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1	Winter Habitat Selection Of Cutthroat Trout (Oncorhynchus clarki) In A Large Regulated River Englund, Ronald A. 01 May 1991 (has links) Microhabitat use by cutthroat trout and macrohabitat use by both cutthroat and rainbow trout were studied i n the Green River below Flaming Gorge Dam during the winters of 1988 and 1989. Microhabitat parameters used by cutthroat trout, such as focal velocity, depth, and fish elevation, differed significantly in eddies, runs, and riffles. Mean focal velocities in runs were 0.79 body lengths/seconds (bl/s), in riffles 0.66 bl/s, and in eddies 0.24 bl/s. Cutthroat trout size also varied significantly with macrohabitat; larger fish were found in riffles. Macrohabitat use by cutthroat trout and rainbow trout differed significantly among species, macrohabitat types, and months. Both rainbow trout and cutthroat trout macrohabitat use shifted from lower velocity habitats during winter to faster velocity habitats in summer. Cutthroat trout and rainbow trout used macrohabitats at seasonally differing rates. Riffles were never selected in proportion to their abundance, especially during high winter discharges. Cutthroat trout implanted with radiotransmitters exhibited little movement during diel monitoring and did not change their occupation of macrohabitats. winter habitat cutthroat trout oncorhynchus clarki regulated river Aquaculture and Fisheries
2	Impact of hydropower regulation on river water geochemistry and hyporheic exchange Siergieiev, Dmytro January 2013 (has links) Hydropower regulation of rivers exhibits a threat to the riverine ecosystems. Fragmentation of flow, landscape disturbances, and water retention are key features of regulated catchments, resulting in reduced floods and geochemical tr¬ansport, non-natural water level fluctuations, and thus disturbed exchange between the river and the aquifer. Storing of water in reservoirs reduces peak flow and turbidity, which increases particle settling and sometimes favours enhanced primary production and formation of a clogging layer. This in turn alters the interaction between surface water and groundwater, with potential secondary effects on the entire watershed. In Scandinavia, only eight large rivers (16%) remain entirely unregulated. The Lule River, the primary focus of this study, belongs to the most regulated rivers of Eurasia with a degree of regulation (i.e. the volume of water that can be stored in the reservoirs and used for regulation) of 72%, and is exposed to both seasonal and short-time regulation.Using hydrogeochemical analysis of two adjacent boreal rivers (pristine Kalix and regulated Lule River) discharging into the Gulf of Bothnia, the effects of regulation on river geochemistry were investigated. For the Lule River, the average maximum runoff was almost halved while the average minimum runoff was tripled as a result of the regulation. The winter transport fraction of total organic carbon, Fe, Si, suspended Mn and P in the Lule River was at least two to three times higher than in the pristine river. During summer, the suspended C/N ratio in the regulated river was 10-20, compared to <10 for the pristine river, suggesting a presence of predominantly decaying organic material due to longer residence times for the regulated river. This was supported by a virtually constant suspended P/Fe ratio throughout the year in the Lule River, indicating low abundance of phytoplankton. Hence, a pronounced impact on the ecosystem of the river, the hyporheic/riparian zone, and the Gulf of Bothnia is expected.In spite of vast anthropogenic pressure on riverine ecosystems, the knowledge regarding the hyporheic zone (the interface between rivers and aquifers where exchange between surface water and groundwater occurs) is limited for regulated rivers. Therefore, this study was extended to also cover the hyporheic exchange along the Lule River. Temporal changes in hyporheic fluxes across the river channel (rates and directions) were determined using seepage measurements and continuous observations of water stages, temperatures, and electrical conductivity for both the river and the groundwater. While the river water level changed frequently (typically twice a day with up to ± 0.5 m), the river remained gaining 90% of the time, and the largest number of observed changes in flow direction (observed at 5 m orthogonal distance from the river) was six times per week. Flow velocities ≤10-4 m d-1 ( zero flow) constituted 1.5% of the total observation time.Although no changes in water temperature were observed for the hyporheic zone, effects of river level variations were detected up to 5 m inland, where electrical conductivity occasionally decreased to surface water levels indicating infiltration of river water into the aquifer (negative fluxes). River discharge regulation may therefore have severe implications on biogeochemical processes and deteriorate the hydroecological functions of the hyporheic zone. regulated river hyporheic zone hydraulic conductivity clogging layer Geochemistry Geokemi
3	Hydrological control of plant species composition and distribution in Dal River alluvial meadows Jimel, Matouš January 2023 (has links) Northern boreal alluvial meadows are ecologically significant semi-natural ecosystems within the riparian zone. The effects of disturbance like flooding, grazing, and mowing have historically maintained high nutrient turnover and succession disruption that led to high biodiversity, leading to their inclusion in the Natura 2000 network. Today, alluvial meadows are threatened by human abandonment and river flow regulations, both of which provided necessary disturbances. This leads to encroachment by woody plants and a significant reduction in biodiversity. The purpose of this project was to investigate the hydrological conditions required for the long-term maintenance of floodplains of the regulated lower Dal River and how varying water levels affect the species distribution and various vegetation characteristics. This was done by examining plant data from 3 sites in an alluvial meadow in Bredforsen and datalogger water level data to calculate the duration of flooding of plots in a transect study. The effects of altitude, flooding durations, and frequencies on species richness, proportion of woody plants, and vegetation cover were examined. Flooding times showed the most significant effects on vegetation characteristics, while altitude and flooding frequencies differed greatly between sites, with variability explained being low for all explanatory variables. On one hand, this shows that that a lack of seasonal flooding has a negative effect on the alluvial meadow ecosystem and an increase in water flow would be beneficial. On the other hand, the low degree of explained variability implies that flooding solely is not the determining factor and other management methods are necessary to maintain the alluvial meadows. Riparian zone Alluvial meadows Riparian vegetation Regulated river Flooding Ecology Ekologi
4	Re-establishment of connectivity for fish populations in regulated rivers Calles, Olle January 2005 (has links) <p>The hydropower industry has altered connectivity in many rivers during the last century. Many fish species depend on both an intact longitudinal connectivity to be able to migrate between spawning, feeding and winter habitats, and vertical connectivity for development and survival of incubating embryos and larvae in the gravel. The objective of this thesis was to examine problems and remedial measures associated with disrupted longitudinal and vertical connectivity in regulated rivers. The issue of longitudinal connectivity was studied in the River Emån by evaluating the efficiency of two nature-like fishways for anadromous brown trout. Telemetry studies showed that the combined efficiency for the two fishways in 2001-2004 was 60.5%. The passage efficiencies of both fishways were high for trout (89-100%), but also for other species such as chub, perch, tench, burbot and roach (74%). The attraction efficiencies were largely dependent on power plant operation, and generally high for the fishway situated next to the tail-race and low for the fishway situated inside the former channel. More than half of the trout spawners were also observed using the fishways for downstream passage. The densities of brown trout yearlings upstream of the fishways were higher after the fishways were built than during pre-fishway years. Smolts produced upstream of the fishways were observed migrating downstream in 2003-2005. The percentage of smolts that passed both power plants in was 51%, with losses being attributed to predation (15%), turbine-induced mortality (16%) and other reasons (18%). Turbine-induced mortality was higher (40%) at the power plant with four small Francis runners, than at the power plant with one large Kaplan runner (12%). The issue of vertical connectivity was studied in three rivers in Värmland, one unregulated, and two regulated, one of which had no minimum flow requirements. In the unregulated river, temporal patterns in hyporheic water chemistry correlated to variation in surface water chemistry and discharge as expected. In the regulated rivers, the hyporheic water chemistry showed little correlation to discharge or surface water chemistry. The intra-gravel water chemistry conditions for brown trout eggs were more favourable in the unregulated river, characterised by high oxygen levels, than in the two regulated rivers. The regulated river with no minimum flow requirements had critically low oxygen levels at the end of the incubation period.</p> Attraction efficiency Connectivity Flow regime Hyporheic water quality Nature-like fishway Passage efficiency Regulated river Remedial measures Salmo trutta Biology Biologi
5	Re-establishment of connectivity for fish populations in regulated rivers Calles, Olle January 2005 (has links) The hydropower industry has altered connectivity in many rivers during the last century. Many fish species depend on both an intact longitudinal connectivity to be able to migrate between spawning, feeding and winter habitats, and vertical connectivity for development and survival of incubating embryos and larvae in the gravel. The objective of this thesis was to examine problems and remedial measures associated with disrupted longitudinal and vertical connectivity in regulated rivers. The issue of longitudinal connectivity was studied in the River Emån by evaluating the efficiency of two nature-like fishways for anadromous brown trout. Telemetry studies showed that the combined efficiency for the two fishways in 2001-2004 was 60.5%. The passage efficiencies of both fishways were high for trout (89-100%), but also for other species such as chub, perch, tench, burbot and roach (74%). The attraction efficiencies were largely dependent on power plant operation, and generally high for the fishway situated next to the tail-race and low for the fishway situated inside the former channel. More than half of the trout spawners were also observed using the fishways for downstream passage. The densities of brown trout yearlings upstream of the fishways were higher after the fishways were built than during pre-fishway years. Smolts produced upstream of the fishways were observed migrating downstream in 2003-2005. The percentage of smolts that passed both power plants in was 51%, with losses being attributed to predation (15%), turbine-induced mortality (16%) and other reasons (18%). Turbine-induced mortality was higher (40%) at the power plant with four small Francis runners, than at the power plant with one large Kaplan runner (12%). The issue of vertical connectivity was studied in three rivers in Värmland, one unregulated, and two regulated, one of which had no minimum flow requirements. In the unregulated river, temporal patterns in hyporheic water chemistry correlated to variation in surface water chemistry and discharge as expected. In the regulated rivers, the hyporheic water chemistry showed little correlation to discharge or surface water chemistry. The intra-gravel water chemistry conditions for brown trout eggs were more favourable in the unregulated river, characterised by high oxygen levels, than in the two regulated rivers. The regulated river with no minimum flow requirements had critically low oxygen levels at the end of the incubation period. Attraction efficiency Connectivity Flow regime Hyporheic water quality Nature-like fishway Passage efficiency Regulated river Remedial measures Salmo trutta Biology Biologi
6	Avledning av öringsmolt (<em>Salmo trutta</em>) från turbinintag / Diversion of trout smolts (<em>Salmo trutta)</em> from turbine intakes Engqvist, Thérèse January 2009 (has links) <p>Vattenkraftstationer, med dammar och turbiner, utgör hinder för nedströmsvandrande smolt. Syftet med denna studie var att undersöka turbindödligheten för öringsmolt (<em>Salmo trutta)</em> vid två kraftstationer, de befintliga ytlänsarnas avledningseffekt och om effekten kunde förstärkas genom mörkläggning i form av övertäckning av kraftkanalen med en presenning vid turbinintaget. Utöver detta var avsikten även att undersöka om det fanns något samband mellan smoltgrad och smoltens förmåga att förflytta sig mot havet. I Emån i Småland fångades 46 öringsmolt som radiomärktes och sattes ut vid två kraftstationer och pejlades dagligen i sex veckor. Det var en större dödlighet vid den övre stationen än vid den nedre. Ytlänsen vid den nedre stationen hade en klart avledande effekt, men inte ytlänsen vid den övre stationen. Samtliga smolt som valde passage via isutskovet, gjorde det när kraftkanalen vid turbinintaget var övertäckt med presenning (d.v.s. ljusintensiteten minskades kraftigt). Det gick inte att påvisa någon skillnad mellan låg och hög smoltgrad eller tidig och sen utsättning för fördröjning vid den ena kraftstationen, inte heller för förflyttning efter de två kraftstationerna.</p> / <p>Hydropower plants, with dams and turbines, form obstacles to smolts migrating downstream. The purpose of this study was to investigate turbine-induced mortality of brown trout (<em>Salmo trutta</em>) smolts at two power plants, guidance efficiency of existing diverters and whether the effect was enhanced by reducing light levels at the turbine intake by covering the power plant channel with an opaque tarpaulin. Furthermore, the aim was to investigate whether there was a relationship between smolt status and the smolts’ ability to move towards the sea. In the River Emån in Småland 46 trout smolts were caught, radio-tagged, released at two power plants and tracked daily for six weeks. There was a higher mortality at the upper power plant than at the lower one. The diverter at the lower power plant had a statistically significant guiding effect, but the diverter at the upper power plant did not. All of the smolts that chose passage through the trash gate did so when the power channel was covered with tarpaulin (i.e. light levels were greatly reduced). There was no evidence that smolt status or release date would affect passage times at the upper station, nor did smolt status affect swimming speeds downstream of the two power stations.</p> / Cost-Benefit Analysis of River Regulation diversion smolt smolts trout telemetry radiotelemetry migration mortality hydropower turbine turbines trash gate Salmo trutta regulated river turbine-induced mortality power station power stations diverter diverters smolt status light manipulation downstream migration wolf trap trap cover opaque tarpaulin migration problems radio tag avledning smolt öring Emån Finsjö pejling reglerat vattendrag telemetri radiotelemetri radiomärkning vandring dödlighet mortalitet migration vattenkraft turbin turbiner isutskov Salmo trutta vandringshinder turbindödlighet kraftstation kraftstationer ytläns ytlänsar smoltgrad smoltstatus ljusmanipulation nedströmsvandring träfälla fälla radiosändare övertäckning presenning mörkläggning Biology Biologi
7	Avledning av öringsmolt (Salmo trutta) från turbinintag / Diversion of trout smolts (Salmo trutta) from turbine intakes Engqvist, Thérèse January 2009 (has links) Vattenkraftstationer, med dammar och turbiner, utgör hinder för nedströmsvandrande smolt. Syftet med denna studie var att undersöka turbindödligheten för öringsmolt (Salmo trutta) vid två kraftstationer, de befintliga ytlänsarnas avledningseffekt och om effekten kunde förstärkas genom mörkläggning i form av övertäckning av kraftkanalen med en presenning vid turbinintaget. Utöver detta var avsikten även att undersöka om det fanns något samband mellan smoltgrad och smoltens förmåga att förflytta sig mot havet. I Emån i Småland fångades 46 öringsmolt som radiomärktes och sattes ut vid två kraftstationer och pejlades dagligen i sex veckor. Det var en större dödlighet vid den övre stationen än vid den nedre. Ytlänsen vid den nedre stationen hade en klart avledande effekt, men inte ytlänsen vid den övre stationen. Samtliga smolt som valde passage via isutskovet, gjorde det när kraftkanalen vid turbinintaget var övertäckt med presenning (d.v.s. ljusintensiteten minskades kraftigt). Det gick inte att påvisa någon skillnad mellan låg och hög smoltgrad eller tidig och sen utsättning för fördröjning vid den ena kraftstationen, inte heller för förflyttning efter de två kraftstationerna. / Hydropower plants, with dams and turbines, form obstacles to smolts migrating downstream. The purpose of this study was to investigate turbine-induced mortality of brown trout (Salmo trutta) smolts at two power plants, guidance efficiency of existing diverters and whether the effect was enhanced by reducing light levels at the turbine intake by covering the power plant channel with an opaque tarpaulin. Furthermore, the aim was to investigate whether there was a relationship between smolt status and the smolts’ ability to move towards the sea. In the River Emån in Småland 46 trout smolts were caught, radio-tagged, released at two power plants and tracked daily for six weeks. There was a higher mortality at the upper power plant than at the lower one. The diverter at the lower power plant had a statistically significant guiding effect, but the diverter at the upper power plant did not. All of the smolts that chose passage through the trash gate did so when the power channel was covered with tarpaulin (i.e. light levels were greatly reduced). There was no evidence that smolt status or release date would affect passage times at the upper station, nor did smolt status affect swimming speeds downstream of the two power stations. / Cost-Benefit Analysis of River Regulation diversion smolt smolts trout telemetry radiotelemetry migration mortality hydropower turbine turbines trash gate Salmo trutta regulated river turbine-induced mortality power station power stations diverter diverters smolt status light manipulation downstream migration wolf trap trap cover opaque tarpaulin migration problems radio tag avledning smolt öring Emån Finsjö pejling reglerat vattendrag telemetri radiotelemetri radiomärkning vandring dödlighet mortalitet migration vattenkraft turbin turbiner isutskov Salmo trutta vandringshinder turbindödlighet kraftstation kraftstationer ytläns ytlänsar smoltgrad smoltstatus ljusmanipulation nedströmsvandring träfälla fälla radiosändare övertäckning presenning mörkläggning Biology Biologi

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