The genus Pseudo-nitzschia includes several species of diatoms known to produce the neurotoxin known as domoic acid, a toxin that is responsible for the human illness called amnesic shellfish poisoning (ASP). This genus of phytoplankton is known to form harmful algal blooms in coastal waters of Canada, California, Oregon, Washington, Europe, Asia, New Zealand, Central and South America.
These samples of Pseudo-nitzschia were collected at Fort Worden in Port Townsend, Washington, USA by 
Ashleigh Pilkerton and Lilianna Wolf for the 
Port Townsend Marine Science Center (2015 Citizen Science Program).
The images below were captured using the 
DCM3.1 microscope camera (3.2 megapixels) and a Zeiss 
Phase Contrast microscope.
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| Pseudo-nitzschia under the microscope. | 
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| Pseudo-nitzschia under the microscope. | 
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| Pseudo-nitzschia under the microscope. | 
A huge thank you to the 
Port Townsend Marine Science Center Citizen Science Program 2015 for sharing these images with 
Microscope World. 
You can learn more about Pseudo-nitzschia 
here.