Assessment of chicken fecal contamination using microbial source of tracking (MST) and environmental DNA (eDNA) profiling in Silway River, Philippines

The effect of low velocity and physicochemical water quality parameters on chicken fecal contamination is Silway River [South Cotabato, Philippines] was studied. Microbial Source Tracking and Environmental DNA (eDNA) profiling were applied to evaluate the contamination of chicken fecal in Silway River. The relationship between chicken fecal contamination and physicochemical water quality parameters were also assessed. The dissolved oxygen, temperature, pH, turbidity, and flow velocity were measured in ten stations on April 14, 2023 from 8:00 am to 4:00 pm when the weather was sunny and clear. Flow velocity monitoring records is usually expensive and difficult to measure. Since velocity records are not available, it was measured using flow section method. Water samples were collected for chicken fecal contamination detection and quantification and for total suspended solids (TSS) analysis. The results of this study showed the presence of chicken fecal bacteria in several locations along the Silway River. MST method using Ckmito and ND5 markers are effective in detecting and quantifying chicken-specific fecal bacteria in water bodies. While most parameters align with acceptable standards, elevated TSS and turbidity level are noted at specific stations especially in Station 10, attributed to the study area's topography and runoff effects. Chicken fecal contamination and water quality parameters relationship suggests that normal level of DO, temperature, and pH along with high TSS concentration create favorable condition for chicken fecal coliforms to survive, contributing to the fecal contamination in Silway River. Relationship among water quality parameters and flow velocity was also studied. Flow velocity and TSS exhibited a positive linear relationship (R sup 2 = 0.653), suggesting the faster-moving contains higher TSS levels, while a positive linear relationships was observed between DO and pH (R sup 2 = 0.301). An inverse relationship is noted between temperature and DO implying colder water can hold more dissolved oxygen, while warmer water has lower DO levels. Turbidity serves as a proxy for estimating TSS levels and exhibits a strong positive linear relationship with it.