Hydrologic, land cover, and seasonal patterns of waterborne pathogens in Great Lakes tributaries

Abstract

Great Lakes tributaries are known to deliver waterborne pathogens from a host of sources. To examine the hydrologic, land cover, and seasonal patterns of waterborne pathogens (i.e. protozoa (2), pathogenic bacteria (4) human viruses, (8) and bovine viruses (8)) eight rivers were monitored in the Great Lakes Basin over 29 months from February 2011 to June 2013. Sampling locations represented a wide variety of land cover classes from urban to agriculture to forest. A custom automated pathogen sampler was deployed at eight sampling locations which provided unattended, flow-weighted, large-volume (120-1630 L) sampling. Human and bovine viruses and pathogenic bacteria were detected by real-time qPCR in 16%, 14%, and 1.4% of 290 samples collected while protozoa were never detected. The most frequently detected pathogens were: bovine polyomavirus (11%), and human adenovirus C, D, F (9%). Human and bovine viruses were present in 16.9% and 14.8% of runoff-event samples (n = 189) resulting from precipitation and snowmelt, and 13.9% and 12.9% of low-flow samples (n = 101), respectively, indicating multiple delivery mechanisms could be influential. Data indicated human and bovine virus prevalence was different depending on land cover within the watershed. Occurrence, concentration, and flux of human viruses were greatest in samples from the three sampling locations with greater than 25% urban influence than those with less than 25% urban influence. Similarly, occurrence, concentration, and flux of bovine viruses were greatest in samples from the two sampling locations with greater than 50 cattle/km than those with less than 50 cattle/km. In seasonal analysis, human and bovine viruses occurred more frequently in spring and winter seasons than during the fall and summer. Concentration, occurrence, and flux in the context of hydrologic condition, seasonality, and land use must be considered for each watershed individually to develop effective watershed management strategies for pathogen reduction.

Geospatial distribution of viromes in tropical freshwater ecosystems

“…The runoff from the surrounding areas can also bring specific bacteria, or other vectors and nutrients into the reservoirs and the tributaries (Tseng et al, 2013). Even though previous studies have shown the correlation between land use and water-borne viral pathogens (Corsi et al, 2014;Lenaker et al, 2017), ours is the first study correlating land use cover with the whole viral community, thus overcoming the limitations of investigating specific viruses and providing comprehensive information on the community structure with the relationship of land use cover.…”

“…The exception of reservoir 6 (explained in Results 3.1) suggested that drainage points could also be significant drivers in shaping the viral communities as well as land use cover and population density. Higher population density could result in high occurrence of human-related viruses (Lenaker et al, 2017). Here, the population density to some extent could reflect the hotspots of human-related viruses.…”

“…In the water cycle, agriculture brings excess nutrients and agricultural chemicals to surface waters, causing oxygen depletion and increasing algal blooms (Foley et al, 2005). Urbanization degrades water quality through surface runoff, and human pathogenic viruses have been detected more frequently in watersheds with dominant urban and agricultural land cover (Corsi et al, 2014;Lenaker et al, 2017). Furthermore, human expansion into wildlife habitats or construction of zoos and animal parks provide opportunities for humanwildlife interactions, thus, increasing the risk for the possible transmission of zoonotic viruses to human populations (Patz et al, 2008).…”

“…It is hypothesized that the environment surrounding these reservoirs may favor distinct viral predators and further change the viral community characterization. However, up till now, studies of land use impacts on the virome community in freshwater ecosystems are still limited as they mainly rely on traditional methodology (culture-based method or qPCR/RT-qPCR), which focuses on limited human virus targets without considering the whole picture of the viral community in the water environment (Corsi et al, 2014;Lenaker et al, 2017). To date, there is no systematic report focusing on the geospatial distribution and diversity of viromes in natural surface waters and how they may be impacted by human activities and the effect of different land use.…”

Fate and transport of manure associated microbial constituents in agroecosystems

“…In order to gain a deeper understanding of pathogen persistence and transport in the environment, recent studies have utilized genomic techniques, capable of direct pathogen detection (Wilkes et al, 2014;Lenaker et al, 2017). However, targeting species specific 16S rRNA gene targets, genes coding for known toxins or other pathogenic genetic markers require additional enrichment steps prior to running individual qPCR assays on samples.…”