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Patterns Of Reef Fish Larval Supply To Petroleum Platforms In The Northern Gulf Of Mexico., James Marvin Tolan
Patterns Of Reef Fish Larval Supply To Petroleum Platforms In The Northern Gulf Of Mexico., James Marvin Tolan
LSU Historical Dissertations and Theses
Surveys of ichthyoplankton assemblages were conducted from four oil and gas platforms located in the northern Gulf of Mexico from November 1994 through July 1997. Diurnal collections, supplemented with light trap collections from the surface and -20 m depth, were taken quarterly during 1994 and 1995. Quarterly ichthyoplankton sampling at dawn and dusk only during 1996 and 1997 were supplemented with surface "lighted plankton net" collections. Of the 36,676 individuals collected, epipelagic (neretic and oceanic Clupeiformes, neretic Carangidae and Lutjanidae, as well as oceanic Scombridae) and mesopelagic (Myctophidae and Gonostomatidae) families comprised the majority of the ichthyoplankton. Reef-dependent (e.g., Pomacentridae, …
Spatial Variability And Isotopic Studies Of The Prairie -Forest Transition Soil In Louisiana., Asfaw Bekele
Spatial Variability And Isotopic Studies Of The Prairie -Forest Transition Soil In Louisiana., Asfaw Bekele
LSU Historical Dissertations and Theses
The calcareous prairies of Louisiana are among the most endangered ecosystems in North America. The major threat to this ecosystem is the invasion by woody and herbaceous plants, primarily eastern red cedar (Juniperus virginiana ). The restoration and management of these rare plant communities require a thorough understanding of the soils supporting them. Geostatistical, fractal, and stable isotopic procedures were integrated to study the soil and vegetation spatial variability. The prairie soil was alkaline, the forest soil was acidic, and the transition soil was neutral. The spherical model described the spatial variability of virtually all the soil properties considered with …
The Relationship Of Biomass Allocation And Nutrient Dynamics In Loblolly And Slash Pine Forests., Christopher Ashley Dicus
The Relationship Of Biomass Allocation And Nutrient Dynamics In Loblolly And Slash Pine Forests., Christopher Ashley Dicus
LSU Historical Dissertations and Theses
Aboveground biomass allocation and its effect on various aspects of N and P dynamics were investigated in loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) stands planted at different spacings. Further, the relationship of nutrient demand and root production was investigated to validate the functional balance hypothesis in forest stands. N mineralization was greater in loblolly pine stands than slash pine, corresponding with greater needle litter N concentration. Both N and P mineralization increased in loblolly pine stands with increasing stand density, the result of greater nutrient input through increased litterfall. There were no species differences in …
A Case Study In Amazonian Biogeography: Vocal And Dna -Sequence Variation In Hemitriccus Flycatchers., Mario Cohn-Haft
A Case Study In Amazonian Biogeography: Vocal And Dna -Sequence Variation In Hemitriccus Flycatchers., Mario Cohn-Haft
LSU Historical Dissertations and Theses
Ongoing debate about the evolutionary history of the Amazonian avifauna suffers from a shortage of data. Especially needed are thorough geographic sampling, sensitive markers of genetic diversity, and historical data in the form of explicit phylogenies. I examined patterns of geographic variation in three widespread species complexes of nearly identical Amazonian flycatchers in the genus Hemitriccus, based on spectrographic analysis of vocalizations and phylogenetic analysis of DNA sequences (1026 base pairs of cytochrome b from 44 individuals) from throughout Amazonia. Although members of the three complexes are extremely difficult to distinguish morphologically and have long been confused by taxonomists, they …
Suspended Sediment And Nutrient Flux Dynamics In Fourleague Bay, Louisiana: The Role Of Winter Cold Fronts And Atchafalaya River Discharge., Brian Christopher Perez
Suspended Sediment And Nutrient Flux Dynamics In Fourleague Bay, Louisiana: The Role Of Winter Cold Fronts And Atchafalaya River Discharge., Brian Christopher Perez
LSU Historical Dissertations and Theses
Material concentrations and fluxes in Oyster Bayou, a tidal channel connecting Fourleague Bay, Louisiana and the northern Gulf of Mexico, were sampled every three hours for 3-months, to examine the importance of atmospheric cold fronts and riverine forcing on the functioning of this estuarine system. The Atchafalaya River was the primary source of nitrate+nitrite (NO2+NO3), total nitrogen (TN), and total phosphorus (TP) to the estuary with greater influence associated with northerly post-frontal winds. Riverine influence coupled with wind-forced resuspension events led to the greatest concentrations of total suspended sediment (TSS) and particulate organic carbon (POC). Ammonium (NH4) concentrations were highly …
American Alligator Nesting Ecology In Impounded Marsh Habitat, Louisiana., Steven Richard Reagan
American Alligator Nesting Ecology In Impounded Marsh Habitat, Louisiana., Steven Richard Reagan
LSU Historical Dissertations and Theses
The goal was to monitor a large number of female alligators over a 3-year period to obtain information on alligator nesting ecology. This dissertation, although designed to estimate annual nesting rates, provides additional meaningful information on methods of capture, tag retention rates, nest spacing patterns, segregation of size classes, nest site fidelity, the relationship between attendance and nest success, the effects of fire ants on alligator nest success, the relationship between hatchling alligators and their mother, and hatchling dispersal. Passive integrated transponder (PIT), monel web, and cranial mounted reflector tags were evaluated for marking and identifying alligators. Use of harmonic …
Habitat And Demography Of Understory Trees In Mixed Species Hardwood Forests In Northern Florida, United States Of America., Charles Kwit
Habitat And Demography Of Understory Trees In Mixed Species Hardwood Forests In Northern Florida, United States Of America., Charles Kwit
LSU Historical Dissertations and Theses
Temperate mixed-species hardwood forests of northern Florida, USA, contain a high diversity of understory tree species, some of which have been hypothesized to require disturbance (e.g., hurricanes and/or treefall gaps). Taxus floridana is a rare understory conifer endemic to midslopes of ravines of the Apalachicola River Bluffs, and is found primarily on north-facing slopes. Vegetation sampling in the southern portion of T. floridana's range revealed the presence of an upslope oak-hickory community of suggested recent origin, and higher densities of American beech (Fagus grandifolia ), southern magnolia (Magnolia grandiflora), and evergreen understory trees on north-facing midslopes with T. floridana than …
Diversity And Spatial Analysis Of Passerine Birds In Relation To Habitat Characteristics Of Woods Along The Northern Coast Of The Gulf Of Mexico., Jose Luis Alcantara
Diversity And Spatial Analysis Of Passerine Birds In Relation To Habitat Characteristics Of Woods Along The Northern Coast Of The Gulf Of Mexico., Jose Luis Alcantara
LSU Historical Dissertations and Theses
I studied the ecological diversity and spatial patterns of passerine birds during the springs of 1993, 1994, and 1995 at 3 stopover sites on the Chenier Plains of Louisiana and Texas. A "control" stand with dense understory vegetation and a "reduced" stand with modified understory were at each site. Data were collected on the structure and composition of vegetation and on the abundance and location of birds. Species richness, dominance, and diversity indices were computed for both vegetation and birds. Patterns of floristic impoverishment, greater dominance, and greater plant species diversity were found at the "reduced" stands. "Control" vegetation did …
Comparative Biology And Ecology Of The Formosan Subterranean Termite, Coptotermes Formosanus Shiraki (Isoptera: Rhinotermitidae) In Louisiana., Huixin Fei
LSU Historical Dissertations and Theses
A laboratory study was conducted to investigate the effects of sibship patterns and different origins of colonies on mate mortality and growth of incipient colonies in the subterranean termite, Coptotermes formosanus Shiraki. Primary reproductives from New Orleans in nonsibling pairs had significantly higher mortality than sibling pairs. The average egg production for sibling and nonsibling pairs showed no overall significance in the first oviposition period, however, the average number of larvae was consistently higher in nonsibling than in sibling-founded colonies from New Orleans. After two years, the average number of eggs or larvae present in nonsibling-founded colonies was significantly higher …
Processes Controlling Nutrient Transport In The Southeastern Everglades Wetlands, Florida, United States Of America., Martha Ann Sutula
Processes Controlling Nutrient Transport In The Southeastern Everglades Wetlands, Florida, United States Of America., Martha Ann Sutula
LSU Historical Dissertations and Theses
The purpose of this dissertation was to investigate the processes that control material transport in the Southeastern (SE) Everglades and exchange with Florida Bay. Specifically, the objectives were to: (1) determine the factors controlling the spatio-temporal trends in material concentration and exchange; (2) estimate the annual nutrient and carbon export from the SE Everglades; and (3) determine the relative importance of surface water, atmospheric deposition, groundwater, and intrasystem cycling as sources and losses of nutrients to the watershed. Patterns in material exchange were observed for 2.5 years in three of five major creeks draining the SE Everglades. Statistical methods were …
Experimental Mammalian Predator Removal And Other Factors Affecting Dabbling Duck Reproduction In North Dakota., Pamela Renee Garrettson
Experimental Mammalian Predator Removal And Other Factors Affecting Dabbling Duck Reproduction In North Dakota., Pamela Renee Garrettson
LSU Historical Dissertations and Theses
In the prairie pothole region, high predation rates often reduce duck nest success below the 15--20% thought necessary for population stability. Lethal removal of mammalian predators of duck nests is one potential management option, but there is little reliable information about the effects on nest success of removing mammalian predators without using poisons. On 16 4,150-ha blocks, half of them trapped during spring and summer, I found higher ( P < 0.001) nest success on trapped sites (45%) than on untrapped sites (17%). There were no year (P = 0.296), year-treatment (P = 0.423), or species-treatment (P > 0.895) effects. Nest success of blue-winged teal (Anas discors) and gadwalls (A. strepera) was higher than that of mallards ( A. platyrhynchos) and pintails (A. acuta, P = 0.028) on …
Systematics, Ecology, And Social Biology Of The Musk Duck (Biziura Lobata) Of Australia., Kevin Grant Mccracken
Systematics, Ecology, And Social Biology Of The Musk Duck (Biziura Lobata) Of Australia., Kevin Grant Mccracken
LSU Historical Dissertations and Theses
Musk Ducks (Biziura lobata) exhibit a number of unusual morphological and behavioral traits. The most notable of these include: greatly abducted hind-limbs for underwater swimming efficiency, extreme sexual size dimorphism and pronounced structural dimorphism, lek display activity, elaborate sexual display repertoires, and the distinctly non-waterfowl-like trait of provisioning young with all their food from the time of hatch until fledging. Despite such peculiarities and obvious theoretical potential in the areas of comparative morphology, sexual selection, and brood ecology, few studies of Musk Ducks have been undertaken, and those to date have been either small in scope and design, or focused …
The Tiger And The Pangolin: Cultural Ecology, Landscape Ecology, And Nature Conservation In China's Southeast Uplands., Christopher Reed Coggins
The Tiger And The Pangolin: Cultural Ecology, Landscape Ecology, And Nature Conservation In China's Southeast Uplands., Christopher Reed Coggins
LSU Historical Dissertations and Theses
The Wuyi-Daiyun Mountains, which form the core of China's Southeast Uplands Region, support a mosaic of subtropical forest, grassland, and cropland habitats, with some 1,620 species of plants and 326 species of terrestrial vertebrates. Forty-two animal species are officially protected, including the highly endangered South China tiger (Panthera tigris amoyensis). This study, based on one year of field research, examines relationships between village land use, landscape change, and wildlife management in the Meihuashan Nature Reserve of Southwest Fujian. It includes comparative studies of reserves in Longxishan and Wuyishan, further north, and Daiyunshan, to the east. Over 500 local gazetteer records …
The Nature And Extent Of Species Interactions With The United States Gulf Menhaden Fishery., Janaka Anthony De Silva
The Nature And Extent Of Species Interactions With The United States Gulf Menhaden Fishery., Janaka Anthony De Silva
LSU Historical Dissertations and Theses
I employed categorical techniques to explain patchy data on the releasable bycatch in the U.S. Gulf of Mexico menhaden fishery looking for species and areas of potential concern and potential solutions. For fishing grounds east of the Mississippi River, the odds of observing sets with high bycatch in spring and summer were greater than in the fall. Furthermore, spring bycatch rates were higher east of 89°W than in areas west of 93°W. Correspondence analysis indicated that the fate of the releasable bycatch could be classified into three major species-fate groupings. Two distinct bycatch species assemblages from April through August that …
Airbirds: Adaptative Strategies To The Aerial Lifestyle From A Life History Perspective., Manuel Marin-Aspillaga
Airbirds: Adaptative Strategies To The Aerial Lifestyle From A Life History Perspective., Manuel Marin-Aspillaga
LSU Historical Dissertations and Theses
"Airbirds" are defined as those birds that are adapted to almost constant life on the wing and do not perch, except for breeding and roosting. They use the air as the only medium in which to find and gather food. One taxon meets that definition: the swifts (Apodidae). Foraging zones of airbirds can be segregated in terms of clutch size, commuting foraging distance, nestling period, and nestling feeding rate. This study looked at foraging behavior and nestling diet, incubation patterns and mode of development in cypseloidine swifts, that as a group has extreme life history patterns. In a temperate one-egg …
Phylogeny Of The Characeae (Charophyta) And Biogeography Of Chara (Characeae) Inferred From Ribosomal Rna Genes., Susan T. Meiers
Phylogeny Of The Characeae (Charophyta) And Biogeography Of Chara (Characeae) Inferred From Ribosomal Rna Genes., Susan T. Meiers
LSU Historical Dissertations and Theses
This dissertation examined generic, subsection, and infraspecific aspects of the phylogeny of the Characeae, and biogeography of Chara subsections and Chara haitensis. These relationships were inferred from cladistic and maximum likelihood analyses of sequence data for 18S and ITS regions of nuclear-encoded ribosomal RNA genes. Morphologically-based phylogenetic hypotheses of Wood and Imahori (1965) and Khan and Sarma (1984) concerning the six extant members of Characeae were tested. The analyses supported: monophyly of family Characeae, tribe Chareae, and of Lamprothamnium; placement of Nitellopsis basal to tribe Chareae; and an unresolved relationship between Lamprothamnium and Chara. Neither the hypothesis of Wood and …
Interactive Effects Of Weeds And Defoliating Insects In Soybean (Glycine Max)., Charles Frost Grymes
Interactive Effects Of Weeds And Defoliating Insects In Soybean (Glycine Max)., Charles Frost Grymes
LSU Historical Dissertations and Theses
Field experiments were conducted to evaluate the influence of simulated insect defoliation and full season weed competition on soybean (Glycine max (L.) Merr.) growth and yield. Weeds were johnsongrass (Sorghum halepense (L.) Pers.), common cocklebur (Xanthium strumarium L.), and hemp sesbania (Sesbania exaltata (Raf.) Rybd. ex A. W. Hill) at 15, 3, and 12 plants/6 m of row. Simulated defoliation at R2 and R5 soybean growth stages was accomplished by removal of 0, 1, or 2 leaflets per soybean trifoliate, which approximated 0, 33, and 66% defoliation, respectively. Averaged across defoliation levels and stages, johnsongrass, common cocklebur, and hemp sesbania …
Growth And Mortality Of Fish Larvae In The Northcentral Gulf Of Mexico And Implications To Recruitment., Bruce Henry Comyns
Growth And Mortality Of Fish Larvae In The Northcentral Gulf Of Mexico And Implications To Recruitment., Bruce Henry Comyns
LSU Historical Dissertations and Theses
Extensive plankton collections were taken during September for several years along the northcentral Gulf of Mexico's inner continental shelf. Significant differences in growth rates were found for both vermilion snapper and Atlantic bumper larvae collected at stations where hydrographic conditions were similar, indicating the probable existence of small-scale patchily-distributed feeding conditions. Such variability in growth rates is probably inevitable given the high variability in the observed spatial and temporal distribution of surface chlorophyll a levels, macrozooplankton biomass, copepod abundance, and dispersion of fish larvae. Cruise estimates of mortality coefficients (Z) for larval vermilion snapper, red drum, and Atlantic bumper were …
Seasonal Changes In Gnrh Neurons And Effects Of Dietary Monoamine Precursors On The Hypothalamic-Gonadal Axis In House Sparrows (Passer Domesticus)., Christopher Andrew Meseke
Seasonal Changes In Gnrh Neurons And Effects Of Dietary Monoamine Precursors On The Hypothalamic-Gonadal Axis In House Sparrows (Passer Domesticus)., Christopher Andrew Meseke
LSU Historical Dissertations and Theses
Mechanisms modulating avian seasonal reproduction involve a complex interaction between exogenous environmental information and internal physiologic systems, such as functional changes in the hypothalamic-gonadal axis and changes in the influence of monoaminergic neurotransmitters on hypothalamic neuroendocrine cells. This project was undertaken to describe seasonal changes of the testes and immunoreactive-(ir)-gonadotropin-releasing hormone (GnRH) neurons in House Sparrows in southeastern Louisiana, and to examine the role of monoaminergic neurotransmitters in modulating seasonal reproduction through the use of dietary monoamine precursors. Testicular weights rapidly increased from February to March, peaked from April to July, when the seminiferous tubules were spermatagenically active and filled …
Metamorphosis Of The Hawaiian Stream Goby Sicyopterus Stimpsoni: A Structural, Functional, And Behavioral Analysis., Heiko Lars Schoenfuss
Metamorphosis Of The Hawaiian Stream Goby Sicyopterus Stimpsoni: A Structural, Functional, And Behavioral Analysis., Heiko Lars Schoenfuss
LSU Historical Dissertations and Theses
The endemic goby Sicyopterus stimpsoni is unique among five species of Hawaiian freshwater fishes because it undergoes rapid metamorphosis of cranial structures during postlarval development. These fishes are amphidromous and return after a prolonged stay in the ocean to streams where they are confined to estuaries until completion of cranial restructuring. Within 48 hours after entering fresh water, head width increases significantly, while total length and head length remains unchanged. Weight decreases by approximately 15% during this period. The upper lip enlarges greatly, and the mouth position shifts from terminal to nearly ventral. Shape analysis of radiographs taken from a …
A Search For Biologically Active Phytochemicals From Endemic Plants Of The Southeastern United States., Steven Lynn Robbs
A Search For Biologically Active Phytochemicals From Endemic Plants Of The Southeastern United States., Steven Lynn Robbs
LSU Historical Dissertations and Theses
In an investigation of allelopathy in the Florida scrub, bioassays with terpenes were performed against: Lactuca sativa, Rudbeckia hirta, Leptochloa dubia and Schizachyrium scoparium. Cineole was phytotoxic against Rudbeckia at 17 ppm and Lactuca at 165 ppm. (S)-camphor was phytotoxic to Rudbeckia at 1 ppm, Lactuca at 28 ppm, and Leptochloa and Schizachyrium at 134 ppm. (R)-Camphor, myrtenol and myrtenal were phytotoxic against Rudbeckia at concentrations of 28, 25 and 15 ppm respectively. Farnesol stimulated the germination of Schizachyrium at concentrations up to 50 ppm and at 100 ppm it reduced the radicle length of all test species. Geraniol stimulated …
Factors Controlling The Impacts Of South Louisiana Crude Oil On The Vegetation And Revegetation Of Coastal Wetlands., Qianxin Lin
Factors Controlling The Impacts Of South Louisiana Crude Oil On The Vegetation And Revegetation Of Coastal Wetlands., Qianxin Lin
LSU Historical Dissertations and Theses
The impacts of south Louisiana crude oil on three types of marsh, salt, brackish, and freshwater, dominated by Spartina alterniflora, S. patens, and Sagittaria lancifolia, respectively, were studied in the greenhouse. The influence of a number of factors such as marsh type, plant species, oil dosage, oil coverage, soil composition, leaf surface structure, season and meteorological conditions, on the impact of crude oil to marsh vegetation and revegetation were investigated. Vegetative sensitivity to south Louisiana crude oil increased in the order of S. lancifolia, S. alterniflora, and S. patens. Photosynthetic rates, stem densities, and the regrowth of aboveground biomass for …
Impact Of Insecticides On Predators Of The Soybean Looper, Pseudoplusia Includens (Walker)., Michael Lynn Boyd
Impact Of Insecticides On Predators Of The Soybean Looper, Pseudoplusia Includens (Walker)., Michael Lynn Boyd
LSU Historical Dissertations and Theses
Insecticide toxicity to hemipteran predators (i.e. Geocoris punctipes (Say), Nabis capsiformis Germar, Nabis roseipennis Reuter, and Podisus maculiventris (Say)) was evaluated using three different routes of insecticide exposure (direct contact, indirect insecticide toxicity through consumption of treated prey, and residue uptake). Pirate 3SC$\sp\circler$ (chlorfenapyr) had direct contact toxicity equal to Ambush 2E$\sp\circler$ (permethrin) and Methyl Parathion 4E$\sp\circler$ to most hemipteran predators tested. Exposure to foliage treated with Proclaim 0.16E$\sp\circler$ (emamectin benzoate) usually resulted in lower mortality as compared to Pirate. Condor OF 100F$\sp\circler$ (Bacillus thuringiensis) had the lowest contact toxicity to hemipteran predators of all insecticides tested. Pirate at 0.224 …
Nesting Ecology Of The White-Faced Ibis (Plegadis Chihi) In Southwestern Louisiana., Kathleen Carson Garrett
Nesting Ecology Of The White-Faced Ibis (Plegadis Chihi) In Southwestern Louisiana., Kathleen Carson Garrett
LSU Historical Dissertations and Theses
I studied the nesting ecology of the White-faced Ibis (Plegadis chihi) during the summers of 1994 and 1995 in three colonies in Lacassine National Wildlife Refuge, southwestern Louisiana. Data were collected on colony-site characteristics, chronology (with abundance) of colony formation, reproductive success, and growth and development of ibis nestlings. Small colonies nested in dense buttonbush (Cephalanthus occidentalis) and water willow (Decodon verticillatus) "islands." The largest colony nested in black willows (Salix nigra) (3.2 ha)--a habitat unique to ibis populations in Louisiana--with nests heights up to 7.5 m. Cattle egrets (Bubulcus ibis) (62%) and ibises (36%) were the most abundant species. …
Biological Control Of Pythiaceous Fungi Causing Death Of Longleaf Pine Seedlings During Cold Storage., Xiaoan Sun
Biological Control Of Pythiaceous Fungi Causing Death Of Longleaf Pine Seedlings During Cold Storage., Xiaoan Sun
LSU Historical Dissertations and Theses
Pythium dimorphum Hendrix & Campbell and other Pythium species were determined to be pathogenic fungi that cause the death of longleaf pine seedlings during cold storage. Pathogenicity of these Pythium isolates as determined by infecting newly-germinated slash pine seedlings in vitro was confirmed in field evaluations. An in vitro dual culture screening system was effectively used for selecting Trichoderma isolates capable of killing P. dimorphum. Selected Trichoderma isolates and Gliocladium virens produced volatile and/or non-volatile antibiotics on solid media and in liquid cultures, but antibiotic production could be affected by medium type, pH, and culture age, depending on species or …
Biogeographic, Ecological, And Evolutionary Aspects Of South American Austral Migration, With Special Reference To The Family Tyrannidae., Robert Terry Chesser
Biogeographic, Ecological, And Evolutionary Aspects Of South American Austral Migration, With Special Reference To The Family Tyrannidae., Robert Terry Chesser
LSU Historical Dissertations and Theses
South American austral migrants are bird species that breed in temperate South America in the southern summer and migrate north, towards or into northern South America, for the southern winter. Austral migration is similar to other avian migration systems in many ways, but its uniquely South American locale is reflected geographically by the relatively short-distance migrations of most austral migrants, and taxonomically by the numerical dominance of the suboscine family Tyrannidae (the tyrant-flycatchers), of which more than 70 species migrate. Detailed examination of the distributions of austral migrant flycatchers revealed that each is to some extent unique, but that discernible …
Biotic And Abiotic Factors That Affect The Development And Survival Of Cat Flea (Ctenocephalides Felis (Bouche)) Life Stages., William Joseph Lawrence Jr
Biotic And Abiotic Factors That Affect The Development And Survival Of Cat Flea (Ctenocephalides Felis (Bouche)) Life Stages., William Joseph Lawrence Jr
LSU Historical Dissertations and Theses
Biotic and abiotic factors that affect the development and survival of cat flea (Ctenocephalides felis (Bouche)) life stages were studied. Adult feas maintained on an artificial host system exhibited high rates of mortality when provided with dog hair substrates washed in either hexane or soap and water. Delayed egg production for fleas provided with bovine blood containing Na Citrate concentrations $>$8 mM was observed. Fleas fed with Na Citrate concentrations $\ge$24 mM had an increase in blood consumption and mortality. Certain concentrations of testosterone fed to fleas either in steer blood or in an alternate blood meal were associated …
The Role Of Fecal Pellets In The Flux Of Carbon To The Sea Floor On A River-Influenced Continental Shelf Subject To Hypoxia., Naureen Aziz Qureshi
The Role Of Fecal Pellets In The Flux Of Carbon To The Sea Floor On A River-Influenced Continental Shelf Subject To Hypoxia., Naureen Aziz Qureshi
LSU Historical Dissertations and Theses
The Louisiana continental shelf near the Mississippi and Atchfalaya River deltas is a stratified and highly productive coastal system characterized by the largest hypoxic (dissolved oxygen $<$2 mg l$\sp{-1}$) zone in the western Atlantic Ocean. Carbon export from surface waters in the form of sedimenting zooplankton fecal pellets was examined to determine its importance in the formation and maintenance of oxygen deficiency in the bottom waters. Two sediment traps (5-6 and 15 m) were deployed in 1991 and 1992 in 20 m water depth within an area of chronic and seasonally severe hypoxia. I determined the fecal pellet number and carbon flux, and total carbon flux from the surface waters, the percent primary production exported as fecal pellets, and the potential for fluxed fecal pellet carbon to support bottom water hypoxia. I also quantitatively sampled the water column at discrete depths for fecal pellets and zooplankton to determine potential source organisms and their seasonal, diel and spatial variation. The highest densities of total organisms, copepods and copepod nauplii occurred during March and April (1992), when chlorophyll a concentrations in surface waters were highest, and decreased in summer and fall. The abundance of fecal pellets was positively correlated with total organisms, copepods and copepod nauplii, the likely source of fecal pellets. The fluxes of total particulate material, organic carbon, organic nitrogen, fecal pellet carbon and phytoplankton carbon varied similarly between seasons, and was lowest in summer and highest in spring. The fluxes were greater in 1991 than in 1992. Seasonal variations in fecal pellet number and carbon flux were positively correlated with indicators of high surface water productivity in 1991, but not in 1992. The flux of fecal pellets from surface to bottom waters accounted for 55% of the particulate material exported vertically, exceeded phytoplankton carbon fluxes, and was high enough to deplete the bottom water oxygen reserves in spring. The results support the hypothesis that the development of summer hypoxia is associated with the decomposition of organic matter accumulated in spring primarily by the sedimentation of a phytoplankton bloom via fecal pellets, and not as intact phytoplankton cells.
Behavioral And Chemical Ecology Of Formosan Subterranean Termites, Coptotermes Formosanus Shiraki., Jian Chen
Behavioral And Chemical Ecology Of Formosan Subterranean Termites, Coptotermes Formosanus Shiraki., Jian Chen
LSU Historical Dissertations and Theses
Three colonies of Formosan subterranean termites collected from Lake Charles, Louisiana were not antagonistic towards each other, and three of five colonies collected from New Orleans, Louisiana also showed no aggression. Colonies collected from widely separated parishes, however, often showed antagonistic behavior towards each other. Workers provided food to soldiers from different but amicable colonies whether nestmate soldiers were present or not. Intercolonial mutual grooming also was observed. Furthermore, termites assisted other termites of the same colony or an amicable one in finding food. This assistance in finding food occurred when termites foraged underground or on the surface. Based on …
A Comparison Of The Effects Of Multiple Visual Examples And Nonexamples Versus Prototypical Examples On Science Concept Learning: An Exploratory Study Based Upon The Concept Of Photosynthesis., Eleanor Deane Abrams
A Comparison Of The Effects Of Multiple Visual Examples And Nonexamples Versus Prototypical Examples On Science Concept Learning: An Exploratory Study Based Upon The Concept Of Photosynthesis., Eleanor Deane Abrams
LSU Historical Dissertations and Theses
Two researcher-produced, standard-length videos on photosynthesis (and accompanying ancillary materials) were developed with the input of educators and content experts. The control treatment video script contained the standard number of prototypical examples and graphics based high school textbooks. The experimental treatment video script was based on the theory of conceptual change. Two student focus groups met daily for one week and reviewed portions of the original experimental treatment script for clarity, brevity, and choice and placement of examples and nonexamples. Their suggestions and conceptual change have implications for curriculum design. The main research question of this study was: Do students …