Human and Bovine Virus Prevalence in Some Great Lakes Tributaries Influenced by Watershed-Specific and Seasonal Characteristics

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Human enteric and bovine-specific viruses were detected in eight Great Lakes tributaries. Presence and concentration of human viruses increased in watersheds with greater than 25 percent urban influence and more than 2,900 people per square kilometer. Similarly, bovine viruses increased in watersheds having greater than 40 percent agricultural land influence and cattle densities greater than 50 cattle per square kilometer.

Viruses Great Lakes Streams

An artistic illustration depicting the complex and various transport pathways for human and bovine viruses to contaminate surface water. Illustration Credit: Benjamin Siebers, USGS. 

The detection of human and bovine viruses in surface water indicates the presence of fecal contamination. Fecal contamination from humans and cattle can pose risks to the health of humans, wildlife, and livestock. Urban and agricultural areas, each with their own unique set of watershed characteristics, contributed human and bovine viruses by way of various transport pathways to Great Lakes tributaries.

In this study, human and bovine viruses were measured in eight Great Lakes streams to examine the variability of pathogen presence in relation to changing hydrologic condition, season, and land cover composition. Scientists determined the presence and concentration of human and bovine viruses from 290 surface water samples (189 runoff and 101 low-flow samples) collected during a 29-month period from February 2011 to June 2013. A custom-automated-pathogen sampler provided a flow-weighted sampling strategy that collected water for 24 hours during low-flow periods and throughout the runoff hydrograph during rainfall and snowmelt events. Samples were analyzed by quantitative polymerase chain reaction (qPCR) for a suite of human and bovine viruses.

Results of this study indicate waterborne pathogen prevalence, concentration, and flux are influenced by virus sources, land cover, and seasonal characteristics, but the degree of influence of these characteristics varied by sampling location, likely due to the source-specific differences among the watersheds studied. These results are useful to resource managers developing science-based management strategies for pathogen reduction and indicate the need to consider individual watershed characteristics to better represent the diversity of source-specific contributions.

A custom automated pathogen sampler and schematic illustration.

A photograph of U.S. Geological Survey (USGS) custom automated pathogen sampler (top) and schematic illustrating the remote-unattended-automated pathogen sampler (bottom). Sample collection proceeds over the course of a runoff-event or low-flow period for up to a maximum of 5 days before a site visit by personnel is needed to collect the samples.

(Credit: Pete Lenaker, USGS. Public domain.)

The Great Lakes Restoration Initiative provided the financial support for this research.

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