Joel C. Trexler

• Ph. D.
• Director at Florida State University

Ecosystem engineering is a facilitative interaction that generates bottom‐up extrinsic variability that may increase species coexistence, particularly along a stress/disturbance gradient. American alligators (Alligator mississippiensis) create and maintain ‘alligator ponds’ that serve as dry‐season refuges for other animals. During seasonal water r...

Songbird reproductive success can decline from consuming mercury-contaminated aquatic insects, but assessments of hydrologic conditions influencing songbird mercury exposure are lacking. We monitored breast feather total mercury (THg) concentrations and reproductive success in the U.S. federally listed endangered Cape Sable Seaside Sparrow (CSSS: A...

Bioturbation (sediment disturbance by animal actions) effects on nutrient cycling and nutrient levels in surface waters are difficult to quantify, in part because the diversity and magnitude of species‐specific influences are poorly understood. These influences may have consequences for the management of the trophic state of freshwater ecosystems....

Irruptive or boom-and-bust population dynamics, also known as ‘outbreaks’, are an important phenomenon that has been noted in biological invasions at least since Charles Elton’s classic book was published in 1958. Community-level consequences of irruptive dynamics are poorly documented and invasive species provide excellent systems for their study....

Phenotypic plasticity, the ability of a single genotype to produce different phenotypes under different environmental conditions, plays a profound role in several areas of evolutionary biology. One important role is as an adaptation to a variable environment. While plasticity is extremely well documented in response to many environmental factors, t...

Phenotypic plasticity, the ability of a single genotype to produce different phenotypes under different environmental conditions, plays a profound role in several areas of evolutionary biology. However, it is unclear how much reaction norms vary among conspecific populations and whether differences in reaction norms represent adaptations to differe...

Community assembly is influenced by disturbance intensity, sequential colonization (arrival order) of species, and interactions between species arriving early and species arriving later. We documented both intra- and interspecific patterns of colonization following hydrological disturbance using a 20-year time series of marsh-fish density at 21 stu...

The relative contribution of aquatic animals to phosphorus (P) and nitrogen (N) cycles of water bodies can be substantial. Excretion rates can be affected by seasonal environmental conditions, physiology, and body size. Determining the importance of particular species or size classes to total fauna-driven internal recycling of nutrients requires me...

Boom-bust population dynamics are long-recognized phenomena during species invasions, but few studies documented impacts of these dynamic changes. The Florida Everglades is the largest wetland in the United States, is undergoing a multi-decade hydro-restoration effort, and has been invaded by several tropical freshwater fishes. We used a 26-year da...

The potential for animals to modify spatial patterns of nutrient limitation for autotrophs and habitat availability for other members of their communities is increasingly recognized. However, net trophic effects of consumers acting as ecosystem engineers remain poorly known. The American Alligator Alligator mississippiensis is an abundant predator...

Invasive species are one of the greatest threats to ecosystems, disrupting ecosystem function and leading to the collapse and extinction of native species. While populations of native fishes in the Everglades are tied to the system's natural hydrological dynamics, Asian Swamp Eels (Monopterus albus/javanensis) are drought-resistant fish first repor...

The predator-permanence hypothesis predicts that as hydroperiod increases in lentic ecosystems, biotic interactions—mainly predation—replace physical factors like drying as the main determinant of community structure and population dynamics. We propose that the same transition occurs over time in seasonally flooded ecosystems that are connected to...

We examine temporal (seasonal) and spatial (habitat) effects on consumers' diet, trophic position, trophic niche, and food-web topology in a subtropical oligotrophic wetland to illustrate how consumers and food webs respond to hydrologic pulsing in a spatially complex ecosystem. We ask if the annual flood pulse causes fishes to undergo a trophic sh...

Mercury (Hg) is a globally distributed pollutant. Its sub-lethal effects on reproduction of birds have been used as indicators of contamination and of potential demographic effects. However, studies typically used single endpoints that might not be representative of entire reproductive cycle. We used observational data over 11 years from >1200 nest...

Addition of canals and levees to wetlands is common in hydrological management. Permanently flooded canals provide fishes with refuge from desiccation and corridors for long-distance movement, but also may present high risk of predation. Levees create barriers to movement. We evaluated the effect of canals and levees on the movement of fish in seas...

The Everglades is a large subtropical wetland that has been modified heavily by humans and now is undergoing restoration. Aquatic and semiaquatic Heteroptera (Hemiptera) in the infraorders Gerromorpha and Nepomorpha were collected in the Florida Everglades using standardized 1-m2 throw-traps. Sampling efforts were conducted in marshes distributed f...

It remains unclear how sub-lethal effects of contaminants play out in relation to other stressors encountered by free-ranging populations. Effects may be masked or influenced by interactions with field stressors such as food availability. We predicted that (1) including food availability, and particularly its interaction with Hg, would reveal or en...

Recruitment has been linked to decreases in the ratio of age-specific mortality (M′) to mass-specific growth (G′), and year-class strength may be predicted by the age when M′/G′ = 1. Hydrological stress adversely affects these parameters for species inhabiting floodplains; however, the relationship between M′ and G′ in hydrologically variable envir...

Toxin emissions and legacies are major global issues affecting many species through, among other effects, endocrine disruption and reproductive impairment. Assessment of toxin risk to wildlife focuses mostly on offspring-related metrics, while the lack of breeding initiation or early breeding failure has received less attention. We tested whether e...

Foundational ecological models characterize dispersal with two behavioral traits, speed and directional bias. We hypothesized that these two traits can predict the order of colonization by fishes in a heterogenous landscape. Colonization patterns following hydrological disturbance were documented from a 20-year multi-site time series of marsh fish,...

Authors would like to update the incorrect version of Fig. 4 which was incorrectly published in original publication.

In Figure 4, the axes were not labeled correctly in panels A and B. The correct Figure 4 appears below. Panel A is corrected to show increasing speed and directedness and Panel B is corrected to show decreasing speed and directedness. Results are described correctly in the text under section "Ecological Applications".

Non-native species can simultaneously affect ecological structures, functions, and services of the invaded ecosystem. In this paper, we report that the study of non-native species impacts on ecosystem function is an emerging topic in aquatic ecology, though studies measuring functions remain relatively uncommon. We hypothesized that study of ecosys...

Your article is protected by copyright and all rights are held exclusively by Springer Nature Switzerland AG. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposi...

• The Everglades has captured the imagination as a “frontier,” a “river of grass,” and a “unique ecosystem.” • Humans have occupied the Everglades for thousands of years and they have modified it throughout that history, although modern engineering modifactions have altered its fundamental ecological structure and function. • Several features of...

We develop simple diffusion-advection models to estimate the average time it takes fish to reach one of the boundaries of an enclosure and the population distribution over time moving in the enclosure (such as a lake or slough). We start with a combination of random walks and directed movement and then, from these, proceeding to the associated Part...

We develop simple diffusion-advection models to estimate the average time it takes fish to reach one of the boundaries of an enclosure and the population distribution over time moving in the enclosure (such as a lake or slough). We start with a combination of random walks and directed movement and then, from these, proceeding to the associated Part...

Combining information from active and passive sampling of mobile animals is challenging because active‐sampling data are affected by limited detection of rare or sparse taxa, while passive‐sampling data reflect both density and movement. We propose that a model‐based analysis allows information to be combined between these methods to interpret vari...

The ability of organisms to cross ecosystem boundaries is an important catalyst of evolutionary diversification. The genus Poecilia (mollies and guppies) is an excellent system for studying ecosystem transitions because species display a range of salinity and dietary preferences, with herbivory concentrated in the subgenus Mollienesia. We reconstru...

Combining information from active and passive sampling of mobile animals is challenging because active sampling data are affected by limited detection of rare or sparse taxa, while passive sampling data reflect both density and movement. We propose that a model-based analysis allows information to be combined between these methods to interpret vari...

The ability of organisms to cross ecosystem boundaries is an important catalyst of evolutionary diversification. The genus Poecilia (mollies and guppies) is an excellent system for studying ecosystem transitions because species display a range of salinity and dietary preferences, with herbivory concentrated in the subgenus Mollienesia. We reconstru...

Hydrological variation is believed to be the main density-independent factor that controls fish recruitment in floodplain ecosystems. However, our ability to fully understand these controls is greatly impeded by the size-selective nature of sampling gear. To illustrate the benefits of estimating the effects of size-selective bias on population para...

Herbivory is thought to be an inefficient diet, but it independently evolved from carnivorous ancestors in many metazoan groups, suggesting that plant‐eating is adaptive in some circumstances. In this study, we tested two hypotheses to explain the adaptive evolution of herbivory: (i) the Heterotroph Facilitation hypothesis (herbivory is adaptive be...

In large-scale conservation decisions, scenario planning identifies key uncertainties of ecosystem function linked to ecological drivers affected by management, incorporates ecological feedbacks, and scales up to answer questions robust to alternative futures. Wetland restoration planning requires an understanding of how proposed changes in surface...

In flood-pulsed ecosystems, hydrology and landscape structure mediate transfers of energy up the food chain by expanding and contracting in area, enabling spatial expansion and growth of fish populations during rising water levels, and subsequent concentration during the drying phase. Connectivity of flooded areas is dynamic as waters rise and fall...

Animals living in patchy environments may depend on resource pulses to meet the high energetic demands of breeding. We developed two primary a priori hypotheses to examine relationships between three categories of wading bird prey biomass and covariates hypothesized to affect the concentration of aquatic fauna, a pulsed resource for breeding wading...

Justification for Variable Selection. (PDF)

Akaike's Information Criterion model selection for factors affecting fish, crayfish and grass shrimp biomass in the Florida Everglades, USA. (PDF)

A schematic of the sampling components within a primary sampling unit. (PDF)

Manuscript data and metadata. (PDF)

Herbivory is thought to be nutritionally inefficient relative to carnivory and omnivory, but herbivory evolved from carnivory in many terrestrial and aquatic lineages, suggesting that there are advantages of eating plants. Herbivory has been well-studied in both terrestrial and aquatic systems, and there is abundant information on feedbacks between...

The pre-drainage Everglades was characterized by a continuum of clean, flowing freshwater from just south of present-day Orlando, down the Kissimmee River, through Lake Okeechobee, across the “River of Grass”, and ultimately into Florida Bay and the Gulf of Mexico. Today, the system is highly managed and impacted by a network of pumps, gates, culve...

Fire in uplands and wetlands results in a release of nutrients and increased light in the burned area. However, fire effects on aquatic community dynamics are not well understood. We hypothesized that the addition of light and nutrients resulting from prescribed burns in wetlands increases periphyton biomass and supports increased standing stock of...

The Everglades is an internationally recognized iconic, wetland threatened by water extraction, channelization, and anthropogenic nutrient enrichment. It is a large oligotrophic, karstic wetland with seasonal climate influenced by its location at the southern tip of the Florida peninsula between the subtropical Western Atlantic and the Gulf of Mexi...

Background/Question/Methods The possibility of thresholds and other complex, non-linear dynamical properties of ecological systems is prompting a paradigm shift in ecosystem management practices. However, not all ecosystems exhibit threshold-like behavior and the dynamics associated with directional change in environmental drivers may well be ecosy...

Balancing trade-offs between avoiding predators and acquiring food enables animals to maximize fitness. Quantifying their relative contribution to vital rates in nature is challenging because predator abundance and nutrient enrichment are often confounded. We employed a reciprocal transplant study design to separate these confounded effects on grow...

.

It is uncertain how climate change will impact hydrologic drivers of wildlife population dynamics in freshwater wetlands of the Florida Everglades, or how to accommodate this uncertainty in restoration decisions. Using projections of climate scenarios for the year 2060, we evaluated how several possible futures could affect wildlife populations (wa...

Fish with perennial life histories that inhabit ecosystems where water availability fluctuates seasonally must have movement behavior that accommodates this environmental change. Landscape structure is expected to influence magnitude and direction of these movements by affecting the distribution of water in space and time. Predicting the effects of...

Spatial ecology and movement strategies of aquatic organisms may limit their response to human-caused drying of wetland habitats. We characterized the movement strategies of the most abundant species of fish in the wetlands of the Everglades (USA) to better understand how they cope with annual fluctuations in aquatic habitat size. Over a six-year p...

Freshwater benthic microbial communities display a diversity of growth forms that shape food web structure and function through infl uencing availability of food and predation refuges of primary consumers. Periphyton, an assemblage of microfl ora growing on substrates (Wetzel 1983), includes a diversity of autotrophs and saprophytes (microscopic al...

The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus...

List of sampling locations (UTMs) and corresponding measurements of habitat characteristics. Includes metadata.

Spatial heterogeneity in habitat conditions within a landscape should influence degree of movement of species between natural and artificial environments. For wetland landscapes, this functional connectivity was predicted to emerge from the influence of spatiotemporal patterns of depth on permeability of habitat edges and distance and directedness...

Key to predicting impacts of predation is understanding the mechanisms through which predators impact prey populations. While consumptive effects are well-known, non-consumptive predator effects (risk effects) are increasingly being recognized as important. Studies of risk effects, however, have focused largely on how trade-offs between food and sa...

Space-for-time substitution is often used in predictive models because long-term time-series data are not available. Critics of this method suggest factors other than the target driver may affect ecosystem response and could vary spatially, producing misleading results. Monitoring data from the Florida Everglades were used to test whether spatial d...

Fish sampling is an important component of wetland research, management, conservation, monitoring, and assessment programs, and studies of fish abundance, productivity, and community structure can provide important information about wetland condition and health. In this chapter, we discuss considerations specific to wetland sampling, including issu...

We isolated and characterized 18 microsatellite loci from the Mayan cichlid, Cichlasoma urophthalmus. Loci were screened for 24 specimens from a total of seven sites in south Florida, Mexico, Belize and Honduras. The number of alleles per locus ranged from 3 to 21, observed heterozygosity ranged from 0.208 to 0.875, and the probability of identity...

Background/Question/Methods Animal movement strategies need to adapt to changing conditions in dynamic environments. Wetlands present fish with extreme challenges to cope with seasonally expanding and contracting habitat. Furthermore, wetlands commonly experience anthropogenic modifications that further challenge the ability of fish to respond ad...

Background/Question/Methods The metacommunity concept represents a major advance in ecology because it provides a framework to link ecological processes with biodiversity patterns at multiple scales. Metacommunities consist of assemblages of interacting species, typically linked over broad spatial scales. The structure of a metacommunity is an em...

Background/Question/Methods Invasive species are a major threat to biodiversity and ecosystem function, and are of increasing economic concern. Yet, ecologists have struggled to explain why some species succeed while others do not. One hypothesis is that a population with high genetic diversity should be able to adapt quickly to new environments,...

.

Non-native fishes present a management challenge to maintaining Everglades National Park (ENP) in a natural state. We summarized data from long-term fish monitoring studies in ENP and reviewed the timing of introductions relative to water-management changes. Beginning in the early 1950s, management actions have added canals, altered wetland habitat...

We hypothesized that fishes in short-hydroperiod wetlands display pulses in activity tied to seasonal flooding and drying, with relatively low activity during intervening periods. To evaluate this hypothesis, sampling devices that funnel fish into traps (drift fences) were used to investigate fish movement across the Everglades, U.S.A. Samples were...

Water flow and flooding duration in wetlands influence the structure and productivity of microbial communities partly through their influence on nutrient loading. The effect of flow-regulated nutrient loads is especially relevant for microbial communities in nutrient-poor settings, where delivery controls nutrient uptake rates and the intensity of...

We evaluated metacommunity hypotheses of landscape arrangement (indicative of dispersal limitation) and environmental gradients (hydroperiod and nutrients) in structuring macroinvertebrate and fish communities in the southern Everglades. We used samples collected at sites from the eastern boundary of the southern Everglades and from Shark River Slo...

Predation, predation risk, and resource quality affect suites of prey traits that collectively impact individual fitness, population dynamics, and community structure. However, studies of multitrophic level effects generally focus on a single prey trait, failing to capture trade-offs among suites of covarying traits that govern population responses...

1. The niche variation hypothesis predicts that among‐individual variation in niche use will increase in the presence of intraspecific competition and decrease in the presence of interspecific competition. We sought to determine whether the local isotopic niche breadth of fish inhabiting a wetland was best explained by competition for resources and...

The Mayan Cichlid (Cichlasoma urophthalmus) is an omnivorous fish endemic to Central America that was first recorded in South Florida in 1983. We examined their effects on native fishes in estuarine mangrove habitats between 1991 and 2006. Four major cold fronts passed during the study period and each killed many Mayan Cichlids, providing multiple...

Abstract Many inferences about contemporary rates of gene flow are based on the assumption that the observed genetic structure among populations is stable. Recent studies have uncovered several cases in which this assumption is tenuous. Most of those studies have focused on the effects that regular environmental fluctuations can have on genetic str...

Movement strategies of small forage fish (<8 cm total length) between temporary and permanent wetland habitats affect their overall population growth and biomass concentrations, i.e., availability to predators. These fish are often the key energy link between primary producers and top predators, such as wading birds, which require high concentratio...

We developed diatom-based prediction models of hydrology and periphyton abundance to inform assessment tools for a hydrologically managed wetland. Because hydrology is an important driver of ecosystem change, hydrologic alterations by restoration efforts could modify biological responses, such as periphyton characteristics. In karstic wetlands, dia...

The Mayan Cichlid (Cichlasoma urophthalmus) is an omnivorous fish endemic to Central America that was first recorded in South Florida in 1983. We examined their effects on native fishes in estuarine mangrove habitats between 1991 and 2006. Four major cold fronts passed during the study period and each killed many Mayan Cichlids, providing multiple...

Diel changes in movement and activity of fishes typically occur to reduce predation or competition, resulting in changes in abundance and assemblage structure amongst habitats. The ability of fish to disperse or migrate on a diel basis is largely dependent upon the level of connectivity across habitats. The goal of this study was to investigate die...

Adaptive life history strategies allow small fish communities in the subtropical freshwater Everglades to thrive despite seasonal contraction and expansion of habitat due to seasonally varying rainfall. Understanding relationships between hydroperiod and spatial and temporal biomass production patterns will greatly aid conservation and management o...

Background/Question/Methods The pervasiveness of among-individual variation in resource utilization has been demonstrated in many species and may potentially alter ecosystem function, population stability, and species interactions. However, the causes of variation among individuals are still poorly understood. This study explores potential mechan...

Background/Question/Methods Movement by animals can have major influence on metapopulations and metacommunities. Florida’s Everglades ecosystem is an important wetland with annual variation in hydrology. Small fish rapidly move in and out of flooding or drying portions of the wetland more rapidly than predicted by reaction-diffusion. Modeling sug...

Background/Question/Methods Predators can influence communities in spatially and temporally heterogeneous landscapes like seasonally flooded wetlands such as the Everglades. Seasonal fluctuation in water levels drive population control of small fishes. Large piscivorous fishes may also affect the population levels of small fishes and historically...

Background/Question/Methods Invasive species are a major threat to biodiversity and ecosystem function, and are of increasing economic concern. Yet, ecologists have struggled to explain why some species succeed while others do not. One hypothesis is that a population with high genetic diversity should be able to adapt quickly to new environments,...

Background/Question/Methods Currently two distinct models of community assembly and diversity patterns dominate the ecological literature. In niche-based models species are sorted by environmental filters, whereas in neutral models community diversity and assembly is determined by connectivity and heterogeneity in regional sources pools. The relat...