Water analysis of a closed ecosystem

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The lab intended to simulate a closed ecosystem, and all of the factors that a particular system possesses. Examples of observable factors were food chains, nutrient cycles, and chemical processes. Over time, one was able to view the factors of the column and how they coalesced within a simulated ecosystem.


Using a complex assortment of techniques, the lab posed several factors of observation. The advisor provided construction and preparation of the structure of the eco-column prior to the testing. The column was functioning on 9/17/13 and lasted until 12/03/13 accumulating seventy-eight days of use. This allowed for ~ six testing events in which soil and water quality was tested.

Implementation of Biotic and Abiotic Material: All materials were gathered over a timespan of seven days (9/11/13-9/17/13).

  • The terrestrial level of the eco-column consisted of gathered materials such as: sediment from horse arena, dirt contained with bait (red worms), red worms, Armadillidium vulgare, centipedes, slugs, and a cricket.
  • The aquatic level of the eco-column contained few materials such as: water from a local lake and stones from a lakebed. Elodea was also implemented into the aquatic chamber.
  • The decomposition level of the eco-column had materials such as: rotting apples, hay, and leaf litter.

Water Quality Testing: several aspects of water quality were tested over a timespan of several weeks (9/24/13-12/03/13).

  • pH Testing: The pH was tested using a probe in which a group member would inject into the water, and later rinse and clean with distilled water.
  • Dissolved Oxygen Testing: The D.O. levels were taken via probe, a member would ensure the precision of the device then cautiously move the probe around the water. After using the probe a member would rinse and clean with distilled water and store the probe properly.
  • Turbidity Testing: The turbidity was tested using a mechanism and vial to determine the water clarity. A group member would rinse the vial with the water that was to be tested. After inserting the vial into the machine, the member would rinse the vial with distilled water.

Soil Quality Testing: First, a member would mix soil with water into a container, due to clarity issues we waited an extra week every soil test. After the water was usable, a member would use a pipette to extract and move into a testing container.


Water Analysis


Dissolved Oxygen






1.5 mg/L


21.8° C

37.5 NTU



1.1 mg/L


22.8° C

72 NTU



1 mg/L


20.8° C

125.4 NTU



1.2 mg/L


20.4° C

153.4 NTU



3 mg/L


17.2° C




6.8 mg/L


17° C

65.4 NTU


In figure 1, one is able to view an extremely low average of dissolved oxygen results. This is likely caused by the lack of oxygen in the chamber by eutrophication, the algae uses all of its needed nutrients until it runs out and dies. Once the algae dies aerobic bacteria begin to eat away at the dead matter. As they consume they are also using oxygen, which causes the oxygen levels to lower and brings death to all living things within the chamber. Figure 2 illustrates the turnaround point in dissolved oxygen as it starts to rise between 11/5/13 and 12/3/13.


  1. Identify two Food Chains or Food Webs in each of your habitats (chambers). Use arrows to illustrate these food chains and food webs; complete sentences are not required. Use extra paper if needed.
  • Aquatic Chamber
    1. In the aquatic chamber one there was a simple food chain, in most cases only bacteria would feed on decaying algae.

decaying algae ƒ  Bacteria

  • Decomposition Chamber (top soil chamber)
    1. Another form of a simple food web was in the decomposition chamber, where the fruit flies would feed on the rotting organic materials.

rotting organic material ƒ  fruit flies

  • Terrestrial Chamber
    1. With a variety of organisms in the terrestrial chamber, a food web was evident. Fruit flies, slugs, Armadillidium vulgare, worms, a cricket, and centipedes all formed a food web.

Plant leaves ƒ  Armadillidium vulgare, centipedes, slugs, and cricket.

Decaying matter ƒ  worms and fruit flies.

  1. Identify and briefly discuss the biogeochemical cycles which are taking place/which are present in your EcoColumns. Do not merely state that “they are all present”; instead, provide more specific information.

Unlike the other groups, this particular column endured inhabitable circumstances. These circumstances like excess nutrients leading to eutrophication caused the entire system to be off balance. The off balance situation caused all biogeochemical cycles to act in an unknown fashion, where nutrients fluctuated in off-set patterns.

  1. Is your ecosystem column a closed or open system? --- or is it something in between a closed or open system? Explain how this (closed, open or other) influences the ecosystem column overall.

The column was a closed system, where what was inside of the column stayed. Though the column was sealed, organisms were able to thrive. For example, the fruit flies reproduced rapidly throughout the entire function. The lab was a simulation so there was no true “ecosystem,” though most aspects of the real world were covered.

  1. What kind of niches are available/present for the various organisms in the column? Be specific, descriptive, and use terminology that is pertinent to the topic.

Within the timespan of the eco-column, one was able to view a few niches. One example would be the spacing of the slugs. Every slug seemed to have their own area, for they were never close to one another. As of 10/1/13, members were able to determine a lack of living organisms within the column. This downfall of life within the column made many niches impossible to record.

  1. Discuss evidence of ecological succession taking place in your column (or in the column of another lab group if you have not observed any signs of succession in your column).

A gradual change was evident within the eco-column. After a few weeks of functioning, members were able to see a drastic decrease in living organisms. Also, the water quality drastically changed, dissolved oxygen levels reached low results (1.0 mg/L – 3.0 mg/L). These processes were likely to overturn the entire system due to excess nutrients.

  1. Discuss the stability and sustainability of the ecosystem columns in the lab, including your own.

Other than two groups all columns was easily considered stable and sustainable. In the case of the column in which this report covers, things bottomed-out. Specifically in the aquatic chamber, group members viewed massive loss of proper nutrients. For example, turbidity levels were somewhat stable at the beginning, average around 37.5 NTU, but eventually roared in numbers and maxed at 153.4 NTU.

  1. Discuss three trends or patterns which stand out as you think back on the data which you have been recording for 6 weeks. These trends or patterns should apply to the water quality tests or other observations which you have made over this multi-week time period. Briefly discuss these three trends or patterns, providing possible explanations based on environmental science principles.

Low Dissolved Oxygen Levels: In the aquatic chamber members seen drastic loss of nutrients. The low results of D.O. was an indicator of the nutrient loss. For five consecutive weeks results were <5.0 mg/L, and this proves an issue in nutrients.

Rising Turbidity Levels: Throughout the observations turbidity levels rose every testing. This is likely due to the loss of required nutrients. When the nutrient levels lessened the amount of dead organic matter built up, in turn this made the water more turbid.

The Slow Return of Stability: Though the majority of testing was considered low and inadequate for a stable ecosystem, a gradual return of stability was evident. The last testing day proved this statement, for all of the categories of water testing leveled out and began to be considered more desirable for a stable ecosystem.

  1. Explain what eutrophication refers to and how this occurs. Apply this explanation to your ecosystem column. How might eutrophication take place in your column? Explain fully.

Eutrophication occurs when there are excess amounts of nutrients, and algal blooms enter the aquatic zone. The column tested in this report underwent eutrophication due to excess nutrients. The process brought detriment to the stability of the column, for the algae consumed most of the nutrients and eventually shut the aquatic chamber off from stability.

  1. Pick another group in your class. How do your data compare to theirs? Brainstorm some causes/reasons for any differences.

Group 1 (Julius, Alondra, Mariah, Maggie)

Dissolved Oxygen: 1.5, 1.1, 1.0, 1.2, 3.0, 6.8

Turbidity: 32.5, 72, 125.4, 153.4, ---, 65.4

pH: 5.5, 6.89, 7.05, 7.85, 8.4, 7.63

Temperature: 21.8, 21.8, 22.8, 20.8, 20.4, 17.2, 17

Group 2 (Jenny, Ying, Yang, Jilda)

Dissolved Oxygen: 5.2, 7.4, 7.8, 7.0, 3.0,

Turbidity: 29.9, 37.6, 35.1, 44.5, 34.5

pH: 6.24, 7.2, 6.01, 7.08

Temperature: 21.7, 21, 21, 17.9

A difference in variables is evident, the most probable cause is group one’s loss of proper living requirements. An example of a lacking element necessary for life is the dissolved oxygen, group two actually has stable numbers, while group one has extremely low amounts. The likely cause of group one’s inability to sustain is the excess amount of nutrients that were introduced into the system. The excess nutrients caused eutrophication; the algal blooms simply overtook the aquatic chamber and caused a chain reaction of downfall.

  1. Finally, address any sources of error in this lab. This should be narrated in a “cause and effect” manner and talk about specific problems. A good example would be “water did not drain from the terrestrial chamber so …” while a bad example would be “we messed up the measuring one day.”

A major error occurred on the testing day 12/03/13, two members improperly attempted to test the soil. Unlike other testing days, the members shook the water, which disturbed the clarity making it impossible to test, and caused any results to be faulty.


This lab posed a variety of learnings, and invoked a greater view of an ecosystem. This stands true because one was able to view an entire system on a much smaller scale. The importance of biogeochemical cycles was understood. The complexity of an ecosystem was learned, and appreciation of a true ecosystem was gained.


Houston, H. (9/18/13). Eco-column Help. AP Environmental Class. Lecture conducted from Bunker Hill High School, Claremont, NC.

Botkin, D. B. (2010) Environmental Science: Earth as a Living Planet. Danvers, MA: John Wiley & Sons, Inc.

Baily, Jeffery. "UCSB Science Line sqtest." UCSB Science Line sqtest. National Science Foundation, n.d. Web. 19 Dec. 2013. <http://scienceline.ucsb.edu/getkey.php?key=1258>.

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