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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.
The Effect Of Seagrass Habitat Fragmentation On Juvenile Blue Crab Survival, Kevin Hovel
The Effect Of Seagrass Habitat Fragmentation On Juvenile Blue Crab Survival, Kevin Hovel
Dissertations, Theses, and Masters Projects
Habitat fragmentation leads to small, isolated habitat patches in which ecological processes may differ substantially from those in larger, continuous habitats. Seagrass is a structurally complex but fragmented subtidal habitat that serves as a refuge from predation for juveniles of the blue crab, Callinectes sapidus Rathbun. I compared the effects of eelgrass ( Zostera marina L.) patch size and shoot density on juvenile blue crab survival both before (June) and after (September) shoot defoliation and cownose ray disturbance changed eelgrass habitat, and used artificial seagrass to determine the influence of eelgrass patch size on juvenile blue crab survival in 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 …
Phylogenetic Implications Of Sporangial Ultrastructure In The Subfamily Lithophylloideae (Corallinales, Rhodophyta), Mark T. Bedell
Phylogenetic Implications Of Sporangial Ultrastructure In The Subfamily Lithophylloideae (Corallinales, Rhodophyta), Mark T. Bedell
Dissertations, Theses, and Masters Projects
No abstract provided.
Bacterial Dynamics And Community Structure In The York River Estuary, Gary Edward Schultz Jr
Bacterial Dynamics And Community Structure In The York River Estuary, Gary Edward Schultz Jr
Dissertations, Theses, and Masters Projects
Bacterial community dynamics were investigated over seasonal and basin scales within the York River, VA, estuary. Various parameters characterizing bacterioplankton dynamics were measured weekly at a single station (March 1996 through May 1997) and monthly at six stations (June 1996 through May 1997) spanning the entire salinity gradient (0 - ca. 20 psu over 60 km). Bacterial abundance and production were found to be high throughout the estuary. Bacterial abundance ranged from 4.4 x 108 to 1.3 x 1010 cells-liter-1Incorporation of 3H-thymidine ranged from 10 to 863 pmol-liter-1-hr-1 while 3H-leucine incorporation rates ranged from 25 to 1963 pmol-liter -1-hr-1. Clear …