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Cyanoblooms” refer to massive accumulations of subsurface cyanobacteria sufficiently shallow to be visible from a viewpoint above the surface.  Specifically they refer to neustonic accumulations from the buoyant cells, filaments, and colonies of the cyanobacteria.  Surface accumulation is accelerated during windless days.  Low velocity wind (< 5 km h-1) causes leeward accumulation (image 3 above), while strong wind turbulence drives cyanobacteria downward.  Heterogeneous “patchy” distribution can result from localized wind and water currents (image 8 above).

"Deep" (metalimnetic layers) cyanobacteria become buoyant under conditions of limiting nutrients (usually phosphorus), and benthic mats accumulate metabolic gases that increase their buoyancy.  Such mechanisms also form blooms.

“Harmful algal blooms (HABs)” usually refer to toxins produced by cyanobacteria (“Harmful Cyanoblooms”) and other bloom-forming photosynthetic protists (“algae”),– such as toxic diatoms, dinoflagellates, prymnesiophytes.

Blooms can also be formed by chlorophyceae (green “algae”) as well as diminutive macrophytes (Wolffia, Lemna, Azolla, Salvinia) and superficially be mistaken for HABs.