located in marine biome marine algal bloom ENVO ORCID:0000-0002-4366-3088 envoPolar ENVO:01000057 2010-03-16T12:12:30Z EcoLexicon:red_tide red tide A marine algal bloom is a rapid increase or accumulation in the population of algae in a marine system. Typically, only one or a small number of phytoplankton species are involved. Although there is no officially recognized threshold level, algae can be considered to be blooming at concentrations of hundreds to thousands of cells per milliliter, depending on the severity. algal bloom