ISSN:0886-9375    

DOI:10.1002/rrr.3450060402

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

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

ISSN:0886-9375    

DOI:10.1002/rrr.3450060403

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe macrobenthos (especially Chironomidae) along channel margins has been compared for two 5th‐order rivers, the River Grabia, which has not changed its morphology for many years, and the River Widawka, which experienced an increase of channel width (by over 5 m) about eight years before the present study due to human impact. Also, the effect of frequent short‐term high water levels on the macrobenthos near the bank was investigated in the 7th order section of the Warta River downstream of a dam.The macrobenthos distribution was found to be similar in the ‘impacted’ Warta and Widawka Rivers, with the highest abundance near the bank, decreasing towards the mid‐channel. In the marginal zone of the Widawka River, abundant detritivorous invertebrates having low oxygen tolerance (mainly Prodiamesinae and Chironomini) were observed. The percentage of Chironomini in this zone of the Warta River was even higher than that in the Widawka River. A different pattern was observed in the ‘natural’ Grabia River—the lowest species number and density were at the banks: Orthocladiinae dominated especially in the mid‐river.A high abundance fluctuation of one of two dominant species in the margin of the Warta River—Glyptotendipes gripekoveniK. is remarkable. The larvae temporarily reached high densities on snags, which were periodically exposed and submerged by water, although over a year their density was lower (399 ind m−2) than that of those inhabiting the

ISSN:0886-9375    

DOI:10.1002/rrr.3450060404

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe river systems of the Rhine and Meuse include a large number of floodplain waters showing differences in hydrology and geomorphology. A classification of 100 water bodies based on their macroinvertebrate communities has been worked out as a tool for ecological management. Analyses were performed on structural (species composition) and functional (trophic relations) aspects of macrozoobenthos in relation to hydrological, vegetational, and physicochemical parameters. Based on the classification of macroinvertebrate communities, three major groups of water bodies can be distinguished, which are related to the frequency of inundation. The flood frequency constitutes the major environmental gradient which structures the zoobenthos communities in the Dutch floodplain waters. Faunal composition is mediated by substrate availability, water chemistry, and the availability of nutritional resources. This typology serves as a basis for the prediction of the impact of hydrology changes on the macrozoobenthic communities of floodplain waters of highly eutrophic and polluted rivers.

ISSN:0886-9375    

DOI:10.1002/rrr.3450060405

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractMacrozoobenthos (especially gastropods) abundance data have been used to ordinate sampling stations on two floodplains of the Upper Rhine with different hydraulic regimes: 30 species of gastropods were recorded in the area actively inundated by the Rhine, while backwaters that have not been flooded for over 50 years housed only 19 species.Potamopyrgus antipodarumis a characteristic species of the permanent aquatic biotopes fed by groundwater and connected with other floodplain waters. Small, isolated, and drying‐up former lateral channels and pools, slowly inundated during a flood, are characterized byPlanorbis planorbiswithBathyomphalus contortus. Gyralus albusandValvata cristataare characteristic of small, partly isolated, and partly drying‐up water bodies of the active floodplain, which are inundated rapidly and very turbulently during the flood. Due to restricted hydrological dynamics the waterbodies of the former floodplain were mainly inhabited by ubiquitous spec

ISSN:0886-9375    

DOI:10.1002/rrr.3450060406

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe study examines the relationship between floodplain aquatic macroinvertebrates and sector‐scale parameters such as geomorphology and history of regulation. The assemblages of six groups of invertebrates (Molluscs, Crustaceans, Ephemeroptera, Odonata, Trichoptera, and Coleoptera) were compared in various types of former channels from two contrasting but adjacent floodplain sectors: (1) the Jons sector of the Rhǒne River where successive meandering and braiding phases has left diversified fluvial forms in the landscape but where the main river is now embanked, and (2) the unregulated Ain River sector where the river is still actively meandering, although this process is being slowed by incision. The results demonstrate little difference in faunalcompositionbetween the two sectors but a significant difference in faunalstructure. In the Rhǒne floodplain, there was a clear distinction between the faunal assemblages together with a high taxa richness at the scale of the sector (dominance of the beta diversity). In the Ain floodplain, the faunal assemblages were overlapping and the taxa richness was high at the sample scale (alpha diversity). Sector‐scale spatial patterns of the faunal assemblages along former channels were also distinct:between‐channelheterogeneity dominated in the Rhǒne, whereaswithin‐channelheterogeneity dominated on the Ain. These results stress the influence of geomorphological and historical determinants on the floodplain communities and, conversely, the relevance of macroinvertebrate assemblages for the assessment, at the landscape scale, of aquatic systems within the f

ISSN:0886-9375    

DOI:10.1002/rrr.3450060407

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

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 Salzac

ISSN:0886-9375    

DOI:10.1002/rrr.3450060408

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractOn the basis of investigations on carabids along the Weser and some tributaries, ponds, and secondary habitats in gravel‐pits, the composition and spatial distribution of carabid communities are described: 132 carabid species were found in riverine habitats of the Weser floodplains near Höxter/Holzminden (FRG) and the relationship of selected species to grain‐size and coverage of vegetation are documented. Some typical carabid communities of mid‐European river ecosystems are present along the Weser, but the species and their few, mostly relic, habitats as well as secondary habitats in gravel‐pits are endangered. A long‐term and area‐oriented habitat management is necessary to protect and to develop the autochthonous c

ISSN:0886-9375    

DOI:10.1002/rrr.3450060409

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractFollowing a long history of floodplain degradation, directly or indirectly as a result of river regulation, international attention is turning to the restoration of these ecologically important ecotones. One immediate problem is to assess the ecological value of different floodplain habitats. With reference to two floodplain sectors—one non‐regulated and one regulated—on the River Trent, U.K., this paper characterizes the dominant floodplain units using two families of beetles (Coleoptera: Carabidae and Staphylinidae). Five dominant habitat units, riparian, wetland, woodland, pasture, and arable, are clearly differentiated by both families using ordination analyses. Although the faunal assemblages of specific units within the two sectors have many similarities, the units within the regulated sector are more clearly differentiated, having larger assemblages of ‘describer’ species. It is suggested that the enhanced environmental gradients between units within this sector may be responsible for stronger faunal

ISSN:0886-9375    

DOI:10.1002/rrr.3450060410

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractGravel banks with sparse vegetation are typical habitats of braided alpine and dealpine floodplains. They are not only habitats for semiaquatic or hygrophilous organisms, but include also xerophilous elements: 17 species of grasshoppers were recorded in the floodplain of the Upper Isar (Bavaria, FRG). In the alpine region, two species (Bryodema tuberculata, Chorthippus pullus) occuronlyin floodplains, colonizing young gravel banks with sparse vegetation. Population dynamics and habitat selection ofBryodema tuberculata, studied on the Upper Isar for several years, are characterized by small scale movements of marked individuals between neighbouring gravel banks and fluctuations of the abundance on different sections of the gravel banks. Furthermore, the periodic desiccation of small watercourses is important for the dispersal of the females by walking. Historically widespread, today its distribution corresponds to the few remaining inundation areas. The main causes of decrease and extinction in most localities are man‐made changes in floodplain dynamics. The building of retention reservoirs and the diverting of streams for hydropower influenced succession in the downstream floodplains. Most of the gravel banks with sparse vegetation changed into willow thickets or pine forests. All remaining inundation areas should be protected.Bryodema tuberculatais a good indicator for the balance between progressing succession and the reorganization of gravel banks by flood

ISSN:0886-9375    

DOI:10.1002/rrr.3450060411

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY