Are anglers exposed to Escherichia coli from an agriculturally impacted river?

ABSTRACT

The Pine River, in the central, Lower Peninsula region of Michigan, has a long history of contamination. Livestock facilities and manure application sites along the Pine River and its tributaries have led to elevated nutrient levels. In addition to nutrient loading and associated low levels of dissolved oxygen, the presence Escherichia coli bacteria have caused environmental and human health concerns. According to the Michigan Department of Health and Human Services, and the Michigan Department of Environment, Great Lakes, and Energy, E. coli counts in summer months consistently have exceeded safe levels for human contact since 2005. Though it is recommended that residents do not swim in the Pine River, there are no specific restrictions on recreational fishing which is prevalent. Few studies have evaluated whether or not E. coli accumulates in the mucus of fish and, if so, whether that provides a viable route of E. coli exposure for anglers. This study first evaluated the presence of fecal coliform and E. coli bacteria on hatchery-raised caged fish placed in the river as well as resident fish. Results showed that fecal coliform and E. coli bacteria accumulated both on caged and resident fish. This result led to further testing showing E. coli to be found on anglers' hands whether or not they handled or interacted with resident fish. This study suggests that fishing in rivers with heavy bacterial loading from agricultural runoff may expose anglers to potentially harmful E. coli.