Chapter 2. ECOLOGY—OVERVIEW

Learning Objectives

Lab 7
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General Purpose

Conceptual

  • Be able to determine changes in the University Lake system based on various biotic and abiotic data.
  • Be able to analyze the data collected in the population growth experiment.

Procedural

  • Be able to properly graph data.
  • Be able to properly communicate results to a scientific audience in both written and oral form.

General Purpose

Populations within an ecosystem grow and their growth is impacted by the ecosystem’s biotic and abiotic factors (either singly or in combinations). You have examined the impact a single factor can have on the growth of a population in a controlled setting. You have also measured biotic and abiotic factors in an ecosystem. The challenge now is to combine those aspects to address how information from a controlled experiment may be used to help understand what may be happening in an ecosystem where complex interactions are occurring.

To start the process of integrating the two separate experiments, answer the following two questions and write the answers in your laboratory notebook.

  • Chlamydomonas population ecology experiment?
  • Given that it will be easier to write a cohesive paper including Chlamydomonas data and the lake system if the parameters studied are similar, what lake aquatic measurement could you write about?

Discuss with your lab partners and your lab instructor how you will approach the integration of the two different experiments. Recognize that to do this effectively you may need to compare and contrast the data from different sites or from different time points (or both). To prepare for that type of analysis, answer the following questions with your partner using the compiled data sheets. Write the answers in your laboratory notebook.

  • Are dissolved oxygen levels higher in the spring, summer, or fall?
  • Would you expect to see more autotrophs present in the spring, summer, or fall based on this result?
  • Are chlorophyll levels higher at sites where nitrite levels are higher? Explain possible reasons why or why not in terms of autotrophs and heterotrophs.
  • The University Lake system has high levels of phosphate in the bottom sediment. Will this stimulate the growth of autotrophs or heterotrophs?
Click here for compiled data sheets.