Phytoplankton are microscopic plants that form the base of the food chain in the ocean.
The most well-known aspects of phytoplankton studies are those relating to the “Red Tides” that have occurred. “Red Tide” is the name given to the phenomenon in which a population explosion or “bloom” takes place in a phytoplankton population. This usually results in the discoloration of the water, which may be tinged with red (although other colours can be produced, depending on the pigmentation of the microscopic plants). The environmental and economic implications of certain species of phytoplankton have stimulated extensive research over the years. Some species contain toxins, which can become concentrated in filter-feeding animals such as mussels. Severe consequences can arise when humans eat contaminated shellfish. Many species are also responsible for fish kills around the world. Species of special interest are Karenia mikimotoi (Gyrodinium aureolum), Dinophysis acuminata and D. acuta, as they have been responsible for some outbreaks around south-west Ireland.