Harmful algal bloom (HAB) is a natural phenomenon
due to increase in density of microalgal species in the
marine and freshwater environments. This incidence is
not only causing adverse effects to the natural surrounding
environments, but accumulation of algal-origin toxins in
filter-feeding shellfish has caused human food poisoning.
Massive bloom of microalgae also caused fish kills in the
natural or finfishes mariculture by excretion of bioactive
compounds or due to hypoxia/anoxia in the surrounding
environments.