Long-term monitoring of waterborne pathogens and microbial source tracking markers in paired-agricultural watersheds under controlled and conventional tile drainage management.

Wilkes, G.A., Brassard, J., Edge, T.A., Gannon, V.P.J., Gottschall, N., Jokinen, C.C., Jones, T.H., Khan, I.U.H., Marti, R., Sunohara, M., Topp, E., and Lapen, D.R. (2014). "Long-term monitoring of waterborne pathogens and microbial source tracking markers in paired-agricultural watersheds under controlled and conventional tile drainage management.", Applied and Environmental Microbiology, 80(12), pp. 3708-3720. doi : 10.1128/AEM.00254-14  Access to full text

Abstract

Surface waters of a set of paired-agricultural watersheds under controlled tile drainage (CTD) and uncontrolled tile drainage (UCTD) were monitored over 7 years in order to determine if there was an effect of CTD (imposed during the growing season) on occurrences and loadings of bacterial and viral pathogens, coliphage, and microbial source tracking markers. There were significantly lower occurrences of human, ruminant, and livestock (ruminant+pig) Bacteroidales markers in the CTD watershed in relation to the UCTD watershed. As for pathogens, there were significantly lower occurrences of Salmonella spp. and Arcobacter spp. in the CTD watershed. There were no instances where there were significantly higher quantitative loadings of any microbial target in the CTD watershed, except for F-DNA and F-RNA coliphage, perhaps as a result of fecal inputs from a hobby farm independent of the drainage practice treatments. There was lower loading of the ruminant marker in the CTD watershed, in relation to the UCTD system, and results were significant at the p=0.06 level. The odds of Salmonella spp. occurring significantly increased when a ruminant marker was present, yet for Arcobacter spp., the odds of this pathogen occurring significantly decreased when a ruminant marker was present (but increased when a wildlife marker was present). Interestingly, the odds of norovirus GII (associated with human and swine) occurring in water increased significantly when a ruminant marker was present. Overall, this study suggests that exposure risks associated with fecal pollution from tile drained fields to stream, could be reduced by CTD utilization.

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