Subject: toxic algae/ King County Lakes
Date: Sep 24 12:38:59 1997
From: "Li, Kevin" - Kevin.Li at metrokc.gov


>
>
>FYI,
>This is text from a web page report on the recent toxic algae bloom in Lake
>Sammamish. The web page also has information on the August longfin smelt kill
in Lake Washington, as well as background information and data on King
>County lakes and water quality.
>
>Check out our lakes web page!
>http://waterquality.metrokc.gov/waterres/lakes/index.htm
>
>Kevin Li
>King County Environmental Lab
>322 W. Ewing St.
>Seattle, WA 98119-1507
>
>kevin.li at metrokc.gov
>
>
>Toxic Algae in Lake Sammamish!
>------------------------------------------------------------------------
><Picture>These large green clumps are part of the algae bloom in Lake
>Sammamish.
>
>On Friday September 19, King County limnologist Jonathan Frodge (206
>296-8018) responded to a call from Joanna Buhler about an algae bloom on Lake
>Sammamish. While not all of the lake was surveyed, an extensive algae bloom
>extended along much of the south shore of the lake and has been reported on
>the west side about two-thirds of the way up the lake. The bloom began on
>Thursday and is continuing today (Monday 9/22). The swimming area of Lake
>Sammamish State Park had sufficient algae to tint the water a bright green
>and extensive surface film was present at the beach. A grab sample of this
>surface bloom was collected from within the swimming area of the park and on
>Saturday was carried to Dr. Michele Crayton (253 535-7547) , an algal
>toxocology expert at Pacific Luthern University. The cyanobacteria blooming
>in the lake is primarily Microcyctis aeruginosa and tested positive for
>toxicity. Cyanobacteria blooms are tested for toxicity using a mouse bioassay
>similar to the one used for detecting "red tide" toxins found in marine
>environments. Using this test, the relative toxicity of the Microcystis bloom
>in Lake Samamish was considered to be high. The greatest risk is to small
>children and pets which require a smaller dose of the toxin to be harmful.
>Lake residents and visitors are cautioned to keep children and pets out of
>any area containing a bloom until the bloom has disappeared completely.
>
><Picture>Algae bloom in a swimming area in Lake Sammamish State Park.
>
>Cyanobacteria, formerly called "blue-green algae", are relatively simple,
>primitive life forms closely related to bacteria and should not be mistaken
>for true algae. Cyanobacteria are found throughout the world in terrestrial,
>freshwater and marine habitats. However, it is the freshwater habitat that
>typically experiences a cyanobacteria "bloom". Nutrient-rich bodies of water
>such as eutrophic lakes, agricultural ponds, or catch basins, may support a
>rapid growth of cyanobacteria. When conditions are good, a "clear" body of
>water can become very turbid with a green, blue-green or reddish-brown growth
>within just a few days. Many species can regulate their buoyancy and float to
>the surface to form a thin "oily" looking film, or a blue-green scum several
>inches thick.
>
><Picture>A close-up of the cyanobacteria.
>
>
><Picture>Microcystis magnified 100 times under a microscope.
>
>Sometimes blooms may produce toxins that are potentially lethal to animals,
>including humans. Two genera of cyanobacteria account for the vast majority
>of toxic blooms world-wide: Microcystis and Anabaena. Toxin producing
>versions of both genera have been documented in Washington state. Microcystis
>is known to produce a family of toxins called "microcystins". Named after
>this genus, they are heptapeptides that primarily affect the liver in animals
>(hepatotoxins). More recent experimental evidence shows that these toxins may
>also act as liver tumor promoters in extremely small amounts. A tumor
>promoter does not initiate cancer formation but helps a previously developed
>cancer to survive. This type of toxin has been shown to persist in water for
>a week or more after the bloom has disappeared. Poisoning symptoms may take
>30 minutes to 24 hours to appear, depending upon the size of the animal
>affected and the amount of toxic bloom consumed. Microcystin toxicosis may
>include jaundice, shock, abdominal pain/distention, weakness,
>nausea/vomiting, severe thirst, rapid/weak pulse and death. No human deaths
>have been attributed to poisoning by cyanobacteria.
>
>
>
>------------------------------------------------------------------------
>
>For questions and concerns please contact:
>
>Jonathan Frodge
>jonathan.frodge at metrokc.gov
>King County Water and Land Resources
>(206) 296-8018
>
>
><Picture>Back to Lakes Monitoring Home Page
>