ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

"Red Tide" and shellfish poisoning

Updated on July 12, 2011

If you love to eat hard or soft-shell clams,oysters, mussels, scallops, whelks, and moon snails, you should read this.

Recently, researchers from the Gulf of Maine Toxicity project (funded by NOAA) have observed a larger than usual "seed bed" lying off the coast of New England. Researchers fear that this finding is a signal for a major algae bloom during the spring and summer of 2010, caused by the toxic phytoplankton (a microscopic plant-like organism that lives in the ocean) called Alexandriumfundyense. This organism is responsible for harmful algal blooms which are called “Red Tide” and the resulting poisoning of shellfish.

Red Tide emerges from a "population explosion" of toxic, naturally occurring microscopic plankton (in this case, the Alexandrium Fundyense).These "Blooms" are coastal phenomena caused by environmental conditions which includes: sea low salinity, high nutrient content, warm surface temperatures and calm seas. Also, rain followed by sunny weather in the summer months is often associated with this natural event.

The term "Red Tide" is used to name this phenomenon because water in coastal areas can be colored red by the algae. Although toxic blooms often turn the water reddish brown, many nontoxic species or reddish brown plankton cause the same discoloration. But it is also possible that toxic plankton may be numerous enough to toxify shellfish, but not sufficiently abundant to discolor water. Discolored water should always be regarded with suspicion, but even during a red tide event caused by Alexandrium fundyense, there is no risk with regard to swimming in the water.

Why should I care?

Although these algae pose not direct treat to humans, shellfish are particularly prone to contamination because the toxins they produce can be accumulated as mollusks feed by filtering microscopic food out of the water. During "Red Tides" shellfish harvested from affected areas are not safe to eat. But shrimp, crabs, Lobster meat and most finfish, do not normally accumulate toxin and are safe to eat from affected waters. On the other hand, Lobster tomalley (the green part or liver) is not safe to eat in general, and particularly during red tide events because this part of the lobster can buildup high levels of toxins and other pollutants.

Since toxic shellfish will taste and appear no different than nontoxic shellfish, precautions must be taken in order to avoid consumption of contaminated mollusks. The only way to determine if shellfish contain unsafe levels of toxin is testing. In the United States, all shellfish-producing states have monitoring programs that test water, sediments, and shellfish for contamination.

Is important to know that cooking does not destroy the red tide toxin.

Recommended books about Red Tides and Food Poisoning

What happens if someone consumes shellfish from a Red Tide area?

Human and animal consumption of contaminated shellfish may generate severe poisoning effects because the Alexandrium fundyense, produces one of the most potent toxins known to scientists: saxitoxin. This toxin acts on the voltage-gated sodium channels of nerve cells, preventing normal cellular function and leading to paralysis. Therefore, eating toxic shellfish can cause a condition called Paralytic Shellfish Poisoning (PSP). This condition immediately affects the gastrointestinal and nervous system, with symptoms usually occurring within 30 minutes. Severity depends on the amount of toxin consumed.

Mild Symptoms include:

  • headache
  • dizziness
  • nausea
  • vomiting
  • rapid pain
  • anuria (non-passage of urine)

Moderate to Severe symptoms include:

  • tingling on the face and neck progressing to numbness
  • numbness and incoordination of the extremities
  • respiratory difficulty
  • difficulty swallowing
  • sense of throat constriction
  • speech incoherence or complete loss of speech
  • brain stem dysfunction
  • complete paralysis

What to do if someone present symptoms of PSP?

  1. Seek proper medical attention immediately.
  2. If medical attention cannot be reached contact the nearest poison control center.

For a First Aid for Victims of Paralytic Shellfish Poisoning guide, follow this link.

If you want to learn more about marine toxins and the diseases they may cause, visit the U.S. Center for Disease Control and Prevention.


    0 of 8192 characters used
    Post Comment

    • profile image


      8 years ago

      it was very usefull information about oyster poisoning because of ingestion of poisoned oyster which i did and i suffered from it having nausea vomiting headache abdominal pain after 3 hours i acte 85 mg can of oister


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)