Blue-green Algae Frequently Asked Questions

http://www.dep.state.fl.us/water/bgalgae/faq.htm[10/31/2010 8:50:46 AM]

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Blue-green Algae Quick Links

Frequently Asked Questions

What is blue-green algae?

What causes blue-green algae blooms?

Are the blue-green algae blooms a new problem?

How long do the blooms last?

Can blue-green algae blooms be treated?

Are large blue-green algae blooms harmful to

lake/river ecosystems and cause fish kills?

What is the state doing about the blue-green algae

blooms?

Whom can I contact to report a blue-green algae

bloom or to get more information about water

quality?

Are there web sites for more information about blue-green algae?

What is blue-green algae?

Blue-green algae, or “cyanobacteria,” are natural to the environment’s food chain and are found all

over the world. They are actually a type of bacteria but, like plants, they can use sunlight to grow.

Many live with other types of algae and microscopic animals, collectively termed “plankton.”

Blue-green algae are a group of organisms that are among the oldest on the planet. They are

ubiquitous - found in marine waters as well as freshwater and brackish habitats. Blue-green algae are

also common in other states, including Georgia, Texas, Alabama and Michigan.

Some – not all – blue-green algae can produce toxins that can contribute to environmental

problems and affect public health. Those blue-green algae that are known to produce toxins do not

always do so. Little is known about exactly what environmental conditions trigger toxin production.

Blooms can float on the surface and be several inches thick or they can lie below the surface of the

water. Blooms can disappear from view or move to different parts of a pond or lake.

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What causes blue-green algae blooms?

Blue-green algae multiply quickly in water bodies with high nutrient levels such as phosphorous or

nitrogen, and particularly when the water is warm and the weather is calm. That's why blue-green

algae are most common in Florida in the summer and early fall, with its high temperatures and

abundant sunlight, although they can occur at any time.

Waters that flow slowly with low turbulence – such as impounded rivers, dams, or water storages –

are at particularly high risk of algal blooms.

Blue-green algae growth can become seemingly explosive when lots of nutrients are present,

providing a rich feast that can then cause “blooms” that may look like floating carpets of blue-green

algae turning the water green. Many other states, and countries for that matter, are experiencing

problems with algal blooms.

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Are the blue-green algae blooms a new problem?

Algal blooms are not a new phenomenon. Algal blooms were documented in Florida’s coastal waters

as early as the 19th century. However, increased nutrient loading in our waterways has likely

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Blue-green Algae Frequently Asked Questions

http://www.dep.state.fl.us/water/bgalgae/faq.htm[10/31/2010 8:50:46 AM]

contributed to increased frequencies of blooms in our freshwater systems.

In 1998, recognizing the need to assess the status of toxic microalgae in Florida, the state legislature

approved funds to the Florida Harmful Algal Bloom Task Force (FLHABTF) to address any potential

concerns regarding microalgae, including blue-green algae. Collaborative studies funded by the

FLHABTF were initiated between the St. Johns River Water Management District, the Florida Fish and

Wildlife Conservation Commission’s Fish and Wildlife Research Institute, Florida Department of Health

(DOH), private laboratories, and Wright State University to investigate the distribution of toxic bluegreen algaeand their toxins (cyanotoxins) in Florida waters. For more information on this topic,

please visit HAB Task Force Blue-Green Algae Studies.

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How long do the blooms last?

Blooms can last days, weeks or months, depending on conditions. Scientists cannot predict when or

where blooms will occur or how long they will last; the blooms run their course and dissipate

naturally.

Can blue-green algae blooms be treated?

No. The Florida Fish and Wildlife Conservation Commission does not recommend treatment because it

may release the toxins.

The Bureau of Invasive Plant Management does not favor, and does not issue permits for, the

application of algaecides to treat blue-green algal blooms in surface waters of the state. Such

treatments are generally not very effective and would need to be repeated frequently, potentially

resulting in unacceptable levels of algaecide in surface water bodies.

Surface water bodies used as drinking water reservoirs may be treated on occasion by water

treatment plants in some counties. These treatments are exempt from permit requirements related to

the application of algaecides in surface waters of the state.

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Are large blue-green algae blooms harmful to lake/river ecosystems and cause fish kills?

Blooms of blue-green algae that last more than a few months can be harmful to lake/river

ecosystems and cause fish kills because of the decrease in oxygen levels and direct ingestion in the

food chain:

 Persistent blooms block sunlight that feeds plants growing on the bottom of lakes, resulting in the

loss of rooted aquatic vegetation, which is valuable fish habitat. Intense blooms can cause

extreme fluctuations in daytime and nighttime water oxygen levels, due to the oxygen produced

during the daytime photosynthesis and the oxygen consumed during the nighttime respiration. The

nighttime respiration as well as the decay of the blue-green algae, can consume much of the

oxygen in the water, causing fish to die.

Algae use sunlight to make food and are eaten by microscopic animals (zooplankton). Small fish

eat the zooplankton, and larger fish and other large animals eat the small fish. However, bluegreen algae are often difficult to eat or are of poor nutritional value for zooplankton. Consequently,

zooplankton, particularly types that are the best fish food, often decline during blooms. This

decline can impact the number of desirable game fish. 

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What is the state doing about the blue-green algae blooms?

As part of our mission and responsibilities, the state – including Florida Department of Environmental

Protection, Florida Fish and Wildlife Conservation Commission, Florida Department of Health, St.

Johns River Water Management District, South Florida Water Management District-and the University

of Florida is responsibly concerned, not alarmed, about the current situation as we continue to

monitor, evaluate and provide information to other concerned local, county, state and federal

agencies.

The state is looking to increase the frequency and expand some of its current routine algal bloom

monitoring in the major water bodies to try and get a better understanding of the phenomenon. This

information will be shared with our government partners and the public as it becomes available.
Blue-green Algae Frequently Asked Questions

http://www.dep.state.fl.us/water/bgalgae/faq.htm[10/31/2010 8:50:46 AM]

We’ve increased communication with:

Media

Local government

Elected officials

Partnering agencies

General public

The South Florida Water Management District is keeping a very close watch on blue-green algae

throughout its region: including 41 sampling sites from Lake Okeechobee; the St. Lucie River and

estuary; the Caloosahatchee River and estuary; the Kissimmee Chain of Lakes; Lake Istokpoga; and

District canals.

The St. John’s River Water Management District regularly monitors algal growth in the St. John’s River

and routinely collects water and algae samples, particularly during periods when conditions are right for

algal proliferation.

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Whom can I contact to report a blue-green algae bloom or to get more information about

water quality?

There are several toll-free hotlines available for people to report fish kills or illness associated with

blue-green algae.

Fish Kill Hotline (Florida Fish & Wildlife Conservation Commission) 800-636-0511

Human Illness (Florida Aquatic Toxin Hotline) 888-232-8635

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Are there web sites for more information about blue-green algae?

http://research.MyFWC.com

http://www-cyanosite.bio.purdue.edu/

http://lakewatch.ifas.ufl.edu/ToxicAlgae/ToxicAlgae.htm

http://www.cdc.gov/hab/cyanobacteria/

http://www.wright.edu/biology/department/directory/faculty/carmichael/

http://www.sfwmd.gov/portal/page/portal/PG_GRP_SFWMD_WATERSHED/Phytoplankton_Bloom_192?

project=1144&ou=440

http://research.myfwc.com/features/category_main.asp?id=1510

http://www.doh.state.fl.us/environment/community/aquatic/cyanobacteria.htm

http://sjrwmd.com/algae/index.html

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Last updated: June 07, 2010

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