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Rodrigues, Michele de Medeiros. "Caracter?sticas limnol?gicas e estrutura tr?fica das comunidades de peixes de alguns lagos naturais e artificiais do Rio Grande do Norte." Universidade Federal do Rio Grande do Norte, 2007. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12516.
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Artificial lakes must differ from natural lakes in important structural and functional aspects that need to be understood so that these ecosystems can be properly managed. The aim of this work was to test the hypothesis that the artificial lakes (impoundments) in the semi-arid region of the Rio Grande do Norte State are more eutrophic and turbid and have different trophic structure when compared to the natural coastal lakes that occur in the humid eastern coast of the State. To test this hypothesis, 10 natural lakes and 8 artificial lakes with about 100 ha were sampled between September and November 2005 for the determination of some limnological variables and the abundance of the main fish species, which were grouped in three trophic guilds: facultative piscivores, facultative planktivores and omnivores. The results show that the artificial lakes had significantly higher concentrations of total nitrogen, total phosphorus, chlorophyll a , total and volatile suspended solids than the natural lakes. Results also show that the values of pH, total alkalinity, electric conductivity, turbidity as well as the coefficient of vertical attenuation of light were significantly higher in the artificial lakes than in the natural lakes. In the artificial lakes, the abundance of facultative planktivores was significantly higher, while the abundance of facultative piscivores significantly lower than in the natural lakes. There was no significant difference in the abundance of omnivorous fish between the two types of lakes. These results suggest that the increase in turbidity together with the other changes in the water quality of the artificial lakes, modifies the trophic structure of the fish communities reducing the importance of piscivores and the length of the food chains
Lagos artificiais devem diferir de lagos naturais em importantes aspectos estruturais e funcionais que precisam ser compreendidos para que possamos manejar adequadamente esses ecossistemas. Este trabalho foi realizado com o objetivo de testar a hip?tese de que os lagos artificiais (a?udes) na regi?o semi-?rida s?o ambientes mais eutrofizados e t?rbidos que possuem uma estrutura tr?fica distinta dos lagos costeiros naturais que ocorrem no litoral leste ?mido do Estado do Rio Grande do Norte. Para testar esta hip?tese, 10 lagos naturais e 8 lagos artificiais com cerca de 100 ha foram amostrados entre setembro e novembro de 2005 para determina??o de algumas vari?veis limnol?gicas e da abund?ncia das principais esp?cies de peixes, as quais foram agrupadas em tr?s guildas tr?ficas: pisc?voros facultativos, planct?voros facultativos e on?voros. Os resultados mostram que os lagos artificiais apresentaram concentra??es significativamente maiores de nitrog?nio e f?sforo total, clorofila a e s?lidos totais e vol?teis em suspens?o do que os lagos naturais. Os resultados tamb?m mostram que o pH, a alcalinidade total, a condutividade el?trica, a turbidez da ?gua e coeficiente de atenua??o vertical da luz nos lagos artificiais foram significativamente maiores do que nos lagos naturais. Nos lagos artificiais, a abund?ncia de peixes planct?voros facultativos tamb?m foi significativamente maior, enquanto que a abund?ncia de peixes pisc?voros facultativos foi significativamente menor do que nos lagos naturais. N?o houve diferen?as significativas na abund?ncia de peixes on?voros entre os dois tipos de lagos estudados. Esses resultados sugerem que a maior turbidez da ?gua aliada a outras mudan?as na qualidade da ?gua dos lagos artificiais eutrofizados afetam a estrutura tr?fica das comunidades de peixes reduzindo a import?ncia dos peixes pisc?voros e conseq?entemente o comprimento das cadeias alimentares
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Klemedsson, Shicarra. "Flocculation of natural organic matter in Swedish lakes." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-85118.
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Flocculation is an important part of the carbon cycle. It is therefore crucial to understand how flocculation is regulated and how different environmental factors impact. A dilemma is that it has been found difficult to measure flocculation experimentally. In this thesis, flocculation of dissolved organic carbon in a Swedish lake was measured in a series of laboratory experiments. The method used was Dynamic Light Scattering (DLS). DLS is used to determine the size distribution profile of, for instance, small particles in suspension. DLS measures Brownian motion and relates it to the particle size by measuring the fluctuation in scattering intensity. It is not very effective to measure the frequency spectrum contained in the intensity fluctuations directly, so instead, a digital auto correlator is used. Since factors such as pH, salinity and calcium chloride content varies in lakes and is thought to have an impact on flocculation, this was investigated as well. As pH was changed in a range of 3 to 9, small changes in size distribution could be detected. Salinity and calcium chloride content have quite an impact on flocculation. Time also has a great impact, samples that were set to rest for a week showed a significant increase in particle size. For DLS to work, the samples need to be filtered of centrifuged to get rid of large particles. Different types of filters were tested to see which filter material was the best to use. When filtering the water we only want to filter out the large particles. Natural organic matter has a hydrophobic component which adsorbs to some filter types but not to others. It is crucial to know which filters this hydrophobic component adsorbs to, so that the loss of dissolved organic carbon during filtration can be minimalized.
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Balangoda, Anusha. "Impact of Artificial Aeration on Nutrients in Small Eutrophic Lakes." Diss., North Dakota State University, 2014. http://hdl.handle.net/10365/24669.
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Stoffle, Richard W., Nieves Zedeño, Genevieve D. Hefley, and Fabio Pittaluga. "Ojibway Natural Resource Use In the Western Great Lakes." Bureau of Applied Research in Anthropology, 2013. http://hdl.handle.net/10150/293758.
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A presentation on the traditional resource use by Ojibway in the Western Great Lakes region. The complete report, which can be found in this collection, is titled 'Traditional Ojibway Resources In The Western Great Lakes.'
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Komen, Anita Louise. "A reconnaissance natural hazard assessment of Lakes Lyndon, Coleridge and Tekapo." Thesis, University of Canterbury. Geological Sciences, 2008. http://hdl.handle.net/10092/1781.
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The Canterbury Region is susceptible to a variety of natural hazards, including earthquakes, landslides and climate hazards. Increasing population and tourism within the region is driving development pressures and as more and more development occurs, the risk from natural hazards increases. In order to avoid development occurring in unacceptably vulnerable locations, natural hazard assessments are required. This study is a reconnaissance natural hazard assessment of Lakes Lyndon, Coleridge and Tekapo. There is restricted potential for development at Lake Lyndon, because the land surrounding the lake is owned by the Crown and has a number of development restrictions. However, there is the potential for conservation or recreation-linked development to occur. There is more potential for development at Lake Coleridge. Most of the land surrounding the lake is privately owned and has less development restrictions. The majority of land surrounding Lake Tekapo is divided into Crown-owned pastoral leases, which are protected from development, such as subdivision. However, there are substantial areas around the lake, which are privately owned and, therefore, have potential for development. Earthquake, landslide and climate hazards are the main natural hazards threatening Lakes Lyndon, Coleridge and Tekapo. The lakes are situated in a zone of active earth deformation in which large and relatively frequent earthquakes are produced. A large number of active faults lie within 15 km of each lake, which are capable of producing M7 or larger earthquakes. Ground shaking, liquefaction, landslides, tsunami and seiches are among the consequences of earthquakes, all of which have the potential to cause severe damage to lives, lifelines and infrastructure. Landslides are also common in the landscape surrounding the lakes. The majority of slopes surrounding the lakes are at significant risk from earthquake-induced failure under moderate to strong earthquake shaking. This level of shaking is expected to occur in any 50 year period around Lakes Lyndon and Coleridge, and in any 150 year period around Lake Tekapo. Injuries, fatalities and property damage can occur directly from landslide impact or from indirect effects such as flooding from landslide-generated tsunami or from landslide dam outbreaks. Lakes Lyndon, Coleridge and Tekapo are also susceptible to climate hazards, such as high winds, drought, heavy snowfall and heavy rainfall, which can lead to landslides and flooding. Future climate change due to global warming is most likely going to affect patterns of frequency and magnitudes of extreme weather events, leading to an increase in climate hazards. Before development is permitted around the lakes, it is essential that each of these hazards is considered so that unacceptably vulnerable areas can be avoided.
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Weisbrod, Barbara [Verfasser]. "Dynamics of toxic cyanobacteria in lakes and artificial water reservoirs / Barbara Weisbrod." Konstanz : KOPS Universität Konstanz, 2021. http://d-nb.info/1228271925/34.
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Lise, Johnsson. "Diffusion of CH4 and CO2 from subarctic lakes in Stordalen, Abisko." Thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-156579.
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West, Phillip D. "Use of Ponds and Lakes by Resident Canada Geese." W&M ScholarWorks, 2003. https://scholarworks.wm.edu/etd/1539626404.
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Kerisit, Arnaud. "Zooplankton Community Composition in Natural and Artificial Estuarine Passes of Lake Pontchartrain, Louisiana." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2527.
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I assessed the composition of zooplankton communities at the three tidal inlets connecting Lake Pontchartrain to Lake Borgne and subsequently to the Gulf of Mexico. The objectives of my research were to better understand the factors contributing to both spatial and temporal differences in zooplankton communities at the three locations. Monthly samplings of the neuston were conducted from September 2009 until April 2011 and then again from September 2012 until May 2013. Sampling consisted of triplicate tows using SeaGear “Bongo” nets. Water quality data along with water turbidity were recorded at each site and during each sampling effort. All specimens collected during the survey were quantified and identified to the lowest taxonomical unit. The results indicated that there were significant differences among the aquatic invertebrate communities composition among the three sites groups averaged across months (ANOSIM, R= 0.162, p = 0.001). The outcomes from this study could have strong implications for fisheries management and will provide a baseline for future research.
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Fernandez, Julianne M. "Carbon Dioxide and Methane in the North American Great Lakes." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504868932301161.
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Schmidt, Axel. "Radon as a natural geochemical tracer for study of groundwater discharge into lakes /." Leipzig : UFZ, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016691265&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Mailand, William A. "Comparison of Gastropod Assemblages from Natural and Phosphate Mine Lakes of Central Florida." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5830.
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Investigations were made examining the relationships between gastropod species richness and abundance across 20 phosphate and 20 natural lakes in Central Florida. In additional to lake category, age of phosphate lakes was used to determine if phosphate lakes ever approximate natural lakes. Additional physical, chemical, and biological parameters, including chlorophyll a, Ca, secchi, phosphorous, conductance, fish predation, and recreational lake use were investigated in order to determine if they affected gastropods with lake age. Comparisons were also made between gastropod species richness and average abundance and two groups of dominant vegetation categories: Panicum, a structurally complex macrophyte, and Typha, a less structurally complex macrophyte.
After phosphate mining operations are completed, Florida state regulations require the establishment of ecologically viable habitat (created lakes) which reflects the properties of regional natural lakes including vegetation structure, littoral zone, bank slope, and lake depth. The littoral zone is part of the mandated structure of the lake, and is of considerable importance to the uptake, storage, transformation and release of nutrients. Within the littoral zone, gastropods are a critical link in the food web with implications for the long term structure and function of a lake. They are known for their close associations with macrophytes and are common environmental indicators since they have limited mobility, high diversity, are well studied, are representative of their habitat type and have a widespread geographic range. They are also an important food sources for many predators in aquatic environments, include migratory waterfowl and game fish.
Gastropod species richness and abundance data were collected via standard net sweep methodology. Abundance was presented in catch per unit effort, therefore all abundance data were averages. Initial comparisons between gastropod species richness and average abundance yielded no significant differences between natural and phosphate lakes. However, when age was applied as a covariate, there was a significant difference between lake age as a continuous variable in species richness comparisons. Additionally, categorical comparisons between lakes older or younger than 30 years indicated significantly higher species richness and average abundance of gastropods in lakes phosphate lakes older than 30 years.
Physical and chemical properties of the lakes did not appear to influence gastropod populations between lakes of different ages. Fish predation interactions did not indicate any significant influence either. However, the presence of boat ramps did indicate a positive relationship between average gastropod abundance and species richness and recreational lake use.
Littoral zone macrophyte comparisons between dominant vegetation Typha and Panicum indicated a significantly positive relationship between gastropod species richness and average abundance in older phosphate lakes dominated by the more structurally complex Panicum macrophytes. Confidence in the Typha and Panicum results was confounded by lack of access to younger, Typha dominated, phosphate lakes. An increase in sample size for younger Typha lakes, with additional site access, may further support these findings.
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Meeuwig, Michael Hendrik. "Ecology of lacustrine-adfluvial bull trout populations in an interconnected system of natural lakes." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/meeuwig/MeeuwigM1208.pdf.
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Loss of connectivity among populations and interactions with nonnative species can negatively influence abundance of bull trout Salvelinus confluentus. Connectivity among bull trout populations and trophic relationships among native and nonnative fishes in Glacier National Park (GNP), Montana, were examined. Competition between juvenile (< or equal to 80 mm) bull trout and lake trout S. namaycush for cover habitat was examined in a laboratory environment. Connectivity among bull trout populations was inferred from genetic data. Barriers (i.e., waterfalls > or equal to 1.8 m) reduced genetic diversity and increased genetic differentiation among populations. Genetic differentiation was positively related to the length of tributary stream sections between populations and populations within the same drainage were more similar than populations in different drainages. Competition between bull trout and nonnative lake trout for prey is a potential mechanism for declines in bull trout abundance. Stable isotopes analyses were used to examine trophic relationships among fishes in GNP lakes. Bull trout and lake trout were top-level predators among lakes (Delta15N analysis), lake trout occupied a higher trophic position than bull trout (Delta15N analysis), and bull trout and lake trout likely used different foraging habitats (Delta13C analysis). These data do not support the prediction that these species are complete competitors for prey resources in GNP. Cover habitat protects fish from predators and is competed for if limiting. Habitat use by juvenile bull trout and lake trout was experimentally evaluated. Bull trout and lake trout differed in habitat use. Lake trout avoided bottom habitat, bull trout avoided water column habitat when lake trout were present, and neither species selected cover habitat. The hypothesis that bull trout and lake trout compete for cover habitat was not supported. The landscape in GNP allows connectivity among bull trout populations that are not isolated by barriers and one-way dispersal past waterfalls is likely. This connectivity allows dispersal and colonization by nonnative fishes into GNP lakes. Bull trout and nonnative lake trout are not complete competitors for prey resources in GNP or cover habitat; however, future studies should examine trophic shifts by these species associated with prey limitation and diel variability in habitat use by these species.
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Nicol, Jason. "Vegetation dynamics of the Menindee Lakes with reference to the seed bank." Title page, table of contents and summary only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phn633.pdf.
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O'Grady, Kevin Lawrence. "Facing natural hazards : uncertain and intertemporal elements of choosing shore protection along the Great Lakes /." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-165904/.
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Mostovaya, Alina. "Dissolved organic matter in lakes : Chemical diversity and continuum of reactivity." Doctoral thesis, Uppsala universitet, Limnologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-316893.
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Dissolved organic matter (DOM) is the largest pool of organic carbon in aquatic systems and an important component of the global carbon cycle. Large amounts of DOM are decomposed within lakes, resulting in fluxes of CO2 and CH4 to the atmosphere. Therefore, there is a considerable interest in understanding the controls of DOM decomposition in freshwaters. There is evidence that in lakes intrinsic controls related to DOM composition are of primary importance, yet our knowledge about molecular drivers of DOM degradation is limited. This thesis addresses the link between chemical composition and reactivity of lake DOM by applying an experimental approach, molecular-level DOM characterization, and kinetic modeling of DOM decay. The first study shows that photoinduced transformations and partial removal of colored aromatic components of DOM have profound effects on DOM degradation kinetics, mediated by the shifts in the relative share of rapidly and slowly degrading DOM fractions. Two following studies estimate exponential decay coefficients for each individual molecular formula identified within bulk DOM. A continuous distribution of exponential decay coefficients is found within bulk DOM, which directly corroborates the central and previously empirically untested assumption behind the reactivity continuum model of DOM decay. Further, individual decay rates are evaluated in connection to specific molecular properties. On average, highly unsaturated and phenolic compounds appear to be more persistent than compounds with higher aromatic content (plant polyphenols and polycondensed aromatics), and aliphatic compounds demonstrate the highest decay rates. The reactivity of aromatics additionally increases with increasing nominal oxidation state of carbon. Molecular analysis further indicates that increasing reactivity of DOM after UV exposure is caused by disintegration of supramolecular complexes. Study IV shows that changes in relative proportion of terrestrial versus algal DOM control degradability of DOM through seasons. Under ice, when algal-derived DOM is maximally depleted, DOM degradation potential converges to similarly low levels, regardless of lake type (productive or humic), and bacterial respiration primarily relies on terrestrial carbon. This suggests a general pattern of baseline metabolism across boreal lakes. I conclude that DOM is a dynamic reactivity continuum and a tight link exists between DOM behavior and compositional properties.
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Willis, Frank Levins. "A Multidisciplinary Approach for Determining the Extents of the Beds of Complex Natural Lakes in Louisiana." ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/988.
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In Louisiana, the beds of natural lakes are owned by the state. The locations of property boundary lines separating state property from private lands have usually been set by determining the levels of natural monuments known as ordinary high water marks. The term is confusing and subjective, leading to controversy in reference to its determination. Catahoula Lake in central Louisiana was chosen as a study site because of its large size, its 20-foot variation in water levels, and its low-relief perimeter. Geology, geomorphology, hydrology, archaeology, vegetation, dendrochronology and dendrohydrology of the ancient cypress fringe, nineteenth century land survey records, historical records, and time-series statistics were applied to determine the elevation range of ordinary high water. Research suggests that the level of the ordinary high water natural monument used universally in Louisiana to define lake boundaries is not the correct natural monument. This research suggests that, for example, the natural monument that defines the Catahoula Lake boundary is not a vertical monument, but rather an areal monument that was originally recognized by nineteenth century U.S. government surveyors and embedded in the evidence extracted from their original field notes. The solution coincides with the boundaries of regional land patents and offers a consistent solution to determining the boundaries of thousands of acres of disputed lands. The procedure is applicable to other lake and swamp boundaries in Louisiana and other states.
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Moon, Mike. "Hydroacoustic Substrate Classification Accuracy and Faunal Assemblage Variation Between Artificial and Natural Rock Regions: Bear Lake, Utah/Idaho." DigitalCommons@USU, 2007. https://digitalcommons.usu.edu/etd/7682.
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Research designed to elucidate artificial reef efficacy in attraction and production is lacking. Delineation of the rock reef habitat, coupled with faunal patterns of substrate use within artificial and natural reef regions, will allow elucidation of the potential of artificial reefs to attract sport fishes, and function as surrogate natural habitat for the conservation of endemic fish species. We compared faunal assemblages and habitat complexity between artificial and natural reefs to access the efficacy of artificial reefs in conservation of the native community, and attraction of sport fishes.
We used hydroacoustics to map artificial and natural rock reefs within Bear Lake. We compared the accuracy of Visual Bottom Typer (VBT, BioSonics, Seattle, WA) software to observed substrate in three regions of varying slope and rock complexity within Bear Lake. VBT demonstrated an ability to distinguish substrates regardless of rock complexity and slope, although inaccuracies were present. VBT biased classification towards predominant substrate in the survey regions.
We compared benthic invertebrate and fish catch in natural and artificial reef regions to assess the utility of artificial reefs in fisheries management. We assessed the potential of artificial reefs to function as foraging habitat for endemic fishes within Bear Lake. We compared benthic invertebrate taxa abundances and diversity between one region of artificial reefs, and two natural reefs in spring and summer. The artificial reefs hosted prey consumed by endemic Bonneville whitefish and Bear Lake sculpin. We assessed the potential of artificial reefs to function in attraction of sport fishes, and conservation of endemic fishes. We compared differences in fish catch per unit effort (CPUE) and diversity on rock and soft substrate between one artificial and two natural reef regions. Sport fishes attraction to the artificial reefs was minimal. Winter cisco and whitefish used the artificial reefs similarly to natural reefs. Fall lake trout, crayfish, and yellow perch used artificial and natural reefs dissimilarly.
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Bohlin, Veronica, and Nordqvist Anja Anderö. "Greenhouse gas emissions from three large lakes during the autumn 2020." Thesis, Linköpings universitet, Institutionen för tema, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-176275.
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Methane (CH4) and carbon dioxide (CO2) are two greenhouse gases and main drivers of global climate change. Lakes are known to be a source of CH4 and CO2 to the atmosphere. While the importance of these emissions is clear, their magnitudes and regulation are still uncertain due to the scarcity of flux measurement data from lakes. Most previous flux measurements have been carried out on lakes <10 km2 and the extrapolations are not representative of large lakes directly. Recent research has led to a growing recognition of the great importance of lakes as a source of emissions. Still, the relationship between environmental variables, lake properties and seasonal changes and the variability between and within lakes raises several question marks. Larger scale studies of greenhouse gases are needed to determine the spatial and temporal dynamics that exist. In this study, a floating chamber method and manual sampling was used to investigate the spatiotemporal variability and influencing variables of CH4 flux and concentration, as well as dissolved inorganic carbon (DIC) and pCO2aq (partial pressure of CO2 in the water). The sampling was conducted during five weeks in September and October 2020 in three large Swedish lakes. Our results generally showed varying CH4 values between the three lakes, indicating that nutrients affect the amount and emission of CH4. A pattern was found where the CH4 was higher near the shore and at a shallower depth. There was a correlation between CH4 concentration and the environmental variables wind speed and air- and water temperatures. Our DIC values were high in two of the lakes and low in one, all lakes’ DIC differed significantly from each other. The pCO2 did not have any difference within the lakes, and there was no difference between the lakes except in one case. Both DIC and pCO2 correlated with air- and water temperature. This study displays the large spatiotemporal variability within and between large lakes and that representative values for large lakes require more measurements under different conditions to distinguish how greenhouse gases emit and flux between lakes and atmosphere.Metan (CH4) och koldioxid (CO2) är två växthusgaser och stora drivkrafter för globala klimatförändringar. Sjöar är kända för att vara en källa för CH4 och CO2 till atmosfären. Trots att betydelsen av dessa utsläpp är tydlig är deras storlek och reglering fortfarande osäker på grund av brist på flödesmätdata från sjöar. De flesta tidigare flödesmätningarna har utförts på sjöar <10 km2 och det har påvisats att extrapoleringar inte är direkt representativa för stora sjöar. Ny forskning har lett till ett mer allmänt erkännande av sjöars stora betydelse som källa till utsläpp. Trots detta väcker förhållandet mellan miljövariabler, sjöegenskaper, säsongsförändringar och variationen mellan och inom sjöar flera frågetecken. Storskaliga studier om växthusgaser behövs för att bestämma den rumsliga och tidsmässiga dynamiken som finns. I denna studie användes en kammarmetod och manuell provtagning för att undersöka spatiotemporal variabilitet och miljövariabler som kan påverka CH4 flöde och koncentration, samt upplöst oorganiskt kol (DIC) och pCO2aq (partial trycket av CO2 i vattnet). Provtagningen genomfördes under fem veckor i september och oktober 2020 i tre stora svenska sjöar. Våra resultat visade generellt varierande CH4 värden mellan de tre sjöarna, vilket indikerade att näringsämnen påverkar mängd och utsläpp av CH4. Ett mönster noterades där CH4 var högre nära stranden och på ett grundare djup. Det fanns ett samband mellan CH4 koncentration och miljövariablerna vindhastighet och luft- och vattentemperatur. DIC-värdena var höga i två av sjöarna och låga i en, alla sjöarnas DIC skiljde sig signifikant från varandra. pCO2 hade ingen skillnad inom sjöarna, och det fanns ingen skillnad mellan sjöarna utom i ett fall. Både DIC och pCO2 korrelerade med luft- och vattentemperatur. Studien visar den stora spatiotemporala variationen inom och mellan stora sjöar och att representativa värden för stora sjöar kräver fler mätningar under olika förhållanden för att urskilja hur växthusgaser emitterar och flödar mellan sjöar och atmosfär.
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Dieras, Pauline L. "The persistence of oxbow lakes as aquatic habitats : an assessment of rates of change and patterns of alluviation." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/49392/.
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Oxbow lakes are of high ecological importance due to the number and the diversity of habitats they provide. They are created after the abandonment of meanders and subsequent sediment infilling leads to their progressive terrestrialisation, taking from a few months up to several centuries. Nonetheless, little is known about oxbow lake terrestrialisation processes, sediment composition, or why such a disparity exists in lakes’ longevity. To understand the controls on oxbow lakes alluviation, field observations, remotely sensed data and GIS analyses were combined. Sediment transfers in oxbow lakes were documented by topographic and sampling surveys of sites in France and Wales. Aerial photographs and maps were used to date cutoff events, analyse oxbow lakes geometry, and understand the controls on oxbow lake terrestrialisation for eight rivers of different characteristics. Findings from this study illustrate that the specific mechanism by which an oxbow lake is formed is critical to its persistence as a lake and to the sedimentary processes experienced. Chute cutoff oxbow lakes filled in 10 times faster than neck cutoffs and showed significantly different sediment deposits. Results also highlighted that oxbow lakes are not only fine-grained sediment stores, as often referred to, but can be significant bed material sinks since a site on the Ain River sequestered up to 34% of the bed material supply. However, the volume of sediment mobilised in the main channel during cutoff appeared to be larger than the bed-load stored in the former channel within the first decade after abandonment (40%). Sedimentary evidence showed that the terrestrialisation of oxbow lakes is driven by several processes: a flow separation zone at the entrance of the channel creating a sediment plug, sediment sorting by flow gradients and decantation in ponded areas. These results have important implications for the management of meandering rivers by providing a comprehensive analysis of depositional processes which also helps to predict oxbow lake longevity.
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Schaefer, Robert T. "Evaluating the Influences of Karst Hydrogeology on Freshwater Harmful Algal Blooms in Kentucky Lakes." TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1619.
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A problem exists in Nolin River Lake and Rough River Lake in Kentucky, due to the increasing prevalence of cyanobacterial-based harmful algal blooms (CyanoHABs) and the threats they pose to local communities. These lakes were developed as artificial reservoirs from embankment. Further complicating the issue, the lakes are located within a heavily karstified region and there exists no plan or method currently for monitoring or managing CyanoHABs in a karst region with regard to groundwater inputs to the lake systems or their tributaries. A mixture of techniques and analysis methods was used to determine the best way to monitor and possibly detect the formation and occurrence of CyanoHABs in artificial lakes that are located in karst landscapes. The methods focused on determining the effect groundwater has on CyanoHAB occurrence and formation, how much nutrient pollution is entering the system, from where the pollution is originating and, ultimately, how best to monitor and develop management practices against CyanoHAB occurrence. Techniques used included dual nitrate isotope tracing, collecting hydrogeochemical data, lake discharge data, historical CyanoHAB data, and biological tracer monitoring in both lakes. The lakes under study showed varying degrees of the influence karst plays in their seasonal changes from summer to winter pools. Lake water temperatures never dropped below the temperatures needed for one of the dominant cyanobacteria, Cylindrospermopsis raciborskii, to grow. Calculations of nutrient loadings indicated that over 3.5 x 106 kg of nitrate moved through Nolin River Lake during the course of the study. The presence and concentrations of E. coli when paired with weather and geochemical data also revealed karst groundwater pulses exerting an influence through the system in response to precipitation events. The nitrogen and oxygen isotope data indicate that a wide variety of nitrate pollution sources are entering the system and that a variety of management techniques must be deployed to combat this complex issue. A holistic approach that focuses on management and education about karst processes and CyanoHABs is suggested, with an emphasis on broader community involvement beyond just the populations living adjacent to the lakes.
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Straßer, Michael. "Quantifying Late Quaternary natural hazards in Swiss lakes subaquatic landslides, slope stability assessments, Paleoseismic reconstructions and lake outbursts." Zürich Schweizerische Geotechnische Kommission, 2008. http://e-collection.ethbib.ethz.ch/view/eth:30202?q=strasser.
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Gallant, Lauren Rachel. "Using Natural Archives to Reconstruct Environmental Changes Caused by Human Activities." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40386.
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The objective of this thesis was to develop new approaches and perspectives in resolving historical information from natural archives. Paleolimnology, the study of past aquatic environments using lake sediment cores, has greatly advanced our understanding of previous environments. This thesis intended to expand the range of historical information that may be used in paleolimnology and for historical reconstructions. Here I used pond sediments and a bat guano deposit as natural archives that recorded a history of events that I interpreted using a combination of chemical and biological measurements. In particular, I applied sterols and stanols as novel approaches for interpreting historical information in natural archives.
First, I examined the chemical and biological composition of lake sediments to track the human occupation of Dorset and Thule people in Canada’s High Arctic. As predicted, sterols, stanols, cadmium, copper, and zinc increased in sediments deposited during known periods of human occupation owing to nutrient addition, whereas these increases were absent in reference sites. These methods were further corroborated in a study of 20th century human occupation at Resolute Bay by examining similar constituents in waterbodies that received wastewater discharge.
Second, I used δ15N and δ13C to track the agricultural history of Jamaica using a 4,300-year-old bat guano deposit. I then used C/N, δ13C, and sterol and stanol ratios to detect two periods of increased frugivory relative to insectivory-based foraging. Metals normalized to titanium increased during the Industrial Revolution and 206Pb/207Pb values tracked the introduction and subsequent ban of leaded gasoline. I also examined the same chemical constituents in fresh bat guano from frugivorous, insectivorous, and sanguinivorous bats. C/N values decreased and cholestanol, cholesterol, and cholesterol/(cholesterol+sitosterol) values increased in bat guano according to trophic level.
This thesis demonstrated the strength of examining several independent lines of evidence to reconstruct historical activities in both High Arctic waterbody sediments and a bat guano deposit. I showed that human activities were traceable within natural archives over several thousand years thus demonstrating that the multi-proxy approach is a powerful tool that can conduct a broad range of analyses in various natural archives.
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Jonsson, Linus. "Evaluating the effects of climate change and interactions between salmonid populations in Swedish mountain lakes." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-173035.
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Previous studies suggest that global warming threatens populations of Arctic char (Salvelinus alpinus L.) and that interspecific competition from brown trout (Salmo trutta L.) can have negative effects when the species occur in sympatry. The aim of this study was to investigate if populations of Arctic char have declined in the last decades in lakes where they in the past have coexisted with brown trout. I examined this by revisiting five lakes previously sampled in the mountain region of Västerbotten (Sweden) during the 1960´s. This study repeated earlier sampling methods and examined the population size, biomasses and individual size and weight of all fish. Results showed increased abundances of brown trout and a trend towards declining Arctic char populations in the five lakes. Both Arctic char and brown trout currently had higher mean lengths than previous sampling years. This study also examined the diet and growth rate of both species. The diet analysis showed that the species to some extent overlapped in diet, while they also showed clear differences, where Arctic charr e.g. consumed more pelagic zooplankton. The growth rate was higher for Arctic char and differed between lakes. The shift towards more brown trout dominated lakes could depend on both that the two species are differently affected by a warmer climate, and that fishing habits have changed since the 1960´s. A warmer climate likely changed the species interaction in favor of trout and could lead to more competition and predation on Arctic char.
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Denton, John Curtis. "Current and Projected Nest Site Availability for Cavity-nesting Waterfowl in the Upper Mississippi River and Great Lakes Region." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/theses/536.
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Clearing of old growth forests resulted in a substantial loss of nesting habitat for cavity-nesting waterfowl during the late 19th and early 20th centuries. Since then, many hardwood forests have matured into size classes capable of producing cavities suitable for nesting ducks. To quantify changes in cavity availability in U. S. Fish and Wildlife Service Region 3, which contains most of the midwestern U.S., I examined current cavity availability at 4 sites where cavity availability had been estimated in the past; Mingo National Wildlife Refuge (NWR) in Missouri, Shiawassee NWR in Michigan, Mead Wildlife Area (WA) in Wisconsin, and Muscatatuck NWR in Indiana. I found densities of 1.8 ± 0.4, 1.4 ± 0.3, 0.9 ± 0.4, and 1.8 ± 0.4 suitable cavities per hectare at each of these sites, respectively. Suitable cavities per hectare increased at Mingo NWR (433%) since 1966 and Shiawassee NWR (1400%) since 1974, but remained similar at Mead WA and Muscatatuck NWR since the mid-1980's, after accounting for differences in past, study-specific criteria for cavity suitability. Differences among sites were likely due to variation in species composition, stage of forest maturation, timber management, and time elapsed since the previous studies. Comparison of size-class distributions for all trees and for trees with cavities indicated that cavities occur in the largest trees and that forests have yet to mature into the most prolific cavity-producing size classes. This conclusion was corroborated by forest growth modeling results from Forest Vegetation Simulator, a forest growth-modeling program from the USDA Forest Service. I used Forest Inventory and Analysis data to model growth from 2008 to 2058 at 10-year intervals for Region 3. Cavity per tree estimates from the 4 study sites were applied to modeling outputs, and cavity availability was projected to almost double over the entire region by 2058. Thus, the observed and further expected increases in cavity density in the region justify re-examination of nest box programs and possibly a reduction of artificial nest boxes in some areas of the region where sufficient natural cavities exist. Because current and future estimates indicate sufficient nest sites for cavity-nesting waterfowl, efforts should be spent protecting and restoring brood-rearing wetlands, which are known to be declining in many areas of Region 3.
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Warren, Jeffrey M. "Breeding Season Ecology and Demography of Lesser Scaup (Aythya affinis) at Red Rock Lakes National Wildlife Refuge." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/6928.
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It is hypothesized that individuals make reproductive decisions based on current assessments of their physiological condition and environmental conditions. For female lesser scaup (Aythya affinis), breeding occurs after an energetically costly spring migration. Increasing fat reserves (i.e., ‘body condition’) prior to breeding allows a female to produce a larger clutch of eggs, but time spent gaining body condition is costly in terms of time allowed to raise ducklings before freezing conditions in the fall. In Chapter 2 I explored rate of pre-breeding body condition gain in female lesser scaup, and how that rate influenced clutch size. Spring phenology, measured by proxy as water temperature, and water depth strongly influenced the rate at which females increased body condition. Early springs with low water levels led to greater rates of body condition gain in female scaup. The higher the rate of body condition gain, the larger the clutch of eggs females produced. Body condition is also an important determinant of breeding in female ducks; females in poor body condition are more likely to forego breeding. I explored how body condition, wetland conditions, and prior experience influence a female’s decision to breed in Chapter 3. Body condition was a strong determinant of when a female bred, with females in good body condition breeding earlier than females in poorer body condition. Habitat conditions were also important, with drought reducing the proportion of breeding lesser scaup females. In Chapter 4 I examined survival costs of reproduction in female scaup. Nesting exposes females to increased predation risk (a concurrent survival cost), and reduced post-breeding body condition may reduce female survival the subsequent non-breeding season (a serial, or ‘downstream’, survival cost). Female survival during breeding and non-breeding seasons was most correlated with breeding season water level on the study site, but in opposite directions. Breeding season survival increased with increasing water levels, while non-breeding season survival declined. High water levels on the study site increased the availability of presumably high-security nesting habitat, and also increased female reproductive effort. The former increased breeding season survival, while the latter reduced non-breeding season survival.
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Stevens, Greg. "Property rights in a Canadian mountain ecosystem, the changing world of natural resource decision-making in the Arrow Lakes, British Columbia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23511.pdf.
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Littlejohn, Carla Louise, and n/a. "Influence of Artificial Destratification on Limnological Processes in Lake Samsonvale (North Pine Dam), Queensland, Australia." Griffith University. Australian School of Environmental Studies, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050211.133123.
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Artificial destratification equipment was installed in Lake Samsonvale in October 1995 to reduce the biomass of potentially toxic cyanobacteria in the reservoir. This study was undertaken to investigate the effects of the destratifier on the limnological processes occurring in the lake and to determine if operation of the destratifier has been effective at reducing the summer populations of Cylindrospermopsis raciborskii and Microcystis aeruginosa. The study showed that artificial destratification of Lake Samsonvale has been successful at reducing the surface to bottom thermal gradient and increasing dissolved oxygen concentrations at depth. While the destratifier has not resulted in the lake becoming completely 'mixed' during summer, it has weakened resistance to mixing from meteorological events, which has led to a reduction in mean concentrations of total and dissolved phosphorus during summer. Although not conclusive, it is likely that the influence of the destratifier is restricted to a narrow radial distance around the bubbleplumes during periods of strong stability, so internal loading may continue to provide a substantial source of nutrients for cyanobacterial growth, particularly in regions of the lake less influenced by the destratifier. The results for cyanobacteria are less encouraging. Despite the reduction in concentrations of dissolved phosphorus, the destratifier has not been effective at reducing summer populations of C. raciborskii and M. aeruginosa. On the contrary, there is evidence to suggest that populations have actually increased which could have serious operational consequences for the lake by mixing the previously buoyant cyanobacteria to the level of the water off-take. The growth season for C. raciborskii has been extended by up to 3 months and population onset now occurs during spring. This increase in spring populations could be a result of significantly greater baseline populations during winter, or the earlier germination of akinetes as a result of increased sediment temperatures. The seasonal successional relationship between C. raciborskii and M. aeruginosa appears to have shifted from one of alternating dominance between the two species to one of co-existence under conditions of intermediate disturbance. It was concluded that although the continued operation of the destratifier may prove useful to minimise water treatment costs through reducing internal loading of dissolved constituents, it has not been successful in achieving its original objective of controlling cyanobacterial populations in the lake.
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Gomez, Giraldo Evelio Andres. "Observations of energy transfer mechanisms associated with internal waves." University of Western Australia. Centre for Water Research, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0045.
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[Truncated abstract] Internal waves redistribute energy and momentum in stratified lakes and constitute the path through which the energy that is introduced at the lake scale is cascaded down to the turbulent scales where mixing and dissipation take place. This research, based on intensive field data complemented with numerical simulations, covers several aspects of the energy flux path ranging from basin-scale waves with periods of several hours to high frequency waves with periods of few minutes. It was found that, at the basin-scale level, the horizontal shape of the lake at the level of the metalimnion controls the period and modal structure of the basin-scale natural modes, conforming to the dispersion relationship of internal waves in circular basins. The sloping bottom, in turn, produces local intensification of the wave motion due to focusing of internal wave rays over near-critical slopes, providing hot spots for the degeneration of the basin-scale waves due to shear instabilities, nonlinear processes and dissipation. Different types of high-frequency phenomena were observed in a stratified lake under different forcing conditions. The identification of the generation mechanisms revealed how these waves extract energy from the mean flow and the basin-scale waves. The changes to the stratification show that such waves contribute to mixing in different ways . . . Detailed field observations were used to develop a comprehensive description of an undocumented energy flux mechanism in which shear-instabilities with significant amplitudes away from the generation level are produced in the surface layer due to the shear generated by the wind. The vertical structure of these instabilities is such that the growing wave-related fluctuations strain the density field in the metalimnion triggering secondary instabilities. These instabilities also transport energy vertically to the thermocline where they transfer energy back to the mean flow through interaction with the background shear.
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Grimberg, Elis Mara. "Estudo comparativo da comunidade zooplanctônica de um sistema artificial (Represa de Barra Bonita, SP) e de um sistema natural (Lagoa Baixa Verde, MG)." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-07012016-122304/.
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A diversidade de organismos aquáticos de águas doces é ainda incompletamente conhecida no Brasil e atualmente graves problemas de alterações na qualidade das águas superficiais e destruição de habitats, têm levado a perdas de diversidade. O estudo da diversidade das comunidades planctônicas, incluindo uma análise ecológica dos fatores que alteram a riqueza e a abundância das espécies, é essencial para o entendimento dos processos controladores da diversidade. O presente trabalho visa analisar a diversidade da comunidade zooplanctônica em um reservatório e em um lago natural. As comunidades zooplantônicas da represa de Barra Bonita, SP e da lagoa Baixa Verde, MG, foram amostradas em diferentes periódicos, comparando-se a região limnética e a região litorânea. As principais variáveis físicas e químicas da água foram determinadas. As coletas de água foram feitas com garrafa de Van Dom e para as comunidades planctônicas com bomba de sucção, realizando-se coletas integradas na coluna d\'água e filtrando-se volumes de 100 a 200 litros, em redes de 20 e 68 micrômetros de abertura de malha para zooplâncton, respectivamente. As amostras foram fixadas com formol 4% e analisadas qualitativa e quantitativamente, utilizando-se bibliografias especializadas e recorrendo-se a especialistas para a identificação de algumas espécies. Com base em diferentes parâmetros físicos, químicos e biológicos, a represa de Barra Bonita pode ser considerada como um ambiente eutrófico e a lagoa Baixa Verde como um ambiente oligo-mesotrófico, corroborando classificações anteriormente realizadas por diversos autores. A comunidade zooplanctônica da represa de Barra Bonita foi bastante diversificada, sendo composta por 68 taxa, dos quais 31 taxa pertencentes aos Rotifera, 9 aos Cladocera e 8 aos Copepoda. Na lagoa Baixa Verde a riqueza de espécies foi baixa, tendo sido registrados 19 taxa, sendo 9 de Rotifera, 8 de Cladocera e 2 de Copepoda. A ocorrência das espécies Eurialona orientalis e Daphnia laevis na represa Barra Bonita constituem novos registros para aquele reservatório. Para a lagoa Baixa Verde, foram consideradas novas ocorrências de 8 espécies de Rotifera e 7 de Cladocera. A análise comparativa da diversidade e abundância do zooplâncton nas regiões limnéticas, revelou que no reservatório as maiores diversidades e densidades são encontradas na região limnética, ao passo que na lagoa a maior riqueza de espécies é encontrada na região litorânea, e a maior densidade na região limnética. As causas para estas diferenças são discutidas, em relação às características morfométricas, grau de trofia e a hipótese do distúrbio intermediário em reservatórios.The biodiversity of most Brazilian waters is not completely known. Nowadays there are great problems related to the changes in water quality and habitat destruction, leading to biodiversity losses. Studies focusing the diversity of planktonic communities including analyses on main ecological factors determining the richness of species and population numbers are very important to the understanding of biodiversity controlling processes. The present work aimed to analyze the diversity of zooplankton communities of an artificial system, a reservoir and of a natural one, a lake. Zooplankton sampling was carried out in Barra Bonita reservoir, SP, and in Baixa Verde lake MG, in contrasting hydrological periods, comparing stations located in tlile limnetic and in the littoral region of the lakes. Main physical and chemical variables were determined. Water was collected by a Van Dorn bottle and plankton communities were sampled from the whole water column by a suction pump under low pressure. One hundred liters of water were filtered through nets of 20 um and 68 um mesh sizes for phytoplankton and zooplankton respectively. Samples were preserved on 4% formol solution for posterior qualitative and quantitative analyses using specialized literature. Based on physical, chemical and biological characteristics Barra Bonita was considered an eutrophic environment and Baixa Verde an oligo-mesotrófico one, corroborating the findings of previous studies. The analysis of zooplankton composition at Barra Bonita revealed a diversified and rich community represented by 68 taxa, 31 taxa belonging to Rotifera, 9 to Cladocera and 8 Copepoda. On the other hand, in lake Baixa Verde species richness was low, comprising 19 taxa, from which 9 of Rotifera, 8 of Cladocera and 2 of Copepoda. The occurrence of the species Eurialona orientalis and Daphnia laevis in Barra Bonita reservoir constitutes new records of species for that environment and also for Baixa Verde Lake 8 species of Rotifera and 7 of Cladocera are new occurrences. The comparative analysis of the diversity and abundance of zooplankton in the limnetic and in the littoral region revealed that in Barra Bonita reservoir the highest species richness is found in the limnetic zone whereas in Lagoa Verde the highest richness is found in the littoral zone. The reasons for these difterences are discussed in relation to morphometry, trophic state and intermediate disturbance hypothesis.
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Stephens, Heather Marie. "Three Essays in Regional Economics." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338575844.
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Abra, Juliana [UNESP]. "Atributos populacionais e produtividade secundária de rotíferos em ambientes lacustres naturais e artificiais." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/106470.
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O presente estudo foi realizado em três lagoas marginais ao rio Paranapanema, em sua zona de desembocadura na Represa de Jurumirim, e em dez açudes em propriedades rurais na região noroeste paulista. O nosso objetivo principal foi avaliar a estrutura das comunidades de rotíferos e seus principais fatores determinantes de eventuais diferenças em ambientes sujeitos a perturbações e regimes hidrológicos distintos. As coletas foram realizadas em duas estações do ano (em estações seca de 2007 e 2008 e chuvosa de 2008 e 2009), na região litorânea e pelágica dos ambientes. Os seguintes parâmetros físicos e químicos foram analisados: profundidade, temperatura da água, transparência, pH, condutividade elétrica, oxigênio dissolvido, material em suspensão, clorofila a, nitrogênio e fósforo total. Foram analisados os atributos da comunidade de rotíferos: riqueza, diversidade, equitabilidade e abundância de espécies. As variáveis físicas e químicas da água apresentaram diferenças entre os locais e dentro dos ambientes (zona pelágica e litorânea), mas não foi possível elaborar padrões locais e temporais entre as diferenças dos fatores abióticos. As lagoas marginais apresentaram menores variações dos fatores físicos e químicos da água entre estações do ano. Maiores riquezas e diversidades significativas foram associadas à presença de macrófitas aquáticas e maiores abundâncias de espécies foram associadas à trofia dos ambientes. Não houve diferenças temporais significativas entre os atributos da comunidade dos rotíferos, mas houve diferenças entre os locais. Devido ao fato de incluir no estudo a região litorânea, houve uma grande contribuição em número de espécies que tem hábitos litorâneos e também novos registros de espécies para o estado de São Paulo foram feitos. A conectividade...
The present study was carried out at three lakes adjacent to the River Paranapanema in the region of its entrance into the Jurumirim Reservoir and at ten reservoirs on rural properties in the north west of the State of São Paulo. The aim was to evaluate rotifer community structure and the principal factors determining differences in environments subject to distinct perturbations and hydrological regimes. Samples were collected at two periods of the year (the dry seasons of 2007 and 2008 and the rainy seasons of 2008 and 2009) at the littoral and on the limnetic of the environments. The following physical and chemical parameters were determined: depth, water temperature, transparency, pH, electrical conductivity, dissolved oxygen, suspended matter, chlorophyll a, total nitrogen and phosphorus. The following characteristics of rotifer community structures were computed: species richness, diversity, uniformity and abundance. The physical and chemical variables of the water revealed differences between sites and within the two environments (limnetic and littoral zones), but no local and temporal patterns were identified in the differences between abiotic factors. The adjacent lakes presented the lowest seasonal variations with regard to the physical and chemical characteristics of the water. The highest species richness and diversity of species were related to the presence of aquatic macrophytes, and the greatest abundance of species was associated with the trophic conditions of environments. No significant temporal differences between the characteristics of the rotifer community structures were found, but differences between sites were recorded. Due to the fact that the study included the littoral zone, there was a significant contribution in terms of the number of species with littoral habitats, and some... (Complete abstract click electronic access below)
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Abra, Juliana. "Atributos populacionais e produtividade secundária de rotíferos em ambientes lacustres naturais e artificiais /." Botucatu, 2012. http://hdl.handle.net/11449/106470.
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Orientador: Raoul HenryCoorientador: Maria Stela Maioli Castilho Noli
Banca: Raoul Henry
Banca: Fábio Amodêo Lansac Tôha
Banca: Maria da Graça Gama Melão
Banca: Marcos Gomes Nogueira
Banca: Silvia Maria Caglierani Casanova
Resumo: O presente estudo foi realizado em três lagoas marginais ao rio Paranapanema, em sua zona de desembocadura na Represa de Jurumirim, e em dez açudes em propriedades rurais na região noroeste paulista. O nosso objetivo principal foi avaliar a estrutura das comunidades de rotíferos e seus principais fatores determinantes de eventuais diferenças em ambientes sujeitos a perturbações e regimes hidrológicos distintos. As coletas foram realizadas em duas estações do ano (em estações seca de 2007 e 2008 e chuvosa de 2008 e 2009), na região litorânea e pelágica dos ambientes. Os seguintes parâmetros físicos e químicos foram analisados: profundidade, temperatura da água, transparência, pH, condutividade elétrica, oxigênio dissolvido, material em suspensão, clorofila a, nitrogênio e fósforo total. Foram analisados os atributos da comunidade de rotíferos: riqueza, diversidade, equitabilidade e abundância de espécies. As variáveis físicas e químicas da água apresentaram diferenças entre os locais e dentro dos ambientes (zona pelágica e litorânea), mas não foi possível elaborar padrões locais e temporais entre as diferenças dos fatores abióticos. As lagoas marginais apresentaram menores variações dos fatores físicos e químicos da água entre estações do ano. Maiores riquezas e diversidades significativas foram associadas à presença de macrófitas aquáticas e maiores abundâncias de espécies foram associadas à trofia dos ambientes. Não houve diferenças temporais significativas entre os atributos da comunidade dos rotíferos, mas houve diferenças entre os locais. Devido ao fato de incluir no estudo a região litorânea, houve uma grande contribuição em número de espécies que tem hábitos litorâneos e também novos registros de espécies para o estado de São Paulo foram feitos. A conectividade... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The present study was carried out at three lakes adjacent to the River Paranapanema in the region of its entrance into the Jurumirim Reservoir and at ten reservoirs on rural properties in the north west of the State of São Paulo. The aim was to evaluate rotifer community structure and the principal factors determining differences in environments subject to distinct perturbations and hydrological regimes. Samples were collected at two periods of the year (the dry seasons of 2007 and 2008 and the rainy seasons of 2008 and 2009) at the littoral and on the limnetic of the environments. The following physical and chemical parameters were determined: depth, water temperature, transparency, pH, electrical conductivity, dissolved oxygen, suspended matter, chlorophyll a, total nitrogen and phosphorus. The following characteristics of rotifer community structures were computed: species richness, diversity, uniformity and abundance. The physical and chemical variables of the water revealed differences between sites and within the two environments (limnetic and littoral zones), but no local and temporal patterns were identified in the differences between abiotic factors. The adjacent lakes presented the lowest seasonal variations with regard to the physical and chemical characteristics of the water. The highest species richness and diversity of species were related to the presence of aquatic macrophytes, and the greatest abundance of species was associated with the trophic conditions of environments. No significant temporal differences between the characteristics of the rotifer community structures were found, but differences between sites were recorded. Due to the fact that the study included the littoral zone, there was a significant contribution in terms of the number of species with littoral habitats, and some... (Complete abstract click electronic access below)
Doutor
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Adams, Jennifer Karen. "Multiproxy reconstructions of recent environmental change : understanding the ecological response of shallow lakes within the Selenga River basin, southeast Siberia, to anthropogenic and natural disturbances." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10040922/.
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Floodplain delta wetlands are highly productive and critical ecosystems between terrestrial uplands and large, aquatic systems. The largest inland freshwater floodplain delta in the world is the Selenga Delta. The Selenga Delta serves a crucial function between UNESCO World Heritage Site Lake Baikal, and the lake’s primary inflow, the Selenga River, and its tributaries. The Selenga River flows approximately 950 km through northern Mongolia and southern Siberia prior to reaching the Selenga Delta, and within the Selenga River basin, numerous anthropogenic activities, including industry, urban settlements, agriculture, and mining, have the potential to cause ecological damage to the Selenga River and its tributaries. The aims of this thesis were to assess the extent of current and historical contamination in Selenga River basin shallow lakes, investigate the primary environmental drivers of variability in ecological structure and function of shallow lakes within the basin, and understand the ecological responses and sensitivity to disturbance. Multiproxy palaeolimnological investigstions of three shallow lakes with the Selenga River basin (two from within the Selenga Delta and one from a more heavily industrialized region), were chosen to undertake a multiproxy palaeolimnological approach to addressing these aims. Investigations on shallow lakes across the Selenga Delta revealed that variability and composition of contemporary ecological communities are determined by degree of connectivity, trophic interactions, and physical landscape parameters such as lake surface area and depth. The greatest period of contamination of shallow lakes (by trace metals and persistent organic pollutants) occurred in the mid-20th century, closely linked with periods of economic development in Russia. However the main drivers of ecological variability since the 19th century have been natural and anthropogenically-induced changes in hydrological regimes, and nutrient pollution, which resulted in significant ecological shifts across multiple trophic levels in shallow lakes.
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Velissariou, Vasilia. "Examination of the Barotropic Behavior of the Princeton Coastal Ocean Model in Lake Erie, Using Water Elevations From Gage Stations and Topex/Poseidon Altimeters." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1252401353.
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Sandberg, Linda. "Movement of the Eurasian perch (Perca fluviatilis) : Individual responses to abiotic factors." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-172751.
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Movement increases the probability for an individual to find food resources, but also increase the metabolic costs and exposure to predators. Hence, swimming behavior of fish is strongly coupled to fitness. Even though swimming activity has been studied in numerous laboratory settings, less is known about in situ activity and its dependence on abiotic factors (temperature, light conditions and barometric pressure). In this study I hypothesized that the activity increases with 1) increasing temperature and decrease with 2) barometric pressure variability and 3) average light conditions (h/day). In order to test the universality of the three hypotheses I also searched for size dependent effects. Fish activity (km/day) was measured in three lakes on individual fish (N=14-21 per lake) using acoustic telemetry providing tracking of fish at a time resolution from seconds to hours. A positive correlation between temperature and swimming activity in line with my first hypothesis was only observed in one of the lakes. The activity decreased with increased variability in barometric pressure in two of the lakes, a finding supporting my second hypothesis. Meanwhile increased light conditions (h/day) decreased activity in one of the lakes, as predicted by my third hypothesis. Nevertheless, none of my hypotheses were valid in all three of the lakes and perch reacted differently to the abiotic factors. One of the possible explanations for this is the importance of size differences as I noticed that the swimming activity differed between bigger and smaller individuals. My findings suggest that not only the temperature, barometric pressure and light conditions alone predict the activity in perch, but also the fish individual size, predation and the metabolic costs linked to thermoregulation.
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Agars, Robert C. "Assessment of the potential environmental effects of soluble hydraulic oil on natural waters /." [Richmond, N.S.W.] : Centre for Electrochemical Research and Analytical Technology, School of Science, Food and Horticulture, University of Western Sydney, 2001. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030409.114931/index.html.
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Thesis (M.Sc. (Hons))--University of Western Sydney, 2001."A thesis presented for the Degree of Master of Science (Honours), Centre for Electrochemical Research and Analytical Technology, School of Science, Food and Horticulture, University of Western Sydney, March 2001." Bibliography: leaves 62-67.
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Simonson, Martin Albert. "Modeling Nearshore Fish Community Responses to Shoreline Types in Lake Erie." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1501861205611006.
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Kozel, Carrie L. "Early Feeding In Lake Trout Fry (salvelinus Namaycush) As A Mechanism For Ameliorating Thiamine Deficiency Complex." ScholarWorks @ UVM, 2017. http://scholarworks.uvm.edu/graddis/685.
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Recruitment failure of lake trout (Salvelinus namaycush) in the Great Lakes has been attributed in part to the consumption of alewife (Alosa pseudoharengus) by adult lake trout, leading to Thiamine Deficiency Complex (TDC) and early mortality in fry. The current understanding of thiamine deficiency in lake trout fry is based on information from culture and hatchery settings, which do not represent conditions fry experience in the wild and may influence the occurrence of TDC. In the wild, lake trout fry have access to zooplankton immediately following hatching; previous studies found that wild fry begin feeding before complete yolk-sac absorption. However, hatchery-raised fry are not provided with food until after yolk-sac absorption, long after the development of TDC. Zooplankton are a potential source of dietary thiamine for wild fry in the early life stages that has not previously been considered in the occurrence of thiamine deficiency. We postulated that wild-hatched fry could mitigate thiamine deficiency through early feeding on natural prey. Specifically, we hypothesized 1) feeding should increase thiamine concentrations relative to unfed fry and 2) feeding should increase survival relative to unfed fry. Feeding experiments were conducted on lake trout fry reared from eggs collected from Lake Champlain in 2014 and Cayuga Lake in 2015. A fully crossed experimental design was used to determine the effect of early feeding by lake trout fry in thiamine replete and thiamine deplete treatments before and after feeding. Overall, thiamine concentrations and survival did not significantly differ between fed and unfed fry. Thiamine concentrations increased from egg stage to hatching in both years, suggesting a potential source of thiamine, which had not previously been considered, was available to the lake trout eggs during development.
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Makopoulou, Eirini. "Periglacial and glacial landform mapping in the Las Veguitas catchment, Cordillera Frondal of the Andes (Argentina)." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-160931.
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The semi-arid and arid Andes of South America are characterized by large areas with glacial and periglacial environments. This study focusses on the distribution of glacial and periglacial landforms in the Las Veguitas catchment, Cordillera Frontal, Argentina. A detailed geomorphological map of the Las Veguitas catchment is presented, based on high-resolution elevation data (ALOSPALSAR), satellite imagery (Landsat 8, World View 2, Google Earth), and field studies. First, a general topographical analysis is performed for the entire Las Veguitas catchment, including elevation, slope and aspect characteristics. Second, the altitudinal range of glacial features (glaciers, debris covered glaciers and thermokarst ponds on glaciers) and the altitudinal range and predominant aspect of periglacial features (active, inactive and fossil rock glaciers) are analyzed. Currently, glaciers are restricted to ≥ 4300m, but moraines are identified to elevations of c. 3200m. Active rock glaciers extend down to c. 3450m and have a more southern aspect then both inactive and fossil rock glaciers. Third, a temporal analysis has been performed of glacier and rock glacier flow using a time series of remote sensing images. Glacier flow traced by the displacement of thermokarst lake features (2006-2016) had a mean velocity of 6.66m/yr. The mean velocity of rock glaciers (1963-2017) was much lower at 0.63m/yr. Finally, the thesis discusses limitations and uncertainties in study methods and suggestions for further research activities.
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Suurkuukka, H. (Heli). "Spatial and temporal variability of freshwater biodiversity in natural and modified forested landscapes." Doctoral thesis, Oulun yliopisto, 2014. http://urn.fi/urn:isbn:9789526207087.
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Abstract Understanding of natural and human induced changes to freshwater biodiversity patterns is critical for efficiently conserving and managing these highly impacted ecosystems. In this doctoral thesis, I study the natural spatial and temporal variability of littoral macroinvertebrate communities, as well as aquatic biodiversity responses (of bryophytes, macroinvertebrates and diatoms) to human impact on forested headwater streams. I also study the temporal variability of natural and human-impacted stream communities. I show that littoral macroinvertebrate communities are most variable between individual samples and to some extent between littorals, and that the diversity patterns of rare and common littoral macroinvertebrates vary at different spatial scales. Temporal (interannual) variability is of minor importance, particularly for the core species of the community. For rare species, however, the temporal component was generally more important than spatial turnover. For headwater streams, I show that most taxonomic groups responded negatively to human impact on the adjacent riparian forest. Nevertheless, pristine riparian forest is not a sufficient surrogate for stream biodiversity as also streams with relatively disturbed riparian forests supported diverse benthic communities. A rapid classification method based on the physical structure of the stream channel and its riparian forest is able to identify the reference-state communities, as well as the most severely altered communities, but a reliable identification of the intermediately-disturbed sites would need more precise information about the key stressors of stream communities. I found that fine sediments originating from forest drainage were the main factor causing reduction of stream biodiversity. I also found that forestry impacted streams varied temporally more than pristine streams, emphasizing the importance of interannual sampling of impacted streams for a reliable status assessmentTiivistelmä Luonnollisen ja ihmisen aiheuttaman biodiversiteettivaihtelun ymmärtäminen hoito- ja suojelutoimissa on tärkeää pienvesien monimuotoisuuden turvaamiseksi. Tarkastelen väitöskirjassani järvien rantavyöhykkeen pohjaeläinten ajallista ja paikallista vaihtelua sekä latvapurojen eliöyhteisöjen (pohjaeläimet, sammalet, piilevät) vasteita ihmisen aiheuttamaan fysikaaliseen muutokseen rantametsässä ja purouomassa. Tarkastelen myös ajallisen vaihtelun eroja luonnontilaisten ja ihmisvaikutteisten latvapurojen eliöyhteisöjen välillä. Osoitan, että järven rantavyöhykkeen pohjaeläinyhteisöt vaihtelevat eniten yksittäisten näytteiden välillä ja pienessä määrin eri rantojen välillä, mutta ajallinen vaihtelu ei heikennä tulosten luotettavuutta muiden kuin harvinaisten lajien osalta yhteen vuoteen rajoittuvassa näytteenotossa. Purotutkimuksissa osoitan, että useiden vesieliöryhmien lajirunsaus muuttuu ihmisen aiheuttaman rantametsän muutoksen seurauksena, mutta luonnontilaista rantametsää ei silti voida pitää yksiselitteisesti myös puron suojelutason mittarina, koska se ei välttämättä turvaa eliöiden lajistollista eheyttä suhteessa alkuperäiseen alueelliseen lajistoon. Rantametsän ja uoman fysikaalisiin rakennepiirteisiin perustuvaa nopeaa luokittelumenetelmää voidaan käyttää eliöyhteisöltään monimuotoisimpien ja metsätalouden voimakkaimmin rasittamien purojen tunnistamisessa. Eliöyhteisöltään lievemmin muutettujen purojen luotettavaan erotteluun luokittelun pitäisi kuitenkin sisältää tarkempaa tietoa metsäojitusten aiheuttamasta liettymisestä, joka on tulosteni perusteella haitallisin metsätaloudesta johtuva puroyhteisöjä rasittava tekijä. Havaitsin myös metsätalouden rasittamien purojen tilanarvioinnin toistettavuuden olevan luonnontilaisia puroja heikompaa, joten metsätalouden rasittamien purojen pidempiaikainen seuraaminen tuntuu välttämättömältä luotettavien tilanarvioiden tuottamiseksi
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Keith, Hamish D. "Disaster management and response : a lifelines study for the Queenstown Lakes District : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Hazard and Disaster Management in the University of Canterbury /." Thesis, University of Canterbury. Department of Geological Sciences, 2008. http://hdl.handle.net/10092/2563.
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The Queenstown Lakes District is vulnerable to a number of natural hazards. These include earthquakes, mass movements, meteorological hazards and flooding. Many of the hazards that threaten the district have the potential to cause loss of life or injury and all of them have the potential to cause severe damage to homes, businesses and other infrastructure. Infrastructure and services that support life and business in the community, and that are used everyday are known as lifelines. Lifelines are generally taken for granted but are directly associated with the quality of life that we live. Lifelines include electricity, telecommunication, water supply, wastewater removal, transportation and emergency services. Following a major disaster the need for safe, effective and timely restoration of these lifeline systems is critical. This project analyses the vulnerability of lifelines with respect to natural hazards with the aim that it can be used to ensure that when a disaster occurs appropriate and efficient action is taken to minimise the impact. This thesis also attempts to raise awareness and understanding of the hazards that threaten the Queenstown Lakes District as well as emphasise the importance of lifelines and what's involved in their management. This will hopefully help readers understand the likely impacts of a disaster so that when one occurs they will not be completely caught unaware. This thesis will also hopefully entice the reader to better prepare for a disaster. Scenarios of each hazard were created based upon current scientific understanding and are used to illustrate more clearly the priorities that need to be addressed during the response and recovery phases of a disaster.
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Banda, Jo Ann. "Temporal and Spatial Genetic Consistency of Walleye (Sander vitreus) Spawning Groups." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1321498533.
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Souza, Marcos Barros de. "Influência de lagos artificiais no clima local e no clima urbano: estudo de caso em Presidente Epitácio (SP)." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-08112010-162614/.
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Nas últimas décadas tem sido temática de estudos as alterações realizadas no meio ambiente urbano e as variabilidades climáticas que ocorrem a partir das intervenções, principalmente no que se refere à formação de lagos artificiais para construção de usinas hidrelétricas. As transformações antrópicas de um determinado espaço físico podem ocasionar variações nos atributos climáticos, como a umidade relativa do ar e a temperatura do ar, dentre outros. O objetivo geral desta pesquisa foi verificar as possíveis alterações no clima local e do clima urbano da cidade de Presidente Epitácio, localizada no extremo oeste do Estado de São Paulo, devido à formação do lago artificial para a construção da Usina Hidrelétrica Engenheiro Sérgio Motta (Porto Primavera), utilizando registros da temperatura do ar e da umidade relativa do ar em um transecto da margem do lago passando pela área urbana até o ambiente rural circunvizinho, analisando as variáveis temporal, espacial e horária em diferentes períodos do ano (primavera, verão, outono e inverno), bem como a análise dos desvios da temperatura do ar e da umidade relativa do ar, entre os postos localizados próximos ao lago, na área intra-urbana e na área rural. A área de estudo constitui o município de Presidente Epitácio (SP) e o lago artificial foi formado pelo represamento das áreas do rio Paraná, na divisa entre os Estados de São Paulo e de Mato Grosso do Sul. A região possui clima tropical com verão úmido e inverno seco, registrando temperaturas máximas de 40°C e mínimas de 10°C, tendo os meses chuvosos de novembro a março com pluviosidade média anual de 1.200mm a 1.400mm e umidade relativa do ar de cerca de 80%. Para a coleta de dados realizada entre setembro de 2008 e setembro de 2009, sendo trinta dias em cada estação (primavera, verão, outono e inverno), foram utilizados sensores digitais de temperatura do ar e de umidade relativa do ar da marca StowAway, instalados em sete postos. Na variação da temperatura do ar entre os postos da área intra-urbana, da área de influência do lago e da área rural foi possível verificar que nos horários de maior produção de energia, ou seja, durante o período diurno as diferenças das amplitudes diminuem e no período noturno aumentam, devido ao volume de energia produzida no período diurno e dissipação desta energia no período noturno. Na variação da umidade relativa do ar entre os postos da área intra-urbana, da área de influência do lago e da área rural verificou-se que as amplitudes são maiores durante o período noturno, sendo menores durante o período diurno, ou seja, as amplitudes higrométricas são menores na área de influência do lago e na área rural do que na área intra-urbana. Conclui-se que, apesar de não haver valores significativos entre os postos, a presença do lago não contribui para o aumento da temperatura do ar e da umidade relativa do ar, porém funciona como um maior equilíbrio térmico e higrométrico.In the last decades it has been subject of studies the changes urban environment and the climate variability that occur from interventions, especially as regards the formation of artificial lakes for hydroelectric plants. The anthropogenic transformation of a given physical space can cause variations in climatic attributes such as relative humidity and air temperature, among others. The objective of this research was to investigate the possible changes in local weather and climate in the city of Presidente Epitácio, located in the extreme west of São Paulo, due to the formation of an artificial lake to build the hydroelectric plant Engenheiro Sérgio Motta (Porto Primavera), using records of air temperature and relative humidity in a transect from the shore through the urban area to the surrounding rural environment, analyzing the temporal, spatial and hourly variables at different times of year (spring, summer, autumn and winter), as well as analysis of the deviations of air temperature and relative humidity between stations located near the lake in the intra-urban and rural areas. The study area is the city of Presidente Epitácio (SP) and the artificial lake was formed by damming the areas of the Paraná river on the border between the states of São Paulo and Mato Grosso do Sul. The region has tropical climate with wet summer and dry winter, recording maximum temperatures of 40°C and minimum 10°C in the rainy months from November to March with average annual rainfall of 1,200mm to 1,400mm and relative humidity of about 80%. For data collection conducted between September 2008 and September 2009, with thirty days in each season (spring, summer, autumn and winter), digital sensors for air temperature and relative humidity of the StowAway brand were used and installed in seven stations. The variation of air temperature between the positions of intra-urban area, of near de lake area and of the rural area it was verified that at times of increased energy production. During daytime differences of amplitudes decrease and increase at night due to the volume of energy produced during the day and dissipation of energy at night. Regarding the variation of relative humidity between the positions of intra-urban area, of near the lake and the rural area it was found that the amplitudes are larger during the night, being low during daytime. The the amplitudes are smaller hygrometric in the influence area of the lake and the rural area than in intra-urban area. We conclude that, although no significant values among the sites, the presence of the lake does not contribute to the increase of air temperature and relative humidity, but contributes to a better thermal and hygrometric balance.
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Planella, Morató Jesús. "Intermittency of turbulence in natural waters: patchiness in the thermocline of a lake under low winds and small-scale intermittency in the bottom boundary layer of a tidal flow." Doctoral thesis, Universitat de Girona, 2015. http://hdl.handle.net/10803/320432.
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Turbulence intermittency influences so many processes in natural waters on a wide range of scales. This work analyzes intermittency, both internal and external, by considering two cases: the thermocline of a small lake under low winds and the bottom boundary layer of a tidal flow.
External intermittency in Lake Banyoles is studied based on patches. Variability of their sizes and turbulent scales is described using probability models, which are consistent with marine turbulence results. Dynamics of mixing depends on the phase of the dominant internal seiche. Episodic and powerful wind gusts generate large patches in the lake's interior.
Internal intermittency is analyzed based the analysis of tidal flow data. Scaling exponents of structure functions and moments of the dissipation rate fit to multifractal model. For energetic episodes intermittency parameters approach the values expected for fully developed turbulence. They increase with decreasing of Reynolds numbers, which is associated with underdeveloped turbulence.El comportament intermitent de la turbulència afecta molts processos en els sistemes aquàtics. Aquest treball estudia la intermitència interna i externa en dos casos particulars: la termoclina d'un estany sota vents fluixos i la capa de fons d'un corrent de marea. La intermitència externa a l'estany de Banyoles s'analitza estudiant la variabilitat de mides i escales turbulentes dels claps, que s'ajusten bé als models de probabilitat obtinguts també en turbulència marina. La dinàmica de barreja depèn de la fase de la seca interna dominant a l'estany. Els claps grans generats a l'interior s'han relacionat amb cops de vent episòdics forts. La intermitència interna s'analitza en un corrent de marea (funcions d'estructura i moments de la dissipació). Els exponents d'escalatge s'ajusten a models multifractals, amb paràmetres propers als de turbulència completament desenvolupada per a episodis energètics. Aquests augmenten quan el nombre de Reynolds disminueix, possiblement degut a turbulència no completament desenvolupada.
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Almeida, Caio Augusto de. "Aspectos do ciclo de vida de espécies bentônicas nativas e sua utilização na avaliação da qualidade de sedimentos de lagos naturais e reservatórios." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-29082007-210238/.
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Os estudos ecológicos, com vistas para a conservação do meio ambiente, vêm sendo intensificados desde meados do século XX. Devido à integração com várias outras ciências durante o processo de formação do conhecimento ecológico, esses estudos têm se tornado essenciais para o desenvolvimento de tecnologias e de políticas adequadas ao gerenciamento dos recursos naturais, em especial dos recursos hídricos. Estudos que contemplem a comparação entre sistemas naturais e artificiais são importantes na medida em que permitem investigar como esses sistemas reagem a perturbações antropogênicas de curto ou longo prazo. Há um consenso geral de que a camada de sedimento dos corpos d\'água desempenha um papel fundamental na dinâmica de transporte, acumulação e disponibilização de contaminantes nesses sistemas. A tríade de qualidade de sedimento é considerada uma das melhores abordagens para o estudo de sistemas aquáticos impactados por efluentes oriundos de atividades antrópicas. Habitats dulcícolas são particularmente suscetíveis à introdução de espécies exóticas de invertebrados. Uma possível rota de introdução dessas espécies é o cultivo em laboratório para testes de toxicidade. Substituí-las por espécies nativas com sensibilidade similar pode prevenir a introdução acidental de espécies exóticas, além de facilitar a obtenção de inóculos para as renovações da cultura, e de serem mais significativos na extrapolação dos resultados laboratoriais para situações em campo. Duas espécies nativas de organismos bentônicos foram estudadas com relação à aspectos de suas biologia e a adequação como organismos-teste em ensaios ecotoxicológicos: Chironomus xanthus (Díptera) e Branchiura sowerbyi (Oligochaeta). Os resultados dos testes de toxicidade ao pentaclorofenol para C. xanthus permitiram calcular uma CL50 (96h) de 0,111 mg/L com uma faixa de sensibilidade entre 0,082 e 0,141 mg/L. Os testes de sensibilidade de B. sowerbyi ao cloreto de potássio resultaram em uma CL50 (96h) de 0,364 g/L com uma faixa de sensibilidade entre 0,177 e 0,551 g/L. Realizou-se também um balanço energético geracional cumulativo para C. xanthus, obtendo-se os seguintes valores para as eficiências metabólicas calculadas: coeficiente instantâneo de assimilação de 98,14%, coeficiente de produção bruta de 14,76% e coeficiente de produção líquida de 15,03%. Além dos ensaios toxicológicos com os dois organismos, realizou-se um estudo comparativo entre o sistema de reservatórios em cascata do rio Tietê com o sistema de lagos naturais do Vale do Rio Doce, aplicando-se os princípios da tríade de qualidade de sedimentos. Os resultados dessa análise permitiram classificar os reservatórios estudados de acordo com o nível de qualidade ambiental sendo que o reservatório de Barra Bonita (SP) é considerado como o de pior qualidade, enquanto que os lagos do Vale do Rio Doce (MG) encontram-se ainda relativamente preservados.The ecological studies, with views for the conservation of the environment, have been intensified from middles of the century XX. Due to the integration with several other sciences during the process of ecological knowledge formation, those studies have become essential to the development of technologies and appropriate politics for the administration of the natural resource. Studies that contemplate the comparison among natural and artificial systems are important in the way it is allowed to investigate as those systems react to antropogenic disturbances of short or long periods. There is a general consensus that the sediment of the water bodies plays a fundamental part in the transport dynamics, accumulation and disposal of pollutants in these systems. The triad of sediment quality is considered one of the best approaches for the study the influence of pollutants originated from of human activities in aquatic ecossystems. Freshwater habitats are particularly susceptible to the introduction of exotic species of invertebrates. A possible route of introduction of those species is the cultivation in laboratory for toxicity tests. To substitute them for native species with similar sensibility can prevent the accidental introduction of exotic species, besides facilitating the inocula obtaining for the renewals of the culture, and may be more significant in the extrapolation of the laboratories results for field situations. Two native species of benthic organisms were studied regarding to aspects of their biology and the adaptation as organism-test in ecotoxicological assays: Chironomus xanthus (Díptera) and Branchiura sowerbyi (Oligochaeta). The results of the toxicity tests to the pcp for C. xanthus allowed to calculate a LC50 (96h) of 0,111 mg/L with a sensitivity range of 0,082 - 0,141 mg/L. The sensitivity testes for B. sowerbyi to the KCl resulted in a LC50 (96h) of 0,364 g/L with a sensitivity range of 0,177 - 0,551 g/L. An energy budget of C. xanthus was performed, being obtained the following values for the calculated metabolic efficiencies: instantaneous coefficient of assimilation of 98,14%, coefficient of production of 14,76% and coefficient of liquid production of 15,03%. A comparative study among the system of reservoirs in cascade of the Tietê river with the system of natural lakes of Rio Doce valley was applied following the principles of the triad of quality of sediments. The results of that analyze allowed to classify the reservoirs studied in agreement with the level of environmental quality and the reservoir of Barra Bonita (SP) is considered as the one of worse quality, while the lakes of Rio Doce Valley (MG) still meet relatively preserved.
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Švec, Martin. "Revitalizace hotelového zařízení, Přehrada Brno." Master's thesis, Vysoké učení technické v Brně. Fakulta architektury, 2014. http://www.nusl.cz/ntk/nusl-216102.
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This is the proposal of the new utilization of the former recreational centre, which is situated in the beautiful surrounding of the Brno lake. It has been abandoned for many years and is suffering from decay. It has been built in the 1970's for the demand of the Socialistic youth union (remark: the youth organisation of the communist's party). There were held international political conventions and educational sojourns for the students of high schools and universities. The new utilization will be analogous. Only the communist's ideals will be replaced with the ideals of today's democratical society – especially friendly relations between mankind and environment. There will be created the environmental educational centre with the meeting spaces, conference hall and accomodation. The universal concept enables the usage of the facility also for the international students' workshops, training courses, teambuilding events etc. The ecological educational centre primarily makes the good example and is the live educational requisite. Thanks to the concept of the original facility is very convenient the refurbishment to the standard of the energetically passive building, which consists from the natural materials and utilizes renewable energy resources. Because of the very poor technical condition and devastation of the building will be re-used only basement and steel framework. This solution is more economical than the demolition and following new construction. The construction core of the building is almost for free. However, only if we make minimal changes in the framework and we preserve the original building's shape. On the steel framework will be created the new lightweight housing, which will be made from wood, straw pannels and filled with the cannabis thermal insulation. Almost all the roofs will be covered with the photovoltaic foils and the heat source will be air heat pump. The area is very pleasant place to stay. It's full of sunshine all day long and offers very beautiful view of the lake. The main building and bungalows profit of the attractive views. All the former recreational area has was designed to make the people meeting together and to provide the freedom of move and wide variety of activities. However, the rooms and bungalows provide the highest privacy. The inside and outside of the buildings are shading into each other. All the recreational ground – in exterior and interior – is full of liveliness, in the opposite of the rooms, which are the private islands. This aspect, which is present in the former concept from the 1970's, is to be preserved. The former hotel building is distinguished by the quality architectural concept, above-average in the age of origin. It is thanks to the dynamically balanced composition – inspirative today too, and visually interesting interior design of the meeting spaces. This proposal attempts to continue in this qualities. The ground is enriched with the relaxational spaces and the outside gym path. In the opposite of the original state the area is open to the public and is utilized as a park for leisure activities.
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Ferreira, Diogo Tavares Antão Folhas. "Sampling and structural characterization of natural organic matter of thermokarst lakes." Master's thesis, 2019. http://hdl.handle.net/10773/25369.
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Lagos de termocarso, resultantes da degradação do permafrost, estão dispersos nas regiões árticas e subárticas, tendo revelado uma crescente contribuição para o ciclo global de carbono ao longo dos últimos 40 anos. O degelo do permafrost resulta na libertação de grandes quantidades de matéria orgânica natural (NOM) para sistemas aquáticos, estando também associado a fenómenos de metanogénese e à consequente libertação de metano para a atmosfera. Matéria orgânica dissolvida (DOM) é uma mistura altamente complexa, estando presente em todos os sistemas naturais aquáticos, apresentando uma composição variável consoante a origem. A pesquisa apresentada neste trabalho tem como objetivo fornecer novas informações relativamente à caracterização estrutural de DOM proveniente de lagos de termocarso em regiões subárticas. Para tal, técnicas de caracterização como espectroscopia de fluorescência, espectroscopia de infravermelho por transformada de Fourier (FTIR), espectroscopia de ressonância magnética nuclear (NMR) e análise elementar (CNHS) foram utilizadas.
As amostras de águas foram recolhidas a diferentes profundidades em três lagos diferentes (SAS-1A, SAS-1B e SAS-2A) no vale Sasapimakwananisikw (SAS), perto da comunidade de Kuujjuarapik-Whapmagoostui (Nunavik, Canadá). Os lagos SAS-1A e SAS-1B estão localizados na margem sul do rio SAS, estando associados à mesma palsa (embora a distâncias diferentes), enquanto que o lago SAS-2A está localizado na margem norte do rio SAS. As amostras de águas foram filtradas, acidificadas, submetidas a um processo de fixação da matéria orgânica e caracterizadas de modo a tentar obter o máximo de informação estrutural. A extrema complexidade das amostras dificultou a obtenção de informação estrutural relativamente às amostras, no entanto, foi possível verificar diferenças entre amostras a diferentes profundidades e de diferentes lagos.
Todas as amostras tenham revelado uma forte componente terrestre, com SAS-1B a demonstrar possivelmente o maior grau de humificação. Os dados de fluorescência pareceram indicar a presença de DOM recente na superfície do lago SAS-1A (ao contrário dos restantes lagos), sugerindo uma nova fonte de matéria orgânica na superfície do lago. Contrariamente ao esperado, o lago SAS-1B, embora mais próximo geograficamente do lago SAS-1A, revelou maiores semelhanças com a composição do lago SAS-2A (com base nos dados de FTIR, RMN e espectroscopia de fluorescência).
Atualmente, verifica-se uma falta de estudos relativamente à caracterização estrutural de DOM proveniente de lagos de termocarso. Assim sendo, os resultados apresentados nesta dissertação fornecem o primeiro passo para uma caracterização mais aprofundada de DOM de lagos de termocarso, com o objectivo de melhor compreender a biogeoquímica destes sistemas.Mestrado em Química
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Pao, Kung-Yuan, and 鮑康元. "A Conjunctive Use Scheme of Groundwater Recharge: A Case Study of Kaoping Artificial Lakes in Southern Taiwan." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/52186179737334097718.
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碩士國立臺灣大學
生物環境系統工程學研究所
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The southern part of Taiwan caused by heavy rains is facing a serious problem of high water turbidity. Because the uneven spatial and temporal distribution of rainfall and the growth of water resources use in southern Taiwan, water shortage in southern Taiwan region is growing serious. To solve the problem of water shortage in southern Taiwan, a conjunctive scheme to make some artificial lakes and reservoirs will be applied to establish the amount of groundwater recharge. In this study, a numerical model MODFLOW is adopted to simulate different scenarios in this area. First, it required pumping test to obtain the hydrogeological parameters of the study area to apply MODFLOW numerical scheme to calibrate, validate and analyze sensitivity of simulation of the four artificial lakes with pumping two different regions. Hill method is selected to evaluate the safe yields under different scenarios in the study area.The relationship between water depth and groundwater recharge is studied in this thesis. Last, a Groundwater Management Index is proposed to be a management reference.
50
Harpur, Cavan Andrews. "Assessing the Natural Variability in the Fish Communities of the Lakes of the Northern Bruce Peninsula." Thesis, 2010. http://hdl.handle.net/1807/24577.
Full textAbstract:
To monitor and assess direct anthropogenic impacts on an aquatic system requires knowledge of its natural variation. The goal of this study explored natural variation in the lake fish communities of the northern Bruce Peninsula, which may act as a reference condition for other studies. The results of this study indicated there has been a shift towards more small-bodied, native species present in the fish communities, potentially a result of beaver activity in the area.
A second goal was to calculate gear sampling efficiencies to enable the design of efficient monitoring protocols for fish communities in small, shallow lakes. It was concluded that a wide variety of gears are required to assess the fish species composition in a lake. Fine-mesh hoops were the most effective gear; however, saturation was never obtained for boat electrofishing; therefore, additional research is required to determine effectiveness relative to the fine-mesh hoop net.