Blue-Green Algae Brief by Lindsay Boyce MPH Candidate
Cyanobacteria also known commonly as Blue-Green Algae grow in any type of water and uses sunlight to create food to support life. This bacterium is usually too small to be seen but can create colonies called algae blooms that are visible to the naked eye.
Some cyanobacteria can create harmful blooms know as CyanHABs. These blooms are harmful to both humans and animals. They are dangerous for many reasons including, dense blooms can block sunlight and oxygen from the water killing off the plant and animal life that are living in the particular water source. Also, some cyanHABs can produce natural toxins; these toxins can make animals and humans sick. The first sign the HAB exists is a sick dog or other pet that has been swimming in an algae laden watering hole. Children are at a greater risk than adults due to the fact that they are smaller in size and can get a large dose of toxin if exposed.
Exposure to these toxins comes in many forms; drinking water that comes from a lake or other water source with CyanHABs. Using recreational waters that are contaminated with CyanHABs and also aerosols inhaled from water the lawn.
The symptoms and or illnesses associated with this type of toxin are rash, nausea and or vomiting other gastrointestinal disorders, liver toxicity, and neurotoxicity.
Prevention is important to limiting exposure. Not swimming or participating in other recreational activities involving water where cyanobacteria exist. Do not let pets swim in areas where water is discolored or where you can visibly see algae. Also, it is important to report any musty smelling or bad tasting water to a utility company.
A reduction of the use of pesticides and fertilizers will help in eliminating the progression of blue green algae. Also, proper maintenance of the septic system and using natural vegetation to buffer incoming water into ponds and lakes are important ways in the prevention of Blue-Green Algae.
Toxicity of Blue-Green Algae
by Katherine Fite
Blue-green algae, also known as cyanobacteria, are a group of photosynthetic organisms. There are dozens of species that thrive on land and in fresh and marine water environments. Blue-green algae are usually found in ponds, lakes and other slow-moving waters. Algal blooms occur under certain conditions. In warmer weather, with high levels of nutrients such as nitrogen and phosphorous, algal blooms flourish. While most algae blooms in the summer months, some species are known to grow in colder conditions.
There are dozens of species of algae that produce toxins. The toxins produced by cyanobacteria are called cyanotoxins. There are several types of cyanotoxins: hepatoxins are toxins that harm the liver, cytotoxins attack cells, dermatoxins that irritate the skin, and neurotoxins attack the nervous system.
Microcystis, a species of cyanobacteria, produces the hepatoxin microcystin. Microsytin is most common cyanotoxin found in water and is responsible for most poisonings in organisms from algal blooms. . The Microsystis species can live in many different water conditions, including water with extremely varying temperatures and pH. The toxin is released into the water when the cells die or burst. Once the toxin-infested water is ingested, microcystin inhibits liver enzymes from maintaining structural support in the liver. This toxin mostly affects livestock and other wildlife that drink from water sources that have algal blooms. People can also be exposured to microcystin by either accidently swallowing lake/pond water with algal blooms or consuming contaminated produce from gardens that used lake water for gardening.
Anabeana is another species of blue green algae that produces two types of neurotoxins: anatoxin and saxitoxin. Anatoxin is an extremely potent toxic substance the cause death within minutes of exposure. It irreversibly binds to the acetylcholine receptor. The sodium channels of the cell are locked open, become over-stimulated and causes respiratory paralysis and death. Saxitoxin is similar to Anatoxin. It also interferes with sodium channels but blocks them, causing under-stimulation and slow respiratory paralysis. Both of these toxins are known to cause death in wildlife and livestock that drink infected water. There have also been cases of people experiencing numbness of the mouth and tongue after consuming mollusks or fish that contain small doses of the toxins.
Even though algae blooms do release toxins, not all blooms are harmful. A little less than 50% of blooms are harmless to human and wildlife health.