## Acid rain and the survival of fresh water guppies (Poecilia reticulata) |

The materials required for this experiment are as follows:

- 50 freshwater guppies (all fully grown)
- 5 fish tanks (not necessarily very large - as they are each required to hold only 1 liter of water)
- 6 liters of water
- 1 small bottle of vinegar
- 1 syringe (50-100ml)
- 1 small fishing net (to transfer the fish)
- litmus paper (you can purchase litmus strips at a drug store)
- 1 wooden spatula (large enough to mix the water in the tank)
- 1 clock (to record time)

- For this experiment, the independent variable is the acidity or pH level of the water in the fish tanks. The dependent variable is the number of fish that remain alive in the tank over time. This is determined by counting the fish that are still alive every 2 hours. The constants (control variables) are the type of fish selected, the age of the fish (all fully grown), the solution used to make the water acidic and the amount of water in the tank, the water used for each tank, and water temperature and lighting conditions.
- The 5 fish tanks are washed and cleaned. Do not use soap to wash the tank. 1 liter of water is poured into each of the tanks.
- The syringe is used to add vinegar into the 1st tank. After adding a little vinegar a wooden spatula is used to mix the water in the tank. The litmus strips are used to measure the acidity of the water in the tank. More vinegar or water is added to the tank until the pH level reaches 6.5.
- Procedure 3 is repeated until the pH level of the water in tank no. 2 is 6.0, tank no. 3 is 5.5, tank no 4 is 5.0 and tank no. 5 is 4.5.
- Each of the tanks is filled with 10 guppies and the clock is started. The number of guppies still surviving is monitored and recorded every 2 hours for 10 hours and the readings are recorded in the table given below.

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Complexity level:

9

Project cost ($):

50

Time required:

2 hours to prepare, 10 hours for observation

Material availability:

Guppies and tanks can be purchased at a nearby store

Safety concerns:

None

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