MAKING A MESOCOSM

Equipement

• A transparent, air-tight container (a glass jar with an air-tight lid is perfect, but an empty plastic water bottle is OK).
• Pebbles/gravel
• Soil/compost
• Seeds and/or plants
• Any optional extras you choose (e.g. old food to encourage bacteria growth, pond sludge etc.)

Instructions

Broadly, your task is to model a real ecosystem within the container. The system should have a water cycle, an exchange of minerals through growth and decay, as well as an exchange of carbon dioxide and oxygen through photosynthesis and respiration. The whole system will be driven by sunlight.

Plants will carry out both photosynthesis and respiration but other respiring (non-photosynthetic) organisms will also be needed. However, be mindful of animal rights - find ways to encourage microbial growth instead of using insects.

The following is a loose guide for setting up your system:

1. Put pebbles in the bottom of the jar (this provides drainage for water).
2. Add soil on top.
3. Add seeds or plants to the soil.
4. Water the system. Use enough for the plants, but do not waterlog the soil.
5. Add any optional extras that you think will contribute to the ecosystem.
6. Seal the lid (you might choose to leave it open for 1 or 2 weeks before sealing it).

Questions

1. After closing the lid, the mesocosm is (Change the colour of/highlight the correct answer):

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1. An open system
2. A closed system
3. An isolated system

2. Explain your answer to Q1.

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3. Evaluate the mesocosm as an ecosystem model.

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4. Draw a labeled diagram of your mesocosm. (You can draw on paper and upload a scan/photo)

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5. Draw a systems diagram of your mesocosm. (You can draw on paper and upload a scan/photo)

You will be marked for 1 mark each for:

• Storages
• Flows
• Input(s) and Output(s)
• Drawing standards

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