Red tides in warm coastal water develop due to the abundance of

Options

A. dinoflagellates
B. Euglenoids
C. diatoms and desmids
D. slime moulds.

Explanation

**Step-by-Step Solution:**

1. **Understanding Red Tides**: Red tides are phenomena that occur in coastal waters, characterized by a discoloration of the water, often appearing red or brown.

2. **Identifying the Cause**: The primary cause of red tides is the proliferation of certain microorganisms, specifically dinoflagellates.

3. **Characteristics of Dinoflagellates**: Dinoflagellates are single-celled eukaryotic organisms. They are a type of algae that can photosynthesize and possess various pigments, including chlorophylls.

4. **Pigmentation**: The red color associated with red tides is due to specific pigments present in dinoflagellates. One notable pigment is called goniolex, which is responsible for the red coloration.

5. **Multiplication of Dinoflagellates**: Under favorable conditions, such as warm coastal waters, dinoflagellates can multiply rapidly, leading to a high concentration of these organisms in the water, which in turn causes the red tide phenomenon.

6. **Conclusion**: Therefore, the abundance of dinoflagellates, particularly those containing the pigment goniolex, is what leads to the development of red tides in warm coastal waters.

**Final Answer**: Red tides in warm coastal water develop due to the abundance of dinoflagellates.

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