A harmful algal bloom (HAB) contains organisms (usually algae, hence the name) that can severely lower oxygen levels in natural waters, killing organisms in marine or fresh waters. Some HABs are associated with algae-produced toxins. Blooms can last from a few days to many months. After the bloom dies, the microbes which decompose the dead algae use up even more of the oxygen (generating a "dead zone"), which can create fish die-offs. When these zones of depleted oxygen cover a large area for an extended period of time  neither fish nor plants are able to survive. HABs are induced by eutrophication: an overabundance of nutrients in the water. The two most common nutrients are fixed nitrogen (nitrates, ammonia,  urea) and phosphate.  Harmful Algal Blooms , Center for Disease Control These nutrients are emitted by agriculture, other industries, excessive fertilizer use in urban/suburban areas and associated urban runoff. Higher water temperature and low circulation are contributing factors. HABs can cause significant harm to animals, the environment and economies. They have been increasing in size and frequency worldwide, a fact that many experts attribute to global climate change. The U.S. National Oceanic and Atmospheric Administration (NOAA) predicts more harmful blooms in the Pacific Ocean.
A harmful algal bloom (HAB) contains organisms (usually algae, hence the name) that can severely lower oxygen levels in natural waters, killing organisms in marine or fresh waters. Some HABs are associated with algae-produced toxins. Blooms can last from a few days to many months. After the bloom dies, the microbes that decompose the dead algae use up even more of the oxygen (generating a "dead zone"), which can cause fish die-offs. When these zones of depleted oxygen cover a large area for an extended period of time , neither fish nor plants are able to survive. HABs are induced by eutrophication: an overabundance of nutrients in the water. The two most common nutrients are fixed nitrogen (nitrates, ammonia, and urea) and phosphate. cite web URL |title= Harmful Algal Blooms |publisher=CDC These nutrients are emitted by agriculture, other industries, excessive fertilizer use in urban/suburban areas and associated urban runoff. Higher water temperature and low circulation are contributing factors. HABs can cause significant harm to animals, the environment and economies. They have been increasing in size and frequency worldwide, a fact that many experts attribute to global climate change. The U.S. National Oceanic and Atmospheric Administration (NOAA) predicts more harmful blooms in the Pacific Ocean.
R
which
that
R
create
cause
A
,
A
and
A
cite web URL |title=
R
, Center for Disease Control
|publisher=CDC