Quantitative multi-year elucidation of fecal sources of waterborne pathogen contamination in the South Nation River basin using Bacteroidales microbial source tracking markers Romain Marti a , Victor P.J. Gannon b , Cassandra Jokinen b , Martin Lanthier c , David R. Lapen c , Norman F. Neumann d,e , Norma J. Ruecker e,f , Andrew Scott a , Graham Wilkes c , Yun Zhang a , Edward Topp a, * a Agriculture and Agri-Food Canada, 1391 Sandford Str., London, Ontario N5V 4T3, Canada b Laboratory for Foodborne Zoonoses, Public Health Agency of Canada, PO Box 640, Township Road 9-1, Lethbridge, Alberta T1J 3Z4, Canada c Agriculture and Agri-Food Canada, Eastern Cereal and Oilseed Research Centre, Ottawa, Ontario K1A 0C6, Canada d School of Public Health, University of Alberta, Edmonton, Alberta, Canada e Alberta Provincial Laboratory for Public Health, 3030 Hospital Drive NW, Calgary, Alberta, Canada f Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada article info Article history: Received 17 October 2012 Received in revised form 30 January 2013 Accepted 2 February 2013 Available online 14 February 2013 Keywords: Agriculture Water quality Microbial source tracking abstract Over a seven-year period (2004e2010) 1095 water samples were obtained 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% preva- lence), ruminant (22%), pig (w2%), Canada goose (4%) and muskrat (7%)) of fecal pollution. In parallel, the distribution of fecal indicator bacteria and waterborne pathogens (Crypto- sporidium oocysts, Giardia cysts, Escherichia coli O157:H7, Salmonella enterica and Campylo- bacter spp.) was evaluated. Associations between the detection of specific Bacteroidales markers and the presence of fecal indicator bacteria, pathogens, and distinct land 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 S. enterica. Detection of the muskrat marker was related to more frequent Campylobacter spp. detections. Important positive associations between markers and pathogens were found among: i) total Bacteroidales and Cryptosporidium and Giardia, ii) ruminant marker and S. enterica, and iii) muskrat and Campylobacter spp. Crown Copyright ª 2013 Published by Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: þ1 519 457 1470x235; fax: þ1 519 457 3997. E-mail address: Ed.topp@agr.gc.ca (E. Topp). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/watres water research 47 (2013) 2315 e2324 0043-1354/$ e see front matter Crown Copyright ª 2013 Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.watres.2013.02.009