This species is a vertical migrator, usually occurring in surface waters during the day and at depth during the night. Chains of cells apparently become lodged between secondary lamellae in the fish gills and cause blood hypoxia as a result of mucus production. These diatoms may be restricted to near-surface waters or mixed throughout the water column depending on local hydrographic conditions. Most fish growers have their own phytoplankton monitors who sample at the pen sites on a daily basis from April through September. They also rely on reports from other phytoplankton monitoring programs.
Economic losses are about half a million dollars per event.