“Anacharis Biosphere”
By George F.K. Haddad
Gibson’s Honors Biology: Period 3
I. Introduction
In an ecosystem, there are four types of cycles that keep the lifeforms thriving; these cycles are the phosphorus cycle, nitrogen cycle, water cycle and carbon cycle. On our planet, phosphorus is usually found naturally in decomposing animal tissue, fecal matter and waste. Nitrogen is also found in these forms, but can also move throughout the cycle through nitrogen fixation and denitrification by lightning and bacteria. Water flows throughout the ecosystem by first evaporating in the air and then condenses into cloud in the atmosphere. The water then condenses around particles in the air and falls down as precipitation. The water is then collected in the aquifer, and runoff flows back into the bodies of water in the ecosystem. Water is transpired by plants as well as oxygen in the carbon cycle. Carbon in the carbon cycle is mainly found in nature as solid waste materials like decomposing flesh and feces, but carbon can also be found in a gaseous form called carbon dioxide. As plants release oxygen into the air, animals use it to stay alive and create carbon dioxide through aerobic processes that require oxygen to create sustainable molecules such as the Krebs Cycle and the Electron Transport Chain.
When talking about the fathead minnow’s death in a biosphere, the usual culprit behind most deaths is either too much of a nutrient that is present in the water. This is usually due to nitrogen or phosphorus leeching into the soil, causing the minnow to die of nitrogen or phosphorus poisoning. Nitrogen and phosphorus are present in the Miracle-Gro soil that is present in the biosphere that encourages plant growth, yet it will kill small animals like the minow. Too many nitrates or nitrites will cause methemoglobinemia, a condition where the body cannot use oxygen effectively (Poison Control). Phosphorus poisoning causes the body not to use minerals, like iron, calcium and zinc properly (Healthline). Not only could nitrogen and phosphorus be dangerous for the fathead minnow and other animals, but the most vital molecule, oxygen, could potentially be poisonous as well. Another possibility that could kill the minow would be too much oxygen; symptoms include behavior changes, disorientation and seizures (Dive Rite). Too little oxygen would suffocate the fish as well causing damage to neural tissue that will result in death.
We hypothesized that if we added the Anacharis plants and algae to the fish’s aquatic area and build the biosphere to accommodate the additional oxygen that is being created, then the fathead minnow should survive during the duration of the experiment. In order to keep the minnow nourished, we needed to give the minnow a food source that wouldn’t decomposed into nitrates and nitrites and potentially kill it. Our group believed that a plant would be the best choice to be a food source, for the Anacharis is durable and would balance out the nutrients found in the water as waste. Also, we added algae to help with this, but we didn’t add much of it. Too much aglae would cause additional oxygen that would have made the goldfish die. The minnow was relatively small; therefore, space wasn’t a huge problem. We gave the minnow enough food to supply him for the month, but the biosphere needed to compensate for the additional oxygen created by the plant life. In order to counteract this additional oxygen, we added an extra cricket into the biosphere and taped straws on the sides of the biosphere to allow for carbon dioxide and oxygen to flow freely throughout the biosphere.
Aside from the technical application that is presented in this experiment, I believe this experiment to have a moral to be taught to all of us. The purpose of this experiment is to show how fragile our life sustaining cycles are on our planet. The Earth’s biosphere has sustained life for more than 500 million years, yet when a group of determined teenagers try to keep a goldfish alive, it dies within a week. I believe this biosphere project gave us a deeper insight on how truly fragile and unpredictable life is and how our mistakes can potentially kill an organism or worse, a mass extinction.
II. Materials
2 plastic 2-liter soda bottles, clear
2 medium-sized crickets from PetCo
1 Fat-headed minow, Pimephales promelas
A handful of Anacharis plants, Elodea, 11 cm in height
Approximately 1 cup of pebbles, rinsed off
Kentucky Rescoe grass seeds
MiracleGro dirt
Procedures
Cut the top of one bottle off.
Cut the bottom of the other bottle and keep the bigger section with cap intact.
Fill the bottom of the latter till it is an eighth of an inch thick after they were rinse in order to knock off chlorine and other deadly trace chemicals.
Place Anacharis plants in the gravel and press them gently.
Place algae and goldfish freely floating in the water.
Poke an eighth of an inch diatmeter hole in the cap and hot glue wick after you place it through the hole and twist cap on the bottom half.
Tape 8 straws to the side of the bottle filled with water.
Place the top of the 2-liter upside down in the position that allows the wick to touch the wate and tape it.
Fill the top with dirt and sprinkle grass seeds over the dirt.
Mix the seed up into the dirt until the seeds are all under the dirt.
Place the bottle with the bottom cut off over the apparatus and seal it with tape. Place two crickets through the hole in the top and twist the cap.
Control- The control group of this experiment is a fish from Mr. Gibson’s fish tank, since we are discussing the possibilites of a fat headed minow’s chances of survival are jeopardized when we put it in our bottled biosphere compared to is original placement.
Variables- Variables that we can use in order to predict if are fat headed minow will survive or not would be: water level, the amount of water vapor present on the sides of the bottle, Anacharis plant height and grass height.
Measurements- Our measurements will consist of using centimeters and our own observations.
III. Data Collection and Analysis
IV. Discussion and Conclusion
In this experiment, our hypothesis was proven to be incorrect. The fathead minnow’s death must have been caused by what we believe to be either a depletion or excess of a nutrient in the water. Since abiotic factors usually do not effect the fish as much when others preform this experiment. Therefore, we can start by looking into how the four cycles sustained life in the biosphere and the faults of our design of our biosphere to see where and how the nutrients attributed to the death of the goldfish.
Our first culprits for the goldfish’s death would be excess phosphorus or nitrogen present in the water. This is usually caused by decay of biomass, or the nitrogen and phosphorus from the soil diffusing into the water and poisoning the fish. However, the water seemed to be relatively clean before the minnow’s death; this may be due to the aquatic plant life in the fish’s area may have balanced out the amount of nitrogen and phosphorus present in the water to non-lethal levels. The data proves that the minow could not have died of a fault in the phosphorus or nitrogen cycles, so we can conclude that these two cycles may not have affected chances of the minow’s survival dearly.
Another possible culprit of the minow’s death may be the excess or depletion of oxygen. Oxygen is a main component in the carbon cycle and is vital for life to occur on Earth. Plants create oxygen mainly from the carbon dioxide that animals give up and use it to create sugars and oxygen as well. However, there is a good deal of evidence that shows that the minow’s death was caused by too much oxygen in the biosphere’s atmosphere.
The evidence to proves this is that plant life was thriving in these conditions in the early half of the experiment. According to our data, the height of the grass in our biosphere reached 17 cm, and the Anacharis plant grew from 10.5 cm to 13 cm. This shows that the creation of oxygen increased as the plants grew, but the amount of carbon dixoxide being created remained fixed. In fact, the amount of carbon dioxide dropped as one of the crickets died during the experiment, leaving only one cricket and fat headed minow. We may have overestimated how much biomass the minow would eat, allowing for the Anacharis plant to still produce oxygen. This caused the atmosphere in the biosphere to become staturated in oxygen, which affected the minow’s health and behavior.
According to the National Institute of Health, the symptoms of oxygen toxicity are “vertigo and nausea, followed by altered behaviour, clumsiness, and finally convulsions result.” During the recording of data for this project, I found the minnow’s behavior to be quite unordinary as it still wasn’t accustomed to its surroundings for multiple days. Even though this may have been caused by other stimulus, I believe these symptoms to be a sign that our minnow underwent oxygen toxicity.
Another sign of evidence that oxygen toxicity led to the death of the minnow was the browning of the Anacharis plant. Since carbon dioxide wasn’t being created to compensate for the amount of oxygen being created, plants didn’t have enough carbon dioxide to phototsyntehsize into sugars that are necessary to sustain themselves. Therefore, they started to decay and brown. According to our data, the Anacharis plant growth subsided around day 18. The Anacharis plant seemed to not have been affected by the deficiency of nitrogen or phosphorus, since the minnow’s corpse decayed in the water and gave nutrients that could help it sustain itself.
Conclusion
In conclusion, the minow’s death seems to have been caused by an excess of oxygen in the biosphere. This is most evident in the growth of the grass and Anacharis plants, as seen in graphs 1 and 2. After the minow’s death, the aquatic life sustained itself with the nutrients from the minow, and evident it our data table. The effects of the staturation of oxygen on the minow’s health is seen in the degrading behavior and mental capacities of the fish. It seems to us that the minow could not have died of nitrogen or phosphorus poisoning as the water seemed relatively clean in the biosphere. This experiment shows how fragile life truly is when we unknowingly poison it with our good intention for its survival.
V. Works Cited
Chawla, Anuj, and Ak Lavania. “Oxygen Toxicity.” Advances in Pediatrics., U.S. National
Library of Medicine, Apr. 2001, www.ncbi.nlm.nih.gov/pmc/articles/
PMC4925834/.editmore horizontal
“Nitrate/Nitrite Poisoning, Why So Blue?” Poison Control, 2012, www.poison.org/
articles/causes-and-symptoms-of-nitrate-nitrite-poisoning-174.editmore horizontal
“Phosphorus in Your Diet.” Healthline, Healthline Media, 2005, www.healthline.com/
health/phosphorus-in-diet.editmore horizontal