• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1441
  • 41
  • 23
  • 5
  • 4
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 2793
  • 1234
  • 1019
  • 965
  • 903
  • 884
  • 677
  • 514
  • 435
  • 408
  • 363
  • 292
  • 283
  • 245
  • 238
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
641

Postglacial expansion of Rhizophora Mangle l. In the Caribbean Sea and Florida

Unknown Date (has links)
The Last Glacial Maximum (LGM) was a period of massive range contraction for numerous taxa, including the water-dispersed mangrove species, Rhizophora mangle L. Following the LGM, R. mangle expanded poleward via propagule transport by ocean currents. In this study, we use microsatellite loci to characterize the genetic structure of nine R. mangle populations and compare potential expansion pathways that resulted in the colonization of the Florida peninsula and Caribbean islands. Results show comparatively greater genetic connectivity between the Caribbean mainland and Florida, a similar pattern between West Africa and Caribbean islands, and substantial admixture on the island of San Salvador, the Bahamas. We conclude that Florida and Caribbean island R. mangle populations were likely recolonized via different expansion pathways. Estimates of recent migration rates are low and populations are structured into three regions (Caribbean mainland, Caribbean islands, Florida). These findings provide insight for future management and conservation initiatives. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
642

Monitoring seasonal and annual changes in the mesozooplankton community of the Indian River Lagoon, Florida

Unknown Date (has links)
In estuaries, like the Indian River Lagoon, mesozooplankton have a vital role in the food web by connecting trophic levels. In this study, mesozooplankton abundance and species composition were monitored weekly on the incoming and outgoing tides from September 2006 to May 2009. For the incoming tide, the mean abundance was 2298.2 mesozooplankton/m3 (+/-325.2), and for the outgoing tide the mean abundance was 1180.0 mesozooplankton/m3 (+/-153.1). The mesozooplankton abundance on the incoming tide was significantly greater than on the outgoing tide. The most abundant type of mesozooplankton was the copepod Acartia tonsa, representing 35.0% and 52.1% of the individuals on the incoming and outgoing tides respectively. Mesozooplankton abundance values were compared with environmental data obtained from the South Florida Water Management District. The strongest positive correlation was found between chlorophyll a concentrations and A. tonsa abundance, likely due to phytoplankton being the primary food source for A. tonsa. / by Miranda Hoover Kerr. / Thesis (M.S.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.
643

Salinity Assessment, Change, and Impact on Plant Stress / Canopy Water Content (CWC) in Florida Bay using Remote Sensing and GIS

Unknown Date (has links)
Human activities in the past century have caused a variety of environmental problems in South Florida. In 2000, Congress authorized the Comprehensive Everglades Restoration Plan (CERP), a $10.5-billion mission to restore the South Florida ecosystem. Environmental projects in CERP require salinity monitoring in Florida Bay to provide measures of the effects of restoration on the Everglades ecosystem. However current salinity monitoring cannot cover large areas and is costly, time-consuming, and laborintensive. The purpose of this dissertation is to model salinity, detect salinity changes, and evaluate the impact of salinity in Florida Bay using remote sensing and geospatial information sciences (GIS) techniques. The specific objectives are to: 1) examine the capability of Landsat multispectral imagery for salinity modeling and monitoring; 2) detect salinity changes by building a series of salinity maps using archived Landsat images; and 3) assess the capability of spectroscopy techniques in characterizing plant stress / canopy water content (CWC) with varying salinity, sea level rise (SLR), and nutrient levels. Geographic weighted regression (GWR) models created using the first three imagery components with atmospheric and sun glint corrections proved to be more correlated (R^2 = 0.458) to salinity data versus ordinary least squares (OLS) regression models (R^2 = 0.158) and therefore GWR was the ideal regression model for continued Florida Bay salinity assessment. J. roemerianus was also examined to assess the coastal Everglades where salinity modeling is important to the water-land interface. Multivariate greenhouse studies determined the impact of nutrients to be inconsequential but increases in salinity and sea level rise both negatively affected J. roemerianus. Field spectroscopic data was then used to ascertain correlations between CWC and reflectance spectra using spectral indices and derivative analysis. It was determined that established spectral indices (max R^2 = 0.195) and continuum removal (max R^2= 0.331) were not significantly correlated to CWC but derivative analysis showed a higher correlation (R^2 = 0.515 using the first derivative at 948.5 nm). These models can be input into future imagery to predict the salinity of the South Florida water ecosystem. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection
644

Population distribution, habitat selection, and life history of the slough crayfish (Procambarus fallax) in the ridge-slough landscape of the central Everglades

Unknown Date (has links)
Understanding where and why organisms are distributed in the environment are central themes in ecology. Animals live in environments in which they are subject to competing demands, such as the need to forage, to find mates, to reproduce, and to avoid predation. Optimal habitats for these various activities are usually distributed heterogeneously in the landscape and may vary both spatially and temporally, causing animals to adjust their locations in space and time to balance these conflicting demands. In this dissertation, I outline three studies of Procambarus fallax in the ridge-slough landscape of Water conservation Area 3A (WCS-3A). The first section outlines an observational sampling study of crayfish population distribution in a four hectare plot, where I statistically model the density distribution at two spatial scales. ... Secondly, I use radio telemetry to study individual adult crayfish movements at two study sites and evaluate habitat selection using Resource Selection Functions. In the third section, I test the habitat selection theory, ideal free distribution, by assessing performance measures (growth and mortality) of crayfish in the two major vegetation types in a late wet season (November 2007) and early wet season (August 2009). / by Craig van der Heiden. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliographical references at the end of each chapter. / Mode of access: World Wide Web. / System requirements: Adobe Reader.
645

Limitations on macroinvertebrate populations in South Florida weltands

Unknown Date (has links)
It can be difficult to disentangle the factors that determine population success in freshwater systems, particularly for organisms with disturbance-resistant life stages like aquatic invertebrates. Nevertheless, the effects of environmental variation and habitat structure on animal population success in wetlands are important for understanding both trophic interactions and biodiversity. I performed two experiments to determine the factors limiting crayfish (Procambarus fallax) and dragonfly (Family: Libellulidae) populations in wetland environments. A simulation of a dry-disturbance and subsequent sunfish (Family: Centrarchidae) re-colonization revealed that crayfish populations are sensitive to sunfish, while dragonfly naiads seemed to be limited by other drying-related factors. A second manipulation revealed that small-bodied fishes and habitat structure (submerged vegetation) shaped dragonfly communities primarily through postcolonization processes. / by Natalie Knorp. / Thesis (M.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.
646

Mollusks of the late Pleistocene oèolitic facies of the Miami Limestone in the Miami-Dade County, South Florida

Unknown Date (has links)
The oèolitic limestone that makes up the bedrock of Miami-Dade and parts of Broward County, Florida, is a relatively well studied formation, with poorly studied fossil content. No published systematic record of Pleistocene fossils in the Miami Limestone is available. Besides the basic knowledge of taxonomy and biodiversity of the mollusks, comparison with extant assemblages can yield important information about the biodiversity changes in southern Florida during the past ~130,000 years. Preliminary surveys of several localities, both previously described and new, within the Dade County yielded a record of diverse mollusks from over 28 families, 34 genera and 40 species. The preliminary findings of molluscan fossils have led to a new, unstudied and unpublished fossil locality with the second discovery of a possible Strombus costatus in the Miami Limestone. Miami Limestone fossils are being compared to recent South Florida mollusks indicating patterns of local diversification and extinction related to the minor changes in sea level and disappearance of certain habitats such as the rocky shore substrates that Cittarium pica once thrived on. / by Heather M. D'Antonio. / Thesis (M.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.
647

The community college baccalaureate: a study of capital costs in Florida

Unknown Date (has links)
This study focused on the capital costs of the community college baccalaureate (CCB) institutions established in the Florida College System (FCS) from 2001 to 2010. This period spanned the entire history to date of the Florida CCB. The data analyzed included selected institutional, financial, and baccalaureate characteristics of the Florida CCBs and for comparison included corresponding institutional and financial characteristics for the non-CCB institutions in the FCS. The data analysis investigated the relationships between these characteristics and the baccalaureate capital costs reported by Florida's CCB colleges. From these relationships, the historic average of the baccalaureate start-up capital cost was derived. In addition, the total baccalaureate capital cost for the system and for each Florida CCB college was also determined. As part of the process of conducting this study, a number of additional relationships between CCB and non-CCB institutions were explored, reported, and described. / by E. Allen Bottorff, II. / Thesis (Ph.D.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.
648

A cost-effectiveness analysis of two community college baccalaureate programs in Florida: an exploratory study

Unknown Date (has links)
The purpose of this case study was to determine which, if any, alternative in delivering baccalaureate programs in the state of Florida was the most cost-effective one. This exploratory study focused on gaining an understanding of the cost effectiveness of two baccalaureate programs offered at a Florida community college to two like programs at a Florida university using qualitative and quantitative methodologies. The researcher interviewed five community college and three State Department of Education administrators during the Fall of 2007 and analyzed expenditure and effectiveness data from 2003-04 through 2006-07 to determine the cost effectiveness for the programs at each institution. The study revealed that the university and community college programs were equally effective as measured by student graduation and test scores. The community college baccalaureate programs were more cost effective, however, using a formula of per-student state funding combined with student cost. Th e lower per-student funding and student tuition charged resulted in the community college baccalaureate being a less expensive alternative of offering baccalaureate degrees to the state and the students. Using Henry Levin's ingredients model of measuring cost effectiveness, the quantitative analysis of the study revealed that that the university programs were more cost effective in the early years, but the differences diminished over time. Using Levin's model for comparison, the researcher concluded that increased growth in the enrollment of the programs combined with the implementation of effectiveness measures comparable to those of the university would render baccalaureate programs at the community colleges more cost effective. / Conclusions based on the formula of state and student cost were based on factual data, while conclusions based on Levin's ingredients model were based on assumptions and estimates using a weighting factor along with an indirect cost rate for Proxim University. The study identified factors other than the cost effectiveness that could make the community college baccalaureate a more attractive alternative and concluded with recommendations for practice, policy, and future research. Differences in state and local laws, or economic, geographical, and environmental differences combined with the nature of this exploratory case study limit the generalizability of the results of this study. / by Edwin P. Bemmel. / Vita. / Thesis (Ph.D.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, FL : 2008 Mode of access: World Wide Web.
649

Hierarchical resource selection and movement of two wading bird species with divergent foraging strategies in the Everglades

Unknown Date (has links)
Seasonal variation in food availability is one of the primary limitations to avian populations, particularly during the breeding season. However, the behavioral responses between species may differ based on foraging strategies. I examined the influence of food availability on landscape-level habitat selection, patch-level habitat selection, and movements of two wading bird species with divergent foraging strategies, the Great Egret and White Ibis. On a landscape scale, there appeared to be a relationship among resource availability, the temporal scale of the independent variable, and whether the response was similar or different between species. At the patch level, results demonstrated a relationship between resource availability and the spatial scale of the independent variables selected by birds. Species movements were consistent with the differing strategies. This study is the first to make the link between landscape hydrology patterns, prey availability, and responses in wading bird habitat selection at multiple spatial scales. / by James M. Beerens. / Thesis (M.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.
650

Toxicity and availability of copper and zinc to queen conch: implications for larval recruitment in the Florida Keys

Unknown Date (has links)
by Amber L. Garr. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web. / The presence of heavy metals and other pollutants is detrimental to marine ecosystems. The queen conch, once an important fisheries species in the Florida Keys, has not sufficiently recovered after a 25-year fishery closure. Research has shown high levels of copper and zinc in the gonads and digestive glands of adult conch found in the nearshore waters. Four sites relevant to queen conch larval recruitment were tested in 2010 for the presence of copper and zinc in the water, phytoplankton, sediment, and seagrass epiphytes over seven months. Both metals were detected in all sample types and no seasonal or geographical differences were detected. Surface water concentrations from the field were used to conduct acute and chronic toxicity tests on various ages of queen conch larvae and their phytoplankton food source. When zinc concentrations (0-40 (So(Bg/L) similar to those measured in situ were used, there was no significant impact on conch larval survival although some velar lobe de velopment was impaired. However, field concentrations of copper (0-15 (So(Bg/L), which often surpassed water quality standards, negatively impacted growth, survival, and development of the larvae. Chronic exposure to copper, through the water and food, disrupted the metamorphic success of competent larvae and decreased post-metamorphosis survival. Exposure to copper at later life stages increased mortality, suggesting that heavy metals have a negative effect on larval recruitment in localized areas of the Florida Keys. Structural equation modeling revealed that copper and zinc are moving through the systems differently and are best represented by two different models.

Page generated in 0.0482 seconds