Regional and global analyses of bacterial abundance relations in Missouri reservoirs

Mean abundance of heterotrophic bacteria (cells/mL) in the surface layer of Missouri reservoirs was strongly correlated with concentrations of plant nutrients, chlorophyll, and suspended solids (r > 0.78 to 0.91, n = 78). Relations of bacterial abundance to both chlorophyll and phosphorus in Missouri did not differ from the overall pattern in the published literature. Bacterial abundance was more strongly correlated with the organic fraction of the suspended solids (volatile suspended solids) than with phytoplankton biomass (chlorophyll), indicating that broad measures of organic substrate should be considered in the future. Missouri bacterial abundance and phosphorus data were combined with aggregated literature data in a meta-analysis. The resulting model was used to develop trophic state boundaries based on bacterial abundance where less than 3 million cells/mL indicates oligotrophic conditions, between 2.8 and 5.7 million cells/mL mesotrophic and greater than 5.7 million cells/mL indicates eutrophic conditions.