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The paper questions the usefulness of the static concept of the habitat as a templet in analyses of the influence of the riparian environment on the dynamics of riverine fish assemblages. Studies on the effect of deforestation on the water quality and invertebrate assemblages in upland streams in mid-Wales found that changes in the nature of the riparian habitat caused by logging had relatively few...
The roach preferred branches of spruce and juniper as artificial spawning substratum rather than pine and birch. Perch preferred birch over conifers. Thus altering the availability of spawning substrata in the littoral zone should be effective in controlling the density and structure of juvenile roach and perch communities in reservoirs. Density dependent processes affects the early life history of...
To test the role of riparian ecotones in fish community dynamics three different sites along the Sorraia system, were selected. Each station has been under distinct anthropogenic pressure, and characterized by a mosaic of habitat conditions. Fish were collected by electrofishing from October 1991 to October 1993 using two distinct sampling scales, (50 m and small sectors defined according to discontinuities...
Number of species (S), density (N) and standing crop (B) were investigated in 331 sites in the catchment of the Narew River, the biggest tributary of the Vistula, against 4 categories of riparian ecotone intensity in various-width rivers. All populations were first analyzed together, then within the scope of three most abundant ecological spawning groups. The image obtained is to some extent blurred...
The effect of riparian ecotone functional complexity and stream hydraulics on an upland river ecosystem has been analysed. The amount of nutrients retained by the bottom sediment was lowest on a sandy substrate and highest in wetland bays. A stream bed covered by Berula erecta had about three times higher nutrient retentive capacity than did a sandy substrate. The trophic potential of CPOM, measured...
The investigations were carried out in the lacustrine-fluvial system of the Lizhma river (the Ladoga lake basin) in its natural condition (until 1993) and during the exploitation of its trout complex. The authors show the water bodies to increase their content of biogenic elements at the expense of the organic form. They mark some changes in the structure of algoflora. The abundance of alkophylic...
This review summarises some results of investigation carried out by Russian scientists, concerning the influence of land/inland water ecotones on fish. The main objectives and hypotheses developing in the framework UNESCO MAB working group "Fish and land/inland ecotones" in Russia are: comparison of fish population in salmonid rivers affected or non-affected by lake-rivers ecotones; small...
Riparian ecotones are either within the bankfull lines (instream ecotones) or beyond (bank vegetation and floodplains). Instream ecotones (e.g. gravel bars) are most intimately and permanently interconnected with the stream system. The third order river Melk was channelized some decades ago with devastating effects on the fish fauna. The restoration of instream ecotones and of the riparian vegetation...
Authors present the hypothesis that freshwater fish diversity, recruitment and production depend greatly on riparian ecotones. These boundary environments are usually the most diverse elements of aquatic systems. Riparian ecotones moderate the transfer of energy and materials from the land, provide a high load of organic matter including invertebrate food, and moderate competition and predation among...
The last free stretch of the River Paraná inside of Brazilian territory, about 230 km of the former 810 km, runs in a wide floodplain, which flood regime is controlled in part by upstream dams. Aim to evaluate the impacts of different levels of hydrological control on the regional fish diversity, nutritional condition, trophic categories proportion, reproduction and young abundance monthly sampling...
The dramatic depletion of diversity and standing crop of freshwater fish has been due mostly to degradation of their habitats and water quality. To halt and reverse this negative trend, a new approach is needed urgently toward sustainability of fish resources. The UNESCO MAB programme on the role of land-water ecotones has opened a new perspective towards solving problems in landscape management and...
This paper characterizes the fish community and its interaction with different ecotones within the reservoir. The transformation of a river basin into a cascade of reservoirs produces new ecotones which interact differentially with the spatial\temporal distribution of fish species, their diversity, trophic structures, etc. So the variations of the fish fauna are described to understand better the...
According to heterozygosity, allele number, and Correspondence Analysis, the chub populations of the lentic Saone River were genetically homogeneous while those of the lotic Rhone River (including flowing sections and standing backwaters) were diverse. These two groups of populations were distant by 150 km.
A reduction of inflow to the Guadiana River on the border between Portugal and Spain may directly contribute to the degradation of fish habitats. Changes are expected to the spawning behaviour of Engraulis encrasicolus adults, to the migration patterns of larvae in the estuary, and to the catches of fisheries in the lower part of the river and adjacent coastal areas. Spawning of E. encrasicolus occurs...
Fish are heavily influenced by the nature of the flood regimes of the rivers in which they live. These fluctuate naturally from year to year but recently increasing pressure on water for a wide range of uses other than fisheries has led to human activities that have substantially altered the flood regimes of many rivers throughout the world. This has resulted in the loss of fish production and biodiversity...
Apart from their basic role as fish farming reservoirs, carp ponds have an important influence on water circulation and thus on water resources in the catchment basin. The positive influence of carp ponds as storage reservoirs results from the rearing cycle which corresponds with the hydrological cycle and consists in limiting high water-flows in the summer and increasing low water-flows in the autumn...
The data obtained within the framework of a survey of macrozoobenthos and fish communities in Czech streams of the Danube and Elbe river basins were evaluated with respect to the relation between biodiversity and level of water (organic pollution) and/or physical habitat quality (heterogeneity, substrate, riparian vegetation, canalisation). The diversity of macrozoobenthos species was the highest...
The occurence of 0+ juvenile fish was observed using a point abundance sampling strategy in non-flooded borrow pits, flooded borrow pits, oxbows and backwaters in the flood plain of the River Dyje in August 1998 and 1999. The season of 1998 was characterized by a shorttime managed flooding compared to a long-time managed flooding in 1999. Totally we registered the occurrence of 19 species of 0+ juvenile...
Hydroacoustical methods due to their very high resolution in time and space can be used to register subtle changes in fish distribution and behaviour, thus enabling observation of the effect of habitat modification upon the fish. A number of examples have been presented which show dependence between fish parameters measured acoustically (such as depth, density, degree of aggregation, length frequency...
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