Biology and Population Growth Rate


Cover Sheet I certify that the writing in this assignment is my individual work and is my sole intellectual property. It does not contain the ideas, or writing of other individuals/authors. Author: Mark Cooper Jr. Date: 10/24/12 Lab Instructor: Katherine Hovanes Lab Section # 12 Population Ecology Experiment Background: Phosphate is an abiotic factor; therefore, it is a nonliving factor that affects living organism. In this experiment we prose to test the whether variation in environmental phosphate levels affects autotrophic organisms.

We ran a lake and Chlamydomonas experiment in order to determine a solution for this question. In our lake experiment we took samples of water from University Lake a recorded the phosphate level and the chlorophyll absorbance readings. Chlorophyll absorbance readings are used to indirectly measures autotrophic organism levels within different situations. Similarly, in the Chlamydomonas experiment we added a control, low phosphorus, and high phosphorus treatments to populations of Chlamydomonas. Chlamydomonas are a genus of unicellular green algae called Chlorophyta. Wishchusen) In the Chlamydomonas experiment, we recorded the chlorophyll absorbance readings for each treatment over 21 day time span. General Question: How does variation in environmental phosphate levels affect autotrophic organism? Specific Question: How does phosphate levels influence population growth rate of Chlamydomonas in a laboratory setting? How do phosphate levels influence the abundance of aquatic autotrophic organisms in the lakes? Hypothesis: Chlamydomonas Experiment (Population): Phosphorus Factor

Null: The level of phosphate will not affect the population growth rate in a laboratory setting. Alternative: The level of phosphate will affect the population growth rate in laboratory setting Prediction: The high phosphorus treatment will have the highest level of population growth rate in a laboratory setting. The low phosphorus treatment will have the second highest level of population growth rate in a laboratory setting, and the control treatments will also an increase in population growth rate but it will be the least amount of growth of the three treatments.

Lake Experiment (Ecosystem): Phosphorus Factor Null: Phosphate levels will not influence the abundance of aquatic autotrophic organisms in the lakes. Alternative: Phosphate levels will influence the abundance of aquatic autotrophic organisms in the lakes. Prediction: High levels of phosphate will cause an increase in the abundance of aquatic autotrophic organisms in the lakes. Results: Figure. 1: The graphed data represents the growth rate of algae cells (population sizes million cells/mL) in each treatment over 21 day time period.

We graphed the population sizes of the control, no-phosphorus, and high-phosphorus treatment. The control group contained 1 ml of Chlamydomonas and 4 ml of phosphate. The no-phosphorus group contained 0. 5 ml of Chlamydomonas and 4. 5 ml of phosphate . The high-phosphorus treatment contained 3 ml of Chlamydomonas and 2 ml of phosphate. Trend: there is no specific trend represented in the graph. However, No-Phosphorus contained the highest population growth rate with a slope of . 19953.

The Control and High-Phosphorus treatments had a similar growth rates. However, the Control treatment was higher than the High-Phosphorus treatment. The Control treatment possessed a slope of . 1535, and the High-Phosphorus treatment slope of . 1407 for. Figure2: The data above was collected from University Lake from Spring 2009 to Spring 2012. The average phosphate levels and the average chlorophyll absorbance are the point graphed in the data. The levels of phosphate were graphed in response to its chlorophyll absorbance; in other words, the data epresents the chlorophyll absorbance/algae level in each water sample in response to their phosphate levels. Trend: There is not a trend in the data. Discussion: Chamyl Conclusion: In these experiments, we fail to reject the null and accept the alternative hypothesis. Phosphate levels do influence the population growth rate of Chlamydomonas in a laboratory setting. Phosphate, an abiotic factor, is a nonliving factor that affects living organisms. Phosphate is a source of nutrients for the Chlamydomonas.

Therefore when the phosphate was added to the population Chlamydomonas it caused the growth rate to increase with each treatment. In our results the high-phosphorus treatment had the lowest growth rate because it contained a high amount of Chlamydomonas to begin the experiment. Therefore this treatment did not have much room to grow. The control treatment had the second highest growth rate because it contained more Chlamydomonas then the no-phosphorus but less Chlamydomonas than the high-phosphorus treatment.

The no-phosphorus treatment had the highest growth rate because he had the least amount of Chlamydomonas to begin with having the highest potential for growth. Lake Conclusion: In this experiment, there were no significance trend chlorophyll absorbance/algae levels as a function in response to phosphate clarity. Therefore, we accepted our null hypothesis and rejected our alternative hypothesis. The data supports the null hypothesis and we found no differences between treatments General Conclusion: In conclusion, phosphate levels did effect the population growth of the Chlamydomonas in the laboratory setting.

However, phosphate levels of water had no effect on the abundance of aquatic autotrophic organisms. Research could show that factors other than phosphate factors in lake water could have an effect on the aquatic autotrophic organisms