Susceptibility of Florida Aedes aegypti and Aedes albopictus to dengue viruses from Puerto Rico

Locally acquired dengue cases in the continental U.S. are rare. However, outbreaks of dengue‐1 during 2009, 2010, and 2013 in Florida and dengue‐1 and −2 in Texas suggest vulnerability to transmission. Travel and commerce between Puerto Rico and the U.S. mainland is common, which may pose a risk for traveler‐imported dengue cases. Mosquitoes were collected in Florida and used to evaluate their susceptibility to dengue viruses (DENV) from Puerto Rico. Aedes aegypti and Ae. albopictus were susceptible to virus infection with DENV‐1 and −2. No significant differences were observed in rates of midgut infection or dissemination between Ae. aegypti or Ae. albopictus for DENV‐1 (6–14%). Aedes aegypti was significantly more susceptible to midgut infection with DENV‐2 than Ae. albopictus (Ae. aegypti, ∼28%; Ae. albopictus, ∼9%). The dissemination rate with dengue‐2 virus for Ae. aegypti (23%) was greater than Ae. albopictus (0%), suggesting that Ae. albopictus is not likely to be an important transmitter of the DENV‐2 isolate from Puerto Rico. These results are discussed in light of Florida's vulnerability to DENV transmission.     

The impact of acidification on Chironomidae (Diptera) as indicated by subfossil stratification

The impact of acidification on the chironomid profundal fauna was studied by comparing chironomid head capsule deposits from different sediment layers. The 14–15 cm level was regarded as relatively unaffected by acid precipitation and therefore used as a control. The total number of capsules decreased, especially the number of Tanytarsinii capsules, from deeper to more superficial layers. Phaenopsectra and Psectrocladius showed a relative increase towards the surface level of the sediment. Probable causes for these changes are discussed.     

Vegetation:environment relationships and water management in Shark Slough,Everglades National Park

The hydrologic regime of Shark Slough, the most extensive long hydroperiod marsh in Everglades National Park, is largely controlled by the location, volume, and timing of water delivered to it through several control structures from Water Conservation Areas north of the Park. Where natural or anthropogenic barriers to water flow are present, water management practices in this highly regulated system may result in an uneven distribution of water in the marsh, which may impact regional vegetation patterns. In this paper, we use data from 569 sampling locations along five cross-Slough transects to examine regional vegetation distribution, and to test and describe the association of marsh vegetation with several hydrologic and edaphic parameters. Analysis of vegetation:environment relationships yielded estimates of both mean and variance in soil depth, as well as annual hydroperiod, mean water depth, and 30-day maximum water depth within each cover type during the 1990's. We found that rank abundances of the three major marsh cover types (Tall Sawgrass, Sparse Sawgrass, and Spikerush Marsh) were identical in all portions of Shark Slough, but regional trends in the relative abundance of individual communities were present. Analysis also indicated clear and consistent differences in the hydrologic regime of three marsh cover types, with hydroperiod and water depths increasing in the order Tall Sawgrass < Sparse Sawgrass < Spikerush Marsh. In contrast, soil depth decreased in the same order. Locally, these differences were quite subtle; within a management unit of Shark Slough, mean annual values for the two water depth parameters varied less than 15 cm among types, and hydroperiods varied by 65 days or less. More significantly, regional variation in hydrology equaled or exceeded the variation attributable to cover type within a small area. For instance, estimated hydroperiods for Tall Sawgrass in Northern Shark Slough were longer than for Spikerush Marsh in any of the other regions. Although some of this regional variation may reflect a natural gradient within the Slough, a large proportion is the result of compartmentalization due to current water management practices within the marsh. We conclude that hydroperiod or water depth are the most important influences on vegetation within management units, and attribute larger scale differences in vegetation pattern to the interactions among soil development, hydrology and fire regime in this pivotal portion of Everglades.     

Radium in the Suwannee River and estuary

A two-year study of radium in the Suwannee River has shown that groundwater discharge, via springs, is a very important source of radium both to the river and to offshore Gulf of Mexico waters. Dissolved radium is maintained within relatively narrow limits in the river by uptake into suspended particles. In the estuary, dissolved radium versus salinity profiles show distinctive nonconservative behavior with radium in significant excess of its linear mixing value at mid-salinities. Unlike the situation in many other estuaries, however, desorption of radium from particles cannot account for most of the observed excess. Thus, the anomalously high radium characteristic of much of the west Florida shelf apparently does not have a riverine source. Direct effusion of high-radium groundwater into these coastal waters is thought to be the major supplier of radium, and perhaps other elements as well.     

Modeling the effect of fire on the demography of <Emphasis Type="Italic">Dicerandra frutescens</Emphasis> ssp. <Emphasis Type="Italic">frutescens</Emphasis> (Lamiaceae), an endangered plant endemic to Florida scrub

Managing populations, either for conservation, harvesting, or control, requires a mechanistic or semi-mechanistic understanding of population dynamics. Here, we investigate how time-since-fire affects demographic transitions in an endangered plant, Dicerandra frutescens ssp. frutescens (Lamiaceae), which is specialized to gaps created by fire. We used a hierarchical Bayesian model to estimate transition probabilities (i.e., the elements of population projection matrices) as a function of time-since-fire and random effects, from 13 years of data on marked individuals in five populations. Using a standard Bayesian criterion to compare models, we find that death becomes increasingly probable and progression increasingly improbable with time-since-fire. The magnitude of some of the time-since-fire effects is substantial: death is 3–5 times more likely for flowering plants >6 years versus 3–6 years post-fire, 3-step progression is almost 7 times less likely, and large flowering plants are more than 6 times more likely to stop flowering. These insights inspire new hypotheses about the underlying cause of decline with time-since-fire, and how it can be managed. Our approach can be used by others who wish to model the effect of an exogenous factor on demography, while rigorously accounting for uncertainty and variability. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Differential physiological responses to prey availability by the great egret and white Ibis

In long-lived species, the balance between the benefits of reproduction and the costs from reduced survival or productivity is particularly challenging in dynamic environments like wetlands, where food levels vary greatly year to year. Some wetland species exhibit changes in reproductive strategies in response to food availability but whether physiological responses function in a similar manner is unclear. We compared the pre-breeding physiological responses (fecal corticosterone [FCORT], heat shock protein 60 [HSP60], and mass) of 2 species of wading birds with contrasting foraging strategies (great egret [Ardea alba], an exploiter, and white ibis [Eudocimus albus], a searcher) during years with contrasting levels of prey availability. Both species were in good physiological condition, with low levels of HSP60 and FCORT, during a year with high prey availability (2006). In a contrasting year with lesser prey availability (2007), HSP60 and FCORT concentrations indicated that ibis physiological condition was reduced, whereas egrets showed little change. Egrets and male ibis increased body mass, whereas female ibis decreased mass, in the year with low prey availability. Although poorly understood, we hypothesize that the differential response between female ibis and the others is associated with differential investment strategies based on long-term costs of reproduction. Model results identified prey availability and the 2-week water recession rate as the primary habitat variables that were associated with the physiological condition of white ibises, whereas great egret physiological condition was influenced mostly by 2-week water recession rate. Our results support the hypothesis that prey availability and hydrological factors play crucial roles in regulating populations of wading birds in the Florida Everglades. The results of this study show a more complete pathway by which hydrologic patterns affect wading birds, and it suggests that ibis are more sensitive to habitat conditions than are egrets. This information can be used to refine species models designed to evaluate water management scenarios and will improve our ability to manage and restore wetland ecosystems © 2012 The Wildlife Society.     

Spatial patch occupancy patterns of the Lower Keys marsh rabbit

Reliable estimates of presence or absence of a species can provide substantial information on management questions related to distribution and habitat use but should incorporate the probability of detection to reduce bias. We surveyed for the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) in habitat patches on 5 Florida Key islands, USA, to estimate occupancy and detection probabilities. We derived detection probabilities using spatial replication of plots and evaluated hypotheses that patch location (coastal or interior) and patch size influence occupancy and detection. Results demonstrate that detection probability, given rabbits were present, was <0.5 and suggest that naïve estimates (i.e., estimates without consideration of imperfect detection) of patch occupancy are negatively biased. We found that patch size and location influenced probability of occupancy but not detection. Our findings will be used by Refuge managers to evaluate population trends of Lower Keys marsh rabbits from historical data and to guide management decisions for species recovery. The sampling and analytical methods we used may be useful for researchers and managers of other endangered lagomorphs and cryptic or fossorial animals occupying diverse habitats. © 2011 The Wildlife Society.     

A new species of Perinereis (Polychaeta,Nereididae) from Florida,USA, with a key to all Perinereis from the?American continent

Specimens belonging to a new species of Perinereis Kinberg, 1865 were collected fromnatural oyster reefs in an estuarine environmenton Florida’s southwest coast. The genus Perinereis includes more than 70 species, of which, Perinereis aibuhitensis (Grube, 1878), Perinereis brevicirrata (Treadwell, 1920), Perinereis camiguinoides (Augener, 1922), Perinereis jascooki Gibbs, 1972, Perinereis kuwaitensis Mohammad, 1970, Perinereis singaporiensis (Grube, 1878), Perinereis vancaurica (Ehlers, 1868) and the new species have two short bars on Area VI and notopodial dorsal ligules that are not greatly expanded. The most geographically close species is Perinereis brevicirrata. The new species can be distinguished from Perinereis brevicirrata by the absence of a notopodial prechaetal lobe, Area V with 3 cones in a triangle, and Area VII-VIII with two well-defined rows of 33 paragnaths, the basal row having longer paragnaths in relation to the distal ones. The new species resembles Perinereis singaporiensis based on the absence of notopodial prechaetal lobe; however, the two species differ in some morphological characteristics such as tentacular cirri length, shape of dorsal notopodial ligules, and falciger blades. A key to all American species of Perinereis is included.     

Randomness or order in the occurrence and preservation of shallow-marine carbonate facies? Holocene, South Florida

This paper re-examines unsolved problems concerning the relationships between skeletal benthic communities, the skeletal carbonate sediments they produce and how these are preserved in the subsurface. Recent work based on shelf-wide datasets of modern shallow-marine carbonate sediments of South Florida suggest that the boundaries between facies occur randomly and that facies occurrence bears little relation to water depth. This is at variance with earlier work from the region that indicated facies occurrence related to different environments and which helped establish the basis for palaeoenvironmental analysis of ancient limestones.A windward-facing depositional margin of a carbonate mound in the back-reef area of the Florida Keys is used as a small-scale, case study to examine whether surface peritidal facies occur in an ordered or random fashion and whether they are depth related. Lateral facies transition analysis along transects from the shoreline to the shallow subtidal indicates that peritidal facies occur in a very well-ordered (i.e. non-random) arrangement of zones and patches. Surface facies are generally well-preserved and recognisable in the shallow subsurface and in cores through the Holocene carbonates and shoreline mangrove peats. Analysis of upward facies transitions in cores also indicates common facies trends reflecting the evolution of the sediment mound in response to rising Holocene sea level. However, even though the modern facies occur in an ordered and depth-related pattern, subsurface facies do not show a simple relation to the known sea-level curve in the area. Rather, they relate to a complex of different rates of sea-level rise, sea-floor topography, carbonate production rates, wave/storm energy input, and bioturbation.     

Restoration of Northwest Florida Sandhills Through Harvest of Invasive Pinus clausa

Across much of the southeastern U.S.A., sandhills have become dominated by hardwoods or invasive pine species following logging of Pinus palustris (longleaf pine) and fire suppression. At Eglin Air Force Base where this study was conducted, Pinus clausa (sand pine) has densely colonized most southeastern sandhill sites, suppressing groundcover vegetation. The objectives of this study were: to determine if suppressed groundcover vegetation recovers following the removal of P. clausa; to compare species composition and abundance in removal plots with that in reference, high quality sandhills; to test the assumption that recolonization by P. clausa seedlings decreases with proximity to the centers of removal plots; and to measure the survival of containerized P. palustris seedlings that were planted on P. clausa removal plots. One year post‐removal (1995), the number of plant species decreased by 50%, but then increased by 100% from 1995 to 1997, followed by a small reduction in 1998. The number of plant species was greater in reference plots than in removal plots prior to 1997. Eighty‐five percent of the original species were recorded 4 years post‐harvest in removal plots. Shrubs and large trees remained at low density after harvest. Densities of graminoids, legumes, other forbs, woody vines, and small trees increased after harvest. Plant densities of all life forms, except woody vines, were greater in reference plots than in removal plots. The density of recolonizing P. clausa seedlings 2–4 years post‐harvest significantly decreased with increasing proximity to the centers of removal plots. On average, 80% of planted P. palustris seedlings survived their first 2 years. Harvest of P. clausa followed by fire and the planting of P. palustris is a reasonably effective restoration approach in invaded sandhills. However, supplementary plantings of some herbaceous species may be necessary for full restoration.