Bacterivory in Pelagic Marine Ecosystems

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Landry 9315432 Most of the organic production in the oligotrophic open oceans is created by or passed through bacterioplankton and consequently made available for consumption by small flagellated protozoa which feed by direct interception. At spatial scales relevant to such organisms, predator-prey interactions are likely to be controlled by the balance of molecular and hydrodynamic forces acting or small particles moving relative to one another in a liquid media, rather than by complex hunting or avoidance behaviors. Thus, it may be possible to understand clearance rates and selectives of bacterivorous flagellates from physical and chemical first principles. The present research focuses on the influences of bacterial motility and physiochemical surface properties (hydrophobicity and electrostatic charge) on zooflagellate bacterivory. In an ecological context, increased motility and hydrophobicity may provide survival advantages to bacterioplankton in oligotrophic environments. However, such characteristics would also increase the frequency of random contacts with predators and would be a likely disadvantage in terms of mortality rate. Dr. Landry will use an integrated descriptive, experimental, and theoretical approach to: 1) characterize size, abundance, motility, and surface properties of natural microbial communities in waters of Hawaii; 2) test the effects of prey motility and surface properties on feeding rates of zoofagellates; 3) determine the selective advantages of motility and hydrophobicity as a function of nutritional environment and zooflagellate predation; and 4) continue development of a Force-Balance model of direct contact feeding. ***