Question 4. Find out what do the terms ‘algal bloom’ and ‘red-tides’ signify.

Answer: Dianoflagellates can be of different colours depending on the type of pigment present. The red dianoflagellate sometimes multiply at a very rapid rate. This is called as algal bloom. This gives a red appearance to the part of affected sea. This is also known as ‘red tide’. Toxins released by them can kill other marine species.