Thesis (Ph. D.)--University of Montana, 2007. / Title from title screen. Description based on contents viewed Aug. 12, 2008. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xii, 169 p. : ill., maps. Vita. Includes abstract. Includes bibliographical references.

Thesis (M.S.)--Northwest Missouri State University, 2008. / The full text of the thesis is included in the pdf file. Title from title screen of full text.pdf file (viewed on December 17, 2008) Includes bibliographical references.

Thesis (PhD)--University of Montana, 2009. / Title from author supplied metadata. Contents viewed on May 14, 2010. Includes bibliographical references.

Thesis (Ph. D.)--Griffith University, 2004. / Title from PDF title page (viewed on Dec. 10, 2006). Includes bibliographical references (p. 226-247).

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 139-141).

Made available in DSpace on 2014-06-11T19:30:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-19Bitstream added on 2014-06-13T20:00:50Z : No. of bitstreams: 1 araujo_rb_dr_jabo.pdf: 1067716 bytes, checksum: 706c3ec31777349a033e768e87ccffee (MD5) / Na planície de inundação do alto rio Paraná, lagoas marginais são viveiros naturais de espécies comercialmente importantes e habitat preferencial de peixes sedentários e de pequeno porte. No presente estudo, foram investigadas a composição e a abundância de comunidades de peixes em lagoas marginais (temporárias e permanentes) sazonalmente isoladas do rio Turvo, incluindo alterações qualitativas e quantitativas nas estações seca e chuvosa e sua relação com fatores ambientais. O material foi coletado em ambas as estações em seis lagoas marginais. As comunidades de peixes foram analisadas por meio de riqueza de espécies, diversidade e equitabilidade, similaridade qualitativa e quantitativa, e associações ecológicas entre amostras, espécies e variáveis ambientais. Foi registrado um total de 7.456 exemplares, distribuídos em 52 espécies, 40 gêneros, 19 famílias, e cinco ordens. As espécies mais abundantes foram Astyanax altiparanae, Serrapinnus heterodon, Liposarcus anisitsi, Hyphessobrycon eques, and Moenkahausia intermedia. A análise de agrupamento mostrou baixa similaridade entre as lagoas, sugerindo heterogeneidade desses ambientes. A composição e abundância das comunidades de peixes nas lagoas estudadas mostraram acentuada sazonalidade, sendo maiores os valores de riqueza e abundância obtidos na estação chuvosa. A análise de correspondência canônica revelou que temperatura da água, alcalinidade e abundância de anfíbios foram significativamente associadas à estrutura da ictiofauna. / In the Upper Paraná River floodplain, marginal lagoons are natural nurseries of commercially important fish species and preferential habitat of sedentary and small-sized fish species. The composition and abundance of fish communities in seasonally isolated lagoons (temporary and permanent) of the rio Turvo, qualitative and quantitative changes in the dry and rainy seasons, as well as relationship with environmental factors, were investigated. The material was sampled in both seasons in six marginal lagoons. The ichthyofauna was studied through species richness, diversity, evenness, qualitative and quantitative similarities, and ecological associations between the samples and species along an environmental gradient. A total of 7,457 specimens, distributed among 52 species, 40 genera, 19 families, and five orders, were recorded. The most abundant species were Astyanax altiparanae, Serrapinnus heterodon, Liposarcus anisitsi, Hyphessobrycon eques, and Moenkahausia intermedia. Cluster analysis showed a low similarity among lagoons suggesting heterogeneity of these environments. The composition and abundance of fish communities in the studied marginal lagoons showed a remarkable seasonality, with highest values of species richness and abundance obtained in the rainy season. Canonical correspondence analysis revealed that the water temperature, alkalinity, and amphibian abundance were significantly associated with the ichthyofauna structure.

The thesis reports comparison of soil seed bank with actual vegetation in alluvial sites of the upper stream of Lužnice river in respect to three biotopes. The study focuses on two different methods of soil seed bank investigation and aims to reveal the applicability of macrofossil analysis for palaeoecological records and its interpretation.

The construction of levees along the Mississippi River [MR], beginning in the mid-to-late nineteenth century, have isolated the river along many segments from its floodplain. Sediment from the river is currently deposited in the hydrologically connected floodplain [HCF], the area between the channel margin at low water and the levees. Researchers have studied the amount and rates of sediment deposition along the Upper and Lower Mississippi River segments from the headwaters to Pool 22 and from the Ohio River to the delta; however, no such assessments have been undertaken along the Middle Mississippi River [MMR]. This study attempts to fill the knowledge gap by assessing sedimentation along three islands within the Middle Mississippi River National Wildlife Refuge. On these islands two approaches were undertaken to assess sedimentation along the MMR’s HCF: dendrogeomorphology and the DEM of Difference [DoD] approach. The dendrogeomorphic approach uses tree-ring analyses to document and interpret geomorphic processes and the rates at which they are occurring. The DoD approach subtracts an older DEM from a newer DEM in order to see the change in elevation/depth over time. The geomorphology of the islands and then the entire MMR HCF (from the confluence of the Missouri River to Thebes, IL) were mapped. Using the sedimentation rates for the geomorphic landforms from the three study islands, the sedimentation rates and volumes for the aforementioned portion of the MMR’s HCF were estimated. The estimated volume of sediment was then compared to the MMR’s suspended sediment flux to determine how much of the suspended sediment was going into storage within the MMR’s HCF. The dendrogeomorphic and DoD methods for the study islands yielded average sedimentation rates of 13.3-16.9 mm year-1 and 21.5-80.1 mm year-1, respectively. The rates for the individual landforms on the islands using the dendrogeomorphic results ranged from 5.2 mm year-1 for the splay to 21.8 mm year-1 for the natural levee and splay, with a weighted average of 16.6 mm year-1 for the MMR HCF. Using these rates and the likely range of densities for the floodplain sediments, it is estimated that 4.9-6.6 million metric tons of sediment is accumulating within the MMR annually. This is approximately 5.4-7.4% of the average annual suspended sediment load of the Mississippi River at St. Louis. This means that the MMR is a major sediment sink. If these relatively rapid rates of deposition continue, they have the potential to substantially reduce the HCF’s ability to convey and store flood water which will result in increased flood levels and, consequently, flood risk within the MMR’s levee protected floodplain in the coming decades.

The Atchafalaya River Basin (ARB) in Louisiana is the principal distributary of the Mississippi River, and it contains the largest contiguous area of baldcypress-water tupelo swamp forests in North America. After designation of the ARB as a federal floodway following the destructive 1927 Mississippi River (MR) flood, it was extensively modified to accommodate a substantial portion of the MR flow (~30%) to mitigate flooding in southern Louisiana. The resulting reach to system scale modifications for regional flood mitigation, navigation, and hydrocarbon extraction have substantially altered the lateral connectivity between the AR and its floodplain wetlands, threatening the ecological integrity of this globally-important ecosystem. Multiple stakeholder groups agree that restoring flow connectivity is essential to maintaining the basin’s water quality and forest health, and several flow-connectivity enhancement projects (hereafter, project elements) have been proposed by the Atchafalaya Basin Program’s Technical Advisory Group within the Flat Lake Water Management Unit (FLWMU) study area to increase lateral hydrologic connectivity within the management unit and beyond. Additionally, a new flow prescription to improve floodplain habitat has recently been suggested for the ARB. Flow into the ARB is now regulated through the Old River Control Structure (ORCS; operational in 1963), and represents the opportunity for large-scale flow experiments to enhance a multitude of ecosystem services that have been degraded due to anthropogenic alteration. For this study, I compiled existing datasets and constructed a 1D2D hydraulic model to evaluate: 1) if the suggested flow prescription would have the desired inundation impacts; 2) whether the proposed project elements would improve lateral connectivity in the FLWMU; and 3) whether recommended project elements would increase the area suitable for baldcypress recruitment in the study area. To examine the first two research questions above, I examined two scenarios – a baseline scenario to examine current conditions (no restoration projects), and a full-implementation scenario, where all proposed project elements that could be examined at the model resolution were implemented. Comparison of the modeling results for the baseline scenario to the suggested flow prescription goals suggests the overbank discharge and the extreme low-flow targets would have the desired impacts of inundating and drying out of the majority of the FLWMU, respectively. Proxy indicators of enhanced flow connectivity suggest that proposed projects will improve water quality, especially at intermediate to high flow conditions, when ~90% of the FLWMU experiences improved drainage as indicated by higher rates of water surface elevation decrease and lower overall system water volume. The stated objectives of the project elements recommended by the Technical Advisory Group are to improve connectivity and water quality, but another important and related restoration goal for stakeholders includes baldcypress restoration. To examine the third objective, I used a model-derived proxy indicator of habitat improvement (depth reduction) at two key discharges, along with other ecological suitability factors, to determine areas most likely to support baldcypress recruitment. Here, I compared baseline conditions to two alternative restoration scenarios – 1) a targeted implementation scenario where 22 project elements were implemented, and 2) the full-implementation scenario, where all projects that could be examined at the model resolution were implemented. Suitable habitat area for both natural and artificial baldcypress recruitment increased under intermediate flow conditions but remained unchanged for higher discharge conditions. For the intermediate discharge scenario, the full-implementation scenario results in a 2 km2 increase in the class considered most suitable for natural baldcypress regeneration within the calculated recruitment band, and a decrease of ~16 km2 in the areas considered least suitable for the entire FLWMU study area. Coupled with the connectivity results, which indicate that nutrient-rich river water will be exchanged between main channels and the backswamp at a greater range of flows, it appears that project implementation alone will benefit baldcypress recruitment, especially artificial regeneration efforts. However, full project implementation coupled with large-scale flow modifications at ORCS would likely provide maximum benefit for baldcypress restoration efforts that seek to increase the area supportive of natural baldcypress regeneration.