Selph, K. University of Hawaii, kselph@soest.hawaii.edu
Landry, M. University of Hawaii, landry@soest.hawaii.edu

 
ENHANCED BACTERIAL GROWTH IN THE PRESENCE OF MARINE NANOFLAGELLATES GROWN IN CONTINUOUS CULTURE
 
Growth, grazing, and digestion rates of a marine heterotrophic nanoflagellate, Paraphysomonas bandaiensis, were studied using two-stage nitrogen-limited chemostats. Chemostats allowed the study of the predator and prey in exponential growth state for a prolonged period. The chemostats operated at a dilution rate of 0.5 d^-1, with heterotrophic bacteria in the first stage leading to bacteria and flagellates in the second stage. Samples were withdrawn daily for flow cytometry-based estimates of bacterial and flagellate abundances, and flagellate biovolumes were determined on live aliquots using an Elzone particle counter. Grazing experiments, using tracer concentrations of fluorescently labeled bacteria and beads, yielded an average clearance rate of 2.1 nl flagellate^-1 h^-1. Bacterial population growth rates, estimated from the removal rates of the nanoflagellate predators, were significantly enhanced, by a factor of 20 on average, over bacterial growth rates in the first stage chemostat or the second stage of a control chemostat, which contained no flagellates. Mass balance calculations demonstrated that the enhancements in bacterial growth rates could be supported by nitrogen regeneration by the flagellate.
 
Day: Wednesday, Feb. 3
Time: 12:15 - 12:30pm
Location: Hilton of Santa Fe
 
Code: SS21WE0200H