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Microcystis Blooms. Causes, Problems, and Solutions By Bernie Coates. What is it?. Microcystis is a blue-green algae (cyanobacteria) commonly found in nutrient rich freshwater. Its blooms are being found more frequently and its associated toxins are cause for worldwide concern. Causes.

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microcystis blooms

Microcystis Blooms

Causes, Problems, and Solutions

By Bernie Coates

what is it
What is it?

Microcystis is a blue-green algae (cyanobacteria) commonly found in nutrient rich freshwater. Its blooms are being found more frequently and its associated toxins are cause for worldwide concern.


Microcystis blooms are usually caused by eutrophication (nutrient enrichment) of the water body. Typically the limiting nutrient is phosphorous. Blooms can be encouraged by:

  • Fertilizer runoff from fields, golf courses, and urban lawns
  • Untreated, or partially-treated, domestic sewage
  • Liberation of phosphorous from the lake or pond bottom under reducing conditions
  • The presence of Microcystis can actually increase the liberation of phosphorous from the sediments thereby accelerating bloom growth (Xie, Xie, & Tang, 2000).
some microcystis blooms
Some Microcystis Blooms

Photo from Experimental Lakes Area in Manitoba, Canada

  • Microcystis contain toxins known as microcystins. These toxins can cause fish kills and in some instances have resulted in human casualties.
  • There are several other cyanobacteria species that produce microcystins including:
  • Anabaena
  • Oscillatoria
  • Nostoc
  • Hapalosiphon
  • Anabaenopsis

Microcystins are hepatotoxins.

  • Acute toxicity is the main concern with Microcystins. The compound attacks the liver causing hemorrhaging and liver failure.
  • The threat to human health is of great concern since long-term exposure to relatively low doses could encourage the development of liver tumors.


  • In February 1996 sixty patients with kidney failure died and 66 others were rendered ill in a hemodialysis clinic in Caruaru, Brazil, when untreated turbid water contaminated with Microcystis was used for dialysis during a water shortage.
  • A large epidemic in Brazil involving human deaths occurred in 1988. Over 2,000 residents suffered from gastroenteritis over an 8-week period, with 88 deaths. An epidemiologic investigation implicated drinking water from a reservoir, even water that had been boiled before use. Infectious agents, metals or toxins were not found; however, the cyanobacterium genera Anabaena and Microcystis were found in great quantities in untreated water from the reservoir. Algal toxins were not assayed, but the circumstantial evidence strongly implicated the cyanobacteria as the cause.
chemical solutions
Chemical Solutions
  • Limit influx of nutrients to the water by more efficient fertilizer application techniques.
  • Dredging lakes and ponds where there are high amounts of phosphorous tied up in the sediments.
  • Application of aluminum sulphate and copper sulfate in combination (Hullebusch, Delutat, Chazal, & Baudu, 2002) .
non chemical solutions
Non-chemical Solutions
  • Non-chemical means of control was achieved using barley straw extract made from decomposed barley straw. Experiments produced a 10-fold decrease in Chlorophyll a levels (Ball, Williams, Vincent, and Robinson, 2001) .
  • Ultraviolet (UV) radiation in small doses prior to bloom development inhibits reproduction. Additionally, UV increases the specific gravity of the cells thereby limiting their ability to remain in suspension, which effectively stops the Microcystis from photosynthesizing (Alam, Otaki, Furumai, & Ohgaki, 2001).
other solutions
Other Solutions
  • Bank filtration
  • Ozonation
  • Reverse osmosis
  • Activated carbon treatment

Xie, L.Q., Xie, P., & Tang, H. Enhancement of dissolved phosphorous release from sediment to lake water by Microcystis blooms—an enclosure experiment in a hyper-eutrophic, subtropical Chinese lake. Environmental Pollution. 2003;12:391-399.

Hullebusch, E., Deluchat, V., Chazal, P., & Baudu, M. Environmental impact of two successive chemical treatments in a small shallow eutrophied lake: Part I & II. Case of aluminum sulphate. Environmental Pollution. 2002;120:617-634.


Ball, A., Williams, M., Vincent, D., & Robinson, J. Algal growth control by a barley straw extract. Biosource Technology. 2001;77:177-181.

Alam, M., Otaki, M., Furumai, H., Ohgaki, S. Direct and indirect inactivation of Microcystis aeruginosa by uv-radiation. Wat. Res. No. 4. 2001;35:1008-1014.

yukio yamada

Yukio Yamada

A Leader in Phycology in Japan: Considered to be the founder of modern Japanese phycology

yamada s background
Yamada’s Background
  • Born in 1900 in Kyoto Japan
  • Entered Daiichi High School in 1918
  • In 1921, Yamada entered the Botanical Institute of the Faculty of Science at the Imperial University of Tokyo
  • Professor Bunzo Hayata convinced Yamada he should study algae
positions held
Positions Held
  • Professor of Taxonomic Botany for the Faculty of Science at Hokkaido University in Sapporo
  • First director of the Institute of Algological Research
  • Member of the University Senate and Dean of the Faculty of Science at Hokkaido University
  • Founded and served as president of the Japanese Society of Phycology
  • President of the International Phycological Society
primary contributions
Primary Contributions
  • Detailed taxonomic, morphological and floristic accounts of red, brown and green algae from Japan
  • Described nearly 200 new taxa of marine algae
  • Floristic Studies of marine algae from Taiwan
  • Life history studies of various marine algae, especially Chlorophyta
  • Mentor for almost 50 graduate students


Garbary, David J., and Michael J. Wynne, eds.

Prominent Phycologists of the 20th Century.

Hantsport, Nova Scotia: Lancelot Press Ltd.,1996.