Red tides, also called harmful algal blooms (HABs), occur when microscopic algae multiply to higher-than-normal concentrations, often discoloring the water. In Florida and the Gulf of Mexico, the species that causes most red tides is Karenia brevis, a naturally occurring dinoflagellate alga. Karenia brevis produces neurotoxins called brevetoxins that can sicken or kill fish, seabirds, turtles, and marine mammals. These toxins can also affect humans, causing respiratory irritation if aerosolized toxins are inhaled or shellfish poisoning if shellfish contaminated with toxins are consumed. Florida’s tourism-related businesses are particularly affected by Red Tide blooms, as dead marine animals continue to wash ashore, and public health advisories are posted for beach activities and shellfish consumption. The damage to the food chain and the respiratory pollution caused by the smell of large amounts of decomposing marine life discourages tourism and is harmful to the fishing industry.