- 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.
- DRAG FORCES ON LARGE CYLINDERS
- Authors: Benoit Turcotte; Robert G. Millar, Marwan A. Hassan
Abstract: Introducing large woody debris into streams is a common practice in restoration projects. Beyond the complexity of flow patterns and sediment movements in streams where woody debris are found or placed, it seems that our understanding of the basic hydraulics of large roughness elements in small channels remains limited. Underestimating the drag force affecting large roughness elements can compromise the success of stream restoration projects. Results from a simple experimental setting confirm that drag force estimates based on approaches developed for small cylinders are not valid when applied to large cylinders. Indeed, the classic drag force equation that uses an empirical drag coefficient is found to significantly underestimate measured drag forces, even when corrected for the ‘blockage ratio’. In contrast, application of specific momentum can yield good estimates of the drag force. A dimensionless depth is defined in a 1D context as a function of the flow depth, critical flow depth and cylinder diameter. A cylinder is considered to be ‘large’ when this dimensionless depth is smaller than 2. In this instance, a relationship is established to estimate the upstream flow depth and the drag force acting on the cylinder. This research bridges the small roughness element theory widely recognized in hydraulic engineering with the theory applicable to large, flow controlling structures such as weirs. From a practical perspective, this research can be used to assist in the design of engineered large woody debris structures. Copyright © 2015 John Wiley & Sons, Ltd.
- IDENTIFYING TEMPERATURE THRESHOLDS ASSOCIATED WITH FISH COMMUNITY CHANGES
IN BRITISH COLUMBIA, CANADA, TO SUPPORT IDENTIFICATION OF TEMPERATURE
- Authors: E. A. Parkinson; E. V. Lea, M. A. Nelitz, J. M. Knudson, R. D. Moore
Abstract: We collected fish samples and measured physical habitat characteristics, including summer stream temperatures, at 156 sites in 50 tributary streams in two sampling areas (Upper Fraser and Thompson Rivers) in British Columbia, Canada. Additional watershed characteristics were derived from GIS coverages of watershed, hydrological and climatic variables. Maximum weekly average temperature (MWAT), computed as an index of summer thermal regime, ranged from 10 to 23 °C. High values of MWAT were associated with large, warm, low relief watersheds with a high lake influence. Measures of community similarity suggested that the fish community changed most rapidly through a lower transition zone at an MWAT of about 12 °C and an upper transition zone at an MWAT of about 19 °C. These results were confirmed using existing fisheries inventory data combined with predictions of MWAT from a landscape‐scale regression model for the Thompson River watershed. For headwater sites in the Chilcotin River watershed (which drains into the middle Fraser River), the relative dominance of bull trout versus rainbow trout (based on inventory data) decreased with increasing predicted MWAT although the distinction was not as clear as for the Thompson River sites. The fish communities in these watersheds can be characterized in terms of very cold water (bull trout and some cold water species), cold water (salmonids and sculpins) and cool water (minnows and some cold water salmonids). The two transition zones (ca 12 and 19 °C) can be used to identify thresholds where small changes in stream temperature can be expected to lead to large changes in fish communities. Such clear, quantifiable thresholds are critical components of a management strategy designed to identify and protect vulnerable fish communities in streams where poor land use practices, alone or in combination with climatic change, can lead to changes in stream temperatures. Copyright © 2015 John Wiley & Sons, Ltd.
- RE‐OPERATING THE THREE GORGES RESERVOIR FOR ENVIRONMENTAL FLOWS: A
PRELIMINARY ASSESSMENT OF TRADE‐OFFS
- Authors: D. E. Rheinheimer; P. Liu, S. Guo
Abstract: The Three Gorges Reservoir (TGR), located on the Yangtze River in China, is operated for hydropower, flood control and navigation, with minimal environmental releases. This study explored the potential trade‐offs between better environmental releases from the TGR and hydropower generation using three performance indicators. Spearman's rank correlation coefficient between unimpaired flows and regulated flows was used as an indicator of environmental performance (eco rho). Energy generation as a fraction of capacity (energy fraction) and power reliability were used as hydropower performance indicators. We first assessed TGR performance without and with basic instream flow requirements (IFRs). We then imposed an IFR consisting of a minimum release of fraction k of inflow and maximum release of 1/k of inflow and assessed the sensitivity of reservoir performance to different fixed k values. Finally, we allowed k to vary within the year in a genetic algorithm to estimate the Pareto optimal trade‐offs between performance indicators. In all cases, flood and navigation rules were prioritized over environmental and hydropower. With a fixed k of 1.0, eco rho increased from 0.865 to nearly 1.0 (completely natural). Energy fraction reduced from 43.5 to 39.3%, or about 9.5%, and power reliability decreased from 97.0 to 59.2%. The Pareto optimal trade‐off surface not only showed similar results but also indicated that energy fraction and environmental performance can both be increased together, up to a point, but at a cost of reliability. This study helps understand the potential costs of re‐operating the TGR. Limitations and potential future directions are discussed. Copyright © 2015 John Wiley & Sons, Ltd.
- A Landscape‐Based Regionalization of Natural Flow Regimes in the
Ebro River Basin and its Biological Validation
- Authors: M. A. Solans; A. Mellado‐Díaz
Abstract: Flow prediction in ungauged basins is an important task for water resources planning and management, and remains a fundamental challenge for hydroecological research. Based on a previous classification of streams and rivers in the Ebro River basin (Spain), where six natural flow‐regime types were identified, we apply a new predictive approach of the flow regime type based on climatic and physiographic descriptors. We used a set of easily available environmental variables as discriminant parameters: annual precipitation, annual evapotranspiration, annual air temperature, elevation, catchment area, drainage density and geology. A stepwise landscape‐based classification procedure consisting of several stepwise discriminant analyses and canonical discriminant analyses allocated a set of sites with poor or no natural flow data into the flow types defined. Misclassification rates obtained by cross‐validation ranged between 1.12% and 11.9%. Additionally, the ecological soundness of the proposed regionalization was tested by the concordance between macroinvertebrate communities and the proposed classification using NMDS and ANOSIM. NMDS resulted in a clear separation of sites into five NFR classes with available macroinvertebrate data, and ANOSIM found significant differences in macroinvertebrate communities among classes. Copyright © 2015 John Wiley & Sons, Ltd.
- Process, Policy, and Implementation of Pool‐Wide Drawdowns on the
Upper Mississippi River: A Promising Approach for Ecological Restoration
of Large Impounded Rivers
- Authors: K. P. Kenow; G. L. Benjamin, T. W. Schlagenhaft, R. A. Nissen, M. Stefanski, G. J. Wege, S. A. Jutila, T. J. Newton
Abstract: The Upper Mississippi River (UMR) has been developed and subsequently managed for commercial navigation by the U.S. Army Corps of Engineers (USACE). The navigation pools created by a series of lock and dams initially provided a complex of aquatic habitats that supported a variety of fish and wildlife. However, biological productivity declined as the pools aged. The River Resources Forum, an advisory body to the St. Paul District of the USACE, established a multiagency Water Level Management Task Force (WLMTF) to evaluate the potential of water level management to improve ecological function and restore the distribution and abundance of fish and wildlife habitat. The WLMTF identified several water level management options and concluded that summer growing season drawdowns at the pool scale offered the greatest potential to provide habitat benefits over a large area. Here we summarize the process followed to plan and implement pool‐wide drawdowns on the UMR, including involvement of stakeholders in decision making, addressing requirements to modify reservoir operating plans, development and evaluation of drawdown alternatives, pool selection, establishment of a monitoring plan, interagency coordination, and a public information campaign. Three pool‐wide drawdowns were implemented within the St. Paul District and deemed successful in providing ecological benefits without adversely affecting commercial navigation and recreational use of the pools. Insights are provided based on more than 17 years of experience in planning and implementing drawdowns on the UMR. Copyright © 2015 John Wiley & Sons, Ltd.
- Anticipatory Management for Instream Habitat: Application to Carneros
- Authors: J. R. Beagle; G. M. Kondolf, R. M. Adams, L. Marcus
Abstract: Ecological research increasingly demonstrates that the best fish habitat is associated with complex, dynamically migrating channels. Active erosion and deposition create pools, side channels, and surfaces for recruitment of riparian vegetation, resulting in hydraulic complexity. As such, the most effective and sustainable restoration strategies restore natural processes, and in turn, create biological habitat. Nevertheless, there exists a social–cultural preference for stable channels. Landowners are often unhappy with eroding banks and, more broadly, are uncomfortable with ‘messy’ ecosystems and the erosion, deposition, and channel migration that are essential components of the dynamic channels that provide the greatest floodplain biodiversity. Episodic bank erosion and failure are often treated with emergency response measures, such as riprap and bank hardening. This often results in simplified channels with minimized instream habitat. Here, we propose an alternative management approach for streams with cohesive banks, and where active erosion is concentrated in ‘hot spots’ that are roughly predictable based on geomorphic analysis. We term the approach anticipatory management and present an application of the approach to Carneros Creek, an incised tributary to the Napa River. We contrast the likely habitat values and agricultural land loss of the anticipatory management approach to: (i) a conventional bank stabilization project proposed for the creek, and (ii) a series of uniform setbacks. Copyright © 2015 John Wiley & Sons, Ltd.
- Ecofriendly River Management under Ever‐Increasing Environmental
- Authors: X. A. Yin; G. E. Petts, Z. F. Yang
Pages: 403 - 405
Abstract: The third biennial symposium of the International Society for River Science was held at Beijing Normal University, China, on 5–9 August 2013. The symposium was dedicated to consolidating knowledge on riverine ecosystem in response to the impacts of ever‐increasing environmental pressures and promoting multi‐disciplinary solutions for protecting and restoring ecosystems. Nine papers were selected to illustrate advances in understanding the mechanisms of ecological degradation, promoting new models for simulating the hydrological and ecological processes and establishing new tools for ecofriendly water resources management. Copyright © 2015 John Wiley & Sons, Ltd.
- OPTIMAL FISH PASSAGE BARRIER REMOVAL—REVISITED
- Authors: S. King; J. R. O'Hanley
Abstract: Infrastructure, such as dams, weirs and culverts, disrupt the longitudinal connectivity of rivers, causing adverse impacts on fish and other aquatic species. Improving fish passage at artificial barriers, accordingly, can be an especially effective and economical river restoration option. In this article, we propose a novel, mixed integer programing model for optimizing barrier mitigation decisions given a limited budget. Rather than simply treating barriers as being impassable or not, we consider the more general case in which barriers may be partially passable. Although this assumption normally introduces nonlinearity into the problem, we manage to formulate a linear model via the use of probability chains, a newly proposed technique from the operations research literature. Our model is noteworthy in that it can be readily implemented and solved using off‐the‐shelf optimization modelling software. Using a case study from the US State of Maine, we demonstrate that the model is highly efficient in comparison with existing solution methods and, moreover, highly scalable in that large problems with many thounsands of barriers can still be solved optimally. Our analysis confirms that barrier mitigation can provide substantial ecological gains for migratory fish at low levels of investment. Copyright © 2014 John Wiley & Sons, Ltd.
- Synthesizing Environmental Flow Needs Data for Water Management in a
Water‐Scarce State: The Arizona Environmental Water Demands Database
- Authors: K. E. Mott Lacroix; B. C. Xiu, J. B. Nadeau, S. B. Megdal
Abstract: Water rights for environmental flows are not universal, and oftentimes, legal tools used to incorporate the environment into water management only require new users to consider their impact. It can be difficult to include the needs of riparian and aquatic ecosystems in new plans when relevant information is not always available, especially when other existing uses already outstrip available supplies. There is a need for easily accessible and understandable science on the water requirements for riparian and aquatic species, so managers can make informed decisions about whether or not to include riparian and aquatic species in their community's water management future. In this paper, we describe the current understanding of the link between hydrology and Arizona's riparian and aquatic ecosystems through the creation of a geospatial Environmental Water Demands database that can be used to determine the water needs to maintain habitat. Analysis of 121 studies reveals that there are very few analyses of the surface water and groundwater requirements for intermittent or ephemeral river systems, and there are only limited generalizable data for aquatic species. Except for a few species, such as Cottonwood (Populous fremontii) and Willow (Salix gooddingii), few data are available on the flow requirements for vegetation. The Environmental Water Demands database can be used to identify critical geographic and topical knowledge gaps where further research is needed, as well as serve as a single place for water and land managers to assess and use the most currently available information to make more informed management decisions and recommendations. Copyright © 2014 John Wiley & Sons, Ltd.
- A TEST OF THE SERIAL DISCONTINUITY CONCEPT: LONGITUDINAL TRENDS OF BENTHIC
INVERTEBRATES IN REGULATED AND NATURAL RIVERS OF NORTHERN CANADA
- Authors: L. E. Ellis; N. E. Jones
Abstract: Abiotic and biotic impacts below impoundments within the context of the River Continuum (RCC) and the Serial Discontinuity Concepts (SDC) have been the focus of many lotic studies. Recovery gradients, however, are rarely examined in sufficient detail below dams. Further refinement and understanding are needed to inform science and river managers about regulated river ecology. In this study, we examine longitudinal patterns in abiotic and biotic characteristics in two regulated rivers in Northern Canada. We also examine spatial patterns on two natural rivers: a lake outlet river and a river with no lakes. Direct gradient analysis revealed that increases in periphyton, planktonic drift, primary production, substrate size, and changes in thermal regime at sites closest to the dam drive benthic invertebrate community characteristics. We test the Serial Discontinuity Concept by comparing predicted functional forms of each environmental variable with the empirically derived forms. Substrate size, periphyton biomass, and drift density increased below dams and recovered quickly within 5 km downstream, following closely with SDC predictions. The response of organic matter and water quality was variable, and benthic invertebrate richness recovered relatively quickly, contrary to SDC predictions. Thermal regime and flow took much longer to recover than most variables and represent a second longer gradient type below dams. Plecoptera, Gomphidae, and Simuliidae were strongly influenced by altered resource and habitat and may be good candidates for indicators and predictive modelling. Our results generally support predictions from the Serial Discontinuity Concept and highlight the need for the further testing and refinement of this concept. Copyright © 2014 John Wiley & Sons, Ltd.
- SURVIVAL, GROWTH, AND MOVEMENT OF SUBADULT HUMPBACK CHUB, GILA CYPHA, IN
THE LITTLE COLORADO RIVER, ARIZONA
- Authors: M. C. Dzul; C. B. Yackulic, D. M. Stone, D. R. Van Haverbeke
Abstract: Ecologists estimate vital rates, such as growth and survival, to better understand population dynamics and identify sensitive life history parameters for species or populations of concern. Here, we assess spatiotemporal variation in growth, movement, density, and survival of subadult humpback chub living in the Little Colorado River, Grand Canyon, AZ from 2001–2002 and 2009–2013. We divided the Little Colorado River into three reaches and used a multistate mark‐recapture model to determine rates of movement and differences in survival and density between sites for different cohorts. Additionally, site‐specific and year‐specific effects on growth were evaluated using a linear model. Results indicate that summer growth was higher for upstream sites compared with downstream sites. In contrast, there was not a consistent spatial pattern across years in winter growth; however, river‐wide winter growth was negatively related to the duration of floods from 1 October to 15 May. Apparent survival was estimated to be lower at the most downstream site compared with the upstream sites; however, this could be because in part of increased emigration into the Colorado River at downstream sites. Furthermore, the 2010 cohort (i.e. fish that are age 1 in 2010) exhibited high apparent survival relative to other years. Movement between reaches varied with year, and some years exhibited preferential upstream displacement. Improving understanding of spatiotemporal effects on age 1 humpback chub survival can help inform current management efforts to translocate humpback chub into new locations and give us a better understanding of the factors that may limit this tributary's carrying capacity for humpback chub. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
- IMPROVING ANN‐BASED SHORT‐TERM AND LONG‐TERM SEASONAL
RIVER FLOW FORECASTING WITH SIGNAL PROCESSING TECHNIQUES
- Authors: H. Badrzadeh; R. Sarukkalige, A. W. Jayawardena
Abstract: One of the key elements in achieving sustainable water resources and environmental management is forecasting the future condition of the surface water resources. In this study, the performance of a river flow forecasting model is improved when different input combinations and signal processing techniques are applied on multi‐layer backpropagation neural networks. Haar, Coiflet and Daubechies wavelet analysis are coupled with backpropagation neural networks model to develop hybrid wavelet neural networks models. Different models with different input selections and structures are developed for daily, weekly and monthly river flow forecasting in Ellen Brook River, Western Australia. Comparison of the performance of the hybrid approach with that of the original neural networks indicates that the hybrid models produce significantly better results. The improvement is more substantial for peak values and longer‐term forecasting, in which the Nash–Sutcliffe coefficient of efficiency for monthly river flow forecasting is improved from 0.63 to 0.89 in this study. Copyright © 2014 John Wiley & Sons, Ltd.
- LONG‐TERM DYNAMICS OF LARGE‐BODIED FISHES ASSESSED FROM
SPATIALLY INTENSIVE MONITORING OF A MANAGED DESERT RIVER
- Authors: N. R. Franssen; S. L. Durst, K. B. Gido, D. W. Ryden, V. Lamarra, D. L. Propst
Abstract: Imperilment of native fishes worldwide, and particularly in the American Southwest, has prompted management actions to protect and recover threatened populations. Implementation of management activities, however, often proceeds without clear understandings of ecological interactions between native fishes and other biotic and physical components of the environment. Using data obtained in a 19‐year, intensive monitoring effort across 288 km of the San Juan River in NM and UT, USA, we quantified relationships among large‐bodied fishes and longitudinal environmental gradients, tested for faunal breaks of fishes and habitat structure along the river's course, and assessed the response of fishes to mechanical removal of non‐native fishes and stocking of endangered fishes. Mesohabitat variation was not strongly linked to densities of large‐bodied fishes, but we found strong and temporally consistent longitudinal patterns of native and non‐native fishes: Native fish densities were highest upstream while non‐native fish densities where highest downstream, potentially driven by differential responses to temperature regimes. Two breaks in the longitudinal structure of large‐bodied fishes were identified and were associated with a man‐made barrier and changes in the width of the river's floodplain. While densities of common native fishes were relatively constant during the study, non‐native fish removal apparently reduced densities of one of two targeted species and densities of two endangered fishes increased as a result of stocking hatchery‐reared fish. Results of this study suggest that large‐bodied fishes of the San Juan River are responding to large‐scale longitudinal gradients rather than small‐scale habitat variation and management activities have altered densities of target species with limited responses by other fishes in the system. Copyright © 2014 John Wiley & Sons, Ltd.
- FATTY ACID PROFILES DISTINGUISH CHANNEL CATFISH FROM THREE REACHES OF THE
LOWER KASKASKIA RIVER AND ITS FLOODPLAIN LAKES
- Authors: M. P. Young; G. W. Whitledge, J. T. Trushenski
Abstract: Despite the increasing use of fatty acids (FAs) as biomarkers in aquatic food web analysis, little information is available regarding differences in FA profiles of fish among habitat types in river–floodplain ecosystems. The objectives of this study were to (i) test whether the FA profiles of channel catfish (Ictalurus punctatus) differed among three reaches of the lower Kaskaskia River and its floodplain lakes, and (ii) to compare FA profiles among muscle, liver, and adipose fin tissues collected from these fish. Profiles differed significantly among sites, especially between upper and lower river sites, and between river channel and oxbow lake sites, suggesting differences in FA availability for channel catfish occupying different habitats and river reaches in the Kaskaskia River system. Specifically, the essential FAs 18:2n‐6 and 18:3n‐3 increased in catfish tissues from upstream to downstream reaches, which could reflect increased floodplain connectivity and decreasing impoundment effects downstream. Ratios of n‐3 to n‐6 FAs were higher in fish from oxbow lakes, perhaps suggesting increased use of autochthonous production in the floodplain relative to the main river channel. Muscle and adipose fin FA profiles exhibited similar location‐related trends, whereas liver FA profiles were markedly different from the other tissue types. These results suggest that adipose fin tissue samples may be a viable, less‐invasive alternative to muscle tissue for analysis of FA profiles in channel catfish. Our study supports the use of tissue FA profiles in identifying habitat utilization by channel catfish, and perhaps habitat‐specific energy contributions to riverine consumers. Furthermore, our work highlights floodplain habitat as a potential source of essential n‐3 FA and the associated importance of maintaining river–floodplain connectivity to support aquatic food webs. Copyright © 2014 John Wiley & Sons, Ltd.
- NATURAL FLOW REGIMES OF THE OZARK–OUACHITA INTERIOR HIGHLANDS REGION
- Authors: D. R. Leasure; D. D. Magoulick, S. D. Longing
Abstract: Natural flow regimes represent the hydrologic conditions to which native aquatic organisms are best adapted. We completed a regional river classification and quantitative descriptions of each natural flow regime for the Ozark–Ouachita Interior Highlands region of Arkansas, Missouri and Oklahoma. On the basis of daily flow records from 64 reference streams, seven natural flow regimes were identified with mixture model cluster analysis: Groundwater Stable, Groundwater, Groundwater Flashy, Perennial Runoff, Runoff Flashy, Intermittent Runoff and Intermittent Flashy. Sets of flow metrics were selected that best quantified nine ecologically important components of these natural flow regimes. An uncertainty analysis was performed to avoid selecting metrics strongly affected by measurement uncertainty that can result from short periods of record. Measurement uncertainties (bias, precision and accuracy) were assessed for 170 commonly used flow metrics. The ranges of variability expected for select flow metrics under natural conditions were quantified for each flow regime to provide a reference for future assessments of hydrologic alteration. A random forest model was used to predict the natural flow regimes of all stream segments in the study area based on climate and catchment characteristics, and a map was produced. The geographic distribution of flow regimes suggested distinct ecohydrological regions that may be useful for conservation planning. This project provides a hydrologic foundation for future examination of flow–ecology relationships in the region. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
- POPULATION TRENDS, BEND USE RELATIVE TO AVAILABLE HABITAT AND
WITHIN‐RIVER‐BEND HABITAT USE OF EIGHT INDICATOR SPECIES OF
MISSOURI AND LOWER KANSAS RIVER BENTHIC FISHES: 15 YEARS AFTER BASELINE
- Authors: M. L. Wildhaber; W.‐H. Yang, A. Arab
Abstract: A baseline assessment of the Missouri River fish community and species‐specific habitat use patterns conducted from 1996 to 1998 provided the first comprehensive analysis of Missouri River benthic fish population trends and habitat use in the Missouri and Lower Yellowstone rivers, exclusive of reservoirs, and provided the foundation for the present Pallid Sturgeon Population Assessment Program (PSPAP). Data used in such studies are frequently zero inflated. To address this issue, the zero‐inflated Poisson (ZIP) model was applied. This follow‐up study is based on PSPAP data collected up to 15 years later along with new understanding of how habitat characteristics among and within bends affect habitat use of fish species targeted by PSPAP, including pallid sturgeon. This work demonstrated that a large‐scale, large‐river, PSPAP‐type monitoring program can be an effective tool for assessing population trends and habitat usage of large‐river fish species. Using multiple gears, PSPAP was effective in monitoring shovelnose and pallid sturgeons, sicklefin, shoal and sturgeon chubs, sand shiner, blue sucker and sauger. For all species, the relationship between environmental variables and relative abundance differed, somewhat, among river segments suggesting the importance of the overall conditions of Upper and Middle Missouri River and Lower Missouri and Kansas rivers on the habitat usage patterns exhibited. Shoal and sicklefin chubs exhibited many similar habitat usage patterns; blue sucker and shovelnose sturgeon also shared similar responses. For pallid sturgeon, the primary focus of PSPAP, relative abundance tended to increase in Upper and Middle Missouri River paralleling stocking efforts, whereas no evidence of an increasing relative abundance was found in the Lower Missouri River despite stocking. Copyright © 2014 John Wiley & Sons, Ltd.
- HISTORICAL CHANGES IN FISH ASSEMBLAGE COMPOSITION FOLLOWING WATER QUALITY
IMPROVEMENT IN THE MAINSTEM TRINITY RIVER OF TEXAS
- Authors: J. S. Perkin; T. H. Bonner
Abstract: The Clean Water Act of 1972 is credited with improving water quality across the USA, although few long‐term studies tracking hydrologic, chemical, and biological responses to cleanup efforts exist. The Trinity River of Texas was plagued by poor water quality for more than a century before passage of legislation to reduce point source pollution from the Dallas–Fort Worth (DFW) Metroplex. We tracked changes in components of flow regime; concentrations of ammonia, nitrate, phosphorus, and biochemical oxygen demand (BOD); and fish assemblage composition in three mainstem reaches during a 40‐year period (1968–2008) following implementation of a large‐scale cleanup initiative. Results suggest little change in flow regime components such as magnitude, timing, and rate of change among the three reaches during 1968–2008. Concentrations of water quality parameters declined through time and with greater distance from DFW, including the lowest concentrations in the reach downstream of a mainstem reservoir (Lake Livingston). Fish assemblage composition shifts correlated with attenuated nutrient and BOD concentrations, and species richness generally increased among all reaches. Native and intolerant fishes consistently increased through time among all three reaches, although lentic and non‐native species also increased downstream of Lake Livingston. Our findings suggest a revitalization of the Trinity River fish assemblage associated with reduced nutrient pollution in DFW (even among distant reaches) and also illustrate potential confounding factors such as stream impoundment and continued nutrient deposition that likely preclude complete recovery. Copyright © 2014 John Wiley & Sons, Ltd.
- AT‐A‐STATION HYDRAULIC GEOMETRY SIMULATOR
- Authors: Daniel John McParland; Brett Eaton, Jordan Rosenfeld
Abstract: Presented in this paper is a hydraulic model that combines a rational regime theory with an at‐a‐station hydraulic geometry simulator (ASHGS) to predict reach‐averaged hydraulic conditions for flows up to but not exceeding the bankfull stage. The hydraulic conditions determined by ASHGS can be paired with an empirical joint frequency distribution equation and applicable habitat suitability indices to generate weighted usable area (WUA) as a function of flow. ASHGS was tested against a 2‐dimensional hydrodynamic model (River2D) of a mid‐size channel in the Interior Region of British Columbia. By linking ASHGS to a regime model, it becomes possible to evaluate the direction and magnitude of habitat changes associated with a wide range of environmental changes. Our regime model considers flow regime, sediment supply, and riparian vegetation: these governing variables can be used to simulate responses to forest fire, flow regulation and changes in climate and land use. Practitioners can examine ‘what‐if’ scenarios that otherwise would be too expensive and time consuming to fully explore. The model boundaries of commonly used data‐intensive hydraulic habitat models (e.g. PHABSIM) are not easily adjusted and such models are not designed to estimate future morphological and hydraulic habitat conditions in rivers the undergo significant channel restructuring. The proposed model has the potential to become an accepted flow assessment tool amongst practitioners due to modest data requirements, user‐friendliness, and large spatial applicability; it can be used to conduct preliminary assessments of channel altering projects and determine if in‐depth habitat assessments are justified.
- AN ESTIMATE OF BASIN‐WIDE DENITRIFICATION BASED ON FLOODPLAIN
INUNDATION IN THE ATCHAFALAYA RIVER BASIN, LOUISIANA
- Authors: M. G. Bennett; K. A. Fritz, A. Hayden‐Lesmeister, J. P. Kozak, A. Nickolotsky
Abstract: Maximizing the reduction of nitrate to dinitrogen gas (denitrification) has been advocated as a means to decrease nitrate pollution that causes eutrophication and hypoxia in estuaries worldwide. Managing this flux in bottomland forest wetlands of the Mississippi River could potentially reduce the world's second largest hypoxic zone. We used published denitrification rates, geospatial data on habitat area and inundation frequency, water level records (1963–2011), and average monthly temperatures to estimate annual denitrification in the Atchafalaya River Basin, the principal distributary of the Mississippi River. Denitrification rates ranged from 5394 kg N year−1 (3.07 kg N km−2 year−1) in 1988 to 17 420 kg N year−1 (9.92 kg N km−2 year−1) in 1981, and rates were consistently higher in fall compared with those in spring. Total NO3− denitrified in the basin was negligible compared with total NO3− entering the Gulf of Mexico. If all N denitrified in the basin instead entered the Gulf, the hypoxic zone was predicted to increase only 5.07 km2 (0.06%). This negligible effect of the basin on N dynamics in the Gulf agrees with other mass balance and isotopic studies in the region. Copyright © 2014 John Wiley & Sons, Ltd.
- ECOSYSTEM MANAGEMENT ALONG EPHEMERAL RIVERS: TRADING OFF
SOCIO‐ECONOMIC WATER SUPPLY AND VEGETATION CONSERVATION UNDER FLOOD
- Authors: S. Arnold; S. Attinger, K. Frank, P. Baxter, H. Possingham, A. Hildebrandt
Abstract: In ecosystems driven by water availability, plant community dynamics depend on complex interactions between vegetation, hydrology, and human water resources use. Along ephemeral rivers—where water availability is erratic—vegetation and people are particularly vulnerable to changes in each other's water use. Sensible management requires that water supply be maintained for people, while preserving ecosystem health. Meeting such requirements is challenging because of the unpredictable water availability. We applied information gap decision theory to an ecohydrological system model of the Kuiseb River environment in Namibia. Our aim was to identify the robustness of ecosystem and water management strategies to uncertainties in future flood regimes along ephemeral rivers. We evaluated the trade‐offs between alternative performance criteria and their robustness to uncertainty to account for both (i) human demands for water supply and (ii) reducing the risk of species extinction caused by water mining. Increasing uncertainty of flood regime parameters reduced the performance under both objectives. Remarkably, the ecological objective (species coexistence) was more sensitive to uncertainty than the water supply objective. However, within each objective, the relative performance of different management strategies was insensitive to uncertainty. The ‘best’ management strategy was one that is tuned to the competitive species interactions in the Kuiseb environment. It regulates the biomass of the strongest competitor and, thus, at the same time decreases transpiration, thereby increasing groundwater storage and reducing pressure on less dominant species. This robust mutually acceptable strategy enables species persistence without markedly reducing the water supply for humans. This study emphasises the utility of ecohydrological models for resource management of water‐controlled ecosystems. Although trade‐offs were identified between alternative performance criteria and their robustness to uncertain future flood regimes, management strategies were identified that help to secure an ecologically sustainable water supply. Copyright © 2014 John Wiley & Sons, Ltd.
- HYDROLOGIC VARIABILITY INFLUENCES LOCAL PROBABILITY OF PALLID STURGEON
OCCURRENCE IN A MISSOURI RIVER TRIBUTARY
- Authors: M. J. Hamel; J. J. Spurgeon, M. A. Pegg, J. J. Hammen, M. L. Rugg
Abstract: A river's flow regime creates and maintains spatial variability in habitat and dictates the distribution and abundance of riverine fishes. Changes to patterns of natural hydrologic variation and disturbance create novel flow conditions and may influence distribution of native fishes. We examined local and regional‐scale factors that influenced the presence of pallid sturgeon Scaphirhynchus albus in the Platte River, a large tributary to the Missouri River in Nebraska, USA. Daily river discharge, diel flow variability, season and location in the study area were the most supported variables in logistic regression models explaining pallid sturgeon distribution. The probability of pallid sturgeon occurrence was greatest during periods of high discharge (>90th percentile flows) in the spring and fall. Pallid sturgeon occurrence was always lower when variability in diel flow patterns was high (i.e. hydropeaking). Our results indicate that pallid sturgeon use of the lower Platte River was strongly tied to the flow regime. Therefore, the lower Platte River may provide an opportunity to preserve and restore sturgeon and possibly other large‐river fishes through appropriate water management strategies. Copyright © 2014 John Wiley & Sons, Ltd.
- Using Google Earth, A Virtual‐Globe Imaging Platform, for Ecosystem
Services‐Based River Assessment
- Authors: A. R. G. Large; D. J. Gilvear
Pages: 406 - 421
Abstract: A methodology for reach‐based river ecosystem service assessment of eight ecosystem functions using remote sensing via Google Earth is presented. The number of publications addressing Google Earth and ecosystem services has grown significantly since 2005, yet this powerful remote sensing platform remains under‐used in river science. Theoretical linkages between 18 riverscape fluvial features, attributes and land cover types, observable and measurable on Google Earth, and resultant river ecosystem service delivery are central to the methodology. Using this framework, we build on earlier ecosystem service conceptual models to develop a rules‐based scoring approach and apply it to three rivers of differing size and character from source to mouth. The aim was to devise a robust ecosystem service assessment tool applicable to any ecoregion and to rivers of any size, degree of human modification and character. Reach or sector scales are river length dependent. The minimum reach scale recommended is 500 m, and a 10 km sector length was used on the longest of our three rivers. Two key metrics, the individual ecosystem service score and the total ecosystems service score, are derived at the river reach scale from source to mouth. Scoring is on a 0–3 scale with 0 representing an absent or virtually no ecosystem service value and 3 an optimal or maximum value. Output is best expressed in score per kilometre of river length. The exercise showed the tool to be applicable across two ecoregions and to rivers of varying size, level of human modification and character. While requiring further refinement, the approach shows that ecosystem service assessments based on virtual globes can be universally applied providing valuable information on riverscape ecosystem service delivery. Copyright © 2014 John Wiley & Sons, Ltd.
- Climate‐Induced Flow Regime Alterations and their Implications for
the Lancang River, China
- Authors: J. Tang; X. A. Yin, P. Yang, Z. F. Yang
Pages: 422 - 432
Abstract: Most studies of the Lancang River have focussed on the influence of hydropower generation on the riverine ecosystem. Few studies have explored climate‐induced flow regime alterations and their implications for the riverine ecosystem. There is a pressing need for improved understanding of the implications of such climate‐induced flow regime alterations in the Lancang River Basin. Future streamflow under the A2 and B2 scenarios of Hadley Centre coupled model version 3 (HadCM3) are predicted using a back propagation artificial neural network. Potential effects of flow regime alterations are tested by amended annual proportional flow deviation (AAPFD). Projected streamflow will decrease in wet season months and will increase in dry season months. Monthly streamflow at Jiuzhou station was projected to range from a 27.9% decrease to a 158.4% increase. For Gajiu station, the percent increase was projected to range from 1.4% to 70.4%, while the decrease ranged from 0.2% to 16.9%. Changes in streamflow at Yunjinghong station ranged from a 46.5% decrease to a 135.3% increase. Projected streamflow changes during high and low flow periods will have important implications for the ecological processes of the Lancang River Basin. AAPFD indicates that these changes will have serious effects on the Lancang River Basin ecosystem. Projected climate‐induced flow regime alterations during the period of 2071–2095 will have particularly serious effects on riverine ecosystem, especially in the upstream and downstream sections of the Lancang River. The A2 scenario will pose a more serious threat to riverine ecosystem health. Copyright © 2014 John Wiley & Sons, Ltd.
- The Survival of Atlantic Salmon (Salmo salar) Eggs During Dewatering in a
River Subjected to Hydropeaking
- Authors: R. Casas‐Mulet; S. J. Saltveit, K. Alfredsen
Pages: 433 - 446
Abstract: Hydropeaking in regulated rivers is likely to become more frequent with increasing demands for renewable energy. Sudden fluctuations affect surface and subsurface flow regimes and change hydrological interactions occurring in the hyporheic zone. The hyporheic zone plays an important role for salmon embryonic development, and groundwater influx may create refuges for egg survival during low flow in hydropeaking regulated rivers. The links between salmon embryo survival and hyporheic hydrological processes during hydropeaking have hardly been investigated.
A field experiment was undertaken in a 5 × 20 m side gravel bar subject to dewatering due to hydropeaking. Eleven cylindrical boxes composed of eight compartments were placed in the permanently wet area and the ramping zone. Sixty eggs were placed in two compartments (at 10 and 30 cm depth) in each box. Surface and interstitial water levels and temperatures were monitored at 2 min resolution. Data were collected for a period of 3 months, coinciding with early stages of salmonid egg development in this catchment. Egg compartments were checked on six occasions for survival after different hydropeaking events. Dead eggs were counted and removed. Survival rates were lower in the top compartments in the ramping zone (78%) compared with the boxes in the permanently wet area and the lowermost compartments in the ramping (survival rates >99%). With no water quality issues in the catchment and very low inputs of fine sediments in the egg compartments, exposure to dry conditions and subzero temperatures were the main factors explaining egg mortality in the top compartments of the ramping zone. The rate of survival will thus depend on the surface water and groundwater interactions. Site‐specific hydrological interactions occurring in the hyporheic zone should be actively considered when managing fish populations in rivers with hydropeaking. Copyright © 2014 John Wiley & Sons, Ltd.
- A Hybrid Lattice Boltzmann Method–Finite Difference Method Model for
Sediment Transport and Riverbed Deformation
- Authors: H. Liu; Y. Ding, M. Li, P. Lin, M. H. Yu, A. P. Shu
Pages: 447 - 456
Abstract: In this study, a two‐dimensional hybrid numerical model for sediment transport based on lattice Boltzmann method and finite difference method is presented. The governing equations for water flow and suspended sediment transport are the shallow water equations and the advection–diffusion equations, respectively. Sediment load is also involved, so that riverbed deformation is numerically simulated. The model is verified by testing transportation of bank‐slump sediment in a sharp bended channel with the comparison to the results of well‐accepted finite volume method, illustrating the effectiveness of the proposed hybrid model. Copyright © 2014 John Wiley & Sons, Ltd.
- Dynamic Modelling of Soil Nitrogen Budget and Vegetation Colonization in
Sediment Bars of a Regulated River
- Authors: T. Asaeda; M. H. Rashid, R. Abu Bakar
Pages: 470 - 484
Abstract: Intensive forestation widely occurs in East Asian rivers. It deteriorates the ecosystem of gravelly or sandy bars, affects flood protection, and changes the landscape of the river. For the regulation of forestation and vegetative succession on the bars, a suitable tool, through either a numerical simulation model or through empirical knowledge that will predict the future process after treatment, is required. With this background, a dynamic model is developed based on the empirical knowledge obtained by field observations in order to simulate the vegetative growth process on the bars. Observations were conducted at several Japanese rivers in order to better understand tree growth and biomass, herbaceous plant biomass, and soil nitrogen content. The model is composed of four modules: a hydrological module, which provides for flood inundation, flushing and sedimentation processes, a tree module, which describes the recruitment, growth and thinning of tree densities, and a herbaceous plant module, which describes the biomass of herbs as a function of environmental conditions. Finally, there is a soil module, which mostly describes nitrogen budgets. The model was successfully applied to the Arakawa River in central Japan in order to simulate a 30‐year process after a major flood. Simulations were conducted for several cases related to the processes of two tree species: Robinia pseudoacacia and Salix spp. The model was then applied in order to elucidate the forestation mechanism of the bar, which indicated a possible reason for the effect of decreasing the supply of coarse sediment. The impact of the tree and herbaceous plants by different hydrological processes is also discussed. Copyright © 2014 John Wiley & Sons, Ltd.
- Investigating Environmental Flows for Riparian Vegetation Recruitment
Using System Dynamics Modelling
- Authors: R. R. Morrison; M. C. Stone
Pages: 485 - 496
Abstract: System dynamics modelling is an underutilized tool that can provide flexible and system‐response analyses of environmental flows. Because system dynamics models are able to incorporate causal connections between social, economic and environmental aspects of a system, they are well suited to study water management problems. In addition, system dynamics models are excellent tools for incorporating expert and stakeholder feedback, which is an important component of any environmental flow study. Given the benefits of using a system dynamics modelling approach, our objective was to develop and demonstrate a stochastic system dynamics modelling framework to evaluate environmental flow alternatives. Specifically, our research examined the influence of flow alternatives on cottonwood recruitment and reservoir storage within the Rio Chama basin, New Mexico, USA. We used the ‘recruitment box model’ to investigate the impact of three alternatives on cottonwood recruitment within the project reach. The recruitment box model attributes seedling survival to floodplain elevation, annual timing of peak flows and river stage declines that match seedling root growth. We also demonstrate how flow alternatives can be evaluated using comparative metrics, which allow water resource managers to more easily evaluate alternatives before incorporating environmental flows into existing operations. Copyright © 2014 John Wiley & Sons, Ltd.
- A New Method to Assess the Flow Regime Alterations in Riverine Ecosystems
- Authors: X. A. Yin; Z. F. Yang, G. E. Petts
Pages: 497 - 504
Abstract: Assessing alterations of a river's flow regime provides the basis for river protection and restoration planning. The range of variation approach (RVA) is a commonly used method to evaluate alterations in a river's flow regime. However, RVA underestimates the degree of flow regime alteration potentially, because it only considers the difference in frequency between the pre‐impact and post‐impact hydrologic indicator values within certain target ranges and does not consider alteration of the order of hydrologic year types (HYTs; i.e. wet, average and dry years). The HYT order is an important holistic feature of the flow regime. The human‐induced change of HYTs, such as from a dry year to a wet year or from an average year to a dry year, can be a major cause of ecosystem alteration. For some species, the order of the HYTs was more important than single‐year events (such as the flood magnitude during a given year). To address this problem with the RVA, we proposed a modification of this method that accounts for alteration of the order of HYTs. We developed a metric for assessing the alteration of the HYT order based on Euclidean distance and then combined this metric with the RVA. We applied the revised method to a case study of the Sha River in northern China to test its effectiveness. The results demonstrated that the new method solved RVA's problem of potentially underestimating the degree of flow regime alteration and enabled a more comprehensive analysis of the alteration of the flow regime. Copyright © 2014 John Wiley & Sons, Ltd.
- A General Approach to Predicting Ecological Responses to Environmental
Flows: Making Best Use of the Literature, Expert Knowledge, and Monitoring
- Authors: J. A. Webb; S. C. Little, K. A. Miller, M. J. Stewardson, I. D. Rutherfurd, A. K. Sharpe, L. Patulny, N. L. Poff
Pages: 505 - 514
Abstract: Around the world, governments are making huge investments in environmental flows. However, much of the rationale for these releases is based on expert opinion and is thus open to challenge. Empirical studies that relate ecological responses to flow restoration are mostly case studies of limited generality. Radically, different approaches are required to inform the development of general models that will allow us to predict the effects of environmental flows. Here, we describe the modelling framework being used in a major study of environmental flows in the Australian state of Victoria. The framework attempts to make best use of all the information available from the literature, experts, and monitoring data, to inform the development of general quantitative response models. It uses systematic review of the literature to develop evidence‐based conceptual models, formal expert elicitation to provide an initial quantification of model links, and data derived from purpose‐designed monitoring programs over large spatial scales. These elements come together in a Bayesian hierarchical model that quantifies the relationship between flow variation and ecological response and hence can be used to predict ecological responses to flow restoration. We illustrate the framework using the example of terrestrial vegetation encroachment into regulated river channels. Our modelling framework aims to develop general flow‐response models and can immediately be used to demonstrate the ecological return on investment from environmental flow programs. However, the framework also has the potential to be incorporated into planning and decision‐making processes, helping to drive a transformation in evidence‐based practice for environmental flow management. © 2014 The
Authors . River Research and Applications published by John Wiley & Sons, Ltd.