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Articles 1 - 25 of 25

Full-Text Articles in Life Sciences

Reproductive Success Of Black Skimmers On An Artificial Island: Effects Of Hatching Date And Feeding Rate, Christopher Alan Gordon Jan 1999

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.


Circadian Rhythms And Melatonin Receptors As Sources Of Individual Variation In Reproductive Photoresponsiveness, Sean Bradford Majoy Jan 1999

Circadian Rhythms And Melatonin Receptors As Sources Of Individual Variation In Reproductive Photoresponsiveness, Sean Bradford Majoy

Dissertations, Theses, and Masters Projects

No abstract provided.


Nest Site Selection Of The Brown-Headed Nuthatch In Virginia, Valerie A. Weiss Jan 1999

Nest Site Selection Of The Brown-Headed Nuthatch In Virginia, Valerie A. Weiss

Dissertations, Theses, and Masters Projects

No abstract provided.


Distribution, Swimming Physiology, And Swimming Mechanics Of Brief Squid Lolliguncula Brevis, Ian K. Bartol Jan 1999

Distribution, Swimming Physiology, And Swimming Mechanics Of Brief Squid Lolliguncula Brevis, Ian K. Bartol

Dissertations, Theses, and Masters Projects

Squids are thought to have physiological and locomotive deficiencies that put them at a competitive disadvantage to fishes and exclude them from inshore, highly variable environments that are rich in nektonic fauna. However, brief squid Lolliguncula brevis may be a notable exception. Trawl surveys revealed that L. brevis, particularly juveniles <6 cm dorsal mantle length (DML), are abundant in the Chesapeake Bay, especially when salinity and water temperature are high, and tolerate a wide range of physical conditions relative to other cephalopods. L. brevis is also different from other cephalopods examined previously because its pattern of oxygen consumption as a function of velocity was found to be parabolic and thus similar to aerial flight, and its swimming costs were competitive with ecologically equivalent fishes. Power-speed curves derived from video footage of swimming squid and hydrodynamic force calculations also were parabolic in shape, with high costs both at low and high speeds because of power requirements for lift generation and overcoming drag, respectively. L. brevis employed various behaviors to increase swimming efficiency and compensate for negative buoyancy, such as swimming in various orientations (e.g., arms-first and tail-first), altering angles of attack of the mantle, arms, and funnel, and using fin activity. Fin motion, which could not be characterized exclusively as drag- or lift-based propulsion, was used over 50--95% of the sustained speed range and provided as much as 78% of the vertical and 55% of the horizontal thrust. Small squid (<3.0 cm DML) used different swimming strategies than larger squid possibly to maximize the benefits of toroidal induction, and aerobic efficiency curves indicated that squid 3--5 cm. DML are most efficient. Brief squid also may take advantage of unsteady phenomena, such as attached vortices, for added lift and thrust. Furthermore, an electromyographic study revealed that L. brevis uses different circular muscle layers for various speeds and like fish has muscular "gears", suggesting that there is specialization and efficient use of locomotive muscle in some cephalopods. Therefore, the presumption that squids are inescapably constrained by a second-rate propulsive system and physiological deficiencies is not applicable to L. brevis.


Morphological, Electrophysiological And Behavioral Investigation Of Visual Acuity Of The Juvenile Loggerhead Sea Turtle (Caretta Caretta), Soraya M. Bartol Jan 1999

Morphological, Electrophysiological And Behavioral Investigation Of Visual Acuity Of The Juvenile Loggerhead Sea Turtle (Caretta Caretta), Soraya M. Bartol

Dissertations, Theses, and Masters Projects

A majority of the research on sea turtle vision focuses on the turtle's ability to perceive shapes, colors and brightness cues on land. However, aerial vision is a minor component of the visual ability of sea turtles, potentially used only when surfacing to breathe, while basking, and during female reproductive activities. For my doctoral dissertation, I examined the aquatic visual acuity of juvenile loggerhead sea turtles (Caretta caretta) by investigating the morphology of the eye, the electrophysiology of response to stimuli, and the behavior to specific stimuli. For the morphological experiments, eyes were obtained from loggerheads, euthanized due to ...


Aspects Of The Biology Of Sea Turtles In The Mid-Atlantic Bight, William C. Coles Jan 1999

Aspects Of The Biology Of Sea Turtles In The Mid-Atlantic Bight, William C. Coles

Dissertations, Theses, and Masters Projects

I present here an investigation of several aspects of the biology of sea turtles in the mid-Atlantic Bight. During 19 years of data collection, included in this study, strandings have increased for all species of sea turtles in Virginia. Most sea turtle strandings occurred during the spring when juvenile turtles migrate into the Bay (Kemp's ridleys had a second significant stranding peak, during fall migration) along the Southern Bay and Virginia Beach Oceanfront. Sea turtles utilize the Chesapeake Bay as a feeding area when the water temperature approaches 20??C, and they leave after the water temperature drops below ...


The Effect Of Seagrass Habitat Fragmentation On Juvenile Blue Crab Survival, Kevin Hovel Jan 1999

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 absence ...


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 Jan 1999

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 Jan 1999

Phylogenetic Implications Of Sporangial Ultrastructure In The Subfamily Lithophylloideae (Corallinales, Rhodophyta), Mark T. Bedell

Dissertations, Theses, and Masters Projects

No abstract provided.


Functional And Molecular Analysis Of Antibody Affinity Maturation In Rainbow Trout (Oncorhynchus Mykiss), Haili Zhang Jan 1999

Functional And Molecular Analysis Of Antibody Affinity Maturation In Rainbow Trout (Oncorhynchus Mykiss), Haili Zhang

Dissertations, Theses, and Masters Projects

No abstract provided.


Spatial And Temporal Distributions Of Organic Matter And Polycyclic Aromatic Hydrocarbons (Pahs) In Surface Waters Of The York River, Va Estuary, Rebecca E. Countway Jan 1999

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 Production And Growth Physiology Of Heterotrophic Bacteria In A Subtropical Coral Reef Ecosystem, Peter Dylan Countway Jan 1999

Carbon Production And Growth Physiology Of Heterotrophic Bacteria In A Subtropical Coral Reef Ecosystem, Peter Dylan Countway

Dissertations, Theses, and Masters Projects

No abstract provided.


Molecular Phylogeny Of Lake Baikal Amphipods, Kenneth S. Macdonald Jan 1999

Molecular Phylogeny Of Lake Baikal Amphipods, Kenneth S. Macdonald

Dissertations, Theses, and Masters Projects

No abstract provided.


Relationships Between Experience, Credentials, Moral Development, Conceptual Level, And Self-Efficacy Of School Counselors, Susan Emilie Halverson Jan 1999

Relationships Between Experience, Credentials, Moral Development, Conceptual Level, And Self-Efficacy Of School Counselors, Susan Emilie Halverson

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 Jan 1999

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.


Bacterial Dynamics And Community Structure In The York River Estuary, Gary Edward Schultz Jr Jan 1999

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 ...


Limitation Of Bacterial Growth By Dissolved Organic Matter And Iron In The Southern Ocean, Matthew J. Church Jan 1999

Limitation Of Bacterial Growth By Dissolved Organic Matter And Iron In The Southern Ocean, Matthew J. Church

Dissertations, Theses, and Masters Projects

No abstract provided.


Habitat Fragmentation In Transplanted Eelgrass (Zostera Marina) Beds: Effects On Decapods And Fish, Alfonso Vollmer Lombana Jan 1999

Habitat Fragmentation In Transplanted Eelgrass (Zostera Marina) Beds: Effects On Decapods And Fish, Alfonso Vollmer Lombana

Dissertations, Theses, and Masters Projects

No abstract provided.


32p-Postlabeling Analysis Of Aromatic Dna Adducts In Hemopoietic Tissues And Blood Of The Mummichog Fundulus Heteroclitus, Wendy L. Rose Jan 1999

32p-Postlabeling Analysis Of Aromatic Dna Adducts In Hemopoietic Tissues And Blood Of The Mummichog Fundulus Heteroclitus, Wendy L. Rose

Dissertations, Theses, and Masters Projects

No abstract provided.


A Comparison Of Size Selectivity And Relative Efficiency Of Sea Scallop Trawls And Dredges, David B. Rudders Jan 1999

A Comparison Of Size Selectivity And Relative Efficiency Of Sea Scallop Trawls And Dredges, David B. Rudders

Dissertations, Theses, and Masters Projects

No abstract provided.


Characterization Of The Defensive Efficacy Of The Sternal Secretion Of Eurycotis Floridana (Walker) (Dictyoptera: Blattidae), Matthew William Turnbull Jan 1999

Characterization Of The Defensive Efficacy Of The Sternal Secretion Of Eurycotis Floridana (Walker) (Dictyoptera: Blattidae), Matthew William Turnbull

Dissertations, Theses, and Masters Projects

No abstract provided.


Frequencies Of Suspension-Feeding Actions Vary With Prey Type In Oreochromis Niloticus (Pisces: Cichlidae), K. Lara Ackermann Jan 1999

Frequencies Of Suspension-Feeding Actions Vary With Prey Type In Oreochromis Niloticus (Pisces: Cichlidae), K. Lara Ackermann

Dissertations, Theses, and Masters Projects

No abstract provided.


Timing Of Spring Migration In White-Throated Sparrows, Karen M. Johnson Jan 1999

Timing Of Spring Migration In White-Throated Sparrows, Karen M. Johnson

Dissertations, Theses, and Masters Projects

No abstract provided.


Diet Composition And Feeding Habits Of Large Striped Bass, Morone Saxatilis, In Chesapeake Bay, John F. Walter Jan 1999

Diet Composition And Feeding Habits Of Large Striped Bass, Morone Saxatilis, In Chesapeake Bay, John F. Walter

Dissertations, Theses, and Masters Projects

No abstract provided.


Indo-Pacific Population Structure Of The Black Marlin, Makaira Indica, Inferred From Molecular Markers, Brett Falterman Jan 1999

Indo-Pacific Population Structure Of The Black Marlin, Makaira Indica, Inferred From Molecular Markers, Brett Falterman

Dissertations, Theses, and Masters Projects

No abstract provided.