An Oyster Growers Dilemma
Research Question: Where along the Thames River are pH levels best for oyster growing?
Part A: Background
pH
pH is a measure of the concentration of hydrogen ions in a solution. The more hydrogen ions present, the more acidic a solution. The pH scale runs from zero which is very acidic to fourteen which is very basic. A pH of seven is said to be neutral. Distilled (fresh) water has a pH of seven. An example of an acid you might have at home is a lemon with a pH of about 2. Soap is a base with a pH of about 12. The pH of the open ocean is slightly basic, 8.0-8.4. The pH of estuaries like Long Island Sound can fluctuate between 7.0 and 8.0, as the slightly basic salt water mixes with the slightly more acidic fresh water coming down rivers.
Oysters and pH
Oysters are impacted by pH primarily during their reproduction. In order to make their shells, baby oysters need to extract carbonate ions from the sea water - and if the pH is too low (too acidic), there are not enough carbonate ions available in the water. Without proper shells, the baby oysters can die, and larger oysters may have weaker shells. Read more about the impact of changing ocean pH on oyster farms here.
Scientists have found that pH levels of 7.7 and lower can reduce the survival of oyster larvae and the strength of oyster shells (Gobler and Talmage 2017).
Part B: Prediction and Reasoning
If you haven’t already, take the Google Earth tour and think about how the Thames River might vary from its headwaters (where it starts, in Norwich) to its mouth (where it meets Long Island Sound). For this particular research question, assume the scientific measurements are taking place in the summertime.
Write the answers to the following questions on your sheet of paper.
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Make a prediction. Where along the Thames River do you expect the pH to be the highest in the summer? Specify a sampling location (labelled A-F on the map).
2. Explain your reasoning. WHY do you think the pH will be highest at that location?
Part C: Analyze the Data
Look at the dataset below. On your piece of paper, illustrate the data by making a graph. Your graph should have clear labels on both the x-axis and the y-axis. The type of graph (scatterplot, column graph, etc) is up to you.
This table shows the mean pH we measured at each location during trips taken in the summer. Each number is an average of many trips.
Part D: Interpret the Results and Make Arguments from Evidence
Write answers to the following prompts on your sheet of paper.
1. Make a claim that answers the research question at the top of this section (one sentence).
2. What evidence was used to write your claim? Reference specific parts of your graph.
3. Explain your reasoning. Make sure to connect your answer to what you have learned about oyster biology and pH.
4. Was your prediction supported by the results? Use evidence to explain why or why not.
5. Are these readings within the normal range for this area? Standard Ranges for Water Chemistry
6. Revisit the prediction you made at the very beginning, about where might be the best place for an oyster farm. Has your choice of location changed based on what you have learned about oysters and pH? Explain why or why not.
7. How would you follow up to learn more about the potential impacts of pH on your oyster farm? Describe a new question that should be investigated to build on these results, and what future data should be collected to answer your question.
Congratulations! Your final analysis should include the following components:
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Your initial prediction and reasoning about the best location for an oyster farm.
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A statement of the research question that you chose/were assigned
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Your prediction and your reasoning about the research question
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Your labeled graph
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Your answers to the results questions
Share your results with your teacher!