Unionoid mussels are globally threatened and their conservation requires species-specific knowledge on their ecology and parasite-host interaction. Unio crassus is one of Europe’s most threatened unionoid species and has a temporary obligate parasitic life stage (glochidia) on fish. A lack of suitable hosts is probably a major limitation for mussel recruitment, but host species composition, suitability and availability in time and space have yet to be fully explored. This thesis examines different aspects of the host fish species, including their composition, suitability and ecological importance, in relation to U. crassus, using both field and laboratory studies. The effects of mussel and host density on mussel reproductive potential were considered, as were aspects of evolutionary adaptations between mussels and fish and how climate change may affect their interaction. The results show that U. crassus is a host generalist, parasitizing a variety of fish species. Host suitability and density, which varied among fish species and rivers, affected the level of glochidia encapsulation, hence mussel reproductive potential, more so than the density of mussels taking part in reproduction. Ecologically important hosts included both highly suitable primary hosts, and less suitable hosts that were highly abundant. Whether or not U. crassus has specific adaptations to its hosts to enhance juvenile transformation remains unclear. No distinct pattern of local adaptation was found, nor was there an effect of host fish presence on the timing of glochidia release by adult mussels. Instead, temperature played a major role, with results suggesting that changes in spring water temperature regimes can cause temporal and spatial mismatches in the mussel-host interaction. This thesis indicates that investigations of local mussel-host interactions help in identifying mechanisms important for unionoid conservation management and prioritization. / Många sötvattenmusslor har en komplex livscykel där larverna (glochidier) under sin utveckling till frilevande musslor parasiterar på gälarna hos lämpliga värdfiskar. Flera av våra musslor, såsom den tjockskaliga målarmusslan (Unio crassus), är globalt hotade och för att kunna bevara och förvalta dessa arter på bästa sätt behöver vi lära oss mer om deras ekologi och samspelet mellan musslan och dess värdfiskar. Avsaknaden av värdfiskar innebär förmodligen en stor begränsning för rekryteringen av juvenila musslor, men det finns trots detta en begränsad kunskap om hur artsammansättningen i fisksamhället och dess tillgänglighet påverkar musselpopulationer.  Min avhandling undersöker olika aspekter av interaktioner mellan U. crassus och dess värdfiskar, som hur värdfisksamhällen och fiskarters värdlämplighet påverkar musslans reproduktionspotential. Jag har även studerat hur tätheter av olika fiskarter och vuxna musslor påverkar rekryteringen, eventuella evolutionära anpassningar samt om en förhöjd temperatur skulle kunna påverka interaktionen mellan U. crassus och dess värdfiskar. Resultaten visar att U. crassus är en generalist som parasiterar på en mängd olika fiskarter. Jag fann dock en stor variation i dominerande fiskarter och lämpliga värdar mellan olika åar, vilket påverkade reproduktionspotentialen hos musslorna mer än vad tätheten vuxna musslor som deltog i reproduktionen gjorde. Som ekologiskt viktiga värdar fanns således både särskilt lämpliga, primära värdarter, men också mindre lämpliga arter som förekom i höga tätheter. Ingen tydlig lokal anpassning kunde observeras, och fiskens närvaro påverkade inte tidpunkten för när de vuxna musslorna släppte sina glochidielarver. Däremot fann jag att temperaturen spelade en viktig roll för musslans reproduktion, där ökad temperatur föreslås ha negativa effekter på interaktionen mellan musslan och dess värdfiskar. Avhandlingen visar på vikten av att studera interaktioner mellan den tjockskaliga målarmusslan och dess värdar på lokal skala för att bättre kunna identifiera och prioritera viktiga naturvårdsåtgärder. / UnioCrassusforLIFE (European LIFE+ project: LIFE10 NAT/SE/000046)

Made available in DSpace on 2017-07-21T18:15:27Z (GMT). No. of bitstreams: 1 WolliverDias.pdf: 3685063 bytes, checksum: 2953027d085ff6193c938c6c73f7b42d (MD5) Previous issue date: 2012-04-26 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / The banks erosion in river is in the most dynamic processes of the landscape and can be influenced by several factors. The bank erosion is a result of the interaction between the ravines conditions and the fluvial characteristics. Therefore, erosion rates are determined by the ravines resistance against the potential erosive flow. The adjacent land use is also a determining factor in erosion processes, once the protection exerted by riparian vegetation ceases to exist when it is replaced for other ends. This study aimed to analyze the dynamics of banks erosion along the Guabiroba River located in Guarapuava - PR. However, it was considered the physical parameters of the evaluated sections: material texture, ravines face resistance, slope, and the fluvial stream characteristics. The estimated margins erosion was performed by monitoring erosion pins (volumetric technique). Thus, it was possible to quantify rates of river banks erosion at Guabiroba River, as well as identify and classify the occurring erosion processes. The material loss value along the river banks at Guabiroba River was approximately 1684.7 tons, registered between October 2010 and January 2012, mainly represented by the interaction of corrosion processes and undermining. / A erosão das margens de rios encontra-se entre os processos mais dinâmicos da paisagem, podendo ser influenciado por diversos fatores. A erosão das margens é resultado da interação entre as condições dos barrancos e das características fluviais. Assim, as taxas de erosão são determinadas pela resistência do barranco frente ao potencial erosivo do fluxo. O uso da terra nas adjacências também é determinante nos processos erosivos, tendo em vista a proteção exercida pela vegetação ripária que deixa de existir quando as matas ciliares são substituídas por outros usos. O presente trabalho buscou analisar a dinâmica da erosão de margens plenas ao longo do rio Guabiroba, localizado no município de Guarapuava - PR. Para tanto, levou-se em consideração os parâmetros físicos das seções avaliadas: textura do material, resistência da face do barranco, declividade e características do canal fluvial. A estimativa da erosão das margens foi realizada através do monitoramento dos pinos de erosão (técnica volumétrica). Desta forma, foi possível quantificar as taxas de erosão das margens do rio Guabiroba, bem como identificar e classificar os processos erosivos ocorrentes. O valor de perda de material ao longo das margens do rio Guabiroba foi de aproximadamente 1684,7 toneladas, registrados entre outubro de 2010 e janeiro de 2012, representados principalmente pela interação dos processos de corrasão e solapamento.

Accurate models to reliably predict sediment and chemical transport in watershed water systems enhance the ability of environmental scientists, engineers and decision makers to analyze the impact of contamination problems and to evaluate the efficacy of alternative remediation techniques and management strategies prior to incurring expense in the field. This dissertation presents the conceptual and mathematical development of a general numerical model simulating (1) sediment and reactive chemical transport in river/stream networks of watershed systems; (2) sediment and reactive chemical transport in overland shallow water of watershed systems; and (3) reactive chemical transport in three-dimensional subsurface systems. Through the decomposition of the system of species transport equations via Gauss-Jordan column reduction of the reaction network, fast reactions and slow reactions are decoupled, which enables robust numerical integrations. Species reactive transport equations are transformed into two sets: nonlinear algebraic equations representing equilibrium reactions and transport equations of kinetic-variables in terms of kinetically controlled reaction rates. As a result, the model uses kinetic-variables instead of biogeochemical species as primary dependent variables, which reduces the number of transport equations and simplifies reaction terms in these equations. For each time step, we first solve the advective-dispersive transport of kinetic-variables. We then solve the reactive chemical system node by node to yield concentrations of all species. In order to obtain accurate, efficient and robust computations, five numerical options are provided to solve the advective-dispersive transport equations; and three coupling strategies are given to deal with the reactive chemistry. Verification examples are compared with analytical solutions to demonstrate the numerical accuracy of the code and to emphasize the need of implementing various numerical options and coupling strategies to deal with different types of problems for different application circumstances. Validation examples are presented to evaluate the ability of the model to replicate behavior observed in real systems. Hypothetical examples with complex reaction networks are employed to demonstrate the design capability of the model to handle field-scale problems involving both kinetic and equilibrium reactions. The deficiency of current practices in the water quality modeling is discussed and potential improvements over current practices using this model are addressed.