The regular occurrence of hurricane-associated winds has been an important factor in shaping the structure and composition of the forest ecosystems of the Florida Everglades. Forest communities in the Everglades are adapted to hurricane disturbances, but increased frequency and/or intensity of hurricanes may lead to decline or even collapse of these communities. The overall objective of this project is to understand the patterns, pace, and mechanisms of the recovery process to Hurricane Andrew damage in four Everglade forest communities: pinelands, hardwood hammocks, bayhead tree islands, and cypress domes. This study combines long- and short-term field measurements and experimental garden studies to determine how the four woody plant community types recover from hurricane impacts. Most of the community types were adversely affected by storm damage in the short-term (3 years post-hurricane) through altered growth rates and canopy defoliation, however these effects were relatively short lived and were not visible in shifts in species composition after the long-term (20 year) recovery period. Only in the most diverse communities over the long-term there was a delayed mortality in damaged individuals that drove a diversity loss. This loss was not present over the short-term recovery time period. Using individual damage extent and short-term recovery growth rates, I developed a simplified model that accurately predicted surviving individual stem size over long-term recovery periods of Taxodium distichum within cypress domes and select hardwood hammock species. The shadehouse experiments demonstrated the importance of nutrient availability to growth of seedlings of canopy dominants. Recruits of these species responded to changing environmental conditions associated with storm impact through a variety of strategies in accordance with their adaptive traits. Synergistically, the combined parts of this dissertation demonstrate directional community and species-specific shifts that vary over time scales. Storm impacts have the potential to alter community composition and diversity within impacted systems, and in particular the Everglades ecosystem.

The decline of tree islands in the freshwater-Everglades wetland because of hydrologic manipulation, has compromised valuable ecosystem services. Although the role of tree islands in maintaining freshwater quality stems largely from evapotranspiration processes, fundamental questions remain about the effects of different geologic materials on their hydrogeochemical functioning. To reduce this uncertainty, the lithological composition of a set of man-made tree islands was investigated coupled with long-term hydrologic and hydrochemical data. Key results indicate that limestone substrates and peat substrates with elevated proportions of sand, facilitated surface water-groundwater interactions and mineral dissolution. However, limestone-based islands were more effective in lowering the water table and concentrating solutes in response to evapotranspiration during low surface water stages. Additionally, the peat substrate of an island with low sand content favored the thermodynamic conditions for calcite accumulation in the phreatic zone, while phosphorus concentrations in the groundwater were associated with the breakdown of organic matter.

Bottlenose dolphins (Tursiops truncatus) are large-bodied predators that are locally abundant in the coastal Everglades. Because of their potential to exert strong top-down effects on their communities, it is important to understand how spatiotemporal variation in biotic and abiotic factors affects the abundance and behavior of dolphins. This study combined two years of transect surveys with photographic identification methods to assess spatiotemporal variation in the abundance and group sizes of bottlenose dolphins across four large regions of the coastal Everglades including the Shark and Harney Rivers, Whitewater Bay, and coastal oceans of the Gulf of Mexico and Florida Bay. Dolphin abundance was similar across wet and dry seasons, except in river habitats where abundances were higher during the dry season. Group sizes were largest in Florida Bay and open water. Dolphins may be relatively resilient to abiotic changes in the coastal Everglades, with the possible exception of river habitats.

Coastal environments can be highly susceptible to environmental changes caused by anthropogenic pressures and natural events. Both anthropogenic and natural perturbations may directly affect the amount and the quality of water flowing through the ecosystem, both in the surface and subsurface and can subsequently, alter ecological communities and functions. The Florida Everglades and the Sian Ka’an Biosphere Reserve (Mexico) are two large ecosystems with an extensive coastal mangrove ecotone that represent a historically altered and pristine environment, respectively. Rising sea levels, climate change, increased water demand, and salt water intrusion are growing concerns in these regions and underlies the need for a better understanding of the present conditions. The goal of my research was to better understand various ecohydrological, environmental, and hydrogeochemical interactions and relationships in carbonate mangrove wetlands. A combination of aqueous geochemical analyses and visible and near-infrared reflectance data were employed to explore relationships between surface and subsurface water chemistry and spectral biophysical stress in mangroves. Optical satellite imagery and field collected meteorological data were used to estimate surface energy and evapotranspiration and measure variability associated with hurricanes and restoration efforts. Furthermore, major ionic and nutrient concentrations, and stable isotopes of hydrogen and oxygen were used to distinguish water sources and infer coastal groundwater discharge by applying the data to a combined principal component analysis-end member mixing model. Spectral reflectance measured at the field and satellite scales were successfully used to estimate surface and subsurface water chemistry and model chloride concentrations along the southern Everglades. Satellite imagery indicated that mangrove sites that have less tidal flushing and hydrogeomorphic heterogeneity tend to have more variable evapotranspiration and soil heat flux in response to storms and restoration. Lastly, water chemistry and multivariate analyses indicated two distinct fresh groundwater sources that discharge to the phosphorus-limited estuaries and bays of the Sian Ka’an Biopshere Reserve; and that coastal groundwater discharge was an important source for phosphorus. The results of the study give us a better understanding of the ecohydrological and hydrogeological processes in carbonate mangrove environments that can be then be extrapolated to similar coastal ecosystems in the Caribbean.

The Greater Everglades system imparts vital ecosystem services (ES) to South Florida residents including high quality drinking water supplies and a habitat for threatened and endangered species. As a result of the altered Everglades system and regional dynamics, restoration may either improve the provision of these services or impose a tradeoff between enhanced environmental goods and services and competing societal demands. The current study aims at understanding public preferences for restoration and generating willingness to pay (WTP) values for restored ES through the implementation of a discrete choice experiment. A previous study (Milon et al., 1999) generated WTP values amongst Floridians of up to $3.42 -$4.07 billion for full restoration over a 10-year period. We have collected data from 2,905 respondents taken from two samples who participated in an online survey designed to elicit the WTP values for selected ecological and social attributes included in the earlier study (Milon et al. 1999). We estimate that the Florida general public is willing to pay up to $854.1- $954.1 million over 10 years to avoid restrictions on their water usage and up to $90.8- $183.7 million over 10 years to restore the hydrological flow within the Water Conservation Area.

Mangroves are the dominant vegetation in Everglades estuarine environment and are known to contain polyphenols such as tannins, which present similar fluorescence properties as some amino acid fluorophores. In the present study, gas chromatography–mass spectrometry (GC/MS) was used to quantify gallic acid, which is a normal monomer of polyphenols. The quantitative GC/MS analytical method was developed using gallic acid and tannic acid standards to quantify the false ‘protein-like’ fluorescence in DOM. The present study also compared the optical properties, reactive species (RS) production and radical scavenging ability of DOM from different regions of the Everglades and a correlation was observed between DOM composition and its photo-productivity. In general, the reactive species quantum yield decreased with increased DOM redox potential. The RS formation rates were controlled by the DOC and CDOM abundace. Normalized RS formation rates were shown to be influenced by DOM aromaticity and molecular weight characteristics

Hydroscape structure can play a critical role in animal behavior, abundance, and community structure dynamics. Hydroscape configuration can be dynamic and can change quickly in ephemeral systems. However, ephemeral freshwater wetlands are among the most impacted systems in the world and restoration efforts often rely on incomplete information when establishing management objectives. Further understanding how alterations in hydroscape structure in dynamic systems affect animals is critical for conservation and management success. To determine impacts that changing hydroscape conditions can have on consumers in freshwater wetlands, I examined the effects of a large-scale physical model on fish behavior, abundance, and community structure. The physical model incorporated the restoration of sheetflow, canal-fill treatments, and the removal of a decades-old levee that divided two water management areas in the central Everglades. Small fishes modified directional movement behaviors and speed of movement before and after alterations took place, though behavioral responses varied widely by species. Density and community structure of small fishes did change as a function of canal-fill and levee removal treatments. Behaviors of large fishes were also affected by hydroscape alterations, as well as hydroscape configuration beyond the limited footprint of the physical model. Large fish abundance was altered by hydroscape alteration, particularly among certain species. Composition of the large fish community changed before and after hydroscape alteration, though magnitude of responses were site-specific. Effects of hydroscape structure proximity on trophic dynamics were examined using exclosure cages that excluded large predators but allowed access for small consumers. Exclosures were stratified according to proximity to a deep-water canal. Predator avoidance behaviors in small consumers were limited but present. Differences in behavior between sites may also be caused by differences in structure across sites and limited differences in nutrient quality. Behavioral, population, and community responses to hydroscape alteration can be valuable metrics to assess the success of hydroscape restoration. While results can vary across individuals, species, and sampling sites, effects can still be detected even at the scale of the hydroscape. My research has detailed the potential effects of restoration plans across the greater Everglades and can be extended to other ephemeral wetland restoration programs.

The Florida Everglades has a long history of anthropogenic changes which have impacted the quantity and quality of water entering the system. Since the construction of Tamiami Trail in the 1920's, overland flow to the Florida Everglades has decreased significantly, impacting ecosystems from the wetlands to the estuary. The MIKE Marsh Model of Everglades National Park (M3ENP) is a numerical model, which simulates Everglades National Park (ENP) hydrology using MIKE SHE/MIKE 11software. This model has been developed to determine the parameters that effect Everglades hydrology and understand the impact of specific flow changes on the hydrology of the system. As part of the effort to return flows to the historical levels, several changes to the existing water management infrastructure have been implemented or are in the design phase. Bridge construction scenarios were programed into the M3ENP model to review the effect of these structural changes and evaluate the potential impacts on water levels and hydroperiods in the receiving Northeast Shark Slough ecosystem. These scenarios have shown critical water level increases in an area which has been in decline due to low water levels. Results from this work may help guide future decisions for restoration designs. Excess phosphorus entering Everglades National Park in South Florida may promote the growth of more phosphorus-opportunistic species and alter the food chain from the bottom up. Two phosphorus transport methods were developed into the M3ENP hydrodynamic model to determine the factors affecting phosphorus transport and the impact of bridge construction on water quality. Results showed that while phosphorus concentrations in surface waters decreased overall, some areas within ENP interior may experience an increase in phosphorus loading which the addition of bridges to Tamiami Trail. Finally, phosphorus data and modeled water level data was used to evaluate the spectral response of Everglades vegetation to increasing phosphorus availability using Landsat imagery.

Dissolved organic matter (DOM) is one of the largest carbon reservoirs on this planet and is present in aquatic environments as a highly complex mixture of organic compounds. The Florida coastal Everglades (FCE) is one of the largest wetlands in the world. DOM in this system is an important biogeochemical component as most of the nitrogen (N) and phosphorous (P) are in organic forms. Achieving a better understanding of DOM dynamics in large coastal wetlands is critical, and a particularly important issue in the context of Everglades restoration. In this work, the environmental dynamics of surface water DOM on spatial and temporal scales was investigated. In addition, photo- and bio-reactivity of this DOM was determined, surface-to-groundwater exchange of DOM was investigated, and the size distribution of freshwater DOM in Everglades was assessed. The data show that DOM dynamics in this ecosystem are controlled by both hydrological and ecological drivers and are clearly different on spatial scales and variable seasonally. The DOM reactivity data, modeled with a multi-pool first order degradation kinetics model, found that fluorescent DOM in FCE is generally photo-reactive and bio-refractory. Yet the sequential degradation proved a “priming effect” of sunlight on the bacterial uptake and reworking of this subtropical wetland DOM. Interestingly, specific PARAFAC components were found to have different photo- and bio-degradation rates, suggesting a highly heterogeneous nature of fluorophores associated with the DOM. Surface-to-groundwater exchange of DOM was observed in different regions of the system, and compositional differences were associated with source and photo-reactivity. Lastly, the high degree of heterogeneity of DOM associated fluorophores suggested based on the degradation studies was confirmed through the EEM-PARAFAC analysis of DOM along a molecular size continuum, suggesting that the fluorescence characteristics of DOM are highly controlled by different size fractions and as such can exhibit significant differences in reactivity.

An integrated surface-subsurface hydrological model of Everglades National Park (ENP) was developed using MIKE SHE and MIKE 11 modeling software. The model has a resolution of 400 meters, covers approximately 1050 square miles of ENP, includes 110 miles of drainage canals with a variety of hydraulic structures, and processes hydrological information, such as evapotranspiration, precipitation, groundwater levels, canal discharges and levels, and operational schedules. Calibration was based on time series and probability of exceedance for water levels and discharges in the years 1987 through 1997. Model verification was then completed for the period of 1998 through 2005. Parameter sensitivity in uncertainty analysis showed that the model was most sensitive to the hydraulic conductivity of the regional Surficial Aquifer System, the Manning's roughness coefficient, and the leakage coefficient, which defines the canal-subsurface interaction. The model offers an enhanced predictive capability, compared to other models currently available, to simulate the flow regime in ENP and to forecast the impact of topography, water flows, and modifying operation schedules.