Ecocolumn Lab Wen Lu Mrs. Horner AP Environmental Science Period 1 November 8, 2014 I.
Purpose We had to create a model of an ecosystem. This lab represented what a real life environment would look like and how it would thrive in a small controlled environment where we were able to control factors like sunlight and food. Each habitat had it’s purpose and we were able to closely observe the each habitat helped one another out. We try to make our ecosystem as closely related to the real one as we could. This lab was to really help us understand the different ways each habitat works but also how all of them work together to create an ecosystem in which all the species can thrive with help from one another. II.
Materials ● 6 clear 2­liter soda bottles ● Conditioned water (Aquatic) ● Aquarium gravel (Aquatic) ● Sticks (Predator) ● Betta fish (Aquatic) ● Soil (Terrestrial) ● Terrestrial plants (Terrestrial) ● Duckweed (Aquatic) ● Water Plants (Aquatic) ● Fruit peels (Decomposition) ● Different insects (Terrestrial and Predatory) ● Worms (Terrestrial) III.
Procedure Our group has to obtain 6 empty 2­liter bottles. We were given instructions on how to construct the ecosystem. Following the instructions given to us, we first cut all the bottles accordingly. We had to cut the bottoms off of two of the bottles, just the top off of one bottle, the top and the bottom of another two bottles, and then we had to leave one bottle uncut. After doing all the necessary cutting, we began to put the shell of our ecosystem together. We placed the first bottle, which was the bottle with the top cut off, on the table. Then we stacked a bottle with both the top and the bottom cut off. Next we placed the bottle with just the bottom cut off on top with the spout facing down. After that, we placed another bottle with both the top and and bottom cut off on top. Then we put a bottle with just the bottom cut on top (again with the spout facing down). The bottle that was uncut was placed at the very top. After all of that, we poked holes about the size of a straw into 3 of the bottle caps. Then we put a straw through one of the bottle caps. That was the cap for the very top chamber. Once that was assembled, we began to put in organisms into our ecosystem. We started with the bottom bottle, which was the aquatic chamber. We filled it with some aquatic gravel, then we put the water plants in, then we poured in our conditioned water (about three quarters of the way full), and then finally, we put out betta fish in his new home. The third bottle up was the terrestrial habitat. We filled this chamber with a mix of different soils and then planted the terrestrial plants in the soil. Next, we threw in some worms and crickets. It was really difficult trying to get the crickets in there because the kept jumping everywhere. We set up the predator habitat before the decomposition one. We put our praying mantis in the top with some sticks in it to keep him company. We also named the praying mantis Hubert, but Hubert died. So we ended up putting a spider in the predator chamber to replace him. Finally we completed our ecosystem by filling the decomposition chamber with fruit peels, leaves, and pill bugs. We observed our ecosystem over the period of 6 weeks. We would measure the dissolved oxygen, temperature, pH, turbidity, nitrate, nitrite, CO2, plant health, and the odor every week to ensure that our ecosystem was going smoothly. There were different kits that tested all these things, but some things like the plant health and odor had to be tested by ourselves. We just observed the plants and critiqued their health and we smelled our ecosystem to observe the smell. After collecting all of the data, we recorded them in our table and our lab notebook. IV.
Data Collection DO Temp (°C) pH Turbidit
y Nitrate Nitrite CO2 Plant Health Odor Week 1 5 25°C 7.5 36.9 NTU 2 0 1 ppm great garden/
manure Week 2 5 24°C 6.5 45.1 NTU 16 3 25 ppm dead manure Week 3 5 24°C 8.0 158.3 NTU 5 0 5 ppm dead manure Week 4 4/ 7.24 25°C 8.0 38.2 NTU 5 0 5 ppm dead manure Week 5 6 23°C 8.0 66.4 NTU 5 0 11 ppm dead fish tank Week 6 3/ 8.16 24°C 7.5 43.5 NTU 5 0 6 ppm dead fish tank V. Analysis In the first week of our lab, everything was going great. Our plants were healthy and it seemed that our ecosystem was doing well. When the second week came around, we were surprised to find that our plants had died. Our CO2, nitrate, and nitrite levels were also a lot higher than the first week so we concluded that the death of our plants most likely had something to do with the levels of CO2 and the nitrate and nitrite. There had to be some type of correlation. After seeing out plants die, we expected our ecosystem to start declining and dying, but to our surprise, everything was doing fine on week three. Our dissolved oxygen levels did get below a five in weeks four and six. Because of this, we had to oxygenate the aquatic chamber to ensure that out betta fish survives. The decomposition chamber was decomposing and it looked disgusting. It began to liquify and even leaked into the terrestrial chamber where our dead plants were. We weren’t able to empty out our decomposition chamber due to the fact that another group was emptied it out for us. So we weren’t sure if there were any microorganisms in the decomposition chamber but we did not see any when we observed the chamber. In the terrestrial chamber, it seemed that everything had died, we were not able to find any of the crickets. The worms we did find seemed to be dead and also seemed larger than when we put them in the chamber. The temperature and nitrogen levels stayed pretty much the same towards the end of our experiment. Out test results were pretty similar throughout the experiment except for a few times when the levels were completely different than the previous week. I conclude that this experiment went well but there were some errors that caused unsuccessful survival in some of our chambers. I believe that the holes in the bottom of our chambers couldn’t get enough air flowing through the chambers so it caused a lack of oxygen. Although there was condensation in the terrestrial chamber, probably from water evaporating from the aquatic chamber, there wasn’t enough resources for the plants to survive, even with the decomposition chamber leaking. I think there was an issue of space because we kept all the organisms in such enclosed and small spaces. That might have been another factor to the failure of survival in some of the chambers. The organisms that survived were the ones that were able to adapt to the changes that they were put in quickly.
V.
Conclusion Overall, this project was helpful in learning about ecosystems. It was a hands on experience and our group was able to make conclusions about the changes in the ecosystem on our own, just like how scientists would if it were a real ecosystem in crisis. There were a lot of new equipment that we had to familiarize ourselves with and it really helped us get a peek at how real scientists observe ecosystems. I liked doing this was better than watching a video or demonstration. It was better because we were able to actually experience first hand how things worked and how the different habitats and species worked. I think that this lab helped me better understand the relationship that each habitat has with each other and how they work together to create an ecosystem VI.
Sources of Error I would say that there were quite a few error while we were performing our experiments. Most of it had to do with the fact that we were unfamiliar with equipment that we were given. Since we didn’t know how to use most of the things that we were given, we may have tested some of the things wrong. With a lot of tests, you had to wait. So we had a problem with the amount of wait time. We didn’t know how long to leave things in for or how long we took them out for, so it became sort of a trial and error process. Another error I think we had was that we didn’t make sure that air was able to flow through the ecosystem. But overall, I think it was a good attempt at a first time experiment.