Novel and nuisance phytoplankton blooms in the sea : evidence for a global epidemic

Evidence is presented from the Baltic Sea, Kattegat, Skagerrak, Dutch Wadden Sea, North Sea, Black Sea, Tolo Harbour (Hong Kong) and Seto Inland Sea that a long-term trend in increased frequency and dynamics of novel phytoplankton blooms of indigenous species, both benign and harmful ones, has accompanied nutrient enrichment of coastal waters and inland seas on a global scale. Anthropogenic enrichment of nitrogen and phosphorus has led to long-term declines in the silicate:nitrogen and silicate:phosphorus ratios. It is suggested that the decline in silicate:nitrogen ratio has particularly favored non-diatom blooms in response to nutrification, and such ionic ratio regulation within nutrification is a key factor associated with the global epidemic of novel phytoplankton blooms and phylogenetic shifts in biomass predominance in the sea. A feature independent of the global bloom epidemic is the apparent global spreading of certain species, some of which exhibit blooms. Local stimulation of the indigenous hidden flora to detectable levels may also be increasing.