a primary food source in your food web.

Next, identify the other participants in the food web:

Producers: These will likely be plankton, but do some research on your marine organism to be sure.
Consumers: The primary consumer will be the organism you chose as the primary food source. Identify at least TWO other consumers that would eat the organism you chose.
Decomposers: These will likely be bacteria, but do some research on your marine organism to find out what kinds of decomposers would be in its food web.
Step 3: Draw Your Food Web
In order to organize your thoughts for the remaining parts of the activity, create a food web illustration like the one in Step 1 that includes the organisms you chose. You may choose to create your food web using word processing software, graphic design software, or art supplies.

Step 4: Find or Create Some Sample Data
Now, imagine that you are conducting a short-term study to analyze the interrelationships among the organism you chose (the primary consumer) and the producers, other consumers, and decomposers in the aquatic ecosystem in which your organism lives.

Imagine that your research is complete, and think about the presentation of your data that tracks the fluctuation of your chosen organism’s population over time. Remember that the data you “collect” will be a count of your chosen organism’s population in a certain ecosystem over a given short time frame (a few months to a year).

Will the population increase in the summer or decrease over the course of a year, for example? You may make up the data here or find actual data online.

If you do decide to look for actual population data, keep in mind that you will be synthesizing information from a range of sources. For example, if we stick with our sample krill organism, you might find one source that only tells you that the krill population decreases in the winter. Then, you might find another source that tells you by how much the population decreases.

As you look at different sources, you’ll have to synthesize comments, claims, and evidence made on all sides of the issue; resolve contradictions when possible; and determine what additional information or research is required to deepen the investigation or complete the task. You can do this by keeping notes on what each source says. Maybe you add in the information from each new source in a new color so that you will always know what information comes from which source. If there are discrepancies you cannot resolve yourself, use your best judgement, or ask your teacher for help.

Whether you create the sample data or find real data online, make sure your data includes these details:

The time frame in which you “collected” data (e.g., once a month for a year, twice a week for three months, etc.)
The population counts at each point that you counted (or found real data for)
Step 5: Generate a Table
Next, using word processing software, generate a table of population data for your chosen marine species.

Your table might look something like this:

Sample Data Table
Winter Spring Summer Fall
Krill Population 20 30 42 35
See that our krill population was 20 in the winter, 30 in the spring, 42 in the summer, and 35 in the fall.

Step 6: Reflect on the Data
Use your data to reflect on the following questions:

Question 1
Describe the data. Do you see any patterns or trends?

Question 2
Analyze the patterns or trends. Are there any patterns you see that relate to any other information you already know?

Question 3
Describe what you predict will happen to interspecific competition in the aquatic environment if populations of your chosen organism decline.

Question 4
Analyze and discuss how human activities such as fishing, transportation, dam-building, and recreation may influence the aquatic environment around your food web.

Question 5
What effects of chemical, organic, physical, and thermal changes could you predict these human activities might have on the living and nonliving components of your aquatic ecosystem?

Question 6
What effect do you think laws and policies such as the Endangered Species Act, right of capture laws, and the Clean Water Act might have on the organisms in your food web? How might their effects change the population data in your table?

Step 7: What to Submit
When you are happy with your work, submit these items:

Your food web (Step 3)
Your data table (Step 5)
Your answers to the reflection questions (Step 6)

Answer 1

Step 1: Visual Example

As specified in your example, krill is at the center of the food web with various consumers and producers connected to it.

Step 2: Choose a Marine Organism and Food Web

Chosen Marine Organism: Zooplankton (as the primary food source)

Producers:

1. Phytoplankton (microscopic plants that use sunlight for photosynthesis)

Consumers:

1. Zooplankton (primary consumer)
2. Small Fish (such as herring) (secondary consumer)
3. Mackerels (higher-order consumer, feed on small fish)

Decomposers:

• Bacteria and fungi (decompose organic matter from dead organisms)

Step 3: Draw Your Food Web

Here's how you can visualize the food web:

         Phytoplankton
           ↑
 Zooplankton ← Small Fish → Mackerel
           ↓
        Bacteria/Fungi

Step 4: Find or Create Sample Data

Imagine that we are researching the zooplankton population in a coastal ecosystem over a year, counting them monthly.

Sample Data:

• Time Frame: Once a month for one year
• Population Counts:
  • January: 50
  • February: 40
  • March: 60
  • April: 80
  • May: 90
  • June: 120
  • July: 130
  • August: 100
  • September: 70
  • October: 50
  • November: 40
  • December: 30

Step 5: Generate a Table

Here’s the population data table of zooplankton:

| Month | Zooplankton Population | |----------|------------------------| | January | 50 | | February | 40 | | March | 60 | | April | 80 | | May | 90 | | June | 120 | | July | 130 | | August | 100 | | September| 70 | | October | 50 | | November | 40 | | December | 30 |

Step 6: Reflect on the Data

Question 1:
The data shows that the zooplankton population increases significantly during the spring and summer months, reaching a peak in July at 130 individuals. A decline occurs in the fall and winter months.

Question 2:
The increase in zooplankton population correlates with warmer temperatures and an abundance of phytoplankton availability during spring and summer, essential for zooplankton’s growth, while a decline in fall and winter months aligns with cooler waters and reduced production.

Question 3:
If the zooplankton population declines, there would be increased interspecific competition among higher-order consumers (like small fish and mackerels) competing for fewer food resources, leading potentially to declining fish populations as well.

Question 4:
Human activities such as overfishing may deplete fish populations that rely on zooplankton. Dam-building impacts the flow of rivers, altering habitats and water quality. Recreational activities can lead to pollution and disturbances, affecting the health of zooplankton and phytoplankton populations.

Question 5:
Chemical changes (e.g., runoff fertilizers) can cause algal blooms that may suffocate zooplankton. Organic changes (introduction of new species) may disrupt food webs. Physical changes (construction or pollution) can harm habitats. Thermal changes (climate change) can alter reproduction rates and ecosystems.

Question 6:
Laws like the Endangered Species Act may protect species reliant on a healthy zooplankton population. The Clean Water Act aims to reduce pollution, which, if enforced, could enhance zooplankton populations. These policies could stabilize the numbers seen in my data table, potentially increasing populations if the environment improves.

Step 7: What to Submit

• Your food web illustration (Step 3)
• Your data table (Step 5)
• Answers to the reflection questions (Step 6)

Feel free to format or further enhance this information as needed!