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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...
Ecohydrology presumes that physical external variables have a major influence on the biological components of an ecosystem and vice versa. The relationships between physical factors and biological components may be useful tools in environmental management. It requires, however, that these relationships are known quantitatively. It is only possible through the development of a proper model for the...
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...
Deteriorating environmental conditions and overexploitation in situations of insufficient fish stocking or a complete lack of it led to the extinction of salmon in Polish waters. The last population of salmon in the Drawa River disappeared in the mid-1980s. The aim of this work was to re-establish salmon in Polish waters. The salmon for this purpose came from the Daugava River, when in 1985 and 1987,...
The influence of littoral type at presence and absence of young of the year (YOY) pike (Esox lucius L.) on growth and diurnal behaviour of YOY pikeperch Stizostedion lucioperca (L.) was investigated in triplicate (7.5 m2) field enclosures. Three types of littoral zone were applied: with homogeneous macrophytes (HOM), with heterogeneous macrophytes (HEM) and with woody debris (WD), together with control...
This paper describes a deterministic age-structured dynamic pool model for floodplain-river fisheries. The model is applied to a heavily exploited floodplain fishery in north west Bangladesh to quantify the effects of hydrological modification and exploitation on production (catch per unit area) inside a typical flood control scheme, and to explore mitigating management interventions. Existing modifications...
Over the past centuries, rivers and streams across Europe and Northern America have increasingly been modified by damming and by other water regulation schemes. This situation is also becoming increasingly common throughout tropical regions. In the vast majority of cases, such schemes have been developed with little or no consideration to the ichthyofauna, and impacts on biodiversity and fisheries...
The Restoration Ecohydrology Concept integrates two approaches to restoration and mitigation of physically modified freshwater habitats. Firstly actions at the catchment level connected with integrated management of abiotic factors including, landscape planning, catchment management, forestation, phytotechnologies and hydrology by impoundment. Secondly actions at the level of the aquatic ecosystem...
The two ways of modification the oxygen conditions of dam reservoirs in order to protect fish from suffocation at freezing periods were presented: 1) the ice-hole size enlargement, and 2) short-term rises of a water level to raise oxygen concentration in the waters in fishes wintering sites. Both the methods are based on the modifications of the water flow through hydroelectric power stations as the...
Lake Kortowskie is restored by the hypolimnetic withdrawal method: rich in nutrients near-bottom waters are removed by a pipeline directly to the outflow instead of the natural outflow of surface waters. It has been found out that the amount of water discharged through the pipeline and therefore the amount of removed phosphorus depends on the surface inflow. The water balance of the lake in summer...
The task of optimal management of the dam reservoir ecosystem was formulated in a very abstract and general way. To solve this problem, on the simplified example of such an ecosystem, method of fuzzy logic was employed. Various scenarios of ecosystem management of dam reservoir has been investigated. Water level changes, inflow of waste waters and fish culturing were taken into consideration. It was...
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