Sea appear red (red tides) due to

Options

A. Toxins released by Gonyaulax
B. Rapid multiplication of red dianoflagellates
C. Red Pigment, r-phycoerthrin present in red algae
D. All of the above

Answer

**Step-by-Step Solution:**

1. **Understanding Red Tides**: Red tides refer to a phenomenon where coastal waters appear red or brown due to the high concentration of certain microorganisms, particularly dinoflagellates.

2. **Identifying the Organisms**: The specific dinoflagellate responsible for red tides is often Goniolux. These microorganisms can multiply rapidly under certain environmental conditions.

3. **Rapid Multiplication**: The rapid cell division of dinoflagellates leads to a significant increase in their population. This phenomenon is known as algal bloom.

4. **Pigment Production**: As the population of dinoflagellates increases, so does the production of pigments, particularly red pigments. The pigments responsible for the red color in these organisms include R-Picro-Erythrin and carotenoids like beta-carotene.

5. **Visual Effect**: The accumulation of these pigments in large numbers causes the water to appear red, resulting in the phenomenon known as red tides.

6. **Conclusion**: The red appearance of the sea during red tides is primarily due to the rapid multiplication of red dinoflagellates, which produce pigments that color the water.

**Final Answer**: Sea appears red (red tides) due to the rapid multiplication of red dinoflagellates, which produce pigments that color the water.

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