Coldwater Streams Research Articles

Forested Streams May Warm More Than Observations Predict

Understanding how temperatures of cold-water streams respond to global warming could help clarify the impacts of climate change on aquatic ecosystems.

Experimental parametric study of membrane distillation unit using solar energy

Solar distillation is a promising method for the supply of freshwater to rural communities because water is a vital factor for the survival of humans. Therefore potable water demand is increasing continuously because of the industrial, population and, fast agricultural applications. Nowadays, different techniques for water purification have been created to provide freshwater from salty and polluted water such as solar distillation method to distill brackish/saline water. This work presents an experimental study of the solar membrane distillation unit which is coupled with direct contact membrane (DCMD) which located at Kairouan University. The system is installed as part of a cooperation project research and development between Tunisian Electromechanical Systems Laboratory and German Institute for Solar Energy Systems entitled: Solar driven membrane distillation for resource efficient desalination in remote areas. For the heating of the hot feed water stream, a heat exchanger is included which can be operated with any external heat supply between 60 and 80 °C. For the cooling of the cold feed water stream, no heat exchanger is included. The cooling can be provided over the intake of cold feed water. The effect of solar irradiation and all temperature on the journal productivity of the unit has been presented.

Developing precipitation- and groundwater-corrected stream temperature models to improve brook charr management amid climate change

Conserving coldwater stream ecosystems in a warming world requires understanding how water temperature changes will affect the sustainability of coldwater fish populations such as brook charr (Salvelinus fontinalis). To date, many models for predicting stream temperature have either assumed spatially uniform (inaccurate) air-stream temperature relationships or required expensive measurement of hydrometeorological drivers (e.g., solar radiation, convection) in a manner impractical for fisheries management. Hence, we developed an accurate, cost-effective, management-relevant modeling approach for projecting how changes in air temperature, precipitation, and groundwater inputs will affect coldwater stream temperatures and brook charr survival and growth in Michigan, USA. Precipitation- and groundwater-corrected models predicted stream temperatures more accurately than air-stream temperature models. Projected stream warming intensified in proportion to simulated air temperature warming and was most extreme in surface runoff-dominated streams with limited groundwater-driven thermal buffering. However, groundwater-dominated streams will not invariably provide sufficient coldwater habitats for brook charr survival and growth if groundwater temperatures increase or groundwater inputs decline due to reduced precipitation. Amid resource limitations, fisheries managers can use the stream temperature modeling approach described herein to predict effects of climate change on brook charr survival and growth and take actions to facilitate their sustainability in riverine systems.

A new fish based multi-metric assessment index for cold-water streams of the southern Caspian Sea Basin in Iran

Numerous riverine ecosystems in Iran are currently suffering due to various human activities, which are directly affecting the physico-chemical conditions of running waters and influencing the aquatic biota. In this study, we chose the cold-water streams of the Southern Caspian Sea Basin in Iran to analyse human pressures and develop a multi-metric fish index for the cold-water streams dominated by brown trout, Salmo trutta in this Basin. To do this, the fish and environmental data were sampled in 67 medium sized streams in the Caspian Mountains. In total, nine fish metrics were calculated. Moreover, 27 criteria describing major anthropogenic pressures for the entire sampling area were used to generate a regional pressure index that accounted for potential effects of multiple human pressures. For the index development, we first defined reference sites and then quantified differences of fish metrics between the reference and impacted sites. The multiple linear regressions were used for describing metric responses to natural environmental differences in the absence of any human pressures. Finally, by testing the ability of each metric for discrimination of impacted and reference sites as well as their sensitivity to a gradient of regional pressure index, the metrics density of brown trout and biomass of sub-adult brown trout explained human pressures best. Our multi-metric fish index performed well in discriminating between reference and impacted sites, giving a significant negative linear response to a gradient of regional pressure index. In general, the development of such an index offers an opportunity to enhance national bio-monitoring programmes in Iran.

A Long‐Term Analysis of Channel Morphology and Stream Substrates before and after Sediment Trap Construction in Michigan Trout Streams

AbstractSediment traps are commonly used to remove excess sand bedload from coldwater streams and to improve channel morphology and substrate conditions for salmonids in the Midwestern United States. However, few scientific evaluations of the rate and spatial extent of channel changes associated with sediment trapping efforts have occurred. We used a series of stream channel morphology measurements taken over a 10‐year period in five Michigan streams to show that excavation of sediment traps had only small effects on mean channel bank‐full depth, bank‐full cross‐sectional area, and bank‐full width as well as substrate composition in the streams studied. When they did occur, changes in each of these metrics occurred both upstream and downstream of—and often in close proximity to—the sediment traps. While few positive effects of sediment traps were noted, there were also no negative effects to report. The construction of sediment traps did not lead to broad‐scale widening of stream channels, and no excessive channel incision was observed in any of the study streams. Thus, concerns about typical sediment trap operations upsetting the stream‐sediment equilibrium and creating excessive down‐cutting appear to be unfounded for Michigan's low‐gradient, naturally sandy stream channels. We conclude that sediment traps are unlikely to have any large‐scale channel morphology or substrate effects that would be beneficial to stream salmonids when used as a stand‐alone habitat treatment.

Dynamic Modelling and Control of Thermal Energy Storage

Thermal energy storage (TES) is a critical element in district heating systems and having a good understanding of its dynamic behaviour is necessary for effective energy management. TES supports heat sources in achieving a steady power supply. Achieving heat and electric load demand translates into a discharging and charging control problem in terms of stored heat energy. To this end, an accurate dynamic model is essential to design effective controllers to improve district heating performance. A thermal dynamic model of a water tank, together with controllers for energy charging and discharging processes, are presented in this paper. The model is based on a computational fluid dynamics approach. It is developed using thermal stratification. The hot or cold-water stream which vertically crosses each tank section is considered to describe heat transfer. This is a non-linear process represented by partial differential equations, which are linearised to obtain a suitable model for control system design. State-space and transfer function representations of the system are obtained. The non-linear model is implemented in MATLAB/Simulink to design a linear controller that regulates the mass flow rate of cold and hot water to fill or empty the tank’s energy according to performance specifications. The design of regulation and tracking controllers is explained. Simulation results show that a good performance in terms of the mass flow rate input demands is achieved with the proposed controllers.

Propagation of Eastern Hellbenders Cryptobranchus alleganiensis alleganiensis in a Recirculating Aquaculture System at Shepherd of the Hills State Fish Hatchery

AbstractThe hellbender Cryptobranchus alleganiensis is an endangered aquatic salamander inhabiting coldwater streams within the Ozark Highlands of Missouri. Over the past few decades, there has been a severe decline in the populations of the two subspecies of hellbender in this region—the Eastern hellbender C. a. alleganiensis and the Ozark hellbender C. a. bishopi—accompanied by little to no recruitment of young age‐classes; projections now call for negative long‐term population growth for both subspecies. Captive propagation is thus considered essential for the long‐term recovery of this species in Missouri, along with addressing the causes for its decline in the wild. Since 2007, Shepherd of the Hills Fish Hatchery has been the primary rearing facility in Missouri for the early life stages of Eastern hellbenders. This facility has focused on hatching fertilized eggs collected from the wild and rearing animals for repatriation into their natal streams. This paper describes the recirculating aquaculture system used to rear Eastern hellbenders, the culture techniques that have been developed, and some of the results.

A Review of Beaver–Salmonid Relationships and History of Management Actions in the Western Great Lakes (USA) Region

AbstractWithin the western Great Lakes (WGL) region of the USA (Michigan, Minnesota, and Wisconsin), the ecological impact that the North American beaver Castor canadensis (hereafter, “beaver”) has on coldwater streams is generally considered to negatively affect salmonid populations where the two taxa interact. Beavers are common and widespread within the WGL region, while coldwater streams that support salmonid populations are scarcer landscape features; as such, all three states currently prioritize the habitat needs of salmonids in portions of each state by conducting beaver control in coldwater tributaries. In this paper, we review the history of beaver–salmonid interactions within the WGL region, describe how this relationship and management actions have evolved over the past century, and review all published studies from the region that have evaluated beaver–salmonid interactions. Our review suggests that beavers’ impact varies spatially and temporally depending on a variety of local ecological characteristics (e.g., stream gradient and prevalence of groundwater inputs). We found that beaver activity is often deleterious to salmonids in low‐gradient stream basins but is generally beneficial in high‐gradient basins and that ample groundwater inputs can offset the potential negative effects of beavers by stabilizing the hydrologic and thermal regimes within streams. However, there was an obvious lack of empirical data and/or experimental controls within the reviewed studies, which we suggest emphasizes the need for more data‐driven beaver–salmonid research in the WGL region. Resource managers are routinely faced with an ecological dilemma between maintaining natural environmental processes within coldwater ecosystems and conducting beaver control for the benefit of salmonids; this dilemma is further complicated when the salmonids in question belong to nonnative species. We anticipate that future beaver–salmonid research will lead to a greater understanding of this ecologically complex relationship, allowing managers to be better informed of when and where beaver control is necessary to achieve the desired management objectives.

Sheathia jinchengensis (Batrachospermales, Rhodophyta), a new freshwater red algal species described from North China

A new species of freshwater red algae, Sheathia jinchengensis, is described based on material collected from rocks in a clean and cold-water stream from the Jincheng region of Shanxi province in North China. Molecular sequences of rbcL and psbA genes were used to evaluate the phylogenetic relationship among samples of S. jinchengensis and other Sheathia species from several regions of the world. The results showed that S. jinchengensis formed an independent branch and separated from the previously published sequence data of other Sheathia taxa. From a morphological point of view, this new species differs also from other species of the genus by the smaller diameter of whorls (167.0–312.5 μm) and larger carpogonium diameter (17.0–29.0 μm). Comparison of sequence variation and thallus morphology with other Sheathia taxa resulted in the proposal of the new species—S. jinchengensis. Additionally, two endemic Batrachospermum species described earlier from China i.e., B. hongdongense and B. longipedicellata are now transferred to the genus Sheathia based on the present study as S. hongdongensis (S.L.Xie & J.Feng) Han, Nan, Feng, Lv, Liu, Kociolek et Xie comb. nov. and S. longipedicellata (Hua & Shi) Han, Nan, Feng, Lv, Liu, Kociolek et Xie comb. nov.

Effects of Introduced Small Wood in a Degraded Stream on Fish Community and Functional Diversity

Though the effects of introduced wood on fishes is widely studied for salmonids in upland coldwater streams, there are few studies on this topic conducted in the Coastal Plain of the southeastern US. This research gap is problematic because the introduction of wood is a critical component of efforts aimed at conserving the threatened fish diversity of the Coastal Plain, but managers lack data on the effects of installed wood on fish communities. Over a nearly 4-year study period, we contrasted the effects of introduced, small, wood bundles on the fish community in a channelized and deeply incised sand-bed Coastal Plain stream with an unmanipulated reference treatment. The central question was whether or not stream reaches with introduced wood had greater taxonomic and functional diversity than unmanipulated reference reaches within the same stream. The introduction of modest amounts of small wood had measurable and biologically significant positive impacts on fish community composition and perhaps functional diversity relative to stream reaches lacking wood. However, species-specific responses varied among treatments, suggesting the design of wood installations has an impact on whether or not managemen t goals are achieved.

Heat Pump for Energy-Efficient Sugarcane Juice Freeze Pre-concentration

A freeze concentration system with two-stage heat pump was investigated for pre-concentrating sugarcane juice in a jaggery making process. Two identical vented double-wall tube-and-tube heat exchangers were used as latent heat exchangers. One latent heat exchanger was operated as an evaporator, which selectively froze water from the juice. Another latent heat exchanger was operated as a condenser, which melted ice formed in a previous half cycle. Excess condenser duty, as a result of compressor work input and heat leakage into the cold sections of the system, was rejected with the help of second-stage compressor and concentrated juice and water heater. High juice velocity in the tube-and-tube heat exchanger helped to reduce inclusion in layer freezing. Raw juice was pre-cooled in a three fluid heat exchanger using concentrated juice and cold water streams from the latent heat exchangers. Pre-concentration of sugarcane juice from 20 to 40 °Brix helped to save about 63% of bagasse. Heat removed during freezing was one-seventh of that required for evaporation. R290 was found the best option amongst refrigerants R744 (CO2), R290 (C3H8) and R22 (CHClF2). Performance of system was evaluated considering the effect of thermal mass, ambient heat gain, variation in freezing point depression and ice layer thickness. Cooling COP of 14 can be achieved in a practicable system with evaporation at − 8 °C, condensation at 3 °C and the excess heat rejection at 34 °C. This shows that specific energy consumption can be as low as 8.8 kWhe/m3 of separated water.

Biological Responses in Brook Trout (Salvelinus fontinalis) Caged Downstream from Municipal Wastewater Treatment Plants in the Credit River, ON, Canada.

To determine whether discharges of contaminants from municipal wastewater treatment plants (WWTPs) may be contributing to the decline in populations of brook trout (Salvelinus fontinalis) in the watershed of the Credit River in ON, Canada, we caged juvenile brook trout upstream and downstream of the WWTPs of the small communities of Acton and Orangeville. Levels of vitellogenin were significantly elevated in liver tissue of trout caged downstream of both WWTPs, indicating exposure to estrogenic substances. Levels of thiobarbituric acid reactive substances indicative of oxidation of lipids were elevated in the gill tissue of brook trout caged downstream of the Orangeville WWTP, and levels of total glutathione were significantly lower in the gills of brook trout caged downstream of the Acton WWTP. Both biomarkers are indicative of oxidative stress, although many constituents of wastewater could be responsible for these responses. More work is needed to determine whether discharges of wastewater are contributing to the decline of brook trout in the Credit River and other cold-water streams in the Lake Ontario catchment basin.

In Brook Trout, Sometimes the Risk Is Worth the Reward

Coldwater streams flow through the Appalachian Mountains, giving life to one of the region's most valuable social and economic resources: Brook Trout Salvelinus fontinalis. The vitality of this ico...

Numerical analysis on the advantage of using PCM heat exchanger in liquid-flow window

Liquid-flow window is a multi-glazing system with a flowing liquid layer in the window cavity. Thermal transmission is largely restricted and warm water can be produced. These lead to considerable energy saving in buildings with daytime hot water demand. For service extension, it is necessary to enhance the thermal storage capability of the system as solar energy is an intermittent heat source. In this study, the potential advantage of applying PCM onto the double-pipe heat exchanger of liquid flow window was evaluated for different situations, including the unfavorable case with night-time hot water demand. The enthalpy-based method was adopted for precise modelling of the heat transfer process in the PCM layer. The validity of the numerical model was confirmed by experimental comparison with published data. Numerical studies were then conducted based on different design positions of the PCM layer at the heat exchanger, and for use in residential and office buildings. The results show that comparatively, the design with PCM located at the outermost layer of the heat exchanger has the best energy storage performance. For the case with PCM sealed in the middle annular space, the inner PCM layer is heated up rapidly, while the outer PCM layer remains at low temperature because of the continuous heat release to the cold water stream. With the use of PCM, 31.4% and 11.4% more hot water can be harvested during off-work hours for residential use in typical summer and winter weeks. And as a whole, the energy saving potential is greater in summer than in winter.

Fish assemblage production estimates in Appalachian streams across a latitudinal and temperature gradient

AbstractProduction of biomass is central to the ecology and sustainability of fish assemblages. The goal of this study was to empirically estimate and compare fish assemblage production, production‐to‐biomass (P/B) ratios and species composition for 25 second‐ to third‐order streams spanning the Appalachian Mountains (from Vermont to North Carolina) that vary in their temperature regimes. Fish assemblage production estimates ranged from 0.15 to 6.79 g m−2 year−1, and P/B ratios ranged from 0.20 to 1.07. There were no significant differences in mean assemblage production across northern cold‐water, southern cold‐water and southern cool‐water streams (p = .35). Two warm‐water streams, not included in these comparisons, had the highest mean production and biomass values. Mean assemblage P/B was significantly higher in northern cold‐water streams relative to southern cold‐water and cool‐water streams (p = .01). Species evenness in production declined with stream temperature and differed significantly across the lower latitude cold‐water, cool‐water and warm‐water streams and the higher latitude (i.e. more northern) cold‐water streams. Our fish assemblage production estimates and P/B ratios were both lower and higher compared to previously published estimates for similar stream habitats. This study provides empirical fish assemblage production estimates to inform future research on southern Appalachian streams and on the potential impacts of varying temperature regimes on cold‐water, cool‐water and warm‐water fish production in the coming decades as climate change continues to threaten fish assemblages.

Evaluation of the state of conservation of mosaics: Simulations and thermographic signal processing

Nondestructive inspection of mosaic structures is not a novelty in the thermographic scene. Interesting works can be retrieved from scientific literature, some of them dedicated to the use of static active configurations and/or the passive approach for the inspection of plastered mosaics or the assessment of mosaic floors. In the present study, a mosaic made by synthetic tesserae of different colors depicting a dove was inspected by active thermography using a static configuration. The mosaic was manufactured with artificial defects positioned at several depths and locations, where some of them, due to their dynamic nature, enabled the monitoring of their thermal effects over time. In particular, the mosaic contains: a void into which compressed air can be injected, a sponge insert that can be soaked by a known quantity of water through an external tube, and a sub-superficial recirculation circuit from which a stream of cold or hot water can flow. The variability of the nature of these defects, simulating what happens in a real case, was conveniently modeled by numerical simulation approaches. The latter point was assessed through the aid of a simulation software, while the comparison of the results obtained by numerical analysis with those derived by thermographic testing was also performed.

Liquid desiccant air conditioning system with natural convection

After introducing the concept of natural convection air dehumidifier system and establishing the feasibility of eliminating desiccant pump, this study aims to approve the application of natural liquid desiccant as an air conditioning system in real working conditions. The system consists of two heat/mass transfer modules: the absorber and the regenerator which are connected to constitute a closed loop. In each module hollow fiber membranes separate the air and desiccant streams. The liquid desiccant is aqueous solution of lithium chloride which is on the shell over the fiber surfaces and the air flows inside fiber lumens. The cold/hot water streams flow in the outer jackets of absorber/regenerator modules. The loop is redesigned to resolve the shortcomings of the previous design. The loop performance is studied experimentally under two inlet air conditions which resemble two climate conditions with relative humidity of 78% and 37% and temperature of 31.5°C. The evaluation indexes of system such as moisture absorption rate, cooling capacity and coefficient of performance (COP) are presented. The results show that the loop can act as a natural convection liquid desiccant air conditioning system with electrical COP values of 3.95 and 4.56 for higher and lower humidity ratio air inlets respectively. Also, it is resulted that the system has better performance in higher humidity air inlet. It is observed that main electric power consumption of the system is required for supplying cold water stream and the performance of system could enhances remarkably if a free cold water supply is available.

Long-term effects of channelization on a cold-water stream community

Stream channelization is a common form of anthropogenic disturbance, whose impacts on cold-water biological communities have received little attention in comparison with the body of work demonstrating its negative effects on lowland, warm-water systems. Furthermore, it has been suggested that physical stream processes, given sufficient temporal scale, are capable of restoring channelized reaches to their natural state; however, empirical evidence of this is lacking. Here, we examine the effects of stream channelization on fish and invertebrate communities and their habitats in disturbed and undisturbed cold-water mountain streams in southern Alberta, 80 years postchannelization. Our results show that negative impacts associated with channelization, such as a significant reduction of deep pools and loss of flow refugia, remain prevalent along impacted reaches, inhibiting the reestablishment of native species across multiple trophic levels. While these findings are applicable for a range of cold-water salmonid populations, we suggest that they may be of special importance to the management of mountain whitefish (Prosopium williamsoni) populations, which may be more sensitive to channelization than other cold-water species.

Fungi as Architects of the Rimstone Dams in Huanglong, NSD, Sichuan, China.

The Huanglong park area of the Sichuan Province of China is a unique scenic area of the world. It is known for its thousands of aquamarine-colored pools that are formed behind naturally formed rimstone dams of travertine (calcite) along a cold water stream. The travertine, based on its crystalline structural analysis, is of biological origin. This makes sense since the temperature of the waters of Huanglong varies from 5 to 7°C and thus geochemical crystallization does not occur as it does in other locations around the world possessing thermal pools whose structures are primarily formed through cooling processes. Fungi and bacteria were discovered associated with both leaves associated with the calcite dams as well as in the older parts of well-established dams. Several species of Phytium, a phycomycete and an endophyte, accounted for over 45% of all of the fungi successfully isolated from the well-established dam samples and at least 85% in the floating leaf samples. Saprolegnia spp. (Phycomycetes) along with Phoma spp. (Ascomycetes) were noted along with Mortierella sp. as other dam-associated fungi. The fungal hyphae observed on dead leaf material as well as in the calcite dams directly served as nucleation points for the formation of crystalline CaCO3. Eventually, these crystals grow large enough to fuse to make calcite plates which form the main structural feature of all of the travertine dams in this area. Interestingly, each of the individual crystals associated with the dams has an associated hole in its core where a fungal hypha used to reside as observed by scanning electron microscopy. While diatoms were present in the analysis, they too seem to contribute to the structure of the dams but in a minor way. The only bacteria isolated from the older dam of this aquatic environment were Pseudomonas spp. and their role in dam formation is uncertain. Huanglong is a unique and beautiful place, and the water features present in this area can definitely be attributed to those fungal architects that encourage calcite crystal formation.

Performance of Thermoelectric Module as a Water Cooler and Water Heater

This paper presents the total Coefficient of Performance (CoP) of a thermoelectric module in combined heating and cooling modes, obtained through experiments and thermodynamics mathematical model. Thermoelectric module is a solid state heat pump which has a capability to pump heat with the capacity of 100 W or lower. One of the module surface will acts as a heat sink while another surface of the module rejects heat. This provides an opportunity to utilize both surfaces for cooling and heating applications. The objective of this work was to determine the total CoP of the thermoelectric module when it was operated in a combination of heating and cooling modes. The total CoP was inferred by fitting the temperature of cold and hot water streams which were obtained from experiments to a mathematical model of the thermoelectric heating and cooling system. The highest temperature difference between hot and cold streams was 40 Kelvin. The worst root-mean-square error between the measured and calculated temperature was 2 Kelvin, except for the hot stream temperature curve in the Condition 1(RMS error was 3.5 Kelvin). It was proved that the total CoP of 4.5 was achievable for thermoelectric module operated in the combined heating and cooling modes. However, the total CoP decreased as the temperature difference between hot and cold streams was increased. It can be concluded that the use of thermoelectric module in heating and cooling modes can improve its CoP which contribute to saving in electrical consumption by the module.