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- Title
- CHANGES IN PHYSICAL PROPERTIES OF THE PEAT SOIL MATRIX ACROSS A SALINITY GRADIENT IN THE EVERGLADES: IMPLICATIONS FOR ACCELERATING PEAT COLLAPSE DURING SEA LEVEL RISE.
- Creator
- Florey, Maxwell, Comas, Xavier, Florida Atlantic University, Department of Geosciences, Charles E. Schmidt College of Science
- Abstract/Description
-
Peatlands are areas with an accumulated layer of peat soil that are considered global stores of carbon, acting as a net sink of carbon dioxide and a net source of methane. Recent studies in coastal peatlands have shown how that a rise in sea level may contribute to the degradation of peat soils due to the inland progression of the saltwater interface, which may result in physical changes within the peat matrix that may eventually result in peat collapse. For example, earlier studies in boreal...
Show morePeatlands are areas with an accumulated layer of peat soil that are considered global stores of carbon, acting as a net sink of carbon dioxide and a net source of methane. Recent studies in coastal peatlands have shown how that a rise in sea level may contribute to the degradation of peat soils due to the inland progression of the saltwater interface, which may result in physical changes within the peat matrix that may eventually result in peat collapse. For example, earlier studies in boreal peat soils described the effect of pore dilation as a result of increased salinity in peat soils, while recent studies in Everglades peat soils showed specific salinity thresholds that may represent a permanent loss of the structural integrity of the peat matrix that may represent early stages of peat collapse. While most of these previous efforts have focused on drivers, recent work has also explored conceptual models to better understand the mechanisms inducing peat collapse. However, few datasets exists that consistently compare differences in physical properties under different in‐situ salinity conditions. In this study differences in the physical properties of peat soils across a salinity gradient along the western edge of Big Cypress National Preserve are investigated to test how differences in salinity may induce physical changes in the soil matrix. The physical properties targeted for this study include porosity, hydraulic conductivity, and carbon content. Measurements are conducted at the laboratory scale using peat cores and monoliths collected at selected locations to investigate: 1) how overall soil physical properties change spatially over a salinity gradient at the km scale moving from permanently saline to freshwater conditions; and 2) how physical properties change spatially at specific sites as dependant on vegetation boundaries and proximity to collapsed soils. This study has implications for better understanding the potential relation between physical changes of the soil matrix and the phenomena of peat collapse in the Everglades as saltwater intrusion progresses inward and alters freshwater ecosystems. Furthermore, a better mechanistic understanding of the peat collapse phenomenon can potentially help mitigate its occurrence.
Show less - Date Issued
- 2021
- PURL
- http://purl.flvc.org/fau/fd/FA00013809
- Subject Headings
- Peat soils, Salinity, Sea level, Big Cypress National Preserve (Fla.), Everglades (Fla.)
- Format
- Document (PDF)
- Title
- EFFECTS OF SALTWATER INTRUSION ON THE COMPRESSIBILITY BEHAVIOR OF THE EVERGLADES SOILS.
- Creator
- Ribeiro, Camila, Sobhan, Khaled, Florida Atlantic University, Department of Civil, Environmental and Geomatics Engineering, College of Engineering and Computer Science
- Abstract/Description
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The Florida Everglades is considered as a vulnerable wetland composed primary of organic rich peat soils, experiencing saltwater intrusion. Impact of increasing salinity on the strength and deformation properties of peat is unknown. A laboratory study was undertaken to evaluate how the growing salinity level due to sea level rise may alter the compressibility behavior of the Everglades soils. Sixteen 1-dimensional oedometer tests were conducted on undisturbed Everglades peat soils in two...
Show moreThe Florida Everglades is considered as a vulnerable wetland composed primary of organic rich peat soils, experiencing saltwater intrusion. Impact of increasing salinity on the strength and deformation properties of peat is unknown. A laboratory study was undertaken to evaluate how the growing salinity level due to sea level rise may alter the compressibility behavior of the Everglades soils. Sixteen 1-dimensional oedometer tests were conducted on undisturbed Everglades peat soils in two phases. Phase I included samples from Site 1 (saltwater) and Site 3 (freshwater) without any salinity addition. Phase II consisted of soil from Site 3 (freshwater) saturated in six different levels of salinity artificially added to the samples. Compressibility properties investigated in this study include compression index (Cc), coefficient of consolidation (Cv), hydraulic conductivity (K), and the Ca/Cc ratio. In general, it was observed that the increase in salinity beyond a threshold value tends to increase the soil compressibility properties, indicating a possible reduction in soil stability with saltwater intrusion.
Show less - Date Issued
- 2021
- PURL
- http://purl.flvc.org/fau/fd/FA00013783
- Subject Headings
- Everglades (Fla.), Peat soils, Saltwater encroachment, Compressibility
- Format
- Document (PDF)
- Title
- EFFECTS OF WATER FLOW ON A WETLAND MACROINVERTEBRATE COMMUNITY.
- Creator
- Hansen, Chris, Dorn, Nathan, Florida Atlantic University, Department of Environmental Sciences, Charles E. Schmidt College of Science
- Abstract/Description
-
Macroinvertebrates make up a large fraction of secondary production in wetlands and are strongly influenced by hydrologic alterations. However, little is known of the effect flow has on macroinvertebrate production and community composition in wetlands. Reintroducing measurable water velocities (1-5 cm/s) to the oligotrophic (phosphoruslimited) Everglades has the potential to affect macroinvertebrate production and community structure by increasing the supply of phosphorus (P) to periphyton,...
Show moreMacroinvertebrates make up a large fraction of secondary production in wetlands and are strongly influenced by hydrologic alterations. However, little is known of the effect flow has on macroinvertebrate production and community composition in wetlands. Reintroducing measurable water velocities (1-5 cm/s) to the oligotrophic (phosphoruslimited) Everglades has the potential to affect macroinvertebrate production and community structure by increasing the supply of phosphorus (P) to periphyton, changing basal food quality, and physically altering the habitat. In Chapter 2, I investigated the potential effects of flow-mediated nutrient-loading on the growth rate of herbivorous grazers, apple snails (Pomacea maculata), by growing periphyton on standard substrates, in four sloughs within a landscape-scale flow addition experiment; two sloughs received elevated flow velocities (2.9-5.2 cm/s) and two control sloughs (0.3-0.4 cm/s). Snails fed periphyton from the flowing sloughs gained more than 3.7-fold greater total mass than snails fed periphyton from the control sloughs. The highest velocity slough produced the greatest snail growth. Snail growth was correlated with P accumulation and C:P ratios in the periphyton. Water column nutrients were low and the water column TP differences among sloughs could not fully explain differences in periphyton nutrients or snail growth. Increasing flow above background conditions by as little as 2.4 cm/s in this oligotrophic wetland altered periphyton food quality by flow loading, which subsequently increased growth rates of primary consumers. In Chapter 3, I investigated potential changes in macroinvertebrate standing stock biomass and community composition caused by flow by conducting two sweep net surveys. Surveys were conducted within two groups of sloughs, flow sloughs (6 sloughs) and control sloughs (12 sloughs), within the same landscape-scale flow addition experiment as the growth experiment. Surveys were conducted from January to March in 2018 and 2021. Biomass was compared between the flow sloughs and control sloughs using generalized linear models. Community composition was analyzed at the slough level using Bray-Curtis similarity. Biomass of macroinvertebrates was similar among transects in 2018 but higher in the flow sloughs in 2021 with the highest biomasses further from the L67A (velocities <2cm/s). The two highest flowing sloughs (typically >3cm/s) had a different community composition from the other 16 sloughs in both 2018 and 2021 with a predator resistant non-native snail appearing in 2021. The results of the surveys show an increase in macroinvertebrate production in the flow sloughs possibly related to increased nutritional value of food, however, with higher biomass further from the L67A and the invasion of a predator resistant snail at the high flow sloughs, it also appears that there is increased top-down pressure on the macroinvertebrates at the sloughs closer to the L67A (were cover from predation has been reduced). The overall results of these studies indicate flow produces more nutritional food for herbivorous macroinvertebrates and increases standing stock biomass but can change the community composition when periphyton cover is reduced.
Show less - Date Issued
- 2021
- PURL
- http://purl.flvc.org/fau/fd/FA00013873
- Subject Headings
- Wetland ecology, Everglades (Fla.), Invertebrate communities
- Format
- Document (PDF)
- Title
- Increasing Integrity in Sea-Level Rise Impact Assessment on Florida’s Coastal Everglades.
- Creator
- Cooper, Hannah M., Zhang, Caiyun, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
- Abstract/Description
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Over drainage due to water management practices, abundance of native and rare species, and low-lying topography makes the coastal Everglades especially vulnerable to Sea-Level Rise (SLR). Water depths have shown to have a significant relationship to vegetation community composition and organization while also playing a crucial role in vegetation health throughout the Everglades. Modeling potential habitat change and loss caused by increased water depths due to SLR requires better vertical...
Show moreOver drainage due to water management practices, abundance of native and rare species, and low-lying topography makes the coastal Everglades especially vulnerable to Sea-Level Rise (SLR). Water depths have shown to have a significant relationship to vegetation community composition and organization while also playing a crucial role in vegetation health throughout the Everglades. Modeling potential habitat change and loss caused by increased water depths due to SLR requires better vertical Root Mean Square Error (RMSE) and resolution Digital Elevation Models (DEMs) and Water Table Elevation Models (WTEMs). In this study, an object-based machine learning approach was developed to correct LiDAR elevation data by integrating LiDAR point data, aerial imagery, Real Time Kinematic (RTK)-Global Positioning Systems (GPS) and total station survey data. Four machine learning modeling techniques were compared with the commonly used bias-corrected technique, including Random Forest (RF), Support Vector Machine (SVM), k-Nearest Neighbor (k-NN), and Artificial Neural Network (ANN). The k-NN and RF models produced the best predictions for the Nine Mile and Flamingo study areas (RMSE = 0.08 m and 0.10 m, respectively). This study also examined four interpolation-based methods along with the RF, SVM and k-NN machine learning techniques for generating WTEMs. The RF models achieved the best results for the dry season (RMSE = 0.06 m) and the wet season (RMSE = 0.07 m) WTEMs. Previous research in Water Depth Model (WDM) generation in the Everglades focused on a conventional-based approach where a DEM is subtracted from a WTEM. This study extends the conventional-based WDM approach to a rigorous-based WDM technique where Monte Carlo simulation is used to propagate probability distributions through the proposed SLR depth model using uncertainties in the RF-based LiDAR DEM and WTEMs, vertical datums and transformations, regional SLR and soil accretion rates. It is concluded that a more rigorous-based WDM technique increases the integrity of derived products used to support and guide coastal restoration managers and planners concerned with habitat change under the challenge of SLR. Future research will be dedicated to the extension of this technique to model both increased water depths and saltwater intrusion due to SLR (saltwater inundation).
Show less - Date Issued
- 2018
- PURL
- http://purl.flvc.org/fau/fd/FA00005991
- Subject Headings
- Everglades (Fla.), Sea level rise, Coastal ecology--Florida, Everglades (Fla)--Environmental conditions, Impact assessment
- Format
- Document (PDF)
- Title
- MONITORING WADING BIRD COLONIES USING ACOUSTIC SAMPLING AND REGIONAL SHIFTS IN WADING BIRD NEST ABUNDANCES IN A PULSED WETLAND SYSTEM.
- Creator
- Larson, Rachel C., Gawlik, Dale E., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
- Abstract/Description
-
Wetland loss and degradation have led to the development of restoration programs worldwide, many of which monitor wading bird populations as indicators of wetland quality. Therefore, efficient, standardized monitoring is integral to restoration progress. I tested the use of passive acoustic monitoring to estimate nest abundances and provisioning rates in wading bird colonies and examined regional nesting dynamics in the Florida Everglades, where a long monitoring record enables analysis of...
Show moreWetland loss and degradation have led to the development of restoration programs worldwide, many of which monitor wading bird populations as indicators of wetland quality. Therefore, efficient, standardized monitoring is integral to restoration progress. I tested the use of passive acoustic monitoring to estimate nest abundances and provisioning rates in wading bird colonies and examined regional nesting dynamics in the Florida Everglades, where a long monitoring record enables analysis of nesting patterns relative to hydrologic changes. I found that call rates can serve as indices of colony nest abundances and begging call rate and timing are indicative of provisioning events. Nesting dynamics suggested that resource availability is asynchronous between regions of the Everglades, but the degree of asynchrony varies with species. The conclusions of this study will facilitate the long-term monitoring of wading bird nesting trends, which are important measures of wetland restoration in Florida and worldwide.
Show less - Date Issued
- 2021
- PURL
- http://purl.flvc.org/fau/fd/FA00013771
- Subject Headings
- Wetland restoration, Wading birds, Everglades (Fla.), Acoustics
- Format
- Document (PDF)
- Title
- POPULATION ECOLOGY AND VITAL RATES OF APPLE SNAILS (POMACEA SPP.) IN WETLANDS.
- Creator
- Barrus, Nathan T., Dorn, Nathan J., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
- Abstract/Description
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In this thesis, I explored the abiotic and biotic factors that explain the variation in reproduction, survival, and individual growth of the Florida Apple Snail (Pomacea paludosa), and I combined reproduction, survival, and individual growth to determine the factors limiting Florida Apple Snail populations. First, I examined how the variation in reproduction of the Florida Apple Snail and another non-native congener (P. maculata) can be explained by depth, temperature, photoperiod, and adult...
Show moreIn this thesis, I explored the abiotic and biotic factors that explain the variation in reproduction, survival, and individual growth of the Florida Apple Snail (Pomacea paludosa), and I combined reproduction, survival, and individual growth to determine the factors limiting Florida Apple Snail populations. First, I examined how the variation in reproduction of the Florida Apple Snail and another non-native congener (P. maculata) can be explained by depth, temperature, photoperiod, and adult densities. I also examined how metaphyton total phosphorus (TP) influenced individual growth rates of both species. I found that P. paludosa optimally reproduce in shallower water than P. maculata, that both species respond positively to increased metaphyton TP, and that P. paludosa respond weaker to variation in metaphtyon TP than P. maculata. Then, I examined individual growth across seasons, and examined how size-dependent survival varied across seasons in and out of the presence predators. I also investigated predators that strongly influence survival rates. I found that individual growth was slower in the dry season than the wet season, that survival was not size-dependent nor seasonal when predators were excluded from cages, and that survival was size-dependent in the dry season but not the wet season when in the presence of predators. Greater Sirens and Giant Water Bugs were found to be strong predators of P. paludosa < 10 mm Shell Length (SL), Greater Siren and Giant Water Bugs seasonal abundances were responsible for the differences in size-dependent survival across seasons. Finally, I incorporated differences in ideal hydrological and temperature conditions for reproduction, seasonal differences in individual growth, and changes in survival in and out of the presence of predators onto a zero-population growth isocline. I found that optimal hydrological and temperature conditions, and increased growth in the dry season, could not make up for losses of snails < 10 mm SL by predators which suggested that predators are limiting P. paludosa populations in our study area.
Show less - Date Issued
- 2022
- PURL
- http://purl.flvc.org/fau/fd/FA00013919
- Subject Headings
- Florida applesnail, Population ecology, Everglades (Fla.)
- Format
- Document (PDF)
- Title
- SPATIAL ECOLOGY OF BOBCATS (LYNX RUFUS) ON EVERGLADES TREE ISLANDS.
- Creator
- Buckman, Katherine, Dom, Nathan, Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
- Abstract/Description
-
Bobcats (Lynx rufos) that inhabit tree islands of the Everglades, an expansive wetland in southern Florida. Bobcats are understudied in Florida and wetland ecosystems, and my objective was to identify factors driving their use of tree islands. I hypothesized that tree island size, distance between islands, and clusters of islands might influence occupancy. Additionally, I tested for effects of water levels and the Burmese Python invasion on bobcat occupancy. I built detection histories using...
Show moreBobcats (Lynx rufos) that inhabit tree islands of the Everglades, an expansive wetland in southern Florida. Bobcats are understudied in Florida and wetland ecosystems, and my objective was to identify factors driving their use of tree islands. I hypothesized that tree island size, distance between islands, and clusters of islands might influence occupancy. Additionally, I tested for effects of water levels and the Burmese Python invasion on bobcat occupancy. I built detection histories using 1,855 bobcat images from camera traps set on 87 tree islands in a -2,350 km2 managed conservation area from 2005-2019 and tested hypotheses about bobcat use relative to habitat and hydrologic covariates. Bobcat occupancy was significantly diminished when Burmese python densities exceeded 2.5 pythons/km2• Occupancy probability also increased with increasing densities of tree islands around the focal island. Effects of high water levels were less clear, but suggested a slight reduction in island occupancy with deeper water in the surrounding wetlands. My results suggest that managing for high tree island density and low densities of Burmese pythons will have stronger effects on bobcat habitat use than specific water levels.
Show less - Date Issued
- 2021
- PURL
- http://purl.flvc.org/fau/fd/FA00013846
- Subject Headings
- Lynx rufus, Bobcat, Spatial ecology, Everglades (Fla.)
- Format
- Document (PDF)
- Title
- Using Hydrogeophysical Methods for Investigating Carbon Dynamics in the Greater Everglades Watershed: Implications for the Spatial and Temporal Variability in Carbon Stocks and Biogenic Gas Fluxes.
- Creator
- McClellan, Matthew D., Comas, Xavier, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
- Abstract/Description
-
Peat soils store a large fraction of the global soil carbon (C) pool and comprise 95% of wetland C stocks. They also have the capability to produce and release significant amounts of greenhouse gasses (CO2, CH4) into the atmosphere. Most studies of wetland soil C and gas flux dynamics have been done in expansive peatlands in northern boreal and subarctic biomes. However, wetlands in temperate and tropical climates are vastly understudied despite accounting for more than 20% of the global...
Show morePeat soils store a large fraction of the global soil carbon (C) pool and comprise 95% of wetland C stocks. They also have the capability to produce and release significant amounts of greenhouse gasses (CO2, CH4) into the atmosphere. Most studies of wetland soil C and gas flux dynamics have been done in expansive peatlands in northern boreal and subarctic biomes. However, wetlands in temperate and tropical climates are vastly understudied despite accounting for more than 20% of the global peatland C stock and storing large amounts of biogenic gasses Although studies investigating greenhouse gas dynamics from peatlands have increased during the last decade, the spatial and temporal distribution of these gases still remains highly uncertain, mainly due to the limitations in terms of spatial and temporal resolution and invasive nature of most methods traditionally used. This thesis combines a series of field and laboratory studies at several sites in the Greater Everglades as examples to show the potential of hydrogeophysical methods to better understand: 1) the belowground C distribution and overall contribution to the global C stocks of certain wetlands (Chapter 2); and 2) the spatial and temporal variability in both C accumulation and releases from peat soil monoliths from several wetland sites in the Greater Everglades (Chapter 3 and 4). To estimate belowground C in the field, I used a combination of indirect non-invasive geophysical methods (GPR), aerial imagery, and direct measurements (coring) to estimate the contribution of subtropical depressional wetlands to the total C stock of pine flatwoods landscape at the Disney Wilderness Preserve (DWP, Orlando, FL). Three-dimensional (3D) GPR surveys were used to define the thickness of stratigraphic layers from the wetland surface to the mineral soil interface within depressional wetlands. Depth-profile cores in conjunction with C core analysis were utilized to visually confirm depths of each interface and estimate changes in soil C content with depth and were ultimately used to estimate total peat volume and C stock for each depressional wetland. Aerial photographs were used to develop a relationship between surface area and total wetland C stock, that were applied to estimate total landscape C stock of all depressional wetlands throughout the entire preserve. Additionally, low-frequency GPR surveys were conducted to image the stratigraphy underneath the peat basin of depressional wetlands to depict lithological controls on the formational processes of depressional wetlands at the DWP. Spatial and temporal variability in biogenic greenhouse gas (i.e. methane and carbon dioxide) production and release were investigated at the laboratory scale. Two 38 liter (0.5 m x 0.23 m x 0.3 m) peat monoliths from two different wetland ecosystems in central Florida (sawgrass peatland and a wet prairie) were compared in order to understand whether changes in matrix properties influence gas dynamics in a controlled environment (i.e. constant temperature). Gas content variability (i.e. build-up and release) within the peat matrix was estimated using a series of high frequency (1.2 GHz) GPR transects along each sample about three times a week. An array of gas traps (eight per sample) fitted with time-lapse cameras were also used in order to constrain GPR measurements and capture gas releases at 15-minute intervals. Gas chromatography was performed on gas samples extracted from the traps to determine CH4 and CO2 content. Also, at the lab scale, temporal variability in biogenic gas accumulation and release was investigated in a large 0.073 m3 peat monolith from the Blue Cypress Preserve in central Florida. An autonomous rail system was constructed in order to estimate gas content variability (i.e. build-up and release) within the peat matrix using a series of continuous GPR transects along the sample. This system ran virtually nonstop using high frequency (1.2 GHz) antennas. GPR measurements were again constrained with an array of gas traps (6) fitted with time-lapse cameras and gas chromatography. The aim of this study is to better constrain temporal scale, and better understand the heterogeneous nature (both in time and space) of gas releases from peat soils.
Show less - Date Issued
- 2019
- PURL
- http://purl.flvc.org/fau/fd/FA00013238
- Subject Headings
- Greenhouse gases, Everglades (Fla.), Peatlands, Carbon, Bogenic gas
- Format
- Document (PDF)
