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IB newsletter

Ecosystem in the bottle


Since October, window shields of one of the rooms have been crammed with bottles, jars, and other tightly sealed containers filled with rocks, soils, plants and, in some cases, also insects or snails – practically fully functional mini-ecosystems.

The project is one of the IB laboratory practicum called „Setting up sealed mesocosms to try to establish sustainability “. The aim of the project is to put into practice new knowledge learned during ecology classes by designing a fully functional, that is self-sustainable, ecosystem.

Mesocosm is a scientific term for enclosed environments that allow a small section of nature to be observed under controlled conditions. In our case, the experiment requests to have the container fully sealed.  This means that the ecosystems inside are isolated. In a similar way as the planet Earth, they receive light energy from sun but do not exchange any material resources with the outer environment.

Students had to put together a right combination of key ecosystem components which would provide all basic processes that cycle energy and nutrients and thus support life (photosynthesis, respiration, feeding, microbial decomposition of dead organic matter). Some of the ecosystems include also animals.

However, not to harm any organism, only small and more adaptable species such as snails, fruit flies or earthworms were considered. In some cases, these animals were not included on purpose, but they appeared during the experiment.

Students are using this temporary experimental space to explore different questions they have about the properties of ecosystems. Over the course of two months, they are making regular observations of the changes. Some students have planted seeds and observe if their ecosystem can support new life, while other evaluate qualitative changes, such as change in colour. Several students designed their ecosystem to evaluate limits of sustainability. For example, an aquatic ecosystem was filled with clean tap water to see how the plants will respond to the lack of nutrients and limited microbial activity.  Similarly, another experiment explores if one flowering plant can self-sustain itself as an ecosystem itself.

At the end of the term, the projects will result in informative lab reports where we can learn how these experiments turned out. However, if the mesocosms were well-designed, they can continue ad infinitum, similar to planetary ecosystem. Possibly the oldest permanently closed mesocosm is more than 50 years old. It was created by a curious gardener David Latimer who watered his sealed garden for the last time in 1972. Although some of the plants in his experiment died, one of them survived, and continues to thrive until today.

Agata Marzecova