- Differences among Expert Judgments of Fish Habitat Suitability and
Implications for River Management
- Authors: J. Radinger; J. Kail, C. Wolter
Abstract: Expert judgment is regularly used in ecology for assessing the suitability of habitats, in particular of rare or endangered species or species with limited empirical data. Yet, differences in expert judgment of habitat suitability and consequent implications for ecosystem management have not been evaluated and are largely ignored.Here, we evaluated the variability of 13 expert judgments and the related uncertainty in hydraulic habitat suitability modelling using the riverine fish species Phoxinus phoxinus as a model species.We found (i) the highest agreement among experts identifying the best and fully unsuited habitat conditions, but (ii) that disagreement among experts is surprisingly large, (iii) with largest differences related to the experts' perception of flow velocity and (iv) that semi-suitable transition areas between high and low habitat suitability are most susceptible to disagreements.We emphasize that expert judgment of habitat suitability is useful for many applications and especially highly suitable habitats would be reliably identified by experts. However, expert judgment-based assessments should be iterative processes that include both different experts and feedback on the potential effects of their assessments. Furthermore, we recommend that expert judgment should not replace data-driven empirical ecology but its benefits can rather complement it. Copyright © 2016 John Wiley & Sons, Ltd.
- Response of Bed Sediments on the Grade-Control Structure Management of a
Small Piedmont Stream
- Authors: T. Galia; V. Škarpich
Abstract: The grain sizes of 53 small lateral and mid-channel deposits were evaluated on the 2.7 km long channel-reach of a headwater piedmont stream that has been affected by check-dams and bed sills constructions (ca. 14 constructions per km), riprap bank stabilisations and the removal of instream wood. Such interventions have led to the loss of natural vertically oscillating bedforms, and pool-riffles have been replaced by plane beds. The evaluated sediment deposits were divided based on their positions relative to grade-control structures on downstream, intermediate and upstream types. The individual types of deposits produced different downstream trends in the grain sizes that reflected their positions with respect to the grade-control structures (GCSs). The downstream deposits generally produced slow downstream coarsening, which may point to the increased efficiency of the energy dissipation of the GCSs under a gradual downstream decrease in the channel slopes. However, they were generally not coarser than the other two types. The upstream deposits did not indicate any notable downstream grain-size trend. Despite the significant downstream decrease in the channel slopes and related bankfull shear stresses at the positions of the intermediate deposits and the lack of a lateral sediment supply in the studied longitudinal profile, the sediment calibre of the deposits did not produce any systematic downstream fining. Thus, the observed grain sizes most likely pointed to the selective scouring of the fine sediments, which was caused by the presence of the GCSs and their effects on the decreasing sediment connectivity. Copyright © 2016 John Wiley & Sons, Ltd.
- The Effects of Rapid Water Level Changes on Fish Assemblages: The Case of
a Spillway Gate Collapse in a Neotropical Reservoir
- Authors: M. T. Baumgartner; G. Baumgartner, L. C. Gomes
Abstract: River damming and associated reservoir causes intense and dramatic changes that create new environments, with particular structure and functioning. In these systems, flow control and artificial variations in water level are important determinants of the structure of fish assemblages. Planned reduction in water level (drawdown) is used to manage productivity in reservoirs. However, the effects of non-planned reductions, such as those related to the collapse of spillway gates, are rarely studied. The objective of this study was to evaluate the effects of a rapid reservoir drawdown, because of the collapse of a gate, on the structure of fish assemblage in a Neotropical reservoir, in Southern Brazil, operated as run-of-the-river. Water level variation because of the collapse reached up to 20 m. A canonical analysis of principal coordinates (CAP) was used to summarize the structure of fish assemblage. Spearman rank correlations were performed between each CAP axes retained for interpretation and fish species abundances, to assess the ones that most contributed to observed patterns. The first CAP axis identified strong variations in the spatial scale, while the third axis identified variations in the time scale (before and after the collapse). The most notable negative effect was the loss of several fish that perished during the reservoir drawdown, probably because of adverse limnological conditions. Results showed significant benefits of water level variation on the entire fish assemblage, and we suggest that, observed some peculiarities, this variation can be used to manage reservoirs, as a tool to enhance fish abundances. Copyright © 2016 John Wiley & Sons, Ltd.
- Reinforcement and Validation of the Analyses and Conclusions Related to
Fishway Evaluation Data from Bunt et al.: ‘Performance of Fish Passage
Structures at Upstream Barriers to Migration’
- Authors: C. M. Bunt; T. Castro-Santos, A. Haro
Abstract: Detailed re-examination of the datasets that were used for a meta-analysis of fishway attraction and passage revealed a number of errors that we addressed and corrected. We subsequently re-analysed the revised dataset, and results showed no significant changes in the primary conclusions of the original study; for most species, effective performance cannot be assured for any fishway type.
- Trend Analysis of Maximum Hydrologic Drought Variables Using
Mann–Kendall and Şen's Innovative Trend Method
- Authors: F. Tosunoglu; O. Kisi
Abstract: Droughts as destructive climatic extreme events affect natural environment of an area. Identifying droughts has a vital importance in the planning and management of water resource systems of a river basin. This study investigates the trends of maximum hydrologic drought variables, annual maximum duration (AMD), and annual maximum severity (AMS), by using Mann–Kendall, modified Mann–Kendall, and recently developed Şen's innovative trend analysis (ITA) methods. These methods are applied to the AMD and AMS of nine different stations located in Coruh River Basin, Turkey, in which numerous highly critical power plants have recently been constructed, under construction, or planned. Basic Mann–Kendall test indicated no trend in the investigated stations while the modified Mann–Kendall gave significantly decreasing trend for AMS series of station 2304 and for AMD series of station 2321 at 10% significance level. Modified Mann–Kendall and ITA approaches indicate that the AMS of station 2304 show significantly decreasing trend. According to the ITA method, the peak AMS values of the stations 2315 and 2322 have also significantly decreasing trend after 1986. Both modified MK and ITA methods provide increasing trends in drought severities of the stations 2316 and 2323. It should be noted that some droughts or water stress may be occurred in these stations in the future. Modified Mann–Kendall test provides no significant trend for the seven stations while ITA results indicated some positive or negative trends at these stations. The primary points of interest of Şen's ITA method are that it is not subject to any assumption such as serial relationship, non-normality, sample size, and trends of low, medium, and high data can be seen by this method easily. The study indicates that the ITA method could be simply and successfully used by hydrologist or water resources decision makers or in identifying droughts to prepare efficient management plans. Copyright © 2016 John Wiley & Sons, Ltd.
- Identification of Priority Areas for the Conservation of Stream Fish
Assemblages: Implications for River Management in France
- Authors: A. Maire; P. Laffaille, J.-F. Maire, L. Buisson
Abstract: Financial and human resources allocated to biodiversity conservation are often limited, making it impossible to protect all natural places, and priority areas for protection must be identified. In this study, we applied ecological niche models to predict fish assemblages in the stream network of France. Four non-correlated conservation objectives were derived from these species assemblages: taxonomic diversity, functional diversity, natural heritage importance and socio-economic value. We proposed a multi-objective prioritization method based on the Pareto optimality principle to rank the planning units (i.e. 6097 subcatchments) according to their inherent trade-offs between the four conservation objectives. Four types of hydrosystems of great conservation importance presenting specific fish assemblages were identified: (i) the most upstream areas of large catchments; (ii) the most downstream areas of large catchments; (iii) the small coastal catchments of the English Channel and the Atlantic Ocean; and (iv) the Mediterranean streams of medium altitude. The fish assemblages characterizing these hydrosystems were complementary and representative of the entire fish fauna of France. Most of these priority subcatchments were found to be practically suitable for the implementation of conservation actions, which is very promising for the protection of river biodiversity. Copyright © 2016 John Wiley & Sons, Ltd.
- Effects of Damming on Long-Term Development of Fluvial Islands, Elbe River
- Authors: P. Raška; M. Dolejš, M. Hofmanová
Abstract: Damming and water impoundment have fundamental influences on the geomorphology and ecological processes of lotic systems. Although these engineering projects affect all segments of the river channel, fluvial (mid-channel, river) islands are among the most threatened features because of their link to both hydrostatic and hydrodynamic effects of damming. In this study, we used historical maps (1843, 1852) and aerial photos (1954, 2014), as well as other written and iconographic documentary sources, to document the long-term development of the fluvial islands and channel planform in the Lower Labe (Elbe) River area (Northern Czechia) over the past ~170 years. Our results indicate the decrease of fluvial islands from 16 (1843), resp. 20 (1852) in the mid-19th century to eight in 1954, and finally to five in 2014. Most islands have disappeared because of the construction of dams and lock chambers for the purpose of river navigation in the first half of the 20th century. The possible processes responsible for island extinction in individual river segments include sediment starvation (downstream of the dam), erosion by overflow (near upstream of the dam) and decreased flow in inter-island branches (far upstream of the dam). The islands most susceptible to extinction are those with a smaller size and elliptical or irregular shape. Based on visual evaluation of historical photos and survey of present day temporary islands, the medium and fine sedimentary fraction and absence of a vegetation cover seem to be another predictor of island extinction. Finally, we stress the relevance of our findings for the current discussion on the construction of new lock chambers downstream of the study area. Copyright © 2016 John Wiley & Sons, Ltd.
- Hydropower Plant Operation Scenarios to Improve Brown Trout Habitat
- Authors: I. Pragana; I. Boavida, R. Cortes, A. Pinheiro
Abstract: In this study, different hydropower plant operation scenarios were proposed to assess the best habitat alternative for juvenile and adult brown trout (Salmo trutta). Habitat preferences were determined based on field data collection and translated into fuzzy sets and rules for both life-stages. The River2D model was applied to a 100-m long stream segment immediately downstream of the tailrace of the Ermida small hydropower plant (SHP) to obtain a 2D hydrodynamic description for different operation scenarios. Habitat modelling was performed using Casimir Fish 2D by combining flow and fuzzy rules. Overall, simulation results for the juveniles indicated its best habitat conditions for discharges between 0.5 and 1.0 m3s−1 and the adults for 5.0 m3s−1. Five main operation scenarios were developed according to the electricity pricing periods for dry, average and wet year. The decrease in energy revenue was calculated for each operation alternative. The results indicate that it was possible to reduce hydropeaking effects in brown trout habitat through changes in the hydropower plant operation especially for dry years. The methodology developed in this research should be seen as a decision-making tool to help water managers adapt hydropeaking regimes to reduce the ecological impact downstream of hydropower dams. Copyright © 2016 John Wiley & Sons, Ltd.
- Tracking Change in the Illinois River using Stable Isotopes in Modern and
- Authors: R. B. Brugam; K. Little, L. Kohn, P. Brunkow, G. Vogel, T. Martin
Abstract: The Illinois River has been heavily modified by human activities. We examined the nitrogen and carbon stable isotope composition of collagen from fish bones in two Native American middens comparing them to modern fishes in the River today. We also compared ancient and modern fishes to three reference samples—(i) Illinois River phytoplankton; (ii) backwater lake sediment; and (iii) tissue from riverside trees. We found a large increase in δ15N values in modern fish bone collagen relative to ancient collagen. However, there is little change in δ13C between ancient and modern samples. Bone collagen from invasive carp species (Hypopthalmichthys and Cyprinus) are similar to modern phytoplankton. All fishes are different from riverside trees and backwater lake sediment. The large shift in δ15N values between ancient and modern fishes is probably caused by contamination of the river by Chicago treated wastewater and by denitrified fertilizer run-off. Our results indicate a major change in nitrogen biogeochemistry in the modern river. Comparisons between ancient and modern δ13C values suggest little change in feeding behaviour of fishes between ancient and modern times. However, our data for invasive carp suggest strong competition with native planktivores. © 2016 The
Authors . River Research and Applications Published by John Wiley & Sons Ltd.
- The Impacts of Natural Flood Management Approaches on In-Channel Sediment
- Authors: V. J. Janes; R. C. Grabowski, J. Mant, D. Allen, J. L. Morse, H. Haynes
Abstract: Natural Flood Management (NFM) techniques aim to reduce downstream flooding by storing and slowing the flow of stormwater to river channels. These techniques include a range of measures, including setback stormwater outfalls and the physical restoration of channels and floodplains, to improve the natural functioning of catchments. An additional benefit of NFM measures is the potential reduction in sediment and pollutant delivery to the channel. Urban development releases a variety of heavy metal and nutrient pollutants that enter rivers through stormwater outfalls with adverse effects on the aquatic ecosystem. In this study, the influence of channel modification and quality of the river habitat on the sediment quality surrounding stormwater outfalls was assessed. Sediment samples were taken at several outfalls within the Johnson Creek catchment, Oregon, USA, and analysed for a variety of urban pollutants. The level of river habitat quality and modification at each site were assessed using a semi-quantitative scoring methodology. Significant increases in pollutant levels were observed at outfalls, with a greater and more variable increase at direct compared to setback outfalls. Removal efficiency of certain pollutants was found to be significantly correlated to the level of habitat quality or modification (for Fe, Ba, Sn, Mg, P, K) indicating that more natural reaches had greater potential for pollutant removal. The findings highlight the multiple benefits associated with NFM and river restoration approaches in relation to sediment quality and pollutant content. © 2016 The
Authors River Research and Applications Published by John Wiley & Sons, Ltd.
- Flood Effects Provide Evidence of an Alternate Stable State from Dam
Management on the Upper Missouri River
- Authors: K. Skalak; A. Benthem, C. Hupp, E. Schenk, J. Galloway, R. Nustad
Abstract: We examine how historic flooding in 2011 affected the geomorphic adjustments created by dam regulation along the approximately 120 km free flowing reach of the Upper Missouri River bounded upstream by the Garrison Dam (1953) and downstream by Lake Oahe Reservoir (1959) near the City of Bismarck, ND, USA. The largest flood since dam regulation occurred in 2011. Flood releases from the Garrison Dam began in May 2011 and lasted until October, peaking with a flow of more than 4200 m3 s−1. Channel cross-section data and aerial imagery before and after the flood were compared with historic rates of channel change to assess the relative impact of the flood on the river morphology. Results indicate that the 2011 flood maintained trends in island area with the loss of islands in the reach just below the dam and an increase in island area downstream. Channel capacity changes varied along the Garrison Segment as a result of the flood. The thalweg, which has been stable since the mid-1970s, did not migrate. And channel morphology, as defined by a newly developed shoaling metric, which quantifies the degree of channel braiding, indicates significant longitudinal variability in response to the flood. These results show that the 2011 flood exacerbates some geomorphic trends caused by the dam while reversing others. We conclude that the presence of dams has created an alternate geomorphic and related ecological stable state, which does not revert towards pre-dam conditions in response to the flood of record. This suggests that management of sediment transport dynamics as well as flow modification is necessary to restore the Garrison Segment of the Upper Missouri River towards pre-dam conditions and help create or maintain habitat for endangered species. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
- An Objective Method to Prioritize Socio-Environmental Water Management
Tradeoffs Using Multi-Criteria Decision Analysis
- Authors: D. M. Martin; S. J. Powell, J. A. Webb, S. J. Nichols, N. L. Poff
Abstract: Rivers provide many social and environmental services that benefit humanity. A critical role of water mangers is to prioritize water allocation options that trade off socio-economic and hydro-ecological benefits in rivers. Methods for multi-criteria decision analysis (MCDA) provide a structured and systematic manner for researchers to aid in this process. In this paper, we describe a new MCDA method that prioritizes large multi-dimensional sets of tradeoffs to support well-informed water management in rivers. The method was developed based on an environmental flows planning study in the Goulburn-Broken River catchment, Victoria, Australia. A combined simulation and heuristic optimization procedure was previously integrated into a hydrological catchment network model. That process resulted in a large set of viable daily water allocation schedules that traded off long-term irrigation and hydro-ecological benefits at the catchment outlet. We provided new guidance procedures to identify priority tradeoffs that can be used in stakeholder deliberations and catchment decision-making. Our MCDA method included combined multi-dimensional ordination and cluster analysis to spread the water allocation alternatives onto a two-dimensional plane to discover alternatives with similar criteria tradeoffs. A geometric distance-based method was performed on the full set of alternatives and on the identified clusters to rank the alternatives in accordance with minimizing the distance of the alternatives to an ideal but non-feasible reference point in multi-dimensional space. This method complements the use of elicitation procedures when water manager or other stakeholder interaction is not an option or when objectivity is desired. Copyright © 2016 John Wiley & Sons, Ltd.
- Meta-analyses, Metrics and Motivation: Mixed Messages in the Fish Passage
- Authors: P. S. Kemp
Abstract: Over recent years, there has been increasing challenge to the accepted wisdom that the environmental impacts of river engineering can be adequately mitigated through the installation of infrastructure, such as fish passes. This has led to a debate on the value of fish passage with some arguing that increased research and development will advance solutions for a variety of structures that are suitable for multiple species and transferable to different regions. Others suggest that policies and management strategies should reflect the realization that current mitigation technology frequently fails and can itself have negative impacts. Meta-analyses of the results of studies on fish passage effectiveness have led to the challenge of conventional views by highlighting lower than expected efficiencies, wide variation between and within fish pass designs, and bias towards consideration of a limited number of commercially important species mainly from northern temperate regions. Results of meta-analyses can also be controversial, and difficulties can arise when nuances associated with individual studies are lost and when metrics used are not standardized. Intrinsic variation in fish passage efficiency between and within species due to differences in patterns of movement and motivation may not be considered, and in many situations, current metrics are not appropriate. Quantification of variation in trends in fish passage efficiency over time and with spatial scale is lacking and should be the focus of future reviews. It is time to accept that fish passage does not provide a universally effective mitigation solution, particularly when designs and strategies are transferred to other regions and species for which they were not originally designed. Admitting to cases of failure is an essential first step to advancing water resources planning and regulation based on well-informed decision-making processes. Copyright © 2016 John Wiley & Sons, Ltd.
- Macroinvertebrate Functional Trait Responses to Chemical Pollution in
- Authors: M. Pallottini; D. Cappelletti, A. Fabrizi, E. Gaino, E. Goretti, R. Selvaggi, R. Céréghino
Abstract: Both physical–chemical and biological indicators are used to assess the ecological health of ecosystems. The functional trait composition of communities has the potential to predict the impact of environmental change on ecosystems, yet, we miss evidence that information on pollution can be used to forecast the functional responses of freshwater communities. We used chemical and ecological data collected in the Nestore river basin (Central Italy) to test whether (i) there are generalities in the response of macroinvertebrate functional diversity to river pollution; (ii) water pollution filters certain functional traits and (iii) traits do better than chemical analyses at revealing ecological stress in rivers. Due to interactions with hydrology, chemical variables showed higher seasonal variation at impacted sites, so occasional water samples represented snapshots. Functional traits did well at detecting water pollution by various chemicals, and there was a clear shift of trait combinations from unimpacted to impacted sites. Anthropogenic disturbances homogenized benthic communities in terms of taxonomic and functional composition, both in space (impacted sites) and time (seasons). Traits related to feeding habits (mainly reliance on fine particulate organic matter) and tolerance to organic pollution were prevalent at impacted reaches, and functional trait compositions were more stable than water chemistry over seasons because they integrate environmental conditions over longer time periods. Functional traits can play a relevant role in the bioassessment of polluted river ecosystems, even under low to moderate disturbance. Trait-based assessment can be complemented by chemical analyses, notably at highly polluted sites where biological diversity drops to its lowest levels. Copyright © 2016 John Wiley & Sons, Ltd.
- Factors Influencing Movements of Two Migratory Fishes within the Tailrace
of a Large Neotropical Dam and their Implications for Hydropower Impacts
- Authors: F. M. Suzuki; J. B. Dunham, L. G. M. Silva, C. B. M. Alves, P. S. Pompeu
Abstract: Fish attempting to move upstream through hydroelectric dams can be trapped and killed in turbines. Understanding fish movement patterns can provide useful insights for how to manage dam operations to minimize fish kill in turbines. We evaluated the movements of two migratory fish (Curimba—Prochilodus argenteus and Mandi—Pimelodus maculatus) using acoustic telemetry in the tailrace of Três Marias Dam (São Francisco River, Brazil) from 31 October 2011 to 16 February 2012. The majority of tagged fish left the tailrace in less than one week; however, some individuals returned, performing several visits to the tailrace. Mandi remained longer in the tailrace than Curimba. The number of visits was influenced by diel period, turbine and spillway discharge. Although the diel period was the only important contributor to the visits performed by Curimba, the movements of Mandi were significantly influenced by three factors. We found that whereas Curimba was predominantly diurnal, Mandi showed nocturnal habits. Additionally, visits of Mandi were significantly greater during higher turbine and spillway discharge. We discuss the implications of these results for understanding fish movements in the Três Marias Dam tailrace and their potential implications for adapting hydroelectric operations to minimize fish kills. Copyright © 2016 John Wiley & Sons, Ltd.
- Long-term Hydrologic Variability in a Large Subtropical Floodplain River:
Effects on Commercial Fisheries
- Authors: A. P. Rabuffetti; K. Górski, L. A. Espínola, E. Abrial, M. L. Amsler, A. R. Paira
Abstract: We analysed the effects of decadal and annual hydrologic fluctuations on freshwater fisheries catches in the Middle Paraná River for a period of six decades from the 1930s to the 1980s. The climatic fluctuations in this period strongly affected the hydrology of the Middle Paraná River and the characteristics of its flow regime. The magnitude of floods as well as maximum, minimum and mean water levels increased progressively from 1930s until the 1980s concomitantly with increasing frequency and intensity of El Niño Southern Oscillation events that resulted in differentiation of distinct hydrological periods. The flood pulses were significantly more frequent and of greater magnitudes during the 1970s and 1980s. These large floods resulted in increased commercial fish catches in the 1980s, possibly because of enhanced recruitment. Specifically, large floods increased the commercial fish catches 2 years later. This effect was stronger for species that use floodplain habitats as areas of reproduction and larval nurseries, such as Prochilodus lineatus. We conclude that the natural flow regime of the Paraná River and perhaps other large subtropical rivers must be preserved in order to sustain their productive fisheries. Copyright © 2016 John Wiley & Sons, Ltd.
- Evaluation of Central Valley Spring-Run Chinook Salmon Passage Through
Lower Butte Creek Using Hydraulic Modelling Techniques
- Authors: W. R. Cowan; D. E. Rankin, M. Gard
Abstract: River2D was used to develop a hydraulic model of an upstream passage impediment for adult spring-run Chinook salmon (Oncorhynchus tshawytscha) on Butte Creek, Tehama County, California. Topographic data were collected by using a total station, survey-grade real-time kinematic global positioning system, and terrestrial light detection and ranging. Stage-discharge relationships were developed at the upstream and downstream ends of the site to use as boundary conditions and to calibrate the 2D model. A pressure transducer was installed at the downstream boundary of the site to provide a time series of flow and water temperatures. Parameters of the hydraulic model were examined to assess upstream passage including minimum thalweg depth along the least width-limiting pathway, velocity, and water surface elevation above and below a jump, and flow partitioning between a split in the main flow paths through the site. The results of the River2D model were used to identify flow levels that met the minimum depth and width thresholds needed for adult spring-run Chinook salmon (SRCS) to migrate upstream through the study reach. A minimum passage depth criterion of 0.27 m was used for adult SRCS. Site-specific passage width criteria were derived from the literature for the study site and ranged from 0.3 to 0.9 m. Model results indicated that a flow of 3.40 cms met the depth criterion and the lower bound of the width criterion. A flow level of 6.8 cms met the depth criterion and the upper bound of the width criterion. Data from the VAKI Riverwatcher fish passage counting device installed just upstream of the study site were related to the stage/passage limiting width and water temperature monitoring data. The monitoring data and results of the predictive modelling will be used by the California Department of Fish and Wildlife to recommend flow criteria that protect migrating adult SRCS. Copyright © 2016 John Wiley & Sons, Ltd.
- Block Ramps in Curved Rivers: Morphology Analysis and Prototype Data
Supported Design Criteria for Mild Bed Slopes
- Authors: S. Pagliara; A. Radecki-Pawlik, M. Palermo, K. Plesiński
Abstract: Eco-friendly river restoration structures are a valid solution for river training projects. Among this structure typology, block ramps have been successfully tested to solve problems related to river sediment control, bed stabilization and energy dissipation. Despite the conspicuous literature dealing with block ramps design in straight rivers, there are no studies analysing the erosive process occurring in the stilling basin downstream of a block ramp in a curved river bend. Therefore, this paper represents the first systematic analysis of their behaviour and of the resulting downstream equilibrium morphology in such geometric configuration. A dedicated model was built to simulate a wide range of hydraulic conditions. Experimental data analysis allowed describing the erosion dynamics occurring in the stilling basin and, at the same time, to derive a useful design relationship by which it is possible to estimate the maximum scour depth. Furthermore, the model results were successfully validated by using field measurements collected in the Porębianka River (Poland). Both field data and laboratory experimental results allowed furnishing a comprehensive description of the scour phenomenon. The proposed relationship represents the first trustable and valid tool for hydraulic design of such structure typology in curved rivers. Copyright © 2016 John Wiley & Sons, Ltd.
- Dissolved Oxygen Relationships of Under-Ice Water Column and Pore Water
Habitat: Implications for Environmental Guidelines
- Authors: J. M. Culp; E. Luiker, N. E. Glozier, M. Meding, D. Halliwell, F. J. Wrona
Abstract: Substantial reductions in dissolved oxygen concentration in freshwaters can negatively affect aquatic biota. Thus, existing regulatory criteria are designed to avoid environmental conditions that cause acute lethality, thereby reducing the likelihood of biological impairment. In North America, dissolved oxygen (DO) guidelines for protecting aquatic life assume that pore water and water column DO are correlated, with pore water values expected to be on average ≤3 mg/L below water column values. Our study assessed the validity of this assumption during the winter period of ice cover in a large, northern river ecosystem (Wapiti River, Alberta, Canada). We investigated the relationship between water column and pore water DO concentrations and examined whether this relationship was affected by industrial and municipal effluents. Water column DO fell from near saturation during open water periods to 80–84% under winter ice cover. DO concentrations in the pore water were significantly lower than in the water column at reference and effluent-exposed sampling sites. Pore water DO values ranged widely from 0.27 to 13.28 mg/L. In contrast, water column DO concentrations (10.25–13.60 mg/L) were more narrowly distributed over the same period. Indeed, differences between winter pore water and water column DO were often as large as 9–12 mg/L and, notably, were significantly greater than the 3 mg/L difference upon which North American guidelines are based. Consequently, under-ice DO concentrations of river pore water could not be accurately predicted from water column DO alone. Risk factors that may increase the potential for pore water DO to be more than 3 mg/L lower than water column values include the input of oxygen poor groundwater, infilling of the streambed with small inorganic and organic particles, water exchange rates between the water column and the streambed and effluent discharges that raise nutrient concentrations and biochemical oxygen demand. Given that low pore water DO was evident even in undeveloped reference sites, future work must establish the ecological relevance of chronic exposure to low, pore water DO and its impact on river biota. © 2016 Environment and Climate Change Canada. River Research Application © 2016 John Wiley & Sons, Ltd.
- A Comparison of Metabolic Rates in Off-Channel Habitats of the Middle
- Authors: M. J. Sobotka; Q. E. Phelps
Abstract: Autochthonous material has been found to be an important base in large river food webs. However, a spatial understanding of primary production in large rivers is lacking. We modeled primary productivity and community respiration (CR) during a low water period in two types of off-channel habitat present in the Middle Mississippi River, side channels and wing dike fields. Wing dike fields are constantly connected to the main channel and are well mixed along most of their length, while side channels are typically connected only at the top and mouth. Gross primary production (GPP) in wing dike fields ranged from 0.0 to 8.9 g O2 m−2 D−1 and in side channels GPP ranged from 0.4 to 33.5 g O2 m−2 D−1. Both habitat types experienced periods of positive net ecosystem production (NEP) especially in the late summer and early fall. Correlations between metabolic rates and ecosystem characteristics differed between habitat types. Discharge was negatively correlated to NEP in wing dike fields but was not associated with metabolic rates in side channels. Light was positively correlated with GPP and CR at both site types and with NEP in side channels. These areas are protected from high velocity and likely experience greater light penetration, allowing more photosynthesis to take place especially during low water periods. This study demonstrates the potential for high productivity in off-channel habitats that are permanently connected to the main channel. Copyright © 2016 John Wiley & Sons, Ltd.
- Benchmarking Fluvial Dynamics for Process-Based River Restoration: the
Upper Rhine River (1816–2014)
- Authors: M. Diaz-Redondo; G. Egger, M. Marchamalo, S. Hohensinner, E. Dister
Abstract: Multi-temporal analysis of river-floodplain processes is a key tool for the identification of reference conditions or benchmarks and for the evaluation of deviations or deficits as a basis for process-based river restoration in large modified rivers. This study developed a methodology for benchmarking fluvial processes at river segment level, focusing on those interrelations between morphodynamics (aggradation, erosion, channel shift) and vegetation succession (initial, colonization, transition) that condition habitat structure. Habitat maps of the free-flowing Upper Rhine River downstream from Iffezheim dam (France–Germany border) were intersected with a geographic information system-based approach. Patches showing trajectories of anthropization, changeless, progression and regression allowed for the identification of natural and human-induced processes over almost 200 years. Before channelization, the riverine system was characterized by a shifting habitat mosaic with natural heterogeneity, high degree of surface water connectivity and equilibrium between progression and regression processes. On the other hand, the following 175 years of human interventions led to severe biogeomorphologic deficits evidenced by loss of natural processes and habitat heterogeneity, hydrological disconnection between the river and its floodplain and imbalance of progression versus regression dynamics. The main driving forces of change are found in hydromorphological impacts (channelization, regulation and hydropower plant construction). Regression processes are now almost absent and have to be the objective of process-based river restoration measures for the studied river-floodplain system. A sustainable view on water management and river restoration should aim at a more resilient riverine system by balancing the recovery of natural processes with societal needs. Copyright © 2016 John Wiley & Sons, Ltd.
- Commentary—Incorrect Application of Data Negates Some Meta-analysis
Results in Bunt et al. (2012)
- Authors: J. G. Williams; C. Katopodis
- The Interplay between Environmental Conditions and Filamentous Algae Mat
Formation in Two Agricultural Influenced South African Rivers
- Authors: P. J. Oberholster; V. S. Somerset, J. C. Truter, A.-M. Botha
Abstract: The regulation of nutrient inputs into rivers dominated by agriculture land use activities is an important aspect of ecological resilience of aquatic systems and the management of river eutrophication. The overabundance of benthic filamentous algae mats in river systems due to nutrient enrichment can modify the habitats of macroinvertebrate and fish communities as well as clogging irrigation crop sprayers of downstream water users. The current study examined over a period of 2 years (2013–2014) the interplay between physical and chemical river characteristics and epilithic filamentous algae biomass in two South African agricultural influenced rivers. The study area consisted of the Touw and Duiwe Rivers, which run into a proclaimed Ramsar site, namely, the Wilderness Lake System. A strong positive correlation was observed between the maximum filamentous algae biomass (97 chl-a mg m−2) observed during the dry season and the average water column alkalinity >30 mg l−1. The benthic trophic status of the nine sampling sites during the dry seasons indicated the highest benthic algae biomass with mesotrophic (1.7–21 chl-a mg m−2) to hypertrophic (>84 chl-a mg m−2) conditions. During the dry season, only three sampling sites were below the suggested guideline value (35 µg l−1) for total phosphorus (TP), while four sampling sites were below the total nitrogen guideline of 252 µg l−1. In the wet season, two sites were below TP values with five sites below total nitrogen guideline values. From the data gathered, it was evident that water column alkalinity and hardness were the main drivers for the formation or absence of benthic filamentous algae mats in the two river systems and that nitrogen and/or phosphorus concentrations was overshadowed by the physical and chemical characteristics of the river systems at certain sites. Nutrient results for the river bottom sediments revealed that the sediment qualities were variable at the different sampling sites, but more specifically along the longitudinal paths of flow. It was apparent that the high TP concentrations in the water column and bottom sediment, which were lowest during the dry season, were associated with the highest epilithic filamentous algae mat formation. The outcome of the current study shows that a more holistic approach must be followed for the development of future eutrophication guidelines and nutrient thresholds in South African rivers influenced by agriculture land use activities. Copyright © 2016 John Wiley & Sons, Ltd.
- Chemical and Isotopic Tracer Evaluation of Water Mixing and Evaporation in
a Dammed Texas River During Drought
- Authors: A. A. Vanplantinga; E. L. Grossman, E. B. Roark
Abstract: The interaction between drought and river regulation is monitored to better understand river flow mixing, evaporation and surface-groundwater exchange in changing regional climates and in increasingly regulated waterways. This study compared Brazos River stable isotope (δ18O and δD) and electrical conductivity values with reservoir, creek and aquifer samples in the Brazos watershed, the largest watershed in Texas. The combination of tributaries, rainfall and the Brazos River Alluvium Aquifer, on the one hand, and the Lake Whitney reservoir, on the other hand, represent endmembers of dilute run-off water and evaporated saline water, respectively. A simple isotope mixing model that uses monthly river discharge, Lake Whitney discharge, historical monthly precipitation δ18O and pan evaporation accurately reconstructs river δ18O (±0.5‰ on average). Data and isotope balance modelling support continued evaporation of 18O-enriched Lake Whitney water as it flows downstream, although the most evaporation took place in Lake Whitney. The difference between river and precipitation δ18O, or Δ18ORIV-PPT, here a measurement of degree of evaporation, ranged from −0.1‰ for a small creek, to 1.7‰ for the Brazos River, to at least 2.7‰ in Lake Whitney. This study indicates that drought in regulated rivers may enhance reservoir discharge dominance in river flows during peak drought conditions when combined run-off and baseflow dominance would be expected in a similar undammed river. Copyright © 2016 John Wiley & Sons, Ltd.
- Quantifying Submerged Deposited Fine Sediments in Rivers and Streams Using
Digital Image Analysis
- Authors: M. D. Turley; G. S. Bilotta, G. Arbociute, R. P. Chadd, C. A. Extence, R. E. Brazier
Abstract: Deposited fine sediment is an essential component of freshwater ecosystems. Nonetheless, anthropogenic activities can modify natural fine sediment levels, impacting the physical, chemical and biological characteristics of these ecosystems. An ability to quantify deposited fine sediment is critical to understanding its impacts and successfully managing the anthropogenic activities that are responsible for modifying it. One widely used method, the visual estimate technique, relies on subjective estimates of particle size and percentage cover. In this paper, we present two novel alternative approaches, based on non-automated digital image analysis (DIA), which are designed to reduce the subjectivity of submerged and surficial fine sediment estimates, and provide a verifiable record of the conditions at the time of sampling. The DIA methods were tested across five systematically selected, contrasting temperate stream and river typologies, over three seasons of monitoring. The resultant sediment metrics were strongly, positively correlated with visual estimates (rs = 0.90, and rs = 0.82, p
- The Importance of Shallow-Low Velocity Habitats to Juvenile Fish in the
Middle Mississippi River
- Authors: S. A. Love; Q. E. Phelps, S. J. Tripp, D. P. Herzog
Abstract: Habitat management is a crucial aspect of fisheries management. Without knowledge of habitat associations, fisheries scientists are unable to effectively make habitat conservation or restoration recommendations. This becomes especially prominent when trying to manage commercially harvested populations and protect threatened or endangered species. To determine juvenile fishes habitat associations in the Middle Mississippi River, we analysed mini-trawl catch data of six common juvenile fish species: blue catfish (Ictalurus furcatus), channel catfish (Ictalurus punctatus), channel shiner (Notropis wickliffi), freshwater drum (Aplodinotus grunniens), paddlefish (Polyodon spathula), and shovelnose sturgeon (Scaphirhynchus platorynchus). Overall, we conducted 2251 mini-trawl sampling efforts between 2002 and 2013, resulting in the capture of 23,742 target specimens. Catch per unit effort was evaluated by structural habitat (i.e. velocity, depth, and substrate). Overall, these data suggest that juvenile fish species are more prevalent in shallow water and slower velocities. Ultimately the information garnered during this evaluation should be incorporated when considering habitat modifications, especially those modifications that impact the availability of shallow-low velocity habitats. Copyright © 2016 John Wiley & Sons, Ltd.
- A Fuzzy Rule-based Model for the Assessment of Macrobenthic Habitats under
- Authors: M. Schneider; I. Kopecki, J. Tuhtan, J. F. Sauterleute, P. Zinke, T. H. Bakken, T. Zakowski, S. Merigoux
Abstract: Hydropeaking presents one of the large impacts on river ecology and is gaining importance because of an increasinlgy volatile energy market with high portions of new renewable energies dependent on local climate conditions. This study presents the application of a fuzzy logic model for the investigation of macrobenthic habitats under hydropeaking conditions in the Norwegian river Surna. Preference data of the three taxa Baetis rhodani, Hydroptila spp. and Allogamus auricollis with distinctively different habitat requirements related to near-bottom flow forces (high/low forces, and narrow range) are used. These data are transferred into the multivariate fuzzy rule-based physical habitat model Computer Aided Simulation of Instream flow and Riparia in order to integrate water depth and river bed substrate as additional parameters. Permanently available habitats (persistent habitats) are assessed for different scenarios of hydropeaking operation. It is found that the amount of persistently high-quality habitat is closely related to the size and range of fluctuations in hydraulic conditions occuring during hydropeaking events. Effects are much more distinct for species with a narrow range of hydraulic preference. The integration of water depth in the simulations has a noticable impact on the amount and quality of predicted habitats. Substrate conditions in the investigation site are homogeneous and, in the specific case considered, do not have a significant impact. The study suggests persistent habitats as a suitable indicator of hydropeaking impact on organisms with low mobility. The persistent habitat approach takes into account that organisms with a low mobility and a distinct range of tolerance related to hydraulic stress tend to settle in areas with permanently stable conditions. Multivariate aspects are accounted through the fuzzy rule-based approach and do clearly affect habitat predictions. Habitat requirements of species particularly sensitive to hydropeaking are proposed for the investigation and application in the future. Copyright © 2016 John Wiley & Sons, Ltd.
- Water Quality Changes Shortly After Low-Head Dam Removal Examined With
Cultural and Microbial Source Tracking Methods
- Authors: Z. Bohrerova; E. Park, K. Halloran, J. Lee
Abstract: Short-term effects of low head dam removal on water quality of urbanized stream were evaluated, focusing on fecal pollution indicators. Composite river samples were analyzed for Escherichia coli concentrations, nitrates, phosphates, turbidity and human-specific marker (HF183) and antibiotic resistance marker (tetQ) before and after dam removal during dry weather conditions. The sampled Olentangy River water in summer before the dam removal showed poor water quality with mean E. coli concentration of 439 colony forming unit (CFU)/100 mL, mean turbidity of 10 NTU and mean nutrient concentrations of 0.61 and 0.41 mg/L for nitrate and phosphate, respectively. Surprisingly, even one month after the dam removal, E. coli numbers doubled and nitrate concentration tripled compared to pre-removal concentrations. Although the detected HF183 concentrations were below the quantifiable levels, they did not correlate with E. coli concentrations, suggesting E. coli from other than human fecal origin. The correlation between turbidity and E. coli during dry weather further suggests E. coli accumulation in impoundment sediments and release once dam was removed. These short-term effects of dam removal on water quality should be further evaluated, especially if recreation and other beneficial uses of water in the area are expected. Copyright © 2016 John Wiley & Sons, Ltd.
- Growth, Condition and Survival of Three Forage Fish Species Exposed to Two
Different Experimental Hydropeaking Regimes in a Regulated River
- Authors: B. Kelly; K. E. Smokorowski, M. Power
Abstract: Hydroelectric dam operation can alter discharge and temperature patterns, impacting fish populations downstream. Previous investigations into the effects of river regulation on fish have focused on a single species within a river, yet different results among studies suggest the potential for species-specific impacts. Here, we compare the impacts of two different hydropeaking regimes relative to a naturally flowing river on three ecologically important members of the forage fish community: longnose dace (Rhinichthys cataractae), slimy sculpin (Cottus cognatus) and trout-perch (Percopsis omiscomaycus). Annual growth, estimated from otolith back-calculations, was higher for each of the species in the regulated river relative to the naturally flowing river but did not differ between hydropeaking regimes. Condition was assessed using weight–length relationships and differed between rivers for each species, and between hydropeaking regimes for longnose dace and slimy sculpin. Survival of longnose dace and slimy sculpin was lower in the regulated river relative to the naturally flowing river, but comparable between rivers for trout-perch. Annual growth was significantly related to mean summer discharge in the regulated river and to mean summer water temperature in the naturally flowing river for each species, and significantly different slopes among species indicate species-specific responses to discharge and temperature alterations. This study demonstrates different biological responses among fish species within rivers to regulation in general, as well as to specific hydropeaking regimes. Future studies should focus on multiple species and multiple indicators of fish health to more fully characterize the impacts of river regulation on downstream fish communities. Copyright © 2016 John Wiley & Sons, Ltd.
- Effect of Thermal Stratification on Phytoplankton and Nutrient Dynamics in
a Regulated River (Saar, Germany)
- Authors: F. Engel; H. Fischer
Abstract: The weir pool Serrig is the deepest one along the impounded river Saar. Damming caused massive changes in the river's hydrodynamics. We analyzed the spatio-temporal variability of thermal density stratification in the weir pool and its effect on phytoplankton and nutrient dynamics. In the analysis, continuous measurements from the years 2014 and 2015 were combined with three two-day sampling campaigns in spring 2015. Thermal stratification occurred regularly in the downstream section of the weir pool during spring and summer and showed a diurnal rhythm. Temperature differences >1 K between the 1 and 2 m water layer were observed during 34 out of 217 days (16%) in 2014, with maximum temperature gradients up to 3.71 K. Whereas the influence of thermal stratification on phytoplankton biomass and distribution was low during the algal bloom in early spring, stratification events between May and July promoted temporary algal blooms in the surface layer with chlorophyll a concentrations up to 98 µg Chla l−1 and a maximum difference between the 1 and 2 m water layer of 36 µg Chla l−1. Some of the stratification events resulted in reduced concentrations of dissolved nutrients in the surface layer as a result of increased uptake by algae, with maximum gradients between the surface and the 8 m water layer of 0.070 mg ortho-PO43--P l−1, 0.136 mg NH4+−N l−1 and 0.24 mg NO3¯−N l−1. These vertical gradients should be considered in sampling protocols for the assessment of the water quality of temporarily stratified river sections. Copyright © 2016 John Wiley & Sons, Ltd.
- Flood Inundation Modelling for Mid-Lower Brisbane Estuary
- Authors: X. Liu; S. Lim
Abstract: This study utilizes a two-dimensional hydrodynamic model to calibrate and validate an inundation model for the Brisbane River estuary in Queensland, Australia. The bathymetry data used in the hydraulic model are derived from one arc second (1 s) shuttle radar topography mission digital elevation model, and the two-dimensional hydraulic model is parameterized using the generated bathymetry with four open boundaries with water level observations and roughness coefficients. The calibration performance is evaluated by comparing the simulated results with the digitized records during the January 2013 flood event (a low magnitude event) at three gauging stations. The calibrated model is validated with water level data and available discharge data during the January 2011 flood (a large magnitude event) at four gauging stations located along the Brisbane River. Different performance indices are applied to demonstrate that the developed model performs well during calibration and validation. A sensitivity analysis is presented to assess the influence of riverbed elevation changes on the model because the main uncertainty of the model is the bathymetry data. The proposed model with the shuttle radar topography mission digital elevation model-derived riverbed elevation for the Brisbane estuary is able to predict the flood inundation extent at an accuracy of 66.9% which is higher than or comparable with the accuracies of the existing studies. However, it is expected that the accuracy will increase if some improved bathymetry data become available in the future. Copyright © 2016 John Wiley & Sons, Ltd.
- Socioeconomic Value(s) of Restoring Environmental Flows: Systematic Review
and Guidance for Assessment
- Authors: D. Jorda-Capdevila; B. Rodríguez-Labajos
Abstract: The preservation of instream flows entails multiple benefits not only for river ecosystems but also for human well-being. Benefits of marketed goods and services provided by water withdrawals such as irrigation, water supply and hydropower production are well-known. Others, such as recreational, aesthetic, cultural and existence values of a well-preserved river flows are less studied. There is an increasing interest of policy makers to understand the benefits of costly river ecosystem restoration measures. Moreover, disregarding such benefits may turn into inter-stakeholder conflicts.This paper reviews empirically-based literature assessing environmental flows restoration/conservation. Thus, it offers the state-of-the-art on three aspects: 1) what motivations drive the socioeconomic evaluation of instream flows (policies and alternative instream flow regimes); 2) what values and benefits are associated with instream flows (e.g. the sheer existence of a well-preserved river, productive assets and cultural attributes); and 3) what methods are employed to undertake such assessments (e.g. scenario development, monetary and non-monetary valuations, and stakeholders engagement).Building on this, we propose a methodological framework for case-specific assessments of the restoration of environmental flows. This proposal combines increased stakeholder participation, better understanding of ecosystem functioning, awareness of the plurality of values and an accurate choice of valuation methods. Copyright © 2016 John Wiley & Sons, Ltd.
- Hydrogeochemistry, Isotopic Composition and Water Age in the Hydrologic
System of a Large Catchment within a Plain Humid Environment (Argentine
Pampas): Quequén Grande River, Argentina
- Authors: D. E. Martínez; O. M. Quiroz Londoño, D. K. Solomon, C. Dapeña, H. E. Massone, M. A. Benavente, H. O. Panarello
Abstract: The Quequén Grande River (QGR) is a large catchment (10 000 km2) in the Pampa Plain in Argentina. From November 2004 to April 2013, a hydrochemical and stable isotopes monitoring program was conducted, which included three sampling stations of monthly composite precipitation, weekly samples in two sites along the river and several groundwater samples.A standard data interpretation was initially performed applying standard statistics, Piper diagrams and δ18O versus δ2H diagrams. The time evolution of the values of δ18O in precipitation and streamwater were also determined.The integration of hydrogeochemistry and stable isotopes data indicates the existence of three main components of streamflow: (i) baseflow characterized by electrical conductivity (EC) from 1200 to 1800 µs/cm and an isotope composition quite constant around δ18O −5.3‰ and δ2H −33.8‰. Water age for groundwater contribution is typically around 30 to 40 years using chlorofluorocarbons; (ii) direct runoff composed of channel interception and overland flow, which is of low EC in the order of 50 to 100 µs/cm, and a highly variable isotopic composition; and (iii) translatory flow (pre-event water that is stored within the subsoil) with an intermediate EC and isotopic composition close to that of the weighted average composition of precipitation.The hydrochemical and stable isotopic data allow the differentiation between baseflow and direct runoff. In addition to this, chlorofluorocarbon dating is a useful tool in assessing the dominance of baseflow in a stream. The data lead to a conceptual model in which an intermediate flow system, with mean residence time (MRT) of around 35 years, discharges into the drainage network. A regional flow system (MRT > 50 years) discharges to the ocean. It is concluded that in this large plain catchment streamflow separation, only two components can be applied in: (i) short storm precipitation events having a high sampling frequency and (ii) during long dry periods when pre-event soil water is not released. Copyright © 2016 John Wiley & Sons, Ltd.
- Improving Hydrodynamic Modelling: an Analytical Framework for Assessment
of Two-Dimensional Hydrodynamic Models
- Authors: K. A. Wright; D. H. Goodman, N. A. Som, J. Alvarez, A. Martin, T. B. Hardy
Abstract: Two-dimensional hydrodynamic models are increasingly common in riverine research and management. However, input data are not standardized among studies, and assessments of model performance are uncommon, which hinder interpretation of model results and comparisons among studies. Herein, we describe a framework for two-dimensional hydrodynamic model input data collection, model calibration and validation to evaluate model predictions. We present a logical process for the validation of depth and velocity that recognizes the inherent spatial uncertainty in the field measurements and modelling results. The hydrodynamic model we present as an example shows agreement between predicted and observed water surface elevation, area of inundation and spatial distributions of depth and velocity at calibration and independent validation discharges. If this model development and assessment framework was adopted by others, it would allow comparison between studies and provide a foundation for establishing model performance standards. Copyright © 2016 John Wiley & Sons, Ltd.
- Sediment Pulse Behaviour Following Dam Removal in Gravel-Bed Rivers
- Authors: Kylie Marie Pace; Desiree Tullos, Cara Walter, Stephen Lancaster, Catalina Segura
Abstract: As dams approach the end of their useful life, there is need to predict where and how accumulated sediment will move following dam removal to estimate and mitigate the impacts of this process on aquatic habitat and infrastructure. Flume studies suggest that sediment pulses disperse in place for most dams, but it is hypothesized that certain conditions (e.g., low Froude number, fine pulse grain size, small pulse sizes, and large peak discharge) may characterize pulses that translate downstream. However, quantitative analyses of sediment pulse behavior have not been widely conducted in field settings. We thus analyzed bathymetric data from four field sites in Oregon to investigate the reliability of flume-derived hypotheses (1) whether dispersion or translation dominates across a range of dam removal physiographies using multiple methods of evaluation and (2) if Froude number, pulse material grain size, relative pulse size, and discharge can predict reservoir sediment movement mode. Results indicated that dispersion generally dominated pulse behavior in the field setting, with some limited evidence of translational movement in individual years. The Froude number appeared to be the most reliable for anticipating pulse behavior. Further work is needed to link generalized sediment pulse behavior to sediment mobilization and transport processes. Copyright © 2016 John Wiley & Sons, Ltd.
- Is it Worth the Money? The Functionality of Engineered Shallow Stream
Banks as Habitat for Juvenile Fishes in Heavily Modified Water Bodies
- Authors: J. Pander; M. Mueller, J. Knott, L. Egg, J. Geist
Abstract: Heavily modified water bodies (HMWB) are characterized by monotonous and straightened channel morphologies with high degrees of bank enforcement. They often lack shallow bank habitats, which are considered important for critical life stages of fishes. In this study, three principle options to engineer shallow stream zones were assessed concerning the value of the created habitats for larval, juvenile and adult stages of fishes in 30 sites from three HMWB. The construction scheme of the juvenile habitats comprised different degrees of embankment ranging from rip-rap structures with steep bank angles to almost nature-like construction schemes with very flat river-banks and sparing usage of structural enrichment such as boulders and dead wood. In general, the differences between the three habitat types were more pronounced in density of different life stages than in the presence or absence of species or certain life stages. A steep bank angle and a high degree of engineering such as placement of rip-rap embankment, boulders or dead wood structure in the habitats were hardly accepted by early larval and juvenile stages of rheophilic fishes. In contrast, the construction scheme of a nature-like habitat with a flat bank angle (
- Poor Performance of a Retrofitted Downstream Bypass Revealed by the
Analysis of Approaching Behaviour in Combination with a Trapping System
- Authors: M. Ovidio; A. Dierckx, S. Bunel, L. Grandry, C. Spronck, J.P. Benitez
Abstract: The implementation of fish downstream migration bypass systems is still a major challenge, and there is interest in validating the adequacy of different configurations of bypass devices. In the Amblève River (Belgium), a mobile 3.3-m height dam feeds two principal Francis and one Francis micro-turbine and is equipped with a modern vertical slot fish pass and a downstream bypass. The aim of this study was to test the bypass attraction and efficiency (i.e. percentage of fish that approach the entrance and use the bypass) for Atlantic salmon smolts. During three consecutive years, a total of 1346 smolts were equipped with a radio frequency identification tag and released from March to May upstream of the dam of Lorcé. The entrance of the downstream migration bypass was equipped with a radio frequency identification antenna in order to detect the smolts approaching. In 2014, a capture cage was also placed downstream the bypass to evaluate its efficiency. The mean percentage of detected smolts at the entrance varied from 26.2 to 39.7%. In 2014, 16.5% of the released smolts entered the bypass and were finally caught in the cage, representing 39% of the smolts detected at the entrance. More than 98% of the detections occurred during night (mainly between 9 pm and 3 am). The searching delay near the bypass entrance varied from less than 5 min to more than 5 days (median 4.3 min). Visual observation indicated a behavioural reluctance before entering the bypass, with a shift from positive to negative rheotaxy. Our results underline the difficulty to install retrofitted bypass system on old existing hydropower plants. Copyright © 2016 John Wiley & Sons, Ltd.
- Simulation of Climate Change Effects on Hydropower Operations in Mountain
Headwater Lakes, New Zealand
- Authors: B. S. Caruso; R. King, S. Newton, C. Zammit
Abstract: Future climate change is expected to have wide ranging impacts on the hydrology of mountain rivers because of changes in the magnitudes and timing of rain and snow, as well as the significant spatial variability of topography and other catchment characteristics. In New Zealand, hydropower generation in mountain basins is the primary source of electricity and renewable energy resource in the country. The goal of this study was to simulate and evaluate the potential effects of climate change on hydropower operations in three mountain headwater lakes (lakes Pukaki, Tekapo, and Ohau) in the Upper Waitaki Basin of the central South Island. The TopNet hydrological model was used to estimate catchment runoff and lake inflows based on the 1990s (baseline), 2040s, and 2090s periods. Average temperature and precipitation results from an ensemble of 12 Global Circulation Models based on the IPCC 4th Assessment Report A1B emissions scenario were used as input to TopNet. Linked hydropower lake water balance models were developed and used to simulate hydropower operations including discharge, hydroelectric power generation, and spill based on TopNet future inflow predictions, projected electricity demand, and lake storage and outflow characteristics. Our results indicate that annual lake inflows increase under future climate scenarios, but that there are seasonal effects with increasing flows in winter and early spring, and summer flows decreasing somewhat as a result of increasing temperatures and greater winter rain with less snow. Although overall hydropower generation can increase with the increasing flows and projected electricity demand, the seasonal changes result in demand being met in winter and spring with potential shortfalls in summer and autumn. Maximum annual generation can be achieved for some generating stations, but generation will decrease at other stations and more spill will likely be required through the 2090s because of the seasonal changes. Therefore flood and drought risk could also increase for downstream areas. Results also indicate that by the 2090s electricity demand could exceed generation capacity for these headwater lakes. Copyright © 2016 John Wiley & Sons, Ltd.
- The Effects of Replacing Native Forest on the Quantity and Impacts of
In-Channel Pieces of Large Wood in Chilean Streams
- Authors: L. Mao; F. Ugalde, A. Iroume, S. N. Lacy
Abstract: Dead trees in rivers can significantly affect their morphological and ecological properties by increasing flow resistance, affecting sediment transport, and storing organic matter. Logs are usually recruited from banks or along the entire upstream basin. Although it is generally acknowledged that forested headwater streams feature higher volumes of in-channel pieces of large wood, the influence of forest type and forest management of the potential recruitment zone on the volumes and effects of wood have been less explored, especially in relation to the effects of replacing native forests with pine plantations. This paper presents a comparison of volumes of wood, and characteristics and effects on streams draining paired basins with comparable slopes, areas, and hydrologic regimes, but different in terms of land use. The five selected pairs of basins are located in the Coastal and Andean mountain Ranges in central Chile, in order to compare native forest and pine plantation basins. The results show that logs tend to be shorter and with larger diameters in streams draining native forest basins. Because of their smaller dimensions, logs and jams tend to be more mobile and oriented parallel to the flow. Volumes of in-channel wood in native forest basins are only slightly larger than in pine plantation basins, and no differences have been identified in terms of morphological effects on channel geometry. Also, fish type and biomass were comparable among pairs. Evidence highlights the importance of the width of riparian buffers in mitigating the effects of land use change, especially the substitution of native forest with plantations. Copyright © 2016 John Wiley & Sons, Ltd.
- Benefits of Prescribed Flows for Salmon Smolt Survival Enhancement Vary
Longitudinally in a Highly Managed River System
- Authors: I. I. Courter; T. M. Garrison, T. J. Kock, R. W. Perry, D. B. Child, J. D. Hubble
Abstract: The influence of streamflow on survival of emigrating juvenile Pacific salmonids Oncorhynchus spp. (smolts) is a major concern for water managers throughout the northeast Pacific Rim. However, few studies have quantified flow effects on smolt survival, and available information does not indicate a consistent flow–survival relationship within the typical range of flows under management control. In the Yakima Basin, Washington, the potential effects of streamflow alterations on smolt survival have been debated for over 20 years. Using a series of controlled flow releases from upper basin reservoirs and radiotelemetry, we quantified the relationship between flow and yearling Chinook salmon smolt survival in the 208 km reach between Roza Dam and the Yakima River mouth. A multistate mark–recapture model accounted for weekly variation in flow conditions experienced by tagged fish in four discrete river segments. Smolt survival was significantly associated with streamflow in the Roza Reach [river kilometre (rkm) 208–189] and marginally associated with streamflow in the Sunnyside Reach (rkm 169–77). However, smolt survival was not significantly associated with flow in the Naches and Prosser Reaches (rkm 189–169 and rkm 77–3). This discrepancy indicates potential differences in underlying flow-related survival mechanisms, such as predation or passage impediments. Our results clarify trade-offs between flow augmentation for fisheries enhancement and other beneficial uses, and our study design provides a framework for resolving uncertainties about streamflow effects on migratory fish survival in other river systems. Copyright © 2016 John Wiley & Sons, Ltd.
- Dam Operations Affect Route-specific Passage and Survival of Juvenile
Chinook Salmon at a Main-stem Diversion dam
- Authors: R. W. Perry; T. J. Kock, I. I. Courter, T. M. Garrison, J. D. Hubble, D. B. Child
Abstract: Diversion dams can negatively affect emigrating juvenile salmon populations because fish must pass through the impounded river created by the dam, negotiate a passage route at the dam and then emigrate through a riverine reach that has been affected by reduced river discharge. To quantify the effects of a main-stem diversion dam on juvenile Chinook salmon in the Yakima River, Washington, USA, we used radio telemetry to understand how dam operations and river discharge in the 18-km reach downstream of the dam affected route-specific passage and survival. We found evidence of direct mortality associated with dam passage and indirect mortality associated with migration through the reach below the dam. Survival of fish passing over a surface spill gate (the west gate) was positively related to river discharge, and survival was similar for fish released below the dam, suggesting that passage via this route caused little additional mortality. However, survival of fish that passed under a sub-surface spill gate (the east gate) was considerably lower than survival of fish released downstream of the dam, with the difference in survival decreasing as river discharge increased. The probability of fish passing the dam via three available routes was strongly influenced by dam operations, with passage through the juvenile fish bypass and the east gate increasing with discharge through those routes. By simulating daily passage and route-specific survival, we show that variation in total survival is driven by river discharge and moderated by the proportion of fish passing through low-survival or high-survival passage routes. Copyright © 2016 John Wiley & Sons, Ltd.
- Typology of a Great River Using Fish Assemblages: Implications for the
Bioassessment of the Danube River
- Authors: T. Erős; V. Bammer, Á. I. György, L. Pehlivanov, M. Schabuss, H. Zornig, A. Weiperth, Z. Szalóky
Abstract: Matching habitat typology and ecological assemblages can be useful in environmental management. We examined whether a priori defined riverine sections correspond with distinct fish assemblage types along the >2000 km long course of the Danube River, Europe. We also tested whether different sampling methods (i.e. day and night inshore electric fishing and offshore benthic trawling) provide consistent typological results. Analysis of assemblage similarities, indicator species analysis, non-metric multidimensional scaling (NMDS) and k-means analyses indicated that fish assemblages of the a priori defined Upper-, Middle and Lower-Danubian sections differed slightly, but within class variability was high. Although indicator species analysis showed that the Upper-Danube belongs to the barbel (Barbus barbus) zone and the Middle- and Lower Danube belong to the bream (Abramis spp) zone, indicator values of the character species were generally low. The NMDS analyses suggested a weak gradient in assemblage structure along the course of the river with relatively high variability between neighbouring sites. K-means analyses revealed that many sampling sites were in a different class than the a priori defined sections, and classifications at other group numbers did not lead to better classification outcome. Overall, the results do not suggest clearly distinguishable assemblage types with distinct boundaries in the potamal section of a great river. Nevertheless, the division of the potamon to smaller sections may explain some variability in fish assemblage structure, and could be used for bioassessment purposes. The study also shows the importance of multihabitat and multigear surveys in the typological assessment of great rivers. Copyright © 2016 John Wiley & Sons, Ltd.
- A Statistical Model for Managing Water Temperature in Streams with
- Authors: E. O. McGrath; N. N. Neumann, C. F. Nichol
Abstract: Streams in the Pacific Northwest (Oregon, Washington, British Columbia) face rising summer temperatures and increasing anthropogenic influence, with consequences for fish populations. Guidance is needed in small managed watersheds for setting reservoir release rates or for the restriction of water extractions to meet the needs of fish and aquatic ecosystems. Existing environmental flow methods focus on discharge rates and do not typically consider water temperatures, and detailed thermal models are too complex for widespread implementation. We used multiple logistic regression to develop statistical models for estimating the probability of exceeding a salmonid stream temperature threshold of 22 °C as a function of discharge and maximum daily air temperatures. Data required are air temperature, stream temperature and stream discharge over a minimum of one summer. The models are used to make minimum discharge recommendations under varying forecast weather conditions. The method was applied to nine streams in the Pacific Northwest. Minimum recommended discharge generally ranged from 23% to 86% of mean annual discharge and was higher than observed low flows in most streams. Comparison of the new method to existing methods for Fortune Creek in British Columbia indicated that total season discharge volumes could be reduced while meeting thermal requirements. For other streams, it was evident that high water temperatures cannot be managed by increasing discharge, as the discharge required would be greater than natural discharge and higher than achievable by management. The statistical method described in this paper allows for a risk-based approach to discharge management for fish habitat needs.
- Integrating Hydrological Modelling and Ecosystem Functioning for
Environmental Flows in Climate Change Scenarios in the Zambezi River
(Zambezi Region, Namibia)
- Authors: F. Martínez-Capel; L. García-López, M. Beyer
Abstract: The Zambezi-Chobe wetlands in Namibia are of great international importance for trans-boundary water management because of their remarkable ecological characteristics and the variety and magnitude of the ecosystem services provided. The main objective of this study is to establish the hydro-ecological baseline for the application of environmental flow regimes (EFR). The specific objectives are: (i) the assessment of environmental flow components (EFC) in the current near-natural hydrological conditions; (ii) the generation of future scenarios for climatic and socioeconomic changes; (iii) the estimation of the area–duration curves and estimated annual habitat during the inundation of the critical habitats for fisheries (mulapos), under the existing conditions and future scenarios; and (iv) to provide a framework for the future application of EFRs, based on hydrological and ecological processes. To make a sound analysis of the ecological implications, first we develop a conceptual framework of the linkages between the hydrological and biological processes concerning fish communities, because of the critical role of fisheries in the region. The EFCs in near-natural hydrological conditions provide the basis for developing interim EFRs in the region, within the framework of an adaptive management of water resources. The future scenarios indicate a mitigation of the flow variability; and, in the worst-case scenario, the reduction of the maximum flow and inundated area of the mulapos would result in a reduction of the estimated annual habitat of 22%. This means a reduction in the spawning habitats for quiet-water species, in the food resources for fry and juvenile fish and a consequent reduction in fish stocks. Furthermore, the habitat loss during low events is similar and greater under both scenarios, at ca. 35%. Here we corroborate that the EFCs and their variability may become the building blocks of flow-ecology models that lead to environmental flow recommendations, monitoring and research programmes and flow protection activities. Copyright © 2016 John Wiley & Sons, Ltd.
- Performance of a Vertical-Slot Fish Pass for the Sea Lamprey Petromyzon
marinus L. and Habitat Recolonization
- Authors: E. Pereira; B. R. Quintella, C. S. Mateus, C. M. Alexandre, A. F. Belo, A. Telhado, M. F. Quadrado, P. R. Almeida
Abstract: In 2011, a vertical-slot fish pass was built at the Coimbra Açude-Ponte dam (Mondego River, Portugal), approximately 45 km upstream from the river mouth. The performance of this infrastructure for sea lamprey passage was evaluated between 2011 and 2015 using several complementary methodologies, namely radio telemetry [conventional and electromyogram (EMG)], passive integrated transponder (PIT) telemetry and electrofishing surveys. During the study period, the electrofishing revealed a 29-fold increase in the abundance of larval sea lamprey upstream of the fish pass. Of the 20 radio-tagged individuals released downstream from the dam, 33% managed to find and successfully surpass the obstacle in less than 2 weeks, reaching the spawning areas located in the upstream stretch of the main river and in one important tributary. Fish pass efficiency was assessed with a PIT antenna installed in the last upstream pool and revealed a 31% efficiency, with differences between and within migratory seasons. Time of day and river flow significantly influenced the attraction efficiency of the fish pass, with lampreys negotiating it mainly during the night period and when discharge was below 50 m3 s−1. Sea lampreys tagged with EMG transmitters took 3 h to negotiate the fish pass, during which high muscular effort was only registered during passage, or passage attempts, of the vertical slots. The use of complementary methodologies provided a comprehensive passage evaluation for sea lamprey, a species for which there is a considerable paucity of valuable data concerning behavioural, physiological and environmental influences on obstacle negotiation. Copyright © 2016 John Wiley & Sons, Ltd.
- A Comparison of Main and Side Channel Physical and Water Quality Metrics
and Habitat Complexity in the Middle Mississippi River
- Authors: M. J. Sobotka; Q. E. Phelps
Abstract: Worldwide large rivers have been severely modified by human intervention. Many modifications result in disconnection of the river from floodplain and off-channel habitats generally characterized by lower velocities and Copyright © 2016 John Wiley & Sons, Ltd. shallower depths relative to the main channel, conditions vital to many organisms. Extensive levees on the Middle Mississippi River (MMR) have cut off backwater systems and disconnected the river from 80% of its floodplain. However, the system is characterized by large side channels associated with islands. We examined a long term data set for differences in physical (e.g. depth and velocity) and water quality metrics (e.g. temperature, suspended solids, dissolved oxygen, chlorophyll, % organic matter) between the main and side channels of a 128-km reach of the MMR. We compared variability between main and side channels using the coefficient of variation (COV). All metrics differed between habitats. Side channels were shallower with lower velocities and had greater mean and COV of % organic matter and more variable dissolved oxygen concentrations. Velocity, temperature, and suspended solids were similar in the spring. COVs were lowest in both habitats during the spring for all metrics except temperature and DO. Resource management in the MMR tends to focus on maintaining existing side channels because of the difficulty of working in the heavily used navigation channel. This study shows that these actions protect areas that function differently than the main channel for most of the year. However, our results also highlight the need for restoration activities aimed at restoring floodplain connectivity, especially during the spring. Copyright © 2016 John Wiley & Sons, Ltd.
- Screening the Suitability of Levee Protected Areas for Strategic
Floodplain Reconnection Along the LaGrange Segment of the Illinois River,
- Authors: J. W. F. Remo; R. J. Guida, S. Secchi
Abstract: Levee-protected floodplains along the 125-km LaGrange Segment (LGS) of the Illinois River were screened for their abiotic suitability for alternative ecosystem services (ESs), including wetland creation, habitat, floodwater denitrification and flood-tolerant agriculture. The suitability framework developed for this study builds upon the Land Capability Potential Index and is informed by the current understanding of the linkages between river hydrology, hydraulics, floodplain soils, floodplain vegetation and floodplain nutrient cycling. In addition to screening these floodplain areas for alternative ESs, we demonstrate how this framework can be combined with economic assessments of current floodplain services to inform how strategic floodplain reconnection (i.e. restoration of hydrologic linkages between river and floodplain for the purpose of flood mitigation and provisioning of alternative ESs) could be used to work towards sustainable floodplain management. Results show that ESs increase with upstream distance from the LaGrange Lock and Dam. This is attributed to the operation of the lock and dam generating a water level that would result in the inundation of a substantial portion of floodplain (>70 km2) up to ˜60 km upstream if the levees were to be removed or set back. Comparison of the profits from current floodplain agriculture with the potential profits of flood-tolerant agriculture suggests that overcoming the economic costs of floodplain reconnection within the LGS will likely require both conversion of reconnected floodplain lands to flood-tolerant agriculture and payments for ESs. Copyright © 2016 John Wiley & Sons, Ltd.
- Modelling the Influence of Aquatic Vegetation on the Hydrodynamics of an
Alternative Bank Protection Measure in a Navigable Waterway
- Authors: A. Weber; J. Zhang, A. Nardin, A. Sukhodolov, C. Wolter
Abstract: Computational fluid dynamics (CFD) has become an effective tool for assessing hydrodynamics in complex environments. This paper reports on a CFD study of navigation-induced flows in a shallow, wave-protected, littoral habitat of the urban Spree River. It was constructed as a rehabilitation structure for aquatic organisms and subject to abundant growth of aquatic and riparian vegetation. This study aims to quantify the hydrodynamics induced by vessel movements and its consequences for water exchange and lateral connectivity between the habitat and the main channel with three representative, natural densities of aquatic plants.The simulations revealed both high efficiency of the rehabilitation structure in reducing hydrodynamic forces in the littoral and a superimposed reduction of hydrodynamic forces, and increase of flushing time with increased plant cover. Higher vegetation density resulted in lower wave propagation and lower connectivity of the rehabilitation structure with the fairway. Thus, natural succession of aquatic vegetation in the shallow habitats leads to increasing isolation and finally to terrestrialization. Maintaining the functionality of the rehabilitation structure as habitat for other aquatic organisms requires either plant removal or preferably adaptive modification, e.g. by successively increasing the openings to the main channel and letting the plants take over the protective function of the technical facilities. The developed CFD model helps to find hydrodynamically optimized solutions and to support decision-making process for maintaining littoral refuges for plants and weak swimming organisms in navigable waterways. Copyright © 2016 John Wiley & Sons, Ltd.
- Reducing Carryover Effects on the Migration and Spawning Success of
Sockeye Salmon through a Management Experiment of Dam Flows
- Authors: N. J. Burnett; S. G. Hinch, N. N. Bett, D. C. Braun, M. T. Casselman, S. J. Cooke, A. Gelchu, S. Lingard, C. T. Middleton, V. Minke-Martin, C. F. H. White
Abstract: Effective dam management requires an understanding of the ecological impact of a facility and its operations on individual fish and fish populations. Traversing high flows downstream of dams is an energetically challenging activity that could influence survival and spawning success following passage. Carryover effects, however, are an underappreciated consequence of dam passage that have been overlooked by researchers and natural resource managers. We conducted a large-scale management experiment to determine if the operation of dam attraction flows could be changed to reduce high sockeye salmon Oncorhynchus nerka mortality following passage and increase spawning success. We tested two flow conditions: (i) a baseline condition—currently used by managers—that released high attraction flows directly adjacent to the entrance to a vertical-slot fishway and (ii) an alternative condition that released attraction flows 10 m away from the fishway entrance to reduce the flows fish swim through while approaching the passage structure. We tagged 637 sockeye salmon with telemetry tags to monitor dam passage, post-passage survival to spawning grounds and spawning success under the two flow conditions. Validated fish counters at the exit of the fishway and on spawning grounds were used to generate population level estimates of survival to spawning grounds. Individuals exposed to baseline flow conditions spent two times longer recovering from dam passage and exhibited 10% higher mortality following passage than those exposed to alternative flows. Release of alternative flows for 10 days assisted approximately 550 fish (or 3% of total spawners) in reaching spawning grounds. Once on spawning grounds, female spawning success was strongly influenced by individual spawning characteristics (longevity and date of arrival on spawning grounds) and not dam flow condition. Our findings highlight a cost-effective solution that decreases mortality following passage simply by altering the location of dam flow releases and not reductions in discharge. Copyright © 2016 John Wiley & Sons, Ltd.
- The Accuracy and Reliability of Traditional Surface Flow Type Mapping: Is
it Time for a New Method of Characterizing Physical River Habitat?
- Authors: A. S. Woodget; F. Visser, I. P. Maddock, P. E. Carbonneau
Abstract: Surface flow types (SFTs) are advocated as ecologically relevant hydraulic units, often mapped visually from the bankside to characterize rapidly the physical habitat of rivers. SFT mapping is simple, non-invasive and cost-efficient. However, it is also qualitative, subjective and plagued by difficulties in recording accurately the spatial extent of SFT units. Quantitative validation of the underlying physical habitat parameters is often lacking and does not consistently differentiate between SFTs. Here, we investigate explicitly the accuracy, reliability and statistical separability of traditionally mapped SFTs as indicators of physical habitat, using independent, hydraulic and topographic data collected during three surveys of a c. 50 m reach of the River Arrow, Warwickshire, England. We also explore the potential of a novel remote sensing approach, comprising a small unmanned aerial system (sUAS) and structure-from-motion photogrammetry (SfM), as an alternative method of physical habitat characterization. Our key findings indicate that SFT mapping accuracy is highly variable, with overall mapping accuracy not exceeding 74%. Results from analysis of similarity tests found that strong differences did not exist between all SFT pairs. This leads us to question the suitability of SFTs for characterizing physical habitat for river science and management applications. In contrast, the sUAS–SfM approach provided high resolution, spatially continuous, spatially explicit, quantitative measurements of water depth and point cloud roughness at the microscale (spatial scales ≤1 m). Such data are acquired rapidly, inexpensively and provide new opportunities for examining the heterogeneity of physical habitat over a range of spatial and temporal scales. Whilst continued refinement of the sUAS–SfM approach is required, we propose that this method offers an opportunity to move away from broad, mesoscale classifications of physical habitat (spatial scales 10–100 m) and towards continuous, quantitative measurements of the continuum of hydraulic and geomorphic conditions, which actually exists at the microscale. Copyright © 2016 John Wiley & Sons, Ltd.
- Quantifying Whitewater Recreation Opportunities in Cataract Canyon of the
Colorado River, Utah: Aggregating Acceptable Flows and Hydrologic Data to
Identify Boatable Days
- Authors: E. Stafford; N. Fey, J. J. Vaske
Abstract: The structural norm approach was combined with the Potential for Conflict Index to define recreation streamflow needs for the Colorado River in Utah and Colorado. An online survey was completed by 128 commercial and non-commercial boaters, who evaluated a range of flows for whitewater boating. For the Cataract Canyon reach, respondents rated the quality of their recreation experience of specific flows, describing the quality of boating opportunities across the full range of historical streamflows. Ranges for both acceptable and optimum flows were defined, as well as thresholds for unacceptable flows. These ranges were then evaluated against historical hydrologic records to quantify the timing, frequency, and duration of days when defined whitewater flows exist across different year types (i.e. average boatable days). Results indicated that on average, a total of 257 boatable days existed in dry years, and 353 total boatable days occurred in dry-typical years. In wet and wet-typical years, 362 and 365 total boatable days respectively, occurred on average. Results of the boatable days' analysis indicated that over the 23-year period of record, whitewater boating opportunities occurred nearly every day of the year in all but the driest year types. Results from this study provide resource managers with information which can be used in the development of annual operating plans for the Colorado River Basin and help managers understand how changes in flow impact the quality of recreational opportunities. This application demonstrates the value of analysing boatable days on any river where recreation management is a priority. Copyright © 2016 John Wiley & Sons, Ltd.
- Effect of Proposed Large Dams on Water Flows and Hydropower Production in
the Sekong, Sesan and Srepok Rivers of the Mekong Basin
- Authors: T. Piman; T. A. Cochrane, M. E. Arias
Abstract: Water flow patterns in the Mekong are changing because of on-going rapid hydropower development triggered by economic growth. Of immediate concern are the current and proposed hydropower dams in the transboundary Srepok, Sesan and Srekong (3S) Rivers, which contribute up to 20% of the Mekong's annual flows, have a large potential for energy production and provide critical ecosystem services to the downstream Tonle Sap Lake and Mekong Delta. The objective of this paper is to determine how the operation of the proposed largest individual dams and cascade dam schemes in the 3S Rivers will affect flow regimes and energy production. Daily flows were simulated over 20 years using the Soil and Water Assessment Tool and HEC-ResSim models for a range of dam development and operations scenarios. The development of all dams in the 3S basin under an operation scheme to maximize individual electricity production results in an average 98% increase in dry season flows at the 3S outlet. Over 55% of dry season flows changes are caused by seven proposed large dams, with the Lower Srepok 3 project causing the highest impact. The seven large dams will generate 33.0 GWh/day with a water volume of 17 679 x 106 m3, compared with the current and definite future dams generating 73.2 GWh/day with a much lower volume of 6616 x 106 m3. When a cascade of dams are operational, downstream dams with small reservoirs will produce more energy. However, the marginal increase in energy production from the development of additional dams in the 3S basin will decline rapidly relative to the required water storage increase,. Strategic decision-making on the future of each large proposed dam in the 3S basin needs to be considered by local governments after understanding cumulative operation effects and with further consideration to the potential impact on downstream ecosystem productivity and livelihoods. Copyright © 2016 John Wiley & Sons, Ltd.
- Effects of Oil Palm Plantations on the Habitat Structure and Biota of
Streams in Eastern Amazon
- Authors: L. Juen; E. J. Cunha, F. G. Carvalho, M. C. Ferreira, T. O. Begot, A. L. Andrade, Y. Shimano, H. Leão, P. S. Pompeu, L. F. A. Montag
Abstract: Oil palm plantations have expanded around the world, increasing concern about its pressure on deforestation rates and the homogenization of the landscape. In this context, the present study aimed to evaluate the impact of oil palm plantations on the physical characteristics of streams in Amazonia and their effects on Heteroptera, Odonata and Fish assemblages. A total of 23 streams were sampled, eight within fragments of primary forest, while 15 were in oil palm plantations. Data were collected on characteristics of the channel morphology, substrate, hydraulics, instream cover for aquatic organisms, riparian vegetation, human impacts and woody debris. Instream cover and proximity of human impacts were the variables that had the greatest effects on the physical structure of the streams, showing variation between streams of forest in pristine areas and oil palm plantations. Of the analyzed parameters, substrate, instream cover and woody debris influence the richness of Heteroptera, Odonata and Fish. The impact of oil palm plantations on local streams depended on the size of the plantations, and they cannot be considered an adequate substitute for lost habitats in efforts to preserve the physical habitat of Amazonian streams. Any type of conversion of the natural forest can have direct or indirect impacts on the dynamics and structure of these environments, with potentially negative consequences for their biodiversity. The maintenance of an adequate buffer zone of native riparian vegetation adjacent to the streams that flow through the plantations recommended, because this appears to be the principal factor determining the physical conditions of these streams. Copyright © 2016 John Wiley & Sons, Ltd.
- Understanding the Thermal Regime of Rivers Influenced by Small and Medium
Size Dams in Eastern Canada
- Authors: A. Maheu; A. St-Hilaire, D. Caissie, N. El-Jabi
Abstract: Although small and medium-size dams are prevalent in North America, few studies have described their year-round impacts on the thermal regime of rivers. The objective of this study was to quantify the impacts of two types of dams (run-of-river, storage with shallow reservoirs) on the thermal regime of rivers in eastern Canada. Thermal impacts of dams were assessed (i) for the open water period by evaluating their influence on the annual cycle in daily mean water temperature and residual variability and (ii) for the ice-covered winter period by evaluating their influence on water temperature duration curves. Overall, results showed that the run-of-river dam (with limited storage capacity) did not have a significant effect on the thermal regime of the regulated river. At the two rivers regulated by storage dams with shallow reservoirs (mean depth
- Modelling Temperature, Body Size, Prey Density, and Stream Gradient
Impacts on Longitudinal Patterns of Potential Production of Drift-Feeding
- Authors: J. J. Laliberte; J.R. Post, J.S. Rosenfeld, J.A. Mee
Abstract: In this study, we modelled idealized stream reaches using empirical hydrodynamic and bioenergetic parameters to predict how rainbow trout production depends on physical and biological variations across a downstream gradient, and we compared these downstream effects in a low and high-gradient stream reach. We found that longitudinal production potential (i.e. net rate of energetic intake per 100 m of stream length) generally increased with increasing stream size when stream gradient was low. This was not the case, however, for high-gradient streams, wherein maximum longitudinal production potential was associated with middle or low stream size (QMAD = 2.5 to 25 m3 s−1). Areal production potential (net rate of energetic intake per m2 of wetted stream bed) reached a maximum at low stream size (QMAD = 2.5 m3 s−1) with both high and low gradients. We also showed that high stream temperature and low drift density could potentially cause adult rainbow trout to be excluded from stream reaches with high flow. The models presented here have a stronger mechanistic basis for predicting fish production across heterogeneous stream environments and provide more nuanced predictions in response to variation in environmental features than their physical habitat-based predecessors. Copyright © 2016 John Wiley & Sons, Ltd.
- Stream Temperature Impacts Because of Changes in Air Temperature, Land
Cover and Stream Discharge: Navarro River Watershed, California, USA
- Authors: C. J. Woltemade; T. W. Hawkins
Abstract: Stream temperatures are critically important to aquatic ecology, especially cold-water fish such as salmonids. Stream temperatures are influenced by multiple factors, including local climate, solar radiation on the stream channel, stream discharge volume and groundwater contributions. The Heat Source hydrodynamic and thermodynamic numerical model was used to evaluate temperatures in three stream reaches in the Navarro River watershed, California, USA. The model was calibrated and validated for summer 2015 conditions and then applied to scenarios that address changes in air temperatures, riparian forest cover and stream discharge. Modelling results indicate that stream temperatures are sensitive to changes in air temperatures and riparian forest cover and that higher discharge volume mitigates those impacts. Modelled stream maximum weekly average temperatures (MWAT) increased by 1.5–2.3°C in response to an air temperature increases of 3.5°C under low flow conditions (drought) but by only 0.9–2.0°C under moderate flow. Complete removal of riparian forest in a large-scale forest fire would increase MWAT by 2.2–5.9°C in low discharges and by 1.0–4.4°C under moderate discharge. Riparian zone reforestation would decrease MWATs by less than 0.8°C, a modest change reflecting high existing shade on the modelled stream reaches. Comparison of identical climate and land cover change scenarios under low and moderate discharge conditions reveals that efforts to conserve stream discharge volume could be an effective mechanism to mitigate stream temperature increases. Copyright © 2016 John Wiley & Sons, Ltd.
- City Channel Chironomids—Benthic Diversity in Urban Conditions
- Authors: P. Gadawski; H. W. Riss, M. Płóciennik, E. I. Meyer
Abstract: The study focuses on the diversity of urban channel chironomids (the Aa River, the City of Münster, North-western Germany), initially intended as a proxy of habitat structure. Three ecological key points marked the study:The channel is the discharge effluent of a eutrophic lake.It includes lotic and lentic sections.Runoff variability is high (0.02 to 4 m3 s−2).Chironomid pupal exuviae were sampled from the surface drift. Simultaneously, variable abiotic parameters (runoff, suspensoid contents and weather) were recorded. Samples were taken from September 2011 to April 2012. Communities' diversity (>64 spp.) was relatively high. Data analyses revealed that the most significant drivers of species diversity and abundance were water temperature, suspension, flow velocity, nature nearness, water depth and weather. In addition, the increase of diversity ranged significantly with the quality of suspensoids along the channel course. Considering the great complexity of ecological interrelations found on a limited physical scale, the potential of chironomids as sentinel organisms shall be discussed critically. Ongoing analyses focus on the specification of fine particulate organic matter, microhabitat structure and microhydraulics for the development of chironomid communities.
- Downstream Regime Relations for Single-Thread Channels
- Authors: J. B. Thayer
Abstract: New empirically derived downstream hydraulic geometry relations are developed for single-thread gravel/cobble-bed and sand-bed channels using the independent variables bankfull discharge, channel slope, and median bed grain size. Differences in channel response to the controlling variables are observed between gravel/cobble-bed and sand-bed channels. It is found that the inclusion of channel slope into regime relations is necessary for accurate channel geometry predictions and that bed grain size becomes an unnecessary variable. Accuracy of predictions is superior to many existing relations and comparable with those that already include slope as an independent variable. Variability of prediction errors is comparable with existing relations. Applications and implications of the new relations are discussed. Copyright © 2016 John Wiley & Sons, Ltd.
- Temporal and Spatial Variation in Riparian Vegetation and Floodplain
Aquifers on the Regulated Dolores River, Southwest Colorado, USA
- Authors: C. E. Dott; G. L. Gianniny, M. J. Clutter, C. Aanes
Abstract: The importance of flow variability and floodplain water table recharge for the establishment and long-term survival of riparian vegetation has been well-documented. However, temporal and spatial variation in floodplain aquifers has received less attention, although native species can have narrow tolerances for groundwater decline. Our observations of decreased cottonwood cover on floodplains and increased willow cover on river banks since dam completion on the Dolores River led to comparisons between three long-term study sites above and below McPhee Dam. We summarize 5 years (2010–2014) of shallow groundwater well data from transects of three wells per site. Vegetation cover data were collected from quadrats and line-intercept transects. In the willow zone, groundwater well levels mirror in-channel flows and rarely drop below 0.6 m from ground surface. Willow cover and stem counts on point bars are higher at dammed sites. Wells in the cottonwood zone indicate that alluvial recharge happens only during prolonged peak discharge during spring snowmelt or dam release. Years with no dam spill reduced connectivity between surface flows and groundwater, and groundwater depth dropped to between 2 and >2.5 m. Long-term data below the dam indicate that canopy cover of the dominant cottonwoods has declined over time (48% in 1995, 19% in 2003), especially in the wake of severe drought. Mature cottonwood cover is significantly higher at the undammed site (p = 0.025). Our results indicate that floodplain habitats below dams exist under artificially extreme drought and inform how biologically diverse riparian systems will be impacted by a drying climate. Copyright © 2016 John Wiley & Sons, Ltd.
- Hydraulic and Physical Structure of Runs and Glides Following Stream
- Authors: S. Abel; L. C. Hopkinson, W. C. Hession
Abstract: Hydraulic units are often linked to ecological habitat through geomorphic structure, and a better understanding of the turbulent characteristics of the units is needed. Our work examined the near-bed turbulent structure of runs and glides in a restored river and investigated the physical characteristics that influenced the near-bed hydraulics in these units. The research was completed in three restored reaches and one reference reach at the Virginia Tech Stream Research, Education, and Management Laboratory. The laboratory is unique because three different restoration treatments were applied contiguously along a stream, and the restoration practices ranged from passive to active. The passive reach included cattle exclusion, while the active reaches included cattle exclusion as well as vegetation plantings, bank sloping and the construction of inset floodplains. Three-dimensional velocities were measured near the channel bed in run and glide biotopes within the three restored reaches, as well as an upstream reference reach. The velocities were utilized to analyse and compare near-bed turbulent structure across the reaches. While the restoration activities did not address the channel bed directly, differences in physical structure of the two physical biotopes were observed among restoration treatments, likely because of changes in bank shape and roughness due to vegetation differences. Differences between reference and restored reaches were still evident approximately 3 years after cattle exclusion and construction activities. Few differences were observed in the hydraulic structure between runs and glides, and the near-bed flow structure in both runs and glides was related to local roughness. Copyright © 2016 John Wiley & Sons, Ltd.
- Multi-scale Approach to Hydrological Classification Provides Insight to
Flow Structure in Altered River System
- Authors: J. J. Spurgeon; M. A. Pegg, M. J. Hamel
Abstract: Rivers are hierarchical systems exhibiting processes and patterns across spatial and temporal scales principally driven by changes in flow. Hydrological indices estimated with mean or median daily flow data (i.e. daily scale) may be insensitive to anthropogenic alteration that imparts sub-daily variation to flow. Therefore, indices developed at multiple temporal resolutions may provide additional insight into the presence of flow patterns masked by traditional techniques. We characterized the flow regime along the longitudinal gradient of the Platte River, a large Great Plains USA river, using hydrological indices derived with mean daily and sub-daily flow data and a combination of multivariate statistical techniques. Three unique flow units were evident using daily scale flow data, whereas six unique flow units were evident at the sub-daily scale. Flow units at both scales were not static, but rather the presence and extent of flow units across the riverscape depended on climate, tributary inflows and human influence. Anthropogenic alteration including hydropeaking was evident at the sub-daily scale but not at the daily scale. The full complement of flow structure within regulated rivers, therefore, may not be captured using mean or median daily discharge values alone. Inductive river classification studies may benefit from assessing hydrological indices at multiple scales, particularly when investigating river systems with anthropogenic modification such as hydropeaking. Copyright © 2016 John Wiley & Sons, Ltd.
- Coupled Hydrological/Hydraulic Modelling of River Restoration Impacts and
- Authors: H. M. Clilverd; J. R. Thompson, C. M. Heppell, C. D. Sayer, J. C. Axmacher
Abstract: Channelization and embankment of rivers has led to major ecological degradation of aquatic habitats worldwide. River restoration can be used to restore favourable hydrological conditions for target species or processes. However, the effects of river restoration on hydraulic and hydrological processes are complex and are often difficult to determine because of the long-term monitoring required before and after restoration works. Our study is based on rarely available, detailed pre-restoration and post-restoration hydrological data collected from a wet grassland meadow in Norfolk, UK, and provides important insights into the hydrological effects of river restoration. Groundwater hydrology and climate were monitored from 2007 to 2010. Based on our data, we developed coupled hydrological/hydraulic models of pre-embankment and post-embankment conditions using the MIKE-SHE/MIKE 11 system. Simulated groundwater levels compared well with observed groundwater. Removal of the river embankments resulted in widespread floodplain inundation at high river flows (>1.7 m3 s−1) and frequent localized flooding at the river edge during smaller events (>0.6 m3 s−1). Subsequently, groundwater levels were higher and subsurface storage was greater. The restoration had a moderate effect on flood peak attenuation and improved free drainage to the river. Our results suggest that embankment removal can increase river–floodplain hydrological connectivity to form a more natural wetland ecotone, driven by frequent localized flood disturbance. This has important implications for the planning and management of river restoration projects that aim to enhance floodwater storage, floodplain species composition and biogeochemical cycling of nutrients. © 2016 The
Authors . River Research and Applications Published by John Wiley & Sons Ltd.
- Hydropower Development, Riverine Connectivity, and Non-sport Fish Species:
criteria for Hydraulic Design of Fishways
- Authors: A. Laborde; A. González, C. Sanhueza, P. Arriagada, M. Wilkes, E. Habit, O. Link
Abstract: Hydropower barriers are among the most conspicuous anthropogenic alterations to natural riverine connectivity, resulting in species-specific effects linked to dispersal abilities, especially swimming performance. They may present a particular problem for small-bodied ‘non-sport fish’, such as those that characterize the freshwater communities of temperate regions in the Southern Hemisphere. Recent studies have suggested that nature-like fishways could ensure passage of diverse fish assemblages through hydropower barriers. Through experiments performed in a swim tunnel, we present, for the first time, fishway design criteria for two non-sport species endemic to Chile, a country experiencing rapid hydropower development. In`cremental velocity tests showed that Cheirodon galusdae and juveniles of Basilichthys microlepidotus were capable of very similar standardized critical swimming speeds of 69.7 and 69.6 cm s−1, respectively. When expressed in units of body lengths, C. galusdae was capable of very high critical speeds of 16.2 bl s−1, whereas for B. microlepidotus, this was 7.6 bl s−1. However, fixed velocity tests revealed that the swimming endurance of the latter species was slightly higher. Dimensionless analysis showed a clear relationship between fatigue time and fish Froude number, similar to that already described for subcarangiforms. Based on these results, we present fishway design curves indicating a transition from sustained to prolonged swimming at a fishway length of 15 m. Our results show that the swimming capacity of these species is well-suited to the mean flow velocity field described for nature-like fishways. However, more work is required to understand the effects of turbulence on the passage of non-sport species. Copyright © 2016 John Wiley & Sons, Ltd.
- Assessment of the Entering Stock, Migration Dynamics and Fish Pass
Fidelity of European Eel in the Belgian Meuse River
- Authors: B. Nzau Matondo; J. P. Benitez, A. Dierckx, J. C. Philippart, M. Ovidio
Abstract: Migration dynamics of incoming eels in Belgium via Lixhe in the Meuse River were investigated using two fish passes with different configurations—net traps and automatic detection stations—as tools to distinguish resident and migrating eels. From April to September 2013, 435 eels (P50 length, 403 mm; range, 196–836 mm) were caught (daily maxima catch, 90 eels per day), 90% between 13 June and 1 August (50 days) and P50 on 19 July. Eels migrated mostly at 19–26 °C (P50, 24.4 °C), river discharge 65–314 m3 s−1 (P50, 84 m3 s−1), during the dark at 00:00–05:00 h and during both the waxing and waning phases of moonlight. From 396 eels tagged and released 0.3 km downstream of the Lixhe dam, 6.8% of them were recaptured, and 37.4% were detected. Migration flux was estimated at 7184 eels (0.863 t) using the mark-recapture method and decreased to 1156 eels (0.139 t) using automatic transponder detection. Most eels probably migrated through a sluice located downstream of Lixhe to reach the upper Meuse via the Albert Canal. Eels moved almost independently to the configuration of the fish passes and their location, but most eels displayed fidelity to the fish pass where they were captured. Migrant eels showed a wide range of size and life stages, with a higher proportion of eels (80%) belonging to the yellow eel stage. A lower proportion of eels (6%) had a larger size and presented an advanced continental silvering process corresponding to the migrating stage before their transatlantic migration. Copyright © 2016 John Wiley & Sons, Ltd.
- Fluvial Corridor Changes Over Time in Regulated and Non-Regulated Rivers
(Upper Esla River, NW Spain)
- Authors: V Martínez-Fernández; M González del Tánago, J Maroto, D. García de Jalón
Abstract: Over the last decades, rivers and fluvial corridors have been noticeably modified from their natural conditions. In general, damming and other in-channel human interventions have been traditionally considered as the main drivers of change. However, recent studies highlight the influence of climate, hillslope and floodplain cover changes over fluvial corridor dynamics. The present study illustrates the channel morphology and riparian vegetation responses observed in three gravel bed rivers located in the Upper Esla River, north-west of Spain. The entire study catchment was exposed to afforestation changes and farmland abandonment during the last decades, and two of the rivers are regulated by large dams. Analysis of historical orthophotos at different periods between 1956 and 2011 allowed quantifying channel narrowing, reduction of braiding index and vegetation encroachment along the three rivers. Field reconnaissance of landforms and vegetation structure along transects showed significant differences in species composition and age structure between the non-regulated reach, where recruitment of Salicacea pioneer species existed, and the regulated reaches where mature and late-seral species were much more abundant. These responses were consistent with reductions in mean annual discharge in all rivers and with flood disturbance decrease and summer minimum flow increase that were observed in the regulated rivers. Copyright © 2016 John Wiley & Sons, Ltd.
- Informing Watershed Connectivity Barrier Prioritization Decisions: A
- Authors: S. K. McKay; A. R. Cooper, M. W. Diebel, D. Elkins, G. Oldford, C. Roghair, D. Wieferich
Abstract: Water resources and transportation infrastructure such as dams and culverts provide countless socio-economic benefits; however, this infrastructure can also disconnect the movement of organisms, sediment, and water through river ecosystems. Trade-offs associated with these competing costs and benefits occur globally, with applications in barrier addition (e.g. dam and road construction), reengineering (e.g. culvert repair), and removal (e.g. dam removal and aging infrastructure). Barrier prioritization provides a unique opportunity to: (i) restore and reconnect potentially large habitat patches quickly and effectively and (ii) avoid impacts prior to occurrence in line with the mitigation hierarchy (i.e. avoid then minimize then mitigate). This paper synthesizes 46 watershed-scale barrier planning studies and presents a procedure to guide barrier prioritization associated with connectivity for aquatic organisms. We focus on practical issues informing prioritization studies such as available data sets, methods, techniques, and tools. We conclude with a discussion of emerging trends and issues in barrier prioritization and key opportunities for enhancing the body of knowledge. Copyright © 2016 John Wiley & Sons, Ltd.
- Issue Information - TOC
- Pages: 1825 - 1825
Abstract: No abstract is available for this article.
- Issue Information - Info Page
- Pages: 1826 - 1826
Abstract: No abstract is available for this article.
- Potential Effects of Climate Change on Ecologically Relevant Streamflow
- Authors: S. Dhungel; D. G. Tarboton, J. Jin, C. P. Hawkins
Pages: 1827 - 1840
Abstract: We assessed the climate-driven changes in ecologically relevant flow regimes expected to occur by the year 2100 in streams across the conterminous United States. We used long-term daily flow measurements from 601 gauged streams whose watersheds were in relatively natural condition to characterize spatial variation in 16 flow regime variables selected for their ecological importance. Principal component analysis of these 16 variables produced five uncorrelated factors that described patterns of spatial covariation in flow regimes. These five factors were associated with low flow, magnitude, flashiness, timing, and constancy characteristics of the daily flow regime. We applied hierarchical clustering to the five flow factors to classify the 601 streams into three coarses and eight more finely resolved flow regime classes. We then developed a random forest model that used watershed and climate attributes to predict the probabilities that streams belonged to each of the eight finely resolved flow regime classes. The model had a prediction accuracy (per cent correct classification) of 75%. We used the random forest model with downscaled climate (precipitation and temperature) projections to predict site-specific changes in flow regime classes expected by 2100. Thirty-three per cent of the 601 sites were predicted to change to a different flow regime class by 2100. Snow-fed streams in the western USA were predicted to be less likely to change regimes, whereas both small, perennial, rain-fed streams and intermittent streams in the central and eastern USA were predicted to be most likely to change regime. Copyright © 2016 John Wiley & Sons, Ltd.
- Future Water Supply and Demand Management Options in the Athabasca Oil
- Authors: D. Leong; S. Donner
Pages: 1853 - 1861
Abstract: The Athabasca River Basin, home to Canada's growing oil sands mining industry, faces challenging trade-offs between energy production and water security. Water demand from the oil sands mining industry is projected to increase as climate change is projected to alter the seasonal freshwater supply. In this study, a range of water management options are developed to investigate the potential trade-offs between the scale of bitumen production and industry growth, water storage requirements, and environmental protection for the aquatic ecosystems, under projections of mid-century climate change. It is projected that water storage will be required to supplement river withdrawals to maintain continuous bitumen production under the impacts of future climate warming. If high growth in future bitumen production and water demand is the priority, then building sufficient water storage capacity to meet industry demand will be comparable to a week of lost revenue because of interrupted production. If environmental protection is prioritized instead, it will require over nine times the water storage costs to maintain water demand under a high industry growth trajectory. Future water use decisions will need to first, determine the scale of industry and environmental protection, and second, balance the costs of water storage against lost revenue because of water shortages that limit bitumen production. This physically based assessment of future water trade-offs can inform water policy, water management decisions, and climate change adaptation plans, with applicability to other regions facing trade-offs between industrial development and ecosystem water needs. Copyright © 2016 John Wiley & Sons, Ltd.
- Historical Changes of Hydrological Connectivity of Selected Polish
- Authors: J. Dawidek; B. Ferencz
Pages: 1862 - 1871
Abstract: The main ecological and hydrological features of floodplain lakes (FPL) depend on the flood pulse. Temporal variations of connectivity result from natural fluctuations in a parent river water levels. The study area was a fragment of left fraction of the Bug River valley, within a gorge-like section between Dorohusk and Włodawa. The aim of the study was to define a duration and frequency of potamophases and limnophases of 20 FPLs, during the period 1952–2013. A large variation of limnophase frequency was observed. The most frequently occurs short (8–30 days) and medium-length (183–365 days) limnophases. In case of potamophases the most frequent were short episodes (8–30 days). In most water bodies, a general similarity of the duration of functional periods was observed. The average ratio of the duration of both phases showed prevalence of limnophases. Generally, two factors were observed that shape variability of functional periods in the study area: quantity of water input and FPL morphometry. The lower lake volume and less stable water input, the higher variability of hydrological connectivity. Copyright © 2016 John Wiley & Sons, Ltd.
- Lethal Thermal Maxima for Age-0 Pallid and Shovelnose Sturgeon:
Implications for Shallow Water Habitat Restoration
- Authors: D. Deslauriers; L. Heironimus, S. R. Chipps
Pages: 1872 - 1878
Abstract: We evaluated temperature tolerance in age-0 pallid and shovelnose sturgeon (Scaphirhynchus albus and Scaphirhynchus platorynchus), two species that occur sympatrically in the Missouri and Mississippi Rivers. Fish (0.04–18 g) were acclimated to water temperatures of 13, 18 or 24 °C to quantify temperatures associated with lethal thermal maxima (LTM). The results show that no difference in thermal tolerance existed between the two sturgeon species, but that LTM was significantly related to body mass and acclimation temperature. Multiple linear regression analysis was used to estimate LTM, and outputs from the model were compared with water temperatures measured in the shallow water habitat (SWH) of the Missouri River. Observed SWH temperatures were not found to yield LTM conditions. The model developed here is to serve as a general guideline in the development of future SWH. Copyright © 2016 John Wiley & Sons, Ltd.
- Downstream Passage of Fish Larvae at the Salto Grande Dam on the Uruguay
- Authors: C. M. Fuentes; M. I. Gómez, D. R. Brown, A. Arcelus, A. Espinach Ros
Pages: 1879 - 1889
Abstract: We evaluated the passage of early-stage fishes through the Salto Grande Dam using high-frequency downstream ichthyoplankton monitoring and five surveys involving samples taken upstream and downstream of the dam. Eggs and larvae of migratory fishes were captured downstream of the dam, usually during high discharges. Upstream and downstream larvae were frequently unyolked, which corresponds to individuals aged 4+ days, and represents a time significantly longer than that required for the displacement of the water mass from the dam to the sampling location. In low flow rate surveys, fish larvae of the same species and degree of development were captured immediately upstream and at 1, 10, 24 and 40 km downstream of the dam. The densities and percentage of Pimelodinae larvae captured alive by short time and low speed tows were similar upstream and downstream of the dam, indicating that larval mortality was a result of sampling and not to the passage through the turbines. The results show that the larvae of fish that spawn in the middle section are partly transported to the lower section, and suggest that both spillway and turbine discharge should be considered part of the passage. We also found evidence that the passage of small and fragile Pimelodinae larvae through the Salto Grande Kaplan turbines does not significantly affect survival rates. Copyright © 2016 John Wiley & Sons, Ltd.
- Patchiness in a Large Floodplain River: Associations Among Hydrology,
Nutrients, and Fish Communities
- Authors: N. R. De Jager; J. N. Houser
Pages: 1915 - 1926
Abstract: Large floodplain rivers have internal structures shaped by directions and rates of water movement. In a previous study, we showed that spatial variation in local current velocities and degrees of hydrological exchange creates a patch-work mosaic of nitrogen and phosphorus concentrations and ratios in the Upper Mississippi River. Here, we used long-term fish and limnological data sets to test the hypothesis that fish communities differ between the previously identified patches defined by high or low nitrogen to phosphorus ratios (TN:TP) and to determine the extent to which select limnological covariates might explain those differences. Species considered as habitat generalists were common in both patch types but were at least 2 times as abundant in low TN:TP patches. Dominance by these species resulted in lower diversity in low TN:TP patches, whereas an increased relative abundance of a number of rheophilic (flow-dependent) species resulted in higher diversity and a more even species distribution in high TN:TP patches. Of the limnological variables considered, the strongest predictor of fish species assemblage and diversity was water flow velocity, indicating that spatial patterns in water-mediated connectivity may act as the main driver of both local nutrient concentrations and fish community composition in these reaches. The coupling among hydrology, biogeochemistry, and biodiversity in these river reaches suggests that landscape-scale restoration projects that manipulate hydrogeomorphic patterns may also modify the spatial mosaic of nutrients and fish communities. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
- Effects of Land Use on the Composition and Structure of Aquatic
Invertebrate Community and Leaf Breakdown Process in Neotropical Streams
- Authors: T. J. Malacarne; M. T. Baumgartner, Y. Moretto, É. A. Gubiani
Pages: 1958 - 1967
Abstract: Different land uses directly affect the characteristics of a river basin and influence the aquatic biota and ecosystem processes. This study aimed to analyse the community structure and composition of aquatic invertebrates and the role of these organisms in the process of leaf litter breakdown in streams with different land uses. The study was conducted from September to December 2013 in five streams in the Neotropical region. At each stream, we placed 18 bags containing litter for colonization by aquatic invertebrates, and the bags were collected at different exposure times (5, 30, 45, 60, 75 and 90 days). We registered spatial differences in the aquatic invertebrate community structure and composition. There were no significant differences in the activity of invertebrates in the leaf litter breakdown process among streams with different land uses. However, the variability in mass decay rate was lower for the reference stream. This result may have been influenced by habitat quality, availability of organic matter and the structure and composition of benthic community present in the reference stream, which differs significantly among locations with different types of land use. The results of this study shows that human activities, particularly agriculture and urbanization, modify the structure and composition of the benthic community and acts on ecosystem processes, especially in the variability of the processing of allochthonous material invertebrates. However, we reject the hypothesis that land use negatively influences the decomposition of litter, measured by weight loss. Copyright © 2016 John Wiley & Sons, Ltd.
- Impact of Incision of Gravel-bed Rivers on Ground Beetle Assemblages
- Authors: T. Skalski; R. Kędzior, B. Wyżga, A. Radecki-Pawlik, K. Plesiński, J. Zawiejska
Pages: 1968 - 1977
Abstract: The impact of river incision induced by channelization and gravel mining on the structure of ground beetle assemblages in riparian habitats was investigated on three montane rivers in southern Poland. Ground beetles were collected on three benches of different elevation in 11 incised and 14 vertically stable cross sections of the rivers. In total, 5821 individuals representing 106 species were collected. The effect of river incision on the diversity and abundance of ground beetles depended on bench height. Only on the lowest bench, inundated about once per year on average, species richness of the assemblages was significantly reduced in incised river cross sections. On this bench, the abundance of the specialists of exposed riverine sediments, i.e. small and medium-sized predators with high dispersal power and spring breeding strategy, was highly negatively affected by river incision. On the highest bench, large, brachypterous species with spring and autumn breeding strategy, typical of undisturbed habitats, were more abundant in incised cross sections. As this bench is practically not subjected to flooding even in vertically stable cross sections, these species probably benefited from the occurrence of riparian forest along most incised river sections, whereas the riparian areas along vertically stable sections are subjected to higher agricultural pressure. This study shows that in the mountain region where high precipitation helps to maintain moisture of the riparian habitats, river incision has a negative impact only on the specialists of exposed riverine sediments. Copyright © 2016 John Wiley & Sons, Ltd.
- Abiotic Characterization of Brown Trout (Salmo trutta f. fario) and
Rainbow Trout (Oncorhynchus mykiss) Spawning Redds Affected by Small
Hydropower Plants — Case Studies from Austria
- Authors: W. Obruca; C. Hauer
Pages: 1989 - 1995
Abstract: Salmonid rivers in Austria are considerably regulated by small hydropower facilities, resulting in potential declines of the spawning habitats of salmonids. To assess the restrictions and possible quality of hydropower-influenced river sections for salmonid, spawning redd densities of brown trout and rainbow trout were monitored in two rivers in 2014 and 2015. The results showed spawning close to small hydropower facilities for both investigated species — with similarities in redd characteristics like pit and tail length. Differences occurred concerning the distance of redd construction to the next shore. Brown trout spawn close to the banks in comparison to rainbow trout which use the entire active channel width. In addition to the preference of brown trout for certain cover types, it turned out that the presence of high quality spawning gravel in the river is the dictating abiotic variable (probably bottleneck) in the control of salmonid populations even for river reaches impacted by small hydropower plants. Moreover, the assessments of spawning redd densities enabled a discussion of different opportunities for spawning habitat enhancement of salmonids in river sections regulated by small hydropower facilities. Here, in conclusion, it was found that the fill-up of the backwater sites by transported sediments or the structural modification (e.g. boulder placement) in the tail of the backwater could improve the spawning situation in a sustainable way. Copyright © 2016 John Wiley & Sons, Ltd.