Are mangroves in the tropical Atlantic ripe for invasion? Exotic mangrove trees in the forests of South Florida

Abstract Two species of mangrove trees of Indo- Pacific origin have naturalized in tropical Atlantic mangrove forests in South Florida after they were planted and nurtured in botanic gardens. Two Bruguiera gymnorrhiza trees that were planted in the intertidal zone in 1940 have given rise to a population of at least 86 trees growing interspersed with native mangrove species Rhizophora mangle, Avicennia germinans and Laguncularia racemosa along 100 m of shoreline; the population is expanding at a rate of 5.6% year-1. Molecular genetic analyses confirm very low genetic diversity, as expected from a population founded by two individuals. The maximumnumber of alleles at any locus was three, and we measured reduced heterozygosity compared to native-range populations. Lumnitzera racemosa was introduced multiple times during the 1960s and 1970s, it has spread rapidly into a forest composed of native R. mangle, A. germinans, Laguncularia racemosa and Conocarpus erectus and now occupies 60,500 m2 of mangrove forest with stem densities of 24,735 ha-1. We estimate the population growth rate of Lumnitzera racemosa to be between 17 and 23% year-1. Populations of both species of naturalized mangroves are dominated by young individuals. Given the long life and water-dispersed nature of propagules of the two exotic species, it is likely that they have spread beyond our survey area. We argue that the species-depauperate nature of tropical Atlantic mangrove forests and close taxonomic relatives in the more species-rich Indo-Pacific region result in the susceptibility of tropical Atlantic mangrove forests to invasion by Indo-Pacific mangrove species.

Are mangroves in the tropical Atlantic ripe for invasion? Exotic mangrove trees in the forests of South Florida

Two species of mangrove trees of Indo- Pacific origin have naturalized in tropical Atlantic mangrove forests in South Florida after they were planted and nurtured in botanic gardens. Two Bruguiera gymnorrhiza trees that were planted in the intertidal zone in 1940 have given rise to a population of at least 86 trees growing interspersed with native mangrove species Rhizophora mangle, Avicennia germinans and Laguncularia racemosa along 100 m of shoreline; the population is expanding at a rate of 5.6% year-1. Molecular genetic analyses confirm very low genetic diversity, as expected from a population founded by two individuals. The maximumnumber of alleles at any locus was three, and we measured reduced heterozygosity compared to native-range populations. Lumnitzera racemosa was introduced multiple times during the 1960s and 1970s, it has spread rapidly into a forest composed of native R. mangle, A. germinans, Laguncularia racemosa and Conocarpus erectus and now occupies 60,500 m2 of mangrove forest with stem densities of 24,735 ha-1. We estimate the population growth rate of Lumnitzera racemosa to be between 17 and 23% year-1. Populations of both species of naturalized mangroves are dominated by young individuals. Given the long life and water-dispersed nature of propagules of the two exotic species, it is likely that they have spread beyond our survey area. We argue that the species-depauperate nature of tropical Atlantic mangrove forests and close taxonomic relatives in the more species-rich Indo-Pacific region result in the susceptibility of tropical Atlantic mangrove forests to invasion by Indo-Pacific mangrove species.

Interaction of the parasitic angiosperm {\it Cassytha filiformis\/} L. (Lauraceae) with the exotic {\it Schinus terebinthifolius\/} Raddi (Anacardiaceae) in southern Florida

Brazilian pepper (Schinus terebinthifolius) is an exotic shrub or small tree that has become well established as an invasive and highly competitive species through much of southern Florida. Love vine (Cassytha filiformis), a native parasitic plant, was noted parasitizing Brazilian pepper, apparently affecting its health. The objective of this study was to investigate the nature of this parasitic interaction in southern Florida. Brazilian pepper populations were studied to determine whether parasitism by love vine may affect growth and reproduction. Anatomical studies of love vine parasitizing Brazilian pepper determined physical aspects of the parasitic interaction at the cell and tissue level. Physiological aspects of this interaction were investigated to help describe love vine resource acquisition as a parasite on host Brazilian pepper plants, and as an autotrophic plant. An investigation of ecological aspects of this parasitic interaction was done to determine whether physical or biological aspects of habitats may contribute to love vine parasitism on Brazilian pepper. These studies indicated that: (1) parasitism by love vine significantly decreased growth and reproduction of Brazilian pepper plants; (2) anatomical and physiological investigations indicated that love vine was primarily a xylem parasite on Brazilian pepper, but that some assimilated carbon nutrients may also be acquired from the host; (3) love vine is autotrophic (i.e., hemiparasitic), but is totally dependent on its host for necessary resources; (4) the occurrence of love vine parasitism on Brazilian pepper is mediated by physical characters of the biological community. ^

Exotic meson decay widths using lattice quantum chromodynamics

Most experiments in particle physics are scattering experiments, the analysis of which leads to masses, scattering phases, decay widths and other properties of one or multi-particle systems. Until the advent of Lattice Quantum Chromodynamics (LQCD) it was difficult to compare experimental results on low energy hadron-hadron scattering processes to the predictions of QCD, the current theory of strong interactions. The reason being, at low energies the QCD coupling constant becomes large and the perturbation expansion for scattering; amplitudes does not converge. To overcome this, one puts the theory onto a lattice, imposes a momentum cutoff, and computes the integral numerically. For particle masses, predictions of LQCD agree with experiment, but the area of decay widths is largely unexplored. ^ LQCD provides ab initio access to unusual hadrons like exotic mesons that are predicted to contain real gluonic structure. To study decays of these type resonances the energy spectra of a two-particle decay state in a finite volume of dimension L can be related to the associated scattering phase shift δ(k) at momentum k through exact formulae derived by Lüscher. Because the spectra can be computed using numerical Monte Carlo techniques, the scattering phases can thus be determined using Lüscher's formulae, and the corresponding decay widths can be found by fitting Breit-Wigner functions. ^ Results of such a decay width calculation for an exotic hybrid( h) meson (JPC = 1-+) are presented for the decay channel h → πa 1. This calculation employed Lüscher's formulae and an approximation of LQCD called the quenched approximation. Energy spectra for the h and πa1 systems were extracted using eigenvalues of a correlation matrix, and the corresponding scattering phase shifts were determined for a discrete set of πa1 momenta. Although the number of phase shift data points was sparse, fits to a Breit-Wigner model were made, resulting in a decay width of about 60 MeV. ^

Wayside Trees of Tropical Florida : a guide to the native and exotic trees and palms of Miami and tropical south Florida

Wayside Trees is an beautifully illustrated guide to Florida trees growing south of Lake Okeechobee. It covers both native and exotic species in the areas of Miami to Palm Beach on the east coast, and Naples to Fort Meyers on the west. The introduction describes environmental, cultural and economic importance of trees, while a non-technical key provides a means for even non-specialists to identify the 167 most common species. The bulk of the book consists of illustrated descriptions of the trees, arranged by plant family, and includes ecological and cultural information on each species. Lavishly illustrated with over 1200 color photographs and diagrams, the book is designed to serve homeowners, gardeners, teachers and students, as well as environmental professionals. It is also a useful guide to urban tropical trees growing outside south Florida. The authors, a botanist and a graphic artist, have 70 collective years of experience living, working, and loving the trees of south Florida.

Life history trade-offs and community dynamics of small fishes in a seasonally pulsed wetland

We used a one-dimensional, spatially explicit model to simulate the community of small fishes in the freshwater wetlands of southern Florida, USA. The seasonality of rainfall in these wetlands causes annual fluctuations in the amount of flooded area. We modeled fish populations that differed from each other only in efficiency of resource utilization and dispersal ability. The simulations showed that these trade-offs, along with the spatial and temporal variability of the environment, allow coexistence of several species competing exploitatively for a common resource type. This mechanism, while sharing some characteristics with other mechanisms proposed for coexistence of competing species, is novel in detail. Simulated fish densities resembled patterns observed in Everglades empirical data. Cells with hydroperiods less than 6 months accumulated negligible fish biomass. One unique model result was that, when multiple species coexisted, it was possible for one of the coexisting species to have both lower local resource utilization efficiency and lower dispersal ability than one of the other species. This counterintuitive result is a consequence of stronger effects of other competitors on the superior species.

Invasive exotic plant indicators for ecosystem restoration: An example from the Everglades restoration program

We have developed a comprehensive ecological indicator for invasive exotic plants, a human-influenced component of the Everglades that could threaten the success of the restoration initiative. Following development of a conceptual ecological model for invasive exotic species, presented as a companion paper in this special issue, we developed criteria to evaluate existing invasive exotic monitoring programs for use in developing invasive exotic performance measures. We then used data from the selected monitoring programs to define specific performance measures, using species presence and abundance as the basis of the indicator for invasive exotic plants. We then developed a series of questions used to evaluate region and/or individual species status with respect to invasion. Finally, we used an expert panel who had answered the questions for invasive exotic plants in the Everglades Lake Okeechobee model to develop a stoplight restoration report card to communicate invasive exotic plant status. The report card system provides a way to effectively evaluate and present indicator data to managers, policy makers, and the public using a uniform format among indicators. Collectively, the model, monitoring assessment, performance measures, and report card enable us to evaluate how invasive plants are impacting the restoration program and how effectively that impact is being managed. Applied through time, our approach also allows us to follow the progress of management actions to control the spread and reduce the impacts of invasive species and can be easily applied and adapted to other large-scale ecosystem projects.

Water Uptake Patterns of an Invasive Exotic Plant in Coastal Saline Habitats

Schinus terebinthifolius Raddi (Schinus) is one of the most widely found woody exotic species in South Florida. This exotic is distributed across environments with different hydrologic regimes, from upland pine forests to the edges of sawgrass marshes and into saline mangrove forests. To determine if this invasive exotic had different physiological attributes compared to native species in a coastal habitat, we measured predawn xylem water potentials (Ψ), oxygen stable isotope signatures (δ18O), and sodium (Na+) and potassium (K+) contents of sap water from plants within: (1) a transition zone (between a mangrove forest and upland pineland) and (2) an upland pineland in Southwest Florida. Under dynamic salinity and hydrologic conditions, Ψ of Schinus appeared less subject to fluctuations caused by seasonality when compared with native species. Although stem water δ18O values could not be used to distinguish the depth of Schinus and native species' water uptake in the transition zone, Ψ and sap Na+/K+ patterns showed that Schinus was less of a salt excluder relative to the native upland species during the dry season. This exotic also exhibited Na+/K+ ratios similar to the mangrove species, indicating some salinity tolerance. In the upland pineland, Schinus water uptake patterns were not significantly different from those of native species. Differences between Schinus and native upland species, however, may provide this exotic an advantage over native species within mangrove transition zones.

A search for an exotic meson in the gamma + P decaying to delta++ + pi- + eta reaction

A Partial Waves Analysis (PWA) of γp → Δ ++X → pπ+ π - (η) data taken with the CLAS detector at Jefferson Lab is presented in this work. This reaction is of interest because the Δ++ restricts the isospin of the possible X states, leaving the PWA with a smaller combination of partial waves, making it ideal to look for exotic mesons. It was proposed by Isgur and Paton that photoproduction is a plausible source for the Jpc=1–+ state through flux tube excitation. The π1(1400) is such a state that has been produced with the use of hadron production but it has yet to be seen in photoproduction. A mass independent amplitude analysis of this channel was performed, followed by a mass dependent fit to extract the resonance parameters. The procedure used an event-based maximum likelihood method to maintain all correlations in the kinematics. The intensity and phase motion is mapped out for the contributing signals without requiring assumptions about the underlying processes. The strength of the PWA is in the analysis of the phase motion, which for resonance behavior is well defined. In the data presented, the ηπ– invariant mass spectrum shows contributions from the a0(980) and a2(1320) partial waves. No π1 was observed under a clear a2 signal after the angular distributions of the decay products were analyzed using an amplitude analysis. In addition, this dissertation discusses trends in the data, along with the implemented techniques.

Disturbance regime and limits on benefits of refuge use for fishes in a fluctuating hydroscape

Refuge habitats increase survival rate and recovery time of populations experiencing environmental disturbance, but limits on the ability of refuges to buffer communities are poorly understood. We hypothesized that importance of refuges in preventing population declines and alteration in community structure has a non-linear relationship with severity of disturbance. In the Florida Everglades, alligator ponds are used as refuge habitat by fishes during seasonal drying of marsh habitats. Using an 11-year record of hydrological conditions and fish abundance in 10 marshes and 34 alligator ponds from two regions of the Everglades, we sought to characterize patterns of refuge use and temporal dynamics of fish abundance and community structure across changing intensity, duration, and frequency of drought disturbance. Abundance in alligator ponds was positively related to refuge size, distance from alternative refugia (e.g. canals), and abundance in surrounding marsh prior to hydrologic disturbance. Variables negatively related to abundance in alligator ponds included water level in surrounding marsh and abundance of disturbance-tolerant species. Refuge community structure did not differ between regions because the same subset of species in both regions used alligator ponds during droughts. When time between disturbances was short, fish abundance declined in marshes, and in the region with the most spatially extensive pattern of disturbance, community structure was altered in both marshes and alligator ponds because of an increased proportion of species more resistant to disturbance. These changes in community structure were associated with increases in both duration and frequency of hydrologic disturbance. Use of refuge habitat had a modal relationship with severity of disturbance regime. Spatial patterns of response suggest that decline in refuge use was because of decreased effectiveness of refuge habitat in reducing mortality and providing sufficient time for recovery for fish communities experiencing reduced time between disturbance events.

Book Review: Tourism in China: Exotic Land Revealed

There is no better way to lean about tourism in China than from renowned expert in the field. Alan Lew. PhD. and professor at Northern Arizona University, Lawrence Yu, Ph.D. and associate professor in the Department of Tourism and Hospitality Management at George Washington University. John Ap, Ph.D. and associate professor in tourism management at Hong Kong Polytechnic University and Zhang Guangrui, director of the Tourism Research Centre, Chinese Academy of Social Sciences in Beijing, China, have contributed to and edited a collection of writings detailing the development of tourism in this fascinating and exotic land.

A Tale of Two Fishes: Using Recreational Angler Records to Examine the Link Between Fish Catches and Floodplain Connections in a Subtropical Coastal River

In the tropical and subtropical wet and dry regions, maintaining natural hydrologic connections between coastal rivers and adjacent ephemeral wetlands is critical to conserving and sustaining high levels of fisheries production within these systems. Though there is a consensus that there is a need to maintain these natural connections, little is known about what attributes of floodplain inundation regimes are most important in sustaining fisheries production. Two attributes of the flood season and thus floodplain inundation that may be particularly influential to fisheries are the amplitude of the flood season (floodplain water depth and spatial extent of inundation) and the duration of the flood season (i.e., time floodplains are inundated). In mangrove-dominated Everglades coastal rivers, seasonal inundation of upstream marsh floodplains may play an important role in provisioning recreational fisheries; however, this relationship remains unknown. Using two Everglades coastal river fisheries as a model, we tested whether the amplitude of the flood season or the duration of the flood season is more important in explaining variation in angler catch records of common snook and largemouth bass collected from 1992 to 2012. We validated angler catches with fisheries-independent electrofishing conducted in the same region from 2004 to 2012. Our results showed (1) that bass angler catches tracked electrofishing catches, while snook catches were completely mismatched. And (2) that previous year's marsh dynamics, particularly the duration of the flood season, was more influential than the flood season amplitude in explaining variation in bass catches, such that bass angler catches were negatively correlated to the period time that floodplains remained disconnected from coastal rivers in the previous year, while snook catches were not very well explained by floodplain inundation terms.

Fish Community Responses to the Combined Effects of Decreased Hydroperiod and Nonnative Fish Invasions in a Karst Wetland: Are Everglades Solution Holes Sinks for Native Fishes?

Short-hydroperiod Everglades wetlands have been disproportionately affected by reductions in freshwater inflows, land conversion and biotic invasions. Severe hydroperiod reductions in these habitats, including the Rocky Glades, coupled with proximity to canals that act as sources of invasions, may limit their ability to support high levels of aquatic production. We examined whether karst solution holes function as dry-down refuges for fishes, providing a source of marsh colonists upon reflooding, by tracking fish abundance, nonnative composition, and survival in solution holes throughout the dry season. We paired field surveys with an in situ nonnative predation experiment that tested the effects of predation by the recent invader, African jewelfish (Hemichromis letourneuxi) on native fishes. Over the 3 years surveyed, a large number of the solution holes dried before the onset of the wet season, while those retaining water had low survivorship and were dominated by nonnatives. In the experiment, mortality of eastern mosquitofish (Gambusia holbrooki) in the presence of African jewelfish was greater than that associated with deteriorating water quality. Under current water management, findings suggest that solution holes are largely sinks for native fishes, given the high frequency of drydown, extensive period of fish residence, and predation by nonnative fishes.

Turning Passive Detection Systems into Field Experiments: An Application Using Wetland Fishes and Enclosures to Track Fine-Scale Movement and Habitat Choice

Understanding habitat selection and movement remains a key question in behavioral ecology. Yet, obtaining a sufficiently high spatiotemporal resolution of the movement paths of organisms remains a major challenge, despite recent technological advances. Observing fine-scale movement and habitat choice decisions in the field can prove to be difficult and expensive, particularly in expansive habitats such as wetlands. We describe the application of passive integrated transponder (PIT) systems to field enclosures for tracking detailed fish behaviors in an experimental setting. PIT systems have been applied to habitats with clear passageways, at fixed locations or in controlled laboratory and mesocosm settings, but their use in unconfined habitats and field-based experimental setups remains limited. In an Everglades enclosure, we continuously tracked the movement and habitat use of PIT-tagged centrarchids across three habitats of varying depth and complexity using multiple flatbed antennas for 14 days. Fish used all three habitats, with marked species-specific diel movement patterns across habitats, and short-lived movements that would be likely missed by other tracking techniques. Findings suggest that the application of PIT systems to field enclosures can be an insightful approach for gaining continuous, undisturbed and detailed movement data in unconfined habitats, and for experimentally manipulating both internal and external drivers of these behaviors.

Changes of Soil Biogeochemistry under Native and Exotic Plants Species

Invasive plant species are major threats to the biodiversity and ecosystem stability. The purpose of this study is to understand the impacts of invasive plants on soil nutrient cycling and ecological functions. Soil samples were collected from rhizosphere and non-rhizosphere of both native and exotic plants from three genera, Lantana, Ficus and Schinus, at Tree Tops Park in South Florida, USA. Experimental results showed that the cultivable bacterial population in the soil under Brazilian pepper (invasive Schinus) was approximately ten times greater than all other plants. Also, Brazilian pepper lived under conditions of significantly lower available phosphorus but higher phosphatase activities than other sampled sites. Moreover, the respiration rates and soil macronutrients in rhizosphere soils of exotic plants were significantly higher than those of the natives (Phosphorus, p=0.034; Total Nitrogen, p=0.0067; Total Carbon, p=0.0243). Overall, the soil biogeochemical status under invasive plants was different from those of the natives.