Abstract
The objective of the present study was to investigate the influence of environmental conditions on the bacterial community composition water, sediment and riparian soil during different water flow periods. For this purpose, samples of three habitats (water, sediment and riparian soil) were collected from five polluted sites and one reference site along the Suquia River during high and low water flow periods. The pH, dissolved oxygen, conductivity and water temperature were measured in situ, with total organic carbon content, nitrate and ammonia concentration being evaluated for all samples. In addition, pH, conductivity and total N were determined the sediment and riparian soil samples, and the bacterial community composition of water, sediments and riparian soil samples was monitored using restriction fragment length polymorphism of the 16S rRNA gene. The results showed that the bacterial community composition of water was different from that of sediments or riparian soil. A redundancy analysis indicated that the changes the bacterial community composition the Suquia River were primarily correlated with variations dissolved oxygen, conductivity and pH. The water bacterial community composition was very variable among sites and water flow periods, while that of sediments differed according to the water flow period, which was associated with temperature variation. Lastly, riparian soil, differences were found the bacterial community composition of the sites located before and after Cordoba city. Our findings suggest distinct distribution patterns the bacterial community compositions of the three habitats evaluated.
Highlights
Rivers play a role in both human life and ecological balance
The results show that: a) the bacterial community composition (BCC) of water was different from that of the sediments or riparian soil, which were found to be more similar, and b) the BCC in water was more variable whereas that of soil or sediments was more stable
Other studies performed on diverse aquatic ecosystems detected bacterial community differences between sediment and water (Dillon et al 2009; Staley et al 2015; Ibekwe et al 2016; Wei et al 2016), but as few studies examined BCC in riparian soil in aquatic ecosystems, it is difficult to compare our results with these investigations
Summary
Rivers play a role in both human life and ecological balance. As well as being used in transportation and as a drinking water source for humans, they form the main link between terrestrial and aquatic habitats as part of the hydrological and nutrient cycles (Wetzel 2001; Barton and Northup 2011; Tiquia 2011). Other authors have reported bacterial community shifts in relation to environmental variables in aquatic ecosystems (Powell et al 2003; Judd et al 2006; Bissett et al 2007; Ikenaga et al 2010; Fujii et al 2012; Arroyo et al 2015). Seasonal shifts in water column stability and water temperature can lead to an annual pattern of bacterial community variability (Kirchman et al 2005; Ibekwe et al 2012), with Yachi and Loreau (1999) affirming that microbial diversity has an important role in buffering environmental variability and in maintaining the ecosystem process. Higher diversity increases the probability that the species of a community respond in differential ways to environmental stress
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