Factors Determining E. coli Distribution in Nearshore Lake Malawi

Session: 27. - Emerging Partnerships, Research, and Capacity in the African Great Lakes

Emily Tyner, University of Wisconsin-Milwaukee, [email protected]
Phoebe Jensen, Tulane University School of Medicine, [email protected]
Maxon Ngochera, Monkey Bay Fisheries Research Station, [email protected]
Harvey Bootsma, University of Wisconsin-Milwaukee, [email protected]

Abstract

Residents along the shoreline of Lake Malawi depend on nearshore water for drinking, cooking, and bathing. Despite the importance of nearshore waters, there are no published studies of biologic contaminants in shoreline water. To address this gap, we explored spatial and temporal trends of the fecal indicator bacteria Escherichia coli (E. coli) in water and sand at beaches along the southeastern and southwestern arms of Lake Malawi. We found that 91% of water samples exceed the World Health Organization threshold for safe drinking water and 57% exceed the U.S. EPA standard for recreation. We identify beach use as the variable most predictive of E. coli concentrations in water. While shoreline water is frequently contaminated, concentration declined with distance from shore. For example, at 15 meters from the shore, concentrations dropped to between 0.3% and 17% of shoreline values, suggesting that collection of drinking water at distances greater than 15 meters from shore could substantially decrease exposure to pathogens. Future studies should use microbial source tracking to identify sources (i.e. human, cattle, bird) of fecal pollution in the lake. To our knowledge this paper presents the first known assessment of nearshore E. coli concentrations in Lake Malawi. 

1. Keyword
Lake Malawi

2. Keyword
drinking water

3. Keyword
human health

4. Additional Keyword
E. coli

5. Additional Keyword
biologic contaminants