Microcystis is a toxic cyanobacterium that forms harmful algal blooms (HABs) in temperate and tropical waters throughout the world. The World Health Organization recognizes its impact on ecosystems and its ability to pose a threat to both animal (wild and domestic) and human health. The HAB has been identified in the San Francisco Estuary and has been suggested as a factor leading the dramatic decline in pelagic fish populations in that region.
Microcystis is being cultured to determine what environmental factors affect the growth and toxicity of the bloom. The direct effects of the bloom on copepods and fish are being investigated. Linking the presence of the HAB to declines in fish populations is an important step in managing this cyanobacterium to protect animals, humans and the environment.