Blue-Green Algae ( Cyanobacteria)

These ancient microscopic organisms, sharing the characteristics of both algae and bacteria, are abundant and exist naturally in both fresh and salt water. When phosphorus and nitrogen are abundantly present in the right proportions (see eutrophication) and weather conditions are warm, blooms of cyanobacteria may occur. The blooms may cause taste and odor problems in water and produce poisons. Blue-green algae growing in fresh water need nitrogen and phosphorus to grow. The presence or absence of available phosphorus can stimulate or limit their growth.