The effect of fertilizing a fish pond with compost manure on phytoplankton popul...

This question is asking about the effect of fertilizing a fish pond with compost manure on the phytoplankton population and fish yield. Phytoplankton are microscopic plants that float in bodies of water and serve as a food source for fish. Fish yield refers to the amount of fish that can be harvested from a pond.

The correct answer is Option B: Phytoplankton population decreases while fish yield increases.

When compost manure is added to a fish pond as fertilizer, it provides nutrients that stimulate the growth of phytoplankton. As the phytoplankton population increases, more food becomes available for the fish. This leads to an increase in the fish yield, as there is now a greater food source to support their growth and reproduction.

However, as the fish consume the phytoplankton, the population of phytoplankton decreases. This is because the fish are eating the phytoplankton for food. As the phytoplankton population decreases, the fish yield continues to increase because the fish have an abundant food source.

In summary, when compost manure is used as fertilizer in a fish pond, the phytoplankton population initially increases due to the added nutrients. This increase in phytoplankton leads to an increase in fish yield. However, as the fish consume the phytoplankton, the population of phytoplankton decreases while the fish yield continues to increase.

It is important to note that this relationship between phytoplankton population and fish yield can vary depending on the specific conditions of the pond and the type and amount of fertilizer used. Different fertilizers may have different effects on the phytoplankton and fish populations.