Ecosystem in a Bottle
Finding the Balance
Background
The ecosystem in a bottle experiment is the perfect setup to use to find out how nature manages to keep a balance. It will also show you how difficult it is to keep that balance and therefore how important it is to not upset ecosystems – which we human beings seem to do too often! Let's do science...
The Experiment
The Aim
To build an small ecosystem and discover how important “balance” is in an ecosystem. Equipment Needed 8 identical glass jars with lids (1 liter each).Masking tape / Prestik.10 ml syringe and needle.Purified water (you can boil water and let it cool).Freshwater snails and 8 freshwater plants (chat to your pet store to find out which plants and snails will be best for your experiment).Aquarium sand.8 thermometers.pH test kit.Dissolved oxygen test kit. Method Label your jars 1 to 8.Place 1 inch of aquarium sand into each jar.Fill each of the jars with purified water to 1 inch from the top.In jars 3,4,5 and 6 place two freshwater plants. Make sure they are planted firmly in the sand so that they do not come loose.In jars 5,6,7 and 8 place two freshwater snails.Place a thermometer into each jar so that you can easily read the temperature.Using the nail and hammer, punch small hole into the top of each lid.Block up the hole in the lid with masking tape or prestik. This is to make sure that no air can escape out of the jars.Screw the lids on to each jar tightly and seal them further by wrapping masking tape around the lid.There are two jars with non plants or snails (these are your controls), twp with just plants, two with plants and snails and two with just snails.Each day (for 14 days), at the same time, record the changes that you see in each of the jars. Record things such as color of the water, the health of the plants and snails, the clarity of the water. Create scales from 1-5 for each of these (e.g. for color you could have 1=chocolate brown, 2=light brown, 3=just turning brown, 4=just not clear, 5=clear).Also record the temperature of the water. Using the syringe, use the hole in the lid to take enough water out of the jars to measure the dissolved oxygen and pH using the kits. Make sure that you seal the hole again once you have taken the water out with the syringe. Results
You will find that the conditions change in the - ecosystem in a bottle - jars depending on what is in them. Questions such as - which jar supported life the longest? - what difference did plants have on the survival of the snail? - what difference did the presence of snails have on the survival of plants? etc. etc. are the type of questions that need to be asked. The Conclusion
You should find that a balanced ecosystem (even an ecosystem in a bottle) will support life longer and more efficiently than one that is not balanced. Do some research to find out why this is so.
For a simpler ecosystem in a bottle experiment, click here.
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