Phaeocystaceae

Phaeocystis is a genus of algae belonging to the Prymnesiophyte class and to the larger division of Haptophyta. It is a widespread marine phytoplankton and can function at a wide range of temperatures (eurythermal) and salinities (euryhaline). Members of this genus live in the open ocean, as well as in sea ice. It has a polymorphic life cycle, ranging from free-living cells to large colonies.

The ability to form a floating colony is one of the unique attributes of Phaeocystis – hundreds of cells are embedded in a polysaccharide gel matrix, which can increase massively in size during blooms. The largest Phaeocystis blooms form in the polar seas: P. pouchetii in the north and P. antarctica in the south. This intense Phaeocystis productivity generally persists for about a three-month period, spanning most of the summer in the Southern Hemisphere. Phaeocystis-abundant ecosystems are generally associated with commercially important stocks of crustaceans, molluscs, fish and mammals. Phaeocystis may have negative effects on higher trophic levels in the marine ecosystem, and consequent impacts on human activities (such as fish farming and coastal tourism), by forming odorous foams on beaches during the wane of a bloom.