Defining linkages between land-use, Salmonella, and Campylobacter in the Satilla River Basin (Georgia, USA)
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From August 2007 to August 2009 a study of the Satilla River Basin (SRB), a mixed-use rural watershed located in the coastal plain of southern Georgia (USA), was conducted to provide an understanding of landuse and existing water quality in these important surface waters. Watersheds were sampled that: 1) represent agricultural areas receiving poultry litter application, 2) agricultural areas with poultry houses and receiving poultry litter application, 3) reference areas with little or no agricultural activity, 4) a small watershed receiving direct discharge from a wastewater treatment plant (WWTP); and 5) larger watersheds on the main channel of the Satilla and Seventeen Mile River’s. Landuse differences were responsible water quality and nutrient variability. Eighty-three of the dissolved oxygen (DO) samples (35.78%, N=232) were below the Georgia Environmental Protection Division DO minimum, indicating that the SRB did not support its designated recreational use. Salmonella and Campylobacter were detected at all 13 sites monitored, and their prevalence varied by location (i.e., upstream vs. downstream of the WWTP). Pathogens were more frequently present among the sites with agricultural landuse and poultry production. Salmonella were recovered from 43% (129 of 299) of all samples. Salmonella serogroups identified were serogroup C (59%), B (14%), D (14%), and E (13%). Salmonella enterica serotype Montevideo (23%), Braenderup (14%) and Saint Paul (13%) were the most frequently detected of 16 different serotypes identified. Campylobacter were recovered from 62% (96 of 156) of all samples. C. jejuni (30%) was the most prevalent species detected followed by C. lari (22%), C. upsaliensis (11%), and C. coli (3%). Enterococci were reasonably predictive of Salmonella and Campylobacter presence; however 62% (80/129) of Salmonella were detected when E. coli were below EPA standards and 73% (70/96) of Campylobacter were detected when fecal coliforms were below EPA standards. These results highlight the drawback of the current fecal indicator system as proxies for enteric bacteria such as Salmonella and Campylobacter, which were highly prevalent in this area. This study indicates that these pathogens likely arise from numerous sources, including humans, and that there may be risk of human exposure through recreational contact.