Most coastal freshwater ecosystems in the United States have semi-tidal movements during the day. Routine monitoring of these environments is conducted once during the day when tides can be at either ebb or flood conditions, causing variability in bacterial concentrations and misinterpretation of the illness risk associated with human activities. In this study, the occurrence and levels of enterococci (enterococci 23S rDNA [Ent23S]) and human- (HF183) and avian- (GFD) associated microbial source tracking (MST) markers were investigated during the ebb and flow tide conditions at an inland beach used mainly for fishing purposes by low-income families. Results showed that unlike the general assumption that ebb tide flow in a river would likely carry pollutants via runoff from the land, the microbial contaminants, in this case, were transported from upstream from ocean water to the river during the flood tide. These results suggest that hydrology and land use patterns must be considered in sampling design when conducting future microbial water quality monitoring programs to characterize recreational water safety in tidal rivers better.
“The Impact of Tides on Microbial Water Quality at an Inland River Beach” was recently published in the Journal of Environmental Quality.
Dr. Asli Aslan, assistant professor of environmental health sciences at the Georgia Southern University Jiann-Ping Hsu College of Public Health was the lead author, with her students Mr. Kendall W. Anderson and Ms. Asheley Chapman as co-authors.