Thesis (Ph. D.)--University of Victoria, 2001. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1989. / Vita. Includes bibliographical references (leaves [145]-152).

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 159-190).

Low-temperature hydrothermal activity in Iceland is apparently mostly controlled by dikes and fractures. Conventional methods of production data analysis are not readily applicable in cases of heterogeneous/anisotropic fracture dominated hydrothermal systems. Moreover, the dikes and fractures may control the heat uptake mechanism of low-temperature activity. The free-surface response functions of analytical reservoir models are presented and methods for analyzing production data on the basis of such models are developed. Based on a homogeneous and isotropic half-space model apparent permeability estimates of 0.7 millidarcy are obtained for two low-temperature systems in Tertiary strata in N-Iceland whereas estimates of 5-20 millidarcy are obtained for two systems in Quaternary strata in SW-Iceland. A vertical two-dimensional flow model is, however, more consistent with the apparent linear dike/fracture control of many hydrothermal systems and results in higher permeability estimates. Methods of simulating long term production data by simple lumped capacitor/conductor ladders based on only production/drawdown data are developed and the responses of analytical as well as real systems are shown to be easily simulated by such simple systems. The parameters of simulation ladders also provide information on global hydrological characteristics of hydrothermal systems. A possible dike/fault controlled source mechanism of low-temperature activity in Iceland is considered. This process involves the downward migration of open sections of unwelded quasi-vertical fractures resulting from cooling and contraction of the adjacent rock, in conjunction with vertical heat transfer in the fracture. The rate of downward migration is estimated and found to depend very strongly on the magnitude of the horizontal regional stress. Stress conditions may therefore determine whether a low-temperature system can evolve at a given location as well as determine the intensity of hydrothermal activity. / Graduation date: 1986

Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisor: George W. Luther, III., College of Marine & Earth Studies. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [87]-101).

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1989. / Includes bibliographical references.

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Ecology and Evolution." Includes bibliographical references (p. 69-81).

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Stephen Craig Cary, College of Earth, Ocean, & Environment. Includes bibliographical references.

Hydrothermal vents are deep-sea hot springs. Vents are home to luxuriant assemblages of animals that colonize the warm venting fluids. High biomass is fed by microbes that use hydrogen sulphide and other reduced chemicals in the vent fluid as an energy source to fix inorganic carbon. Individual vents may persist for a few years to several decades. The specialized animals must find new vents, cope with changing fluid conditions and foster their offspring. The composition and structure of vent communities vary in space and time. My research at Axial Volcano, a seamount on the Juan de Fuca Ridge (JdFR) in the northeast Pacific, aims to find pattern in this variation and to propose viable hypotheses of the mechanisms driving the patterns. Axial is an ideal location as it supports mature vent fields (venting for over 15 years) and young, developing vents initiated by a volcanic eruption in 1998. Thus, I was able to study both temporal and spatial variation in vent communities at the same site and relate patterns of developing assemblages to patterns observed at longer-lived vents. Pattern detection is the first critical step in any community ecology study as it justifies and focuses the search for process. I have refined existing statistical methods and developed novel techniques to test for pattern in vent species distributions and abundances. I modified an existing null model approach and showed that species distributions among sixteen vents differ from random in a long-lived (>15 years) vent field. I also developed a novel null model to confirm that initial patterns of community assembly seven months following the Axial eruption differ from random recruitment of species and individuals to new vents. My description of the community response to the Axial eruption is the first quantitative report of patterns of vent colonization and succession. My work documents that new vents are colonized quickly (within months) and that initial assemblages are variable. However, rapid community transitions and species replacements within the first few years cause new assemblages to resemble mature vents by 2.5 years post-eruption. Three habitat factors correlate with the development of nascent vent assemblages: the recruitment timing of the tubeworm Ridgeia piscesae post-eruption, vent age and vent fluid hydrogen sulphide content. I also describe a new polynoid polychaete discovered colonizing the new vents in high densities. My major contribution to vent community ecology is revealing species patterns through extensive sampling and rigorous statistical methods. These patterns are a necessary step towards understanding the processes that structure vent communities: they direct future research effort towards the key species and generate hypotheses to be experimentally tested. My work also elucidates how vent species respond to habitat destruction and creation, which is critical information for effectively managing Canada's only hydrothermal vent Marine Protected Area on the JdFR. / Graduate