bluuebunny/crossref_metadata_2025_split huggingface dataset:
The conservation value of water supply reservoirs
Authors: Moore David , Driver Alastair 
Published: February 2007

AbstractThere are over 500 water supply reservoirs in England and Wales, a total water surface of 20000 hectares, much of which has been flooded this century. Waterfowl, amphibious and aquatic wildlife have all benefited from this change, especially important after so much wetland has been drained and ploughed to increase agricultural production. Modern reservoirs include landscape and conservation in their planning, construction and operation, often leading to their notification as Sites of Special Scientific Interest soon after their construction. Examples in the Anglian Water and Thames Water regions are discussed to demonstrate their value to wildlife as well as fulfilling their prime function for water supply. Pitsford Water (Northamptonshire), Rutland Water (Leicestershire), Staines Reservoirs (Surrey), and Walthamstow Reservoirs (Greater London) show varying levels of conservation planning. Protection from recreational activity is shown to be an essential part of management at these sites.
Stream channel and habitat changes due to flow augmentation
Authors: Wolff Steven W. , Wesche Thomas A. , Hubert Wayne A. 
Published: February 2007

AbstractA previously ephemeral stream is being used to convey water and create fish habitat as part of mitigation for impacts of a transbasin water diversion project. This stream, the South Fork of Middle Crow Creek, is located in the Medicine Bow National Forest, Wyoming. After two years of increased flow to the 8.8 km study reach, the amount of stream channel had increased 32 per cent and the total area of beaver ponds had more than doubled. Brook trout (Salvelinus fontinalis) stocked into the beaver ponds are surviving and growing. Factors limiting fishery development in the augmented stream include interrupted flow, discontinuous channels, and summer water temperatures exceeding 25°C. Analysis using the Physical Habitat Simulation System indicated that a flow of 0.07m3s−1 would maximize the amount of weighted usable area for brook trout under the channel conditions present in 1987.
Trichoptera and ephemeroptera as indicators of environmental changes of the Rhone river at lyons over the last twenty‐five years
Authors: Usseglio‐Polatera Philippe , Bournaud Michel 
Published: February 2007

AbstractSystematic light trapping was carried out in Lyon on the banks of the Rhǒne river from 1958 to 1982, mainly in the months of June and July. The changes in the type and abundance of the adult Trichoptera and Ephemeroptera species captured over the last 25 years were studied in relation to the perturbations sustained by the river‐and thus by the larval instars.A Correspondence Analysis carried out on the monthly samples defined a first factorial axis which could represent a ‘biological time’ scale characterized by phases of rapid (1959‐1974) or slower (1974‐1982) change of the faunal communities.Five ‘successive’ faunal groups were defined according to the length of historical presence of each of the 88 species along this axis. The most stenoecic species (faunal groups 1, 2 and then 3) seem to disappear and gradually only a small number of species whose ecological requirements are less demanding (faunal groups 4 and 5) subsist.This faunal impoverishment is a consequence of the increasing uniformity of the biotope caused by continuous environmental changes mainly in flow regulation. This has led to reduction in diversity of the substratum and possible food sources. Regular flush‐outs of upstream reservoirs release sediments which clog interstitial spaces over long periods and this effect has been aggravated since 1966 by the bringing into service of a dam situated just downstream from the station.It seems that a new but delicate equilibrium has been reached since 1974; this situation probably corresponds to a less stenoecic biotic community.
Factors affecting the distribution and abundance of aquatic plants in a navigable Lowland river; the River Nene, England
Authors: Brierley S. J. , Harper D. M. , Barham P. J. 
Published: February 2007

AbstractInvestigations were conducted into the causes of a decline in the abundance of rooted aquatic plants in the River Nene. These were formerly troublesome to navigation and obstructed summer storm flows and were regularly cut by Anglian Water until 1976. After 1977 plant growth caused only localized problems so cutting ceased. An investigation into the causes of the plant decline was initiated in order to provide predictions for management decisions about the future use of machinery and personnel. It was concluded that there was a natural loss of plants by scouring in the abnormally high flows of 1976/7 winter. The regular pattern of maintenance dredging, which had been implemented following water industry reorganization in 1974, was shown to suppress abundance for at least five years after dredging. These two sequential events had lowered abundance over the navigable Nene to levels which no longer warrant weedcutting.
The effect of an irrigation and hydroelectric reservoir on its downstream communities
Authors: Casado C. , de Jalon D. Garcia , Delolmo C. M. , Barcelo E. , Menes F. 
Published: February 2007

AbstractThe Cernadilla reservoir, located on the River Tera (northwest Spain, Duero Basin) is an oligotrophic reservoir with a capacity of more than 250 × 106m3 and a depth of 70 m. The regulated flow pattern is characterized by higher summer flows, higher day flows than night ones, and lower weekend flows. The effects of this artificial flow regime on the stream ecosystem were evaluated by comparing the aquatic communities of an upstream station with those of three downstream stations, located at 1, 8, and 24 km from the dam. Physiocochemical characteristics of the water, fish and macrobenthic communities, and macrophytes were studied at each station.Summer water temperatures were significantly lower downstream of the reservoir. Macrophyte biomass, macrobenthic diversity, and richness were reduced below the dam. The trophic structure was changed by an increase of shredders and grazers.Fishery total biomass greatly fluctuated seasonally, but was higher above the reservoir than below it. However, in spring the trout populations were higher upstream because large numbers of spawning cyprinids from the reservoir invaded upstream reaches of the River Tera and displayed resident trout populations.
A review of the effects of water transfers in the La Grande Hydroelectric Complex (Québec, Canada)
Authors: Roy Dominique , Messier Danielle 
Published: February 2007

AbstractConstruction of the La Grande Complex in Eastern Canada called for complete or partial diversion of six rivers, the mean annual discharge of which varied from 60 to 1600 m3 s−1, and the transfer of water from two adjoining watersheds (1586m3 s−1) into La Grande Rivière. Three of these rivers with reduced flow, Eastmain (from 700 to 95m3 s−1), Opinaca (from 260 to 35m3 s−1), and Caniapiscau (from 1708 to 960m3 s−1) and the waterways with increased flows, Boyd‐Sakami (from 1 to 811m3 s−1) and La Grande Rivière (from 1760 to 3400m3 s−1) were intensively monitored from 1978 to 1988, while the others were surveyed sporadically. Very few modifications were observed, compared to previous conditions, in banks stability, water quality, and aquatic fauna of the affected rivers: those which appeared can be explained by the water level fluctuations, the water quality of the tributaries of the residual drainage basin, and/or by the direct influence of the reservoirs. In James Bay, the areal extent of the Eastmain River and La Grand Rivière plumes varied with discharge in an exponential relation, mostly under ice cover; resources from the coastal environment had not yet undergone any major changes. Because of the very small population dwelling in the area, less than 3000 inhabitants, modifications in the hydrological regime of these rivers did cause relatively few impacts, the main being greater banks instability in specific locations, reduction of the thickness and ice cover on La Grande Rivière, enhancement of navigation constraints on Eastmain River, and higher mercury levels in fish related to operation of the reservoirs.
The increasing damming of the Paraná basin and its effects on the lower reaches
Authors: Bonetto A. A. , Wais J. R. , Castello H. P. 
Published: February 2007

AbstractThe development of large impoundments along the Paraná river, particularly on the Superior section, with fifteen large dams having a capacity over 25000 MW, has had important hydrological and ecological impacts on the lower reaches. The important retention of the suspended solids by the dams has caused a significant reduction of P concentrations. With river impoundment and water eutrophication, cyanophiceae currently dominate during spring and summer, with brief but dense blooms of Anabaena spiriodes and Microcystis aeruginosa. Many fishes of the Superior Paraná have been dispersed downstream as the Itaipú reservoir covered the Guayra falls, the natural barrier for these fishes.The most important effects of Superior Paraná dams are related to the changed hydrological regime in the alluvial Middle and Lower reaches. This floodplain plays an important role in the bioproductivity of the river. Fisheries production depends to a high degree on the relationship of the river and its alluvial valley, where the alevines and small fishes of migratory species develop after spawning. During falling river levels the waters carry large quantities of organic matter, floating vegetation, important amounts of plankton and fishes from the alluvial plain to the river. Before the dams, the river defined two subsystems which were joined for about six months during the flood season and effectively isolated during low water periods.Since the commencement of river impoundment and flow regulation, the river ecology has begun a sequence of changes especially within the alluvial reaches.
Chinook salmon spawning surveys in deep waters of a large, regulated river
Authors: Swan George A. 
Published: February 2007

AbstractIn 1986 research divers surveyed and mapped deep‐water spawning redds of fall chinook salmon (Oncorhynchus tshawytscha) in selected sites within an impounded segment of the main‐stem Columbia River, Washington State, U.S.A. In velocities over 3m s−1 and depths up to 11 m, two divers riding a manoeuvrable sled made cross‐current transects communicating observations of substrate materials and deep‐water spawning sites. Surface personnel tracked the position of the sled with a laser locating system that logged the information into data storage. Subsequently, the computerized data were translated into overlaying maps depicting location of redds, substrate materials, and depth contours.Deep‐water spawning (>3m) occurred at most survey sites in velocities between 0.6 and 0.8m s−1. The average depth of spawning was 6.5 m, and the maximum was 9.1 m‐deeper than the depth redds can normally be detected by aerial observation (3–4 m). Deep‐water spawning ranged from none to substantial in areas of near identical physical characteristics. A method for estimating abundance and density of deep‐water redds, based upon the data collected with this mapping technique, is presented. This study combined with current limited information concerning deep‐water spawning suggests that up to 80 per cent of the escapement of fall chinook salmon in this reach may spawn in deep water.
Time scales for the recovery potential of river communities after restoration: Lessons to be learned from smaller streams
Authors: Fuchs Ulrike , Statzner Bernhard 
Published: February 2007

AbstractGerman politicians have promised that the River Rhine will be sufficiently restored within twelve years to permit salmon to live there again. Obviously the large rivers in Central Europe are more isolated from each other than smaller streams, and communities donating potential colonizers (if they exist at all) are further apart for possibly restored large rivers than for smaller streams. Thus, recovery can be expected to be faster in small streams than in big rivers after restoration (or reduction of detrimental human influence). Therefore, two restoration projects in German lowland streams, which differ in their degree of isolation, can serve as an indicator to the time periods which could at least be expected for the recovery of Central European rivers.Under optimal conditions (almost completely intact communities upstream and downstream of a 400 m restored reach) in North Germany, sufficient recovery of benthic macroinvertebrate fauna could be achieved in relatively short periods. However, in a rather isolated stream reach in the Upper Rhine valley (closest intact lotic ecosystems of a comparable type were found 20‐25 km away) a sufficient recovery of benthic macroinvertebrate fauna was not achieved within five years after restoration, although there was high diversity of physical habitats and the water quality was acceptable (except for two oil accidents in the fourth and the fifth year).Hence, we conclude that recovery of a large Central European river ecosystem like the Rhine, which has lost a large number of its former species and is more isolated than small streams, will require more than twelve years to reach a state significantly different from the present one.
The riparian woody plant community of regulated rivers in eastern England
Authors: Mason C. F. , Macdonald S. M. 
Published: February 2007

AbstractThe riparian woody vegetation (trees and shrubs) is described from a survey of fifty 1 km stretches of rivers in East Anglia, England, between 1985 and 1987. Tree loss along three rivers was estimated from 1879 maps and aerial photographs taken in 1960 and 1970. A total of 48 species of trees and shrubs were recorded, with Alnus glutinosa, Salix alba, and S. fragilis dominating the overall community. Overall tree density ranged from 0 to 185 km−1, average 73 km−1. The majority of stretches had less than 25 mature trees, with less than 10 individuals of any one species. Sites were classified, based on the frequency of occurrence of species, into four groups using TWINSPAN. Marked decreases in densities of riparian trees were apparent over the period 1879–1970, averaging 8 per cent per annum on the river with the greatest initial starting densities. Tree densities, counted from the aerial photographs of 1970, ranged from 25–35 km−1. The results from East Anglia are compared with a similar study from a less intensively managed region in western Britain.
Element transport in regulated and non‐regulated rivers in northern Sweden
Authors: Brydsten Lars , Jansson Mats , Andersson Tord , Nilsson Åke 
Published: February 2007

AbstractThe transport of HCO3−, SO42−, Cl−, Ca2+, Mg2+, Na+, K+, Tot‐P, MRP, Tot‐N, NO3‐N, NO2‐N, NH4‐N, Fe, Mn, silica, particulate material, and organic material (total and dissolved) were compared in three rivers regulated for the expoitation of hydroelectric power and in three unregulated rivers in northern Sweden. This evaluation was done by statistical analysis of data derived from monthly sampling near the outlets of the rivers during the period 1972–1986. Significant differences due to regulation were found for particulate matter, total‐P, Fe, and silica. Regulation decreased the transport by 10–50 per cent depending on the parameter and the river. The explanations for this effect are sedimentation of particles in impoundments and decreased erosion of the river bed due to the elimination of runoff during the snow melt period. The reduced transport of phosphorus may affect the productivity of the coastal zone of Bothnian Bay into which the rivers discharge.
Fisheries ecololgy and management of the Jaraqui (Semaprochilodus Taeniurus, S. Insignis) in central Amazonia
Authors: de Brito Ribeiro Mauro Cesar Lambert , Junior Miguel Petrere 
Published: February 2007

AbstractThe decline of heavily exploited stocks of large, high quality, food fishes in central Amazonia has led to increasing fishing pressure on smaller taxa, especially the jaraqui (Semiprochilodus spp.). The Prochilodontids, now the most important species to the fisheries, are seined by commercial fishermen during three distinct peridos. At the beginning of the annual floods, schools of mature jaraquis in poor‐water tributaries migrate downstream to spawn in the nutrient rich white‐water rivers. During these rapid spawning runs, fishing effort is concentrated in the lowermost reaches of the tributaries. After spawning, they return in small groups to feed intensively in the flooded forest of the same tributaries from which they had migrated. This period, of approximately three months, may be considered as a natural closed season to the fisheries. The dispersal migration is most complex and requires distinct fishing strategies. In the middle of the floods large schools of fat jaraqui descend from the tributaries to the white‐water rivers again. From there, they move upstream to different poor‐water tributaries. As downstream movements are more diffcult to observe, fishermen remain at fixed fishing grounds. This contrasts with the dynamic strategies of the subsequent upstream fishing period which contributes 60 per cent of the annual catches.Fluctuations in catch are shown to reflect year to year variations in abundance, which are linked to the hydrological cycle. Considering that fishing over the stocks of jaraqui has already more than compensated for the deficit in catch of larger species, a combination of increased effort and environmental problems could lead, in a short period to a depletion of one of the most profitable fisheries of central Amazonia. Regulation of the fisheries could benefit from a more reasonable distribution of effort among other migratory illiophagous species which remain unexploited, if the goal of sustainable yield and conservation of these stocks is to be achieved. Reserved waters in large strategic units of at least 300 km along white‐water rivers (which is equivalent to the maximum upstream displacement of jaraqui during their dispersal migrations) could also be useful to compensate for the loss of floodplain areas due to deforestaion, river regulation, use of pesticides, and mining. River impoundments in tributaries in central Amazonia may have little effect on jaraqui stocks, as spwning movements are unlikely to be directly interrupted by dams. However, alterations of the hydrological regime may also benefit from simulation of the flood cycle to mitigate potential negative impacts.
Classification of the macroinvertebrate fauna of two river systems in Southwestern Australia in relation to physical and chemical parameters
Authors: Storey A. W. , Bunn S. E. , Davies P. M. , Edward D. H. 
Published: February 2007

AbstractBenthic macroinvertebrates were quantitatively sampled from thirty sites along two river systems in southwestern Australia, and patterns in community structure related to physical and chemical parameters. Classification and ordination showed a major separation between upland and lowland sites, irrespective of river system. The change in benthic community structure reflected the rapid transition in geomorphology, stream hydraulics, and water chemistry as upland forested streams exit the Darling Escarpment to give rise to open rivers, disturbed by agriculture and urban development.One upland site was clearly influenced by a storage reservoir immediately upstream and consistently grouped with lowland sites; evidence of recovery was apparent at sites downstream. The remaining upland sites were separated on the basis of catchment; this was most likely related to stream flow permanence than any inherent catchment difference. A seasonal pattern was also detected for upland sites. Samples taken in summer or autumn were distinct from those taken in winter or spring.In constrast, lowland sites could not be separated into distinct groups on the basis of season or drainage basin. The presence of cosmopolitan and tolerant species with a high likelihood of dispersal, together with the homogeneous nature of the sites, may account for the high degree of similarity among benthic communities of sites along the lowland rivers.Much of the spatial and temporal variation in benthic community structure was explained by physical characteristics of the sites. Prediction of community type using chemical data alone was poor, however, this success could be improved by combining physical and chemical data, particularly for upland sites. The poor predictive success using chemical data was likely the result of the abrupt changes in the physical nature of the streams, and the absence of large spatial differences in water quality.The successful predictive relatioship betweenm benthic community structure and physical data will enable water management authorities to detect subsequent changes in water quality in these two river systems. The predictive power of the model could be assessed in adjacent river systems for which the patterns in benthic community structure are as yet unknown.
Variability of results from the use of PHABSIM in estimating habitat area
Authors: Gan Kein , McMahon Thomas 
Published: February 2007

AbstractThe estimation of the area of a stream reach suitable as habitat for an aquatic species by the Instream Flow Incremental Methodology is described. An important component of the methodology is PHABSIM, which is a collection of computer programs whereby useable stream area is computed as a function of discharge. This comprises a variety of options for both hydraulic and habitat simulation. A single data set is used to calculate the useable area at one discharge for three life stages of brown trout, using various options in habitat simulation. The results are shown to vary greatly according to the particular combination of options selected, so unless calculations are founded on biologically realistic assumptions the potential within PHABSIM for the „fudging”︁ of results is considerable.
Effects of sediment and flow regime on the aquatic insects of a high mountain stream
Authors: Debrey Larry D. , Lockwood Jeffrey A. 
Published: February 2007

AbstractIn 1984, a broad size range of sediment (boulder to sand) was introduced into a high elevation Rocky Mountain stream in southeastern Wyoming, U.S.A. In the spring of 1986, this stream was exposed to a high discharge of 7.5 m3 s−1. From 1985 to 1987 a study was conducted to assess the impact of sediment deposition and flow regime on the aquatic insect community in context of the substrate occurrences of the insect fauna. Using a modified Surber sampler, samples were collected from June through September each year at nine stations which were rated as unimpacted, slightly‐impacted, and impacted. The addition of the sediment had minimal effect on the abundance and diversity of aquatic insects. However, high water discharge severely reduced the abundance of aquatic insects and diversity was also negatively impacted. Recovery from these impacts was very rapid. The greatest insect abundance was found in samples taken in gravel and most taxa occurred predominantly on gravel or rubble substrates.