Environmental Science Lab Report

1669 Words Apr 12th, 2013 7 Pages
Estimation of Duckweed Geometric Population Density
Phosphate Depletion
By Ana Rosina Alarcon
University of Texas at El Paso
Department of Environmental Science
Instructor: Gebregiorgis Alay G.

Introduction Duckweed is a small aquatic plant that is able to grow rapidly, making it the ideal specimen for our experiment. It is hypothesized that altering the amount of light received by duckweed will alter its photosynthetic rate. It is predicted that a lower light intensity will lower the rate of growth in duckweed. Also is an important high-protein food source for waterfowl and also is eaten by humans in some parts of the world. As it contains more protein than soybeans, it is sometimes cited as a significant potential
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After all this is done measure the length and with of the thalli to estimate the average of the growth of the duckweed itself to understand not only the reproductive growth rate of the thalli but the size of the plant as well. Record all the data gathered in the experiment and all steps have been completed evaluate whether the hypothesis was correct and record all results to conclude how phosphate depletion has affected the growth rate.
Results:
As the lab concluded the results were both evident and significant. It is very clear that by eliminating phosphate in the water the duckweeds growth rate is slowed down significantly, the control group which had a good amount of phosphate to provide nourishment for the duckweed reproduced not only fast but efficiently as well, the number of thalli in each control group doubled the first week, and kept a steady growth rate through the following weeks of the experiment, while the lacking phosphate group hardly even doubled by the time the experiment was over, the growth rate was slow, but steady, and very clearly demonstrated that without phosphate as a nutrient the duckweed cannot grow to its full potential.
This graph demonstrates the growth rate for both groups:
Control Group: | number of thalli | replicate | Week 0 | Week 1 | Week 2 | Week 3 | Week 4 | Week 5 | 1 | 64 | 250 | 324 | 484 | 530 | 940 | 2 | 62 | 256 | 453 | 614 | 67 | 963 | 3 | 82 | 286 | 414

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