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Blue-Green Algae and Harmful Blooms

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Blue-green algae, or cyanobacteria, or blue-green algae, are a form of bacteria. These algae are thought to be among the first life forms on Earth. They may also be colors other than blue or green. They are very common and may be found naturally in marine and freshwater environments. Blue-green algae are conduct photosynthesis and nitrogen fixation. Nitrogen fixation occurs in specialized cells called heterocysts.

In California, certain forms of blue-green algae have been a particular problem in the Klamath River watershed and on the Central Coast. Blooms of these bacteria can poison livestock, wildlife and humans through the production of cyanotoxins. Certain other nontoxic forms can impart an unpleasant taste to water, and fish. They also give off an unpleasant smell as they die off and decay.

Marine Algae

Phytoplankton are microscopic, single-celled organisms at the base of the food chain in both freshwater and marine environments. Phytoplankton are primarily autotrophic. They contain chlorophyll and require sunlight to conduct photosynthesis to live and grow. Approximately, half the air we breathe originates from marine phytoplankton. Most phytoplankton are buoyant and inhabit the upper part of the ocean, where sunlight still penetrates the water. Phytoplankton also require inorganic nutrients such as nitrates, phosphates, and sulfur which they convert into proteins, fats, and carbohydrates.

Dinoflagellates or diatoms are the two main classes of phytoplankton in marine waters. Dinoflagellates use a whip-like tail, or flagella, to move through the water and their bodies are covered with complex shells. Diatoms also have shells, but their structure is rigid and made of interlocking parts. Diatoms do not rely on flagella to move through the water and instead rely on ocean currents to travel through the water.

Harmful Algal Blooms

In a balanced ecosystem, phytoplankton provide a food base for many organisms. There are hundreds of varieties of phytoplankton, and most are harmless. When there is an oversupply of nutrients and ideal physical conditions, phytoplankton can have high growth rates and form algal blooms. Algal blooms can cause enormous, smelly blooms covering miles of ocean and coastal waters. These blooms include so-called red and brown tides, so named because of the color of the phytoplankton seen on the surface. These outbreaks can decimate large areas by robbing the water of oxygen through decomposition and suffocating life forms found there.

An algal bloom which threatens or damages the environment, human health or surrounding economies is considered a Harmful Algal Bloom, or HAB. Certain varieties can form toxins that may be accumulated by fish and shellfish, which can then pass the toxins on to humans or marine wildlife which eat those creatures. Some of these harmful toxins include domoic acid, paralytic shellfish poisoning, and cyanotoxins. That poisoning can become evident in humans as stomach and respiratory problems, brain damage or paralysis. Occasionally, depending on the specific algal species, the results can be fatal. In some cases contact can cause human respiratory and skin problems.

The Water Boards and Algal Blooms

The Water Boards regulate the nutrients in manmade runoff that contribute to bloom development. We have a responsibility to maintain standards to protect water quality and beneficial uses. We do so by regulating point and nonpoint source dischargers through permits or other enforceable requirements.

For example, the State Water Board sets water quality objectives for the Ocean in the California Ocean Plan. The Ocean Plan algal bloom objectives include requirements that discharges will not cause undesirable discoloration of the ocean surface, objectionable or dangerous growths (blooms) or concentrate organic materials in seafood at levels dangerous to humans. These objectives are then translated into requirements placed in discharge permits for facilities like wastewater treatment plants and storm drains.

In addition, the Water Boards support research and monitoring to better understand algal blooms. The Water Boards work with the State Department of Public Health and the county health departments to post contaminated water bodies when blue green algal blooms pose a health threat.

Blue-Green Algae in Klamath River Basin

The U.S. Environmental Protection Agency and the State Water Resources Control Board sponsored an informational workshop on blue-green algae (BGA) during November 2005. The workshop provided an opportunity to learn more about this summer's blue-green algae bloom in the Klamath Basin, to hear from national and Oregon experts on cyanobacteria, and to learn more about BGA issues elsewhere in California.

More Information

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Staff Contact

Johanna Weston - email: Johanna.Weston@waterboards.ca.gov; phone: (916) 327-8117