Nuisance phytoplankton blooms in coastal, estuarine, and inland waters

Multiple interacting physical, chemical, and biotic factors, in proper combination, lead to the development and persistence of nuisance algal blooms. Upon examining combinations of environmental conditions most likely to elicit nuisance blooms, commonalities and analog situations become more apparent among coastal marine (dinoflagellate‐dominated), estuarine (dinoflagellate‐ and cyanobacteria‐dominated), and freshwater (cyanobacteria‐dominated) ecosystems. A combination of the following hydrological, chemical, and biotic factors will most likely lead to bloom‐sensitive waters: a horizontally distinct water mass; a vertically stratified water column; warm weather conditions, as typified by dry monsoon tropical climates and summer seasons in temperate zones; high incident photosynthetically active radiation (PAR); enhanced allochthonous organic matter loading (both as DOC and POC); enhanced allochthonous inorganic nutrient loading (nitrogen and/or phosphorus); adequate availability of essential metals, supplied by terrigenous inputs or upwelling; underlying sediments physically and nutritionally suitable as “seed beds” for resting cysts and akinetes; algal‐bacterial synergism, which exhibits positive impacts on phycosphere nutrient cycling; algal‐micrograzer (protists and rotifers) synergism, which also enhances nutrient cycling without consumption of filamentous and colonial nuisance taxa; and selective (for non‐nuisance taxa) activities of macrograzers (crustacean zooplankton, larval fish). Nuisance bloom taxa share numerous additional physiological and ecological characteristics, including limited heterotrophic capabilities, high degrees of motility, and toxicity. Given such a set of commonalities, it would appear useful and timely to identify and address generally applicable criteria for deeming a water body “bloom sensitive” and to incorporate such criteria into the design of water quality management strategies applicable to both coastal marine and freshwater habitats.