Water blooms are mainly formed by

Options

A. Protozoa
B. Planktonic blue green Algae
C. Slime moulds
D. Lemna and Hydrilla

Answer

### Step-by-Step Text Solution:

1. **Understanding Water Blooms**: Water blooms, commonly referred to as algal blooms, occur when there is a rapid increase in the population of algae in water bodies.

2. **Causes of Algal Blooms**: The primary factors contributing to algal blooms are the presence of excess nutrients, particularly phosphorus and nitrogen. These nutrients often come from agricultural runoff, sewage discharge, and industrial waste.

3. **Role of Nutrients**: When phosphorus and nitrogen enter the water, they act as fertilizers for algae, promoting their rapid growth.

4. **Impact on Aquatic Life**: As algae proliferate, they can deplete the oxygen levels in the water, leading to hypoxic conditions. This lack of oxygen can be detrimental to aquatic animals, particularly fish, which may die as a result.

5. **Eutrophication**: The process of algal blooms leading to oxygen depletion and the subsequent death of aquatic life is known as eutrophication. This can severely affect the ecosystem of the water body.

6. **Conclusion**: Therefore, water blooms are mainly formed by algae, specifically due to the excess nutrients (phosphorus and nitrogen) in the water.

### Final Answer:
Water blooms are mainly formed by **algae**, particularly due to the excess nutrients like phosphorus and nitrogen.

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