Microbial Predator-Prey Interactions Within the Estuarine Microbial Loop
Marine dissolved organic matter (DOM) is one of the largest active reservoirs of reduced carbon at the earth’s surface and, to a large extent, as the primary consumers of this DOM, bacterial heterotrophs control its fate via assimilation and remineralization processes. DOM that is assimilated into bacterial biomass is potentially available for trophic transfer via the microbial loop (see figure) and as such must be accounted for in estimates of marine carbon flux. The overall goal of the work presented here was to evaluate how transient changes in both bottom up factors (supply of bulk DOM, i.e. both DOC and DON) and sideways factors transiently influence bacterial community composition and associated functional changes within the predacious guilds using novel approaches such as modified stable isotope probing (SIP) approach (see figure below). An improved understanding of these tightly coupled microbial predator-prey interactions and the effects of DOM supply will lead to a better understanding of carbon cycling processes within the microbial loop in coastal systems.
We studied bacterial community over a tidal cycle in an attempt to identify triggers behind community succession. Our data indicated that bacterial community is very dynamic and predator-prey dynamics shift transiently over short term potentially influenced by salinity, hydrology and sideways control factors such as obligate predation by Bdellovibrio and like organisms (BALOs).