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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...
Natural riverine ecosystems are characterized by a high level of heterogeneity manifest across a range of spatio-temporal scales. Ecotonal habitats are both the result of and contributors to the spatio-temporal dynamics of riverine ecosystems. Natural disturbances play an important rôle in maintaining a diversity of ecotonal habitats. A typology of riverine ecotones is developed that provides an expansive...
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...
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...
Today’s management of agricultural areas is hardly in accordance with actual economic and ecological goals. In view of the future risks for the global system a revolutionary change within our current land use systems is essential. The paper gives an example of a workable strategy for agricultural policy baded on the internalization of external burdens into a market price system as well as the expansion...
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 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...
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