Freshwater Environments

People or animals can be directly exposed to cyanotoxins in freshwater during recreational activities or by breathing in aerosolized toxins (toxins in water turned into tiny airborne droplets or mist). People or animals exposed to cyanotoxins through direct skin contact or inhalation may experience the following symptoms ^{1, 2}:

• Skin irritation
• Eye irritation
• Nose irritation
• Throat irritation
• Respiratory illness

References

1. Carmichael WW. Health effects of toxin-producing cyanobacteria: "The CyanoHABs". Hum Ecol Risk Assess. 2001;7(5):1393-407.
2. Hilborn ED, Roberts VA, Backer L, DeConno E, Egan JS, Hyde JB, Nicholas DC, Wiegert EJ, Billing LM, DiOrio M. Algal bloom-associated disease outbreaks among users of freshwater lakes—United States, 2009–2010. MMWR Morb Mortal Wkly Rep. 2014;63(1):11-5.

People can be exposed to cyanotoxins by eating freshwater fish from cyanotoxin-contaminated lakes or ponds or by drinking cyanotoxin-contaminated water. Additionally, some toxins may be ingested when taking blue-green algae dietary supplements ^1,2. People who ingest cyanotoxins may experience the following symptoms ³:

• Abdominal pain
• Headache
• Neurological symptoms
• Vomiting
• Diarrhea
• Liver damage
• Kidney damage

References

1. Gilroy DJ, Kauffman KW, Hall RA, Huang X, Chu FS. Assessing potential health risks from microcystin toxins in blue-green algae dietary supplements. Environ Health Perspect. 2000;108(5):435-9.
2. Heussner AH, Mazija L, Fastner J, Dietrich DR. Toxin content and cytotoxicity of algal dietary supplements. Toxicol Appl Pharmacol. 2012;265(2):263-71.
3. Bienfang P, DeFelice S, Laws E, Brand L, Bidigare R, Christensen S, Trapido-Rosenthal H, Hemscheidt T, McGillicuddy D, Anderson D. Prominent human health impacts from several marine microbes: history, ecology, and public health implications. Int J Microbiol. 2010;2011.

Pets, livestock, and wildlife can be poisoned through direct contact by swimming in waters with a HAB or by drinking cyantoxin-contaminated water. Coyote deaths have been reported after they were believed to have eaten fish that washed up on the beach from a part of the Gulf of Mexico that was experiencing a HAB ^1-3. Dogs are especially at risk to cyanotoxin poisoning due to their behaviors, which include swimming in contaminated waters, drinking the water, and licking algae or scum from their fur after swimming ². Domestic pets may also be poisoned by blue-green algae dietary supplements that are contaminated with cyanotoxins ³.

A HAB may also make birds sick. Side effects of cyanotoxin poisoning in birds are sometimes confused with, or occur at the same time with, avian botulism, a disease that paralyzes birds. Birds can get avian botulism when they eat toxins produced by the bacteria Clostridium botulinum directly or eat insects containing the toxins ⁴. Avian botulism is becoming more common in the Great Lakes region since it was first reported in 1963, and there is some evidence that Clostridium botulinum can grow in the presence of algae commonly found in the Great Lakes region ⁴.
Animals who are exposed to cyanotoxins may experience the following symptoms ^{2, 5-7}:

• Excessive salivation
• Vomiting
• Fatigue
• Staggered walking
• Difficulty breathing
• Convulsions
• Liver Failure
• Death

Death in animals can occur within hours to days of exposure ².

References

1. Castle KT, Flewelling LJ, Bryan J, Kramer A, Lindsay J, Nevada C, Stablein W, Wong D, Landsberg JH. Coyote (Canis latrans) and domestic dog (Canis familiaris) mortality and morbidity due to a Karenia brevis red tide in the gulf of Mexico. J Wildl Dis. 2013;49(4):955-64.
2. Backer LC, Landsberg JH, Miller M, Keel K, Taylor TK. Canine cyanotoxin poisonings in the United States (1920s–2012): Review of suspected and confirmed cases from three data sources. Toxins. 2013;5(9):1597-628.
3. Bautista AC, Moore CE, Lin Y, Cline MG, Benitah N, Puschner B. Hepatopathy following consumption of a commercially available blue-green algae dietary supplement in a dog. BMC Vet Res. 2015;11(1):136.
4. Chun CL, Ochsner U, Byappanahalli MN, Whitman RL, Tepp WH, Lin G, Johnson EA, Peller J, Sadowsky MJ. Association of toxin-producing Clostridium botulinum with the macroalga Cladophora in the Great Lakes. Environ Sci technol. 2013;47(6):2587-94.
5. Stewart I, Seawright AA, Shaw GR. Cyanobacterial poisoning in livestock, wild mammals and birds–an overview. Adv Exp Med Biol. 2008;619:613-37.
6. Briand J-F, Jacquet S, Bernard C, Humbert J-F. Health hazards for terrestrial vertebrates from toxic cyanobacteria in surface water ecosystems. Vet Res. 2003;34(4):361-77.
7. Ferrão-Filho AdS, Kozlowsky-Suzuki B. Cyanotoxins: bioaccumulation and effects on aquatic animals. Mar Drugs. 2011;9(12):2729-72.

When a HAB decomposes, it can use up the oxygen in a body of water and kill fish. Fish and other aquatic animals (vertebrates or invertebrates that live in the water) may also eat cyanobacteria and store cyanotoxins in their bodies. When other animals eat these animals, the toxins can build up and move up the food chain through a process called bioaccumulation ¹. Some cyanotoxins can also kill fish by affecting their gills and preventing fish from breathing ².

References

1. Ferrão-Filho AdS, Kozlowsky-Suzuki B. Cyanotoxins: bioaccumulation and effects on aquatic animals. Mar Drugs. 2011;9(12):2729-72.
2. Zimba P, Khoo L, Gaunt P, Brittain S, Carmichael W. Confirmation of catfish, Ictalurus punctatus (Rafinesque), mortality from Microcystis toxins. J Fish Dis. 2001;24(1):41-47.