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The mid-Atlantic coast region, an area of continental significance to migratory and wintering waterfowl and shorebirds, contains numerous moist-soil impoundments that are managed for waterbirds. Positive relationships between nonbreeding body condition and subsequent survival and reproduction have been documented for waterfowl, yet few evaluations of habitat management consider nutritional value of foods. I assessed 2 types of impoundment manipulation, using nutritional data as a basis for evaluation.Invertebrate and plant seed production were measured in disced and control plots in impoundments at Back Bay National Wildlife Refuge. Seed production was higher (P = 0.0614) in disced (1052 ± 468 kg / ha) than in control (529 ± 226 kg / ha) plots. Discing produced higher Chironomid larva abundance during spring, and higher abundance of Amphipods and non-Chironomid Diptera during fall. Waterbird predation reduced abundance of Chironomid larvae, non-Chironomid Diptera, and Amphipods. The predation effect on Total Invertebrate dry mass was 2x higher in disced than in control areas.Invertebrate production also was measured in habitats denuded by foraging greater snow geese (Anser caerulescens atlantica) at Prime Hook National Wildlife Refuge. Chironomid larvae were 2 -6x more abundant in vegetated habitats than in areas where geese had foraged intensively, but exclosure data showed little effect of shorebird predation on invertebrate abundance. These results suggest that high goose populations can reduce waterbird food availability, and that shorebird use of invertebrates in denuded habitats is low.Mean true metabolizable energy (TME) of moist-soil seeds and invertebrates in blue-winged teal (Anas discors) ranged from -0.18 - 3.47 kcal / g. Correction of means for fiber concentration eliminated negative values, thereby enhancing their practical value.Potential duck use-days predicted using TME and seed production data were about 2x higher for disced than for control areas at Back Bay. Magnitude of the discing effect on duck use-days was largely insensitive to different estimates of seed nutritional value, although substantial variation in absolute measures of potential carrying capacity occurred. Discing positively influenced invertebrate abundance, and quantity and quality of moist-soil seeds produced, and should be considered a viable habitat management approach for both shorebirds and waterfowl. / Ph. D.

Over the past century, the world's rivers have become increasingly impounded to combat water scarcity and fossil-fuel reliance. Large dams have faded from popularity due to their adverse environmental effects, but small ponds and reservoirs continue to be constructed at high rates. Due to limited data regarding their size and flow, it has been difficult to assess how these smaller impoundments impact rivers. This study combined rainfall runoff data from the Chesapeake Bay Model with the unique routing framework of VA Hydro to create a simplistic hydrologic model capable of analyzing impoundment-induced flow alteration. Using standard design techniques and satellite imagery, a methodology was developed to build realistic stage-storage-discharge relationships for small and large impoundments. Eleven impoundments of the Difficult Run watershed were modeled within VA Hydro to assess their cumulative impact on downstream flow. Multiple models were created with different active impoundments and run for the full model period, 1984 - 2005. Flow alteration increased significantly with additional impoundments. Peak flows were attenuated as water was stored behind outlets, but median flows were increased as this water was slowly released. Average storm duration increased due to extended rising and falling limbs caused by impoundment outlets. Headwater channels increasingly ran dry, decreasing extreme low flows due to impoundment evaporation. Large reservoirs had a greater impact on median flows, but smaller ponds dominated low flow alteration. These results suggest that traditional hydrologic assumptions and metrics may be incapable of analyzing a changing flow regime without explicitly considering small and large impoundments upstream. / Master of Science / At first look, dams are an excellent solution to water scarcity and energy independence. They trap clean water and direct it through turbines. Unfortunately, their installation and operation creates many negative environmental impacts by fundamentally altering downstream channels, leading to a loss of fish vitality and river function. Large dam construction has decreased in the US because of these effects, but small dams continue to be built at high rates due to growing agricultural and stormwater demands. Their impact on rivers is less understood due to limited data availability regarding their size and function. This experiment used standard design techniques and widely available satellite data to create a representative model for dams of all size. Multiple tests were run, progressively increasing the number of dams within a watershed and analyzing their impact on downstream flow. With increased impoundment, high floods decreased in magnitude. However, more-typical medium flows increased. River flow became more static, with less extreme floods and more medium flows. The modeled dams greatly decreased drought flows as trapped water evaporated and decreased outflow. This impact was particularly noticeable in ponds that drained only a small area as they took longer to refill after drying. Larger dams more greatly impacted medium flows. These results contribute significantly to water availability prediction by more realistically representing dam processes. Although more work is needed to refine the impoundment modeling strategy, this study has effectively demonstrated that small and large dams affect flow in different manners and need to be accounted for accordingly.

Made available in DSpace on 2017-07-10T14:38:26Z (GMT). No. of bitstreams: 1 louise.pdf: 1784422 bytes, checksum: 60f4897ec789c94dd1c7ec0eda64a208 (MD5) Previous issue date: 2015-02-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / 1. The size spectrum associates the abundance of individuals with the size of their body. The main objective was to investigate the influence of reservoir operation regime on the process of energy transfer in fishes assemblage, testing the hypothesis that the reservoir operation modify the spatial variability of the slopes of the size spectra. 2. For this, samples were carried out the period from January 2005 to December 2007. Data were obtained in eight reservoir with different operation regime, located in the state of Paraná, southern Brazil. To calculate the slopes of fish size spectra we used Pareto I model. The effects of operation regime on the size spectra were evaluate from the paired t test. 3. The results showed that the reservoir operation regime presents significant effect on the size spectra of the fish assemblages, wherein the slopes of spectra indicated that the reservoirs tend to present higher proportions of the small individuals. This effect were more pronounced in the reservoirs that operate in accumulation, indicating less efficient energy transfer through food webs in these environments / O espectro de tamanho associa a abundância de indivíduos com o tamanho do corpo destes. O objetivo principal foi investigar o efeito do regime de operação de reservatórios, sobre o processo de transferência de energia em assembleias ictiícas, testando-se a hipótese de que o regime de operação do reservatório altera a variabilidade espacial das inclinações dos espectros de tamanho, influenciando o fluxo de energia nos distintos reservatórios. Para isso, as amostras foram coletadas no período de janeiro de 2005 a dezembro de 2007. Os dados foram obtidos de oito reservatórios, com diferentes regimes de operação localizados no estado do Paraná, região sul do Brasil. Para calcular as inclinações dos espectros de tamanho de peixes foi utilizado um modelo de Pareto tipo I. Os efeitos dos regimes de operação sobre os espectros de tamanho foram avaliados através do Teste t pareado. Com a análise dos resultados evidenciou-se que o regime de operação do reservatório apresenta efeito significativo sobre os espectros de tamanho das assembleias de peixes, sendo que as inclinações dos espectros indicaram que os reservatórios tendem a apresentar maiores proporções de indivíduos pequenos, sendo esse efeito mais pronunciado nos reservatórios que operam em regime de acumulação, indicando menor eficiência na transferência de energia nesses ambientes

<p>Abstrakt: Jag har undersökt hur älvreglering påverkar mängden knott (Tvåvingar: <i>Simuliidae</i>) längs flera norrlandsälvar och vilka konsekvenser denna påverkan får för den landlevande fågelfaunan. Studien visar att utbyggnad av älvar har en negativ effekt på mängden knott. Det fanns sju gånger högre tätheter av knott längs "orörda älvar" jämfört med utbyggda älvar.</p><p>Skillnaden i antal knott mellan älvtyperna var mycket större för knotthanar än för knotthonor, vilket förklaras av att honorna är rörligare eftersom de flyger och letar efter blod. Knott lever av blod från ett flertal däggdjur och fåglar och visar en stor variation i värd-specificitet mellan olika arter. Jag fann en högre frekvens av haemosporida blod parasiter (<i>Leucocytozoon</i>) i fåglar längs "orörda" Vindelälven jämfört med den reglerade Umeälven. Detta mönster stämmer väl överens med tätheten fågelparasiterande knott som är lägre längs Umeälven. Knott attackerade främst värdar som var stora och vanliga. Fågelsamhällets sammansättning skiljde sig mellan orörda och utbyggda älvdalar. Tätheten av icke insektsätande fåglar tenderade att minska, efter häcksäsongen, längs orörda älvar medan den ökade längs utbyggda älvar. Den insektsätande fågeln svartvit flugsnappare (<i>Ficedula hypoleuca Pallas</i>) uppvisade större häckningsframgång längs orörda älvar jämfört med utbyggda älvar. Detta är förmodligen en effekt av den större mängden insekter som finns längs orörda älvar.</p> / <p>The effects of river regulation on blackfly (Diptera: <i>Simuliidae</i>) abundances and consequences for the avifauna in terrestrial environments were studied along multiple rivers in northern Sweden. I found that impoundment of rivers has detrimental effect to blackfly abundances. The densities of large-river breeding blackfly species were several-fold higher along free-flowing than along regulated rivers. The difference in abundances was much larger in males than blood-seeking females. Blackflies attacked a variety of mammalian and avian hosts and showed different levels of host-specificity between species. I found higher prevalence of haemosporidian blood parasites (<i>Leucocytozoon</i>) in birds along the free-flowing Vindel River in comparison to the regulated Ume River, where the lower densities of ornithophilic blackflies were reduced. Blood-seeking blackflies predominantly attacked large and/abundant hosts.</p><p>Assemblages of birds differed between valleys of regulated and free-flowing rivers. Densities of noninsectivorous birds tended to decrease along free-flowing rivers in the post-breeding season, but increased along regulated rivers at the same time. Insectivorous European pied flycatcher (<i>Ficedula hypoleuca Pallas</i>) showed greater fledging success along free-flowing than regulated rivers, which probably reflects the higher insect abundances found along freeflowing rivers.</p>

Abstrakt: Jag har undersökt hur älvreglering påverkar mängden knott (Tvåvingar: Simuliidae) längs flera norrlandsälvar och vilka konsekvenser denna påverkan får för den landlevande fågelfaunan. Studien visar att utbyggnad av älvar har en negativ effekt på mängden knott. Det fanns sju gånger högre tätheter av knott längs "orörda älvar" jämfört med utbyggda älvar. Skillnaden i antal knott mellan älvtyperna var mycket större för knotthanar än för knotthonor, vilket förklaras av att honorna är rörligare eftersom de flyger och letar efter blod. Knott lever av blod från ett flertal däggdjur och fåglar och visar en stor variation i värd-specificitet mellan olika arter. Jag fann en högre frekvens av haemosporida blod parasiter (Leucocytozoon) i fåglar längs "orörda" Vindelälven jämfört med den reglerade Umeälven. Detta mönster stämmer väl överens med tätheten fågelparasiterande knott som är lägre längs Umeälven. Knott attackerade främst värdar som var stora och vanliga. Fågelsamhällets sammansättning skiljde sig mellan orörda och utbyggda älvdalar. Tätheten av icke insektsätande fåglar tenderade att minska, efter häcksäsongen, längs orörda älvar medan den ökade längs utbyggda älvar. Den insektsätande fågeln svartvit flugsnappare (Ficedula hypoleuca Pallas) uppvisade större häckningsframgång längs orörda älvar jämfört med utbyggda älvar. Detta är förmodligen en effekt av den större mängden insekter som finns längs orörda älvar. / The effects of river regulation on blackfly (Diptera: Simuliidae) abundances and consequences for the avifauna in terrestrial environments were studied along multiple rivers in northern Sweden. I found that impoundment of rivers has detrimental effect to blackfly abundances. The densities of large-river breeding blackfly species were several-fold higher along free-flowing than along regulated rivers. The difference in abundances was much larger in males than blood-seeking females. Blackflies attacked a variety of mammalian and avian hosts and showed different levels of host-specificity between species. I found higher prevalence of haemosporidian blood parasites (Leucocytozoon) in birds along the free-flowing Vindel River in comparison to the regulated Ume River, where the lower densities of ornithophilic blackflies were reduced. Blood-seeking blackflies predominantly attacked large and/abundant hosts. Assemblages of birds differed between valleys of regulated and free-flowing rivers. Densities of noninsectivorous birds tended to decrease along free-flowing rivers in the post-breeding season, but increased along regulated rivers at the same time. Insectivorous European pied flycatcher (Ficedula hypoleuca Pallas) showed greater fledging success along free-flowing than regulated rivers, which probably reflects the higher insect abundances found along freeflowing rivers.

Longshore sediment transport rate was measured during energetic sea breeze activity, on intermediate-to-reflective sandy beaches in Southwestern Australia. Estimates of suspended load were obtained using backscatter sensors, current meters and streamer traps. Total load was determined using fluorescent tracer sand and an impoundment study. The measurementsw ere cross-compareda nd usedt o evaluates everalw idely-used longshore transport equations. The streamer trap measurement revealed an exponential distribution of the suspended sediment flux with vertical mixing decreasing in the onshore direction. A continuous time series of the longshore suspended sediment flux across the surf zone was obtained by combining the streamer trap measurements with data collected using surf zone instruments. Comparison of the suspended longshore flux with the total longshore flux derived from the dispersal of the sand tracer indicated that the relative contribution of the suspendedlo ad to the total load was at least 59 %. The movement of sandt racer on four different beaches demonstrated that nearshore sediments were transported obliquely across the surf zone, challenging our conventional view of dividing nearshore sediment transport into cross-shore and longshore components. Furthermore, tracer was found to move from the outer surf zone to the swash zone and vice versa, indicating a cross-shore sediment exchange. The contribution of the swash zone to the total longshore flux was estimated around 30-40 %. Despite large differences in the temporal and spatial scales of the measurement techniques, the littoral drift rates are comparable, suggesting a northward transport rate of 138,000-200,000 m3 year-1. Longshore sediment transport during sea breezes is mainly the result of a high longshore energy flux exerted by wind waves. This is accurately predicted by the equations of Inman and Bagnold (1963) and CERC (1984). The bimodal wave field, characteristic of Southwestern Australia, renders the Kamphuis (1991b) formula unsuitable in this instance.

Two years before impoundment, the trophic status of Lake Ray Roberts was predicted by applying the total phosphorus input into the Organization for Economic Cooperation and Development (OECD) eutrophication model. Predicted mean summer epilimnetic (MSE) chlorophyll a of Elm Fork arm, Isle duBois arm and Main Body were in the eutrophic category of the OECD model. Observed MSE chlorophyll a two years after impoundment of Elm Fork arm, Isle duBois and Main Body had not reached their predicted means and were at the mesotrophic-eutrophic boundary of the OECD model. Six years after impoundment, observed MSE chlorophyll a for Main Body, was closer to its predicted mean and in the eutrophic category of the OECD model. Six years after impoundment, Elm Fork arm was the most productive area of Lake Ray Roberts. Observed means of chlorophyll a, total phosphates, suspended solids and turbidity were often highest in the Elm Fork arm. Wastewater effluent from Gainesville and Valley View, TX, had an impact on productivity in Elm Fork arm.

Please read the abstract in the section 00front of this document / Thesis (PhD(Geotechnical))--University of Pretoria, 2008. / Civil Engineering / PhD / unrestricted