Frequently Asked Questions
What are the dangers of Harmful Algal Blooms?
- They spoil water quality when present in large numbers by producing odors or thick scums.
- They can make drinking water smell and taste bad.
- They can make recreational areas unpleasant.
- Dense blooms can block sunlight killing other plants and animals.
- When algae decompose they may use up oxygen in the water and cause fish kills.
- Some cyanobacteria can produce toxins that are among the most powerful natural poisons know. These toxins have no know antidotes. The toxins are poisonous to humans and may be deadly to livestock and pets.
- CyanoHABs can make people, their pets, and other animals sick. Often, the first sign that a HAB exists is a sick dog that has been swimming in a algae-filled pond. Children are at higher risk than adults for illness from CyanoHABs because they weigh less and can get a relatively larger dose of toxins.
Are all blue-green algae poisonous? - No. There are many species of blue-green algae. Some are not known to have any toxins, others have one or more different types of toxin. Species known to be toxic may only be toxic at certain times and places within the bloom. Blue-green algae are a natural part of all waterways. Under certain conditions some blue-green algae multiply to bloom levels and may produce toxins which are dangerous to livestock and humans.
What species of cyanobacteria form harmful algal blooms in fresh water? - The most common HABs in the Great Lakes region are:
- Microcystis aeruginosa
- Anabaena circinalis
- Anabaena flos-aquae
- Aphanizomenon flos-aquae
- Cylindrospermopsis raciborskii
What types of illnesses can people and animals get from exposure to HABS?
- Getting it on the skin may give people a rash, hives, or skin blisters (especially on the lips and under swimsuits).
- Inhaling water droplets from irrigation or water-related recreational activities can cause runny eyes and nose, a sore throat, asthma-like symptoms, or allergic reactions.
- Swallowing water that has toxins in it can cause:
- Acute, severe gastroenteritis (including diarrhea and vomiting).
- Liver toxicity (i.e., increased serum levels of liver enzymes). Symptoms of liver poisoning may take hours or days to show up in people or animals. Symptoms include abdominal pain, diarrhea and vomiting.
- Neurotoxicity. These symptoms can appear within minutes after exposure. In dogs, the neurotoxins can cause salivation and other neurological symptoms, including weakness, staggering, difficulty breathing, convulsions, and death. People may have numb lips, tingling fingers and toes, or they may feel dizzy.
- Paralytic shellfish poisoning (PSP). PSP is caused by consumption of shellfish (e.g., mussels and clams) which bioaccumulate a toxin produced by dinoflagellates (red tide). Dinoflagellates similar to those responsible for PSP are occasionally found in the Great Lakes, but dangerous levels of PSP toxin have not been observed there.
How could you be exposed to HABs and toxins?
- Drinking water that comes from a lake or reservoir with a HAB.
- Drinking untreated water.
- Engaging in recreational activities in waters with HABs.
- Inhaling aerosols from water-related activities such as jet skiing or boating.
- Inhaling aerosols when watering lawns, irrigating golf courses, etc., with pond water.
- Using cyanobacteria-based dietary supplements that are contaminated with microcystins.
- Consuming contaminated fish or shellfish (see safety precautions below).