Both macroalgae and microalgae (phytoplankton) are natural and desirable components of aquatic ecosytems.
We think of algal blooms when growth is greater than what is normal in a natural aquatic habitat, which usually occurs in cleared and settled catchments from excessive nutrients and disruption of biological function. Extreme macrolagal growth can completely dominate an estuary or river such as in the Peel Harvey during the late 1980s and in the Oyster and Princess Royal Harbours. Phytoplankton can also dominate and cause ecosystem collapse, as in the Peel Harvey in the 1990s.
The term harmful algal bloom is used for those phytoplankton that sometimes produce toxins that affect either aquatic life, such as fish, or even human health. Surveillance of phytoplankton is undertaken state wide under the department’s Statewide Algal Management Strategy. The Department of Water, in partnership with the Department of Health, has developed a statewide algal bloom response protocol and with the Department of Fisheries a Fish Kill Response protocol.