Algal blooms in lakes, ponds and canals can produce toxins harmful to people and animals.
Eating fish or shellfish that carry algal toxins can cause foodborne illnesses.
You can get sick from exposure to algal blooms during recreational water activities.
Jump to: Protect Your Health | Identifying Algal Blooms | Report an Algal Bloom | Resources
Illnesses Caused by Algal Blooms and Toxins
You can get sick from eating ocean fish or shellfish if it contains algal toxins.
| Type of food poisoning | Associated algae or toxin | Common carriers |
|---|---|---|
Ciguatera fish poisoning | Gambierdiscus toxicus, a naturally occurring microscopic marine algae | Snapper, jacks, sea bass, grouper, triggerfish and barracuda |
| Shellfish poisoning | Saxitoxins | Shellfish, including but not limited to: Clams, mussels, oysters |
Symptoms of fish and shellfish poisoning
Symptoms vary based on the toxin(s) present, how much toxin is present and how much fish or shellfish you've eaten. They may include:
- Nausea
- Vomiting
- Neurologic symptoms, such as tingling fingers or toes
- Temperature reversal sensation (cold things feel hot and hot things feel cold).
You can get treated for symptoms. Symptoms usually go away in days or weeks but can last for years.
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Swimming, playing and wading in toxic algal blooms can expose you to cyanotoxins. Cyanotoxin exposure can make you sick.
| Cyanotoxins Common in N.C. | Symptoms | How Exposure Occurs |
|---|---|---|
| Microcystin | Headache, sore throat, vomiting and nausea, stomach pain, dry cough, diarrhea, blistering around the mouth, and pneumonia | |
| Cylindrospermopsin | Fever, headache, vomiting, bloody diarrhea |
North Carolina has no documented reports of algal blooms causing sickness. There are steps you can take to avoid algal bloom exposure.
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Protect Yourself and Your Family
Children are especially vulnerable to algal toxins. If ingested, toxins can cause more adverse health effects in children due to their size.
Algal toxins can be lethal to pets, livestock and wildlife.
Prevent exposure to algal blooms
- Keep children and pets away from waters that appear discolored or scummy.
- Do not handle or touch large accumulations of algae, also called “scums” or “mats.”
- Do not water ski or jet ski over algal mats.
- Do not use scummy water for cleaning or irrigation.
- If you come into contact with an algal bloom, wash thoroughly.
- If you are unsure whether a bloom is present, it is best to stay out of the water.
Seek immediate care if...
- Your child appears ill after being in waters with a bloom.
- Your pet stumbles, staggers or collapses after being in a pond, lake or river.
How do I identify an algal bloom?
Algal blooms grow in fresh bodies of water with low flow, like lakes, ponds and canals.
Blooms are caused by a rapid increase of algae. They are most likely to occur in hot, dry weather, or when a body of water has increased nutrients.
Signs of algal blooms in water
Cyanobacteria, or blue-green algae, is a common freshwater algae in North Carolina. Here are signs that cyanobacteria is present in water:
- Water is neon green, blue-green or reddish-brown in color
- Bad smell or taste
- Foam or scum on water's surface
You can't tell whether a bloom is harmful by looking at it. Avoid water suspected of having an algal bloom. When in doubt, stay out!
How can I report algal blooms?
The N.C. Department of Environmental Quality (NCDEQ) monitors and investigates reports of algal blooms across the state. NCDEQ can collect algal bloom samples to analyze for algae that may pose a health risk.
Report an algal bloom online or contact your regional NCDEQ office.
Check pending and completed reports: NCDEQ Algal Bloom Report Dashboard.
More info on algal blooms from other state and national agencies: