bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of the abundance/biomass method for comparison of fish communities in regulated and unregulated lowland rivers in Belgium
Authors: Coeck J. , Vandelannoote A. , Yseboodt R. , Verheyen R. F. 
Published: February 2007

AbstractThe abundance/biomass comparison (ABC) method, proposed by Warwick (1986) for detecting pollution effects on marine macrobenthic communities, was tested on distribution patterns of numbers and biomass among fish species in regulated and non‐regulated lowland rivers in Belgium. The biomass and abundance of the fish populations were determined by electrofishing. The sample sites represent a range of physically disturbed watercourses, from natural meandering to heavily channelized reaches. Sites upstream and downstream from a polluting discharge were also evaluated. The physical habitat and water quality were measured on each site. Our data show a significant correlation between the qualitatively measured physical habitat and an ABC index, calculated from the ABC graph data. A significant correlation was also found between the pollution level and the ABC index. It is concluded that the ABC method is applicable to the assessment of disturbance in fish communities in rivers, and that the method gives information about both pollution and physical disturbance. The ABC method is a useful instrument to assess the status of a fish community before and after river channel works or natural and human induced river restorations.
Effect of habitat improvement on atlantic salmon in the regulated river suldalslågen
Authors: Raastad Jan E. , Lillehammer Albert , Lillehammer Leif , Kaasa Halvard , Eie Jon A. 
Published: February 2007

AbstractThe River Suldalslågen, which holds a population of large Atlantic salmon, has been regulated twice for hydropower production. The first regulation occurred in 1968 and the second in 1980. Present problems include the reduced density of benthic fauna, the reduced growth rate of young salmon, the low survival of 0+ fish and the increased time required for smoltification. A programme of habitat restoration includes building a rearing channel system where water flow and the substrate can be controlled. The salmon fry are stocked in the rearing channel and in an adjacent tributary stream. The effects on macrobenthos of introduced dead organic material were also studied. Improvement of physical habitat increased the density of benthic animals, and the survival of 1+ salmon was about 30%. Experiments that included adding of 115g wheat/m2 resulted in a threefold increase in benthic fauna compared with a control area. The largest increase in numbers was in Chironomidae in August‐September, when benthic Crustacea also showed a significant increase. An increase in macrobenthos is expected to increase the growth and survival of young salmon fry.
Efficiency of fishways and impact of dams on the migration of grayling and brown trout in the Glomma river system, south‐eastern Norway
Authors: Linløkken Arne 
Published: February 2007

AbstractThis study was carried out to assess the efficiency of eight fishways constructed in connection with hydroelectric dams in the Glomma river system in south‐eastern Norway. The fishways were of the pool and weir type, except for one which was of the counter current (Denil) type, and had a discharge of 0.5–1.0 m3/s. During 1985–8 3077 grayling and 2995 brown trout were captured in traps in the fishways, measured and floy‐tagged before being released in the river upstream of the fishways. The number of fish captured in two of the fishways were compared with estimated fish stocks in the areas around the fishways. Migrations began in May or June when the water temperature was > 5–6°C. Spawning migration of grayling occurred in May. During May more than 200 grayling may enter a single fishway within a week. In other fishways grayling occur only sporadically before late June or early July, when they migrate upstream to feed. Brown trout migrate during late spring, summer and autumn. The spawning migration takes place more or less during the whole summer, but mostly in late July and August. Immature brown trout also pass through the fishways, with a peak in October in three fishways. This migration is probably an ascending emigration from recruitment areas located downstream of these fishways. The efficiency of these fishways appears low, as the number of fish ascending was less than 2% of the estimated stock within the stretches where 90% of the recaptures occurred. The discharge in the fishway relative to the total discharge seemed to be of great importance, and to achieve efficient fishways they should be constructed for higher discharges, compared with river discharge, than the fishways in this area. The longest migration of grayling was 100 km, whereas the longest migration of brown trout was 122 km. The fish seemed to exploit shorter river stretches in areas influenced by several dams/fishways than fish in an area influenced by only one dam.
Flow regulation and restoration of Florida's Kissimmee river
Authors: Toth Louis A. , Obeysekera Jayantha T. B. , Perkins William A. , Loftin M. Kent 
Published: February 2007

AbstractChannelization of the Kissimmee River in central Florida destroyed or degraded most of the fish and wildlife habitat once provided by the river and its floodplain wetlands. Between 1984 and 1989 a demonstration project was conducted to evaluate the feasibility of restoring the river's biological resources. Reintroduction of flow through remnant river channels improved river channel habitat diversity and led to favourable responses by fish and invertebrate communities. However, results indicated that more complete restoration of biological attributes will require the re‐establishment of historical inflow characteristics. Owing to the flood control regulation schedule of its headwater lakes, current river discharge regimes are pulse‐like, include extended periods of low or no flow, and have high and low flow periods which are out of phase compared with typical seasonal patterns that occurred before channelization. These flow characteristics will preclude effective river restoration by contributing to chronic low dissolved oxygen regimes and repetitive fish kills, interfering with fish reproduction and limiting floodplain inundation. Simulation modelling was used to develop a modified headwater lakes regulation schedule which re‐establishes season flow patterns, smooths discharge peaks and maintains base flows for a greater portion of the year. Implementation of the new schedule, combined with extensive canal backfilling, will lead to discharge and stage characteristics that meet established criteria for achieving ecosystem restoration goals.
Physical habitat changes and macroinvertebrate response to river regulation: The river Rede, UK
Authors: Petts Geoff , Armitage Patrick , Castella Emmanuel 
Published: February 2007

AbstractDownstream variations of benthic macroinvertebrate communities on the River Rede below Catcleugh Reservoir, impounded in 1905, are related to a simple index of regulation magnitude, related to hydrological, water quality and trophic changes, and variations of channel morphology. The river is divided into five sectors on the basis of network morphometry and channel form. Channel change to flow regulation is confined to a short (1.6 km) reach immediately below the dam within which channel width and conveyance have been reduced by 53 and 75%, respectively. Downstream, siltation has occurred, but it is patchy and average levels of sediment finer than 2 mm are less than 10%. The main faunal responses — increased abundance and number of taxa — are also confined to the first sector below the dam. Ephemeroptera are shown to be the best describers of the downstream pattern. Variations of the fauna between riffles within sectors are shown to relate to site‐specific hydraulic conditions, especially bed shear stress.
Improvement of fish habitat in a Norwegian river channelization scheme
Authors: Brittain John E. , Eie Jon Arne , Brabrand Age , Saltveit Svein Jakob , Heggenes Jan 
Published: February 2007

AbstractTechniques for reducing adverse effects of river and lake regulation are being developed and tested within the framework of the Norwegian Biotope Adjustment Programme. The programme is illustrated by studies of a river flowing through the wetland area, Lesjaleirene, which has been drained and channelized to provide additional agricultural land. The channelized river has a homogeneous sand substrate. Experimental placement of rocks and stones increased brown trout densities, especially in areas in contact with the river banks. The new areas of rocks and stones provide cover for fish as well as a greater variation in depth and flow conditions.
Zooplankton population in the river tigris: Effects of samarra impoundment
Authors: Sabri Anmar W. , Ali Zainab H. , Shawkat Serwan F. , Thejar Lamia A. , Kassim Thaer I. , Rasheed Khalid A. 
Published: February 2007

AbstractThe influences of the Samarra impoundment on the ecology of the downstream sector of the river Tigris are investigated. Zooplankton were collected monthly from July 1987 to July 1988. It was found that zooplankton were most abundant during high river discharges in March. During the month of low river discharge, September, the zooplankton population was greatly reduced immediately below the barrage and remained so to the last downstream station. Several factors seem to explain such differences. The high discharge from the impoundment was found to be the dominating factor and may flush the small backwaters in which zooplankton were abundant, thus increasing the population in the river. Zooplankton species vary in their ability to sustain populations in the river, variations which are due mainly to species‐specific characteristics.
Stable carbon and nitrogen isotope analysis of seston in a regulated Rocky Mountain river, USA
Authors: Angradi Ted R. 
Published: February 2007

AbstractThe δ13C and δ15N of seston, organic matter sources (riparian vegetation, algae, macrophytes, plankton) and an invertebrate detritivore were examined in a regulated Rocky Mountain river (fourth order). The isotopic composition of seston varied among sites and seasons for all size fractions; among‐site variation was weakest for ultra‐fine particulate organic matter (< 53 μm). Comminution of seston to ultra‐fine size partially obscured isotopic differences among sites. Multiple isotope signatures of seston were distinct among sites at different distances from a dam (0.5, 5.3, 8.7 km) and between the river and a third order tributary. Seston (> 53 μm) from 0.5 km below the dam was relatively 13C‐depleted (−30 to −28°), reflecting the contribution of reservoir‐derived plankton; seston from the site 8.7 km downstream was relatively 13C‐enriched (−18 to −23°), reflecting autochthonous inputs. Tributary seston had an intermediate δ13C value (−22 to −26°), reflecting allochthonous inputs (conifer litter) and macrophyte (Elodea) detrital inputs. δ15N values of seston were generally similar among sites (4–8°) but were more depleted for the tributary (1–4°). Depleted δ15N values (0–2.5°) for seston from below the dam in late summer corresponded to a blue‐green algae bloom in the reservoir. Isotopic shifts of organic matter incubated for 60–90 days in situ were small (< 2°) and varied in direction depending on isotope and litter type. The isotopic composition of stonefly larvae, Pteronarcys californica, varied among sites, and closely matched that of the local seston (especially FPOM), suggesting that with respect to detritus origin, larvae were opportunistic foragers. The origin of organic matter is influenced by flow regulation, resulting in compressed isotopic gradients.
Application and testing of a procedure to evaluate transferability of habitat suitability criteria
Authors: Thomas Jeff A. , Bovee Ken D. 
Published: February 2007

AbstractA procedure designed to test the transferability of habitat suitability criteria was evaluated in the Cache la Poudre River, Colorado. Habitat suitability criteria were developed for active adult and juvenile rainbow trout in the South Platte River, Colorado. These criteria were tested by comparing microhabitat use predicted from the criteria with observed microhabitat use by adult rainbow trout in the Cache la Poudre River. A one‐sided X2 test, using counts of occupied and unoccupied cells in each suitability classification, was used to test for non‐random selection for optimum habitat use over usable habitat and for suitable over unsuitable habitat. Criteria for adult rainbow trout were judged to be transferable to the Cache la Poudre River, but juvenile criteria (applied to adults) were not transferable. Random subsampling of occupied and unoccupied cells was conducted to determine the effect of sample size on the reliability of the test procedure. The incidence of type I and type II errors increased rapidly as the sample size was reduced below 55 occupied and 200 unoccupied cells. Recommended modifications to the procedure included the adoption of a systematic or randomized sampling design and direct measurement of microhabitat variables. With these modifications, the procedure is economical, simple and reliable. Use of the procedure as a quality assurance device in routine applications of the instream flow incremental methodology was encouraged.
Particulate organic matter transport in the lower Colorado river, South‐Western USA
Authors: Lieberman Davine M. , Burke Thomas A. 
Published: February 2007

AbstractThe lower Colorado River from Laughlin, Nevada, to the border with Mexico is one of the most regulated rivers in North America. An analysis of particulate organic matter (POM) transport through the system was made to determine POM concentrations, composition and point of origin, as well as to determine the effect dams had on this transport. Particulate organic matter concentrations generally increased from upstream to downstream, and were dominated by very fine organic detritus (< 25μm size fraction). Reservoirs released more POM than they received during spring and summer, but less during autumn and winter. Reservoirs recycled POM, taking in organic detritus and discharging small limnoplankton. Backwater complexes functioned as filters during storm events, trapping coarse material and releasing fine material. Agricultural drains made only minor contributions of POM, but provided important nutrients for in‐channel production of POM. Water diversions forced POM off‐channel, whereas sluicing operations reduced inorganic loads in the canals. Despite the presence of six mainstem dams, the lower reaches support a diverse assemblage of detritivorous fishes, similar to that found in the lowermost reaches of natural, unregulated rivers. The food base for this fishery stems from autochthonous production of POM.
Dissolved organic carbon dynamics in the upper rhone: The influence of side‐arms?
Authors: Cellot B. , Rostan J. C. 
Published: February 2007

AbstractDissolved organic carbon (DOC) dynamics were investigated over a two year period in the Upper Rhǒne River to examine the role of side‐arms in providing DOC to the main channel in relation to discharge fluctuations, especially floods. Concentrations of DOC are shown to remain low in space and in time (average 1.5 mg −1) and to be more related to global hydrological events (precipitation) than to any local flushing for backwaters during floods. The results do not support the general assumption that side‐arms are the providers of DOC to the main channel.
Vertical distribution of coarse particulate organic matter in river bed sediments (Morava river, Czech Republic)
Authors: Rulík Martin 
Published: February 2007

AbstractThe vertical and temporal distribution of coarse particulate organic matter (CPOM) larger than 1 mm from 0 to 70 cm depth within the substrate was observed at two different sites along a riffle in the River Morava. Samples of hyporheal sediments were taken by inserting a steel cylinder and a special grab. The amount of CPOM was determined by combustion. The maximum amount of CPOM was found at a depth of 30‐40 cm; lower levels of CPOM were observed in deeper horizons. The average amount of CPOM in 10cm layers (volume 1582.9 cm3) was 232.2 gm−3 at station A and 691.3 gm−3 at station B. The content of CPOM showed a maximum during the summer.
Alteration of patch boundaries on the floodplain of the regulated river trent, UK
Authors: Large A. R. G. , Prach K. , Bickerton M. A. , Wade P. M. 
Published: February 2007

AbstractInvestigations were carried out into the contemporary distribution and structure of the vegetation communities at Gunthorpe, Nottinghamshire on the floodplain of the River Trent. A 60 km reach of the river was examined to determine the overall distribution and structure of vegetation communities; the Gunthorpe site was chosen as a representative example. Three hundred and thirty‐nine separate plots were examined and the site contained 132 species. It is clear that the extent of zones of discontinuity or transition (ecotones) between different vegetation patches has decreased due to long‐term land‐use management. The overall number of vegetation patches has also been reduced. A hierarchy relating boundaries to external influences is proposed and the relationship of ecotones to more clearly differentiated patch habitats identified. Highest species diversity is seen to be associated with the transition zones or ecotonal habitats, particularly under conditions of moderate disturbance intensity. It is concluded that the ecotones remaining still provide a habitat for a wide range of species with differing autecological requirements, but all typical of less disturbed alluvial meadows and marshes. These zones of transition potentially provide a pool for species expansion given improved ecological conditions following river restoration measures.
Application of mobile acoustic techniques fish surveys in shallow water: The river seine
Authors: Guillard Jean , Boet Philippe , Gerdeaux Daniel , Roux Philippe 
Published: February 2007

AbstractMobile acoustic techniques (echo‐sounding and echo‐integration) for fish surveys were used in shallow waters of depths less than 5 m. These techniques show the importance of fish biomass in the side‐channels and the detection of echoes in the main channel. Diurnal spatial migrations are seen. The advantages and limitations of the method as a complement to traditional sampling methods in the river are examined.
Determination of ecologically acceptable flows in rivers with seasonal changes in the density of macrophyte
Authors: Hearne John , Johnson Ian , Armitage Patrick 
Published: February 2007

AbstractThe Instream Flow Incremental Methodology (IFIM) is a procedure that has been applied to the rivers of many countries to determine the relationship between discharge and a measure of the physical habitat area available to aquatic species. PHABSIM is a software package that is used to perform the calculations required for the IFIM procedure. Published data on instream macrophyte growth in chalk streams are used here to test the seasonal effects of plant growth in a hypothetical channel. The results show how these effects can significantly distort PHABSIM results. The predicted weighted useable area can differ by as much as 34% depending on the season used for the principal calibration of the Water Surface Profile module (WSP) of PHABSIM. An algorithm is proposed for use with PHABSIM which allows the effects of changes in macrophyte biomass to be included.
Hydraulic study of a two‐stage river channel
Authors: Myers W. Robert , Lyness John F. 
Published: February 2007

AbstractMany regulated rivers have compound or two‐stage cross‐sections consisting of a deep main channel flanked by one or two floodplains. Existing methods of assessing discharge capacity in such channels can lead to serious errors, and hence there is a need for the acquisition of flow data to validate models suggested as improvements to existing methods. Stage and discharge data, under both steady and unsteady conditions, were collected from a reach of the River Main in Northern Ireland, which has been reconstructed for flood defence purposes to form a two‐stage channel. The data were analysed using a steady flow computational model to yield water surface profiles and values of Manning's resistance coefficient at various flow depths. The complex nature of flow resistance in two‐stage channels is demonstrated. Unsteady stage hydrographs were linked to a computational model which illustrates the magnitude of errors incurred in applying conventional methods of discharge estimation in compound rivers.
Effects of draining and desilting a small weir on downstream fish and macroinvertebrates
Authors: Doeg T. J. , Koehn J. D. 
Published: February 2007

AbstractDraining a small off‐take weir in February 1991 before desilting introduced large amounts of sediment (at least 100m3) into the downstream creek. Increased suspended solids concentrations up to 4610 mg/l were recorded downstream during the release. Large volumes of sand were deposited close to the weir, with finer fractions (silt) deposited up to 2 km further downstream. Very fine silt was washed through the system to a major river 4.5 km below the weir. Over the first day of the release, at a site 2.1 km below the weir, there was a reduction of 19.4% in the total number of benthic macroinvertebrate taxa, and average reductions of 63.9% in the abundance of and 39.7% in the number of taxa per sample. Over the following 45 days the fauna recovered towards pre‐release diversity and density. This recovery was not sustained and further reductions in diversity and abundance were recorded over the following five months, probably due to fresh disturbance from desilting works and further mobilization of sediment during high flows. A major storm and flood in September 1991 apparently flushed all additional silt from the creek and the macroinvertebrate fauna subsequently recovered to higher diversity and density levels than before the release.Compared with densities recorded in 1985 and 1988, the population of river blackfish (Gadopsis marmoratus) was reduced by 93% after the release at a site 250m downstream of the weir, with reductions of 81 and 59% at distances from the weir of 2.1 and 2.7 km, respectively. An additional reduction in this fish population occurred at the lower site in late 1991, probably due to further flushing of sediments during the September flood. Although reductions in fish numbers occurred across the whole population, greater reductions were recorded for the younger age classes. Small subsequent increases in fish numbers at upper sites during 1992‐1993 indicated that a recovery of the blackfish population may be occurring through recruitment, but such a recovery will only be confirmed over the long term.