Hi,

Yes, it called as Red Algae due to a red pigment, called peridinin , which collects light during photosynthesis , colors the water red when large numbers of the plankton populate an area.

Gonyaulax, genus of dinoflagellate algae (family Gonyaulacaceae) that inhabit marine, fresh, or brackish water. Several planktonic species are toxic and are sometimes abundant enough to colour water and cause the phenomenon called red tide, which may kill fish and other animals.

Dinoflagellates were classified under kingdom Protista and phylum.

Hope this helps.