NGSS MS-LS2-3 (Students who can demonstrate an understanding of this concept can develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem)

Ecosystem in a Bottle: A closer look at ecosystems and nutrient cycles

Background

The earth is made up of countless ecosystems. Most simply stated, an ecosystem is the combination of the biotic and abiotic components in a given area. More specifically, ecosystems are all of the organisms in an area interacting with their physical and chemical surroundings. Depending on how you define them, ecosystems can be as small as a puddle that forms after a heavy rain or as large as the biosphere, which is the entire living world, reaching from the cavernous depths of the oceans to the upper limits of the atmosphere. The transformation and cycling of energy through the system along with the synthesis and degradation of materials are central to every ecosystem, and we will explore all of these concepts in this exercise.

Think of the things that make up your ecosystem and list them below.Answers will vary – you may choose to complete this portion as a class to get everyone involved in thinking about components of an ecosystem. Be sure that students are including examples of both living and non-living things in their answers.

If we are planning on building an ecosystem, it is important that we first consider the necessities for every ecosystem on earth.

Sunlight: This is probably the most important need for all living organisms, because it is the source of all energy and provides heat for plants and animals.

Air: Air is made up of several gases, some of the most important of which are nitrogen, oxygen, and carbon dioxide. Plants and certain microbes cannot survive without carbon dioxide and animals cannot live without oxygen. Nitrogen is vastly important to all living things because it is a major component of every strand of DNA.

Water: Water is important for the most basic building blocks of life – cells. Water is important to the function of all living cells and tissues. Water can also be a habitat for plants and animals.

Nutrients: Living things need energy in order to function, move, grow, and reproduce. Nutrients (and light!) are the sources of energy in every ecosystem.

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Temperature: Every living organism on land or in water lives and operates within a certain range of ideal temperatures. Increasing or decreasing the environment’s temperature can drastically change the inhabitants of an ecosystem.

Draw an ecosystem of your choice and label each of the main components from the list above. You may also choose to have your students label the flow of energy through their ecosystem, or have them show/label the connections between each of the biotic and abiotic components in their ecosystems

ActivityToday you will be building an ecosystem in its entirety. You will be able to observe how things cycle through your ecosystem and observe how life is able sustain itself when left completely alone.

Supplies

- 2 *or 3 (empty) clear 2-liter bottles *Use three bottles to end up with a larger aquatic zone – you’ll only use the middle portion of the bottle as an ‘extender’ to the lower bottle

- Scissors- Clear Packing Tape- Water prepped for an aquarium This water should be prepped according to the

needs of the fish you are using- Rubber Band

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- 4in square of netting (can be anything from nylon material to several layers of cheese cloth)

- Soil- Dead organic material (some plant litter)- Pebbles/Aquarium gravel- Grass seed (or seed from other small plants)- Aquatic plants (elodea, duckweed, or other aquatic plants commonly sold in pet

stores)- Small terrestrial organisms (a few pill bugs, earthworms, microarthropods)- Small aquatic organisms (1-2 very small fish and 1-2 small snails)

Prepare the bottle according to the diagram on the right:

- Remove the top portion of one of the bottles (right where the bottle curves inward at the neck) and discard the top.

- Remove the bottom portion of the second bottle (right where the bottle curves inward at the bottom) and keep for later use

- Remove the cap from the second bottle and affix the netting over the hole with a rubber band. Be sure the rubber band is secure so large materials from the top of the ecosystem do not fall into the bottom of the ecosystem.

- Take the bottom piece you removed from the second bottle and poke very small holes in it (concentrate these holes on the very bottom of the piece)

Begin setup of the ecosystem, modeling the setup after the diagram on the right:

- Add pebbles/gravel to the bottom of the aquatic portion of the ecosystem

- Plant the aquatic plants into the gravel- Fill the aquatic portion with the provided

water. Be sure to leave a space at the top for air

- Gently add the aquatic organisms to their new environment and allow them to adjust while you setup the rest of the ecosystem

- Add a small layer of gravel to the terrestrial portion of the ecosystem

- Cover the gravel with a layer of soil - Plant a few of the provided seeds into the

soil

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- Gently add the terrestrial organisms to the top portion of the ecosystem - Place the cover (i.e. the bottom section of the bottle with holes) over the terrestrial

portion of the ecosystem- While holding the terrestrial portion over an empty beaker, slowly pour some of the

provided water into the cover and let it drain into the terrestrial portion of the ecosystem, be sure to check that no soil is leaking through the netting and landing in the beaker (leakage of the soil into the aquatic portion can damage the ecosystem). Add enough water to ensure that the soil is moist enough for seed germination.

- Once you are sure the netting keeps all gravel from leaking down, place the terrestrial portion onto the aquatic portion of your ecosystem

- Place a strip of clear packing tape around the junction of the two portions of the ecosystem to secure them and prevent any leakage

- Poke a few small holes into the air space above the water in the aquatic portion of your ecosystem

- Place your ecosystem in an area where it will receive sunlight but not get too warm (if the bottles get too hot, the organisms will essentially end up getting cooked – be sure to test the area you plan to place the ecosystems before your students start the project)

Observations/Follow-up

Have your students observe and record notes about their ecosystems each day, be sure to point out when algae first appears and talk with them about this new source of nutrients in their ecosystems.

To test your students’ understanding of the flow of energy and cycling of matter through their ecosystems, consider assigning a short lab report or have them diagram the flow of energy and nutrient cycling on a labeled illustration of their ecosystem.

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