Date of Award

Spring 2005

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Harold G. Marshall

Committee Member

William Resetarits

Committee Member

David Seaborn

Call Number for Print

Special Collections LD4331.B46 E434 2005


Growth and abundance of heterotrophic dinoflagellate predators are generally attributed to the availability of algal prey. Several species of dinoflagellates feed on a wide variety of food types including fish. However the actual feeding preferences of dinoflagellates have been much less studied. In the few studies that have been carried out on dinoflagellate feeding preference, none have looked at possible factors that may affect preference. I conducted three experiments on the toxic dinoflagellate Pfiesteria piscicida and the related unnamed species Cryptoperidiniopsis brodyi which, (1) calculated the feeding preferences between algal Rhodomonas prey and fish blood cells and identified factors that effect the preferences, (2) looked for an effect of prior diet conditioning on the grazing rates of both species, and (3) compared the growth rates of both species from two different feeding histories. Data from these three experiments demonstrate that P. piscicida and C. brodyi feed on both algal and fish prey and have the ability to feed preferentially. Both species of dinoflagellates showed a strong preference for fish blood cells over Rhodomonas. Furthermore, the feeding preferences were influenced by total prey abundance, but not by prior diet conditioning.


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