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 organisms require 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 and then answer the questions below.
QUESTIONS
1. Make an observation – Based on the data in Table 4, describe the relationship between dissolved oxygen content and fish populations in the body of water. Discuss the pattern observed in the data set.
Answer = The more parts per million of dissolved oxygen in water, the higher the fish population. 2. Do background research – Utilizing at least one scholarly source, describe how variations in dissolved oxygen content in a body of water can affect fish populations.
Answer = Most dissolved oxygen in fresh water is derived from photosynthesis of aquatic plants and algae. According to Francis- Floyd (1992), optimum dissolved oxygen levels should be 5mg/L for fish production (p. 1). Depending on species, sensitivity can occur between 2-4mg/L, and sensitivity is species specific. Mortality of species usually occur at
2mg/L or below. Mortality from lack of dissolved oxygen is seen in larger species before low oxygen levels are seen in smaller species. Causes of low dissolved oxygen levels include hot, cloudy weather, algae die offs, or heavy thunderstorms (Francis-Floyd, 1992).
3. Construct a hypothesis – Based on your observation in Question 1 and your background research in Question 2, develop a hypothesis statement that addresses the relationship
