Phylogenetic shifts of bacterioplankton community composition along the Pearl Estuary: the potential impact of hypoxia and nutrients

Abstract

The significance of salinity in shaping bacterial communities dwelling in estuarine areas has been well documented. However, the influences of other environmental factors such as dissolved oxygen and nutrients in determining distribution patterns of both individual taxa and bacterial communities inhabited local estuarine regions remain elusive. Here, bacterioplankton community structures of surface and bottom waters from eight sites along the Pearl Estuary were characterized with 16S rRNA gene pyrosequencing. The results showed significant differences of bacterioplankton community between freshwater and saltwater sites, and further between surface and bottom waters of saltwater sites. Synechococcus dominated the surface water of saltwater sites while Oceanospirillales, SAR11 and SAR406 were prevalent in the bottom water. Betaproteobacteria was abundant in freshwater sites, with no significant difference between water layers. Occurrence of phylogenetic shifts in taxa affiliated to the same clade was also detected. Dissolved oxygen explained most of the bacterial community variation in the redundancy analysis targeting only freshwater sites, whereas nutrients and salinity explained most of the variation across all samples in the Pearl Estuary. Methylophilales (mainly PE2 clade) was positively correlated to dissolved oxygen, whereas Rhodocyclales (mainly R.12up clade) was negatively correlated. Moreover, high nutrient inputs to the freshwater area of the Pearl Estuary have shifted the bacterial communities toward copiotrophic groups, such as Sphingomonadales. The present study demonstrated that the overall nutrients and freshwater hypoxia play important roles in determining bacterioplankton compositions and provided insights into the potential ecological roles of specific taxa in estuarine environments.

Prokaryotic Community Structure Driven by Salinity and Ionic Concentrations in Plateau Lakes of the Tibetan Plateau

“…4; see also Table S5 in the supplemental material). In agreement with our findings, many previous studies have shown that pH and the DO concentration are major drivers of microbial community distributions in various ecosystems (22,(81)(82)(83)(84)(85)(86). pH has been described to be a master variable that integrates the physiochemical status of aquatic ecosystems (87).…”

“…In a study of the bacterioplankton community composition, the relative importance of the NH 4 ϩ , PO 4 3Ϫ , NO 3 Ϫ , and DO concentrations differed at the order level versus the genus level (22). Similarly, Mantel tests revealed that correlations between the prokaryotic community composition and certain parameters (HCO 3 Ϫ and Na ϩ concentrations, temperature, pH) differed at the genus (95%), species (97%), and subspecies (99%) levels (91).…”

“…Salinity is a dominant environmental selective force governing prokaryotic communities in aquatic systems, such as natural inland lakes (8,11,12), solar saltern ponds (9,24,25), estuaries (19,21,22), and the Baltic Sea (10). Research conducted worldwide found that salinity, rather than extremes of temperature, pH, or other physical and chemical factors, is the major environmental determinant of the microbial community composition (30).…”

“…A better understanding of the taxonomic composition and diversity of microbial communities in saline lakes and the mechanisms that govern the community structure is a long-standing goal and challenge for microbial community ecologists (15)(16)(17). Many previous studies have addressed the effect of salinity on microbial community composition and diversity; however, such studies have generally been limited to the salinity gradients of dynamic estuaries (18)(19)(20)(21)(22), solar saltern ponds (4,7,9,(23)(24)(25), and the vertical water columns or sediments of salt lakes (26)(27)(28). Only three studies, based on limited numbers of water samples, have focused on natural inland lakes (8,11,12).…”

Temporal and Vertical Variation in Microbial Community Composition in Response to Physicochemical Characteristics in a Water Column of Highly Eutrophied Jinhae Bay, South Korea

“…In the northern Gulf of Mexico, one of the largest eutrophication-driven hypoxic zones in the world [Diaz, 2001], it is reported that variation in bacterial communities is associated with chemical differences between oxic and hypoxic water conditions [Bristow et al, 2015;Devereux et al, 2015]. Liu et al [2015] also reported that nutrients and bottom water hypoxia significantly affect changes in bacterioplankton communities in the Pearl Estuary.…”