Answer:
Three test
Level of carbon dioxide
Temperature
Nutrient level in water
Step-by-step explanation:
The observer will conduct the following three tests
a) Level of carbon dioxide – The observer will measure the amount of dissolved carbon dioxide which shall in turn determine the extent of photosynthetic activities and the pH level of water. The higher the dissolved CO2, the higher will be the pH and the lower the dissolved CO2, the higher will be the photosynthetic activities
b) Temperature – By observing the temperature, the observer can determine the extent of dissolved oxygen, biological stress, sensitivity to toxic waste and disease and rate of metabolism. The higher is the temperature, the higher is the rate of metabolism, sensitivity and biological stress and lower is the dissolved oxygen.
c) Nutrient level in water – It is measured to determine the extent of biological activity. The higher is the nutrient level in the water, the higher is the biological activity