Ecology and Evolutionary Biology Commons^™

The Role Of Water Motion In Algal Reproduction, Richard Gordon

Electronic Theses and Dissertations

Environmental conditions, such as water motion, can influence fertilization success and spore dispersal in marine algae. Previous studies on fucoid algae showed that gamete release is restricted to, or enhanced by, periods of low water motion. Few other algal taxa have been investigated, however, including species with an alternation of generations. I investigated gamete and spore release in the macroalgae Alaria esculenta and Ulva lactuca, as well as in the diatom Pseudo-nitachia multiseries to determine if water motion is inhibitory or stimulates propagule production and release. I used orbital shakers to simulate water motion; these were interspersed with stationary platforms …

Trichodesmium Spp.: Numerical Studies Of Resource Competition, Carbohydrate Ballasting, And Remote-Sensing Reflectance, Tonya Denise Clayton

OES Theses and Dissertations

In recent years, a new appreciation for the role of diazotrophy in the oceans has emerged. This dissertation reports on three modeling studies designed to investigate ecological processes associated with Trichodesmium spp., the most conspicuous marine diazotroph: (1) characterization of a generalized model Trichodesmium and issues of macronutrient resource competition; (2) carbohydrate ballasting by Trchodesmium and implications for the formation of surface accumulations; and (3) the vertical distribution of Trichodesmium and implications for detection from space.

The first study focuses on issues of nitrogen and phosphorus competition and ecosystem structure. It utilizes a simple ecosystem model that includes dissolved nitrogen …

An Ethical Framework For Interpreting The United States Endangered Species Act, Cathryn M. Elgin

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this study I argue that a holistic approach is better than an individualistic approach for interpreting the United States Endangered Species Act (ESA). I propose that the use of a holistic ethical framework, based on fundamental environmental philosophy, is better in that it more effectively fulfills the ESA's goals of species and ecosystem conservation. Holistic ethics is based on concern for a community as a whole, while individualistic ethics is based on concern for the individual. A holistic approach, I argue, is more beneficial to nature than is an individualistic approach or other non-holistic approaches. I set up basic …

Ecology Of Treeline Whitebark Pine (Pinus Albicaulis) Populations In Central Idaho: Successional Status, Recruitment, And Mortality, And A Spring Temperature Reconstruction From Whitebark Pine Tree Rings, Dana Lee Perkins

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This research investigated the successional status of treeline whitebark pine (Pinus albicaulis) populations on 14 stands in central Idaho and used empirical statistical models to determine the principal factors affecting recruitment and mortality. The longest lived whitebark pines from four additional high-elevation sites were used to develop a tree-ring chronology to reconstruct over 1,000 years of average April-May temperature.

The assessment of stand structures using size-frequency distributions generally provides evidence that treeline whitebark pine populations are currently self-sustaining in areas of low to nonexistent incidence of white pine blister rust (Cronartium ribicola). However the presence of …

The Response Of First And Second Order Streams To Urban Land-Use In Maine, U.S.A., Chandler Morse

Electronic Theses and Dissertations

Physical, chemical, and biological characteristics of streams draining 20 catchments in Maine, U.S.A were compared to determine the influence of increasing urban intensity on stream ecosystem structure. The catchments had varying levels of urban land-use (percentage of the total impervious area within the catchment) ranging from 1-31%. Stream habitat quality, stability, and water quality consistently decreased as the proportion of impervious surface area increased within the catchment. .Indices based on stream benthic macroinvertebrate communities showed even stronger declines as a function of increasing impervious area in the study catchments. Streams draining catchments with levels of impervious surfaces <6% had higher levels of both total and Ephemeroptera + Plecoptera + Trichoptera (EPT) taxonomic richness. With increased levels of urban intensity, benthic macroinvertebrate communities in streams were characterized by decreased numbers of sensitive taxa. Taxa considered to be moderately sensitive to anthropogenic stress (e.g. Acerpenna (Ephemeroptera), Paracapnia …

Effectiveness Of Earthen Escape Ramps In Reducing Big Game Mortality In Utah, Mary L. Hammer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

One-way escape gates and earthen escape ramps are structures used to enable deer to exit the highway right-of-way along fenced roads. I compared the use of one-way escape gates and earthen escape ramps by mule deer on two highways in Utah to determine if deer exhibited a preference for either structure. Results showed that earthen escape ramps were used by mule deer 8-11 times more frequently than one-way gates. Highway mortality data suggest that the installation of the escape ramps likely reduced mortality of mule deer in both study locations, because we could not attribute reductions in mortality to decreased …

Intensification In A Risky Environment: The Case Of Improving Private Grazing Land For Beef Production In Utah, Louise D. Sainsbury

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Utah ranchers commonly face risks to their livelihoods. The objective of this work was to determine if ranchers could make profitable improvements to private land forage given the combined threat of low beef prices, drought, and possible loss of public grazing.

We used linear programming (LINDO) to identify the most profitable solutions for private land investment with an 11-year simulation. Operations were divided into small, medium, and large size classes. Various forage improvements and public permits were options. Two phases of a beef price cycle (peak and trough) and 2 precipitation patterns (wet and drought) were combined as joint favorable …

The Implications Of The Target-Area Hypothesis On The Population Dynamics Of The Spotted Spiny Lobster, Panulirus Guttatus, Denice N. Robertson

Biological Sciences Theses & Dissertations

The target-area hypothesis, based on the theory of island biogeography, predicts that larger islands are more effective at intercepting passive immigrants. Most marine invertebrates have meroplanktonic larvae and open population dynamics, so immigration to populations in isolated benthic habitats is primarily by pelagic larval recruits. Thus, recruitment to isolated habitat “islands” may be more continuous and predictable on large islands than on small ones. Consequently, populations on large islands should not only be larger than those on small islands, but should also have more evenly distributed size structures. These differences in size structure among populations in isolated habitats of differing …

A Comparison Of Phytoplankton Communities In Lake Prince And The Western Branch Reservoir, Suffolk, Virginia, Cara Marie Muscio

Biological Sciences Theses & Dissertations

Lake Prince and the Western Branch Reservoir are two eutrophic bodies of water located in Suffolk, Virginia. Lake Prince and its two small tributaries join the Western branch via a constructed spillway. This lake system is a source of water for the surrounding municipalities, and a recreational area for community citizens. In the past, these bodies of water had repeated incidents of low oxygen and nuisance algal blooms, particularly cyanobacteria species. As a result aerators have been installed in the main body of both Lake Prince and the Western Branch Reservoir. In addition, a pipeline has been installed from North …

Effects Of Human Disturbances On The Behavior Of Dabbling Ducks, Melissa Lynn Pease

Biological Sciences Theses & Dissertations

Disturbance of wintering and migrating birds by human activities can cause birds to expend energy in avoidance of humans and reduces the time available for resting and feeding at a time in the annual cycle when fat deposition and energy conservation are important. Also, human disturbances can effectively cause habitat loss by displacing birds from feeding or resting habitat. Managers of natural resources are increasingly faced with decisions about the types and amounts of public use that should be allowed without lowering the value of the resource for wildlife. In order for managers to make decisions about how to minimize …

Vitellogenin -- A Biomarker Of Exposure To Environmental Estrogens For Mummichog (Fundulus Heteroclitus) From A Creosote-Contaminated Site?, Sara Mirabilio

Dissertations, Theses, and Masters Projects

Vitellogenin (VTG) is widely used as a biomarker for environmental estrogens and reproductive disruption in fish. Vitellogenesis is the process by which yolk is formed. The endpoint is most sensitive in male fish where vitellogenesis is an abnormal process. Research examining effects of environmental mixtures of chemicals (e.g. creosote) on vitellogenesis is limited. This study examines plasma VTG expression in both male and female mummichog, Fundulus heteroclitus, collected from a creosote-contaminated site and two reference sites in lower Chesapeake Bay, USA, and in wild-caught male reference fish exposed in the laboratory to creosote-contaminated sediment. Further, this study uses tissue somatic …

Assessment Of Development Impacts On Coastal Zone: Integrated Approach, Northampton County, Eastern Shore, Virginia, Sarunas Zableckis

Dissertations, Theses, and Masters Projects

No abstract provided.

Heat Shock Protein (Hsp70) Response In The Eastern Oyster, Crassostrea Virginica, Exposed To Various Contaminants (Pahs, Pcbs And Cadmium), Luis A. Cruz Rodriguez

Dissertations, Theses, and Masters Projects

The stress protein response has been proposed as a general indicator of exposure to stress as their expression might integrate overall biological impact and interactions among multiple stressors. as a marker of contaminant effects, a major advantage is the premise of higher sensitivity over other indices such as condition index, scope for growth and survival. Laboratory exposure to suspended field contaminated sediments (SFCS) elicited a stress protein response (HSP70) in the eastern oyster, ( Crassostrea virginica). The stress response probably resulted from the combined effect of various contaminants including PAHs, metals and PCBs. Exposure to 1--2g suspended clay particles spiked …

Application Of The Genetic Algorithm To An Ecological Simulation, William J. Seufzer

Dissertations, Theses, and Masters Projects

A computational framework is built and demonstrated which is capable of testing plant growth strategies. The framework consists of Vgrass, a carbon based simulation model of a single Zostera marina plant, and the genetic algorithm (GA). Vgrass is based on published seagrass models, published photosynthetic data, and general plant physiology information. The model grows individual leaves whose initiation times are based on degree-day intervals. Leaf size is computed and combined with shoot density to compute population self shading. Leaf length is an emergent property since leaf growth is limited by light attenuation caused by self shading. The model is able …

Nursery Delineation, Habitat Utilization, Movements, And Migration Of Juvenile Carcharhinus Plumbeus In Chesapeake Bay, Virginia, United States Of America, R. Dean. Grubbs

Dissertations, Theses, and Masters Projects

Chesapeake Bay is possibly the largest summer nursery for Carcharhinus plumbeus in the western Atlantic. Longline sampling conducted from 1990--1999 was used to delineate this nursery spatially and temporally. Catch data from 83 longline stations sampled throughout the Virginia Chesapeake Bay were analyzed as a function of nine physical and environmental variables to delineate this nursery spatially. Tree-based models determined which variables best discriminated between stations with high and low catches and indicated that complex distribution patterns could be adequately modeled with few variables. The highest abundance of juvenile sharks was predicted where salinity was greater than 20.5 and depth …

The Impact Of Marine Reserves On Exploited Species With Complex Life Histories: A Modeling Study Using The Caribbean Spiny Lobster In Exuma Sound, Bahamas, William T. Stockhausen

Dissertations, Theses, and Masters Projects

Most benthic invertebrates and reef-associated fish undergo a dispersive, planktonic larval stage prior to settlement and metamorphosis into the juvenile and adult stages. In some species, settlement may be decoupled from adult abundance at local spatial scales if hydrodynamic conditions or larval behavior do not promote local retention. Similarly, spatial variability in postsettlement mortality or secondary dispersal by juveniles and adults may decouple spatial patterns of adult abundance from those of settlement. as a consequence, spatial patterns of settlement and adult abundance may be functionally related in a complex fashion. Whether biotic/environmental factors control spatial patterns of abundance may have …