Ethics
IB Ethical Guidelines
"The policy is based upon the established 3Rs principle (replacement, refinement and reduction), in which any experimentation involving animals should initially consider: replacement of the animals by using cells, plants or computer simulations; refinement to the experiment to alleviate any harm or distress to the animal; and reduction in the numbers of animals involved.
Ethical considerations in my experiment
As I have chosen to use only plants in my mesocosm, I have avoided many of the ethical guidelines regarding animals. However there is the possibility of insects present in the soil, and these may have died if the conditions were not suitable for them. The main ethical consideration involved with my experiment is the disposal of my mesocosm - I must ensure that no introduced species are released. All of the materials used in my mesocosm were already naturally occurring or growing in my garden.
"The policy is based upon the established 3Rs principle (replacement, refinement and reduction), in which any experimentation involving animals should initially consider: replacement of the animals by using cells, plants or computer simulations; refinement to the experiment to alleviate any harm or distress to the animal; and reduction in the numbers of animals involved.
- Any planned and actual experimentation involving animals must be subject to approval following a discussion between teacher and candidate(s) based on the IB animal experimentation policy.
- Experiments involving animals must be based on observing and measuring aspects of natural animal behaviour. Any experimentation should not result in any pain or undue stress on any animal (vertebrate or invertebrate) or compromise its health in any way. Therefore experiments that administer drugs or medicines or manipulate the environment or diet beyond that easily tolerated by the animal are unacceptable. Experiments resulting in the death of any animal are unacceptable.
- Any experimentation involving humans must be with their written permission and must follow the above guidelines. Experiments involving body fluids must not be performed due to the risk of the transmission of blood-borne pathogens."
Ethical considerations in my experiment
As I have chosen to use only plants in my mesocosm, I have avoided many of the ethical guidelines regarding animals. However there is the possibility of insects present in the soil, and these may have died if the conditions were not suitable for them. The main ethical consideration involved with my experiment is the disposal of my mesocosm - I must ensure that no introduced species are released. All of the materials used in my mesocosm were already naturally occurring or growing in my garden.
Data and results
Qualitative data
My main sources of qualitative data are the photos below, which track the progress of my mesocosm, as well as my weekly observations (/my-mesocosm.html) . The photos clearly show the gradual deterioration of the fern in particular. By week 2 the top leaves are brown, and by week 4 the plant is limp and leaning against the walls of the jar. Although not fully demonstrated in the photos, I can also see the gradual accumulation of water at the bottom of the jar, which represents the rising humidity - a possible factor to the death of the fern. Lastly, the photos show the spread of the moss and native violets, proving that growth did occur.
Quantitative data
My data shows a definite increase in all four areas of measurement: temperature, humidity, growth of moss and level of condensation. Although humidity dropped slightly in week 3, the graph is still clearly increasing. This allows me to identify a trend between humidity and condensation: as the level of humidity increased, so did the level of condensation. Therefore, the mesocosm became not only warmer, but also moister over the four weeks. These conditions are a likely cause of the death of the fern. My initial research showed that moss is suitable in a warm, moist environment, and this explains why it successfully spread over the surface area of the soil.
The temperature of the mesocosm significantly rose from 20.6 degrees Celsius to 24 degrees. This is due to the positioning of the mesocosm in a sunny location, as well as the natural process of plant respiration. The rising temperature mostly correlates with the humidity level, showing that as conditions become warmer, they also become wetter.
The temperature of the mesocosm significantly rose from 20.6 degrees Celsius to 24 degrees. This is due to the positioning of the mesocosm in a sunny location, as well as the natural process of plant respiration. The rising temperature mostly correlates with the humidity level, showing that as conditions become warmer, they also become wetter.
Discussion
My collection of data involved accurate measurement of temperature and humidity, however the measurement of the diameter of the moss is not entirely reliable, as the shape is not a perfect circle. The level of condensation was mostly an estimate, as there is no other way (in my non-laboratory circumstances) to measure condensation other than by observation. The majority of my results can be concluded from quantitative data, mostly observation, as this allows me to deduce which plants thrived in the environment, and which did not.
The most significant weakness of my experiment was the lack of control in regards to my materials. I collected the soil from my garden, meaning it could contain unknown bacteria and insects. These factors may have affected my experiment although I was unaware of the cause-effect relationship. Also, the plants in my mesocosm were simply from my garden, and this raises similar issues in the accuracy and reliability of my results.
Another weakness in the accuracy of my data is the fact that I did not specifically quantitatively measure the growth or decay of the ferns and violets. Measuring the height of the plants would have enhanced my data as it would have better displayed how the conditions facilitated the growth of not only the moss, but also the ferns and violets.
The size of the jar was also a limitation in my experiment, as it restricted the plants' growth. This was evident as by the second week, the plants were leaning against the walls of the jar, and by the fourth week, the ferns in particular appeared limp and lifeless. I should have chosen a larger sized jar to allow both the plants and violets to survive to their full potential.
The main mistake I made in the procedure of my mesocosm was adding too much water in the initial stages of the construction. This was shown by the excess water at the bottom of the jar, although the layer of pebbles did successfully act as drainage. Too much water caused a rise in humidity, which I believe contributed to the decay of the fern, as well as exposure to direct sunlight.
My experiment only lasted for a short period of time, and I obviously would have been able to obtain more detailed results if the process was longer.
My mesocosm was successful to an extent, as the conditions facilitated the growth of both the native violets and the moss. I have fulfilled my aim 'to create a sustainable terrestrial ecosystem' over the period of time that I have measured my mesocosm, however I am doubtful that it could be sustainable for a longer period of time, due to the limiting size of the jar.
The most significant weakness of my experiment was the lack of control in regards to my materials. I collected the soil from my garden, meaning it could contain unknown bacteria and insects. These factors may have affected my experiment although I was unaware of the cause-effect relationship. Also, the plants in my mesocosm were simply from my garden, and this raises similar issues in the accuracy and reliability of my results.
Another weakness in the accuracy of my data is the fact that I did not specifically quantitatively measure the growth or decay of the ferns and violets. Measuring the height of the plants would have enhanced my data as it would have better displayed how the conditions facilitated the growth of not only the moss, but also the ferns and violets.
The size of the jar was also a limitation in my experiment, as it restricted the plants' growth. This was evident as by the second week, the plants were leaning against the walls of the jar, and by the fourth week, the ferns in particular appeared limp and lifeless. I should have chosen a larger sized jar to allow both the plants and violets to survive to their full potential.
The main mistake I made in the procedure of my mesocosm was adding too much water in the initial stages of the construction. This was shown by the excess water at the bottom of the jar, although the layer of pebbles did successfully act as drainage. Too much water caused a rise in humidity, which I believe contributed to the decay of the fern, as well as exposure to direct sunlight.
My experiment only lasted for a short period of time, and I obviously would have been able to obtain more detailed results if the process was longer.
My mesocosm was successful to an extent, as the conditions facilitated the growth of both the native violets and the moss. I have fulfilled my aim 'to create a sustainable terrestrial ecosystem' over the period of time that I have measured my mesocosm, however I am doubtful that it could be sustainable for a longer period of time, due to the limiting size of the jar.