bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endangered fish species of the Danube river in Austria
Authors: Schiemer Fritz , Spindler Thomas 
Published: February 2007

AbstractThe ecological affinity of fish species to different habitat types in the course of their life cycles is investigated in the free‐flowing sections of the Austrian Danube. The results point to the great significance of the degree of hydrological integration between the river and its adjoining waters. In the breeding and fry stage, rheophilic species are bound to the river itself, but the preferred zones show great variations according to both fish age and species. A highly structured shoreline is important in providing a gradient of water current and a spectrum of food sources. Regulated embankments are characterized by an extremely reduced fauna with low population densities of eurytopic species. These results give evidence that the conservation of the characteristic species association is incompatible with the planned hydroelectric power dams in the remaining, free flowing zones of the Danube. The importance of the fish fauna as an indicator group for the condition of large river systems is discussed from the conservation point of view.
Relationships between actinomycete populations and organic matter degradation in Lake Mulwala, southeastern Australia
Authors: Boon P. I. 
Published: February 2007

AbstractThis communication examines the proposal that actinomycete populations, and thus the occurrence of taste and odour problems in potable water supplies, are related to the input of organic matter to reservoirs. The number of actinomycetes in Lake Mulwala, a man‐made lake in southeastern Australia, ranged from 2–80 ml−1 in the water column, and 2.7–12 × 104cm−3 in the sediments. Population densities in the water column and sediments were greatest in winter and summer, respectively. They were not highly correlated with protein or polysaccharide degradation. The weak relationship between actinomycete numbers and the rate of organic‐matter breakdown was probably due to metabolic inactivity of the bacteria, since actinomycetes in the sediments occurred mainly as spores rather than as vegetative cells. Limiting the input of organic matter, for instance by the removal of fringing vegetation, will have little effect on actinomycete populations in this reservoir.
Water mangement and ecological perspectives of the upper rhine's floodplains
Authors: Dister Emil , Gomer Dieter , Obrdlik Petr , Petermann Peter , Schneider Erika 
Published: February 2007

AbstractThe diverse Upper Rhine floodplains (with regard to geomorphology, hydrology, vegetation, and fauna) have undergone far‐reaching changews over the last 170 years, intensified from 1955 to 1977, especially as a result of water engineering measures.Far‐reaching and serious distrubances of the ecological balance (flood problems, lowering of the water table, etc.) and the drastic reduction of biotic communities, as well as the increasing demands of society, call for a newly oriented policy with regard to the future development of the Upper Rhine floodplains. This should be based on a critical review of the recent history of the landscape and a recognition of the ecological importance of these floodplains.
River engineering in national parks: The case of the river Wharfe, U.K.
Authors: Hey R. D. , Winterbottom A. N. 
Published: February 2007

AbstractRiver engineering works have recently been carried out on the upper River Wharfe (U.K.) in order to reduce the flood risk and resore land drainage beween Hubberholme and Kettlewell. As the river is located in a National Park, great care had to be exercised to limit the degree of interference and to ensure that an environmentally acceptable solution was adopted.Increased flood risk can be partially attributed to afforestation in the headwaters of the Wharfe. Improved drainage prior to planting has lead to an apparent increase in the mangitude and frequency of flooding and an increase in sediment yield.The works were to remedy both problems and were designed in consultation with a range of conservation and amenity organizations. First, a bed load trap was constructed on the Wharfe to curtail the sediment supply to the flood prone reach and prevent further aggradation. Second, limited dredging was carried out near tributary junctions to improve land drainage on the floodplain. Third, the dredged material was used to form the core of the raised banks.The engineering works were carred out between 1985‐87. Since completion in August 1987 the flood banks have been overtopped only twice which compares with the previous record of thirty‐two times per year. No significant erosion or deposition has occurred and the gravel trap is performing according to expectations; being half full after two and a half years of operation. Although stocks of mature trout were displaced by bed workings, there are now signs of a recovery.
Restoration of fish communities of the rhine river two years after a heavy pollution wave
Authors: Lelek Anton , Köhler Christian 
Published: February 2007

AbstractThe Rhine may provide a classical example of faunistic changes due to Man‐made stress. Formerly a salmonid river, it was transformed into a ship‐canal. Steadily increasing pollution culminated in the 1960s and 1970s. An improvement of water quality in the 1980s was followed by an increase in abundance of several species and faunal diversity. Originally 47 species inhabited the Rhine; at present 40 indigenous and 15 introduced species live in the river, seven have vanished or have not been observed so far. Recent setabacks, like the Sandoz Accident in 1986 failed to eliminate any taxon. Protection of the indigenous fauna is to be linked with conservation of remaining environmental diversity, ecotechnical improvements, and new strategies in fishery management, which do not merely support only economic species.
Changes in plankton communities in regulated reaches of the lower river rhine
Authors: de Ruyter van Steveninck E. D. , Admiraal W. , van Zanten B. 
Published: February 2007

AbstractThe Dutch section of the Lower Rhine is highly modified by regulating measures, such as the construction of weirs and the closure of estuarine river mouths, which seriously affect sedimentation of suspended material. During 1987 the fate of plankton communities in this part of the Rhine was investigated. Water samples were taken fortnightly at the German‐Dutch border and in the main branch of the Rhine, just before it debouches into the North Sea. Dry weights of suspended matter, bacterial numbers, phytoplankton biomass (as chlorophyll a) and zooplankton composition and biovolumes were determined, and, at two occasions, phytoplankton composition and biovolumes as well. Supended matter and bacteria disappeared during transport in the Rhine Delta. phytoplankton biomass (primarily diatoms) showed typical spring and summer peaks and also decreased in the investigated river reach. In contrast, zooplankton developed a higher biomass due to an increase in the numbers of rotifers, crustaceans, and molluscan larvae, whereas arcellas and ciliates decreased in numbers.It is concluded that the Rhine, after flowing more than 800 km, meets in its delta the proper conditions for a true plankton community to develop: settling and trophic interactions become of increasing importance in determining the structure of plankton communities.
Effects of fluctuating levels of lake superior on morphological adjustments in the neebing‐mcintyre floodway, thunder bay, Ontario Canada
Authors: Rasid Harun , Phillips Brian A. M. 
Published: February 2007

AbstractThe Neebing‐McIntyre Floodway, a relatively straight, trapezidal flood‐control channel, was constructed in 1983 to dispose of the combined flows of the Neebing and the McIntyre rivers into Lake Superior. Because of its location in a transitional fluvial/lacustrine environment, related processes had direct and indirect impacts on its morphological readjustments. During the post‐construction period (1983‐88) the combined peak flows of the Neebing and the McIntyre rivers never exceeded the two‐year design floods for the floodway, resulting in relatively low stream power and sediment transport rates. The average rate of sedimentation in the new channel (1100 m3 y−1) was thus much lower than the designers' estimated volume (11 800 m3 y−1). These low‐flow events coincided with high water levels in Lake Superior in 1985‐86, reinforcing the normal backwater effect in the floodway and further dampening its stream power. During this event the floodway behaved hydraulically almost like a reservoir, with fluctuating water levels and wind‐generated waves as the principal geomorphological agents of bank erosion. Estimates based on volumetric surveys indicate annual rates of bank erosion ranging from 0.03 to 0.16 m3 m−1 of bank length, with an average annual rate of 0.1 m3 m−1. The bank materials are composed of highly erodible sandy loam and loamy sand, which have a tendency to disperse and liquefy relatively easily. There are no significant spatial variations in erosion rates along a given bank but contrasts in the magnitude of erosion between the north and the south banks can be related to the relative exposure of a bank to average wind velocities, total duration of winds and the effective wind‐wave fetches.
Interactions between geomorphological processes, benthic and hyporheic communities: First results on a by‐passed canal of the french upper rhône river
Authors: Chatelliers M. Creuze Des , Reygrobellet J. L. 
Published: February 2007

AbstractOn the basis of data collected from several previous studies on the Miribel Canal, a by‐passed section of the Upper Rhône river near Lyon (France), an ecological methodology, based on geomorphology and dealing with both benthic and hyporheic layers of the river bed, has been set up and tested at the scale of the whole reach. The methodology allowed the description, by single spatial survey of, a “functional profile” of the canal incorporating both hydrological and faunistic fluxes. The ecological importance of riffles is emphasized and the results indicate that, even in this kind of disturbed channel, geomorphological processes (degradation/aggradation…) act as ecological constraints, especially in the hyporheic layers where they determine community structure by influencing groundwater circulation. The methodology proved to be a good tool over different scales for ecological studies of fluvial systems.
Ecological implications of the analysis of the redox system of organic matter in the streams of vizcaya (Northern Spain)
Authors: de Bikuña Begoña G. , Docampo Luis 
Published: February 2007

AbstractEleven physicochemical variables (pH, temperature, oxygen, percentage of oxygen saturation, orthophosphate, nitrite, nitrate, ammonium, orthosilicate, organic matter and organic matter in sediment) have been analysed in 175 sampling sites during four seasons in 1985. A principal component analysis has been applied after standardization of the density function of the variables, according to skewness and kurtosis. Four main groups of sites have been differentiated. These groups represent different degrees in the redox process of organic matter. (A) Very oxygenated sites with high pH values indicating that the mineralization process prevails. Organic matter appears in low concentrations and a reduced state. (B) Sites nutrient enrichment where elements with high oxidation number prevail (nitrite, nitrate, and orthophosphate). (C) Sites supporting high organic pollution. (D) Sites subjected to heavy urban and/or industrial dumping.
Effect of two temperature regimes from a deep and a surface water release on early development of salmonids
Authors: Grande Magne , Andersen Sigbjørn 
Published: February 2007

AbstractIn order to test the effect of regulated water temperature on the development of eggs and alevins of three salmonid species, deep and surface water from an oligotrophic lake was pumped into a hatchery. Atlantic salmon (Salmo salar) clearly needed the highest number of degree‐days to reach the different developmental stages while brown trout (Salmo trutta) needed just a little more than the brook trout (Salvelinus fontinalis). Eggs and alevins developed in the surface water, which was colder in winter, needed a lower number of degree‐days to reach the hatch and swim‐up stages. In spite of this there was a considerable difference in time for hatching and start of feeding of fish in the two temperature regimes. This might have consequences for the reproduction success and competition between species in regulated rivers.
Off‐river storages as sources and sinks for environmental contaminants
Authors: Higgins Roger J. 
Published: February 2007

AbstractOff‐river storages accept water from their adjacent stream, often when streamflow is high, and may return water to the stream when streamflow is low. In addition, off‐river storages usually have a water catchment of their own, independent of the main stream, which may contribute a significant proportion of inflow to the storage in total or on some occasions. Off‐river storages have many uses including water supply and flood mitigation, and can also be a significant resource in their own right.In the same manner that off‐river storages receive, hold, and subsequently discharge water flow, so contaminants contained in the water column may be received, held, and released. However, the timescale of contaminant retention and release may be quite different from that applying to water flows. Also physical, chemical and biological processes in the storage may alter the nature of the contaminants, such that released materials have different environmental implications from those input. This paper presents a discussion of the role of off‐river storages in contaminant movement and distribution in a river reach, and a framework for assessing the influence of these storages on the riverine environment. Case‐study data from the Fly River catchment in Papua New Guinea is then examined in this framework.
The use of non‐persistent herbicides, glyphosate, and 2,4‐D amine, to control riparian stands of Japanese knotweed (reynoutria japonica houtt.)
Authors: Beerlin D. J. 
Published: February 2007

AbstractThe non‐persistent herbicides glyphosate and 2,4‐D amine were applied to riparian stands of R. japonica on the banks of the River Cynon, South Wales at doses of 2154 g and 2790 g active ingredient (a.i.) ha−1 respectively. Glyphosate being tested with one or two applications per season, 2,4‐D amine with two only. Two weeks after spraying, the biomass and leaf area ratio of shoots in all treated plots was depressed but was significantly (P < 0–01) lower in the 2,4‐D amine plots. Ten weeks after treatment shoots had begun to recover but the biomass was still < 40 per cent of the control areas. Rapid (six weeks after treatment) recovery of Leaf Area Ratio was also observed. Second applications of glyphosate and 2,4‐D amine to the respective plots resulted in shoot death after four weeks. Management recommendations are made for the control of R. japonica on riverbanks based on the results presented.
Numerical simulation of overbank flood discharges
Authors: Williams J. J. R. , Stavropoulou Constantina 
Published: February 2007

AbstractA full computer based investigation of the factors influencing the modelling of overbank flood discharges has been carried out. Several floods of differing magnitudes and peak curvatures were routed down regular channels using an implicit finite difference scheme and the influence of time and distance steps used for the numerical solution of the flow equations were investigated.Spillage over sharp crested weirs was assumed to satisfactorily simulate the overbank flood discharge; the importance of a correct estimation of the coefficient of discharge was also checked. It was shown that sensibly chosen values of the time step had little effect on the simulations. This was also true for the value of the coefficient of discharge when the sideweir flow was predominately drowned, but not for free flow conditions. It was also shown that close spacing of computational nodes was required at the onset of overbank flow to accurately simulate the overflow and also model the occurrence of large water level gradients.
Vegetation change in the spray zone of a waterfall following river regulation in aurland, Western Norway
Authors: Odland Arvid , Birks Hilary H. , Botnen Astri , Tønsberg Tor , Vevle Odd 
Published: February 2007

AbstractA 25 m long transect was positioned along the spray gradient of a waterfall (880 m a.s.l.) in the Aurland River, western Norway. The vegetational composition in contiguous 1 m × 1 m quadrats was recorded in 1968 before regulation of the river, and again 20 years later. Spray precipitation, temperature, and humidity were also measured. The 92 per cent reduction in mean annual discharge of the river has resulted in a 98‐100 per cent reduction in spray precipitation along the transect. In general, there has been a great decrease in hygrophilous bryophytes and alpine vascular plants, and an increase in lichens and drought‐tolerant bryophytes. At the end of the transect furthest from the waterfall, which previously received less than 1200 mm of spray precipitation per year, there has only been minor floristic change. Similarly, in the nearest 5 quadrats, where spray precipitation is still substantial, there has been little change in the vegetation. The greatest change occurred in the middle of the transect which formerly received substantial amounts of spray, but is now almost dry.
The impact of river regulation on the lotic macroinvertebrate communities of the lower rhǒne, France
Authors: Fruget J. F. 
Published: February 2007

AbstractChannelization and the construction of 12 dams on the Lower Rhǒne during the last 30 years increased the morphological and biological effects of 19th century embanking along the river. These trends were demonstrated on the main channel, i.e. the central axis of the alluvial floodplain, by the synchronic study of the benthic macrofauna of six lowhead hydroelectric impoundments.The variability of the most significant taxa was investigated by an ANOVA, and the data‐samples matrix was processed with a Principal Components Analysis in order to analyse the communities organization and their significance. The benthic macroinvertebrate communities of the channel include some lentic potamic species topographically related with this kind of river (metapotamon), as well as eurytopic and pollution‐tolerant species. Thus, the Lower Rhǒne has become a slow potamic river, in the same way as other large mid‐European rivers. Flow velocity appears to be the most important structural factor in a large regulated river. The homogeneity of the macroinvertebrate communities and the absence of longitudinal typology show that, in a very intensely regulated river, the River Continuum Concept is too theoretical, and the disturbing effects of dams on longitudinal changes and species response to regulation must be taken into account.
Water mollusc communities and bioindication of lower salzach floodplain waters
Authors: Foeckler Francis , Diepolder Uschi , Deichner Oskar 
Published: February 2007

AbstractThe lower Salzach River lost its natural river dynamics as a result of channelization, which caused its bed to deepen, its groundwater table to be lowered, and its floodplains to gradually dry out. These changes of the floodplain have lead to a loss of natural biotopes with their biocoenoses. By using water mollusc communities as bioindicators these losses are detectable at a landscape level. A numerical analysis of a water mollusc survey in 1989 defined six water mollusc communities identifying six water‐body types: three flowing (streams, ditches, and rivers) and three standing (young former meanders, large deep groundwater‐influenced backwaters and small shallow groundwater‐influenced backwaters) within the lower Salzach valley. These communities and water‐body types are interpreted using results from water mollusc communities of other floodplain systems and by comparison with earlier water mollusc surveys in the lower Salzach valley. Then predictions are made on the future fate of the investigated floodplain water. Finally the investigated water bodies are evaluated for nature conservation in the face of plans to impound the lower Salzach River.
Coarse woody debris in stream channels in relation to river channel management in woodland areas
Authors: Gregory K. J. , Davis R. J. 
Published: February 2007

AbstractAlthough river channel management now generally uses soft rather than hard engineering techniques the considerable research achieved for woodland river channels has not been completely collated with reference to management implications. Research results from 22 research papers show how debris dams have a significant influence upon the morphological, the process and the ecological aspects of channels; vary in their permanence, and differ in stability according to the overall organic matter budget. A summary diagram contrasts the impact of dams on river channel morphology, process and ecology before and after dam removal. Four major types of specific recommendation about the management of channels in woodland areas are identified from 29 research papers are that (1) management should be undertaken against a background knowledge of the behaviour of coarse, woody debris under natural conditions and that the organic matter budget should be disturbed as little as possible; (2) logging operations should minimize the amount of disturbance to, and disruption of, channel processes; (3) management should optimize the maintenance of habitat diversity and minimize the ecological disturbance to the channel; (4) in some areas specific management practices may require the introduction of new material into the channel. These recommendations are applied to the New Forest, southern U.K., which has a long history of clearance and management of coarse woody debris and where the requirements for clearance in relation to fish, drainage, and aesthetic impact can be achieved by minimizing the amount of removal of material from the river channel. In managing channels with debris dams in woodland areas, it is desirable to work with the river in a holistic basin context.
Discontinuities in the distribution of invertebrates in impounded south island rivers, New Zealand
Authors: Harding Jon S. 
Published: February 2007

AbstractThe invertebrate fauna of 10 river systems, five with impoundments and five without, were sampled. No significant difference was found either in taxonomic richness or invertebrate densities between impounded and unimpounded sites at similar positions along river continua. However, plecopteran species richness was significantly lower and plecopteran density reduced in post‐impoundment sites. Densities of Deleatidium spp. (Ephemeroptera: Leptephlebiidae) were significantly lower at lake outlets compared with other sites. Two species of Zelandobius (Plecoptera: Gripopterygidae) and Eriopterini (Diptera: Tipulidae) snowed distributions apparently curtailed by impoundments, whereas Potamopyrgus antipodarum (Mollusca: Hydrobiidae) had an extended distribution. Margalef's, Menhinick's, Berger‐Parker and Shannon indices, total taxa present and plecopteran taxa were plotted against stream order, stream width and distance from the source. Menhinick's and Shannon‐Weaver indices produced statistically significant but weak regressions, and discontinuity distances and intensity could not be accurately calculated. The usefulness of diversity indices as a measure of the magnitude of impoundment effects in the South Island seems to be limited.
Hydromorphological consequences of regulating the lower vistula, Poland
Authors: Babiński Zygmunt 
Published: February 2007

AbstractQuantitative and qualitative data on channel changes along the lower Vistula arising from regulation works carried out in the 19th and 20th centuries are presented. Channel width was reduced by 50% and the bed lowered by 1.3 m. Changes of the river's hydrodynamic conditions in the segment from Wloclawek to Swiecie during the last 140 years are discussed. Changes of the bed load balance are characterized.