No description available.

No description available.

No description available.

Sedimentation rate could become a new exploration tool for evaluating the source rock potential of sedimentary basins in frontier regions. Petroleum source rocks are defined on the basis of total organic carbon by weight percent. An analysis of Deep Sea Drilling Project (DSDP) cores indicates that there exists quantitative relationships between sedimentation rate and total organic carbon content in fine grained ancient marine sediments of Jurassic, Cretaceous and Cenezoic age. These relationships are independent of geographic setting, geologic age, and differential compaction, but are highly dependent upon lithology. For any given sedimentation rate, the total organic carbon content increases from calcareous to siliceous to black shale sediments. For each of these lithologies, the total organic carbon content increases with sedimentation rate due to reduced aerobic microbial degradation at higher burial rates. Above a critical sedimentation rate, the total organic carbon content may decrease with increasing sedimentation rate due to a clastic dilution effect. Aerobic microbial degradation, however, continues to be less efficient at higher burial rates. Therefore, even though the total organic carbon content may decrease, the quality of the organic matter preserved and the oil generation and oil migration potential of the sediment may continue to increase with increasing sedimentation rate. Similar relationships have also been established between total organic carbon and grain accumulation rate, and total organic carbon accumulation rate and grain accumulation rate. These relationships support both reduced aerobic microbial degradation and the clastic dilution effect. In the latter case, the lithologic control is less pronounced, and the relationship can be used to determine total organic carbon content even when the lithology is not known. The results of this study have important implications for petroleum exploration in frontier regions. Sedimentation rate and grain accumulation rate could be determined from seismic isopach and velocity data. When the lithology is not known, such as prior to exploration drilling, grain accumulation rates could be used to estimate the total organic carbon content, and the oil generation and oil migration potential of a sedimentary basin. Once the lithology is known, the source rock potential of the basin can be more accurately predicted. Future work should be directed toward testing the application of sedimentation rate and grain accumulation rate in the petroleum exploration of frontier regions. / Graduation date: 1980

Graduation date: 1981

Graduation date: 1982

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1972. / Bibliography: leaves 100-105. / ix, 105 l illus., tables

Harmful algal blooms (HABs) are expanding globally and are anticipated to continue increasing with climate change. Two dinoflagellate species, Margalefidinium polykrikoides and Alexandrium monilatum, form extensive and dense blooms most summers in the lower Chesapeake Bay. Alexandrium monilatum, which produces the toxin goniodomin A, tends to bloom soon after M. polykrikoides, for which a toxin has not yet been identified. Previous laboratory studies and a more limited number of field studies indicate mortality and pathology in multiple shellfish species associated with exposure to M. polykrikoides and A. monilatum. However, the impacts of sequential exposure to both HAB species on marine organisms in the natural environment are less well understood. Local aquaculturists grow oysters under a variety of conditions that may be differentially impacted by HAB exposure. No extensive and controlled studies have been carried out in lower Chesapeake Bay assessing impacts of sequential exposure to M. polykrikoides and A. monilatum blooms on oysters cultured using different aquaculture strategies. The two main objectives of this study were to: 1) investigate M. polykrikoides and A. monilatum as a potential threat to cultured oysters, and 2) inform mitigation strategies to minimize HAB impacts based on current grow-out methods. To address these objectives, oysters were grown in 2017 and 2018 at sites characterized by differing water energetics and HAB dynamics. At all sites during both summers, oysters were grown intertidally and subtidally, and in 2018 were also grown in floating cages at one site. Water quality parameters were monitored, including cell concentrations of M. polykrikoides, A. monilatum, and two other local HAB species known to negatively impact oysters, Karlodinium veneficum and Prorocentrum minimum, along with oyster health and survival. Blooms of M. polykrikoides and A. monilatum occurred at the study sites, but not the reference site, in summer 2017 with cell concentrations that were lower than those quantified in some previous years. In summer 2018, neither species bloomed, providing the opportunity to assess oysters during both a bloom and a non-bloom year. Overall oyster mortality in both summers was relatively low compared to mortality often seen associated with other oyster stressors such as disease. Results indicated oyster health and survival were more impacted by factors indirectly related to HABs, specifically location factors (i.e. site and placement location), temperature, and DO. In both summers, mortality was significantly higher for intertidal oysters, compared to subtidal oysters, suggesting intertidal placement may incur stress in summer. It is unknown whether this intertidal stress may be further compounded during more HAB-intensive years. The results of this study suggest M. polykrikoides and A. monilatum had little impact on the health and survival of oysters cultured in the lower Chesapeake Bay in the summers of 2017 and 2018. More than one year of bloom data is likely necessary, however, to fully evaluate the impacts of M. polykrikoides and A. monilatum as potential stressors to cultured oysters in the context of inter-annual variability and the expanding distribution of these two HABs in the Chesapeake Bay.

Thesis (M. Env. St.)--University of Adelaide, Mawson Graduate Centre for Enivironmental Studies, 1994. / Includes bibliographical references (leaves 127-135).

Thesis (M. Sc.)--University of Adelaide, Dept. of Botany, 1947. / "With three supporting papers." Includes bibliographical references (leaves 159-161).