Much research has been done on the effects of certain conditions on microorganisms for the express purpose of determining when pollution begins to adversely affect the ecosystem. As Bruce J. Russell states in 'Life in a Drop of Pond Water', "Without bacteria, no fish, no frogs, no birds, no pretty pond lilies, cattails or sedges would survive. The simple fact is that microorganisms create the ecological foundation for life on planet Earth - a foundation that supports humans and all over living things." (Russell, http://ebiomedia.com/gall/drop/dropmain.html 2002) Bacteria and other microorganisms are surprisingly resilient; considering how many places they can be found. As Francis H. Chapelle says, "it's little wonder that microorganisms display such astonishing diversity." (Chapelle p.32, 2001)
First, the general environment that is being investigated must be described. A pond is a body of water usually smaller than a lake, encircled by vegetation, and generally shallow enough for sunlight to reach the bottom. Algae, which are very small plant-like organisms, provide the base of the food chain in ponds. Algae release oxygen, which are necessary for fish and other aquatic organisms. However, when algae becomes excessive from an overabundance of nutrients, the decaying algae can decrease oxygen levels to a point at which plants and animals die. The problem with fertilizers is that they encourage too many algae to grow. When the algae die, their decomposition by aerobic bacteria takes oxygen out of the water, thus killing many fish or other life that relies on dissolved oxygen in the water. The amount of dissolved oxygen is an important indicator of water quality. (www.lalc.k12.ca.us 2002) Excessive nutrients can result from agricultural processes, runoff from fertilized lawns and fields, and septic tanks. (www.epa.gov 2002)
Each of the factors previously listed comprises the organism’s environment, so the effects of each need to be individually analyzed.
pH, a measure of acidity in water, is very important to most forms of life. It effects many chemical and biological processes. Most aquatic animals prefer a range of 6.5 to 8.0. Anything outside of this range is most likely caused by mine drawings and industrial wastes. (www.beesinc.org 2002)
Phosphorus is an essential nutrient for plant growth and for metabolic reactions in plants and animals. There is a delicate balance between plants and animals for phosphorous. If, for example, animals develop phosphorus fixation and consume too much, algae will die. (www.biologic.de 2002) If there is too much phosphorus, plant life may choke out living animals. (www.beesinc.org 2002)
Dissolved oxygen measures the presence of oxygen gas molecules in water. Oxygen is essential to keep organisms living, to sustain species reproduction, and for many chemicals processes that happen in water. Water with higher dissolved oxygen is generally considered healthy, and more capable of supporting a variety of lives. Warm water can hold less dissolved oxygen than cool water. The amount of oxygen consumed by all of the biological processes is called biochemical oxygen demand (BOD). If the amount of oxygen that is consumed is greater than the amount produced by photosynthesis or by diffusion from the surrounding air, dissolved oxygen levels decline, and the ecosystem suffers. Bacteria often processes oxygen, taking raw nitrogen gas transforming it into usable biological nitrogen (www.beesinc.org 2002).
Temperature affects the rate of many of the waterway’s biological and chemical processes and the amount of oxygen gas that can dissolve in the water. Organisms can only live and reproduce within a certain temperature range. It also affects the rate of photosynthesis of plants and the rate of decomposition. Therefore, ‘heat pollution’ is created when factories or other industrial centers use water to cool machinery, then dump it into ground water, cause high temperature fluxes which kill off local organisms. (www.beesinc.org 2002)
Though there is great diversity in species of bacteria, they all fall into four recognizable basic categories based on shape. These shapes are Coccus (round), Coccobacillus (oblong), Bacillus (pill-shaped), and Spilillum (spiral shaped) (Lundy 2002).
The presence of microorganisms themselves can be indicative of a healthy environment. The presence of algae such as Navicula and Cocconeis indicates clean water. On the other hand, algae such as Euglena, Spirogyra, and Nitzschia indicate polluted water. (Chapelle p. 32, 2001)
Materials and Methods
In our experimental design, we will be testing five variables of dissolved oxygen, pH, temperature, phosphorous levels and plant life by testing the samples and/or taking measurements in the field. We selected these variables based on their relevance to the topic and the ease with which we can measure them. We are not measuring current, for example, because the process would be difficult and expensive. Statistically, the results will prove accurate as long as we take enough measurements and samples. We were advised that the more variables we have and the more times we test them, the more accurate our results will be. To ensure unbiased results, we will choose random testing locations in the pond. To ensure that the class collects accurate data, we will keep records of our own data to ensure that they were in collusion. There will be a grid mapped to determine the location of each sample. The grid will include boxes with an area of two square meters. Each row and column will be assigned a value. These values will then be entered into a random letter/number generator to ensure a random value for each measurement.
A representation of the grid system to be used.
(unable to view on internet posting)
Materials used will be primarily for testing and observation. We will use milliliter droppers to collect the samples and microscopes to observe them and count microorganisms. Temperature will be gauged with a thermometer, temperature with a digital thermometer, which will then be measured. Phosphorous, dissolved oxygen and pH levels will be gauged using specialized chemical tests, and plant life will identified by counting the number of specimens in each grid. The class will be asked to use similar methods to gauge the variety of variables to be tested.
Five measurements will be taken each weekday for two weeks, starting on the 23 of October. The measurements will be taken between noon and 5:00. The data will be analyzed at the end of each week, so that a completed data table will be produced at the end of the period. This can be shortened to allow for time constrictions.
Chapelle, Francis H., Ground-Water Microbiology and Geochemistry. John Wiley &
Sons Inc., New York, New York. 2000 'EPA-Lakes and Ponds' Online. http://www.epa.gov/maia/html/lakes.html 9/26/02
Geiszler-Jones, Amy. 'Ponds, Scum, Bacteria Usually Helpful'. Online.
Kemp P., Sherr B., Sherr E., Cole J., eds. Handbook of Methods in Acquatic Microbial Ecology. Boca Raton FL: CRC Press, Inc 1993
'Microoraganisms'. Online. http://www.lalc.k12.ca.us/target/units/river/tour/micr.html
Russell, Bruce J., 'A Drop of Life'. Online.
'Water Monitoring'. Online. http://www.beesinc.org/resource/currenha/watmonit.html.
Lundy, Dan. ‘Bacteria Shapes and Sizes.’ Online. http://dl.clackamas.cc.or.us/ 10/10/02
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