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Publication Date


Document Type

Honors Project


Biological Sciences


Planktonic ciliates play an important role in the food webs of the Earth's oceans as these organisms provide a critical link between bacteria and larger zooplankton, and are important grazers on harmful algal bloom species. However, little is known about the distribution of ciliates and other eukaryotic microbes in marine plankton and sediments. The increased use of molecular technologies in studying the diversity of microorganisms has challenged Martinu Willem Beijerinck's famous metaphor "in microorganisms, everything is everywhere, the environment selects" and has shown that ciliate diversity is much larger than anticipated. Molecular approaches have also revealed levels of diversity not captured by traditional morphological methods. Using a culture independent approach we sampled the diversity of ciliates within Choreotrichia and Oligotrichia, the two subclasses that dominate ciliate communities in near coastal waters. Our findings are consistent with those from similar studies of microbial diversity in natural environments. While we have not yet reached sampling saturation at all of our sites, the levels of diversity were similar across sites, with the highest diversity values in the sediment. At each stake there was a different assemblage of haplotypes and within each of our samples we found a few dominating cosmopolitan haplotypes, a few other common and ubiquitous haplotypes, and a large variety of rare sequences some of which had not been characterized before. The patterns and trends of haplotype distribution highlighted in this study suggest methods that will aid future hypothesis testing in the study of microbial diversity.




45 p. : ill. (some col.), col. map Honors project-Smith College, Northampton, Mass., 2009. Includes bibliographical references (p. 30-32)