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Title: Factors influencing wetland reptile and amphibian community composition.
Creator: Holbrook, Joshua D., Dorn, Nathan, Graduate College
Abstract/Description: Purpose: To quantify Reptile and Amphibian community assemblages in freshwater wetlands and determine biotic and abiotic factors e.g., wetland permanence and presence of large fish that may influence assemblage structure. Methods: Wetland Reptile and Amphibians were monitored via passive trapping at 20 wetland sites at Jonathan Dickinson State Park JDSP in Hobe Sound, FL. Trapping at JDSP occurred over a single wet season June-November period and community assemblages were analyzed...
Show morePurpose: To quantify Reptile and Amphibian community assemblages in freshwater wetlands and determine biotic and abiotic factors e.g., wetland permanence and presence of large fish that may influence assemblage structure. Methods: Wetland Reptile and Amphibians were monitored via passive trapping at 20 wetland sites at Jonathan Dickinson State Park JDSP in Hobe Sound, FL. Trapping at JDSP occurred over a single wet season June-November period and community assemblages were analyzed statistically using multivariate techniques. Results: Hierarchical clustering revealed two primary assemblages, which included 70 of wetlands. One assemblage, typical in wetlands containing large-bodied fish, consisted of two or three snake species and low abundances of anurans in the family Ranidae. The second assemblage, typical of fishless wetlands, generally had abundant anurans in the families Hylidae and Ranidae. Conclusion: Though distance from other wetlands as well as wetland permanence also influenced assemblage structure, fish presence/absence was a larger determinant of herpetofaunal communities.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00005822
Format: Document (PDF)

Title: Effects of habitat structure and local predators on dragonfly oviposition and success.
Creator: Knorp, Natalie E., Dorn, Nathan, Graduate College
Date Issued: 2013-04-12
PURL: http://purl.flvc.org/fcla/dt/3361936
Subject Headings: Dragonflies, Oviposition
Format: Document (PDF)

Title: Crayfish (Procambarus spp.) sorting and density effects across a predator gradient.
Creator: Kellogg, Christopher M., Dorn, Nathan, Graduate College
Date Issued: 2011-04-08
PURL: http://purl.flvc.org/fcla/dt/3165803
Subject Headings: Crayfish culture, Predation (Biology), Sunfishes
Format: Document (PDF)

Title: Cascading effects of vegetation on peat soil properties and crayfish survival in the Florida Everglades.
Creator: Chapman, Alexander, Benscoter, Brian, Dorn, Nathan, Graduate College
Date Issued: 2013-04-12
PURL: http://purl.flvc.org/fcla/dt/3361281
Subject Headings: Everglades (Fla.), Peat soils, Crayfish, Cattails, Multitrophic interactions (Ecology)
Format: Document (PDF)

Title: Quantifying Wading Bird Activity in Drying Wetlands Using Time Lapse Imagery.
Creator: Campbell, Hannah, Dorn, Nathan, Office of Undergraduate Research and Inquiry
Abstract/Description: The purpose of this research was to quantify wading bird hourly and daily foraging activity in a drying wetland. We sought to determine the hours of peak activity and identify water depths that facilitate high foraging activity. Our results indicated that 56% of daily activity occurred between 0600 – 0800 h and >95% of the daily activity was found in images taken between 0600 and 1400 h. The wading bird activity showed little variation and no obvious correlation with water depth fluctuations ...
Show moreThe purpose of this research was to quantify wading bird hourly and daily foraging activity in a drying wetland. We sought to determine the hours of peak activity and identify water depths that facilitate high foraging activity. Our results indicated that 56% of daily activity occurred between 0600 – 0800 h and >95% of the daily activity was found in images taken between 0600 and 1400 h. The wading bird activity showed little variation and no obvious correlation with water depth fluctuations (highest recorded density = 2.1 birds/ha at 14.9 cm depth; lowest recorded density = 0.05 birds/ha at 35.1 cm depth). The wading bird activity occurring between 0600 – 1400 h accounts for >95% of daily activity. We conclude that a study of water depth and average wading bird density earlier in the nesting season is needed for a clearer effect of water depth on wading bird foraging activity.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00005562
Subject Headings: College students --Research --United States.
Format: Document (PDF)

Title: The enigmatic Marmorkrebs (marbled crayfish) is the parthenogenetic form of Procambarus fallax (Hagen, 1870).
Creator: Peer Martin, Nathan J. Dorn, Tadashi Kawai, Craig van der Heiden, Gerhard Scholtz
Abstract/Description: A mysterious parthenogenetic cambarid crayfish (the Marmorkrebs) has been spreading across the globe for the past decade. We compare this crayfish directly to two other cambarids, Procambarus fallax and P. alleni, that have been suggested to be related or even identical to the Marmorkrebs. Using external morphology and sequences of two mitochondrial genes we show clear correspondences between Marmorkrebs and P. fallax, a species found natively throughout peninsular Florida, USA. Based on...
Show moreA mysterious parthenogenetic cambarid crayfish (the Marmorkrebs) has been spreading across the globe for the past decade. We compare this crayfish directly to two other cambarids, Procambarus fallax and P. alleni, that have been suggested to be related or even identical to the Marmorkrebs. Using external morphology and sequences of two mitochondrial genes we show clear correspondences between Marmorkrebs and P. fallax, a species found natively throughout peninsular Florida, USA. Based on these congruent results we suggest that the Marmorkrebs is the parthenogenetic form of P. fallax. This finding has potential evolutionary and ecological implications at several levels. The Marmorkrebs might be a type of geographical parthenogenesis, but a natural population in the wild is so far unknown. Furthermore, challenges arise in regard to the respective species status of the Marmorkrebs. Taxonomically we suggest that the Marmorkrebs is treated as ‘parthenogenetic form’ of P. fallax. Last but not least, the identity of this animal and its ecology has an impact for considering potential spread and effects of this species across the globe.
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Date Issued: 2010
PURL: http://purl.flvc.org/fau/fd/FAUIR000482
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: 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.
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Date Issued: 2022
PURL: http://purl.flvc.org/fau/fd/FA00013919
Subject Headings: Florida applesnail, Population ecology, Everglades (Fla.)
Format: Document (PDF)

Title: IMPORTANCE OF FRESHWATER PREY FOR NESTING WHITE IBIS EUDOCIMUS ALBUS IN SOUTHERN FLORIDA WETLANDS.
Creator: Cocoves, Tasso C., Dorn, Nathan, Florida Atlantic University, Environmental Studies Program, Charles E. Schmidt College of Science
Abstract/Description: Avian reproduction is generally resource dependent, and resource availability can vary through time and space. Wading birds breeding activity in southern Florida wetlands is limited by availability of aquatic prey, which is largely influenced by seasonal hydrodynamics. Restoration of natural hydrologic patterns is expected to increase populations and return breeding activity in the southern Everglades, but which prey support successful breeding at coastal colonies is unknown. To address this,...
Show moreAvian reproduction is generally resource dependent, and resource availability can vary through time and space. Wading birds breeding activity in southern Florida wetlands is limited by availability of aquatic prey, which is largely influenced by seasonal hydrodynamics. Restoration of natural hydrologic patterns is expected to increase populations and return breeding activity in the southern Everglades, but which prey support successful breeding at coastal colonies is unknown. To address this, I examined prey use of nesting White Ibis (Eudocimus albus) at coastal colonies in Everglades National Park (ENP) in a two-year observational study. I also examined ibis diets at nesting colonies located in three regions of the Everglades to better understand regional variation in trophic support of ibis reproduction. I found that crayfish and fish were used extensively in ENP in a year with exceptional ibis breeding activity, and I provide evidence that lengthened hydroperiods in higher elevation marl prairies may enhance crayfish production and availability in the southern Everglades. I found that crayfish were the most important prey type in all regions of the Everglades when reproductive effort was highest. These results add to the growing body of evidence that crayfish are important prey for ibis reproductive success in all parts of the Everglades, and suggest that increasing water flowing into the southern Everglades may incite greater nesting at historic colony locations. With this knowledge we can forecast how wading birds, and more generally wetlands of southern Florida, will respond to a changing environment and potential restoration scenarios.
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Date Issued: 2019
PURL: http://purl.flvc.org/fau/fd/FA00013367
Subject Headings: Eudocimus albus, White ibis, Birds--Reproduction, Nest building, Crayfish, Wetland hydrology, Everglades National Park (Fla)
Format: Document (PDF)

Title: Effects of fish on reptile and amphibian community assemblages in wetlands of variable permanence.
Creator: Holbrook, Joshua D., Dorn, Nathan, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Many herpetofaunal species are imperiled, and the causes of this are often a synergy of multiple factors. In wetlands specifically, two of the possible determinants of species occurrence and faunal community assemblage are fish presence and wetland permanence, which are not always correlated. Twenty wetlands were sampled in Jonathan Dickinson State Park, Florida, USA to observe how wetland herpetofaunal communities vary with fish, wetland permanence and other environmental factors....
Show moreMany herpetofaunal species are imperiled, and the causes of this are often a synergy of multiple factors. In wetlands specifically, two of the possible determinants of species occurrence and faunal community assemblage are fish presence and wetland permanence, which are not always correlated. Twenty wetlands were sampled in Jonathan Dickinson State Park, Florida, USA to observe how wetland herpetofaunal communities vary with fish, wetland permanence and other environmental factors. Herpetofaunal communities with and without fish were significantly different from one another and differences between herpetofaunal communities were primarily due to the contribution of four species of frogs, two generalist ranids and two specialist hylids. Wetland permanence had no observable effect on community structure. Fishless wetlands were significantly more species-rich and possessed higher numbers of individuals even for species that occurred in both fishless and fish wetlands, regardless of their permanence. These findings have implications for wetlands restoration and herpetofaunal conservation.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004203, http://purl.flvc.org/fau/fd/FA00004203
Subject Headings: Amphibian surveys -- Florida -- Jonathan Dickinson State Park, Amphibians -- Conservation, Amphibians -- Ecology, Jonathan Dickinson State Park (Fla.), Reptiles -- Conservation, Reptiles -- Ecology, Wetland ecology, Wetlands -- Environmental aspects
Format: Document (PDF)

Title: Predatory Impacts of Crayfish on Apple Snails (Pomacea paludosa and P. maculata).
Creator: Davidson, Andrew, Dorn, Nathan, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Theory predicts that when prey can reach a size refuge from predation, prey vulnerability to predation is a function of hatchling size, growth rate, and the handling limitations of its predator, which collectively influence the amount of time prey spend vulnerable. I examined the mechanistic role of prey size for the predator-prey interaction between predatory crayfish (Procambarus fallax) and apple snail prey (Pomacea paludosa and P. maculata) and found that crayfish feeding rates decreased...
Show moreTheory predicts that when prey can reach a size refuge from predation, prey vulnerability to predation is a function of hatchling size, growth rate, and the handling limitations of its predator, which collectively influence the amount of time prey spend vulnerable. I examined the mechanistic role of prey size for the predator-prey interaction between predatory crayfish (Procambarus fallax) and apple snail prey (Pomacea paludosa and P. maculata) and found that crayfish feeding rates decreased with snail size, such that smaller hatchling P. maculata were more than twenty times more vulnerable than hatchling P. paludosa. Experimental manipulations of productivity increased apple snail growth rates, reducing the effects of predatory crayfish on P. maculata survivorship, but not P. paludosa survivorship. My results indicate that when prey can reach a size refuge from predation, increased system productivity decreases predator limitation of that prey.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004760, http://purl.flvc.org/fau/fd/FA00004760
Subject Headings: Predation (Biology), Gastropoda--Physiology., Florida applesnail--Habitat., Florida applesnail--Environmental aspects.
Format: Document (PDF)

Title: POPULATION LIMITATIONS OF THE FLORIDA APPLE SNAIL (POMACEA PALUDOSA).
Creator: Drumheller, Danielle, Dorn, Nathan, Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
Abstract/Description: In this thesis I examined factors limiting population success of apple snails (Pomacea spp.) in Florida wetlands. First, I examined effects of summertime hydropattern in replicated wetlands on reproduction and juvenile growth. Annual reproductive effort of Florida apple snails (Pomacea paludosa) and the invasive apple snail P. maculata under was not affected by deeper water in the summer. When juvenile P. paludosa were forced to grow in reportedly favorable and relatively deeper summertime...
Show moreIn this thesis I examined factors limiting population success of apple snails (Pomacea spp.) in Florida wetlands. First, I examined effects of summertime hydropattern in replicated wetlands on reproduction and juvenile growth. Annual reproductive effort of Florida apple snails (Pomacea paludosa) and the invasive apple snail P. maculata under was not affected by deeper water in the summer. When juvenile P. paludosa were forced to grow in reportedly favorable and relatively deeper summertime depths survival was high between treatments and growth was unaffected. In the other chapter I examined interactions between the two snails with a series of observations and experiments. I examined historical data on the assemblages and found that P. paludosa were locally extinguished in one of the wetlands within six years of invasion by P. maculata. Two field experiments gave conflicting results about the importance of interspecific inhibition of P. paludosa by the invasive snail, but in either case resource reduction could not be demonstrated. Lab exposure to P. maculata chemical cues strongly inhibited P. paludosa growth, although P. paludosa did not behaviorally avoid mucus of P. maculata. In mesocosms Pomacea paludosa growth was reduced with increasing exposure to adult P. maculata waterborne cues, and the results suggest that contact with mucus at a low exposure may even have a greater inhibiting effect. This interspecific direct chemical growth inhibition was novel for gastropods, but could be more generally important, and its potential impacts to P. paludosa populations should be explored further.
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Date Issued: 2020
PURL: http://purl.flvc.org/fau/fd/FA00013593
Subject Headings: Florida applesnail, Pomacea paludosa, Snail populations
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.
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Date Issued: 2021
PURL: http://purl.flvc.org/fau/fd/FA00013873
Subject Headings: Wetland ecology, Everglades (Fla.), Invertebrate communities
Format: Document (PDF)

Title: EFFECTS OF WET SEASON HYDRO-PATTERN ON CRAYFISH (PROCAMBARUS FALLAX) POPULATION DENSITY AND JUVENILE MORTALITY RISK.
Creator: Sommer, Jeffrey L., Dorn, Nathan J., Florida Atlantic University, Department of Environmental Sciences, Charles E. Schmidt College of Science
Abstract/Description: Distribution and abundance of water impacts population dynamics and habitat structure within a wetland ecosystem. It is known that drought can interfere with trophic dynamics and temporarily free crayfish from the threat of predation by population limiting fish predators in seasonal freshwater wetlands. Less is known about wet season water depths, and their effect on predator prey interactions. In order to address this, I conducted a two-and-a-half-year study in which I experimentally...
Show moreDistribution and abundance of water impacts population dynamics and habitat structure within a wetland ecosystem. It is known that drought can interfere with trophic dynamics and temporarily free crayfish from the threat of predation by population limiting fish predators in seasonal freshwater wetlands. Less is known about wet season water depths, and their effect on predator prey interactions. In order to address this, I conducted a two-and-a-half-year study in which I experimentally manipulated the wet season water depth in four 8 ha replicate wetlands of the central Everglades, allowing two wetlands to be flooded as natural rainfall patterns would allow (unconstrained hydro-pattern) and two wetlands to experience a constrained hydro-pattern in which the maximum depths to which they were flooded was limited. I discovered that crayfish, small marsh fish, and large bodied predatory fish populations were unaffected by the water depth difference between the hydro-pattern treatments. Unlike fauna, flora did respond to the hydro-pattern treatments with stem densities increasing in the wetlands under the constrained hydro-pattern treatment.
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Date Issued: 2021
PURL: http://purl.flvc.org/fau/fd/FA00013738
Subject Headings: Crayfish, Procambarus, Wetland ecology
Format: Document (PDF)

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