Blue-Green Algae
What
are blue-green algae?
Many algal species are found in
Wisconsin
waterways. Algae act like other plants and convert sunlight into energy,
forming the base of a lake’s food chain. Algae are eaten by zooplankton, which are in turn eaten by small
fish, then larger fish, and eventually the larger fish are eaten by birds,
shore animals, and people. True
algae are a vital part of lake ecosystems
But blue-green algae are not true algae. They are photosynthetic bacteria known as
cyanobacteria
which can cause illness and death in humans and animals. While they can convert sunlight into energy, they are not as
important a part of the food chain since most aquatic organisms prefer not
to eat them.
Although a nuisance and potential health hazard,
blue-green algae are a natural part of lake ecosystems and one that has
been around for a long time. Today,
while scientists know more about blue-green algae, they are still learning
about the health risks to humans.
Announcement-New Program in 2009
The Bureau of Environmental and Occupational Health in the
Wisconsin Division of Public Health is working with the Centers for
Disease Control and Prevention to maintain a Harmful Algal Bloom (HAB)
Surveillance Program. This program will collect information about human
and animal illness and death resulting from exposure to blue-green algae.
This information will provide a better understanding of the public health
problem posed by algae blooms in our lakes and rivers and enhance efforts
to prevent exposures from occurring.
Program staff are asking the public to notify them of any known or
suspected human or animal exposures to blue-green algae that may have
resulted in illnesses. Animal exposures can include pets, livestock or
wildlife such as birds and fish. Researchers will collect information
about symptoms and any treatment received. They will also collect exposure
information such as date and location, and may collect water samples for
analysis.
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To report an illness, click on the “Report
A Case” button to the right.
You will be asked to provide your contact information and a
brief description of what happened.
A public health official will then get in touch with you as
soon as possible. |
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No single agency has the resources or mandate to address the
problem of harmful algal blooms, therefore a key goal for the HAB program
is to develop relationships with partners and stakeholders so data can be
collected and shared so that a coordinated effort occurs. Because this
program does not provide treatment services for algal bloom related
illnesses, individuals experiencing severe symptoms should seek medical
attention immediately.
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can blue-green algae make me sick?
There are many species of blue-green algae found in
Wisconsin
lakes and waters and certain species can produce toxins.
Different species produce different toxins and many species
produce more than one type. Each
toxin can affect your health differently: neurotoxins
affect your central nervous system, hepatotoxins cause liver damage
and exposure to bloom material can affect your skin and
gastrointestinal system. Your
symptoms depend on which toxin and how much of it you are exposed
to, and how you are exposed.
How
can I be exposed to blue-green algae?
You can be exposed to blue-green algae by accidentally
swallowing water with algal toxins, by skin contact with algae, and
by inhaling aerosolized water droplets that contain algal toxins.
Swallowing water poses the biggest risk of exposure to a
large quantity of toxins and can lead to mental confusion, nausea,
vomiting, diarrhea, liver failure, paralysis, and possibly death.
Skin contact with algae can cause a painful rash or
blistering. As motor
boats, waves, and other events splash water into the air, some water
molecules get aerosolized and carried on the wind.
Very small amounts of algal toxins can be inhaled by people
in boats or on the shoreline of the lake.
This can cause coughing, irritation of the nose and throat,
watery eyes, runny nose, headache, and other allergy-like symptoms.
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How
can I tell if toxins are present?
Not all algal blooms produce toxins.
And even if a blue-green algae bloom is present, it may not
be producing toxins or producing enough toxin to cause a health
concern. Larger algal
blooms have the potential for higher concentrations of toxin.
Unfortunately, there is no immediate way to know if an algal
bloom is dangerous or not. It
takes at least several days for a laboratory to analyze a water
sample to see if toxins are present.
During that time, a harmless algal bloom may become more
toxic, a toxic algal bloom may become harmless, or the bloom could
blow away or dissipate all together.
This is what makes it so difficult to know when it is
appropriate to close a beach. By
the time the analysis is done, the conditions may have changed.
And during the time it takes to process the analysis, other
people may be exposed to potentially hazardous conditions.
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What
are algal blooms and when do they occur?
When environmental conditions are right, the algal population
can grow quickly and a bloom can occur.
A bloom is a sudden increase in algae cells in a certain area
of water. Little wind, warm water, sunlight, and plentiful nutrients
–especially phosphorus- all favor the chances that a bloom will
occur. Warm weather
patterns and large rain events that wash agricultural and
residential fertilizers into the water can also jump start a bloom.
In
Wisconsin, blooms typically occur during the warm weather months between mid
June and mid September.
Waters can become cloudy with rapidly reproducing microscopic
algae. Blue-green algae
will follow sunlight and nutrients by floating to the surface where
they can form thick scum layers or mats and the surface may look
bubbly or frothy. These
can be carried to different locations by wind or tide.
When blue-green algae are present, the algal scum can be a
variety of colors such as fluorescent blue, green, white, red or
brown. And more than one
color may be present in the same bloom.
It may look like thick paint floating on the water.
Frequently, these blooms give off a foul odor.
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What
should I do if I see a bloom?
People should use common sense when dealing with algae.
The safest thing to do is to treat
every algal bloom as though it were potentially harmful.
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PEOPLE |
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Do not swim or wade through algae.
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Do not boat, water ski or jet ski over algal
blooms.
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Do not fish in algae-laden waters.
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Always shower off with soap and water after
swimming in a lake.
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PETS |
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Do not let dogs drink lake
water during an algal bloom
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Do not let dogs eat algal
scum, or lick it off their fur.
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If your dog has been exposed
to algae, wash it off with clean water immediately.
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What
should I do if I’m exposed to blue-green algae?
If you or your pet have been exposed to algae and are experiencing
severe symptoms, such as those that result from ingestion of blue-green
algae, seek medical attention immediately.
For immediate 24 hour, toll free information and advice about
possible exposures to blue-green algae, contact the Wisconsin
Poison Center at 1-800-222-1222. Always shower off with soap and water
after swimming in lakes and rivers. If
you are suffering from symptoms associated with inhaling aerosolized water
droplets, get to fresh air away from the exposure source.
For a printable fact sheet on blue-green algae: DHS
Basic
Information (PDF, 85.8kb)
Links
(exit DHS)
Wisconsin
Poison
Center:
http://www.wisconsinpoison.org/
or
call 1(800)222-1222
Wisconsin
Department of Natural Resources
blue-green algae website:
http://dnr.wi.gov/lakes/bluegreenalgae/
Centers for Disease Control and Prevention
(CDC) HABISS program website:
http://www.cdc.gov/hab/
World
Health Organization (WHO)
cyanobacterial toxins website:
http://www.who.int/water_sanitation_health/diseases/cyanobacteria/en/
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Keep our lakes clean!
Minimize the use of lawn fertilizers.
Don’t use phosphate-containing fertilizers.
Maintain septic systems.
Plant natural vegetation around ponds and lakes to filter
incoming water.
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For more information about the Bureau of Environmental and Occupational
Health programs, call (608) 266-1120.
Back to Environmental Health Resources
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