Detecting Differences in Bacterial Metabolism in the Buffalo National River

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Each year, the Buffalo National River (BUFF) attracts 1.6 million visitors, many of whom enjoy recreational water activities. Since 2013, a confined animal feeding operation (CAFO) for swine has been operating on Big Creek, a BUFF tributary.

Figure 1. The Buffalo National River in Arkansas

Figure 1. The Buffalo National River in Arkansas. (Credit: Billy Justus, USGS. Public domain.)

The Science Issue and Relevance: Each year, the Buffalo National River (BUFF) attracts 1.6 million visitors, many of whom enjoy recreational water activities. Since 2013, a confined animal feeding operation (CAFO) for swine has been operating on Big Creek, a BUFF tributary. Research is needed to determine if BUFF water quality is being affected by the CAFO. Unintended consequences of a nearby CAFO might include eutrophication and alterations in dissolved oxygen in water; introductions of antibiotics, antibiotic-resistant microbes, or pharmaceuticals; growth of nuisance algae affecting the river’s aesthetic appeal; and human health risks due to associated toxins produced by harmful algal blooms or bacterial exposure.

Methodology for Addressing the Issue: Ecological parameters are being documented at six sites along a gradient, upstream and downstream of the CAFO on the BUFF. Monthly water sampling and quarterly periphyton data (benthic algae and diatom taxa) are being compiled in 2017 and 2018. In addition to nutrients, dissolved oxygen and other, biological endpoints include periphyton, counts of Escherichia coli and other enteric bacteria, and bacterial metabolic activity. Periphyton are reflective of nutrient concentrations; E. coli strains can be potential human pathogens; and nutrients and chemical mixtures in the water influence bacterial metabolism and growth capabilities. Water samples collected over a course of two days are overnighted to the WARC laboratory in Lafayette, Louisiana. The WARC laboratory uses a fluorescent staining technique with flow cytometry to measure bacterial esterases, enzymes that reflect physiological activity and shown to be more active in impaired waterways. To concentrate the bacterial populations, the samples are filtered, bacteria are double-stained with 6-carboxyfloruoescein diacetate (CFDA) and propidium iodide (PI) and then analyzed, and total bacteria grown and colonies counted. Data will be assembled and analyzed to indicate ecological conditions across space and time. Levels of culturable E. coli and other bacteria, along with bacterial cellular activity, and nutrient concentrations will reflect the ecological conditions in the BUFF. Information from the study can be used by BUFF managers to ensure visitor safety.

Figure 2. Filtering river water in the laboratory.

Figure 2. Filtering river water in the laboratory. (Public domain.)

Future Steps: To work with BUFF to integrate all data sets, including USEPA-mandated data and other ecological variables. Assembling and analyzing the multiple data sets will inform managers and subsequently the general public about river condition in relation to the CAFO.