CDC

Marine Environments

Marine or saltwater harmful algal bloom (HAB) toxins can cause a variety of illnesses in humans and animals. Exposure to marine HAB toxins can occur through direct contact by swimming, breathing in aerosolized toxins (toxins in water turned into tiny airborne droplets or mist), or eating toxin-contaminated shellfish or finfish 1. Human illnesses are commonly caused by eating toxin-contaminated seafood, including shellfish and finfish 2. In marine mammals, fish, and other aquatic marine life, exposure to HAB toxins can cause widespread illness or death. Birds can also get sick by eating algae, drinking contaminated water, or eating contaminated marine fish or shellfish 3. For example, pelicans and cormorants have been poisoned by these toxins, and, in some cases, thousands of birds have died 4.

Two major groups of marine phytoplankton, diatoms and dinoflagellates, produce HAB toxins. Marine HABs have occurred in the Gulf of Mexico, the Atlantic coast, and the Pacific coast in the United States. Two major groups of marine phytoplankton, diatoms and dinoflagellates, produce HAB toxins. Some common marine HAB toxins include brevetoxins, azaspiracid, ciguatoxins, domoic acid, okadic acid, and dinophysistoxins 5.

Humans and Marine Water-associated Illnesses

Skin Contact and Inhalationexpandcollapse

Marine HABs can cause a variety of illnesses in people. Marine HABs produced by dinoflagellates that appear red in color are commonly referred to as red tides. Florida red tides, the most well-known marine HABs in the United States, occur every year in the Gulf of Mexico. Florida red tides are caused by the dinoflagellate Karenia brevis which can produce toxins called brevetoxins. People can be exposed to brevetoxins through skin contact or inhalation. Exposure to brevetoxins in humans can cause various symptoms, including the following 1-4:

  • Respiratory irritation (coughing, sneezing)
  • Shortness of breath
  • Throat irritation
  • Eye irritation
  • Skin irritation
References
  1. Kirkpatrick B, Fleming LE, Squicciarini D, Backer LC, Clark R, Abraham W, Benson J, Cheng YS, Johnson D, Pierce R. Literature review of Florida red tide: implications for human health effects. Harmful Algae. 2004;3(2):99-115.
  2. Backer LC, Kirkpatrick B, Fleming LE, Cheng YS, Pierce R, Bean JA, Clark R, Johnson D, Wanner A, Tamer R. Occupational exposure to aerosolized brevetoxins during Florida red tide events: effects on a healthy worker population. Environ Health Perspect. 2005;113(5):644-9.
  3. Fleming LE, Kirkpatrick B, Backer LC, Bean JA, Wanner A, Dalpra D, Tamer R, Zaias J, Cheng YS, Pierce R. Initial evaluation of the effects of aerosolized Florida red tide toxins (brevetoxins) in persons with asthma. Environ Health Perspect. 2005;113(5):650-7.
  4. Kirkpatrick B, Fleming LE, Backer LC, Bean JA, Tamer R, Kirkpatrick G, Kane T, Wanner A, Dalpra D, Reich A. Environmental exposures to Florida red tides: Effects on emergency room respiratory diagnoses admissions. Harmful algae. 2006;5(5):526-33.

 

Ingestion: Eating Contaminated Seafood and Marine Toxin Poisoning

Marine HAB toxins can build up in seafood when fish or shellfish eat toxin-producing algae. Humans and animals that eat these contaminated fish or shellfish can become poisoned from HAB toxins, making them sick. Most human illnesses from HABs occur when people eat contaminated seafood 2,6. Symptoms of HAB toxin poisoning can vary depending on the type of HAB toxin. Marine toxins and toxin poisoning information is listed below.

Note: For information regarding seafood advisories, please visit the Environmental Protection Agency's (EPA) Choose Fish and Shellfish Wisely web pages.

What can I do to prevent poisoning by marine HAB toxins?

General Guidelines to Avoid Marine Toxin Poisoning expandcollapse

  • Although any person eating fish or shellfish containing HAB toxins may become ill, persons with weakened immune systems or chronic liver disease could potentially have more severe illnesses.
  • HAB toxins are not destroyed by storage, such as freezing or salting, or by cooking, such as grilling or frying.
  • Check with local health officials before collecting shellfish, and look for advisories about harmful algal blooms or water conditions that may be posted at fishing supply stores, by beach managers, or local health authorities. HAB advisories are posted online by many coastal states.
  • Do not eat finfish or shellfish sold as bait. Bait products do not need to meet the same food safety regulations as seafood for human consumption.

Animals and Marine Water-associated Illnesses

Skin Contact and Ingestionexpandcollapse

Contact with marine HABs have been fatal for aquatic animals. During November-December 2007, a widespread die-off of seabirds was caused by a massive red tide produced by the dinoflagellate Akashiwo sanguinea in Monterey Bay, California 1. Affected birds that came into direct contact with the red tide were covered in a slimy material produced by the HAB which coated their feathers, affecting their natural water repellency. The birds’ feathers became soaked with water, and their body temperatures dropped dangerously low 1. There were no confirmed reports of human illness related to this HAB.

Marine HABs have also caused neurologic effects in animals including aquatic animals and birds 1,2. Over 400 sea lions, seals, and birds died or were affected by a HAB produced by the diatom Psuedonitzschia austrailis near Monterey Bay, California. The HAB produced domoic acid, a neurotoxin, which was also detected in mussels, anchovies, and sardines that were likely eaten by the sea lions 3.

References
  1. Jessup DA, Miller MA, Ryan JP, Nevins HM, Kerkering HA, Mekebri A, Crane DB, Johnson TA, Kudela RM. Mass stranding of marine birds caused by a surfactant-producing red tide. PLoS One. 2009;4(2):e4550.
  2. Work TM, Barr B, Allison MB, Fritz L, Quilliam MA, Wright JLC. Epidemiology of domoic acid poisoning in brown pelicans (Pelecanus occidentalis) and Brandt's cormorants (Phalacrocorax penicillatus) in California. J Zoo Wildl Med. 1993;24(1):54-62.
  3. Scholin CA, Gulland F, Doucette GJ, Benson S, Busman M, Chavez FP, Cordaro J, DeLong R, De Vogelaere A, Harvey J. Mortality of sea lions along the central California coast linked to a toxic diatom bloom. Nature. 2000;403(6765):80-84.

 

References
  1. Fleming L, Backer L, Rowan A. The epidemiology of human illnesses associated with harmful algal blooms. In: Massaro E, ed. Handbook of Neurotoxicology: Humana Press; 2002:363-81
  2. Lipp EK, Rose JB. The role of seafood in foodborne diseases in the United States of America. Rev Sci Tech. 1997;16(2):620-40.
  3. Stewart I, Seawright AA, Shaw GR. Cyanobacterial poisoning in livestock, wild mammals and birds–an overview. Adv Exp Med Biol. 2008;619:613-37.
  4. Work TM, Barr B, Allison MB, Fritz L, Quilliam MA, Wright JLC. Epidemiology of domoic acid poisoning in brown pelicans (Pelecanus occidentalis) and Brandt's cormorants (Phalacrocorax penicillatus) in California. J Zoo Wildl Med. 1993;24(1):54-62.
  5. Van Dolah FM, Doucette GJ, Gulland FM, Rowles TL, Bossart GD. 10 Impacts of algal toxins on marine mammals. In eds. Toxicology of Marine Mammals. 2003:247.
  6. Masó M, Garcés E. Harmful microalgae blooms (HAB); problematic and conditions that induce them. Mar Pollut Bull. 2006;53(10–12):620-30.

Healthy Water Sites

Get Email Updates

To receive email updates about this page, enter your email address:

What's this?Submit
Top