Extreme Environments

Prep time: 20 min to gather supplies

Class time: 90 min to design and set up experiments

Time for brine shrimp to hatch: 1–2 days

• Abiotic factors
• Brine shrimp life cycle

For the Class

• Student Pages
• 1 g brine shrimp cysts in salt solution

For Each Lab Group

• small Petri dishes
• soft, white, absorbent paper towels (uniform embossing works best)
• small pipet or dropper
• 10 mL of 3% salt solution
• microscope or hand lens

Optional Materials for Student–Designed Experiments

• Petri dishes or other shallow, wide containers, test tubes, graduated cylinders
• UV light source (UV light box or goggle sterilizer)
• incubator, refrigerator
• acidic and basic solutions (vinegar, bleach, etc.)
• aluminum foil
• non–iodized salt
• "pollutants" (household pesticide and herbicide, fertilizer, etc.)
• aquarium aerator, flexible tubing

Before doing the lab

• Order brine shrimp cysts (often referred to as brine shrimp eggs) from any biological supply company (see quantity at right). Cysts will come dried and will keep for years.
• Gather lab materials your students may use to conduct their experiments. Examples are included at right. See the table on page 7 in the Hatch–a–Cyst Teacher Guide for more information.
• One hour before the lab: Hydrate 1 g brine shrimp cysts in 500 mL of 3% salt solution.To make the salt solution, dissolve 15 g of Instant OceanTM or non–iodized salt (such as sea salt) in 500 mL of tap or deionized water. Prepare additional 3% salt solution as needed, enough to give 10 mL to each lab group.

Activity Instructions

1. Give each student or group of students a copy of the Hatch–a–Cyst Student Pages.
2. Use the worksheets as a scaffold for conducting this exercise. See the annotated Hatch–a–Cyst Teacher Guide document for suggestions, background information, tips and tricks.
3. Be sure that students or groups of students test a variety of individual abiotic factors in each class. Wrap up the activity by pooling the students' experimental results to determine the optimal environment in which to hatch brine shrimp.

Class time: 50 min

Time for brine shrimp to hatch: 2 days

• Brine shrimp life cycle

For Each Lab Group

• Student Pages
• 0.25 g brine shrimp cysts (available from a number of biological supply companies)
• 100 mL 3% salt solution (dissolve 3 g non-iodized salt such as sea salt or Instant OceanTM in 100 mL tap or deionized water)
• 100 mL or larger container for hatching the cysts
• aquarium pump and flexible tubing (optional)
• various materials to mimic environmental extremes

Before doing the lab

• Order brine shrimp cysts (often referred to as brine shrimp eggs) from any biological supply company (see quantity at right). Cysts will come dried and will keep for years.

Activity Instructions

1. Give each student the Abuse-A-Cyst Student Pages. Help students think of environmental extremes cysts at the Great Salt Lake are likely to encounter. Extreme environments that can be reproduced by students in the lab include:
• Extreme Heat - Bake the cysts in an oven, immerse them in boiling water.
• Extreme Cold — Use a freezer, dry ice, or liquid nitrogen.
• Dehydration — A food dehydrator on the "herb" setting works well.
• pH — Soak them in acidic or alkaline solutions (vinegar, lemon juice, baking soda etc.).
• UV radiation — Use a UV light box, or a goggle cabinet sterilizer.
• Wildfire — Soak the cysts in alcohol and light them on fire!
• Digestion — Mix cysts with pepsin and/or hydrochloric acid.
• Chemical/Toxin Exposure — Expose cysts to acetone, yard care chemicals, insecticides or auto care chemicals.
• Salinity — Mix a concentrated salt solution with non-iodized salt (calculate percentage salinity in grams per 100 mL)
2. Have students work in groups or individually to design and conduct their experiments. Provide salt solution and containers in which students can hatch their treated cysts. Aerating the hatching containers with an aquarium pump and flexible tubing is ideal, but brine shrimp cysts can still hatch without it.
Tip: If subjecting cysts to a chemical treatment, be sure students avoid contaminating the hatching environment by using water and a fine filter (such as a nylon stocking) to wash the treatment off of the cysts prior to placing them in the hatching containers.

There are varying degrees to which students may quantify their results. Examples include:

• Use general terms like "all", "none", "many", "most", or give rough percentages to describe how many cysts hatched.
• Quantify and hatch a small sample of cysts that have been exposed to the experimental treatment:
1. Hydrate cysts that have been exposed to the experimental treatment for one hour in a beaker of water. Fold a white absorbent paper towel to line the bottom of a petri dish.
2. Use a pipet to take a small sample of cysts from the bottom of the beaker.
3. Spread the sample evenly on the paper towel–lined Petri dish and place it under a microscope. Count the number of cysts.
4. Further saturate the paper towel with 3% salt solution.This will be enough water for hatching, but not enough for swimming. Cover the dish and keep it at room temperature.
5. In approximately 2 days, examine the dish under a microscope to count the number of hatched nauplii.

   Note: It is easier to subject a large number of cysts to the experimental treatment first, then hatch only a small sample. If students subject the cysts to a chemical treatment, be sure they rinse the cysts before hydrating them to avoid contaminating the hatching environment in the Petri dish.

Here are some points you can discuss with your students:

• Features of organisms that give them a survival advantage are called adaptations. In this case, the ability to lay resilient, dormant cysts is the adaptation that allows brine shrimp to survive the extreme conditions of the Great Salt Lake.
• Adaptations in organisms are not generated by the environment. Rather, organisms that possess an advantageous feature simply survive when put to the test while organisms without the feature perish.

Prep time: 20 min

To collect sediment and water samples: 1–3 hr

Class time: 60 min

10 minutes weekly, over several weeks to three months

• Abiotic factors
• Roles of microbes
• Requirements for life (ie, nutrients, light, oxygen, etc.)

• Microbiology
• Ecology

Potential extensions

• Nutrient cycling
• Metabolism
• Microscopy
• Natural selection and evolution

For the class

• water and sediment samples
• trowel, scoop, or shovel
• 2 buckets or other large containers

Optional

• nutrients
• measuring spoons
• lights, aluminum foil, refrigerator, etc. for varying incubation conditions

For each group

• copies of Student Pages
• clear plastic or glass containers
• lids, parafilm, or plastic wrap
• bucket, dish basin, or bowl
• ladle or large spoon
• funnel, if using narrow containers (or use the cut off top from a 2 L soda bottle)
• permanent markers
• gloves and safety goggles

• Grades 7–10

U.S. National Science Education Standards

Grades 6–8

• Content Standard C: Life Science—Populations and Ecosystems
  
  The number of organisms an ecosystem can support depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition. Given adequate biotic and abiotic resources and no disease or predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches

Grades 9–12

• Content Standard C: Life Science—Matter, Energy and Organization in Living Systems
  
  The distribution and abundance of organisms and populations in ecosystems are limited by the availability of matter and energy and the ability of the ecosystem to recycle materials.

AAAS Benchmarks for Science Literacy

Grades 6–8

• The Living Environment: Interdependence of Life
  
  The world contains a wide diversity of physical conditions, which creates a wide variety of environments: freshwater, marine, forest, desert, grassland, mountain, and others. In any particular environment, the growth and survival of organisms depend on the physical conditions. Given adequate resources and an absence of disease or predators, populations of organisms in ecosystems increase at rapid rates. Finite resources and other factors limit their growth.

You will need sediment and water samples from two different environments. For example, you can collect a fresh water and a salt water sample, or samples from Farmington Bay and Ogden Bay, on opposite sides of the Antelope Island causeway. The more different the environments, the more differences students will see in their Winogradsky columns.

Before doing the lab

• Gather materials (see right), including nutrients
• Make copies of student pages (download pdf file above).
• With your shovel and bucket, gather samples of sediment and water from two locations. You may wish to collect samples ahead of time, or you may choose to do so on a field trip to Great Salt Lake with your students (students may also build their columns at the lake).

Activity Instructions

1. Give each student or group of students a copy of the Student Pages.
2. Go over page 2 of the Student Pages with your students. Refer to the version with notes for teachers (download above) for suggestions, background information, and tips and tricks.
3. Help your students fill out on page 2 which nutrients (if any) they will add to their columns, and how they will incubate their columns. See Variations below for a few different options.
4. Have students follow the instructions on pages 3–4 of the student handout sheets to build their columns and find a place to incubate them.
5. Have your students observe their columns weekly. Make sure they record their observations.
6. After several weeks, have students report their observations to the class. Pool the data from all students or groups and discuss it together.
7. As your students report their observations, incorporate the discussion topics (see below) into your lesson.

We have tried to make the Student Pages flexible so you can do the activity in different ways, depending on what works best for you and your students. Here are some suggestions:

• Have each student or group of students make two columns, one for each location.
• Have half of your students or groups make columns from one location, while the other half makes columns from another location.
• Ask your students to deduce the effects of different nutrients and incubation conditions.
• If your students are more advanced, guide them in setting up their own experiments to test the effects of different nutrients and incubation conditions.
• If your students are less advanced or if you have less time, assign specific nutrients or incubation conditions to different students or groups of students. Discuss as a class.
• If you have limited time or supplies, you may choose to set up a small number of columns and have the whole class observe them together.

Here are some points you can discuss with your students (Example answers are in italics).

1. Where did the microbes come from?
   (They were already in the soil & water samples.)
2. What were the nutrients for? (To help the different types of microbes grow.)
3. What differences did you see in the columns from from the two different locations? Why do you think they are different?
   (They contained different types of microbes to start with, and the abiotic conditions were different.)
4. Do the abiotic factors vary within your column? How? How do you know?
   (Yes. You know because layers of different kinds of microbes formed in the columns. See the time lapse video for more information about how the layers differ.)
5. How did the abiotic factors (light, oxygen, nutrients, etc.) influence the types and amounts of microbes that grew?
   (See Table 1 and Table 2 for guidance.)
6. Organisms can change the abiotic factors in an environment. Which factors in your columns do you think the microbes changed? Do you think these microbes could survive without each other? What about other oganisms (plants, animals) in an ecosystem?
   (Photosynthetic microbes release oxygen, which is metabolized by aerobic microbes. *** more examples.)
7. What role do microbes play in an ecosystem?
   (Some decompose; some [especially photosynthetic] are producers—brine flies and brine shrimp eat them; important for nutrient cycles.)

If you do this lab as part of a field trip

• Have your students measure, record, and compare the abiotic conditions at the two sites: air and water temperature, water salinity, dissolved oxygen, pH, etc.
• Have your students use their senses (color, smell, etc.) to look for signs of microbes.

After the columns have incubated for at least four weeks, your students can begin removing samples and observing them under the microscope.

Ask your students to think about how human activity impacts microbes in an ecosystem. You could also have them design experiments to test the effects of different environmental contaminants.

Use this activity to build connections to other topics:

• Nutrient cycling (carbon, oxygen, sulfur, etc.)
• Metabolism (Winogradsky columns contain autotrophs, chemotrophs, phototrophs, heterotrophs)
• Natural selection