USING MOLECULAR TOOLS AND MICROBIOLOGY TESTING TO STUDY THE IMPACT OF HURRICANE HANNA ON MICROBIAL CONTAMINATION IN SOUTH TEXAS WATER RESOURCES

Hurricane Hanna occurred in south Texas in Summer 2020 and caused flooding in Baffin Bay and Rio Grande Valley. Fecal indicator bacteria and other pollutants (e.g., fertilizers, pesticides, hydrocarbons, heavy metals, etc.) are transported to the surface and ground waters. The increased pathogenic activities negatively impact on animals and can severely compromise human health if ingested.

This study investigates the microbial contamination in surface and well waters followed by hurricane Hanna over a period of approximately one year. For that purpose, samples were collected from surface waters and wells in 1-liter autoclaved Nalgene® bottles. Samples were brought to the lab and filtered using filter papers and stored in -80 °C for qPCR assays. 100 mL of samples were also subjected to IDEXX colilert analysis and incubated at 35 °C for 24 hours to obtain total coliform and E-coli concentrations.

Results from qPCR and IDEXX assays indicated higher levels of E-coli in surface waters after the hurricane landfall, possibly due to overflowing of septic tanks. Results from IDEXX assays showed highly contaminated surface waters with fecal indicator bacteria and lower contamination in well samples. Human fecal contamination was also investigated. Except for few sites which showed very low concentration of the HF183 marker in qPCR, all others were negative. Enterococcus contamination was analyzed using the Entero1 universal marker. Surface water showed high contamination of enterococcus, while lower contamination was observed in well samples. Future research will focus on identifying sources of contamination specifically in surface waters to recommend solutions in order to protect drinking water resources. The result from this study is not only beneficial to investigate the effects of hurricane Hanna on microbial contamination, but also benefits the research on the impact of any storm events leading to high flooding.