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An analysis of the hierarchy of importance of point and diffuse phosphorus sources in the Lomnice River catchment for the eutrophication of Orlík Reservoir
Hejzlar, Josef ; Polívka, Josef ; Žaloudík, Jiří
P sources in the Lomnice River catchment were analysed in two ways: (i) with a balance method of comparing P fluxes at monitored profiles on streams against the sums of partial P sources within their catchments that was reduced by P retention in the stream network and (ii) with the SIMCAT model of the Environmental Agency UK. Both methods appointed as the main source of high concentrations of total P (i.e., mean and 90% percentile of 0,28 and 0,45 mg/l, respectively, at the mouth of the Lomnice River to Orlík Reservoir in 2004-2008) municipal wastewater discharges and intensive fish pond production (55 and 25 % of P sources in the catchment, respectively) while the exports from agricultural and forested areas were 15 and 3 %, respectively. Scenario calculations by both methods indicated that the level of P concentration in the Lomnice River without eutrophication impacts on the reservoir cannot be achieved without measures both in the purification of wastewaters and fisheries.
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Concentrations and forms of phosphorus in the runoff from small agricultural catchments in the catchment of Orlík Reservoir
Richtr, J. ; Hejzlar, Josef ; Semančíková, E.
Concentrations of major P forms were monitored in the runoff from 21 small agricultural catchments with dominant arable land or grassland within the basin of Orlík Reservoir during one seasonal cycle. Mean concentrations of dissolved reactive P (DRP) and dissolved non-reactive P (DNP) were low and not differed at the arable land and grassland catchments (DRP 32 and 24 μg/l, DNP 8 and 9 μg/l, respectively). Particulate P (PP) concentrations varied significantly between these two types of catchments (77 and 20 μg/l, respectively). Apparently, PP did not originated from recent erosion of land surface but from sediment resuspension or bank erosion in streams. Significant relationships between P concentrations in oxalate extracts of upper (0–15 cm) and deep (50–70 cm) soil layers and between the phosphate saturation index in the 50–70 cm soil layer and the DRP concentration in runoff demonstrated existence of relationship between soil available P and P concentration in catchment runoff.
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Phosphorus – the main cause of currently unfavourable state of eutrophication and water quality in Orlík Reservoir
Hejzlar, Josef ; Matěna, Josef ; Šimek, Karel ; Turek, Jan ; Znachor, Petr ; Žaloudík, Jiří ; Rohlík, V. ; Langhansová, M.
Inflow concentration and water retention time are major controlling factors for in-lake P concentration and consecutively development of water blooms and eutrophication. Orlík Reservoir has been hypertrophic in its inflow arms and eutrophic at the dam. For avoiding cyanobacteria blooms it is needed to decrease P load in the reservoir to less than one half. P-source apportionment in the catchment indicated the dominant importance of municipal wastewaters, farmland runoff, and fishpond production.
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Impacts of eutrophication on water quality in reservoirs: an assessment of nutrient inputs from catchment and of the anti-eutrophication resistance of reservoir ecosystem
Hejzlar, Josef ; Duras, J. ; Staňková, B. ; Turek, Jan ; Žaloudík, Jiří
The paper describes a methodology for the identification and quantification of nutrient sources in catchments (i.e. mainly point and diffuse sources, fishpond production, atmospheric deposition, natural background export) and for the determination of critical loads of reservoirs with nutrients, which are prerequisite for proposing of effective anti-eutrophication measures in reservoirs. An application of this methodology at the drinking water reservoir of Mostiště and its catchment showed that the results are in agreement with alternative methods of catchment nutrient sources assessment, e.g. ratio analysis among land use characteristics and stream water quality and/or direct determination of nutrient export from agricultural land with exclusion of other sources.
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How shall we study the fish stock of our large water reservoirs?
Kubečka, Jan ; Matěna, Josef ; Čech, Martin ; Draštík, Vladislav ; Frouzová, Jaroslava ; Hohausová, Eva ; Jarolím, Oldřich ; Jůza, Tomáš ; Kratochvíl, Michal ; Muška, Milan ; Peterka, Jiří ; Prchalová, Marie ; Říha, Milan ; Tušer, Michal ; Vašek, Mojmír
Quantitative fish stock assessment recently advanced significantly in the Czech Republic. Sampling of open water was facilitated by application of scientific echosounders, trawls, Nordic multimesh gillnets, purse seines and booming electoshockers. Simplified combination of the above methods was recommended for the monitoring of larger stagnant water the Water Framework Directive of EU. Combination of all above approaches with more classic ones (beach seining, benthic gillnets) is being used for „complex fish stock assessment“ providing the assessment of abundance, biomass, species and age composition of all important species in all important habitats of the reservoirs. Further improvements of results is likely to be achieved by the application of multibeam acoustic cameras and by mitigation of the problems connected with quantitative trawling of large fish
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Sampling of the offshore fry fish communities of reservoirs by trawls
Jůza, Tomáš ; Kubečka, Jan ; Čech, Martin ; Draštík, Vladislav ; Jarolím, Oldřich ; Peterka, Jiří ; Vašek, Mojmír
The offshore area of six Czech reservoirs was sampled by pelagic fry trawl in late summer in 2003-2005. In Římov, Želivka, Vrané and Slapy reservoirs cyprinids dominated in offshore area. The main species here were roach, bream and bleak. In Lipno and Nýrsko reservoirs percids dominated in offshore area (Lipno-pikeperch, Nýrsko-perch). Trawling in offshore areas revealed that almost all 0+ fish were caught in the surface stratum (0-3m depth). In reservoirs where percids and cyprinids occured together, cyprinids dominated in 0-3m depth while percids usually prevailed in catches of 0+ fish from 3-6m depth. In ordinary canyon-shaped reservoir like Římov and Želivka the 0+ fish abundance decreased from the upstream end toward the dam, so the biggest abundance was in tributary area. In cascade reservoirs like Slapy and Vrané, the offshore area in tributary is almost without fish. The peak of abundance is more downstream and from this place, the trend is similiar to non-cascade reservoirs.
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Fish diversity and spatial distribution of YOY fish in Vlatava cascade reservoirs
Draštík, Vladislav ; Kubečka, Jan ; Jůza, Tomáš ; Jarolím, Oldřich ; Hladík, Milan ; Kratochvíl, Michal ; Prchalová, Marie ; Říha, Milan ; Tušer, Michal
Fish communities of YOY were studied in four cascade reservoir by beach fry-seining and fry trawling. Highest fish fry density was found in Slapy and Vrané reservoir. Lowest density was found in Kamýk and Štěchovice reservoir, two small reservoirs with shortest retention time, lowest oxygen concentration and temperature. Pelagic fish fry assemblages had much lower density than littoral assemblages and follow general fish longitudinal gradient. Littoral assemblages were more difficult to interpret due to more factors which can play important role in fish fry spatial distribution (such as bottom substrate and slope, complexity of shoreline, availability of water vegetation). Cyprinid species (bleak (.i.Alburnus alburnus./i.), roach (.i.Rutilus rutilus./i.), bream (.i.Abramis brama./i.)) prevailed in most reservoirs, only in Kamýk reservoir percid species (perch (.i.Perca fluvitilis./i.), ruffe (.i.Gymnocephalus cernua./i.)) prevailed.
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Species composition along the vertical gradietn in canyon-shaped reservoirs
Prchalová, Marie ; Kubečka, Jan
During years 2004 and 2005, vertical gradients of fish distribution within two canyon-shaped Czech water supply reservoirs (Římov, Švihov) were examined by Nordic multimesh gillnets in both pelagic and benthic habitats. In the open water, most fish were found in the upper 5 m of depth. Below this depth nearly no fish occurred. The community was represented mainly by bleak. Towards deeper parts the portion of perch increased. In benthic areas, most fish were in the upper 3 m of depth. Abundance declined to 10 m and below this depth nearly no fish were present. Perch and roach dominated the littoral community. Ruffe preferred the deeper habitats. With respect to biomanipulative removal catches, it is sufficient to fish in the upper 5 m of the open water and in the upper 3 m in the littoral of the reservoir. For getting a rough but adequate assessment of fish community, it is satisfactory to sample the upper 5 m of the open water and the upper 10 m in the benthic part of the reservoir.
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