Alexandrium (dinoflagellate)

Alexandrium is a genus of dinoflagellates, which are single-celled algae that are often responsible for harmful algal blooms. Some species in this genus produce toxins that can cause paralytic shellfish poisoning in humans.

Description

The cells of Alexandrium are typically round or oval and have two flagella for movement. They have a complex life cycle that includes both sexual and asexual reproduction. The cells can form cysts, which are resistant to harsh environmental conditions and can remain dormant in the sediment for years.

Distribution

Alexandrium species are found in oceans worldwide, but they are most common in temperate and subarctic waters. They are often found in coastal areas, where they can form dense blooms under certain conditions.

Harmful algal blooms

Some species of Alexandrium, such as Alexandrium tamarense, Alexandrium catenella, and Alexandrium fundyense, produce toxins that can cause paralytic shellfish poisoning. These toxins can accumulate in shellfish that feed on the algae, and humans who consume the contaminated shellfish can become ill. Symptoms of paralytic shellfish poisoning include numbness, tingling, dizziness, nausea, and in severe cases, respiratory failure.

Prevention and control

Monitoring programs are in place in many areas to detect the presence of Alexandrium and other harmful algal bloom species. When high levels of these algae are detected, shellfish harvesting may be temporarily closed to prevent human exposure to the toxins. Research is ongoing to develop methods for predicting and controlling harmful algal blooms.

See also

• Dinoflagellate
• Harmful algal bloom
• Paralytic shellfish poisoning

References

Alexandrium (dinoflagellate) Resources
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