Hydrodynamical effects on spatial distribution of enteric bacteria in the Jordan River-Lake Kinneret contact zone

Characteristics of bacterial community structure in the sediment of Chishui River (China) and the response to environmental factors

Sediment microorganisms performed an essential function in the biogeochemical cycle of aquatic ecosystems, and their structural composition was closely related to environmental carrying capacity and water quality. In this study, the Chishui River (Renhuai section) was selected as the research area, and the concentrations of environmental factors in the water and sediment were detected. High⁃throughput sequencing was adopted to reveal the characteristics of bacterial community structures in the sediment. In addition, the response of bacteria to environmental factors was explored statistically. Meanwhile, the functional characteristics of bacterial were also analyzed based on the KEGG database. The results showed that the concentration of environmental factors in the water and sediment displayed spatial differences, with the overall trend of midstream > downstream > upstream, which was related to the wastewater discharge from the Moutai town in the midstream directly. Proteobacteria was the most dominant phylum in the sediment, with the relative abundance ranged from 52.06% to 70.53%. The distribution of genus-level bacteria with different metabolic activities varied in the sediment. Upstream was dominated by Massilia, Acinetobacter, and Thermomonas. In the midstream, Acinetobacter, Cloacibacterium and Comamonas were the main genus. Nevertheless, the abundance of Lysobacter, Arenimonas and Thermomonas was higher in the downstream. Redundancy analysis (RDA) showed that total nitrogen (TN) and total phosphorus (TP) were the main environmental factors which affected the structure of bacterial communities in sediment, while total organic carbon (TOC) was the secondary. The bacterial community was primarily associated with six biological pathway categories such as metabolism. Carbohydrate metabolism and amino acid metabolism were the most active functions in the 31 subfunctions. This study could contribute to the understanding of the structural composition and driving forces of bacteria in the sediment, which might benefit for the ecological protection of Chishui River.

Scientific contagion heuristic: Judgments about the acceptability of water for religious use after potential scientific treatment

We propose the concept of ‘scientific contagion’ — a mental heuristic through which any form of scientific treatment transfers some essence of ‘science’ to the processed substance, thereby affecting its nature and social acceptability. This was tested regarding the potential treatment of water from natural sources before it is used for religious purposes, as many such sources have dangerous pollutants. For an ancient natural well having a religious narrative, most participants judged that the acceptability of water would be reduced for religious purposes but not for drinking if local officials scientifically treat the water. That is not the case if religious rituals are conducted on the water instead (Study 1). If water from a “holy river” is processed scientifically, most participants predicted that it would reduce acceptability for religious use while increasing acceptability for drinking (Study 2). Potential scientific treatment without altering the composition of water from a natural spring also decreased acceptability for religious use but there was no effect on acceptability for drinking or on willingness to pay money for the water (Study 3). A follow-up study comparing acceptability for different kinds of water sources — from a holy well, natural spring, and household tap water sourced from either underground wells or rivers found lower acceptability for religious usage compared to drinking after potential scientific treatment for all these waters, but more so for holy and natural waters (Study 4). These studies establish the phenomena of scientific contagion that could have significant social implications and open future directions.

Sediment bacterial communities in a eutrophic lake influenced by multiple inflow-rivers

Sediment bacterial communities are sensitive to environmental fluctuations, particularly external input sources. Studying the relationships between bacterial community distribution and the estuarine environment is critical for understanding the river-lake confluence ecosystem and the effect of inflow-rivers on lakes. In the present study, bacterial communities from the sediments of 14 estuaries and four pelagic sites of the Taihu Lake were investigated via high-throughput sequencing. The results demonstrated that Delta-, Beta-, and Gamma-proteobacteria, Acidobacteria, Nitrospira, Bacilli, Anaerolineae, and Actinobacteria were the major classes in sediment bacterial communities of the Taihu Lake. In general, the inflow-rivers of different pollution types have distinctly different influences on sediment bacterial communities of the lake. The bacterial community composition and physicochemical properties of pelagic sites were closer to those of the estuaries of western region which was polluted by serious industrial and agricultural pollution. The bacterial community diversity of estuaries was lower than those of pelagic sites. Spearman correlation analysis indicated that α-diversity of the bacterial community was significantly correlated with C/N, total nitrogen, and total carbon in estuarine sediments. Redundancy analysis revealed that the variance in bacterial community composition was also significantly associated with C/N (24.9%) followed by total phosphorus (15.8%), nitrite (7.2%), and nitrate (7.7%) among different estuaries. This study provides a reference to understand the influence of inflow-rivers on the lake ecosystem, which offered a basic guidance for maintaining the ecological system and protecting the water environment of lacustrine basin.

Modeling the Effects of Hydrodynamic Regimes on Microbial Communities within Fluvial Biofilms: Combining Deterministic and Stochastic Processes

To fully understand the effects of hydrodynamics on a microbial community, the roles of niche-based and neutral processes must be considered in a mathematical model. To this end, a two-dimensional model combining mechanisms of immigration, dispersal, and niche differentiation was first established to describe the effects of hydrodynamics on bacterial communities within fluvial biofilms. Deterministic factors of the model were identified via the calculation of Spearman's rank correlation coefficients between parameters of hydrodynamics and the bacterial community. It was found that turbulent kinetic energy and turbulent intensity were considered as a set of reasonable predictors of community composition, whereas flow velocity and turbulent intensity can be combined together to predict biofilm bacterial biomass. According to the modeling result, the bacterial community could get its favorable assembly condition with a flow velocity ranging from 0.041 to 0.061 m/s. However, the driving force for biofilm community assembly changed with the local hydrodynamics. Individuals reproduction within the biofilm was the main driving force with flow velocity less than 0.05 m/s, while cell migration played a much more important role with velocity larger than 0.05 m/s. The developed model could be considered as a useful tool for improving the technologies of water environment protection and remediation.

Determining the footprint of sewage discharges in a coastal lagoon in South-Western Europe

Ria Formosa is a highly productive lagoon in South-Western Europe, supporting 90% of Portuguese clam production. Decreases in shellfish production have been ascribed to deterioration of water quality due to sewage discharges. Nevertheless, a thorough study considering their impact on the whole lagoon system has been missing. This work determined the sewage footprint from the major sewage treatment plants (STP) regarding eutrophication and microbial contamination within a two-year monitoring program. This focused on salinity, oxygen, nutrients, chlorophyll-a and faecal coliforms. Areas closer to sewage discharges showed an evident impact with maximum effects detected at the major STP. However, globally, the Ria Formosa did not show clear eutrophication problems due to high tidal flushing. Ammonium, oxygen, chlorophyll-a and faecal coliforms, unlike the other parameters, showed no seasonality. Microbiological contamination was of great concern and public health issues could be avoided by settling shellfish beds at least 500 m away from discharge points.

Distribution of indicator bacteria in Canyon Lake, California

The spatial and temporal distributions of indicator bacteria in a small, multiple-use source drinking water reservoir in Southern California, USA were quantified over the period August 2001-July 2002. High levels of total and fecal coliform bacteria were present in Canyon Lake (annual geometric mean concentrations+/-SEM of 3.93+/-0.02 and 3.02+/-0.03 log cfu/100mL, respectively), while comparatively low levels of enterococci and E. coli were found (1.16+/-0.02 log cfu/100mL and 0.30+/-0.03 log MPN/100mL, respectively). As a result, these different indicator bacteria yielded quite divergent indices of water quality, with 72.1% of all surface samples (n=294) exceeding the USEPA single-sample limit of 400 cfu/100mL fecal coliform bacteria, while none (0%) of the samples exceeded the single-sample limit for E. coli (n=194). Regression analyses found a positive correlation between total and fecal coliform bacteria (R=0.50, significant at p<0.001) and between enterococci and E. coli (R=0.51, significant at p<0.001), but no correlation or inverse correlations were found between coliform concentrations and enterococci and E. coli levels. External sources responsible for the high total and fecal coliform bacteria were not identified, although laboratory studies demonstrated growth of the coliform bacteria in lake water samples. Enterococci and E. coli were not observed to grow, however. Bacteria concentrations varied relatively little laterally across the lake, although strong vertical gradients in fecal coliform and enterococcus bacteria concentrations were present during summer stratification, with concentrations about 10x higher above the thermocline when compared with surface concentrations. In contrast, total bacteria, total virus and total coliform bacteria levels were unchanged with depth. Seasonal trends in bacteria concentrations were also present. This study shows that the choice of indicator bacteria and sampling depth can both strongly affect the apparent microbial water quality of a lake or reservoir.