The thick shelled river mussel (Unio crassus) has a fragmented distribution in southern Sweden. It is a threatened and protected species. In both the Swedish red list and the IUCN Red List of Threatened Species Unio crassus is classified as Endangered (EN). Causes for this classification are for instance differentiated bottom substrate and deterioration in water quality. In this study, habitat preferences of Unio crassus were investigated to assist in future restoration work. The environmental parameters that were used to characterize the habitat in sites with or without Unio crassus were water depth, bottom substrate, water velocity, slope, and shading. In this thesis I focused in bottom substrate and water velocity. Sites with Unio crassus had finer bottom substrate and lower water velocity than sites without (t>2.54, p<0.05, t-test). Most of the sites with Unio crassus had a bottom substrate with a size <4 mm and a water velocity around 0.3-0.5 m/s. These two variables were correlated with each other. When the water velocity was higher, the bottom substrate was coarser. These results are in line with other studies, showing that if the bottom substrate is either too coarse or too fine, it could impact Unio crassus. Too coarse bottom substrate probably results in difficulty in burrowing and too fine most likely results in interfering with respiration and feeding. Earlier studies indicate that the water velocity can have a greater impact on unionids than bottom substrate. Because of the correlation between bottom substrate and water velocity it is not easy to disentangle the importance of each factor.

The thick shelled river mussel (Unio crassus) has a fragmented distribution in southern Sweden. It is a threatened and protected species. In both the Swedish red list and the IUCN Red List of Threatened Species Unio crassus is classified as Endangered (EN). Causes for this classification are for instance differentiated bottom substrate and deterioration in water quality. In this study, habitat preferences of Unio crassus were investigated to assist in future restoration work. The environmental parameters that were used to characterize the habitat in sites with or without Unio crassus were water depth, bottom substrate, water velocity, slope, and shading. In this thesis I focused in bottom substrate and water velocity. Sites with Unio crassus had finer bottom substrate and lower water velocity than sites without (t>2.54, p<0.05, t-test). Most of the sites with Unio crassus had a bottom substrate with a size <4 mm and a water velocity around 0.3-0.5 m/s. These two variables were correlated with each other. When the water velocity was higher, the bottom substrate was coarser. These results are in line with other studies, showing that if the bottom substrate is either too coarse or too fine, it could impact Unio crassus. Too coarse bottom substrate probably results in difficulty in burrowing and too fine most likely results in interfering with respiration and feeding. Earlier studies indicate that the water velocity can have a greater impact on unionids than bottom substrate. Because of the correlation between bottom substrate and water velocity it is not easy to disentangle the importance of each factor.

Made available in DSpace on 2016-06-02T19:29:35Z (GMT). No. of bitstreams: 1 3736.pdf: 1836991 bytes, checksum: ed21198d4a9771d8b0b24ebe5d815099 (MD5) Previous issue date: 2011-05-10 / Universidade Federal de Sao Carlos / This study aimed to compare the ichthyofauna and characterize the physical environmental variables and trophic structure of fishes in tributaries of the Tocantins- Araguaia, state of Goias. The samples were collected in 54 streams and rivers, 28 tributaries of Araguaia River and 26 of Tocantins River. For comparison of the ichthyofauna was used CPUE biomass and for the characterization of the variables were considered the altitude, channel width, luminosity, channel depth, turbidity, water velocity and organic detritus. The trophic structure was determined based on the diet of the fish fauna through analysis of stomach contents and data from literature. The results showed that the biomass of fish fauna present difference between the basins and rivers and streams collected. The analysis showed that the highest values of turbidity and water velocity were more significant for rivers, while in the streams the velocity, luminosity and width were more important. The trophic structure of fish fauna of rivers and streams of the Tocantins-Araguaia was represented by eight trophic guilds (algivore, carnivore, detritivore, herbivore, invertivore lepidophage, omnivore and piscivore), being composed mainly omnivores, invertivores, piscivores and detritivores species of the fishes. The heterogeneity of habitat found in sites sampled may be the main factor for the differences between the rivers and streams studied. For some of the stretches sampled in the basin of Araguaia River are inserted in a flood plain, while those of the Tocantins River basin draining mountainous areas. / Este estudo tem como objetivo comparar a ictiofauna e caracterizar as variáveis físicas ambientais e a estrutura trófica da ictiofauna em tributários da bacia Tocantins- Araguaia, estado de Goiás. As coletas foram realizadas em 54 rios e riachos, sendo 28 tributários da bacia do rio Araguaia e 26 do rio Tocantins. Para a comparação da ictiofauna foi utilizada a CPUE da biomassa e para a caracterização das variáveis foram consideradas a altitude, a largura, a luminosidade, a profundidade, a turbidez, a velocidade da água e o detrito orgânico. A estrutura trófica foi determinada com base no hábito alimentar da ictiofauna através de análise de conteúdo estomacal e dados da literatura. Os resultados mostraram que a biomassa da ictiofauna apresenta diferença entre as bacias e rios e riachos coletados. As análises mostraram que os maiores valores de turbidez e velocidade da água foram mais significativos para os rios, enquanto que nos riachos a velocidade, a luminosidade e a largura foram mais importantes. A estrutura trófica da ictiofauna dos rios e riachos da bacia Tocantins-Araguaia foi representada por oito guildas tróficas (algívora, carnívora, detritívora, herbívora, invertívora, lepidófaga, onívora e piscívora), sendo composta principalmente por espécies onívoras, invertívoras, piscívoras e detritívoras. A heterogeneidade do habitat encontrada nos trechos amostrados pode ser o principal fator para as diferenças encontradas entre os rios e riachos estudados. Pois alguns dos trechos amostrados na bacia do rio Araguaia se encontram inseridos em uma planície inundável, enquanto que estes da bacia do rio Tocantins drenam áreas montanhosas.

No / The local parameters for kerosene–water upward flow are measured in a vertical pipe of 77.8 mm inner diameter at 4200 mm from the inlet(L/D = 54) using hot-film and dual optical probes. The effect of superficial water velocity and volumetric quality on radial distribution of two-phaseflow parameters is investigated. The results show the following: (i) the profiles of volume fraction and drop frequency are very similar, and increasing superficial water velocity at low volumetric qualities (<18.6%) change the profile from a convex shape with peak at the pipe centreline to uniform then to concave shape with peak near the wall; (ii) the profiles of drop cut chord change from a parabolic shape with peak at centreline for lows uperficial water velocities to a flat shape at higher superficial water velocity, and the area-averaged drop diameter decreases with higher superficial water velocities for all volumetric qualities; (iii) velocity profiles for both phases have shapes similar to single phase flow, flatter at higher values of superficial water velocity and volumetric quality and centreline peaked at low superficial water velocities and volumetric qualities; (iv) the slip velocity decreases with radial distance having a peak at centreline and zero values near the wall; (v) introducing kerosene drops into single phasewater flow results in a sharp increase in turbulent intensity, particularly at low water velocity, and the difference between the single phase and two-phase flow turbulence intensities decreases with higher superficial water velocities and (vi) the results show that interfacial area concentration increased with higher volumetric quality and higher number of bubbles thereby increases the contact area between the two phases.

Wood can be added to streams to create microhabitats that provide macroinvertebrates with an opportunity for re-colonization by making the stream more heterogeneous. I examined colonization on wood substrate by macroinvertebrates in semi-natural streams in northern Finland during a three month period. Each of the streams was divided in three sections A, B and C, half of which were provided with wood. The focus has been on whether the density of macroinvertebrates changes with time, along an upstream-downstream direction in the streams, or in streams with two wood sections if macroinvertebrates will colonize the first section with wood that they come in contact with (upstream section) or if they continue downstream to the second section with wood. Wood from Salix sp. was placed in nine of the 18 enclosures during mid-June. Samples of wood were removed from the streams on three different occasions from August to October 2014. A total of 32 taxa were identified from the wood and assigned to functional feeding groups: shredders, scrapers, active filter feeders, passive filter feeders, collectors, miners, piercers and predators. The results showed that collectors, miners and piercers increased in density during the month of October and the abundance of scrapers was higher in the upstream location than in the downstream location. Total number of macroinvertebrates, collectors, passive filter feeders and predators had a higher colonization on the first substrate they came into contact with. / Ved i homogena vattendrag skapar mikrohabitat och ger evertebrater en möjlighet att återkolonisera vattendraget genom att göra vattendraget mer heterogent. Jag har undersökt makroevertebraters kolonisation på ved i semi-naturliga bäckar under en tre månaders-period i norra Finland. Bäckarna var uppdelade i tre sektioner upp-, mellan- och nedströms respektive A, B och C. Av 18 sektioner var nio ved försedda. Jag har fokuserat på om tätheten av evertebrater och diversiteten förändras med tiden, längs bäckarna dvs. uppströms – nedströms, och om makroevertebrater kommer kolonisera den första vedförsedda sektionen de kommer i kontakt med eller fortsätta till den efterföljande vedförsedda sektionen. Ved från Salix sp. placerades i nio inhägnader i mitten på juni. Prov på ved togs vid tre olika tidpunkter under studieperioden från Augusti till Oktober 2014. En totala av 32 taxa identifierades från veden och grupperades i funktionella födogrupper: Sönderdelare, skrapare, aktiva filtrerare, passiva filtrerare, samlare, växtgrävare, växtsugare och predatorer. Resultatet visade att samlare, växtgrävare och växtsugare ökade i täthet under oktober månad samt att skapare föredrog ett uppströmsläge framför de andra två möjligheterna. Totala antalet evertebrater, samlare, passiva filtrerare och predatorer koloniserade det första substratet de kom i kontakt med i större utsträckning än de andra födogrupperna.