Lagoon Wastewater Effluent Impacts Stream Metabolism in Red River Tributaries

Lagoons are the most common form of sewage treatment for rural Canadian communities and may therefore be a major source of pollution to local waterways. However, the environmental effects of pulse releases of lagoon effluent are largely unknown. This study reports on changes in physicochemical conditions and stream metabolism occurring as result of summer lagoon effluent releases into Red River tributaries, Manitoba, Canada. We calculated metrics of stream metabolism using the single-station, open water method. We found that an effluent release results in a significant short-term increase in physicochemical (i.e., water nutrients, stream discharge) conditions which had a subsidy effect on stream metabolism. We also found that stream metabolism was significantly greater in effluent exposed versus unexposed reaches; however, our results suggest the degree of effect depends on whether the release occurred early or late in the summer. The findings of this study have implications for lagoon management and future stream monitoring projects aimed at evaluating the effects of lagoon wastewater effluent

Factors affecting ammonium uptake in streams - an inter-biome perspective

The Lotic Intersite Nitrogen experiment (LINX) was a coordinated study of the relationships between North American biomes and factors governing ammonium uptake in streams. Our objective was to relate inter-biome variability of ammonium uptake to physical, chemical and biological processes. 2. Data were collected from 11 streams ranging from arctic to tropical and from desert to rainforest. Measurements at each site included physical, hydraulic and chemical characteristics, biological parameters, whole-stream metabolism and ammonium uptake. Ammonium uptake was measured by injection of \u275~-ammonium and downstream measurements of 15N-ammonium concentration. 3. We found no general, statistically significant relationships that explained the variability in ammonium uptake among sites. However, this approach does not account for the multiple mechanisms of ammonium uptake in streams. When we estimated biological demand for inorganic nitrogen based on our measurements of in-stream metabolism, we found good correspondence between calculated nitrogen demand and measured assimilative nitrogen uptake. 4. Nitrogen uptake varied little among sites, reflecting metabolic compensation in streams in a variety of distinctly different biomes (autotrophic production is high where allochthonous inputs are relatively low and vice versa). 5. Both autotrophic and heterotrophic metabolism require nitrogen and these biotic processes dominate inorganic nitrogen retention in streams. Factors that affect the relative balance of autotrophic and heterotrophic metabolism indirectly control inorganic nitrogen uptake

Whole-stream metabolism: strategies for measuring and modeling diel trends of dissolved oxygen

Stream metabolism is used to characterize the allochthonous and autochthonous basis of stream foodweb production. The metabolic rates of respiration and gross primary production often are estimated from changes in dissolved O2 concentration in the stream over time. An upstream–downstream O2 accounting method (2-station) is used commonly to estimate metabolic rates in a defined length of stream channel. Various approaches to measuring and analyzing diel O2 trends have been used, but a detailed comparison of different approaches (e.g., required reach length, method of measuring aeration rate [k], and use of temperature-corrected metabolic rates) is needed. We measured O2 upstream and downstream of various reaches in Kings Creek, Kansas. We found that 20 m was the approximate minimum reach length required to detect a significant change in O2, a result that matched the prediction of a calculation method to determine minimum reach length. We assessed the ability of models based on 2-station diel O2 data and k measurements in various streams around Manhattan, Kansas, to predict k accurately, and we tested the importance of accounting for temperature effects on metabolic rates. We measured gas exchange directly with an inert gas and used a tracer dye to account for dilution and to measure velocity and discharge. Modeled k was significantly correlated with measured k (Kendall's τ, p < 0.001; regression adjusted R²  =  0.70), but 19 published equations for estimating k generally provided poor estimates of measured k (only 6 of 19 equations were significantly correlated). Temperature correction of metabolic rates allowed us to account for increases in nighttime O2, and temperature-corrected metabolic rates fit the data somewhat better than uncorrected estimates. Use of temperature-correction estimates could facilitate cross-site comparisons of metabolism

Functions of Ecosystems: Stream Metabolism as an efficient and effective means to gage the health and understand the interworking of urban streams in a watershed of Rock Island, IL

Stream metabolism is a critical functional measure of stream health that integrates physical parameters like slope and discharge, with ecosystem functions like photosynthesis and respiration. Stream metabolism is widely studied; however, urban stream metabolism remains poorly understood. Stream metabolism was measured for five streams ranging from 1st to 5th orders from October 11th to October 18th 2017 and four streams ranging from 1st to 4th order from October 22nd to 25th 2017 located within an approximately 9.3 square kilometer watershed of Rock Island, IL that has an urban to suburban type of development. These measurements were carried out using calibrated HACH water quality multiprobes measuring continuous temperature and oxygen concentrations over five days for the earlier data collection and three days for the later data collection at thirty-minute intervals. Metabolism was estimated using a Monte Carlo Markov Chain approach that took into account irradiance and gas-transfer velocity to estimate the 24 hr average and time stepped community respiration, gross primary production, and the total mass flux of O2 by gas exchange. This data was then compared with previously collected physical and chemical data from each site. All sites were characterized by relatively low rates of gross primary production that were far less than community respiration, a pattern that indicates a reliance on energy input from outside the stream rather than in stream photosynthesis. Variation in respiration and photosynthesis were poorly explained by the existing water quality data for the sites (range of R2 data). However, two of the sites experienced transient drops in dissolved oxygen to at or near 0 mg/l. When those two sites are removed from the analysis, total Phosphate concentration (mg/l) and fecal coliform where both negatively related to integrated community respiration (R2 value of .4965 and .53 respectively). These transient drops in oxygen remain unexplained but show the importance of continuous monitoring for capturing potentially critical ecosystem events

Assessment of Stream Metabolism and Associated Environmental Drivers in the Greiner Lake Watershed, Nunavut, Canada

Stream metabolism is an ecological process that can be monitored to assess carbon cycling and productivity within a stream ecosystem. GPP (gross primary productivity) is measured as oxygen produced by autotrophs and ER (ecosystem respiration), which is measured by oxygen depleted by all living organisms. Complications arise when estimating GPP and ER in the Arctic because most methods require a period of darkness when GPP ceases, however, summer regimes of photosynthetically active radiation (PAR) do not reach zero. Furthermore, natural diffusion of oxygen from the atmosphere (k) must be accounted for but this requires extensive field work, thus posing problems for remote locations. Few studies have assessed how stream metabolism is influenced by the surrounding environment, even though it is well established that stream metabolism in other biomes is affected by key environmental variables. The thesis assesses methods that are appropriate for estimating stream metabolism in the Arctic and determines stream metabolism and associated environmental variables in the Greiner Lake Watershed, Nunavut. Stream metabolism was estimated using streamMetabolizer and empirical methods. These methods were compared based on values expected for low productivity streams, and model diagnostics (process and observation error) for Bayesian statistics. StreamMetabolizer produced biologically possible days with realistic average values and ranges of GPP and ER. Estimates of GPP and ER from streamMetabolizer were used in a partial least square regression analysis (PLSR) with environmental variables measured at each site (water chemistry, channel form, land cover type and surrounding waterbodies). I discovered that GPP was positively related to median substrate particle size (D50), and ER was positively related to the area of upstream lakes and stream width. D50 may have been providing ideal habitats for primary producers, and lakes may have been impacting downstream controls of ER. Overall, streamMetabolizer is a useful method for determining stream metabolism in Arctic environments that are remote and have limited periods of darkness in the summer. Moreover, this research contributes to a growing database of stream metabolism in the Arctic and indicates key environmental variables influencing stream metabolism in the Arctic

Effects of wastewater treatment plant pollution on in-stream ecosystems functions in an agricultural watershed

We studied the effect of point-source and non-point-source pollution on the retention capacity of the stream and its link with the metabolic state (primary production and respiration) and invertebrates assemblages in a third order Mediterranean stream. Two experimental sites were chosen: one in the upper part of the catchment (Monte´gut site) characterized by low concentrations in nitrate and phosphate and one in the lower part of the catchment (Le´zat site) characterized by high nitrate and phosphorus concentrations. Both experimental sites were located on reaches that included a Waste Water Treatment Plant (WWTP) point nutrient source allowing discussion of the relative effects of point-source and non-point-source nutrients loads on ecosystem function (respiration and uptake rates) and aquatic organism assemblages. NH4 +-N, and PO43x-P uptake rates were determined using solute additions conducted at constant rates (short-term nutrient addition procedure) and NO3 x-N uptake rates were determined using instantaneous solute addition (slug addition procedure). Rates of gross primary production (GPP) and ecosystem respiration were determined using the open system, two-stations diurnal oxygen change method. Benthic invertebrate communities were investigated for species and functional feeding groups diversities measurements. Results show that autotrophy in the river results from nutrients of two distinct origins: point sources for phosphorus (urban area and WWTP) and non-point sources for nitrogen (agricultural zones) with local additions from WWTP inputs. Comparison between the two sites shows that the WWTP did not affect uptake rates, respiration or primary production of the ecosystem in the low-nutrient Monte´gut reach despite increase of invertebrates communities biomass density. Inputs from the WWTP, in the high nitrate and phosphate Le´zat reach, increased respiration, lower benthic biomass and led to changes in the species composition and did not affect uptake rates

Modeling the coupled dynamics of stream metabolism and microbial biomass

Estimating and interpreting ecosystem metabolism remains an important challenge in stream ecology. Here, we propose a novel approach to model, estimate, and predict multiseasonal patterns of stream metabolism (gross primary production [GPP] and ecosystem respiration [ER]) at the reach scale leveraging on increasingly available long-term, high-frequency measurements of dissolved oxygen (DO). The model uses DO measurements to estimate the parameters of a simple ecosystem model describing the underlying dynamics of stream autotrophic and heterotrophic microbial biomass. The model has been applied to four reaches within the Ybbs river network, Austria. Even if microbial biomasses are not observed, that is, they are treated as latent variables, results show that by accounting for the temporal dynamics of biomass, the model reproduces variability in metabolic fluxes that is not explained by fluctuations of light, temperature, and resources. The model is particularly data-demanding: to estimate the 11 parameters used in this formulation, it requires sufficiently long, for example, annual, time series, and significant scouring events. On the other hand, the approach has the potential to separate ER into its autotrophic and heterotrophic components, estimate a richer set of ecosystem carbon fluxes (i.e., carbon uptake, loss, and scouring), extrapolate metabolism estimates for periods when DO measurements are unavailable, and predict how ecosystem metabolism would respond to variations of the driving forces. The model is seen as a building block to develop tools to fully appreciate multiseasonal patterns of metabolic activity in river networks and to provide reliable estimations of carbon fluxes from land to ocean