A student recently sent an e-mail to TPW asking for information on red tide for a class report. Here is the response sent by Andy Tirpak of the TPW Clear Lake office. Let me begin to answer your request by giving you some information on harmful algal blooms.
Harmful algae are microscopic, single-celled plants that live in the sea.
Most species of algae or phytoplankton are not harmful and serve as the energy producers at the base of the food web, without which higher life on this planet would not exist. When temperature, salinity, and nutrients reach certain levels, a massive increase in Gymnodinium breve algae occurs. No one knows the exact combination of factors that causes red tide, but some experts believe high temperatures combined with a lack of wind and rainfall are usually at the root of red tide blooms. Toxins from the red tide algae in the water or in wind-blown ocean spray can irritate lungs, eyes, nose and throat and cause respiratory irritations. The toxins can enter the food chain when filter-feeding shellfish like clams and oysters ingest the algae and retain the toxins in their tissues.