Spatial Variability of Escherichia coli in Rivers of Northern Coastal Ecuador

Abstract

The use of contaminated surface water continues to be a pressing issue in areas of the world where people lack improved drinking water sources. In northern coastal Ecuador, many communities rely on untreated surface water as their primary source of drinking water. We undertook a study to explore how microscale river hydrodynamics affect microbial water quality at community water collection locations at three rivers with varying stream velocity and turbidity profiles. To examine how the distance from river shore and physiochemical water quality variables affect microbial contamination levels in the rivers; we collected a total of 355 water samples within six villages on three rivers; and tested for Escherichia coli concentrations using the IDEXX Quanti-tray method. We found that log10 E. coli concentrations decreased with increasing distance from shore (β = −0.017; p = 0.003). Water in the main channel had E. coli concentrations on average 0.12 log10 lower than within eddies along the river shore and 0.27 log10 lower between the sample closest to shore and any sample >6 m from the shore. Higher E. coli concentrations were also significantly associated with increased turbidity (β = 0.003; p < 0.0001) and decreased dissolved oxygen levels (β = −0.310; p < 0.0001). The results of this study can help inform community members about the safest locations to collect drinking water and also provide information on watershed scale transport of microbial contaminants between villages.

Complex interactions between weather, and microbial and physiochemical water quality impact the likelihood of detecting foodborne pathogens in agricultural water

“…For example, turbidity was ranked as an important factor in 7 of the 15 random forest analyses performed here, and was associated detecting pathogens in samples collected from both AZ and NY waterways. Multiple studies (Christensen et al, 2000; Francy et al, 2013; Havelaar et al, 2017; Horman et al, 2004; Nagels et al, 2002; Rao et al, 2015; Topalcengiz et al, 2017), including the study reported here and the Ecuadorian study discussed above (Rao et al, 2015), found a positive association between E. coli levels and temperature, or between E. coli levels and turbidity. Francy et al (Francy et al, 2013) surveyed recreational water quality at 22 Ohio beaches along inland lakes and found that turbidity was one of the best predictors of E. coli levels.…”

“…This suggests that E. coli levels were more strongly associated with physiochemical water quality than weather for the waterways sampled during our study. Previous studies have repeatedly identified associations between physiochemical water quality and E. coli levels (Ansa et al, 2011; Christensen et al, 2000; Horman et al, 2004; Rao et al, 2015; Roslev et al, 2004; Stocker et al, 2016). Similar to our study, a study that examined the microbial and physiochemical quality of three Ecuadorian rivers found a negative association between dissolved oxygen and E. coli levels (Rao et al, 2015).…”

“…Previous studies have repeatedly identified associations between physiochemical water quality and E. coli levels (Ansa et al, 2011; Christensen et al, 2000; Horman et al, 2004; Rao et al, 2015; Roslev et al, 2004; Stocker et al, 2016). Similar to our study, a study that examined the microbial and physiochemical quality of three Ecuadorian rivers found a negative association between dissolved oxygen and E. coli levels (Rao et al, 2015). A potential explanation for the inverse relationship between dissolved oxygen and E. coli levels is that the ability of UV radiation to damage bacterial cells is positively associated with dissolved oxygen (Ansa et al, 2011; Curtis et al, 1992; Davies-Colley et al, 1997; Ouali et al, 2014).…”

Reducing Escherichia Coli Contamination on Dringking Water Stations in Pasuruan, East Java, Indonesia.

“…The widespread of E. coli population was poorly recorded and studied in Pasuruan. Rao et al (2015) found the way to inform community members about the safest locations to get drinking water and watershed scale transport of microbial contaminants/ between villages [8]. Recently, people take the drinking water from drinking water station.…”

Potencial de plantas acuáticas para la remoción de coliformes totales y Escherichia coli en aguas negras

“…En el Ecuador existen comunidades que dependen del agua superficial no tratada como su fuente primaria de agua potable (Rao et al, 2015). Lamentablemente, estas fuentes superficiales son el sumidero de aguas servidas que contienen residuos humanos con una gran carga bacteriana, en especial de coliformes fecales.…”