Florida cattle decay study

Fecal contamination of recreational waters with cattle manure can pose a risk to public health due to the potential presence of various zoonotic pathogens. Fecal indicator bacteria (FIB) have a long history of use in the assessment. However, FIB quantification provides no information about pollution sources. Microbial source tracking (MST) genetic markers have been developed in response to a need to identify pollution sources, yet factors that influence host-identifier target decay once discharged into the environment are often poorly understood, especially for agriculture fecal waste sources. Here, we investigate the influence of water type (freshwater versus marine) and select environmental parameters (indigenous microbiota, ambient sunlight) on the decay of FIB and MST genetic markers originating from cattle manure. Experiments were conducted in situ using a submersible aquatic mesocosm containing dialysis bags filled with a mixture of cattle manure and ambient water. Culturable FIB (E. coli and enterococci) were enumerated by membrane filtration and the concentration of general fecal indicator bacteria (GenBac3, Entero1a, and EC23S857) and MST (Rum2Bac, CowM2, and CowM3) genetic markers were estimated by qPCR. Water type was the most significant factor influencing the decay of cattle manure indicator bacteria (three-way ANOVA, p: 0.006 to < 0.001), although the magnitude of the effect differed among microbial targets and over time. The presence of indigenous microbiota and exposure to sunlight were both significantly correlated (three-way ANOVA, p: 0.044 to < 0.001) with decay of enterococci and CowM2, while E. coli, EC23S857, Rum2Bac, and CowM3 (three-way ANOVA, p: 0.044 144 hours) of both cultivated FIB and genetic markers in marine and freshwater water types. Findings suggest that multiple environmental stressors are important determinants of FIB and MST marker persistence, but their magnitude can vary across different indicators. Selective exclusion of natural aquatic microbiota and/or sunlight typically resulted in extended survival, but the effect was minor and limited to select microbial targets.

This dataset is associated with the following publication: Korajkic, A., B. McMinn, N. Ashbolt, M. Sivaganesan, V. Harwood, and O. Shanks. Extended persistence of general and cattle-associated fecal indicators in marine and freshwater environment. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, NETHERLANDS, 650(1): 1292-1302, (2018).