Alternative states drive the patterns in the bacterioplankton composition in shallow Pampean lakes (Argentina)

Abstract

We assessed the influence of environmental factors in shaping the free-living bacterial community structure in a set of shallow lakes characterized by contrasting stable state patterns (clear-vegetated, inorganic-turbid and phytoplankton-turbid). Six temperate shallow lakes from the Pampa Plain (Argentina) were sampled over an annual cycle, and two fingerprinting techniques were applied: a 16S rDNA analysis was performed using denaturing gradient gel electrophoresis (DGGE) profiles, and a 16S-23S internally transcribed spacer region analysis was conducted by means of automated ribosomal intergenic spacer analysis (ARISA) profiles. Our results show that the steady state that characterized the different shallow lakes played a major role in structuring the community: the composition of free-living bacteria differed significantly between clear-vegetated, inorganic-turbid and phytoplankton-turbid shallow lakes. The state of the system was more important in determining these patterns than seasonality, geographical location or degree of hydrological connectivity. Moreover, this strong environmental control was particularly evident in the pattern observed in one of the lakes, which shifted from a clear to a turbid state over the course of the study. This lake showed a directional selection of species from a typical clear-like to a turbid-like community. The combined DGGE/ARISA approach revealed not only broad patterns among different alternative steady states, but also more subtle differences within different regimes.

Multi-Elements in Waters and Sediments of Shallow Lakes: Relationships with Water, Sediment, and Watershed Characteristics

“…Some research has explored how nutrients in lakes relate to nearby land use (Fraterrigo and Downing 2008; Wezel et al 2013) and phytoplankton biomass (Grace et al 2010; Borics et al 2013). Related studies of shallow lakes have focused on identifying factors responsible for water-clarity regime shifts, variations in phytoplankton biomass, and macrophyte abundance (Schippers et al 2006; Zimmer et al 2009; Bayley et al 2013; Brothers et al 2013; Llames et al 2013; Zhang et al 2013; Robin et al 2014). As mentioned previously, our study adds to these earlier works by examining concentrations of multiple elements, including the rare earth elements in the waters and sediments of shallow lakes.…”

“…We hypothesized that land use within watersheds, along with water and sediment characteristics, influenced element concentrations in waters and sediments of shallow lakes. Earlier shallow lake studies focused on regime shifts, carbon, phosphorus and nitrogen cycling, phytoplankton biomass, and macrophyte abundance (Scheffer and Jeppesen 1998; Hansel-Welch et al 2003; Schippers et al 2006; Bayley et al 2007, 2013; Zimmer et al 2009; Brothers et al 2013; Llames et al 2013; Zhang et al 2013; Robin et al 2014). Most of these earlier works focused on influences of various environmental variables on water quality and chemistry, but few have considered physical or chemical aspects of shallow lake sediments (Barko and James 1998; Sahuquillo et al 2012; Kissoon et al 2013; Wu et al 2014).…”

Phenotypic plasticity in freshwater picocyanobacteria

“…Genomic DNA from filters was extracted using a CTAB protocol (Fernandez Zenoff et al ., ), as described in Llames et al . ().…”

“…The 16S rRNA gene fragments were amplified with specific cyanobacterial primers CYA359F (CG) and CYA781R (a) (Supporting Information Table S2) using the PCR protocol described in Llames et al . (). The PCR products obtained (∼500 pb) were analysed on a 40‐65% denaturant DGGE gel (see details in Supporting Information material).…”

Diversity of photosynthetic picoeukaryotes in eutrophic shallow lakes as assessed by combining flow cytometry cell-sorting and high throughput sequencing

“…Samples were then incubated at 56°C for 30 min and proteinase K inactivated at 75°C for 10 min. After, the protocol follows as described in Llames et al (2013). For filtered total plankton sample (FTP) DNA extraction was performed using the CTAB protocol (Fernández Zenoff, Siñeriz and Farías 2006).…”