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What's up with Harmful Algal Blooms and Domoic Acid Poisoning?

Harmful Algal Blooms (HABs)
Image of diatom that produces domoic acid
  1. What are harmful algal blooms (HABs)?
  2. What is the nature of the current harmful algal bloom (HAB) within the MBNMS?
  3. Can I find out the size and location of the current harmful algal bloom within the MBNMS?
  4. How does a harmful algal bloom expose animals and humans to natural marine toxins, such as domoic acid?
  5. Is the current harmful algal bloom within the MBNMS a threat to human health?
  6. Who monitors for human health hazards from harmful algal blooms? Where can I get information about health advisories and seafood quarantines?
  7. Can I get sick simply by coming into contact with ocean waters containing elevated levels of domoic acid?
  8. What are symptoms of domoic acid poisoning?
  9. Can domestic pets be affected by contact with ocean waters containing elevated levels of domoic acid?

Answers

  1. What are harmful algal blooms (HABs)?
    Harmful algal blooms are caused by high concentrations of certain free-floating single-celled plants in the ocean (known as phytoplankton) that produce toxins that spread into the marine ecosystem. Of approximately 5,000 known species of phytoplankton (microalgae), only a few dozen are known to produce toxic chemicals that can harm fish, shellfish, marine mammals, seabirds, and humans. For more information, see http://www.cencoos.org/learn/blooms.
  2. What is the nature of the current harmful algal bloom (HAB) within the MBNMS?
    The current HAB in the Monterey Bay area involves a species of phytoplankton known as Pseudo-nitzschia that produces a toxin known as domoic acid through the process of photosynthesis. The current algal bloom is the largest of its kind to occur in the Monterey Bay area within the past decade. Pseudo-nitzschia and other phytoplankton are consumed by small organisms in the ocean that are, in turn, consumed by larger organisms. Top-level predators can thus accumulate high concentrations of domoic acid in their bodies. This bioaccumulation of domoic acid can cause toxic effects, leading to sickness and even death from amnesiac shellfish poisoning (ASP). For more information about the current hazardous algal bloom in central California, see http://sanctuarysimon.org/news/2015/05/massive-domoic-acid-event-in-monterey-bay/.

    Domoic acid (DA) was first associated with phytoplankton as a source of the toxin in 1987, when over 100 people were sickened and three died following consumption of DA-contaminated mussels from eastern Prince Edward Island, Canada. In California, DA was first recognized in September 1991 in Monterey Bay, when the deaths of more than 100 brown pelicans and cormorants were linked to DA poisoning. Since then, the toxin has been implicated in other deaths of marine mammals and seabirds between Monterey Bay and San Diego.

    At least nine species within the marine diatom genus Pseudo-nitzschia are now known to produce DA. In California, Pseudo-nitzschia australis and Pseudo-nitzschia multiseries are the main toxin producers.
  3. Can I find out the size and location of the current harmful algal bloom within the MBNMS?
    The Central and Northern California Ocean Observing System (CeNCOOS) is a NOAA-supported ocean observation system that analyzes data from instrument buoys, radar, and other sources to help forecast various ocean events, including hazardous algal blooms. CeNCOOS has developed an experimental hazardous algal bloom model that projects a map image of HAB distribution and density in central California ocean waters. For more information, see http://www.cencoos.org/data/models/habs.
  4. How does a harmful algal bloom expose animals and humans to natural marine toxins, such as domoic acid?
    Toxins are transferred and concentrated through the ocean food web through successive levels of predation - plankton eaten by little fish eaten by larger fish eaten by marine mammals and birds. For more information, see http://www.cencoos.org/learn/blooms/habs/impacts.
  5. Is the current harmful algal bloom within the MBNMS a threat to human health?
    Yes. According to the California Department of Public Health (CDPH), the public should take precautions to avoid certain recreationally harvested local seafood that may contain high concentrations of domoic acid. For more information about domoic acid poisoning, see this report (174K PDF). For information about health advisories and seafood quarantines, see http://www.cdph.ca.gov/healthinfo/environhealth/water/Pages/Shellfish.aspx.
  6. Who monitors for human health hazards from harmful algal blooms? Where can I get information about health advisories and seafood quarantines?
    The California Department of Public Health (CDPH) and County Health Departments are the lead agencies in determining the potential human health risks posed by local harmful algal blooms (HABs). Typically, the primary health risk stems from eating tainted seafood. For more information about domoic acid poisoning, see this report (174K PDF). For information about health advisories and seafood quarantines, see http://www.cdph.ca.gov/healthinfo/environhealth/water/Pages/Shellfish.aspx. To receive updated information about shellfish poisoning and quarantines, you can also call CDPH’s toll-free “Shellfish Information Line” at (800) 553-4133.
  7. Can I get sick simply by coming into contact with ocean waters containing elevated levels of domoic acid?
    Simple contact with ocean water containing elevated levels of domoic acid is not known to cause negative health effects to humans. Since domoic acid poisoning is caused by bioaccumulation of high concentrations of domoic acid inside the body through consumption of tainted seafood, inadvertent direct ingestion of very small amounts of seawater containing domoic acid are not likely to impact health.
  8. What are symptoms of domoic acid poisoning?
    According to a July 3 advisory from the California Department of Public Health (CDPH), Symptoms of domoic acid poisoning can occur within 30 minutes to 24 hours after eating toxic seafood. In mild cases, symptoms may include vomiting, diarrhea, abdominal cramps, headache and dizziness. These symptoms disappear within several days. In severe cases, the victim may experience trouble breathing, confusion, disorientation, cardiovascular instability, seizures, excessive bronchial secretions, permanent loss of short-term memory (a condition known as Amnesic Shellfish Poisoning), coma or death. There have been no reported illnesses associated with this current event. To see the complete CDPH advisory, go to http://www.cdph.ca.gov/Pages/NR15-047.aspx. For additional information, see this report (174K PDF).
  9. Can domestic pets be affected by contact with ocean waters containing elevated levels of domoic acid?
    Domoic acid poisoning in wild marine animals is generally associated with the consumption of ocean organisms in which toxins have bioaccumulated through successive predation across the food web. The California Department of Public Health (CDPH) and County Health Departments only assess impacts to human health from harmful algal blooms and do not provide advice regarding domestic animals. If you are concerned about potential impacts to pets from harmful algal blooms or domoic acid specifically, you should consult a veterinarian.
URL: http://montereybay.noaa.gov/includes-interface/footertop.html    Reviewed: November 17, 2017
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