bluuebunny/crossref_metadata_2025_split huggingface dataset:
Short‐term effects of local river restoration on morphology, flow field, substrate and biota
Authors: Habersack H. , Nachtnebel H. P. 
Published: February 2007

AbstractThe objective of this paper is to analyse the short‐term effects of restoration on river morphology, flow field, substrate and biota. One of the aims of the restoration measures is to arrest the degradation of the river Drau, which has caused technical (instability of bank protection measures) and ecological (loss of dynamic river reaches with alternate bars) problems. The restoration programme consists of several measures such as digging a new side channel on the right side, leaving an island and erection of groins on the left side of the main channel. These were made to keep the entrance open. After a two year monitoring programme the results of the analysis show that with respect to the river morphology, flow field and substrate, positive and negative effects were recorded, whereas for the ecology, positive effects were in general documented. Repeated morphological surveys using an echosounder showed that within a year without major flood events the main channel aggraded on average about 16 cm and the upper parts of the island degraded by up to 1 m. The groin pools became partially filled due to their function as sediment traps for finer material during low flows. Subsequent, measurements performed after several floods showed that degradation reduced the amount of aggradation by 50%. Flow velocity measurements demonstrated the effects of groins and their inability to force the main flow path to the side channel. In contrast with the main channel, the side channel was characterized by highly variable sediment grain sizes and dynamic morphological changes. The lower shear stresses and higher growth of algae in the side channel were associated with higher numbers of species of macroinvertebrates. Population studies showed significantly higher densities of fish species in this reach with a side channel than in any other river reach. Forty species of birds were observed, seven of which were typical water‐related species, and the number of plant species increased from 48 to 118.
Patial distribution of spiders on the floodplain of the river trent, UK: The role of hydrological setting
Authors: Greenwood M. T. , Bickerton M. A. , Petts G. E. 
Published: February 2007

AbstractInvertebrate communities provide sensitive indicators of physical stress, such as that imposed by moisture regime. With reference to two floodplain sectors—one non‐regulated and one regulated—on the River Trent, UK, this paper uses spider communities to characterize the dominant floodplain units (riparian, wetland, wet woodland, pasture and arable) and compares the information derived with a parallel data set from the groundbeetle community (F. Carabidae). The study yielded 77 spider species, of which 43 were common to the two floodplain sectors. Hypomma bituberculatum (wetland), Bathyphantes niginus (wet woodland) and Pachygnatha degeeri, Pardosa pullata and Trochosa ruricola (arable) showed restricted distributions and are regarded as ‘habitat specialists’. Species richness was highest in the wetland patches and lowest in the pasture. Differences between the faunal communities of the different habitats were greatest in the regulated sector. Spiders and beetles collected from the same traps are shown to provide different and complementary information on floodplain functioning, which may prove valuable in any ecological assessment.
River regulation in Southern China: Ecological implications, conservation and environmental management
Authors: Dudgeon David 
Published: February 2007

AbstractSouthern China—i.e. China south of the Chang Jiang (Yangtze River)—has a monsoon climate with pronounced wet and dry seasons and consequent effects on river discharge. There is considerable inter‐year variation in the duration and intensity of the monsoon, and the region experiences frequent floods and droughts which cause considerable human misery. The importance of floods as an incentive for river regulation is apparent from the fact that 10% of China's area, inhabited by 65% of the population and responsible for 70% of the agricultural and industrial output, is below the flood level of major rivers. Irrigation and hydroelectric power are additional benefits to be derived from river regulation. China has a 4000 year history of river regulation, but most of the changes that have been made to riverine environments have not taken account of the ecological consequences. This review considers the ecological implications of planned or existing schemes for the regulation of southern Chinese rivers. Particular attention is paid to the Chang Jiang and Zhujiang (Pearl River) which, by volume of discharge, are the two largest rivers in China. Large‐scale water‐transfer projects and the planned construction of the biggest dam in the world (the Three Gorges High Dam) on the Chang Jiang have the potential to affect fisheries stocks and endangered fish species, to alter inundation patterns in wetlands of international conservation significance and may contribute to the extinction of the endemic and highly endangered Chinese alligator (Alligator sinensis) and Chinese river dolphin (Lipotes vexillifer). In addition, deforestation and soil erosion in the Chang Jiang basin have given rise to siltation and degradation of floodplain habitats. In the Zhujiang, dam construction has caused reductions in fisheries stocks but here, as elsewhere in China, the ecologically damaging consequences of river regulation are exacerbated by overfishing and increasing pollution of rivers by sewage, pesticides and industrial wastes.
A perspective on dryland river ecosystems
Authors: Walker K. F. , Sheldon F. , Puckridge J. T. 
Published: February 2007

AbstractThe ecosystem concept should be reappraised as a basic model for rivers, with regard for flow as an organizing variable. This would facilitate comparisons between the large rivers of humid climates, where flow regimes are comparatively regular, and those of arid and semi‐arid areas, where river regimes are highly variable. Ecosystem processes might be modelled by combining the river continuum and flood pulse concepts, with refinements to accommodate a complex flood pulse (e.g. variations in stage amplitude, timing, duration, rates of rise and fall). Patch boundaries (ecotones) such as the riverine littoral zone warrant close study because they strongly influence the structure and dynamics of the ecosystem. The general model needs a quantitative basis, perhaps focused on the balance of processes involved in the physical transport and biological transformation of carbon. The ultimate test of such a model will be in its capacity to predict the effects of flow regulation. Further development, however, is limited by data. In both research and management monitoring programmes need to be established to provide information and to develop a sustained, comprehensive approach to dryland rivers as ecosystems.
Ecological connectivity in alluvial river ecosystems and its disruption by flow regulation
Authors: Ward J. V. , Stanford J. A. 
Published: February 2007

AbstractThe dynamic nature of alluvial floodplain rivers is a function of flow and sediment regimes interacting with the physiographic features and vegetation cover of the landscape. During seasonal inundation, the flood pulse forms a ‘moving littoral’ that traverses the plain, increasing productivity and enhancing connectivity. The range of spatio‐temporal connectivity between different biotopes, coupled with variable levels of natural disturbance, determine successional patterns and habitat heterogeneity that are responsible for maintaining the ecological integrity of floodplain river systems. Flow regulation by dams, often compounded by other modifications such as levee construction, normally results in reduced connectivity and altered successional trajectories in downstream reaches. Flood peaks are typically reduced by river regulation, which reduces the frequency and extent of floodplain inundation. A reduction in channel‐forming flows reduces channel migration, an important phenomenon in maintaining high levels of habitat diversity across floodplains. The seasonal timing of floods may be shifted by flow regulation, with major ramifications for aquatic and terrestrial biota. Truncation of sediment transport may result in channel degradation for many kilometres downstream from a dam. Deepening of the channel lowers the water‐table, which affects riparian vegetation dynamics and reduces the effective base level of tributaries, which results in rejuvenation and erosion. Ecological integrity in floodplain rivers is based in part on a diversity of water bodies with differing degrees of connectivity with the main river channel. Collectively, these water bodies occupy a wide range of successional stages, thereby forming a mosaic of habitat patches across the floodplain, This diversity is maintained by a balance between the trend toward terrestrialization and flow disturbances that renew connectivity and reset successional sequences. To counter the influence of river regulation, restoration efforts should focus on reestablishing dynamic connectivity between the channel and floodplain water bodies.
Comparison of summer zoobenthic communities in four habitats of a floodplain impoundment:1975 and 1990
Authors: Brewer Sandra K. , Claflin Thomas O. , Sandheinrich Mark B. 
Published: February 2007

AbstractThe diversity, evenness, similarity, standing crop and abundance of benthic macroinvertebrates in Navigation Pool 8 of the upper Mississippi River were compared in 1975 and 1990. Macroinvertebrates were collected in midsummer from four habitats: marsh, bay, open water and side channel. These habitat types accounted for 64% of the total habitat area in the impoundment. The community structure changed in all four habitats; the percentage similarities between 1975 and 1990 were lowest in open water (19%), intermediate in bays (44%) and side channels (50%) and highest in marshes (62%). Macroinvertebrate diversity and evenness were not significantly different between 1975 and 1990. The standing crop decreased in all habitat types. The abundance decreased in all habitats except bays between 1975 and 1990. The greatest changes in standing crop and community composition occurred in bays and open water. Because the bays and open water habitat comprise 55% of the total area, it is possible that these declines may signal degradation of the aquatic habitat in the entire reservoir. Changes in macroinvertebrate community structure and standing crop may have been due to unstable sediment conditions caused by erosion of islands, resuspension of sediments and loss of aquatic macrophytes and depth.
Bioassessment of contaminant transport and distribution in aquatic ecosystems by chemical analysis of burrowing mayflies (Hexagenia)
Authors: Steingraeber Mark T. , Wiener James G. 
Published: February 2007

AbstractBurrowing mayfly nymphs (Ephemeroptera) inhabit and ingest fine‐grained sediments and detritus that may be enriched with metals and persistent organic compounds. The burrowing nymphs can externally adsorb and internally assimilate these contaminants, providing a link for the food chain transfer of potentially toxic substances from sediments to organisms in higher trophic levels. The emergent adults are short‐lived and do not feed, thus their gut contents do not contribute greatly to their total contaminant burden. These characteristics make Hexagenia spp. and certain other burrowing mayflies useful for assessing ecosystem contamination. General protocols are presented for the collection, processing and analysis of emergent mayflies to assess the spatial distribution and bioaccumulation of sediment‐associated contaminants in aquatic ecosystems. Two essential components of this bioassessment approach are a network of on‐site volunteers with the materials and instructions needed to correctly collect and store samples and quality assurance procedures to estimate the accuracy of chemical analyses. The utility of this approach is demonstrated with an example of its application to the Upper Mississippi River (USA). Determination of cadmium, mercury and polychlorinated biphenyl congeners in emergent Hexagenia bilineata from a 1250km reach of this river revealed (1) several source areas of contaminants and (2) distinct patterns in the bioaccumulation (and apparent sediment‐associated transport) of each residue on both small and large spatial scales.
Habitat rehabilitation on the upper Mississippi River
Authors: Theiling Charles H. 
Published: February 2007

AbstractUpper Mississippi River ecological integrity has been severely compromised by human activity during the last 50 years. In response to the continuing decline of natural resource values, two approaches for protecting and improving the Upper Mississippi River‐floodplain ecosystem have been used. Habitat rehabilitation and enhancement projects are being constructed at 54 locations to provide site‐specific rehabilitation. The projects are designed to counteract the adverse ecological effects of sedimentation through (1) flow introductions, (2) the isolation of backwaters; and (3) flow diversions and wave breaks. Channel maintenance projects are being re‐evaluated in an attempt to construct or modify existing river training structures that are environmentally sympathetic. The latter approach works with the river's energy, whereas the former attempts to overcome riverine processes. Both approaches have significant limitations because they affect limited areas. A proposal is presented that restores some ecosystem integrity by re‐establishing occasional low river stages that occurred before the implementation of the Upper Mississippi River Navigation System.
Ecological integrity of aquatic systems
Authors: Cairns John 
Published: February 2007

AbstractFocusing on the ecological integrity of large river systems has suggested the rethinking of the entire issue from a landscape perspective. Ecological integrity is impossible without biological integrity. However, it appears improbable that highly localized measures of biological integrity can be used for effective, scientifically justifiable extrapolations to landscape‐ or system‐level ecological integrity. It may be more reasonable to make measurements at the level of organization of interest, i.e. larger spatial and temporal scales. In addition, human society and natural systems have been coevolving since the agricultural revolution and, arguably, well before then. Two types of coevolution between human society and natural systems appear possible: (1) an ‘arms‐race’ in which human society ignores changes in natural systems—essential ecosystem services are lost, resulting in unpleasant consequences for society; or (2) mutualism in which environmental literacy and a feeling of responsibility for natural systems motivate rapid societal response to ecosystem changes and the preservation of ecological integrity.The simplest measures of ecological integrity may be the actions of human society likely to minimize or markedly reduce negative impacts on natural systems. This does not mean substituting such measures for more customary ecological measures, but rather using both types of measurements simultaneously.
Hydrological connectivity and flood pulses as the central aspects for the integrity of a river‐floodplain system
Authors: Heiler Gudrun , Hein Thomas , Schiemer Fritz , Bornette Gudrun 
Published: February 2007

AbstractPreparations are currently under way to establish a river restoration concept for the free‐flowing section of the Austrian Danube downstream of Vienna. This should serve as a basis for a National Park management. Studies have been initiated to assess the effects of hydrological connectivity, flood pulses and successional processes on backwaters with regard to their hydrochemistry and suspended solid load. Water level fluctuations in the ground‐ and surface waters of the floodplain are dynamic because of the porous aquifer structure and several inflow areas. In a lateral transect, increasing distance from the Danube correlates with decreasing connectivity. Different influences in a longitudinal transect are due to the positions of the inflow areas. At low water level, the Danube and its backwaters have no surface connection. Internal processes determine the conditions within the backwaters, which are typically characterized by low concentrations of inorganic nutrients and particles versus the Danube. At higher water levels, local surface inflow and seepage water lead to periodic nutrient pulses and eutrophication. The input of inorganic nutrients and particles, as well as the flushing of phytoplankton during floods, establish an initial setpoint in the backwaters. The significance of flood pulses for the dynamics of biological processes is emphasized by short‐term changes, e.g. in the relationship between nutrients, inorganic particles and chlorophyll. The response in different water bodies depends on the grade of connectivity to the Danube.
River regulation and fish communities in the Murray‐Darling river system, Australia
Authors: Gehrke P. C. , Brown P. , Schiller C. B. , Moffatt D. B. , Bruce A. M. 
Published: February 2007

AbstractFish communities from four catchments in the Murray—Darling river system were analysed in relation to climate, hydrology and river regulation. Using the annual proportional flow deviation as a measure of river regulation, the Paroo River catchment was assessed as unregulated, the Darling River catchment as mildly regulated and the Murrumbidgee River and River Murray catchments as highly regulated. A total of 11010 fish, representing nine native and three alien species, was caught during high and low flow seasons in the four catchments. Native species, such as golden perch Macquaria ambigua (Percichthyidae), bony herring Nematalosa erebi (Clupeidae) and spangled perch Leiopotherapon unicolor (Teraponidae), dominated fish communities in the Paroo and Darling catchments, but alien species, mostly carp, Cyprinus carpio (Cyprinidae), were also abundant. Both native and alien species were more abundant in these catchments after flooding, but there was little change in species composition between high and low flow seasons at the catchment level. Carp dominated communities in the Murray and Murrumbidgee catchments. There was a significant trend for reduced species diversity in increasingly regulated catchments. River regulation may alter the relative abundance of native and alien fish by desynchronizing environmental cycles and the reproductive cycles of native species. Ordination of species abundances showed discrete fish communities that reflect the geographical separation between catchments. Differences between communities are related to opportunities for dispersal, the environmental tolerances of dominant species and the modifying effects of river regulation. Fish communities in lakes exhibited less seasonal variation than riverine communities within the same catchment, indicating the greater seasonal stability of lakes compared with regulated and unregulated river reaches. Management of fish resources needs to include catchment‐specific strategies within current State and basin‐wide management programmes.
Natural capital and the growth economy
Authors: Gowdy John M. 
Published: February 2007

AbstractIt is argued that the term ‘natural capital’ contains two contradictory ideas. The word ‘natural’ refers to a world governed by ecological relationships while ‘capital’ refers to a world governed by the laws of the market. Current efforts to place economic values on environmental goods are discussed. The inadequacy of using either standard economic approaches or approaches suggested by ecological economists to place market values on biodiversity is examined. Possible paths to environmental sustainability are discussed.
Greenhouse gas audit for western Australia
Authors: Blake Neil , Stocker Laura 
Published: February 2007

AbstractThe second greenhouse gas audit for Western Australia follows significant policy and scientific advances in the climate change arena. The United Nations Framework on Climate Change has been ratified by Australia and has been in force since March 1994. There are also policy implications leading from the discovery of the complex effects of secondary or ‘indirect’ global warming potentials of greenhouse gases, and the effects of the depletion of the ozone layer on the global warming. The present audit is based on the methodology of the Draft Australian Greenhouse Gas Emissions Inventory in order to be commensurate with national and international inventory work. There remain significant gaps in the audit information base. Some of these could be filled by further research while others would be filled by better cooperation from relevant government departments. The audit found that, despite some worthwhile efforts in energy conservation and recycling, most sectors have greatly increased their greenhouse gas emissions, in particular construction and electricity generation. Two exceptions were the transport sector which showed a very small increase in emissions, and the agriculture sector which showed a decline. An energy policy based on increased use of gas and renewables rather than coal would make a great contribution to greenhouse gas reductions and there are many opportunities for simple and cheap greenhouse gas reduction.
The control of industrial pollution: Implications for technology choice and growth
Authors: Alavi Hamid 
Published: February 2007

AbstractTo reduce pollution, industrial enterprises can cut production or choose cleaner technologies. A rise in demand increases marginal revenue and, for given plant sizes and costs, profits. Abatement cost can therefore coincide with marginal profits. If economic growth implies a rising demand, then growth can increase incentive to pollute because, other things equal, it makes abatement relatively more costly. The choice of cleaner technologies may be the alternative.Without official pollution control measures, profit‐maximizing enterprises will choose polluting technologies. The control measures themselves imply different choice of technologies. Effluent charges and polluter subsidies induce similar responses by an enterprise, but in a competitive industry, the former will yield lower output and pollution levels than would occur under subsidies. Moreover, in certain cases the command‐and‐control measures can be more effective than incentive‐based measures in controlling industrial pollution and promoting growth. A differential in information, monitoring and enforcement costs of different pollution‐control measures does not alter the results.
Enhanced environmental management: The case for conditional economic growthinldcs
Authors: Welch Richard 
Published: February 2007

AbstractA case is outlined for continued economic growth in LDCs contingent upon radical environmental repositioning by individual states. The argument rests on two premises: that LDCs would be interested in employing sustainable management practices but for the associated costs, and that current political, economic and environmental circumstances are such that DCs may now be inclined to help meet some of those costs. The article focuses on LDCs with levels of biodiversity which would suggest that they might derive immediate economic benefit from environmental repositioning, and outlines strategies which might be employed. Particular reference is made to the case of Papua New Guinea, geographically adjacent to the south east Asian region of environmental concern, and which might offer itself to the international community as a locus for empirical, economic‐environmental experiment.