Revision on science assignment

Lab 1 – Introduction to Science

Exercise 1: The Scientific Method

Dissolved oxygen is oxygen that is trapped in a fluid, such as water. Since many living organism requires oxygen to survive, it is a necessary component of water systems such as streams, lakes and rivers in order to support aquatic life. The dissolved oxygen is measured in units of parts per million (ppm). Examine the data in Table 4 showing the amount of dissolved oxygen present and the number of fish observed in the body of water the sample was taken from; finally, answer the questions below.

QUESTIONS

1. Make an observation – Based on the data in Table 4, discuss what patterns you observe in regards to dissolved oxygen content and fish populations in the body of water?

Answer = It appears the fish numbers increase as the dissolved oxygen increases. It also seems that 15 fish may be the max number of fish for this eco system.

2. Do background research – Utilizing at least one scholarly source, describe how the dissolved oxygen content in a body of water can effect fish populations.

Answer = In an article I read it stated that “P¨ortner & Knust (2007) reported that a mismatch between the demand for oxygen and the capacity for oxygen supply to tissues was the first process that caused mortality of aquatic organisms or their relocation to cooler water, when water temperatures increase”. (Elshout, P. F., Dionisio Pires, L. M., Leuven, R. W., Wendelaar Bonga, S. E., & Hendriks, A. J. 2013) The article also talked about climate change with high death rates due to rising temperatures. This in turn leads to changing biodiversity’s.

3. Construct a hypothesis – Based on your observation in question 1 and your background research in question 2, develop a hypothesis relating to the amount of dissolved oxygen measured in the water sample and the number of fish observed in the body of water?

Answer = Fifteen fish may be the max capacity for that oxygen supply with that current water temp and body of water.

4. Test with an experiment – Describe an experiment that would allow you to test your hypothesis from question 3. This description must provide ample detail to show knowledge of experimental design and should list the independent and dependent variables, as well as your control.

Answer = I would take 3 200 gallon water tanks. I would fill them with the same rocks, but vary the number of plant life in each tank. I would fill each tank to 175 gallons and vary the water temps by 10 degrees in each tank (IE 50, 60, 70 degrees F). I would also let the fresh water plants remain in the water for 1 week. After 1 week I would measure and record the Dissolved Oxygen in each tank. Then I would start adding the same amount of fish to each tank, slowly increasing the numbers of fish every 3 days. Before I added the fish I would record the Dissolved Oxygen amounts and record them. I would continue this until the fish started dying off in each of the 3 tanks.

5. Analyze results – Assume that your experiment produces results identical to those seen in Table 4, what type of graph would be appropriate for displaying the data and why?

Answer = Bar graph. You could show each of the three tanks Dissolved Oxygen levels as well as the number of fish per calculation.

6. Analyze results - Graph the data from Table 4 and describe what your graph looks like (you do not have to submit a picture of the actual graph!).

Answer = I would use a bar graph. I would put the parts per million (ppm) going vertical and the number of fish horizontal. The graph would show that with the number of fish going up then Dissolved oxygen would up as well. Once the fish hit fifteen in the tank then the fish start to die off.

7. Draw conclusions - Interpret the data from the graph made in Question 7. What conclusions can you make based on the results of this graph?

Answer = I can make a decision once the tank hits fifteen fish. If the fish start to die off I could conclude the max capacity of fish is fifteen in the tank.

8. Draw conclusions – Assuming that your experiment produced results identical to those seen in Table 4, would you reject or accept the hypothesis that you produced in question 3? Explain how you determined this.

Answer = I would accept the hypothesis in the fact that it would show that with increased temperatures and fish that the eco system could not handle that amount of dissolved oxygen.

References

Elshout, P.F., Dionisio Pires, L.M., Leuven, R.W., Wendelaar Bonga, S.E, & Hendriks, A.J. (2013). Low oxygen tolerance of different life stages of temperate freshwater fish species. Journal of Fish Biology, 831(1), 190-206. Doi:10.1111/jfb.12167