Investigation of pathogenic bacterial transport by waterbirds: A case study of flooded and non-flooded rice systems in Mississippi

Authors: FIRTH, ALEXANDRA - Mississippi State University; BAKER, BETH - Mississippi State University; Brooks, John; Smith, Renotta; IGLAY, RAYMOND - Mississippi State University; DAVIS, J. - Mississippi State University

Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2020
Publication Date: 6/26/2020
Citation: Firth, A.G., Baker, B.H., Brooks, J.P., Smith, R.K., Iglay, R.B., Davis, J.B. 2020. Investigation of pathogenic bacterial transport by waterbirds: A case study of flooded and non-flooded rice systems in Mississippi. Water. 12:1833. https://doi.org/10.3390/w12061833.
DOI: https://doi.org/10.3390/w12061833

Interpretive Summary: Over wintering birds require water ways to feed and recover. One approach to promote this activity for either recreational or ecological purposes is to flood rice fields which would normally not be in use during the winter. Some rice systems in the Mississippi Alluvial Valley employ a low-external-input-sustainable-agriculture (LEISA) system where few external inputs are employed. This study compared a typical rice farm and these low input farms to determine the potential for bacterial contamination associated with these over wintering birds. We looked for fecal bacteria in soil before and after winter flooding to estimate the impact of birds on the field contamination. Water samples were tested for many of the same bacteria. One specific fecal bacteria was more often detected in the LEISA flooded fields compared with soil collected from the typical farm. All observed pathogens detections were below regulatory levels. Results suggest that long-term waterbird stopovers can influence pathogen indicators in soil, however not at a significant level to pose threat to human and environmental health standards.

Technical Abstract: Wintering waterbird use of flooded rice fields could facilitate pathogen transport in a low-external-input-sustainable-agriculture (LEISA) rice system in the Mississippi Alluvial Valley. We compared two rice farms with different management histories during the winter (conventional and LEISA) were selected for study and received two treatments: 1) unflooded or 2) winter flooded fields. Fecal indicator bacteria (Enterococci, Clostridium perfringens, Salmonella, Campylobacter and Escherichia coli.) were quantified in soil before and after winter flooding and bird fecal matter estimated. Water samples were tested for Enterococci, C. perfringens and E.coli before fields were drained. LEISA flooded fields had significantly greater detections of C. perfringens than conventional non-flooded fields in the soil. All observed pathogen rates between treatments were also less than EPA standards. Results suggest that long-term waterbird stopovers can influence pathogen indicators in soil, however not at a significant level to pose threat to human and environmental health standards. Future studies should focus on long-term monitoring of rice fields that harbor wintering birds for pathogen introduction.