Sheela (Bavikatty) Mahnke, Duke University

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Since the discovery and subsequent acceptance of the microbial loop. Scientists have been working to understand its role in the movement of carbon within the marine ecosystem. The following study is a further attempt to define the relationships of the microbial loop by testing for the ingestion of fluorescently labeled bacteria (FLB's) by the mixotrophic dinoflagellate Gymodineum sanguineum. Feeding experiments were run to test for grazing rates; the G. sanguineum did not ingest the FLB's. Next, feeding experiments were done using the ciliate Uronema marinum, the flagellate Paraphysomonas sp., and natural samples. The FLB's were ingested by the ciliate. In summary, FLB's were not ingested by Gymnodineum sanguineum, however, they were edible as proven by their ingestion by the ciliates.