Pop Bottle Ecosystem

Among my table group in MSED 251, we have created an ecosystem within 2 two-liter soda bottles.  I have learned through this project that this is a fantastic way to teach students, young and old, about the components of an ecosystem!

We designed out ecosystem like the ones shown above.  The bottle on the bottom has the top cut off, allowing another upside-down bottle to rest inside of it.  Our bottom bottle contains pebbles, well water, a few drops of pond water, a couple pinches of dirt, oxygenating water plants, and two snails.  The top (upside-down) bottle has a sponge stuffed into its neck.  The sponge holds a string that hangs down from the bottle, into the water, allowing the water to travel up to the second bottle.  This bottle is partially filled with dirt, inserted by cutting off its bottom.  Our dirt has three layers: the first layer is dug up from outside, the middle layer is potting soil containing nutrients, and the top layer is more natural dirt.  In our soils, we have a transplanted ivy plant, as well as beans and bird seed that we have planted.  The soil absorbs water through the string, which makes its way to the roots of the plants.

This project is relatively easy to replicate, and is a simple yet complex way to show students the components of an ecosystem.  This bottle ecosystem demonstrates many different biogeochemical cycles.  The water cycle is the easiest to see, but the carbon cycle, nitrogen cycle, phosphorus cycle, and oxygen cycle are all taking place as well.  Respiration and photosynthesis are taking place among the plants in this ecosystem, and respiration is also being conducted by the living animals, such as the snails and other small organisms from the pond water or living in the natural soil.  Competition takes place between the plants over nutrients, water, and space to grow.  Competition is also happening between living organisms in the water and soil. Trophic levels and pyramids are also displayed.  The snails will eat algae and other small organisms in the water, and soil organisms may either eat the plants, or aid in providing nutrients to them.  Anything that dies will decompose and add nutrients back to the system, and help the other living organisms thrive.  Students are able to see these interactions among the parts of an ecosystem, and the symbiosis necessary between organisms to keep an ecosystem healthy.  They can examine the abiotic and biotic components, and how they are each important and unique in their functions.