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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Degradation of DDT in lake sediments

O'Connor, Ralph C. January 1983 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 103-113).
132

A comparison of four stocks of lake trout with respect to early development

Horns, William H. January 1983 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 196-202).
133

Dispersal, persistence, and areas of core use of re-introduced juvenile lake sturgeon in the Upper Tennessee river system

Huddleston, Misty Dawn, January 2006 (has links) (PDF)
Thesis (M.S.) -- University of Tennessee, Knoxville, 2006. / Title from title page screen (viewed on June 9, 2006). Thesis advisor: J. Larry Wilson. Vita. Includes bibliographical references.
134

Effect of low level fertilization on microplankton in Arctic LTER lakes

Boyko, Alison Lisa. January 1900 (has links) (PDF)
Thesis (M.S.)--University of North Carolina at Greensboro, 2006. / Title from PDF title page screen. Advisor: Parke A. Rublee.; submitted to the Dept. of Biology. Includes bibliographical references (p. 35-40)
135

Untersuchungen zu gezeitenbedingten Höhenänderungen des subglazialen Lake Vostok, Antarktika

Wendt, Anja. Unknown Date (has links) (PDF)
Techn. Universiẗat, Diss., 2003--Dresden.
136

A survey of the fishery resource of Perch Lake, Monroe County, Wisconsin /

Babros, Timothy E. January 1985 (has links)
Thesis (M.S.)--University of Wisconsin -- La Crosse, 1985. / Includes bibliographical references (leaves 71-78).
137

Geophysical investigations in the English Lake District

Lee, Michael Kenneth January 1990 (has links)
Lake District which define the principal anomalies in considerably more detail than previous widely-spaced observations. The physical properties of the Shap and Skiddaw granites have been analysed from geophysical logs recorded in 300 m deep heat-flow boreholes. New density determinations have been made on outcrop samples from over 350 localities in the western and central Lake District. Samples have been classified in terms of their lithology and lithostratigraphy, and representative in-situ densities have been calculated for the principal formations. The gravity and aeromagnetic data have been interpreted, using a combination of modelling and image processing, in order to study the form and evolution of the Lake District granite batholith and structures within the Skiddaw and Borrowdale Volcanic groups. The modelling studies indicate that Lake District batholith may comprise up to nine separate deep-seated components, and there may be a further five high level intrusions. The Eskdale/Wasdale Granite forms a major component in the western Lake District, and the Shap and Skiddaw granites form separate, steep-sided intrusions on the south-eastern and north-eastern margins of the batholith respectively. Prominent residual gravity anomalies, which coincide approximately with the Scafell, Haweswater and Ulpha synclines of the Borrowdale Volcanic Group, are also tentatively interpreted in terms of separate batholith components, but alternative interpretations in terms of thickened BVG sequences are possible. Further separate components are postulated along the northern side of the batholith and beneath the Haweswater Complex. The Ennerdale Granophyre and Threlkeld Microgranite are modelled as high-level intrusions, in line with previous interpretations, and it is posssible that the Eskdale Granodiorite is also in this category. There is good evidence for a high-level granitic intrusion beneath the Crummock aureole and some evidence for a similar intrusion near Coniston. On a broader scale, the modelling indicates that long wavelength magnetic anomalies are best interpreted in terms of a 'magnetic basement' which represent either a thick layer of pre-Skiddaw Group (magnetic) sedimentary rocks, magnetic crystalline basement, or a combination of both. This 'basement' reaches nearest to the surface in the southern Lake District, deepens northwards beneath the batholith, and approaches nearer to the surface again along the northern margin. The image processing of the potential field data has revealed three important ENE-trending geophysical lineaments across the Lake District {the Crummock, Ullswater and Southern Borrowdales lineaments}. Several prominent, but less extensive, NE-trending lineaments are also visible across the central and western parts of the area. The ENE-trending set appear to divide distinctive tracts within the Skiddaw Group and it seems likely that at least some of the lineaments represent fundamental fractures within the underlying basement which were initiated prior to the Borrowdale volcanism and which influenced the subsequent structural development of the Borrowdale Volcanic Group and the intrusive form of the batholith. It is possible that vertical movement influenced by the pre-existing NE- and ENE-trending lineaments may have initiated the Scafell, Haweswater and Ulpha synclines, and associated anticlines, in the Ordovician, leading to a thicker accumulation of BVG in the synclines and/or the subsequent emplacement of late Ordovician (or early Silurian?) components of the batholith beneath them. Alternatively, it is possible that each was initiated as a volcano-tectonic sag over a separate component of an evolving Ordovician batholith, the position of the batholith components themselves being influenced by earlier structural trends. The geothermal characteristics of Caledonian-age granites in the Lake District and Eastern Highlands of Scotland have been studied (in collaboration with other workers). The study has led to a re-examination of the relationship between heat flow (qO) and heat production (AO) for granites and basement rocks in the UK. The data form four separate clusters on the qO-AO plot; three corresponding to granite batholiths in SW England, northern England and the Eastern Highlands of Scotland, and a fourth to the basement rocks of central England and Wales. A single linear correlation between qo and AO is no longer tenable, and an explanation of the data is proposed in terms of the crustal structure and thermo-tectonic setting of each area. In the case of the granite batholiths the data reflect the contrasting depth extent and radioelement - depth functions of the intrusions. These parameters in turn are related to the magmatic evolution and emplacement history of each batholith and the nature of the crust into which they were emplaced.
138

A contribution to a generic revision of Simochromis and Tropheus (Pisces : Cichlidae) - from Lake Tanganyika, with special reference to the Pharyngeal Apophysis and its taxonomic importance

Axelrod, Glen S January 1978 (has links)
The purpose of this thesis is to investigate the taxonomic status of Simochromis and Tropheue. Material for the study wae collected during three visits to Lake Tanganyika in 1976-1977. Tropheus polli G. S . Axelrod 1977, was found and described, and a new species of Simochromis was found and will be described in a forthcoming paper. Nine colour varieties of Tropheus maorii and three colour varieties of Tropheus duboisi were found and described. A diagnosis and description, with colour photographs, is given using morphometries and meristics of the five species of Simochromis and four species of Tropheus. A dissection and cleaning technique tor the pharyngeal apophysis and lower pharyngeal bone is explained, together with a method for the interpretation of relative bone composition of the pharyngeal apophysis. Photographs are included. The dentition is examined, evaluated and figured. Doubt has been cast upon the taxonomic validity of the composition of the pharyngeal apophysis as an indicator of affinity at the sub familial level. This is shown by its seeming lack of functional relationship, apparent arbitrary variation, interspecific variability in Simochromis and Tropheus, and intraspecific variability in S. diagramma and T. duboisi. Thus, the apophysis cannot be considered a reliable cichlid taxonomic characteristic at any level of classification, unless its validity is Substantiated in each instance. Furthermore, it is considered very probable that the Tropheus-Simochromis species complex is a monophyletic assemblage at the genus level, on the basis of similar dentition and mouth form, which is unique in Lake Tanganyika. It is proposed on phyletic grounds that Simochromis and Tropheus be united into the one genus Tropheus, and that Tropheus be divided into the subgenera , Tropheus (Tropheus) and Tropheus (Simochromis), along the lines of its previous division in two separate genera. Characteristics supporting this division include differences in the anal and dorsal fin meristic counts noted in the original descriptions of the genera. In addition, two modifications of the dentition were found during the course of this study which are not mentioned in any previous literature. It is considered probable, that Tropheus (Tropheus) and Tropheus (Simochromis) are monophyletic sister groups within the Tropheus complex. Pseudosimochromis Nelissen 1977 is not considered to be a taxonomically valid genus on either phyletic or gradistic grounds, and is included within Tropheus (Simochromis). The lower pharyngeal bone of T . (S.) diagramma is considered to be plesiomorphic in tooth arrangement, size and shape. A preliminary worKing hypothesis is established on the basis of the conjectures made and other available information which supports the phyletic relationship suggested by Fryer and lIes (1972). An illustration is given.
139

A contribution to the ecology and systematics of the genus Petrotilapia (Pisces : Cichlidae) in Lake Malawi

Marsh, Alan Clive 20 March 2013 (has links)
The nominal species Petrotilapia tridentiger Trewavas, a rock-frequenting fish from Lake Malawi, occurs in three distinct male and female colour forms at Monkey Bay. Field observations on courtship and aggression indicate that the three colour forms are distinct species. The taxonomy of the three species of Petrotilapia that occur at Monkey Bay is revised. R. tridentiger is redescribed and two new species, P. genalutea and P. nigra, are described. The three species are very similar morphologically and are considered to be sibling species. The only morphological character which reliably separates the three sibling species is live coloration: Live coloration is considered to be an important component of the specific mate recognition systems in Petrotilapia species. The coloration of a further fourteen forms of Petrotilapia is described and it is suggested that these forms are valid species. Space resource partitioning plays an important role in facilitating the coexistence of Petrotilapia sibling species. Space is partially partitioned in terms of depth range. In shallow water, where all three species are sympatric, there are differences in the feeding sites used by the various Petrotilapia forms. Changes in niche breadth and overlap, which are associated with changes in the abundance of epilithic algae, indicate that competition for feeding space occurs between the three Petrotilapia species. The Petrotilapia species partition their resources according to a social dominance hierarchy. Dominant forms, such as territorial males, R. tridentiger females and schooling R. genalutea females, have access to rich food supplies which occur within the territories of certain highly aggressive Pseudotronheus species. are facultative and opportunistic .feeders. Petrotilapia species Speciation in allopatry is considered to be the mechanism which adequately explains the current diversity of the genus Petrotilapia. The importance of an integrative approach to future systematic and ecological research on Lake Malawi cichlids is stressed. / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in
140

A study of the population dynamics, production and potential yield of the sardine Limnothrissa Miodon (Boulenger) in Lake Kariba

Marshall, Brian Eric January 1987 (has links)
The limnology of Lake Kariba, especially those aspects that affect sardine biology, are described. The hydrological regime of the lake is seen as a major influence and may be one of the reasons why the fish are very much smaller in Kariba than they are in Lakes Tanganyika or Kivu. Growth was reassessed and there appeared to be a correlation between rates of growth and limnological parameters. In particular, the fish appeared to grow faster, but smaller, in the man-made lakes and this may be a consequence of food shortages brought about by their hydrological characteristics. Mortality rates were also much higher in Kariba and this tended to support the view that the lake is a relatively unsuitable habitat for the sardines. However, estimates of biomass, expressed in terms of lake volume, contradicted this as they were very similar in both Kariba and Tanganyika. The life history strategy of Limnothrissa in Kariba was therefore to reduce its size and increase its productivity in order to maintain the maximum possible biomass and its very high P/B̄ ratio was probably the means by which this was achieved. In terms of lake volume the predicted yields from the pelagic communities of Kariba and Tanganyika were very similar, equivalent to about 20 000 t annually for Kariba. This is close to the yield predicted by several empirical models and the fishery now appears to be entering a phase where increases in effort will not be matched by increased yields. The mechanisms for controlling effort in the fishery appear to be inadequate and particular concern was expressed about the lack of co-ordination between the Zimbabwean and Zambian fishery authorities in planning the development of this shared resource.

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