Due to the constant battle of phytoplankton, the diversity of species in algal blooms is extremely high and, each day, a new dominant species comes out on top.
Source: Microorganisms Battle It Out Daily Within Algal Blooms
Let me suggest to everybody out there that this happens not only in marine environments laughing.
I have dozens of clients and every single one at this point is clear and not green but when I get a new client whose pond is green I have to tell them repeatedly that there are thousands of different species of algae and just because the pond looks green does not mean that it’s not progressing through cycles. (unless the owner keeps changing things and putting everything back several months :-)) My goals are to set up an old growth ecology and we have to get through the weeds first.