Algae from Clearwater Lake, SE Missouri:  A Euglena Bloom in August 2010

This website has been produced by Russell G. Rhodes, Department of Biology, Missouri State University solely for educational purposes (August 20, 2010)

A reddish area of water on Clearwater Lake in SE Missouri was of concern to many persons.  One of the reasons is that reddish blooms of algae can sometimes be toxic to fish and other aquatic animals.  Also, the appearance is unsightly and makes boats and fishing gear soiled.   Samples of the water were collected by personnel of the Missouri Department of Conservation and preserved in formalin.  The samples were later analyzed microscopically. 

The organism causing the bloom was a species of Euglena.  Images are included below:

Table 1.  Euglena bloom in Clearwater Lake, SE Missouri, August 2010

Appearance of reddish water on Clearwater Lake, August 2010 Appearance of reddish water on Clearwater Lake, August 2010 Oily appearance of large clumps of reddish water Set of sample bottles that show the reddish color of the water
Euglena in the sample, 100x, preserved in formalin Euglena showing characteristic anterior flagellum 400X Green "normal" colored Euglena, 400x Red and green Euglena, 400x preserved in formalin

The reddish water was caused by a pigment, haematochrome, that had accumulated in the cells of Euglena.  This phenomenon was a response to extensive periods of sun and calm water.  The production of the red pigment was probably the response to intense sunlight and aided in protecting the chlorophyll, the green pigment in the cells of Euglena from degradation.

Of interest was a condition in an aquaculture pond in North Caroline in which a bloom of Euglena caused an extensive fish kill.  From this incident and others a toxin was isolated and shown to have toxic properties.  Euglenophycin  

Any use of images must have permission of Russell G. Rhodes