Algae blooms are caused by an increase in the concentration of one or many types of algae in the water column. Blooms occur in both fresh and salt water systems. In Florida, this is usually in the warm wet months where both water temperature and nutrient inputs are highest. Stormwater runoff plays a major role in the occurrence of algae blooms by transporting nutrient enriched water to aquatic systems. A major issue with algae blooms is the depletion of oxygen in the water column that can lead to fish kills. Some algae species create toxins. Blooms of these types are classified as harmful algae blooms. During an harmful algae bloom fisheries may have to close due the potential threat of eating contaminated organisms and the overall aesthetics of the affected system are diminished. Red tide is a type of harmful algae bloom.