Coliform bacteria in San Pedro Lake, western Mexico

Abstract

Urbanization, livestock activities, and rainfall are factors that contribute to the contamination of inland water. This study aimed to determine the spatial and temporal variability of total coliforms (TCs) and fecal coliforms (FCs) in the surface water of San Pedro Lake as well as the gills and skin of Nile tilapia (Oreochromis niloticus) cultivated in the lake. The study consisted of seasonal sampling during an annual cycle. Using the multiple‐tube fermentation technique, we quantified the microbial load of TCs in the lake and fish. The median of the TC and FC groups in surface water showed differences during the seasonal cycle, in which a significant correlation was observed between rainfall and bacterial load in the lake surface water. There was a significant seasonal difference between FCs and TCs in the gills as well as in skin FCs. Anthropogenic activities in the watershed combined with rainfall influence the bacterial load of San Pedro Lake. However, the water quality is still classified as excellent and uncontaminated according to Mexican regulations with lower FC values acceptable for higher FC values. In addition, the bacterial load in tilapia from San Pedro Lake does not pose a risk to human health. Practitioner points Watershed livestock activities combined with rainfall increase fecal matter pollution in specific areas of the lake. San Pedro Lake displays satisfactory quality for aquatic life. The median fecal coliform population in lake fish (gills and skin) differs by season.

A preliminary evaluation of microbial water quality in the irrigation pond

“…Our results suggest that surface runoff, even after light rainfall (<2.5 mm of rain) is major driver which contributing diffuse pollution both in surface and bottom waters in the pond. This result is consistent with previous studies reported positive correlation between coliform bacteria and rainfall events at lake and pond ecosystems (An et al, 2002; Jeon et al, 2019; Moshi et al, 2022; Ramos‐Ramírez et al, 2020; Staley et al, 2012; Staley et al, 2013; Stocker et al, 2019; Tryland et al, 2011; Xue et al, 2018). On the other hand, few studies reported no significant relationship between fecal indicator bacteria and rainfall (Nguyen et al, 2016; Sampson et al, 2006).…”

High microbiological contamination in surface waters in the upper basin of the Choluteca River in Honduras

“…For this reason, E. coli is an accurate indicator of fecal contamination due to its constant presence in the intestine and feces of warm-blooded animals. The presence of TtC in any body of water has a high predictive value for the potential presence of other pathogenic microorganisms for humans [19][20][21]30 . On the other hand, it has been suggested that the presence of IE might be used as a supplementary test for assessing water quality.…”

“…Traditionally, bacteriological markers have been used to monitor and verify the quality of water intended for human use and consumption, including the presence and count of total coliforms (TC), thermotolerant coliforms (TtC) and intestinal enterococci (IE) [15][16][17][18] . Among the thermotolerant coliforms, Escherichia coli has been considered the most robust fecal indicator 15,16,[19][20][21] . Furthermore, the phylogenetic distribution of E. coli has been suggested as a complementary analysis to help better understand its presence in waters 17 .…”

Evaluation of Water and Sediment Quality by Bacteriological Diversity Studies on Certain Locations of the Diyala River, Baghdad

“…Commonly used indicators include coliform bacteria, which may have been reduced from total coliform to fecal coliform and faecal Streptococci (Kistemann et al, 2002). Commonly used indicators include coliforms, which may have been reduced from total coliforms to faecal coliforms and faecal Streptococci (Messner et al, 2017;Ramos-Ramírez et al, 2020).…”