Effects of Atmospheric Change and Agriculture on the Biogeochemistry and Microbial Ecology of Prairie Wetlands

Relatively little is known about the factors which regulate in water biogeochemical processes and food chains in prairie wetlands. Climatic warming, increased UV-radiation and agricultural activities will have interacting effects on these wetlands. We examined the effects of these processes on prairie wetland functioning and productivity with particular emphasis on production and cycling of organic carbon, especially dissolved organic carbon (DOC). Autotrophic and heterotrophic production are temperature dependent and temperature increases or decreases could affect production under more extreme climate change scenarios. DOC concentrations could decrease with increasing bacterial production and photolysis, leading to increases in UV-radiation penetration. This is pertinent to prairie wetlands because of their general shallowness. Considering the potential consequences of climatic warming, increased UV-radiation and agricultural activity on biogeochemistry and food chains, it is imperative that we obtain an understanding of the major rate processes in prairie wetlands and how these may be affected by external processes

Sub-inhibitory concentrations of different pharmaceutical products affect the meta-transcriptome of river biofilm communities cultivated in rotating annular reactors

Surface waters worldwide are contaminated by pharmaceutical products that are released into the environment from wastewater treatment plants. Here, we hypothesize that pharmaceutical products have effects on organisms as well as genes related to nutrient cycling in complex microbial communities. To test this hypothesis, biofilms were grown in reactors and subjected low concentrations of three antibiotics [erythromycin, ER, sulfamethoxazole, SL and sulfamethazine, SN) and a lipid regulator (gemfibrozil, GM). Total community RNA was extracted and sequenced together with PCR amplicons of the 16S rRNA gene using 454 pyrosequencing. Exposure to pharmaceutical products resulted in very little change in bacterial community composition at the phylum level based on 16S rRNA gene amplicons, even though some genera were significantly affected. In contrast, large shifts were observed in the active community composition based on taxonomic affiliations of mRNA sequences. Consequently, expression of gene categories related to N, P and C cycling were strongly affected by the presence of pharmaceutical products, with each treatment having specific effects. These results indicate that low pharmaceutical product concentrations rapidly provoke a variety of functional shifts in river bacterial communities. In the longer term these shifts in gene expression and microbial activity could lead to a disruption of important ecosystem processes like nutrient cycling.Peer reviewed: YesNRC publication: Ye

Metatranscriptomic Analysis of the Response of River Biofilms to Pharmaceutical Products, Using Anonymous DNA Microarrays ▿ †

Pharmaceutical products are released at low concentrations into aquatic environments following domestic wastewater treatment. Such low concentrations have been shown to induce transcriptional responses in microorganisms, which could have consequences on aquatic ecosystem dynamics. In order to test if these transcriptional responses could also be observed in complex river microbial communities, biofilm reactors were inoculated with water from two rivers of differing trophic statuses and subsequently treated with environmentally relevant doses (ng/liter to μg/liter range) of four pharmaceuticals (erythromycin [ER], gemfibrozil [GM], sulfamethazine [SN], and sulfamethoxazole [SL]). To monitor functional gene expression, we constructed a 9,600-feature anonymous DNA microarray platform onto which cDNA from the biofilms was hybridized. Pharmaceutical treatments induced both positive and negative transcriptional responses from biofilm microorganisms. For instance, ER induced the transcription of several stress, transcription, and replication genes, while GM, a lipid regulator, induced transcriptional responses from several genes involved in lipid metabolism. SN caused shifts in genes involved in energy production and conversion, and SL induced responses from a range of cell membrane and outer envelope genes, which in turn could affect biofilm formation. The results presented here demonstrate for the first time that low concentrations of small molecules can induce transcriptional changes in a complex microbial community. The relevance of these results also demonstrates the usefulness of anonymous DNA microarrays for large-scale metatranscriptomic studies of communities from differing aquatic ecosystems

Next-generation sequencing of microbial communities in the athabasca river and its tributaries in relation to oil sands mining activities

The Athabasca oil sands deposit is the largest reservoir of crude bitumen in the world. Recently, the soaring demand for oil and the availability of modern bitumen extraction technology have heightened exploitation of this reservoir and the potential unintended consequences of pollution in the Athabasca River. The main objective of the present study was to evaluate the potential impacts of oil sands mining on neighboring aquatic microbial community structure. Microbial communities were sampled from sediments in the Athabasca River and its tributaries as well as in oil sands tailings ponds. Bacterial and archaeal 16S rRNA genes were amplified and sequenced using next-generation sequencing technology (454 and Ion Torrent). Sediments were also analyzed for a variety of chemical and physical characteristics. Microbial communities in the fine tailings of the tailings ponds were strikingly distinct from those in the Athabasca River and tributary sediments. Microbial communities in sediments taken close to tailings ponds were more similar to those in the fine tailings of the tailings ponds than to the ones from sediments further away. Additionally, bacterial diversity was significantly lower in tailings pond sediments. Several taxonomic groups of Bacteria and Archaea showed significant correlations with the concentrations of different contaminants, highlighting their potential as bioindicators. We also extensively validated Ion Torrent sequencing in the context of environmental studies by comparing Ion Torrent and 454 data sets and by analyzing control samples. \ua9 2012, American Society for Microbiology.Peer reviewed: YesNRC publication: Ye

The attenuation of ultraviolet radiation in high dissolved organic carbon waters of wetlands and lakes on the northern Great Plains.

We used a scanning spectroradiometer to conduct underwater optical surveys of 44 waterbodies during the ice-free seasons of three consecutive years in wetlands and lakes in central Saskatchewan, Canada. The waterbodies ranged widely in dissolved organic carbon (DOC) concentration (4.1-156.2 mg L⁻¹) and conductivity (270-74,300 μohms cm⁻¹). Although penetration of UV radiation (UV-R; 280-400 nm) in these systems was largely a function of DOC concentration, as has been reported previously, UV-R penetrated more deeply in saline waterbodies than in freshwater systems with similar DOC concentrations. Power models representing our K dUV-B or KdUV-A versus DOC relationships were described by KdUV-B = 0.604DOC1.287 (r² = 0.76, N = 23) and KdUV-A = 0.428DOC1.136 (r² = 0.55, N = 24) for freshwater systems and KdUV-B = 2.207DOC0.732 (r² = 0.40, N = 20) and KdUV-A = 1.436DOC0.600(r² = 0.18, N = 20) for saline systems. Our data, when combined with data from other researchers, resulted in the more general freshwater models KdUV-B = 0.705DOC1.248 (r² = 0.84, N = 43) and KdUV-A = 0.470DOC1.112 (r² = 0.70, N = 44), UV-B radiation (280-320 nm) is not expected to penetrate deeply (typically <50 cm) in prairie lakes and wetlands because of high intrinsic DOC concentrations. However, the central plains are characteristically windy and this, coupled with the shallowness of many of these systems, suggests that biota may still be at risk from present-day and future-enhanced levels of UV-B (which may result from ozone depletion). Moreover, this risk may be exacerbated in saline systems. This could be significant, especially because saline waterbodies are often highly productive and represent important North American staging areas for shorebirds and waterfowl

Model fits describing N effect on mesocosm plankton dynamics.

<p>Least squares regression analysis (<i>n</i> = 15) of phytoplankton and bacterial abundance and production (y) as functions of urea load (x). Models were selected using Akaike information criterion corrected for small sample sizes (AIC_c), and ranked based on AIC_c score, with best-fitting models in bold. Models with no explanatory power (i.e. r² = 0) are omitted. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188652#pone.0188652.g002" target="_blank">Fig 2</a> for graphical representation of best-fit models.</p

Effects of urea fertilization rate (mg N L^-1 week^-1) on mean planktonic parameters.

<p>Results averaged for days 7–21. Response variables include (a) phytoplankton biomass (as Chl <i>a</i>), (b) bacterial density, (c) gross primary production (GPP), (d) bacterial C consumption (BCC; productivity + respiration), (e) the approximate metabolic balance of plankton communities, measured as GPP: BCC, and (f) dissolved oxygen concentration (DO). Data in each panel includes July (black circles and thick black lines), August (grey triangles and grey lines), and September (white squares and thin black lines) experiments. Solid lines indicate best-fit regression models detailed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188652#pone.0188652.t001" target="_blank">Table 1</a>, dashed lines indicate direction of change for trial in which statistically-significant regression models could not be fit. Error bars = ± 1 S.E, and <i>n</i> = 9.</p

Seasonal limnological trends in Wascana Lake, Saskatchewan May–August 2009.

<p>(a) total dissolved (TDP) and soluble reactive phosphorus (SRP) concentrations, (b) total dissolved nitrogen (TDN) concentration and phytoplankton biomass (as Chl <i>a</i>), and (c) final concentrations of Chl <i>a</i> (fertilized treatment minus control) after 72-h bottle bioassay incubations of Wascana Lake water receiving growth-saturating concentrations of NH₄ (N), PO₄^3- (P), or both N and P (N+P). Analysis of variance with Tukey’s post hoc tests identified statistically significant (asterisk) phytoplankton biomass response (<i>p</i> < 0.05) relative to control bottles. Vertical dashed grey lines show the start dates of the monthly mesocosm experiments.</p