Stream pathogenic bacteria levels rebound post-population control of wild pigs

Area of Science:

• Environmental Science
• Wildlife Ecology
• Public Health

Background:

• Invasive wild pigs (Sus scrofa) are expanding in North America.
• Wild pig feces contaminate surface waters, increasing pathogenic bacteria and zoonotic disease risk.
• Water quality improvements occur after wild pig population control, but the duration is unknown.

Purpose of the Study:

• To determine the longevity of water quality remediation after wild pig population control.
• To assess the impact of wild pig population rebound on water quality.
• To evaluate public health risks associated with wild pig fecal contamination.

Main Methods:

• Monitoring of Escherichia coli and fecal coliform concentrations in surface waters.
• Comparison of water quality metrics before, during, and after wild pig removal efforts.
• Analysis of public health risk by tracking exceedances of bacterial guidelines.

Main Results:

• Median Escherichia coli and fecal coliform concentrations increased significantly (746% and 159%) in the year after removal efforts concluded.
• Bacterial concentrations exceeded pre-removal levels, indicating a return of contamination.
• Public health risks increased, with more frequent exceedances of E. coli (10%) and fecal coliform (12%) guidelines.

Conclusions:

• Water quality remediation benefits from wild pig control are not permanent.
• Wild pig population rebound leads to a resurgence of water contamination and public health risks.
• Ongoing wild pig population control is likely necessary to sustain water quality improvements and mitigate health risks.