Examining the Colonization and Survival of E. Coli from Varying Host Sources in Drainage Basin Sediments and Stormwater

It is widely understood that stormwater drainage has a significant impact on the health of tidal creek systems via regular inputs of runoff from the surrounding watershed. Due to this hydrologic connection, contamination of the upstream drainage basin will have a direct effect on estuaries and tidal creeks that often act as receiving waters. This study focuses on the importance of drainage basin sediments as they enhance the persistence and transport of the fecal indicator bacteria E. coli within a watershed. Experiments presented use microcosm environments with drainage basin sediments and stormwater to investigate E. coli colonization of stagnant waters and to examine the importance of host sources to bacterial survival. A novel method for establishing microcosms using environmental sediments with in situ bacterial populations and sterile overlying waters is used to examine E. coli colonization of the water column in the absence of flow. Colonization of sterile sediment environments also is examined using two common host sources (human and avian). Each experiment uses sediments of varying grain size and organic content to examine the influence of physical characteristics on bacterial prevalence. Results suggest host source of bacteria may be more important to initial bacterial colonization while physical characteristics of drainage basin sediments better explains extended E. coli persistence. Findings also suggest an indirect control of water column bacterial concentration by sediment type and erodibility.