On the global increase of harmful algal bloom

Abstract

Harmful algal blooms have occurred throughout recorded history, but during the past two decades the human health and economic impacts of such events have increased in frequency, intensity, and geographic distribution. To some extent, this simply reflects our increased awareness of toxic species and the enormous expansion in aqua culture efforts. Evidence is accumulation, however, that human activities contribute significantly to this increase through the stimulation of exceptional blooms by cultural eutrophication (e.g. from domestic, industrial and agricultural wastes, acid precipitation, deforestation and increased land run-off) and by the spreading of nuisance organisms in ships’ ballast water. The global nature of these phenomena is illustrated with examples drawn from Japan, North America, Europe, South-East Asia and Australia, and involving species of dinoflagellates, diatoms, prymnesiophytes, raphidophytes and cyanobacteria.