Microbial Source Tracking in the Love Creek Watershed, Delaware (USA)

Area of Science:

• Environmental microbiology
• Water quality monitoring
• Bioinformatics

Background:

• Fecal contamination of waterways is a significant environmental and public health issue in Delaware.
• Enterococcus bacteria are used by the state to monitor fecal pollution and set recreational water quality standards.

Purpose of the Study:

• To investigate the sources of fecal contamination in the Love Creek watershed, a tributary of Rehoboth Bay.
• To compare bacterial communities with chemical and nutrient concentrations to understand contamination drivers.

Main Methods:

• Utilized next-generation sequencing and SourceTracker analysis for microbial source tracking.
• Developed a fecal library from ten animal types and one human sample for comparative analysis.
• Assessed the correlation between bacterial community composition and environmental factors like orthophosphate and total dissolved solids.

Main Results:

• Orthophosphate and total dissolved solids were identified as major factors influencing bacterial community composition.
• SourceTracker analysis revealed that the majority of microbial communities originated from "unknown" sources, primarily wildlife.
• Known sources of contamination were predominantly domestic animals, specifically cats and dogs.

Conclusions:

• The applied methods demonstrate capability for initiating fecal source tracking at the state level.
• Understanding microbial sources is crucial for effective management of bacterial contamination in waterways.
• Wildlife and domestic animal waste are significant contributors to fecal pollution in the Love Creek watershed.