Physical Sciences and Mathematics Commons^™

Reciprocal Transplantation Of The Desert Soil Crust: Can It Be Done?, Christina D. Cole

UNLV Theses, Dissertations, Professional Papers, and Capstones

A 100 meter X 100 meter study site was chosen at White Rock Springs in Red Rock Canyon National Conservation Area, Nevada. To examine Syntrichia caninervis, a desert crustal moss, reciprocal transplantations (20 mm and 40 mm diameter cores) were performed between shaded to shaded, exposed to exposed, and shaded to exposed microsites to determine if it was possible to transplant the study organism with reasonable survivorship. Transplants were inspected following rain events for percent hydration, number of dead stems, and change in percent cover. Data indicated that there was a low mortality rate of S. caninervis stems, and few …

Ultraviolet-B Radiation: Effects On Pollen Of 34 Taxa, And Inheritance Patterns And Carryover Of Radiation Response In Arabidopsis, Javad Torabinejad

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Although considerable research has addressed effects of elevated ultraviolet-B (UV-8) radiation on vegetative plant structures and processes, the reproductive biology and patterns of inheritance of UV-B tolerance have received much less attention. I examined the effects of UV-B radiation on pollen of 34 taxa. I also addressed questions concerning the patterns of inheritance of UV-B tolerance in Arabidopsis thaliana and examined potential cumulative carryover effects of UV-B exposure through multiple generations of this species.

In the first study, a significant reduction in pollen germination occurred in only five species, but pollen tube growth in more than half of the species …

Benthic Community Analysis Of Hog Island Bay, Virginia, David James Lewis

Biological Sciences Theses & Dissertations

The benthic infaunal macroinvertebrate communities of Hog Island Bay of the Virginia Eastern Shore were quantitatively sampled at 30 locations on August 31 and September 1, 1995. The primary objectives of this study were: (1) to characterize the subtidal macroinfaunal benthic communities of Hog Island Bay, (2) to examine relationships between abiotic factors and the macroinfaunal communities and (3) to characterize the environmental condition of the system using the Benthic Index of Biotic Integrity (B-IBI) (Weisburg et al. 1997) and the EMAP Benthic Index for the Virginian Province (Strobel et al. 1995).

The ecological condition of Hog Island Bay appears …

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.

The Impacts Of External Nutrient Sources On Marine Phytoplankton In An Eastern Shore Sea-Side Estuary, Claudette Lajoie Jenkins

OES Theses and Dissertations

The Eastern Shore of Virginia (Greens Creek) as well as a large portion of the North Atlantic coastline is characterized by estuarine systems not dominated by large river systems. Instead, small freshwater creeks influence many coastal systems yet little information has been documented on their ecological significance. The focus of this research is to identify the biogeochemical and physical interactions within an estuarine water-column and understand the importance of freshwater sources in governing phytoplankton production. The hypothesis of this research is that increases in external nutrient loading into Greens Creek will not result in an increase in primary production. The …

Sensory Development In Settlement-Stage Larvae Of Caribbean Labrids And Scarids: A Comparative Study With Implications For Ecomorphology And Life History Strategies, Monica R. Lara

Dissertations, Theses, and Masters Projects

The sensory capabilities of settlement-stage fishes are unknown but this information is necessary to studies of larval settlement and recruitment. The morphology of the cephalic lateral line, eye and external olfactory organ of thirteen species of settlement-stage Caribbean labroids was described. Scanning electron images of the cephalic lateral line neuromasts, lateral line canals and olfactory epithelia and histological studies of the retinae and morphological measurements of visual acuity were used to assess the level of sensory development attained at settlement. The sensory capabilities of settlement-stage fishes are discussed in relation to the possible cues settlement-stage fishes may be using to …