Microbial Find, Inform, and Test Model for Identifying Spatially Distributed Contamination Sources: Framework Foundation and Demonstration of Ruminant Bacteroides Abundance in River Sediments

Microbial pollution in rivers poses known ecological and health risks, yet causal mechanistic linkages to sources remain difficult establish. Host-associated microbial source tracking (MST) markers help assess the risks by linking hosts contamination but do not identify locations. Land-use regression (LUR) models have been used screen locations using spatial predictors could be improved characterizing transport (i.e., hauling, decay overland, downstream). We introduce Find, Inform, Test (FIT) framework, which expands previous LUR approaches develops novel predictor characterize transported contributions. applied FIT of BoBac, a ruminant Bacteroides MST marker, quantified riverbed sediment samples from Kewaunee County, Wisconsin. A 1 standard deviation increase contributions land-applied manure hauled animal feeding operations (AFOs) was associated with 77% (p-value <0.05) relative abundance (BoBac-copies-per-16S-rRNA-copies) sediment. This is first work finding an association between upstream offsite bovine-associated fecal markers. These findings implications for as reservoir AFOs (e.g., pathogens antibiotic-resistant bacteria). framework application advance statistical analysis water quality modeling more broadly.