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Impacts of land management practices on stream microbial loading in Northeast GA
Citation:
Oladeinde, A., R. Brown, C. Fitzgerald, KELVIN WONG, G. Myrthill, AND M. MOLINA. Impacts of land management practices on stream microbial loading in Northeast GA. Presented at 83rd Annual Meeting & Conference of the Georgia Public Health Association, Atlanta, GA, April 12 - 14, 2012.
Impact/Purpose:
Abstract for GA Public Health Association. April 12-14; Atlanta, GA
Description:
Identification of dominant source(s) of fecal pollution in a watershed is necessary for assessing the safety of recreational water and for protecting water resources. The objective of this study was to examine the relative abundance of molecular fecal markers from two cattle farms in Northeast Georgia. The farms employ two different management practices; Farm A uses rotational grazing while Farm B has no land management practice in place. Cultural and molecular methods were used to detect the presence of Salmonella and to quantify fecal indicator bacteria and a cow-specific microbial source tracking marker (MST) in farm streams for 18 months during baseflow and rain events. Salmonella was detected 96% of the time at both farms. An exceedance curve demonstrated that 95% of baseflow samples from Farm A exceeded EPA’s infrequent contact standards for enterococci and 100% in Farm B. Farm A had similar mean culturable enterocci concentration, high mean enterococci quantitative polymerase chain reaction (qPCR) marker concentration (P<0.0001), and lower mean cow-specific marker concentration than Farm B (P<0.0001). During baseflow, the stream in Farm B exhibited a significantly higher (P<0.0001) daily loading rate than the stream in Farm A for culturable enterococci (19.1 vs 6.9 x109 enterococci/day) and cow specific marker (167 vs 3.95 x109 TSC/day). No significant difference (p>0.05) was identified in the loading rates during rain events. The assessment of a cow specific marker in conjunction with traditional enterococci and fecal coliform bacteria levels will allow better insight on the source of water contamination and the determination of immediate public health risks.
