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Dieren en planten

Dinoflagellates   Dinophysis   Alexandrium   Harmful algae   

Mens en Milieu

  • Dut: Alexandrium
  • Lat: Alexandrium tamarense
  • Eng: Alexandrium
  • Ger: Alexandrium
  • Dan: Alexandrium
Alexandrium, Photo taken from mcc/strainlist_a.htm


Alexandrium is one of those dinoflagellates you don't want to run into. This harmful alga poisons shellfish and fish that consume the plankton and can kill or paralyze animals as well as people that eat the (shell)fish. When it blossoms in large amounts, the seawater turns red or brown, causing a so-called red tide. However, not all red tides are necessarily Alexandrium or even harmful algae.

  • Toxic

    Alexandrium is a toxic algae beacuse it produces saxitoxine under certain conditions. Saxitoxine is one of the most deadly materials in the world and therefore used in suicide capsules. It accumulates in the food chain (bio-accumulation). In 1968 and 1975, a blossom of Alexandrium caused the death of 80% and 60%, respectively, of the seabirds around the British Farne Islands. Whales died in Canada after consuming fish poisoned by saxitoxine.
    Saxitoxine causes the disease Paralytic Shellfish Poisoning (PSP) in people. It leads to paralysis and even death in extreme cases. In 1989, Alexandrium was reported for the first time in Dutch waters, however the toxic material has not yet been found in shellfish.
    Thanks to the self-cleansing power of the shellfish, the toxins can be washed out of the shellfish meat. However, European regulations have a monitoring requirement to limit the risks for consumers.