Thesis (M.A.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

This dissertation presents results from 3-D (parallel 2-D) high resolution seismic surveys and associated studies over an area with deep sea gas hydrate occurrence. The study area is located on the accretionary prism of the northern Cascadia subduction zone offshore Vancouver Island, Canada. The major objectives of this study were the imaging of a gas/fluid vent field found in the study area and detailed mapping of the tectonic setting and geological controls on fluid/gas venting. Secondary objectives were the characterization of the gas hydrate occurrence and constraints on the seismic nature of the bottom-simulating reflector (BSR) and its spatial distribution. The main grid was 40 lines at 100 m spacing with eight perpendicular crossing lines of multichannel and single channel seismic reflection, and 3.5 kHz subbottom profiler data. In addition to the main 3-D seismic grid, two smaller single channel grids (25 m spacing) were collected over the vent field. The multichannel seismic data acquired with the Canadian Ocean Acoustic Measurement System (COAMS) streamer required correction for irregular towing depth and shot point spacing. A new array element localization (AEL) technique was developed to calculate receiver depth and offset. The individual receiver depths along the COAMS streamer varied between 10-40 m, which resulted in the occurrence of a prominent receiver ghost that could not be completely removed from the seismic data. The ghost resulted in limited vertical resolution and a coarse velocity depth function. The vent field is characterized by several blank zones that are related to near-surface deformation and faulting. These zones are 80-400 m wide and can be traced downward through the upper 100-200 m thick slope sediment section until they are lost in the accreted sediments that lack coherent layered reflectivity. The blank zones are also characterized by high amplitude rims that are concluded to result from the interference effect of diffractions. These diffractions result due to relatively sharp discontinuities in the sediment physical properties at the blank zone boundary. 2-D vertical incidence seismic modeling suggests an increase in P-wave velocity inside of the blank zone with only minor changes in density. Blanking is believed to be mainly the effect of increased hydrate formation within the fault planes. The faults are conduits for upward migrating fluids and methane gas that is converted into hydrate once it reaches the hydrate stability field. Carbonate formations at the seafloor can also contribute to blanking especially at higher frequencies. Free gas may be present in case of full hydrate saturation or strong fluid flow. Geochemical analyses of pore water and water-column samples carried out in cooperation with Scripps Institute of Oceanography indicate relatively low fluid fluxes of less than 1 mm/yr and there is no heat flow anomaly present over the vent field. Methane concentrations of 20 n-moles/L (about 8 times the ocean background concentration) were detected in water-column samples of the first 100-200 m above the main blank zone of the vent field. Venting is also believed to be strongly episodic with a recently more quiet time. However, the observed carbonate crusts indicate a long-term activity of the vents. / Graduate

Islands are valuable research systems for evolution and conservation, but most work has focused on oceanic islands. Far less study has occurred on near-shore islands where inter-island and island-mainland dispersal is an important microevolutionary process. Further studies in near-shore systems would aid the expansion of island evolutionary theory and conservation initiatives. In this thesis, I studied populations of Song Sparrows (Melospiza melodia) on near-shore islands along the Pacific coast of North America to examine the causes and consequences of dispersal for microevolutionary and ecological processes. Within an island metapopulation, where inter-island distances ranged from 200m to 2km, male and female immigration rates were influenced by adult density and sex ratio respectively, suggesting that intrasexual territoriality influences immigration. Islands differed in immigration levels, with low immigration and high resident recruitment on more isolated islands. I next examine genetic structuring at a larger spatial scale (0-300km). I found that the scale of genetic structuring within continuously distributed populations was less than 10km, suggesting that Song Sparrows are a sedentary passerine. Regional comparisons revealed that holding geographic distance constant, larger genetic distances occur in areas located at subspecific boundaries or across water barriers. The apparent reduction in dispersal to islands had broad-scale consequences. Across Pacific Coast islands, island populations consistently had lower genetic variation than mainland populations. Small and remote island populations tended to have the lowest genetic variation. From an in situ conservation stance, populations on large, remote islands could be important contributors to intraspecific genetic diversity because of high genetic differentiation. Finally, I link genetic structuring with contemporary dispersal and show that migration rates among the Channel Islands are low, suggesting that these islands are demographically independent. The absence of shared mtDNA haplotypes between extant and extinct populations suggests that inter-island migration was historically low, potentially explaining why the two extirpated islands have not been recolonized. Collectively, my thesis results increase our understanding of the mechanisms of divergence on insular populations by examining factors affecting dispersal, the spatial scale of divergence and estimating the consequences of reduced gene flow on islands for broad-scale patterns of genetic variation, microevolution and demographic stability. / Forestry, Faculty of / Graduate

No description available.

Muscle samples from 105 marine mammals stranded along the Oregon-Washington coasts (2002-2009) were tested for levels of total mercury by Cold Vapor Atomic Fluorescence Spectrometry. The total mercury present is predominantly in the form of highly toxic methylmercury. After normalizing muscle tissue to 75% water weight, due to variance in water content, Steller sea lions (Eumetopias jubatus) and northern elephant seals (Mirounga angustirostris) exhibited the highest mean concentrations of total mercury followed by harbor seals (Phoca vitulina), harbor porpoises (Phocoena phocoena), and California sea lions (Zalophus californianus); 0.34 ± 0.278, 0.34 ± 0.485, 0.21 ± 0.216, 0.17 ± 0.169 and 0.15 ± 0.126 mg/kg normalized weight, respectively. Mean normalized values demonstrated limited muscle methylmercury accumulation in these species in the Pacific Northwest. Normalizing muscle mercury concentrations eliminated variability from desiccation, and allowed for a clearer indication of the amount of mercury the animal accumulated before stranding. However, actual wet weight concentrations in some of the stranded carcasses were high enough to pose a risk to scavengers.

Historical. General descriptions of intertidal zonation have been published by many workers for almost all littoral areas, both marine and lacustrine (Doty, 1957; Glynn, 1965; Hedgpeth, 1957; Lewis, 1964; Pennak, 1951). The fact that animal species of the sandy shore are few in number eliminates many complex interspecific reactions, while great numbers of individuals make population studies feasible. In addition to certain general works (Dahl, 1952; Pirrie et al., 1932; Yonge, 1950) a number of papers have discussed causative factors or mechanisms for animal zonation.

Recent research conducted throughout the Northern California Current (NCC) on the ecology of Pacific salmon (Oncorhynchus spp.) indicates that variable ocean conditions affect the community composition of zooplankton in the nearshore environment which, in turn, can affect the quality of prey for fish, sea birds and mammals. Interannual variability in the quality and composition of the copepod community in the NCC during early marine residency of some Pacific salmon populations is related to survival to adulthood. However, copepods make up a small portion of the diet of coho and Chinook salmon, and the mechanistic linkages between ocean climate, zooplankton composition and salmon prey remain unclear. Parasite analysis provides a supplement to traditional diet analysis that can describe the foraging history of a host species. Coho salmon (O. kisutch) and Chinook salmon (O. tshawytscha) serve as hosts to an array of marine parasites acquired through consumption of infected intermediate hosts such as copepods, euphausiids, and planktivorous fishes. Causing little or no harm to their salmon host, the presence of trophically transmitted parasites provides information on the dietary history of their salmonid host beyond the 24 hours associated with traditional diet analysis. This study (1) examined differences in feeding behavior of coho and Chinook salmon during their early marine residency using both stomach and parasite community analyses and (2) tested the hypothesis that variability in ocean circulation patterns (measured through the Pacific Decadal Oscillation, sea surface temperature (SST) and Bakun's upwelling index) and copepod species composition are related to variability in the community structure of trophically transmitted marine parasites found in juvenile salmon. I compared the abundance and species composition of parasites recovered from juvenile Columbia River coho and upper Columbia River summer and fall Chinook salmon captured off the coast of Washington from 2002 to 2009. I also compared interannual variability in parasite assemblages to physical and biological indices of ocean conditions. Coho and Chinook salmon consumed similar prey taxa; however, the species richness and abundance of trophically transmitted parasites indicated that Chinook salmon consumed a greater diversity and abundance of infected prey. In addition, differences in the abundance of fish in the diet and Anisakis simplex, a parasitic nematode known to infect salmon through fish consumption, suggest that Chinook salmon consistently consumed more fish prey than coho. In contrast, coho appeared to consume more euphausiids as indicated by stomach content analysis and increased abundance of the euphausiid parasite, Rhadinorhynchus trachuri. Shifts in the parasite community composition of both coho and Chinook salmon were related to interannual variability in SST and the biomass of southern-origin copepods (r > 0.7, P < 0.05). The acanthocephalan R. trachuri and a tetraphyllid cestode were associated with "warm" SSTs and greater biomass of lipid-poor, subtropical copepods while the nematode A. simplex was more abundant in years of "cold" SST and a relatively low biomass of subtropical copepods. These results provide novel insight into differences in the diet of Columbia River coho and Chinook salmon and illustrate linkages between ocean climate, zooplankton community composition and salmon diet during early marine residency. / Graduation date: 2012

Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, and the Woods Hole Oceanographic Institution), September 2003. / Includes bibliographical references. / The cosmogenic radionuclide ¹⁰Be is a unique tracer of shallow sediment subduction in volcanic arcs. The range in ¹⁰Be enrichment in the Central American Volcanic Arc between Guatemala and Costa Rica is not controlled by variations in ¹⁰Be concentrations in subducting sediment seaward of the Middle America Trench. Sedimentary ¹⁰Be is correlated negatively with ¹⁴³ND/¹⁴⁴Nd, illustrating that ¹⁰Be concentrations varied both between and within cores due to mixing between terrigenous clay and volcanic ash endmember components. This mixing behavior was determined to be a function of grain size controls on ¹⁰Be concentrations. A negative correlation of bulk sedimentary ¹⁰Be concentrations with median grain size and a positive correlation with the proportion of the sediment grains that were <32 [mu]m in diameter demonstrated that high concentrations of ¹⁰Be in fine-grained, terrigenous sediments were diluted by larger grained volcanogenic material. The sharp decrease in ¹⁰Be enrichment in the Central American Volcanic Arc between southeastern Nicaragua and northwestern Costa Rica correlates with changes in fault structure in the subducting Cocos plate. Offshore of Nicaragua, extensional faults associated with plate bending have throw equal to or greater than the overlying subducting sediment thickness. These faults enable efficient subduction of the entire sediment package by preventing relocation of the d6collement within the downgoing sediments. / (cont.) Offshore of Costa Rica, the reduction of fault relief results in basement faults that do not penetrate the overlying sediment. A conceptual model is proposed in which the absence of significant basement roughness allows the d6collement to descend into the subducting sediment column, leading to subsequent underplating and therefore removal of the bulk of the sediment layer that contains ¹⁰Be. Basement fault relief was linearly related to plate curvature and trench depth. The systematic shoaling of the plate from southeastern Nicaragua to northwestern Costa Rica is not explained by changes in plate age for this region. Instead, it is hypothesized that the flexural shape of the plate offshore of southeastern Nicaragua and northwestern Costa Rica represents a lateral response to a buoyant load caused by the thick crust and elevated thermal regime in the Cocos plate offshore of southeastern Costa Rica. / by Robyn K. Kelly. / Ph.D.

This research examines the relationship between understory plant diversity and logs in a Pacific Northwest (PNW) Sitka spruce (Picea sitchensis)-western hemlock (Tsuga heterophylla) old-growth, coastal forest. These forests are renowned for their high forest productivity, frequent wind storms, and slow log decomposition rates that produce unmatched accumulations of coarse woody debris (CWD) yet few studies have examined the relationship between CWD and understory vegetation ecology. My research addressed this topic by comparing understory plant census data between paired fallen log and forest floor sites (n=20 pairs). My objectives were to: 1) determine the influence of substrate type on community composition and diversity, and 2) examine successional pathways and species assemblage patterns on CWD in various stages of decomposition. To meet these objectives I employed non-metric multidimensional scaling (NMDS) ordinations and unsupervised cluster analyses to identify and compare community assemblages on both substrates. These methods revealed similar species diversity and evenness between log and forest floor sites with compositional differences within and between substrates corresponding to habitat availability for colonization and light and moisture gradients. My results also suggest understory successional pathways related to decay class and characterized by an initial abundance of bryophytes, forbs, and seedlings followed by woody shrubs. Understory communities developing on logs also experienced increasing diversity, evenness, and divergence from forest floor communities consistent with log decomposition. These results differ from findings for boreal forests that reveal increasing similarity between substrate communities with increasing decay class. Recommendations for future research include the employment of a more robust sample size and direct measurements of environmental variables. Additional comparator studies are also needed to confirm the effects of forest type and decomposition on the relationship between CWD and forest understory communities. This study demonstrates how fine-scale wind disturbance fosters biodiversity through the creation of CWD substrate. My results and future research are essential for the development of silvicultural models designed to promote biodiversity in PNW coastal forests.

John Charles Fremont conducted five expeditions to the West during a period of twelve years (1842-1854). On four occasions, during three of these expeditions (1843-1844, 1845, and 1854), the explorer entered the Utah region. His explorations in northern Utah in 1843 focused primarily on the scientific analysis and survey of the Great Salt Lake. In 1844, Fremont again entered the Utah area and made scientific observations and calculations about the region, including accurately defining the geographic region known as the Great Basin, the name given it by Fremont. In 1845, Fremont proceeded through Utah while enroute to California and spent a considerable amount of time in the Utah area, once again making significant observations. Finally, during the winter of 1854, the explorer surveyed portions of central and southern Utah with intentions of locating a suitable transcontinental railroad route. In this thesis, each of these expeditions is discussed in detail and summaries given concerning the implications each had on the history of the state.