- A Conceptual Model of Vegetation–hydrogeomorphology Interactions
Within River Corridors
- Authors: A. M. Gurnell; D. Corenblit, D. García de Jalón, M. González del Tánago, R. C. Grabowski, M. T. O'Hare, M. Szewczyk
Abstract: We propose a conceptual model of vegetation–hydrogeomorphology interactions and feedbacks within river corridors (i.e. river channels and their floodplains) that builds on previous similar hydrogeomorphologically centred models by
incorporating hydrogeomorphological constraints on river corridor vegetation from region to reach scales;
defining five dynamic river corridor zones within which different hydrogeomorphological processes are dominant so that plants and physical processes interact in different ways, and considering the potential distribution of these zones longitudinally from river headwaters to mouth, laterally across the river corridor, and in relation to different river planform styles;
considering the way in which vegetation‐related landforms within each zone may reflect processes of self‐organization and the role of particular plant species as physical ecosystem engineers within the context of the dominant hydrogeomorphological processes;
focussing, in particular, upon a ‘critical zone’ at the leading edge of plant–hydrogeomorphological process interactions that is located somewhere within the area of the river corridor perennially inundated by flowing water (zone 1) and the area that is frequently inundated and subject to both sediment erosion and deposition processes (zone 2). Within the critical zone some plant species strongly influence the position and character of the margin between the river channel and floodplain, affecting channel width, channel margin form and dynamics, and the transition from one river planform type to another; and
considering the vegetated pioneer landforms that develop within the critical zone and how their morphological impact needs to be scaled to the river size.
The model is illustrated using three example reaches from rivers within different biogeographical zones of Europe, and its potential application in the context of river management and restoration/rehabilitation is discussed. Copyright © 2015 John Wiley & Sons, Ltd.
- Fish Assemblage and Ecosystem Metabolism Responses to Reconnection of the
Bird's Point‐New Madrid Floodway during the 2011 Mississippi River
- Authors: H. Rantala; D. Glover, J. Garvey, Q. Phelps, S. Tripp, D. Herzog, R. Hrabik, J. Crites, M. Whiles
Abstract: Understanding the ecological function of developed large rivers remains elusive because these systems have long been altered for multiple uses. In particular, floodplains of large rivers, such as the Mississippi River, have been contained behind extensive levees. A historic flood occurred in the lower Mississippi River system during spring of 2011, prompting the US Army Corps of Engineers to activate the Bird's Point‐New Madrid floodway, a 55 000‐ha, agriculturally dominated, leveed area. Water entered the floodway at flows >1 m s−1 through two crevasses created in the upper portion of the levee and exited through a crevasse at the lower end. During the month, the floodway was inundated; we quantified discharge, water chemistry, primary production and fish production in the floodway and the adjacent river. Water entering the floodway was retained
- Pulsed Flow Wave Attenuation on a Regulated Montane River
- Authors: C. Fong; S. Yarnell, J. Viers
Abstract: This study investigated the effects of hydrograph shape on attenuation of regulated pulsed flow events below a hydropower dam by categorizing and modelling the downstream movement of representative pulses on the upper Tuolumne River in the Sierra Nevadas of California, USA. We extracted underlying hydrograph shape patterns using principal component analysis on individual pulsed flow events released from 1988 to 2012 (n = 4439). From principal component loadings, six shape categories were determined: rectangular, front‐step, back‐step, goalpost, centred tower, and other. Attenuation of representative pulses from each shape type was then modelled using a one‐dimensional hydraulic model of 42 river km. Model results demonstrated a durational threshold for representative pulses (~3–5 h) over which the degree of attenuation of ramping rates and peak discharge approached a limit. Simulations of front and back‐step representative pulses showed trade‐offs between attenuation of peak magnitudes and steepness of rising ramping rates. Reshaping pulses to reduce the adverse ecological effects of rapid changes in stage and velocity downstream was infeasible if the system was required to maintain current electricity production and recreational service levels. Copyright © 2015 John Wiley & Sons, Ltd.
- Modelling Whitewater Park Hydraulics and Fish Habitat in Colorado
- Authors: E. Kolden; B. D. Fox, B. P. Bledsoe, M. C. Kondratieff
Abstract: Whitewater parks (WWPs) are increasingly popular recreational amenities, but the effects of WWPs on fish habitat and passage are poorly understood. This study investigated the use of a two‐dimensional (2‐D) model as compared with a three‐dimensional (3‐D) hydrodynamic model (flow‐3D®) for assessing effects of WWPs on fish habitat. The primary aims of this study were to (1) examine the utility of 3‐D modelling versus 2‐D modelling in a hydraulically complex WWP and (2) compare modelled habitat quality for resident fishes with actual fish abundance and biomass generated from field sampling surveys. Two reaches of a wadeable river in Colorado were modelled: a natural reach and a reach containing a WWP. A 2‐D habitat suitability analysis for juvenile and adult brown trout, juvenile and adult rainbow trout, longnose dace and longnose sucker predicted the same or higher habitat quality in the WWPs than the natural pools for all four species and for all modelled flow rates; however, results from fish sampling found significantly higher fish biomass for all four species in natural pools compared with WWP pools. All hydraulic metrics (depth, depth‐averaged velocity, turbulent kinetic energy, 2‐D and 3‐D vorticity) had higher magnitudes in WWP pools than in natural pools. In the WWP pools, 3‐D model results described the spatial distribution of flow characteristics or the magnitude of variables better than 2‐D results. This supports the use of 3‐D modelling for complex flows found in WWPs, but improved understanding of linkages between fish habitat quality and 3‐D hydraulic descriptors is needed. Copyright © 2015 John Wiley & Sons, Ltd.
- Implications of Genome Alterations in Chironomus bernensis Klȍtzli
- Authors: P. Michailova; J. Ilkova, K. White
Abstract: This study assesses the effect of sediment contaminants as indicated by the measurement of trace metal levels in two large Bulgarian rivers (river Maritsa and a tributary and the river Chaya) on the genome of the abundant chironomid species Chironomus bernensis Klȍtzli. Six trace metals: Cd, Cr, Cu, Mn, Pb and Zn were analysed in the sediments plus the overlying water. The polytene chromosomes of C. bernensis were very sensitive to the pollutants on the basis of numerous somatic chromosome alterations. Two biomarkers based on the degree of somatic structural chromosome alterations—the somatic and cytogenetic indices were applied. Both indices are a sensitive and reproducible approach for assessing the genotoxic effect of contaminants in the sediments. The somatic index from the differentially contaminated sites varied from 1.93 to 2.61, indicating the sensitivity of the C. bernensis genome to anthropogenic stress. The cytogenetic index revealed a high level of pollution in the rivers with a score between 0.27 and 0.37 (
- Vegetation–Hydrogeomorphology Interactions in a Low‐Energy,
- Authors: A. M. Gurnell; R. C. Grabowski
Abstract: The geomorphological dynamics of rivers have been traditionally explained largely by the physical processes of water flow, and sediment erosion and deposition, but the significant role of a third element, vegetation, in driving geomorphological changes has been increasingly highlighted recently. However, few studies have documented how both aquatic and woody riparian plants interact with fluvial processes to induce landform development and initiate channel adjustment. This paper presents analyses of historical maps, recent aerial images and field observations from the River Frome (Dorset, UK), which, as a result of human pressures, has been subject to an increased supply of sand and finer sediment, particularly over the last 50–60 years. Analysis of these information sources indicates that this low‐energy river has adjusted to this delivery of finer sediment by narrowing and increasing its sinuosity. The analysis also indicates that this has been achieved through interactions amongst vegetation, water flow and sediment. Emergent aquatic macrophytes were observed to retain sediment, which leads to the development of submerged shelves that aggrade and become colonized by other plant species to form bars, berms and benches, eventually leading to the extension of river banks into the channel and also the formation of islands. Where woody riparian vegetation is well developed, complex geomorphic changes were observed, with fine sediment being absorbed into a diverse mosaic of geomorphic features initiated by living trees and large wood. These observations underline the importance of vegetation for the geomorphic dynamics and adjustment of lowland, low‐energy rivers and its potential for inclusion in the development of sustainable, process‐based river management and restoration strategies. Copyright © 2015 John Wiley & Sons, Ltd.
- Post‐Spawning Survival and Downstream Passage of Landlocked Atlantic
Salmon (Salmo salar) in a Regulated River: Is There Potential for Repeat
- Authors: D. Nyqvist; O. Calles, E. Bergman, A. Hagelin, L. A. Greenberg
Abstract: Repeat salmonid spawners may make large contributions to total recruitment and long term population stability. Despite their potential importance, relatively little is known about this phase of the life history for anadromous populations, and nothing has been reported for landlocked populations. Here, we studied post‐spawning behaviour and survival of landlocked Atlantic salmon in relation to downstream dam passage in the River Klarälven, Sweden. Eight hydropower stations separate the feeding grounds in Lake Vänern from the spawning grounds in the River Klarälven, and no measures to facilitate downstream migration are present in the river. Forty‐nine percent of the salmon survived spawning and initiated downstream migration. Females and small fish had higher post‐spawning survival than males and large fish. The post‐spawners migrated downstream in autumn and spring and remained relatively inactive in the river during winter. Downstream migration speed in the free flowing part of the river was highly variable with a median of 9.30 km/day. Most fish passed the first hydropower station via upward‐opening spill gates after a median residence time in the forebay of 25 min. However, no tagged fish survived passage of all eight hydropower stations to reach Lake Vänern. This result underscores the need for remedial measures to increase the survival of downstream migrating kelts. Copyright © 2015 John Wiley & Sons, Ltd.
- Effect of Small Impoundments on Leaf Litter Decomposition in Streams
- Authors: J. G. Mbaka; R. B. Schäfer
Abstract: Leaf litter decomposition is an important process providing energy to freshwater biota. Flow regulation and dams can strongly alter freshwater ecosystems, but little is known about the effect of small impoundments on leaf litter decomposition rates in headwater streams. In this study, we examined the effect of small water storage impoundments (80 to 720 m3) on leaf litter decomposition by comparing sites located within 10‐m upstream and downstream of nine impoundments (Rhineland Palatinate, Germany) and sites located further upstream and downstream. The impoundments did not have a statistically significant effect on most physico‐chemical variables. However, the abundance of shredders and leaf litter decomposition rates decreased in study sites located within 10‐m upstream of the area flooded by impoundments. Small impoundments can locally reduce leaf litter decomposition rates in headwater streams. The effect of small impoundments on ecosystem functioning is minor and may require less attention by freshwater managers than other stressors, though this may differ for other ecological aspects such as connectivity. Copyright © 2015 John Wiley & Sons, Ltd.
- Pikeperch, Sander lucioperca Invasion in the Neretva River Watershed
(Bosnia and Herzegovina, Croatia) After Alteration of River Flow
- Authors: J. Pavličević; L. Glamuzina, A. Conides, N. Savić, I. Rozić, D. Klaoudatos, A. Kazić, B. Glamuzina
Abstract: The invasion history and the recent distribution, abundance and prey composition of pikeperch, Sander lucioperca in Neretva River watershed (Bosnia and Herzegovina and Croatia) are presented. The species was illegally/unintentionally introduced in Ramski Reservoir in the upper river part in 1986, while establishment of its abundant populations was reported during the 1990s in two connected artificial reservoirs. The research on the present abundance and food composition was executed during the 2012–2014 period. The results showed that pikeperch occupied most of the water bodies of the Neretva River, with an exception of natural river parts with gravel sediment and fast flow: all five artificial reservoirs (Ramski, Jablanički, Grabovica, Salakovac and Mostarski reservoirs) and lower wetland zone. However, the success and impact of colonization differ among water bodies, indicating pikeperch preference for warm and shallow reservoirs. Pikeperch prey is composed of different fish species abundant in specific water bodies. In artificial reservoirs, it preys mostly on introduced fish species, with a potential for controlling pumpkinseed abundance and biomass. Sampling carried out in Ramski Reservoir between 2013 and 1014 showed exclusive feeding on the introduced Leucaspius delineatus, and the establishment of a new food web, where only introduced species play significant roles. Copyright © 2015 John Wiley & Sons, Ltd.
- Assessing Groundwater Contribution to Streamflow of a Large Alpine River
with Heat Tracer Methods and Hydrological Modelling
- Authors: G. Ravazzani; D. Curti, P. Gattinoni, S. Della Valentina, A. Fiorucci, R. Rosso
Abstract: The contribution of groundwater to streamflow in Alpine catchments is still poorly understood, despite the fact that it may heavily impact hydrological balance and stream habitats. This paper presents the results of a field campaign based on experiments with heat tracer methods to assess the hyporheic flow during the low‐flow period of a large Alpine river in Italy. These measurements were employed to validate a distributed hydrological model that can be used to asses river–groundwater interaction in both low‐flow and high‐flow conditions. The results show that groundwater may have a relevant role during low‐flow periods, by increasing river discharge and during floods, by subtracting direct run‐off that is stored in river banks. Copyright © 2015 John Wiley & Sons, Ltd.
- Evaluation of the Logarithmic Law of the Wall for River Flows
- Authors: J. Petrie; P. Diplas
Abstract: The logarithmic law of the wall is commonly used to determine the shear stress applied to the river bed by the flow field. The shear stress calculation requires a velocity profile at the location of interest—data that can be obtained with a boat‐mounted acoustic Doppler current profiler (ADCP). ADCP survey procedures use either a fixed‐vessel (FV) or moving‐vessel (MV) with each providing different spatial and temporal resolution. MV procedures require significantly less field effort but the data lack the temporal resolution of FV measurements. This fact has motivated investigators to seek MV procedures and analysis techniques that provide equivalent results to FV measurements. This study compares results of the two survey procedures for depth‐averaged quantities (velocity and flow direction), mean velocity profiles, shear velocity and equivalent sand grain roughness. Mean velocity profiles are produced by time averaging for the FV measurements and spatial averaging for the MV measurements. Shear velocity and equivalent sand grain roughness are determined using simple linear regression applied to the logarithmic law of the wall. These procedures are demonstrated using data obtained during bankfull flow on the lower Roanoke River, North Carolina, USA. The results indicate comparable estimates of depth‐averaged quantities from both survey procedures. Estimates of the mean velocity profiles were found to be more variable. The agreement for shear velocity and equivalent sand grain roughness was generally poor indicating that further work is necessary to produce comparable results with MV survey procedures. Copyright © 2015 John Wiley & Sons, Ltd.
- A Twofold Strategy for Riparian Restoration: Combining a Functional Flow
Regime and Direct Seeding to Re‐establish Cottonwoods
- Authors: S. B. Rood; S. Kaluthota, K. M. Gill, E. J. Hillman, S. G. Woodman, D. W. Pearce, J. M. Mahoney
Abstract: The transboundary St Mary River drains Glacier National Park, USA, and was progressively dammed and diverted over the 20th century to support agricultural irrigation in northern Montana and southern Alberta, Canada. Following reduced instream flows, the riparian cottonwoods collapsed, and by 2000, few parental trees remained to provide seeds for cottonwood replenishment. As a novel twofold restoration strategy we: (1) worked with the dam operators to deliver a functional flow regime, a regulated instream flow pattern intended to recover some ecological function and specifically seedling recruitment, and (2) delivered cottonwood seeds by direct spreading and by sticking cuttings with seed catkins to allow gradual seed dispersal. The combination of river regulation and seeding enabled cottonwood colonization, and around 1.5% of the applied seeds produced seedlings after the first summer, at sites without livestock or heavy recreational use. Around 15% of those seedlings survived through the fourth summer, with mortality due to drought stress and flood scour, and establishment and survival were higher for the prairie cottonwood, Populus deltoides, than the narrowleaf cottonwood, Populus angustifolia. This study confirmed that the lack of seed source trees limited cottonwood colonization and demonstrated that the twofold restoration strategy provides promise for severe situations where parental trees have been lost. However, this would require substantial effort, and it would be more efficient to provide survivable instream flow patterns that avoid cottonwood collapse. Copyright © 2015 John Wiley & Sons, Ltd.
- Assessment of the Ecological Reservoir Operation in the Yangtze Estuary
Based on the Salinity Requirements of the Indicator Species
- Authors: C. Wang; Y. Yu, P. F. Wang, Q. Y. Sun, J. Hou, J. Qian
Abstract: In conventional reservoir operations, energy and economic benefits are typically optimized, and ecosystem values are only addressed as constraints. To reduce the negative influence of reservoir operation on the downstream ecological environment, ecological targets should be incorporated into reservoir operations. The concept of environmental flow was developed to define the quantity, quality and timing of water flows that are required to sustain freshwater and estuarine ecosystems. Based on the salinity requirements of the indicator species and the relationship between salinity and the freshwater inflows, environmental flows for the Yangtze Estuary were determined. Subsequently, an ecological reservoir operation model was established that incorporated the ecological target for the protection of the Qingcaosha water source; the Non‐dominated Sorting Genetic Algorithm II was applied to the model. Three typical periods of wet, normal and dry years were selected, and the operation results were analysed for the downstream Datong cross‐section and the environmental flows. The results showed that joint scheduling should be performed for the reservoirs upstream of the Yangtze Estuary. In June of wet and normal years, the current run‐off of the Datong should be reduced by 13.5% and 5%, respectively. In July and September of wet years, current run‐off should be reduced by 30.6% and 25.5%, respectively, as these reductions will not negatively affect the drinking‐water sources. The results of this study should provide guidance in decision‐making to improve the operation of the Three Gorges Reservoir. Copyright © 2015 John Wiley & Sons, Ltd.
- Diet Breadth and Variability in Sander spp. Inferred from
- Authors: M. J. Fincel; S. R. Chipps, B. D. S. Graeb, M. L. Brown
Abstract: We used stable isotopes of carbon and nitrogen to evaluate trophic similarity between sauger Sander canadensis and walleye S. vitreus in three Missouri River impoundments characterized by unique differences in riverine habitat. Mean δ15N was similar for sauger and walleye in each reservoir ranging from 15.7 to 17.8‰ for sauger and 15.2 to 17.7‰ for walleye. However, mean δ13C was greater for sauger (−24‰) than for walleye (−25‰) in Lake Oahe (lacustrine habitat), where rainbow smelt Osmerus mordax is an important prey species for walleye. Variation in δ15N and δ13C values was similar between walleye and sauger in Lewis and Clark Lake (riverine habitat), but was greater for sauger than for walleye in Lake Oahe, implying that in pelagic environments, sauger exhibit a larger diet breadth and lower diet consistency compared with walleyes. Isotope analyses support observations from traditional gut content studies that diet overlap between sauger and walleye varies with environmental conditions and is more similar in riverine food webs than in large lakes and impoundments. Copyright © 2015 John Wiley & Sons, Ltd.
- The Effects of Improved Water Quality on Fish Assemblages in a Heavily
Modified Large River System
- Authors: J. Parker; J. Epifanio, A. Casper, Y. Cao
Abstract: A long history of human alterations has affected the hydrology, physical habitat and water quality of most large river ecosystems. For more than a century, the Illinois River Waterway has been subject to channelization, damming, dredging, agricultural runoff and industrial and municipal effluents. This study evaluates how subsequent improvements in water quality have influenced long‐term changes in fish assemblages (1983–2010). We used five metrics to characterize the changes in fish assemblages. These metrics depicted shifts in the abundance and biomass of predatory and native fishes and species richness. Random forests (RF) and multiple linear regressions (MLRs) were used to relate the fish metrics to individual water quality and weather variables, with weather primarily used to account for inter‐annual variation. Model performances varied spatially and among fish metrics (0 ≤ pseudo‐R2 ≤ 0.73 for RF; 0.10 ≤ adjR2 ≤ 0.88 for MLR), but dissolved oxygen, un‐ionized ammonia and water clarity were often the best predictors. As the distance downstream of major pollutant sources increased, water quality became less important for explaining the changes in fish metrics and weather more important. These results indicate that water quality improvement largely accounts for fish assemblage recovery in the river system, although within some reaches we examined, weather had substantial compounding effects. The results could be used to prioritize water quality variables for long‐term monitoring and aid in predicting fish assemblage responses to future changes in water quality and climate. Copyright © 2015 John Wiley & Sons, Ltd.
- Numerical Modelling of Braided Rivers with
Structure‐from‐Motion‐Derived Terrain Models
- Authors: L. Javernick; D. M. Hicks, R. Measures, B. Caruso, J. Brasington
Abstract: The development of three‐dimensional reconstructions of channel morphology has historically been limited by the high costs of geospatial data collection and software modelling. Advances in image processing, sensor technology and portable remote‐sensing platforms, however, now offer the opportunity to derive survey quality terrain models at significantly reduced cost and without traditional deployment and logistical constraints. There is a pressing need to establish whether new geospatial technologies such as structure‐from‐motion photogrammetry can be used to deliver topographic data products that are suitable for higher‐dimensional hydrodynamic modelling. To address this question, we evaluate the results of simulations using Delft3D that were designed to model distributed, depth‐averaged flows in a wide, shallow, gravel‐bed braided river. The topography for these simulations was derived from digital elevation models (DEMs) generated using structure‐from‐motion and optical bathymetric mapping of two linked reaches of the Ahuriri River, New Zealand. The DEM quality achieved vertical surface errors of 0.10 m in non‐vegetated areas and 0.20 m in inundated areas. Simulations with 1.5 m and 2.5 m resolution grids for low‐flow, medium‐flow and high‐flow conditions were calibrated and tested against field real‐time kinematic‐global navigation satellite system observations. Results revealed that modelled depth errors were comparable to the DEM uncertainty, while simulated and observed inundation patterns achieve a maximum of 81% agreement. Given the complexity of the braided network and shallow flow depths, these simulations provide a powerful demonstration of the suitability of these terrain models for hydrodynamic applications. Copyright © 2015 John Wiley & Sons, Ltd.
- Evaluating Uncertainty in Physical Habitat Modelling in a
High‐Gradient Mountain Stream
- Authors: D. Turner; M. J. Bradford, J. G. Venditti, R. M. Peterman
Abstract: Predictions of habitat‐based assessment methods that are used to determine instream flow requirements for aquatic biota are uncertain, but instream flow practitioners and managers often ignore those uncertainties. Two commonly recognized uncertainties arise from (i) estimating the way in which physical habitat within a river changes with discharge and (ii) the suitability of certain types of physical habitat for organisms. We explored how these sources of uncertainty affect confidence in the results of the British Columbia Instream Flow Methodology (BCIFM), which is a commonly used transect‐based habitat assessment tool for small‐scale water diversions. We calculated the chance of different magnitudes of habitat loss resulting from water diversion using a high‐gradient reach of the North Alouette River, BC, as a case study. We found that uncertainty in habitat suitability indices for juvenile rainbow trout generally dominated uncertainty in the results of the BCIFM when large (>15) numbers of transects were used. In contrast, with small numbers of transects, variation in physical habitat among sampled transects was the major source of uncertainty in the results of the BCIFM. Presentations of results of the BCIFM in terms of probabilities of different amounts of habitat loss for a given flow can help managers prescribe instream flow requirements based on their risk tolerance for fish habitat loss. Copyright © 2015 John Wiley & Sons, Ltd.
- The Effect of Hydrologic Alteration on Capture Efficiency of Freshwater
Fishes in a Highly Modified Prairie Stream
- Authors: K. R. Neufeld; M. S. Poesch, D. A. Watkinson
Abstract: Hydrology is a defining feature of aquatic ecosystems. Changes in stream hydrology, due to climate change, water use and impoundment, have been shown to negatively affect fish populations. Assessing changes in hydrology and its effect on fish populations and communities remains an important consideration for aquatic monitoring programmes across the globe. In this study, we used the Milk River in southern Alberta as a model system to understand how hydrologic alteration may also affect capture probabilities of fishes and impact instream monitoring programmes. The Milk River receives the majority of its April to October flow via an inter‐basin transfer from the St. Mary River, drastically altering the hydrologic regime and instream habitats for fishes during this augmentation period. We estimated species‐specific seine net capture probabilities of fishes in the Milk River during augmentation and natural flow periods using depletion surveys in both open and enclosed sites. Using habitat data collected during the seine surveys, linear mixed‐effects models were created with capture efficiency as the dependent variable. Models were compared using corrected Akaike's information criterion, and the relative contributions of the different variables to the top models were examined. We found that species and flow characteristics, such as water velocity and the state of augmentation, played a prominent role in many of the top models explaining variation in capture efficiency. These results demonstrate that changes to stream hydrology clearly have the potential to impact gear efficiency and individual species assessments. Stream monitoring programmes, which aim to determine long‐term trends in aquatic ecosystem health, need to be mindful that any change to stream hydrology—from climate change, fragmentation or stream alteration—can alter capture efficiency of the sampling gear and inadvertently alter species‐specific trends. Copyright © 2015 John Wiley & Sons, Ltd.
- Advances on Modelling Riparian Vegetation—Hydromorphology
- Authors: L. Solari; M. Van Oorschot, B. Belletti, D. Hendriks, M. Rinaldi, A. Vargas‐Luna
Abstract: Riparian vegetation actively interacts with fluvial systems affecting river hydrodynamics, morphodynamics and groundwater. These interactions can be coupled because both vegetation and hydromorphology (i.e. the combined scientific study of hydrology and fluvial geomorphology) involve dynamic processes with similar temporal and spatial scales. To predict and assess the consequences of restoration measures, maintenance operations or human pressures in rivers, managers and planners may wish to model these interactions considering the different and interdisciplinary implications in the fields of ecology, geomorphology and hydrology. In this paper, we review models that are currently available and that incorporate the processes that relate riparian vegetation to hydromorphology. The models that are considered include those emphasizing hydraulic‐geomorphological processes (such as flow resistance, sediment transport and bank dynamics) as well as those emphasizing ecological processes (seed dispersal, plant survival, growth, succession and mortality). Models interpreting the coupled evolution between riparian vegetation and river morphology and groundwater are also presented. The aim is to provide an overview of current modelling capabilities and limitations and to identify future modelling challenges. Copyright © 2015 John Wiley & Sons, Ltd.
- Downstream Swimming Behaviour of Catadromous and Potamodromous Fish Over
- Authors: A. T. Silva; C. Katopodis, M. F. Tachie, J. M. Santos, M. T. Ferreira
Abstract: Flow characteristics associated with spillways are important to restore ecological connectivity because spillways can either constrain or offer safe routes for downstream passage of fish. We studied the hydrodynamics of flow and downstream movement behaviour of the catadromous European eel (Anguilla anguilla) and the potamodromous Iberian barbel (Luciobarbus bocagei) in spillways with upstream face inclinations of θ = 90° (standard) 45° and 30° (modified). The standard spillway was tested for two water depths (H = 32 and 42 cm). Modified spillways facilitated downstream passage and reduced delay times of passage of the European eel. Upstream of the 90° spillway, distinct recirculation areas were observed, and associated turbulence strongly hampered downstream passage of fish. Both species were found to avoid turbulence, but barbel displayed stronger avoidance for areas of rapid changes in flow velocity when comparing to eels. Overall, eels were faster in passing the spillway and had a higher downstream passage success (80%) than barbel (32%). Eels were predominantly thigmotactic in contrast to barbel, which showed limited contact with structures. The results suggest that modified spillways may enhance passage survival. Copyright © 2015 John Wiley & Sons, Ltd.
- From the Source to the Outlet: understanding the Distribution of Invasive
Knotweeds along a North American River
- Authors: M.‐C. Duquette; A. Compérot, L. F. Hayes, C. Pagola, F. Belzile, J. Dubé, C. Lavoie
Abstract: Understanding the drivers of exotic plant invasions along waterways is crucial for helping environmental managers devise effective control strategies. We combined a field survey, molecular data and a logistic regression model to further our understanding of the spatial distribution of Japanese (Fallopia japonica) and Bohemian (Fallopia × bohemica) knotweeds along the entire course (185 km) of a river located in Québec (Canada). Both knotweeds were abundant along the river, but each had a distinct spatial distribution pattern. Only one genotype for each knotweed species or hybrid was found, suggesting that the individuals established along the Chaudière River resulted from the propagation of rhizome or stem fragments. The distance from the nearest town or village was the only explanatory variable significantly correlated to the spatial distribution of knotweeds. However, spatial autoregressive coefficients were significant, indicating that knotweeds were more likely to occur close to other knotweeds. In summary, the invasion was probably initiated by the introduction, in riverside towns and villages, of a few individuals of the same genotype. The clones then spread vegetatively, probably during spring floods. The rhizome and stem fragments spread over short distances, dispersing downstream from urban centres. The introduction of just two knotweed genotypes along the Chaudière River was sufficient to initiate a massive riverside colonization, as few riparian vegetation types were apparently able to resist knotweed invasion. Copyright © 2015 John Wiley & Sons, Ltd.
- Path Selection of Atlantic Salmon (Salmo salar) Migrating Through a
- Authors: D.‐E. Lindberg; K. Leonardsson, H. Lundqvist
Abstract: We constructed a model that predicted path selection of Atlantic salmon. Our basic assumption for the model was that Atlantic salmon optimize migration by selecting a path that minimizes water resistance. The model prediction was compared with observations in a fishway, and the results were within expectations. It appeared like the fishway design and flow configuration at our study site caused some problems for the fish to discover both of the available paths. Therefore, only 53% of female fish and 67% of male fish selected the optimal path in the beginning of the fishway, but 92% of female fish and 97% of male fish selected the optimal path at the end of the fishway. Velocity over ground was very low, which is likely because every weir in the fishway was an obstacle for the fish. This knowledge can be used to improve future fishway design, or improve flow configuration for existing fishways. Copyright © 2015 John Wiley & Sons, Ltd.
- Effect of Adverse Pressure Gradient and Different Vegetated Banks on Flow
- Authors: H. Afzalimehr; M. Moradian, J. Gallichand, J. Sui
Abstract: This study examines velocity components in 3D and shear stress distributions in flows with adverse pressure gradient over a gravel‐bed channel using three types of vegetation on banks, rice, straw and Typha stems. Results of this experimental study are compared with those for flows in the bare bank channel. Results show that the flows with adverse pressure gradient are not self‐similar in vegetated and bare banks channels. The logarithmic law and parabolic law can be used to well describe flow in the inner and outer regions, respectively, but with different relative flow depths. Shear stress distributions depend on nature of bank roughness and the secondary flow effects because of small values of the aspect ratio and adverse pressure gradient. Quadrant analysis is performed to investigate the effect of different vegetation covers on the Reynolds stress distributions at the central axis of channel and near the vegetated banks. Vegetation covers influence the contributions of different quadrants to the shear stress distribution, showing that sweeps and ejections are dominant events for all vegetated banks for near bed region. However, near the water surface the contributions of outwards and inwards for banks with Typha stems are more important than those for rice and straw. Instead of using a single value for friction factor, for different vegetated banks, a range of friction factor has to be applied in river restoration projects. Vegetated banks result in an increase of more than 60% in friction factor in comparison with that for bare banks under adverse pressure gradient flows. Copyright © 2015 John Wiley & Sons, Ltd.
- Fragmentation of an Intermittent Stream During Seasonal Drought:
Intra‐annual and Interannual Patterns and Biological Consequences
- Authors: J. L. Hwan; S. M. Carlson
Abstract: Intermittent streams lose surface flow during some portion of the year and can be important breeding and rearing habitats for stream biota. However, habitat contraction and deteriorating water quality across the summer can result in harsh conditions and mortality. We explored patterns of drying in a small intermittent stream across the summer in Mediterranean‐climate California, including across 4 years that differed in antecedent precipitation. Wet–dry mapping revealed earlier stream fragmentation following dry winters and that entire sections of the stream varied in their propensity to dry suggesting an important influence of geomorphology on drying. Within two ‘slow‐drying’ reaches, initial riffle volumes were higher following wetter winters, but the rate of riffle drying was higher following wet years, presumably because higher initial volumes resulted in greater drying capacity. Initial pool volumes were similar across years, but the rate of pool drying was faster following dry versus wet winters (pool half‐life ranged from 9.7 weeks in the driest year to 26.3 weeks in the wettest year). Stream temperature differed among years, but differences were slight, and temperatures rarely exceeded optimal conditions for trout growth. We observed limited movement of trout during drier years and found that movement was negatively associated with pool depth, riffle length and date, and positively associated with riffle volume. Overall, we found that antecedent rainfall influenced variability in pool drying more than riffle drying, that entire sections of the creek varied in their propensity to dry and that biological fragmentation preceded physical fragmentation by 3 to 7 weeks. Copyright © 2015 John Wiley & Sons, Ltd.
- A Classification of Stream Water Temperature Regimes in the Conterminous
- Authors: A. Maheu; N. L. Poff, A. St‐Hilaire
Abstract: Temporal variability in water temperature plays an important role in aquatic ecosystems, yet the thermal regime of streams has mainly been described in terms of mean or extreme conditions. In this study, annual and diel variability in stream water temperature was described at 135 unregulated, gauged streams across the USA. Based on magnitude, amplitude and timing characteristics of daily water temperature records ranging from 5 to 33 years, we classified thermal regimes into six distinct types. This classification underlined the importance of including characteristics of variability (amplitude and timing) in addition to aspects of magnitude to discriminate thermal regimes at the continental scale. We used a classification tree to predict thermal regime membership of the six classes and found that the annual mean and range in the long‐term air temperature average along with spring flows were important variables defining the thermal regime types at the continental scale. This research provides a framework for a comprehensive characterization of the thermal regimes of streams that could provide a basis for future assessment of changes in water temperature caused by anthropogenic activities such as dams, land use changes and climate change. Copyright © 2015 John Wiley & Sons, Ltd.
- Forecasting of Hydrographs to Simulate Long Term Recharge From Rivers in
Numerical Models of Mining Reservoirs; Application to A Coal Mine in NW
- Authors: A. Ordóñez; C. Andrés, R. Álvarez
Abstract: Although the natural permeability of rocks in the Asturian Central Coal Basin (NW Spain) is generally low, intensive mining activities over many decades has given rise to fracture flow paths that are far more permeable than those associated with the natural lithology. Abandoned and flooded mining works set up artificial ‘pseudo‐karst’ aquifers, which can act as underground reservoirs, with many potential applications. In particular, a mining reservoir shaped by two connected mining shafts within the River Turón basin has been studied. A runoff model was used to produce accurate simulations of streamflow in three different gauging stations during a monitored period of 2 years. The purpose was to use this model in the forecast situation, in order to predict long‐term situations in a hydrogeological FEFLOW model. It was necessary to develop depletion curves for each gauging station based on the available daily effective rainfall and measured flow data, as well as the knowledge of the basin characteristics. The resulting simulated hydrographs were very similar to the measured hydrographs during the monitored period, so the adequate adjusting allows input of the flow for forecast purposes. The model produced forecast hydrographs that had a r = 0.8 and difference in annual volume ranging from 1.6% to 5%. The defined model was applied to a rainfall data set of 30 years, and the average recharge from the river to the mining reservoir could be adequately estimated. The method developed needs to be refined and tested on additional years, but the approach appears to be applicable to operational runoff forecasting for numerical models input data. Copyright © 2015 John Wiley & Sons, Ltd.
- Predicting Floodplain Hypoxia in the Atchafalaya River, Louisiana, USA, a
Large, Regulated Southern Floodplain River System
- Authors: T. E. Pasco; M. D. Kaller, R. Harlan, W. E. Kelso, D. A. Rutherford, S. Roberts
Abstract: The Atchafalaya River Basin Floodway (ARBF), a regulated river/floodplain distributary of the Mississippi River, experiences an annual flood pulse that strongly influences floodplain physicochemistry. We developed several metrics to investigate the relationship between the timing and magnitude of the flood pulse and floodplain hypoxia, which in most years is a spatially extensive and temporally prolonged problem in the lower ARBF. Principal components analysis of flood metrics from 2001 to 2009 revealed contrasting flood types (early cool and late warm), but component‐based general linear models were unable to predict the magnitude of hypoxia in ARBF water management areas (WMAs). Further analyses based on temperature and geographic information system‐determined WMA inundation with generalized additive models (GAMs) revealed WMA‐specific patterns of hypoxia, but the likelihood of hypoxia consistently increased when temperatures approached 20°C and inundation rose above 20–30%. Validation with held‐out data based on logistic regression indicated that the models constructed with the 2001–2009 temperature and inundation data were able to accurately predict the probabilities of hypoxia in two WMAs based on data collected from 2010 to 2013. The GAMs were an effective tool for visualizing and predicting the probability of hypoxia based on two easily generated parameters. Our analyses indicate that modification of the Atchafalaya River flood pulse could reduce the magnitude of hypoxia within the lower ARBF, subject to engineering (control structure operation) and economic (commercial fisheries production) constraints, by minimizing floodplain inundation after water temperatures reach 20°C. Copyright © 2015 John Wiley & Sons, Ltd.
- Fish Movements and Passage Through a Water Control Structure: River Stage
and Floodplain Connectivity
- Authors: S. Tripp; K. Jack Killgore, J. E. Garvey
Abstract: The St. John's Bayou water control structure near New Madrid, MO, connects the main Mississippi River to two large backwater areas called the New Madrid Floodway and St. John's Bayou. While this area has been altered, the New Madrid Floodway and St. John's Bayou account for the only substantial portion of the historic Mississippi River floodplain that remains and provides the only critical connection between backwater/floodplain habitat and the river. Fish passage was evaluated during April–December 2010 using ultrasonic telemetry. Stationary receivers were placed strategically at five locations above and below the structure in St. John's Bayou, in the floodway and the outlet to the Mississippi River. A total of 100 individuals representing 14 species were tagged. Total number of detections during an 8‐month period was 1 264 717. Fifteen individuals representing five species moved into the Mississippi and Ohio rivers; seven individuals returned to St. John's Bayou. Thirteen of the 14 species moved upstream through the structure. Of the 85 individuals that stayed in the bayou, 29 fish passed through the structure for a total of 92 passage events. The downstream : upstream passage was roughly 50:50. Passage was correlated with river rise, with frequency of passage being higher in spring, but passage occurred each month during the study. Copyright © 2015 John Wiley & Sons, Ltd.
- Habitat Suitability Criteria via Parametric Distributions: Estimation,
Model Selection and Uncertainty
- Authors: Nicholas A. Som; Damon H. Goodman, Russell W. Perry, Thomas B. Hardy
Abstract: Previous methods for constructing univariate habitat suitability criteria (HSC) curves have ranged from professional judgement to kernel‐smoothed density functions or combinations thereof. We present a new method of generating HSC curves that applies probability density functions as the mathematical representation of the curves. Compared with previous approaches, benefits of our method include (1) estimation of probability density function parameters directly from raw data, (2) quantitative methods for selecting among several candidate probability density functions, and (3) concise methods for expressing estimation uncertainty in the HSC curves. We demonstrate our method with a thorough example using data collected on the depth of water used by juvenile Chinook salmon (Oncorhynchus tschawytscha) in the Klamath River of northern California and southern Oregon. All R code needed to implement our example is provided in the appendix. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.
- Trade‐Offs in Seed Dispersal Strategies Across Riparian Trees: The
How Matters as Much as the When
- Authors: E. González; B. Bourgeois, A. Masip, A. A. Sher
Abstract: Riparian Salicaceae are prolific producers of short‐lived seeds that require very restrictive hydro‐geomorphic conditions for establishment. It is generally assumed that if floods are able to create nursery sites timed with seed dispersal, recruitment will occur. Other spatial and temporal seed dispersal patterns besides the dispersal period have historically received little attention. However, seed dispersal patterns can be highly variable between regions, species and over the years. In this paper, we report the seed dispersal patterns of three dominant riparian Salicaceae trees in Europe: Populus alba, P. nigra and Salix alba to suggest possible trade‐offs between seed dispersal patterns, germinability, longevity and establishment. Seed rain of the three species was monitored in 33 glue‐coated traps for three months yearly from 2006 to 2008 in an 8‐km stretch of the Middle Ebro River (N Spain), which has a pluvio‐nival regime. P. alba dispersed seeds earlier during a shorter time period and with a fewer number of seed release pulses compared with P. nigra, and especially with S. alba. With overlapping seed dispersal periods, the two latter species occupy similar landform units but rarely compete with P. alba, usually at higher elevations, as shown in a previous study in the same study area. The three species had very high germinability immediately after release (>90%), but longevity in S. alba was eight times shorter than that of its two Populus counterparts. We suggest that S. alba has compensated its lower seed quality with a more spaced seed release in several pulses of similar magnitude. With similar seed dispersal patterns and germinability but a higher longevity, P. nigra had a much higher density of individuals than S. alba in the recruitment zones of the study area. We hope that our results may inform river managers about how to optimize river flows to promote sexual regeneration of these species. Copyright © 2015 John Wiley & Sons, Ltd.
- The Disconnected Sediment Conveyor Belt: Patterns of Longitudinal and
Lateral Erosion and Deposition During a Catastrophic Flood in the Lockyer
Valley, South East Queensland, Australia
- Authors: C. J. Thompson; K. Fryirs, J. Croke
Abstract: The sediment (dis)connectivity concept is the water‐mediated transfer of sediment between different compartments of a catchment sediment cascade involving four possible dimensions or linkages (longitudinal, lateral, vertical and temporal). Quantifying the strength of these linkages within and between compartments provides a means to understand the internal sediment flux dynamics of a catchment. The aims of this paper are to examine (1) the dynamics of longitudinal and lateral (dis)connectivity by quantifying patterns of erosion and deposition that occurred during a catastrophic flood, and (2) how the patterns of connectivity can be changed through management actions that better utilise floodplain sediment storages. Multi‐temporal LiDAR and air photos are used to quantify volumetric change with respect to geomorphic settings and units. The results show that over the length of the trunk stream, the high‐magnitude event was net depositional with high longitudinal sediment disconnectivity. At the reach scale, an alternating pattern of high and low longitudinal connectivity associated with contraction and expansion zones was evident. The efficiency of sediment transfer from the uppermost compartment to the most downstream compartment decreased exponentially, while the strength of lateral connectivity increased for each expansion reach. Modelling results show that increasing channel boundary roughness along expansion reaches with riparian revegetation can increase the frequency of lateral connectivity and floodplain sediment storage, thereby decreasing reach‐to‐reach connectivity and reducing end‐of‐catchment sediment delivery. This contrasts with the current trend of building levees along the bank tops of expansion reaches, which decrease lateral connectivity and increase reach‐to‐reach connectivity. Copyright © 2015 John Wiley & Sons, Ltd.
- Influence of Flow on Community Structure and Production of
Snag‐Dwelling Macroinvertebrates in an Impaired Low‐Gradient
- Authors: E. A. Scholl; H. M. Rantala, M. R. Whiles, G. V. Wilkerson
Abstract: The natural flow regime of rivers has been altered throughout the world in a variety of ways, with many alterations resulting in reduced flows. While restoring impaired systems remains a societal imperative, a fundamental understanding of the effects of reduced flows on river ecosystem structure and function is needed to refine restoration goals and guide implementation. We quantified the effects of chronic low flows on snag‐dwelling macroinvertebrate community structure and production in a low‐gradient river. Macroinvertebrates commonly associated with flowing water (e.g. passive filter‐feeders (PFF)) and higher quality habitats (e.g. Ephemeroptera, Plecoptera and Trichoptera (EPT)) had significantly higher abundance and biomass, and showed trends of higher production, in faster flowing reaches upstream of a hydrologic disconnection created by a drainage ditch. The presence of EPT and PFF groups resulted in a significantly more diverse community composed of larger‐sized individuals compared with downstream, low‐flow reaches, where smaller‐bodied taxa (e.g. small crustaceans), and groups reflective of degraded conditions (e.g. Oligochaeta, Isopoda and Chironomidae) dominated production. Multivariate analyses suggested that differences between these two disparate communities were driven by water velocity and organic matter resources. Mean estimates of total community production did not differ significantly between the two reaches, however, there were areas in low‐flow reaches that attained high secondary production because of patchily distributed and highly productive chironomids. Results demonstrate that long‐term reductions in flows, even in a low‐gradient river, can lead to significant shifts in macroinvertebrate communities, ultimately influencing energy flow pathways in stream food webs. Copyright © 2015 John Wiley & Sons, Ltd.
- Hydrologic Response of Streams Restored with Check Dams in the Chiricahua
- Authors: L. M. Norman; F. Brinkerhoff, E. Gwilliam, D. P. Guertin, J. Callegary, D. C. Goodrich, P. L. Nagler, F. Gray
Abstract: In this study, hydrological processes are evaluated to determine impacts of stream restoration in the West Turkey Creek, Chiricahua Mountains, southeast Arizona, during a summer‐monsoon season (June–October of 2013). A paired‐watershed approach was used to analyze the effectiveness of check dams to mitigate high flows and impact long‐term maintenance of hydrologic function. One watershed had been extensively altered by the installation of numerous small check dams over the past 30 years, and the other was untreated (control). We modified and installed a new stream‐gauging mechanism developed for remote areas, to compare the water balance and calculate rainfall–runoff ratios. Results show that even 30 years after installation, most of the check dams were still functional. The watershed treated with check dams has a lower runoff response to precipitation compared with the untreated, most notably in measurements of peak flow. Concerns that downstream flows would be reduced in the treated watershed, due to storage of water behind upstream check dams, were not realized; instead, flow volumes were actually higher overall in the treated stream, even though peak flows were dampened. We surmise that check dams are a useful management tool for reducing flow velocities associated with erosion and degradation and posit they can increase baseflow in aridlands. © 2015 The
Authors . River Research and Applications published by John Wiley & Sons, Ltd.
- Potential Impacts of Stream Crossing Traffic On Macroinvertebrate
Communities in the Missouri Ozark River
- Authors: R. L. S. Heth; D. E. Bowles, J. E. Havel
Abstract: Depending on intensity, physical disturbance can either decrease or increase diversity of stream macroinvertebrate communities. Recreational activities in parks are one component of physical disturbance. Our objective was to evaluate the effects of stream crossings and recreational traffic on macroinvertebrate assemblages. Five stream‐crossing sites were sampled during winter and summer in the Current River, Ozarks National Scenic Riverways, Missouri, USA. Stream‐crossing traffic was assessed using trail cameras. At each site, macroinvertebrates were collected from four locations: riffle upstream of crossing, riffle immediately downstream of crossing and second and third riffles downstream of crossing. We compared sites and locations within sites using standard metrics (taxa richness, Ephemeroptera, Plecoptera and Trichoptera richness, biotic index and diversity) and their composite stream condition index (SCI) plus multivariate analyses (Nonmetric multidimensional scaling and correlations). Stream crossings had no detectable impacts on macroinvertebrate communities in winter, but in summer location, effects were present. Patterns in SCI scores across locations varied among sites, with no consistent declines in macroinvertebrate diversity downstream of crossings. Longitudinal stream effects dominated over potential stream‐crossing effects on macroinvertebrate communities. Overall, high SCI scores indicated that current levels of stream crossings and traffic in this scenic riverway do not pose a threat to macroinvertebrate communities at the spatial and temporal scale of this study. Copyright © 2015 John Wiley & Sons, Ltd.
- Growth and Life History Patterns of a Small‐bodied Stream Fish,
Cottus cognatus, in Hydropeaking and Natural Rivers of Northern Ontario
- Authors: M. J. Bond; N. E. Jones, T. J. Haxton
Abstract: Hydroelectric facilities can dramatically alter the quantity and quality of fish habitat; however it is not well known how these habitat changes affect the growth and life history of fish. We examine the growth and life history of slimy sculpin (Cottus cognatus), a small‐bodied sedentary, benthic stream fish, in two regulated and eight unregulated tributaries of Lake Superior, Canada. Among rivers, we found that slimy sculpin grew faster in the regulated Magpie River than in nearby unregulated systems, whereas growth in the Michipicoten River was intermediate. Sculpin were also in better condition in the regulated Magpie and Michipicoten than in nearby natural rivers. Faster growth of sculpin, however, potentially led to their rapid maturity and higher instantaneous mortality in regulated rivers. Within the regulated rivers, there are strong longitudinal gradients in growth, with sculpin at sampling sites near the dams growing more rapidly, maturing earlier and attaining a larger size‐at‐age than sculpin at sites farther downstream or in natural systems. Differences in sculpin life history traits within rivers closely followed spatial patterns in food availability. We caution future researchers and managers to acknowledge the longitudinal gradients in abiotic and biotic conditions below dams early in experimental designs and monitoring programmes and how this may impact the measures of central tendency and statistical power when comparing rivers. Copyright © 2015 John Wiley & Sons, Ltd.
- Assessing the Relationship Between River Mobility and Habitat
- Authors: G. Choné; P. M. Biron
Abstract: Human interventions that limit channel mobility such as bank stabilization are frequent in riparian zones in urban or agricultural environments. This is potentially problematic because channel mobility is an important geomorphological and ecological agent that structures natural instream and riparian ecosystems. This study aims to (1) quantify the relationship between mobility and three types of habitat‐related features, namely bars, oxbow lakes and log jams, for a 54‐km‐long reach of the Yamaska Sud‐Est River (Quebec, Canada), which runs from the forested Appalachian Mountains to the agricultural St‐Lawrence lowlands, and (2) evaluate the impact of human interventions and geomorphological characteristics on these three features. Channel mobility was measured from historical aerial photos for the period 1950–2009. A combination of high‐resolution aerial photos, LiDAR digital elevation model, and field observations was used to measure and map sediment bars, oxbow lakes and log jams, as well as several geomorphological characteristics (channel width, slope, sinuosity and floodplain width). A strong link between the mobility and the presence of habitat features is revealed, but local geomorphological contexts result in different mobility patterns responsible for specific habitats. Floodplain to channel width ratio appears as the best geomorphological factor predicting habitat diversity. Human intervention, mostly through bank stabilization, also appears to be a key factor limiting mobility and its related habitats. These results highlight the importance of defining a protected mobility corridor along rivers where geomorphic processes such as bank erosion can freely occur, as it is an essential process that should be integrated in land use planning and river management. Copyright © 2015 John Wiley & Sons, Ltd.
- Explaining Spatial Patterns of Mussel Beds in a Northern California River:
The Role of Flood Disturbance and Spawning Salmon
- Authors: Christine L. May; Bonnie S. Pryor
Abstract: Despite considerable effort, predicting habitat preferences for freshwater mussels has remained elusive. This study identified four parameters that correlate with bed stability to decipher fine‐scale spatial patterning of habitat use by the western pearl shell mussel (Margaritifera falcata) in the Trinity River of Northern California. Logistic regression analysis correctly predicted the occurrence of 83% of mussel bed areas based on water depth, velocity, substrate size, and distance to the stream bank as estimated from hydrodynamic modelling of low‐flow conditions. These parameters coincide with bed stability at high flow and provide support for the ‘refugia hypothesis’. Our data clearly demonstrate that mussel beds occupied the most stable portions of the riverbed; however, habitat was partitioned with one of their primary host fish, Chinook salmon (Oncorhynchus tshawytscha), a species that also requires stable bed areas for spawning. Mussels occupied significantly deeper and lower velocity areas that were closer to the streambank compared with spawning salmon, but where habitats directly overlapped (30% of potential mussel habitat) mussels were excluded because the act of spawning disturbs the riverbed. By necessity, mussels and salmon must co‐exist, but results of this study indicate that they compete for stable bed areas that may be limiting in dynamic river systems. Copyright © 2015 John Wiley & Sons, Ltd.
- Age‐0 Channel Catfish Ictalurus Punctatus Growth Related to
Environmental Conditions in the Channelized Missouri River, Nebraska
- Authors: N. P. Hogberg; M. J. Hamel, M. A. Pegg
Abstract: Large river paradigms suggest that natural flow regimes are critical for maintaining instream habitats and promoting production and growth of native aquatic organisms. Modifications to the Missouri River, Nebraska, within the past 100 years have drastically reduced shallow water habitat, homogenized the flow regime, and contributed to declines in several native species. Despite drastic flow modifications, several metrics of the Missouri River's flow regime still vary across years. We related age‐0 channel catfish growth to environmental conditions in the channelized Missouri River, Nebraska, between 1996 and 2013 using an information theoretic approach. Growth rate was most influenced by growing season duration and duration of discharges below the 25th percentile of 30‐year daily Missouri River discharges. Periods of low water may be important for juvenile growth because of channel modifications that limit critical shallow water habitat during higher within‐bank flows. Exclusion of peak discharge and peak discharge timing in the best model to predict growth is counter to conventional thoughts on river fish responses to hydrological conditions but may be reflective of the general lack of high‐magnitude flooding during the majority of our study. Future efforts to relate juvenile fish growth to environmental conditions can provide guidance for water management in the Missouri River and other regulated North American rivers. Copyright © 2015 John Wiley & Sons, Ltd.
- River Temperature Modelling by Strahler Order at the Regional Scale in the
Loire River Basin, France
- Authors: A. Beaufort; F. Moatar, F. Curie, A. Ducharne, V. Bustillo, D. Thiéry
Abstract: Daily water temperature was simulated at a regional scale during the summer period using a simplified model based on the equilibrium temperature concept. The factors considered were heat exchanges at the water/atmosphere interface and groundwater inputs. The selected study area was the Loire River basin (110 000 km2), which displays contrasted meteorological, hydrological and geomorphological features. To capture the intra‐basin variability of relevant physical factors driving the hydrological and thermal response of the system, the modelling approach combined a semi‐distributed hydrological model, simulating the daily discharge at the outlet of 68 subwatersheds (drainage area between 100 and 3700 km2), and a thermal model, simulating the average daily water temperature for each Strahler order in each subwatershed. Simulations at 67 measurement stations revealed a median root mean square error (RMSE) of 1.9°C in summer between 2000 and 2006. Water temperature at stations located more than 100 km from their headwater was adequately simulated (median RMSE
- Water‐Quality Assessment of the Lower Grand River Basin, Missouri
and Iowa, USA, in Support of Integrated Conservation Practices
- Authors: D. H. Wilkison; D. J. Armstrong
Abstract: The effectiveness of agricultural conservation programmes to adequately reduce nutrient exports to receiving streams and to help limit downstream hypoxia issues remains a concern. Quantifying programme success can be difficult given that short‐term basin changes may be masked by long‐term water‐quality shifts. We evaluated nutrient export at stream sites in the 44 months that followed a period of increased, integrated conservation implementation within the Lower Grand River Basin. These short‐term responses were then compared with export that occurred in the main stem and adjacent rivers in northern Missouri over a 22‐year period to better contextualize any recent changes. Results indicate that short‐term (October 2010 through May 2014) total nitrogen (TN) concentrations in the Grand River were 20% less than the long‐term average, and total phosphorus (TP) concentrations were 23% less. Nutrient reductions in the short term were primarily the result of the less‐than‐average precipitation and, consequently, streamflow that was 36% below normal. Therefore, nutrient concentrations measured in tributary streams were likely less than normal during the implementation period. Northern Missouri streamflow‐normalized TN concentrations remained relatively flat or declined over the period 1991 through 2013 likely because available sources of nitrogen, determined as the sum of commercial fertilizers, available animal manures and atmospheric inputs, were typically less than crop requirement for much of that time frame. Conversely, flow‐normalized stream TP concentrations increased over the past 22 years in northern Missouri streams, likely in response to many years of phosphorus inputs in excess of crop requirements. Stream nutrient changes were most pronounced during periods that coincided with the major tillage, planting and growth phases of row crops and increased streamflow. Nutrient reduction strategies targeted at the period February through June would likely have the greatest impact on reducing nutrient export from the basin. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.
- Assessing Juvenile Native Fish Demographic Responses to a Steady Flow
Experiment in a Large Regulated River
- Authors: C. Finch; W. E. Pine, C. B. Yackulic, M. J. Dodrill, M. Yard, B. S. Gerig, L. G. Coggins, J. Korman
Abstract: The Colorado River below Glen Canyon Dam, Arizona, is part of an adaptive management programme which optimizes dam operations to improve various resources in the downstream ecosystem within Grand Canyon. Understanding how populations of federally endangered humpback chub Gila cypha respond to these dam operations is a high priority. Here, we test hypotheses concerning temporal variation in juvenile humpback chub apparent survival rates and abundance by comparing estimates between hydropeaking and steady discharge regimes over a 3‐year period (July 2009–July 2012). The most supported model ignored flow type (steady vs hydropeaking) and estimated a declining trend in daily apparent survival rate across years (99.90%, 99.79% and 99.67% for 2009, 2010 and 2011, respectively). Corresponding abundance of juvenile humpback chub increased temporally; open population model estimates ranged from 615 to 2802 individuals/km, and closed model estimates ranged from 94 to 1515 individuals/km. These changes in apparent survival and abundance may reflect broader trends, or simply represent inter‐annual variation. Important findings include (i) juvenile humpback chub are currently surviving and recruiting in the mainstem Colorado River with increasing abundance; (ii) apparent survival does not benefit from steady fall discharges from Glen Canyon Dam; and (iii) direct assessment of demographic parameters for juvenile endangered fish are possible and can rapidly inform management actions in regulated rivers. Copyright © 2015 John Wiley & Sons, Ltd.
- Fish Associations among Un‐notched, Notched and L‐head Dikes
in the Middle Mississippi River
- Authors: Andrew P. Braun; Molly J. Sobotka, Quinton E. Phelps
Abstract: Wing dikes and other anthropogenic modifications have heavily altered riverine ecosystems. Recent efforts to reach a compromise between the needs of the river transportation industry and natural resource conservation include dike modification. Dike notching permits water flow through the landward portion of the dike and has been purported to provide suitable habitat for fish and other river biota while maintaining the navigation channel. L‐head dikes are flow‐control structures that create calm backwater‐like habitats downstream. However, few researchers have examined the actual effects of dike notching on water quality or fish communities. We compared standardized catch per unit effort and overall community structure for 50 fish species among un‐notched dikes, notched dikes and L‐head dikes in the Middle Mississippi River, sampled as part of the US Geological Survey's Long‐Term Resource Monitoring Program. There were no differences in standardized catch per unit effort for 64% of the fishes examined. Five species known to be associated with lotic habitats were most abundant near L‐head dikes. Seven species were more abundant at un‐notched dikes than notched dikes, while six species were more abundant at notched dikes than un‐notched dikes. Non‐metric multidimensional scaling suggested differences in overall fish community structure between un‐notched and other dike types. Detailed physical habitat studies should be conducted to better understand the effects of dike modification. Copyright © 2015 John Wiley & Sons, Ltd.
- Community Structure of Age‐0 Fishes in Paired Mainstem and Created
Shallow‐water Habitats in the Lower Missouri River
- Authors: T. A. Starks; J. M. Long, A. R. Dzialowski
Abstract: Anthropogenic alterations to aquatic ecosystems have greatly reduced and homogenized riverine habitat, especially those used by larval and juvenile fishes. Creation of shallow‐water habitats is used as a restoration technique in response to altered conditions in several studies globally, but only recently in the USA. In the summer of 2012, the U.S. Army Corps of Engineers sampled larval and juvenile fishes at six paired sites (mainstem and constructed chute shallow‐water habitats) along a section of the Missouri River between Rulo, NE and St. Louis, MO, USA. From those samples, we enumerated and identified a total of 7622 fishes representing 12 families. Community responses of fishes to created shallow‐water habitats were assessed by comparisons of species richness and diversity measures between paired sites and among sampling events. Shannon entropy measures were transformed, and gamma diversity (total diversity) was partitioned into two components, alpha (within community) and beta (between community) diversity using a multiplicative decomposition method. Mantel test results suggest site location, time of sampling event and habitat type were drivers of larval and juvenile community structure. Paired t‐test results indicated little to no differences in beta diversity between habitat types; however, chute habitats had significantly higher alpha and gamma diversity as well as increased abundances of Asian carp larvae when compared with mainstem shallow‐water habitat. Our results not only show the importance of created shallow‐water habitat in promoting stream fish diversity but also highlight the role space and time may play in future restoration and management efforts. Copyright © 2015 John Wiley & Sons, Ltd.
- Is Shallow Water a Suitable Surrogate for Assessing Efforts to Address
Pallid Sturgeon Population Declines?
- Authors: T. R. Gemeinhardt; N. J. C. Gosch, D. M. Morris, M. L. Miller, T. L. Welker, J. L. Bonneau
Abstract: It is hypothesized that slow, shallow water habitats benefit larval pallid sturgeon Scaphirhynchus albus; however, testing this hypothesis is difficult, given the low number of larval pallid sturgeon present in large rivers. In contrast, relatively large numbers of age‐0 shovelnose sturgeon Scaphirhynchus platorynchus have been sampled, providing a potentially useful baseline to assess the importance of slow, shallow water to age‐0 sturgeon of both species (hereafter age‐0 sturgeon) in the lower Missouri River. Thus, we investigated the potential relationships between the prevalence of shallow water 1.5 m, and catch rates were usually highest in the upper half [i.e. river kilometre (RKM) 400 to 800] of the lower Missouri River study area, whereas the availability of water
- Evaluation of Steelhead Passage Flows Using Hydraulic Modeling on an
Unregulated Coastal California River
- Authors: R. W. Holmes; D. E. Rankin, E. Ballard, M. Gard
Abstract: Passage and habitat connectivity flows for steelhead Oncorhynchus mykiss through depth sensitive natural, low gradient, critical riffle sites were investigated in the unregulated Big Sur River, California. The River2D two‐dimensional hydraulic habitat model, along with quantitative passage metrics and species‐specific and lifestage‐specific depth criteria, were used to evaluate and compare predicted fish passage flows with flows derived by a traditional empirical critical riffle fish passage method. Passage flows were also compared with historical unimpaired natural hydrology patterns to assess the frequency and duration of suitable passage flows under the naturally variable flow regimes characteristic of Central California coastal rivers. A strong relationship (r2 = 0.93) was observed between flows predicted by hydraulic modeling and flows identified by the empirical critical riffle method. River2D provided validation that the flows derived using the traditional critical riffle methodology provided for contiguous passable pathways of suitable hydraulic (depth and velocity) conditions through complex cobble‐dominated riffle sites. Furthermore, steelhead passage flows were spatially and temporally consistent between lagoon and upstream riffles for adults, and were generally indicative of a river system in equilibrium with a naturally variable flow regime and associated intact ecological processes. An analysis of 25 years of continuous flow data indicated sufficient flows for upstream passage by young‐of‐year and juvenile steelhead were produced between 37% and 100% and between 1% and 95% of the time, respectively. September and October are the most challenging months for natural flows to meet young‐of‐year and juvenile passage and habitat connectivity flows. Careful consideration of seasonal and interannual flow variability dynamics, therefore, are critical components of an effective flow management strategy for the maintenance and protection of passage and habitat connectivity flows between lagoon and upriver habitats. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.
- Diel Activity Patterns of Juvenile Late Fall‐run Chinook Salmon with
Implications for Operation of a Gated Water Diversion in the
Sacramento–San Joaquin River Delta
- Authors: J. M. Plumb; N. S. Adams, R. W. Perry, C. M. Holbrook, J. G. Romine, A. R. Blake, J. R. Burau
Abstract: In the Sacramento–San Joaquin River Delta, California, tidal forces that reverse river flows increase the proportion of water and juvenile late fall‐run Chinook salmon diverted into a network of channels that were constructed to support agriculture and human consumption. This area is known as the interior delta, and it has been associated with poor fish survival. Under the rationale that the fish will be diverted in proportion to the amount of water that is diverted, the Delta Cross Channel (DCC) has been prescriptively closed during the winter out‐migration to reduce fish entrainment and mortality into the interior delta. The fish are thought to migrate mostly at night, and so daytime operation of the DCC may allow for water diversion that minimizes fish entrainment and mortality. To assess this, the DCC gate was experimentally opened and closed while we released 2983 of the fish with acoustic transmitters upstream of the DCC to monitor their arrival and entrainment into the DCC. We used logistic regression to model night‐time arrival and entrainment probabilities with covariates that included the proportion of each diel period with upstream flow, flow, rate of change in flow and water temperature. The proportion of time with upstream flow was the most important driver of night‐time arrival probability, yet river flow had the largest effect on fish entrainment into the DCC. Modelling results suggest opening the DCC during daytime while keeping the DCC closed during night‐time may allow for water diversion that minimizes fish entrainment into the interior delta. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.
- Scaling Down Habitat Selection by Large River Fishes to Understand
Patterns Relevant to Individuals
- Authors: W. D. Hintz; G. T. Grimes, J. E. Garvey
Abstract: Modification and homogenization of habitat in large‐river ecosystems have led to the reduction of >50% of native fish species. Rehabilitating these complex ecosystems to recover fish populations requires an understanding of habitat availability and selection at multiple scales. Habitat selection by river fishes is typically assessed at the functional unit scale (100–10 000 m2). For example, in large, sand‐dominated rivers of the Central USA, alluvial islands are critical functional units for endangered sturgeon. Functional units, however, can be subdivided into mesohabitats (
- Juvenile Salmonid Utilization of Floodplain Rearing Habitat After Gravel
Augmentation in a Regulated River
- Authors: K. L. Sellheim; C. B. Watry, B. Rook, S. C. Zeug, J. Hannon, J. Zimmerman, K. Dove, J. E. Merz
Abstract: Gravel augmentation is used in sediment‐starved streams to improve salmonid spawning habitat. As gravel is added to river channels, water surface elevations may rise in adjacent areas, activating floodplain habitat at lower flows, and floodplains inundate more frequently, potentially affecting the quantity and quality of juvenile salmonid rearing habitat. We analysed 5 years of juvenile Chinook salmon Oncorhynchus tschawytscha and steelhead Oncorhynchus mykiss data from snorkel surveys before and after gravel augmentation in the Lower American River, a low‐gradient, highly regulated alluvial river in California's Central Valley. We measured the quality and quantity of rearing habitat (current velocity and areal extent of inundated riparian vegetation) following gravel placement and tested whether these factors affected juvenile abundance. Gravel augmentation increased floodplain extent by 3.7–19.8%, decreased average flow velocity from 1.6 to 0.3 m s−1 and increased the amount of vegetative cover from 0.3% to 22.6%. Juvenile abundances increased significantly for both species following augmentation. However, the strength of the relationship between abundance and habitat variables was greater for smaller salmonids. These results suggest that, in addition to enhancing salmonid spawning habitat, gravel augmentation can improve rearing habitat where channel incision and/or regulated hydrographs disconnect floodplains from main river channels. Copyright © 2015 John Wiley & Sons, Ltd.
- Environmental Factors Influencing Macrophytes Assemblages in a
Middle‐Sized Mediterranean Stream
- Authors: P. Manolaki; E. Papastergiadou
Abstract: The occurrence of aquatic plants was analysed in a medium‐sized river in Greece. There were three objectives. The first was to examine the macrophyte assemblage structure along the river. The identification and hierarchical structure of aquatic plant assemblages were analyzed using Bray–Curtis analysis. Taxa primarily responsible for the differences among the assemblages were identified using similarity percentage analysis. The second objective was to investigate whether habitat features have greater impact on aquatic plant assemblages than chemical parameters. Partial canonical correspondence analysis was used for partitioning the total variation of the biological response. The third objective was to further explore the relationships between hydrophytes (water‐supported plants) richness and water quality using linear regression model.
The results showed that from the 86 macrophyte taxa recorded, the 25 were found to be primarily responsible for the differences among the macrophytic assemblages. Both geomorphological and physicochemical variables proved to be significant in the Monte Carlo permutation test. The 14 out of 19 geomorphological variables were statistically significant (p
- DOWNSTREAM MIGRATION OF THE EUROPEAN EEL (ANGUILLA ANGUILLA) IN THE ELBE
RIVER, GERMANY: MOVEMENT PATTERNS AND THE POTENTIAL IMPACT OF
- Authors: F. Stein; P. Doering‐Arjes, E. Fladung, U. Brämick, B. Bendall, B. Schröder
Abstract: Recruitment of European eels (Anguilla anguilla) has declined to the extent that they have been added to the IUCN Red List of Threatened Species. Therefore, it is critical to ensure that eels complete their outward river migration in order to contribute to the available spawning stock. We conducted a 4‐year (2007–2011) telemetry study to understand the migratory behaviour and potential impact of environmental factors on the eel during this critical life stage.
Out of 399 female eels tagged with acoustic transmitters, only 28% demonstrated clear downstream migratory behaviour. Fifty‐five percent were detected exhibiting no downstream migration behaviour and 17% were not detected at any monitoring station. Movement patterns of downstream‐migrating (silver) eels were characterized by nocturnal activity and seasonal migration, with distinct peaks in autumn and spring. Migration was often discontinuous and exhibited phases of active locomotion and expanded stopovers. The most important determinants of movement activity were water temperature, cumulative precipitation and moonlight, although the significance varied by season and location in the river basin.
Our results evidence a discontinuous, stepwise migration over an extended period. Furthermore, our findings indicate that migration success depends on holding duration prior to tagging and environmental predictors with varying importance depending on the season, as well as the locations of capture, tagging and release. Copyright © 2015 John Wiley & Sons, Ltd.
- FISH ASSEMBLAGE STRUCTURE AND HABITAT ASSOCIATIONS IN A LARGE WESTERN
- Authors: C. D. Smith; M. C. Quist, R. S. Hardy
Abstract: Longitudinal gradients of fish assemblage and habitat structure were investigated in the Kootenai River of northern Idaho. A total of 43 500‐m river reaches was sampled repeatedly with several techniques (boat‐mounted electrofishing, hoop nets and benthic trawls) in the summers of 2012 and 2013. Differences in habitat and fish assemblage structure were apparent along the longitudinal gradient of the Kootenai River. Habitat characteristics (e.g. depth, substrate composition and water velocity) were related to fish assemblage structure in three different geomorphic river sections. Upper river sections were characterized by native salmonids (e.g. mountain whitefish Prosopium williamsoni), whereas native cyprinids (peamouth Mylocheilus caurinus, northern pikeminnow Ptychocheilus oregonensis) and non‐native fishes (pumpkinseed Lepomis gibbosus, yellow perch Perca flavescens) were common in the downstream section. Overall, a general pattern of species addition from upstream to downstream sections was discovered and is likely related to increased habitat complexity and additions of non‐native species in downstream sections. Assemblage structure of the upper sections were similar, but were both dissimilar to the lower section of the Kootenai River. Species‐specific hurdle regressions indicated the relationships among habitat characteristics and the predicted probability of occurrence and relative abundance varied by species. Understanding fish assemblage structure in relation to habitat could improve conservation efforts of rare fishes and improve management of coldwater river systems. Copyright © 2015 John Wiley & Sons, Ltd.
- THE ROLE OF RESERVOIRS IN SHAPING THE DOMINANT CYCLICITY AND ENERGY OF
MOUNTAIN RIVER FLOWS
- Authors: M. Kędra; Ł. Wiejaczka, K. Wesoły
Abstract: The main objective of the paper is to determine the role of mountain reservoirs in shaping the dominant cyclicity and energy of river flows. The paper compares a large complex composed of two reservoirs (Czorsztyn–Sromowce Wyżne) with a smaller reservoir (Besko). These reservoirs are located in the Polish Carpathians and are characterised by very different parameters and functions. Moreover, they operate on rivers (the Dunajec and the Wisłok) with different hydrologic regimes. Using Fourier spectral analysis of daily inflows, outflows and water levels in reservoirs for the period 1998–2012, it has been possible to identify the dominant frequencies of the considered time series with a percentage of spectral energy for these frequencies. Moreover, for signals created by river flow rates, changes in signal energy are associated with adequate changes in river energy. Therefore, by calculating the energy of the signal in the time domain, changes in signal energy can be observed before and after the water passes through the reservoir. Data on cyclicity of water levels in these reservoirs forms the background to the analysis of reservoir‐induced changes in cyclicity of river flows. The conducted analysis revealed that reservoirs strengthen the regularity of the annual periodicity of stream flow in the studied rivers. Besides, these reservoirs significantly reduce the energy of water flowing out of them compared to the energy of inflow. Copyright © 2015 John Wiley & Sons, Ltd.
- Structural Dynamics of Pristine Headwater Streams from Southern Brazilian
- Authors: M. E. Bleich; A. F. Mortati, T. André, M. T. F. Piedade
Abstract: Amazonian headwater streams trail a heterogeneous landscape, with marked natural variation of geomorphological conditions and hydrological periods. Southern Brazilian Amazon is subjected to high degradation pressure, mainly from deforestation. Hence, we characterize pristine headwaters structure (hydromorphology and water physical‐chemical variables) and variation among hydrological periods (dry, beginning of the rainy period and end of the rainy period), to define reference conditions for conservation‐oriented classification, monitoring and rehabilitation of the southern Brazilian Amazon streams. Stretches of 10 pristine streams from the Teles Pires River, a major tributary of the Tapajós River, were analysed for hydromorphology, water physical‐chemical variables and controlled for habitat integrity (forested proportion on buffer zones and habitat integrity index). We found variation among hydrological periods and spatial heterogeneity on pristine stream structure. Most variables showed great variation ranges at the same hydrological period and high variation coefficient values, reflecting the natural environmental heterogeneity among streams protected by a riparian forest. Variation among hydrological periods and spatial heterogeneity between streams in this region, combined with current high levels of deforestation, indicates the need for the conservation of a high proportion of streams and their respective riparian forests. Here, we have presented reference range values for monitoring and rehabilitation programs integrated in the Amazonian aquatic conservation efforts. Copyright © 2015 John Wiley & Sons, Ltd.
- A Community‐Level, Mesoscale Analysis of Fish Assemblage Structure
in Shoreline Habitats of a Large River using Multivariate Regression Trees
- Authors: M. A. Wilkes; I. Maddock, O. Link, E. Habit
Abstract: The mesoscale (100–102 m) of river habitats has been identified as the scale that simultaneously offers insights into ecological structure and falls within the practical bounds of river management. Mesoscale habitat (mesohabitat) classifications for relatively large rivers, however, are underdeveloped compared with those produced for smaller streams. Approaches to habitat modelling have traditionally focused on individual species or proceeded on a species‐by‐species basis. This is particularly problematic in larger rivers where the effects of biological interactions are more complex and intense. Community‐level approaches can rapidly model many species simultaneously, thereby integrating the effects of biological interactions while providing information on the relative importance of environmental variables in structuring the community. One such community‐level approach, multivariate regression trees, was applied in order to determine the relative influences of abiotic factors on fish assemblages within shoreline mesohabitats of San Pedro River, Chile, and to define reference communities prior to the planned construction of a hydroelectric power plant.
Flow depth, bank materials and the availability of riparian and instream cover, including woody debris, were the main variables driving differences between the assemblages. Species strongly indicative of distinctive mesohabitat types included the endemic Galaxias platei. Among other outcomes, the results provide information on the impact of non‐native salmonids on river‐dwelling Galaxias platei, suggesting a degree of habitat segregation between these taxa based on flow depth. The results support the use of the mesohabitat concept in large, relatively pristine river systems, and they represent a basis for assessing the impact of any future hydroelectric power plant construction and operation. By combing community classifications with simple sets of environmental rules, the multivariate regression trees produced can be used to predict the community structure of any mesohabitat along the reach. Copyright © 2015 John Wiley & Sons, Ltd.
- A Multimetric Macroinvertebrate Index for the Implementation of the
European Water Framework Directive in French Guiana, East Amazonia
- Authors: N. Dedieu; S. Clavier, R. Vigouroux, P. Cerdan, R. Céréghino
Abstract: Neotropical, overseas regions of Europe are subjected to the same water policy objectives as the continental ones but were overlooked during recent developments of bioindicators that fulfil the Water Framework Directive guidelines. We designed a macroinvertebrate‐based multimetric index [Indice Biotique Macroinvertébrés de Guyane (IBMG)] to assess ecological health in remote headwater‐small streams of French Guiana, Europe's only overseas region of continental South America. Invertebrates were sampled at 95 sites including reference and impacted river reaches, following a standardized protocol. Among the 102 biological metrics calculated from site‐specific data, we selected metrics exhibiting the best trade‐off between high discrimination efficiency, low specificity, low redundancy and high stability under reference conditions. The IBMG is composed of two taxonomic richness‐based metrics, two abundance‐based metrics, one trait‐related metric and a diversity index (Shannon's entropy). Each metric was weighted by its discrimination efficiency. Using a test data set, we found that the IBMG was sensitive to the range of disturbances in French Guiana. Finally, comparing the IBMG with other indices developed in other neotropical countries reveals that, for several reasons, multimetric indices developed in the neotropics may perform well in the context of the data sets used to generate them but would certainly fail to be robust when used elsewhere. Copyright © 2015 John Wiley & Sons, Ltd.
- Effects of Three Consecutive Rotenone Treatments on the Benthic
Macroinvertebrate Fauna of the River Ogna, Central Norway
- Authors: G. Kjærstad; J. V. Arnekleiv, J. D. M. Speed
Abstract: The effects of piscicides on aquatic invertebrates are often studied after one treatment, even though piscicides may be repeatedly applied within river management. Here we investigate the impacts of repeated piscidie treatment on riverine benthic invertebrates. The River Ogna, Norway, was treated with rotenone three times over a 16‐month period. The two first treatments caused temporary density reduction of a few rotenone sensitive benthic invertebrate taxa. Effects of the third treatment were variable with some taxa unaffected while all Plecoptera, were locally extinct. The toxic effect of rotenone increases with water temperature and high water temperature (20 °C) combined with high rotenone concentration was probably the main reason why the benthic community in the third treatment was more negatively affected than during the two previous treatments (4 and 8 °C). Eight months after the treatment benthic densities had not reached pre‐treatment levels, but most taxa had recolonized the treated area within a year. Our data suggest that the severe effects of the third treatment were not influenced by the two former ones. This implies that the timing of piscicide treatment has a greater impact on the benthic invertebrate community than the number of treatments. Copyright © 2015 John Wiley & Sons, Ltd.
- Strategies for Water Quality Assessment: A Multiparametric Analysis of
Microbiological Changes in River Waters
- Authors: P. Boi; S. Amalfitano, A. Manti, F. Semprucci, D. Sisti, M. B. Rocchi, M. Balsamo, S. Papa
Abstract: River waters are classified worldwide in relation to their chemical quality status, which is assessed by the presence of inorganic and organic pollutants. Meanwhile, microbiological quality evaluations are based mainly on the occurrence of pathogens and faecal contaminants, which are indirectly retrieved by standard cultivation methods. In this study, the structural dynamics of a riverine bacterioplankton community were investigated through a quantitative single‐cell approach with the use of flow cytometry for the quantification of total, viable and active cells. Furthermore, catalyzed reporter deposition (CARD)‐FISH was used for the evaluation of Proteobacteria and Cytophaga–Flavobacteria bacterial classes. The aim was to identify the major cytometric and phylogenetic cell groups that most representatively reflect the physical and chemical changes occurring in an upland‐to‐lowland transect along a human‐impacted river (the Foglia River, Italy). The use of CARD‐FISH to obtain cell abundance measurements of specific taxonomic clusters enabled different microbial propagation dynamics along the river transects to be identified. Furthermore, our results highlighted that the multiparametric approach with flow cytometry produces basic microbiological parameters in a reasonable time span that is consistent with the requirements for an early warning monitoring strategy with respect to integrated riverine water quality assessments. Copyright © 2015 John Wiley & Sons, Ltd.
- ECO‐FRIENDLY COUNTERMEASURES FOR ENLARGED BASINS EROSION
- Authors: S. Pagliara; M. Palermo, R. Das
Abstract: Eco‐friendly hydraulic structures (such as block ramps, rock weirs and stepped gabion weir) are generally made of rocks placed in two or more layers on a sloped bed. They are usually used in mountainous rivers to control sediment transport. The downstream stilling basin plays an important role in terms of both energy dissipation and erosion control. In addition, a correct design of the downstream stilling basin can create an optimal habitat for fish species in the river. Therefore, in the present work, an attempt was made to control the scour depth downstream of a block ramp using rock structures. In particular, the analysis was focused on scour characteristics in the presence of a protected and enlarged downstream channel. Namely, an abrupt symmetrically enlarged channel was simulated downstream of block ramps. Eco‐friendly protection structures, such as rock sills, were tested to limit the erosive process. Rock sills were placed transversally at different longitudinal and vertical positions in the stilling basin and scour morphology variations were investigated. Experiments were carried out for two different ratios of the width of the channel to the width of the ramp and three different ramp slopes. Several scour morphologies were distinguished and classified. In addition, empirical relationships were derived, by which it is possible to estimate the main scour geometry characteristics. Copyright © 2015 John Wiley & Sons, Ltd.
- Small Weirs, Big Effects: Disruption of Water Temperature Regimes with
Hydrological Alteration in a Mediterranean Stream
- Authors: M.‐J. Bae; R. Merciai, L. Benejam, S. Sabater, E. García‐Berthou
Abstract: The effects of hydrological alterations on thermal regimes due to small water provisioning schemes are poorly understood. We studied the alteration of thermal regimes in a Mediterranean stream, where a weir and a water abstraction have been previously shown to severely affect the flow regime (e.g. frequency and duration of drought) and fish assemblage. Compared to non‐impacted sites, the daily water temperature was more variable downstream of the weir, where water flow was reduced and drying occurred every summer. However, water temperature variation was smaller in a nearby downstream site dominated by effluents from a wastewater treatment plant. In addition, compared to all other sites, the times of the day to reach minimum and maximum water temperatures were markedly different in this site receiving the wastewater plant effluents and occurred earlier in the day in the site below the weir. The relationships between air and water temperatures were tight downstream but became looser and anomalous at the sites affected by water abstraction and effluent inputs. Overall, our results show that water temperature regimes in small streams are abruptly disrupted with water provisioning schemes with unknown consequences for aquatic organisms and ecosystems. Effects may be particularly stressful in Mediterranean‐climate streams, where water is scarce and hydrological alterations pervasive. Copyright © 2015 John Wiley & Sons, Ltd.
- SPAWNING MIGRATION OF WILD AND SUPPLEMENTARY STOCKED LANDLOCKED ATLANTIC
SALMON (SALMO SALAR)
- Authors: A. Hagelin; O. Calles, L. Greenberg, J. Piccolo, E. Bergman
Abstract: Upstream migration by adult salmonids is impeded by dams in many regulated rivers, as is the case for landlocked Atlantic salmon, Salmo salar, in the River Klarälven, Sweden. There, the salmon cannot reach the spawning grounds due to the presence of eight dams. Hence, hatchery‐reared smolts are released downstream of the dams, and upstream migrating spawners are caught in a trap at the lowermost dam before transported by truck to the spawning grounds past the dams. To identify the spawning grounds and compare the behavior of wild and hatchery‐reared Atlantic salmon during upstream migration and spawning, 34 wild and 28 hatchery‐reared, radio‐tagged Atlantic salmon were followed during their spawning migration from August to October 2011. Half (50%) of the hatchery fish, but only 11,8% of the wild fish ended up as fallbacks, i.e. they migrated past the first downstream power station, and did not spawn. A significantly higher proportion (21.4%) of hatchery‐ reared salmon moved in an erratic way, with several up and down stream movements, when compared to the wild salmon (5.9%). When looking at the salmon that stayed in the river (exc. fallbacks), wild individuals exhibited a holding behavior (little or no movements before presumed spawning) more often (86.7%) than the reared ones (50%). The wild salmon also held position (and presumably spawned) for longer time (25.4 days) than the reared salmon (16.1 days). Reared salmon held position, on average, 10 km further upstream than wild salmon, passing the presumed best‐quality spawning habitat. The migration speed (average 17.4 km/day) between two logger stations did not differ between wild and reared fish or between sexes. Our results suggest that the reproductive success of hatchery‐reared Atlantic salmon is relatively low and their capacity as supplementary spawners to the wild population in the Klarälven, is probably small. Copyright © 2015 John Wiley & Sons, Ltd.