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.

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.

The West Kendall Tree Island site (8DA1081) is a black dirt midden situated on the northeast end of an everglades tree island. The site has been intensely disturbed by excavation pits, particularly on the highest elevations of the site, and becomes increasingly disturbed by a growing Kendall population. Faunal remains recovered in 2008 are examined to reconstruct past ecological habitats, comparing the faunal composition to tree island sites within the Florida Everglades. Based upon identifications, the composition of the site is similar to those of the region, being comprised primarily of freshwater aquatic species and aquatic reptiles, with minimal selection of terrestrial faunal resources. / Includes bibliography. / Thesis (M.A.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Anthropogenic impacts, such as habitat destruction and spread of exotic species, are contributing to the sixth major extinction event in Earth’s history. To develop effective management and conservation plans, it is important to understand the ecological drivers of at-risk populations, assess the ability of a population to adapt to environmental change, and develop research methods for long-term ecosystem monitoring. I used wading birds nesting in the Florida Everglades, USA as a model system to address the challenges of managing and monitoring populations within an ecosystem greatly impacted by anthropogenic activities. Specifically, my project investigated 1) the prey selection of wading bird species, and the role of prey and foraging habitat availability on annual nesting numbers, 2) the ability of using diet change to predict species adaptability to a rapidly changing environment, and 3) the use of sensory data to provide low-cost, long-term monitoring of dynamic wetlands. I found that tricolored herons, snowy egrets, and little blue herons consumed marsh fish larger than those generally available across the landscape. Additionally, number of nests initiated by tricolored herons, snowy egrets, and little blue herons was strongly correlated with the annual densities of large fish available within the Everglades landscape. Conversely, number of nests initiated by wood storks, great egrets, and white ibises was more correlated with the amount of foraging habitat availability across the nesting season. Wood stork diets changed considerably since the 1960’s, consisting of mainly sunfish and exotic fish as opposed to marsh fishes dominant in historical diet studies. Storks also consumed more exotic fish species than they did historically. This diet plasticity and the species’ ability to exploit anthropogenic habitats may be conducive to maintaining population viability as storks experience widespread human-induced changes to their habitat. Sensory-only data models generated complementary results to models that used site-specific field data. Additionally, sensory-only models were able to detect different responses between size classes of fish to the processes that increase their concentrations in drying pools. However, the degree to which sensory variables were able to fit species data was dependent upon the ability of sensors to measure species-specific population drivers and the scale at which sensors can measure environmental change. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

I examined the impact of the exotic, invasive plant Old World climbing fern, Lygodium microphyllum (Cav.) R. Brown, on tree island plant and ant communities in the northern Everglades. I selected 15 tree islands representing four groups: non-Lygodium islands, islands with low levels of Lygodium, islands with high levels of Lygodium, and disturbed islands impacted by people. I used a variety of diversity indices to compare plant and ant data among habitats. The ant communities studied included native and exotic species typical of south Florida. Tree island plant communities were consistent with descriptions from previous studies. Plant species richness decreased with the level of L. microphyllum in the ground and midstory layers. Abundance of native plants decreased with level of L. microphyllum in the ground, midstory, and overstory layers. Lygodium microphyllum did not affect ant communities suggesting that although it negatively impacts plant communities it can provide habitat for ants. / by Camille Darby Carroll. / Thesis (M.S.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

In south Florida, the Greater Everglades ecosystem supports sixteen species of wading birds. Wading birds serve as important indicator species because they are highly mobile, demonstrate flexible habitat selection, and respond quickly to changes in habitat quality. Models that establish habitat relationships from distribution patterns of wading birds can be used to predict changes in habitat quality that may result from restoration and climate change. I developed spatio-temporal species distribution models for the Great Egret, White Ibis, and Wood Stork over a decadal gradient of environmental conditions to identify factors that link habitat availability to habitat use (i.e., habitat selection), habitat use to species abundance, and species abundance (over multiple scales) to nesting effort and success. Hydrological variables (depth, recession rate, days since drydown, reversal, and hydroperiod) over multiple temporal scales and with existing links to wading bird responses were used as proxies for landscape processes that influence prey availability (i.e., resources). In temporal foraging conditions (TFC) models, species demonstrated conditional preferences for resources based on resource levels at differing temporal scales. Wading bird abundance was highest when prey production from optimal periods of wetland inundation was concentrated in shallow depths. Similar responses were observed in spatial foraging conditions (SFC) models predicting spatial occurrence over time, accounting for spatial autocorrelation. The TFC index represents conditions within suitable depths that change daily and reflects patch quality, whereas the SFC index spatially represents suitability of all cells and reflects daily landscape patch abundance. I linked these indices to responses at the nest initiation and nest provisioning breeding phases from 1993-2013. The timing of increases and overall magnitude of resource pulses predicted by the TFC in March and April were strongly linked to breeding responses by all species. Great Egret nesting effort and success were higher with increases in conspecific attraction (i.e., clustering). Wood Stork nesting effort was closely related to timing of concurrently high levels of patch quality (regional scale) and abundance (400-m scale), indicating the importance of a multi-scaled approach. The models helped identify positive and negative changes to multi-annual resource pulses from hydrological restoration and climate change scenarios, respectively. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

In plants, phenotypic plasticity, the ability to morphologically adapt to new or broad environmental conditions, is a consequence of long-term evolutionary genetic processes. Thus, plants adapted to low phosphate (P) environments exhibit only limited plasticity to take advantage of nutrient enrichment, a global phenomenon in terrestrial and aquatic environments. In the face of anthropogenic P-enrichment, low nutrient adapted resident plant species are frequently displaced by species with high morphological and genetic plasticity. However, it remains unclear whether plasticity is systemically expressed across molecular, biochemical, physiological, and morphological processes that ultimately contribute to the root and shoot phenotypes of plants. In this study, we demonstrated high plasticity in root-borne traits of sawgrass (Cladium jamaicense), the dominant plant species of the P-impoverished Everglades, and counter the idea of inflexibility in low P adapted species. However, sawgras s expressed inflexibility in processes contributing to shoot phenotypes, in contrast to cattail, which was highly plastic in shoot characteristics vii in response to P enrichment. In fact, plasticity in cattail shoots is likely a function of its growth response to P that was globally regulated by P-availability at the level of transcription. Plasticity and inflexibility in the growth of both species also diverged in their allocation of P to the chloroplast for growth in cattail versus the vacuole for P storage in sawgrass. In the Everglades, anthropogenic P-enrichment has changed the environment from a P-limited condition, where plasticity in root-borne traits of sawgrass was advantageous, to one of light-competition, where plasticity in shoot-borne traits drives competitive dominance by cattail. / We hypothesize that these shifts in plasticity competitive advantage from root to shoots has been a major driver of cattail expansion in the Everglades ecosystem. Further, this understanding of how natural plant species adapt and shift in response to nutrient availability could also be used a model system to optimize agricultural systems to increase efficiencies in food production and protect low nutrient adapted natural systems from cultural eutrophication. / by James Webb. / Vita. / Thesis (Ph.D.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 200?. Mode of access: World Wide Web.

Fire occurrences in the Everglades have increased since hydrologic alterations began, yet the vulnerability of Everglades peat to combustion during wildfires has yet to be determined. Natural fire regimes help maintain ecosystem functions and services and disruptions of natural disturbance regimes can have detrimental impacts, jeopardizing ecosystem health. Severe peat combustion can destroy native vegetation, alter microtopography, and release large amounts of stored carbon into the atmosphere. To create a better understanding of the mechanistic controls on Everglades ground fires, the soil's physical properties within several sites of Water Conservation Area 3 and how changes in water table affect these physical characteristics were determined. Areas disturbed by hydrologic alterations contain higher mineral content and therefore require lower water content to combust when compared to preserved regions. Changes in water tables have a significant effect on soil moisture and lower water tables drastically increase the vulnerability of a region. / by James Johnson. / Thesis (M.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Understanding the link between indicator species and their environment is imperative to managing and conserving anthropogenically-altered ecosystems. Seasonally-pulsed wetlands are uniquely complex ecosystem where water-level fluctuations shape trophic interactions. Anthropogenic manipulation of water-level fluctuation threatens the integrity of these systems worldwide. Wading birds, a group of species sensitive to landuse changes and fluctuating habitat conditions, serve as important indicators for wetland health. I used wading birds in the Everglades, as a model system to address the challenges of environmental restoration within an ecosystem heavily impacted by anthropogenic activities. Specifically, I 1) identified the nesting response of Great Egret (Ardea alba), White Ibis (Eudocimus albus), and Wood Stork (Mycteria americana) to hydrologically-mediated changes in food availability and 2) quantified spatiotemporal foraging-habitat selection of Great Egrets, White Ibis, and Wood Storks to fluctuating hydrologic conditions. Collectively, model selection results suggest food availability, generated through dynamic hydrological conditions, is a strong predictor of the abundance of nesting birds in a given year. Great egret and white ibis produce the highest nests numbers in years when the frequency of days of rising water is low. Wood stork nest numbers are the highest in years with high prey production coupled with continuous prey availability. My study of resource selection indicated wading birds select foraging sites based on similar hydrologic parameters, but the response varies by species. Wood storks are more likely to forage in shallow cells (< 10 cm) drying with high recession rates (0.5-1.5 cm/day), and long time since last drydown (600 days). White ibises selected foraging cells with relatively shallow water depths (0-15 cm), intermediate recession rates (0.5-1.0 cm/day), and long time since drydown (600 days). Great egrets selected foraging cells with a wider range of water depths (0-20 cm) where recession rates were lower (0.5 cm/day). All species are more likely to forage in cells where water has not increased by more than 3 cm in the previous two weeks. These differences in resource selections correspond to morphological and behavioral differences in the species, whereby wood storks were more constrained hydrologically and would be more affected by water-level manipulation. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Changes in vegetation may influence the quality and quantity of the underlying organic peat soils and have impacts on faunal populations. My goal was to determine whether shifts from native slough communities to invasive cattail in the Florida Everglades could affect peat characteristics that could cascade to impact the dry season survival of crayfish (Procambarus fallax). I contrasted peat soils from native slough and cattail-invaded sites as alternative dry-season burrowing substrates for crayfish. Cattail peat had higher average bulk density and inorganic content within the first ten centimeters of the soil profile. Crayfish showed marginally greater initial burrowing success in slough peat than in cattail peat but survival was equivalent in both peat soils and high overall. Understanding these indirect linkages between vegetation and crayfish populations in the Everglades can provide insight on the consequences of plant invasion on ecosystem trophic dynamics. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection