Which of the following may cause water blooms

Options

A. Lemna
B. Hydrilla
C. Water hyacinth
D. Planktonic algae.

Answer

To determine which of the given options may cause water blooms, we can analyze each option based on their characteristics and the conditions that lead to water blooms.

### Step-by-Step Solution:

1. **Understanding Water Blooms**:
- Water blooms are rapid increases in the population of algae in water bodies, often caused by nutrient pollution, particularly high levels of nitrogen and phosphorus.

2. **Analyzing the Options**:
- **Lemna**: This is a genus of small floating plants known as duckweed. While it can grow rapidly in nutrient-rich waters, it is not primarily responsible for water blooms.
- **Hydrilla**: This is an aquatic plant that can also thrive in nutrient-rich environments, but it is not classified as an algae and does not typically cause water blooms.
- **Water Hyacinth**: This is another floating plant that can proliferate in polluted waters, but like Lemna and Hydrilla, it is not an algae and does not cause water blooms.
- **Planktonic Algae**: This includes various types of algae, particularly blue-green algae (cyanobacteria), which thrive in nutrient-rich waters and are the primary cause of water blooms.

3. **Conclusion**:
- Among the options provided, planktonic algae are the ones that may cause water blooms due to their ability to rapidly multiply in response to high nutrient levels.

### Final Answer:
- The option that may cause water blooms is **planktonic algae**.

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