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A Two-Component Aggregation Model, Thomas A. Chisholm Jr
A Two-Component Aggregation Model, Thomas A. Chisholm Jr
Dissertations, Theses, and Masters Projects
An aggregation model which allows specification of primary particle size, density, and fractal dimension for two different particle types was written. Three stickiness values are used, the stickiness of each particle type to itself and the stickiness between particle types. Aggregation mechanisms considered include differential settling and turbulent shear. The model is used in three forms. In its simplest form, it operates on a closed system with aggregates breaking up when their size approaches the Kolmogorov scale. If the system begins with two types of primary particles, larger aggregates have uniform composition. A second version of the model includes removal …
Reproductive Success Of Black Skimmers On An Artificial Island: Effects Of Hatching Date And Feeding Rate, Christopher Alan Gordon
Reproductive Success Of Black Skimmers On An Artificial Island: Effects Of Hatching Date And Feeding Rate, Christopher Alan Gordon
Dissertations, Theses, and Masters Projects
No abstract provided.
Environmental Stress In Hard Coral: Evaluating Lipid As An Indicator Of Sublethal Stress On Short Time Scales, David Harold Niebuhr
Environmental Stress In Hard Coral: Evaluating Lipid As An Indicator Of Sublethal Stress On Short Time Scales, David Harold Niebuhr
Dissertations, Theses, and Masters Projects
Lipid quality was evaluated in Montastrea spp. under sediment- and heat-stressed conditions to evaluate lipid ratio as an indicator of sub-lethal stress on short time scales. The ratio of storage lipid (wax ester + triacylglyceride) to structural lipid (sterol esters + phospholipid) decreased significantly (0.25 to 0.14, p < 0.01) after experimental sedimentation. FAME analysis of colonies exposed to experimental sedimentation showed a reduction of the algal, 18:3(n-6) and 18:4(n-3), polyunsaturated fatty acid (PUFA) in the polar lipid fraction. This loss of PUFA suggests a loss of algal membrane in sediment-stressed colonies. Lipid quality was similarly measured in M. faveolata over a 10-day period. Mean (n = 20) ratio of storage to structural lipid in M. faveolata dropped from 2.43 to a level of 0.98 immediately following a natural sedimentation event before recovering to levels of 1.4 and 2.9 on post-storm days 2 and 4, respectively. Colonies of M. annularis subject to heat-stress (35??C) exhibited no significant change in storage lipid ratio, while levels of Free Fatty Acids increased significantly from 0.012 (n = 22) to 0.156 mg lipid/g dry tissue (n = 22)(p < 0.05). FAME analysis of tissue lipids extracted from the heat-stressed colonies showed changes in the polar fraction, with significant decreases in the 18:3(n-6), 18:3(n-3), 18:4(n-3), 20:4(n-6) and 20:5(n-3) (p < 0.05) PUFA and subsequent significant increases in the saturated fatty acids, 16:0 and 18:0 (p < 0.05). These changes in lipid quantity and quality indicate possible oxidation and preferential digestion of zooxanthellar membranes. Stress experiments were repeated in M. annularis using VacutainerRTM blood collection tubes to collect micro-tissue samples without destroying skeleton of the sample colonies. A significant decrease in storage: structural lipid ratio after sedimentation was also detected using the micro-tissue technique. This study indicates that the relative abundance of lipid subclass components can indicate sub-lethal environmental stress, on short time scales, in M. annularis and M. faveolata. Furthermore, micro-tissue collection techniques permit repeated monitoring coral colonies to assess the manifestation of stress from first detection of impact at the cellular level to changes in community to changes in community structure detectable over longer time scales.
Geochemistry Of Small Mountainous Rivers Of Papua New Guinea: Local Observations And Global Implications, Megan B. Raymond
Geochemistry Of Small Mountainous Rivers Of Papua New Guinea: Local Observations And Global Implications, Megan B. Raymond
Dissertations, Theses, and Masters Projects
Small, wet mountainous rivers (runoff > 0.63 m yr" 1 , headwater elevation> 1000 m, basin area < 10,000 km2 ) contribute a disproportionate amount of sediment to the global ocean due to their steep high topography, erosive substrate, and often high precipitation. Scattered data have suggested a slight, but statistically insignificant, inverse relationship between total dissolved solid (TDS) yield (T km-2 yr-1 ) and basin area, but small to very small rivers (basin areas< 10,000 km2 ) have been poorly documented. To fill this data gap, as well as to elucidate possible links between weathering and basin hydrology, nine small wet mountainous rivers, basin areas 22 km2-2300 km2 , were sampled in late May 1997 in northeastern Papua New Guinea. TDS concentrations ranged from 75 to 148 mg L-1 , with no correlation to watershed area. The dissolved organic carbon (DOC) and particulate organic carbon (POC) values were low, with a mean DOC value of 135 f.Lmol L-1 ; POC values were lower, averaging 3lf.Lmol L- 1 • TDS data, combined with large wet mountainous river TDS data, demonstrate a significant inverse relationship between TDS yield and basin area. As a result, small wet mountainous rivers contribute a disproportionate amount of TDS, and have the highest TDS yields of any class of river. This observation is attributed to the high runoff of the sampled rivers (-2m yr-1 ), in addition to high rates of chemical weathering, which is facilitated by the erosive substrate and high rates of organic matter remineralization.
Spatial And Temporal Distributions Of Organic Matter And Polycyclic Aromatic Hydrocarbons (Pahs) In Surface Waters Of The York River, Va Estuary, Rebecca E. Countway
Spatial And Temporal Distributions Of Organic Matter And Polycyclic Aromatic Hydrocarbons (Pahs) In Surface Waters Of The York River, Va Estuary, Rebecca E. Countway
Dissertations, Theses, and Masters Projects
No abstract provided.
Carbon Cycling In The York River Estuary: An Isotopic And Mass Balance Approach Using Natural Carbon-14 And Carbon-18 Isotopes, Donald W. Linebaugh
Carbon Cycling In The York River Estuary: An Isotopic And Mass Balance Approach Using Natural Carbon-14 And Carbon-18 Isotopes, Donald W. Linebaugh
Dissertations, Theses, and Masters Projects
No abstract provided.