Quantitative multi-year elucidation of fecal sources of waterborne pathogen contamination in the South Nation River basin using Bacteroidales microbial source tracking markers.

Marti, R., Gannon, V.P.J., Jokinen, C.C., Lanthier, M., Lapen, D.R., Neumann, N.F., Ruecker, N.J., Scott, A., Wilkes, G.A., Zhang, Y., and Topp, E. (2013). "Quantitative multi-year elucidation of fecal sources of waterborne pathogen contamination in the South Nation River basin using Bacteroidales microbial source tracking markers.", Water Research, 47(7), pp. 2315-2324. doi : 10.1016/j.watres.2013.02.009  Access to full text

Abstract

Over a seven-year period (2004-2010) 1095 water samples wereobtained from the South Nation river basin at multiple watershed monitoring sites (Ontario, Canada). Real-time PCR using Bacteroidales specific markers was used to identify the origin (human (10% prevalence), ruminant (22%), pig (∼2%), Canada goose (4%) and muskrat (7%)) of fecal pollution. In parallel, the distribution of fecal indicator bacteria and waterborne pathogens (Cryptosporidium oocysts, Giardia cysts, Escherichia coli O157:H7, Salmonella enterica and Campylobacter spp.) was evaluated. Associations between the detection of specific Bacteroidalesmarkers and the presence of fecal indicator bacteria, pathogens, and distinctland use or environmental variables were evaluated. Linear correlations between Bacteroidales markers and fecal indicator bacteria were weak. However, mean marker densities, and the presence and absence of markers could be discriminated on the basis of threshold fecal indicator densities. The ruminant-specific Bacteroidales marker was the most frequently detected marker in water, consistent with the large number of dairy farms in the study area. Detection of the human or the ruminant markers were associated with a slightly higher risk of detecting Salmonella enterica. Detection of the muskrat/vole marker was related to more frequentCampylobacter spp. detections. Important positive associations between markers and pathogens were found among: i) total Bacteroidales andCryptosporidium and Giardia, ii) ruminant marker and S. enterica, and iii) muskrat and Campylobacter spp.

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