bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biotic and abiotic gradients in a regulated high elevation Rocky mountain river
Authors: Voelz Neal J. , Ward J. V. 
Published: February 2007

AbstractSamples were collected year‐round over a one‐year period at sites 250m, 500m, 1000m, 2300m, 5200m, and 11000m downstream from a hypolimnetic‐release reservoir on the Blue River, Colorado, to examine biotic and abiotic gradients induced by river regulation. The impoundment had only minimal effects on river chemistry and chemical variables failed to exhibit discernible downstream patterns. The temperature regime was markedly altered by regulation and exhibited a distinct downstream recovery gradient. The progressive downstream increase in zoobenthos species diversity is attributed, in part, to the thermal recovery. The average size of mineral substratum particles was greater at sites nearest the dam, although cobble and pebble predominated at all sites. A downstream decrease in bed stability was accompanied by decreased water clarity and increases in scour and ice action. These factors may have accounted for the higher standing crops of periphyton near the dam and a shift from filamentous chlorophytes to a predominance of diatoms with increasing distance downstream. The amount of leaf detritus in the substratum increased downstream. The abundance of shredders, zoobenthic species that feed on leaf detritus, tracked the downstream increase in coarse sedimentary detritus. Spatial patterns of organic seston within the study reach, influenced partly by sloughing of periphyton, are thought to account for the downstream species replacement patterns exhibited within the filter‐feeder guild.
Serial discontinuities in a Rocky mountain river. II. Distribution and abundance of trichoptera
Authors: Hauer F. Richard , Stanford Jack A. , Ward James V. 
Published: February 2007

AbstractRiver regulation in the headwaters and middle reaches of the Gunnison River, Colorado, significantly altered distributions and abundances of Trichoptera fauna. Twenty‐five species were collected from mainstream samples, with the greatest species richness occurring at an unregulated, rhithron segment above the central reach dams. At sites immediately below the three hypolimnial‐release dams and a reregulation dam, species richness was reduced 35–90 per cent and abundance > 95 per cent. Net‐spinning caddisflies were the dominant trichopterans at unregulated sites; Arctopsyche grandis in the upper reaches (218 organisms, 586 mg dry mass m−2) and Hydropsyche cockerelli, H. occidentalis and Cheumatopsyche pettiti in the lower river (9041 total organisms, 6621 mg m−2), downstream from the last dam. The observed distributional pattern of low trichopteran densities in dam tailwaters and high hydropsychid densities at sites 60–80 km below the central reach dams is a classic expression of continuum resets and adjustments in response to stream regulation as predicted by the Serial Discontinuity Concept.
Exploitation rate, survival and movements of brown trout (Salmo trutta L.) stocked at takeable size in the regulated rivers Lågen and Otta, southern Norway
Authors: Skurdal J. , Hegge O. , Hesthagen T. 
Published: February 2007

AbstractTakeable size (age 4+, length 27–67cm), hatchery reared brown trout (Salmo trutta L.) were released into the rivers Lågen and Otta, the Glomma River System, southern Norway, in May‐July 1981 and 1983–87. The brown trout released in May gave significantly lower recapture rates compared to those released in June/July, i.e. 22.8 per cent compared to 41.6–58.0 per cent, respectively. Mean exploitation rate and survival rates ranged from 0.23 to 0.58 and 0.2 to 0.4, respectively, Within 15 days after release 50 per cent were recaptured, and 90 per cent were caught within 67 days. The frequency of recapture increased significantly with fish length in the length interval 30–45 cm, but decreased for bigger fish. The stocked brown trout were stationary and 95 per cent of the recaptures were caught less than 1 km from the site of release. Frequency of recapture ranged from 19.2 to 54.7 per cent in 6 experiments with takeable sized brown trout in different tributaries of the Glomma River System, and the variations are probably mainly due to differences in fishing pressure.
Water quality management in the Ruhr area
Authors: Imhoff Klaus R. 
Published: February 2007

AbstractThe Ruhr River is the major source of water supply for the North Rhine‐Westphalian industrial district. To ensure drinking water supply from the river a system of reservoirs has been constructed for low flow augmentation. Five additional river impoundments have been built for the abatement of nonpoint pollution.The Ruhr River Association was established in 1913. Its first task was the reduction of coarse pollution by mechanical treatment plants. Activated sludge plants were introduced as early as 1926. Developments continued and presently tertiary treatment is performed by polishing lagoons on one‐third of the Ruhrverband plants and a programme of storage and subsequent biological treatment of stormwater is underway. One important future task is nutrient removal from municipal wastewater by chemical precipitation and biological processes. Phosphorous concentrations in river water have to be diminished to fight eutrophication while nitrogen must be reduced because of drinking water considerations. Heavy metals have to be further controlled and organically attached halogens have to be diminished.
Observations on feeding relationships between fish predators and fish assemblages in a Mediterranean stream
Authors: de Sostoa A. , Lobon‐Cervia J. 
Published: February 2007

AbstractThe diet of native and introduced fish predators has been examined in two contrasting localities of a very fluctuating, Mediterranean stream, in relation to fish (prey) assemblage structure. The general patterns of all the species studied (Lutra lutra, Natrix maura, Salmo trutta, S. gairdneri, Esox lucius, and Leuciscus cephalus) seem to be the result of a generalist‐opportunist behaviour as their diets reflect the relative abundance of prey (fish) in the environment. The trophic levels are not well defined because of the opportunistic feeding of the predators and are also subjected to environmental changes. Non‐competitive dynamics is suggested to operate throughout the trophic web.
Effect of stream regulation on population parameters of atlantic salmon [Salmo salar L.] in the river Lærdalselva, western Norway
Authors: Brooks R. J. , Nielsen P. S. , Saltveit S. J. 
Published: February 2007

AbstractThe river Lærdalselva, West Norway, was regulated in the autumn of 1974. Regulation led to an increase in winter flow and a decrease in summer flow in a section where there was natural production of salmon. A slight decrease in summer temperature was also recorded in the uppermost part of this section. No data existed on juvenile Atlantic salmon before regulation and the regulation effect on juvenile fish population parameters is therefore based on samples taken from adult salmon in the period 1969 to 1984.No differences in growth, smolt age, and smolt size which could be related to the regulation of the river were found. The smallest mean sizes of yearlings (0+) were found in 1964 and 1967. After regulation the mean size was never lower than before. Mean smolt age was between 3–1 and 3–9 years, but after regulation never exceeded that found before. River growth was slow, three year old smolts growing faster than four year old smolts. However, there were no differences in river growth before and after regulation.
The impact of channelization on the hydrology of the upper river main, county antrim, northern Ireland—a long term case study
Authors: Essery Charles I. , Wilcock David N. 
Published: February 2007

AbstractThe impact of an arterial drainage scheme on the water balance of a 200 km2 catchment in Northern Ireland is quantified. Monitored changes in groundwater storage act as an independent check on conclusions about storage change derived from measurements of surface hydrology. Three subcatchments of the study area and one other independent experimental catchment constitute controls against which the impact of arterial drainage can be assessed. Fiver years' predrainage data and three years' post‐drainage data are examined.Stream flow from the floodplain area of the catchment has increased, especially low flows. Catchment water‐tables, however, as monitored in floodplain transects and disused farm wells have not been drawn down. Any immediate drainage benefits deriving directly from arterial drainage are difficult to detect. Groundwater evidence indicates that the likely source of the excess discharge is an underlying gravel aquifer that has been punctured by the deeper arterial channel.
Restoration and enhancement of engineered river channels: Some european experiences
Authors: Brookes Andrew 
Published: February 2007

AbstractAs government and organizations responsible for river mangement throughout the World become increasingly aware of the need to reconcile engineering objectives with nature conservation, alternative strategies for river management such as channel restoration are likely to continue to be developed and applied to particular areas.Based on the experiences of 15 restoration projects in Denmark and Britain the criteria which determine the success of such projects are outlined. The essential precursor to a successful restoration project is a thorough feasibility and planning study. The type of restoration work included in a project is constrained by a variety of factors, including the physcial environment and the project objectives. The detailed design needs to be tailored to the individual river reaches under consideration. Project planning should consider the timing and supeervision of construction and make recommendations on the nature of maintenance. A management plan is desirable and post‐project appraisal is essetnial to evaluate the long‐term hydraulic and environmental performances. These criteria have been applied to two recent projects carried out on the River Lambourn in Berkshire, England, and on the Elbaek in central Jutland, Denmark.
Engineering operations and invertebrates: Linking hydrology with ecology
Authors: Smith Colin D. , Harper David M. , Barham Peter J. 
Published: February 2007

AbstractThis paper describes a study of a river regulated by past engineering schemes carried out for land drainage purposes: the River Welland in the East Midlands of England. Benthic invertebrate family richness and total biomass was measured in riffles, pools, and runs separately and then related to the frequency of these physical parameters. Changes which have occurred as a consequence of (a) loss of channel length through meander cut‐offs and (b) alteration of substrate characteristics through dredging and lowering of the river bed, were quantified. Riffles comprised 20‐30 per cent of the channel in reaches not seriously altered by engineering; elsewhere dredging has reduced or eliminated riffles and pools, leaving uniform sandy runs as the dominant channel feature. Riffles, pools, and runs all contribute to overall ecological value but the riffle and pool biotopes supported higher macroinvertebrate biomass and family richness. We show that proposals for river management that address the ecological needs of invertebrate communities can thus be expressed as numerical recommendations for maintaining or enhancing the key physical features of a river. In consequence, conservation recommendations can be simplified and considered in the same form as the engineering requirements of land drainage.
The effects of impoundment on the physicochemistry of two contrasting southern african river systems
Authors: O'Keeffe J. H. , Palmer R. W. , Byren B. A. , Davies B. R. 
Published: February 2007

AbstractThe downstream effects of six impoundments on their respective physicochemical conditions over two years are compared for two contrasting for two contrasting rivers. The impoundments studied included two on a cool, clear, clean, acid, and short system with a steep gradient (Palmiet River), and four on a warm, turbid, polluted, alkaline, and relatively long system (Buffalo River). Where possible, results are also compared against predictions of the Serial Discontinuity Concept (SDC) of Ward and Stanford (1983), and the ‘recovery’ (discontinuity) distances are estimated for a number of variables.Major effects centred on changes in median spot temperatures and annual temperature ranges, particularly for dams regulating the upper reaches of both rivers. These upper river impoundments behaved similarly despite different release patterns; and caused only weak chemical effects, most of which recovered rapidly (within 3 km). Middle reach impoundments also behaved similarly despite different release characteristics, but they caused more pronounced changes and recovery distances were longer (up to 30 km).Observed exceptions to the predictions of the SDC included alterations to nutrient regimes of receiving reaches downstream of all dams, annual temperature range was affected downstream of headwater dams on both rivers, and all impoundments on both systems depressed flow fluctuations. Although the specific predictions of the SDC model are not generally borne out, it is regarded as a useful tool for testing the effects of impoundment on rivers, and the concept of ‘recovery distance’ forms a useful practical framework for management of releases.
Comparison of discharge methods and habitat optimization for recommending instream flows to protect fish habitat
Authors: Orth Donald J. , Leonard Paul M. 
Published: February 2007

AbstractReliable methods are urgently needed for recommending minimum instream flows to protect aquatic life. For basinwide planning purposes, simple methods, which require little or nor field investigations, are required. While these methods tend to be conservative, the degree to which they protect habitat for fish is seldom determined. We applied physical microhabitat models (PHABSIM) for nine target fish species in four streams in the upper James River basin, Virginia, U.S.A., to (1) identify optimum flows to protect the fish fauna, (2) investigate the relationship between optimum flow and average discharge, and (3) compare our findings with recommendations based on simple discharge methods. Micohabitat availability for riffle‐dependent species was most limited at low flows while microhabitat availability for pool‐dependent species was most limited at high flows. At each study site there was a rapid increase in riffle habitat as discharge increased above zero. Optimum flow was the flow that maximized habitat for the most habitat‐limited species or life stages. The recommended optimum flow increased with increased stream size but the slope was not constant; as stream size increased lower proportions of average discharge were required to maintain optimum habitat. Aquatic Base Flow recommendations (i.e. September median flow) provided varying, but reasonable degrees of habitat protection. The Montana method 10 per cent average discharge recommendation correctly identified degraded or poor habitat conditions and the 30 per cent recommendation corresponded to near optimum habitat in small streams but greater than optimum flow at the large stream site. Seven‐day, 1‐in‐10‐year low flows (7Q10) provide very limited amounts of physical habitat for riffle‐dwelling fishes. The results provide a basis for making preliminary flow recommendations in this region with readily available data. Future studies will be needed to test the assumptions that need to be made.
Management of the sai river and the Tatsumi Canal, Japan
Authors: Nakagawa Takeo , Miyae Shin‐Ichi 
Published: February 2007

AbstractThe Tatsumi canal, Japan, constructed by Hyoshiro Itaya in 1632, is of immeasurable cultural value. It has become evident that the canal will be destroyed by construction of a new dam planned by Ishikawa Prefecture. The Tasumi canal is described and an alternative measure that fulfills the purposes of the dam construction and preservation of the Tatsumi canal is proposed. The alternative measure consists of widening the channel of the Sai River for flood control, and modification of the existing Heraso checkdam so as to fulfil the requirements for hydroelectric power generation and water storage. The proposed alternative also allows the preservation of the natural environment around the dam site and maintenance of water‐quality in the Tatsumi canal.
The downstream impacts of the burgomillodo reservoir, Spain
Authors: Camargo Julio A. , de Jalon Diego Garcia 
Published: February 2007

AbstractThe Burgomillodo Dam, located in the middle Rio Duraton (north Spain, Duero Basin), has created a small eutrophic reservoir with a capacity of 15 × 106 m 3 and a maximum depth of 40m. Burgomillodo Reservoir is solely used for producing hydroelectric power. The regulated flow pattern of hypolimnial waters is characterized by higher daytime flows than those by night, with low flows at weekends all the year round. The environmental impact generated by this hydropower scheme on the river downstream was assessed by comparing physiochemical characteristics and aquatic communities of an upstream site (reference station) with those of three downstream stations, which were located 0–2, 2–5, and 7–6 km below the dam.Water temperature, pH and dissolved oxygen were significantly lower downstream from the reservoir. Hardness, alkalinity, suspended inorganic matter, and conductivity had reduced annual variability below the dam. Photosynthetic activity was directly involved in the recovery of dissolved oxygen and pH values.Species richness and abundance of macrophytes increased just below the dam. Macrobenthic and fish communities were composed of higher numbers of potamic species. Number of taxa, density, biomass, and diversity were higher at the reference site, recovering their values as the distance below the reservoir increased. Macrobenthic trophic structure was changed by an increase in predators and filter feeders and a decrease in shredders. Environmental impact values for the macrobenthic community living just below the dam were higher than those for the fish community.It is concluded that the main physiochemical factors involved in environmental impacts were dissolved oxygen deficit and short‐term flow fluctuations for the macrobenthic community, and oxygen deficit for the fish fauna. Benthic macroinvertebrates appear to be the best aquatic organisms for detecting changes and for reflecting the spatial recovery of environmental conditions.
Habitat utilization and preferences in juvenile atlantic salmon (salmo salar) in streams
Authors: Heggenes Jan 
Published: February 2007

AbstractYoung Atlantic salmon appear to occupy similar suitable stream habitats year round. The salmon is stationary, often associated with “home stones”. At low water temperatures in winter, the fish seek shelter in the substrate, which has to be coarse enough to provide interstices for the fish to hide in. In summer, salmon select habitats within tolerable ranges of habitat variables, rather than narrow optima. It is suggested that a genetic basis to habitat evaluation allows incorporation of the full range of behavioural responses. This is important as partially different habitats may be selected in diverse streams. Habitat availability influences both habitat use and habitat preferences. Suitable summer habitats have depths in the range 5–90 cm; mean water velocities 10–80 cm s−1, and gravel‐to‐boulder substratum. Fish size affects habitat use, as young of the year are found in the more shallow habitats closer to the stream banks, whereas the older parr use a wider range of habitats. In the absence of brown trout, the Atlantic salmon parr, and especially young of the year, use habitats otherwise inhabited by brown trout. Water velocities are in many cases the principal physical habitat variable determining the distribution of Atlantic salmon in streams, but other variables are also important. Depth is more important in small streams than in large streams.
Response of montane meadow vegetation after two years of streamflow augmentation
Authors: Henszey Robert J. , Skinner Quentin D. , Wesche Thomas A. 
Published: February 2007

AbstractChanges in montane meadow vegetation were examined in a previously ephemeral drainage that received flow augmentation as a mitigation measure for a transbasin diversion in southeastern Wyoming. After two years of elevated surface and groundwater levels, the herbaceous vegetation shifted toward more water‐tolerant species. Dry meadows became like moist meadows, moist meadows became more like moist‐wet meadows, and moist‐wet meadows became more like wet meadows. Sedge (Carex spp.) biomass increased from 337 to 456 g m−2 in the wet meadows, while tufted hairgrass (Deschampsia cespitosa) biomass decreased from 18 to 3 g m−2 in the moist‐wet meadows. Slimstem reedgrass (Calamagrostis neglecta) remained unchanged in the meadows with shallow standing water, but increased from 17 to 88 stems m−2 in the dry meadows with an elevated water table. Bare ground also increased as much as 31 per cent in the meadows without a defined drainage channel.
The effects on fish spawning and management implications of impoundment water releases in an intermittent South African river
Authors: Cambray J. A. 
Published: February 2007

AbstractThe potamodromous smallscale redfin minnow (Pseudobarbus asper) spawned in the riffle areas of the regulated Groot River, the major tributary of the Gamtoos River system, during controlled releases of water from Beervlei Dam. Water had been released at irregular intervals from this flood control dam solely for irrigating agricultural lands. Flushing flows removed accumulated salts from riverine pools and were followed by reduced flows which initiated spawning of the minnow species. Developing embryos of P. asper were found in the riffle zone of the main river channel during the water releases. Ripe‐running males were located under the boulders in the riffles. Several developing embryos of Labeo umbratus were found with the P. asper eggs. Very little is known about the effects of man‐made alterations to the river flow regime on the reproductive activity of fishes in the majority of South African river systems. The agriculturally based flooding regime at Beervlei may have increased the recruitment of the redfin minnow species. Water management must give cognizance to the biological and environmental requirements within the regulated river systems. Water release strategies from Beervlei Dam should include instream flow decisions based on the requirements of the aquatic environment as well as for agriculture.
The flood pulse advantage and the restoration of river‐floodplain systems
Authors: Bayley Peter B. 
Published: February 2007

AbstractThe ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river‐floodplain system, this restoration would provide a large, self‐sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.