ISSN:0886-9375    

DOI:10.1002/rrr.3450060202

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

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

ISSN:0886-9375    

DOI:10.1002/rrr.3450060203

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractIn response to a noticeable decline in recreational fishing in the formerly productive Larto—Saline backwater complex of east central Louisiana, a study was begun to identify causative factors for the decline and to determine effective methods to remedy the problem. To this end, water quality and fisheries surveys were conducted in the system for the study period 1 July, 1981 to 30 June, 1989.Data collected during the early years of the study indicated chronically high turbidity (>100 FTU) to be the major factor limiting game fish production. The high turbidity can be related to man‐made alterations of natural flood patterns that had changed the major source of backwater flooding from Black River to the highly turbid Red River.In September, 1986, a construction project was undertaken to restore flood patterns to approximate natural conditions. Sampling subsequent to this construction has shown a significant decrease in turbidity and an increase in game fish product

ISSN:0886-9375    

DOI:10.1002/rrr.3450060204

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractUse and development of rivers takes place within a complex legal framework that guides the actions of interested parties holding conflicting values. One of the major components of this legal framework is state water allocation law. This law takes several forms among the states, but its basic function is to establish rules for water use by assigning property rights in water. Another component of the legal framework for river use addresses the public access issue. The primary focus here is establishment of the boundary between the exclusive rights of landowners and the rights of the general public to use the surface and underlying beds of waterways. A third component consists of governmental controls over water use and development. These controls restrict the exercise of private property rights in the resource. From an initial focus of protecting the public right of navigation, this law has expanded to include protection of water quality and a variety of other environmental values. The current legal framework provides a relatively sound basis for balancing competing values and interests, but problems exist. For example, the division of water management responsibilities between the federal and state levels of government sometimes results in conflict, and existing procedures for managing conflict related to proposals for water transfer do not appear to be adequate. Therefore, the current framework will not remain static; it must continue to evolve in order to operate more effectively and to incorporate future increases in knowledge and the associated changes in values and management needs.

ISSN:0886-9375    

DOI:10.1002/rrr.3450060205

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractWe collected water‐quality data from 15 artificial floodplain ponds along the Mississippi River during May 1988 and quantified shoreline length, shoreline sinuousity, volume, and depth variation. Ponds regarded as high‐quality nurseries (based upon larval fish densities) contained higher dissolved oxygen concentrations and lower total organic carbon concentrations than ponds of lower nursery quality (p<0.02). High‐quality nurseries also maintained higher conductivity and turbidity than low‐quality nurseries (p<0.05). Results indicated that dissolved oxygen and pH probably fluctuated less in high quality nurseries and therefore provided better conditions for survival and growth of larval fishes. Total organic carbon and conductivity were directly related to pond morphometry (p<0.004) and affected dissolved oxygen and pH in ponds. Large, high‐volume ponds with sinuous shorelines and variable depths tended to contain both high conductivities and low total organic carbon concentrations. Pond morphometry may have affected water quality and subsequently determined the nursery value of artificial floodpl

ISSN:0886-9375    

DOI:10.1002/rrr.3450060206

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractWater level regulation has been proposed as a tool for maintaining or enhancing fish and wildlife resources in navigation pools and associated flood plains of the Upper Mississippi River System. Research related to the development of water level management plans is being conducted under the Long Term Resource Monitoring Program. Research strategies include investigations of cause and effect relationships, spatial and temporal patterns of resource components, and alternative problem solutions. The principal hypothesis being tested states that water level fluctuations resulting from navigation dam operation create less than optimal conditions for the reproduction and growth of target aquatic macrophyte and fish species. Representative navigation pools have been selected to describe hydrologic, engineering, and legal constraints within which fish and wildlife objectives can be established. Spatial analyses are underway to predict the magnitude and location of habitat changes that will result from controlled changes in water elevation.

ISSN:0886-9375    

DOI:10.1002/rrr.3450060207

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractA study of aquatic habitat types was undertaken in August 1989 on the River Great Ouse. Habitat character at 44 sites was evaluated via twelve qualitative and quantitative environmental variables. Discriminant Analysis of the environmental data revealed a weak discrimination of sites corresponding with longitudinal changes in channel width. Distinction between the habitat types in the analysis was relatively weak. Compared with unregulated European lowland rivers of similar geomorphological origin, the Great Ouse possesses little transversal habitat diversity (abandoned channels, oxbows, etc.) and the ponding effect of water retention structures in downstream sections appears to have created a slight longitudinal gradient in channel width and depth. This comparatively low habitat heterogeneity corroborates a previous report of limited recruitment in the Great Ouse by 0 + fishes of both limnophilous and rheophilous reproductive guilds, with a predominance of generalist spawners.

ISSN:0886-9375    

DOI:10.1002/rrr.3450060208

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractBiological indicators may signal changes in freshwater quality but offer little information on long‐term trends in ecosystem succession. As an improvement over biological indicators in river management we propose the use of ‘functional describers’, abiotic and biotic elements that reflect alterations in ecosystem function and succession through changes in their concentration or abundance, including the appearance and/or extinction of organisms or groups of organisms. Juvenile (0 +) fishes have been found to be useful functional describers in many fluvial situations encountered in Europe, not least because the ontogeny of European fishes is strongly reflected in the type of habitat chosen for reproduction. Using the regulated River Rhǒne, France, as an example, the absence or presence of 0 + juveniles is shown to provide a direct reflection of a biotope's potential as a spawning area, particularly if recent hydrological conditions have not facilitated 0 + fish displacement and the lone presence of a predator species has not suggested the elimination of other fish species. Identification of the ecological function and successional state of a fluvial ecosystem is aided by consideration of species reproductive styles and tolerances. When time, labour, and/or funding is limited, the function and succession of numerous biotopes within a catchment or large fluvial system can be monitored cost effectively by analysing the 0 + fishes assemblages via the functional describer ap

ISSN:0886-9375    

DOI:10.1002/rrr.3450060209

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0886-9375    

DOI:10.1002/rrr.3450060201

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY