Morphology and vocalization comparison of the Houston Toad and the Dwarf American Toad: implications for their historic range.

Documenting changes in the distribution and abundance of a given taxon requires historical data. In the absence of long-term monitoring data collected throughout the range of a taxon, conservation biologists often rely on preserved museum specimens to determine the past or present, putative geographic distribution. Distributional data for the Houston Toad (Anaxyrus houstonensis) has consistently been confounded by similarities with a sympatric congener, the Dwarf American Toad (A. americanus charlesmithi), both in monitoring data derived from chorusing surveys, and in historical data via museum specimens. In this case, misidentification can have unintended impacts on conservation efforts, where the Houston Toad is federally endangered, and the Dwarf American Toad is of least concern. Previously published reports have compared these two taxon on the basis of their male advertisement call and morphological appearance, often with the goal of using these characters to substantiate their taxonomic status prior to the advent of DNA sequencing technology. However, numerous studies report findings that contradict one another, and no consensus on the true differences or similarities can be drawn. Here, we use contemporary recordings of wild populations of each taxon to test for quantifiable differences in male advertisement call. Additionally, we quantitatively examine a subset of vouchered museum specimens representing each taxon to test previously reported differentiating morphometric characters used to distinguish among other Bufonids of East-Central Texas, USA. Finally, we assemble and qualitatively evaluate a database of photographs representing catalogued museum vouchers for each taxon to determine if their previously documented historic ranges may be larger than are currently accepted. Our findings reveal quantifiable differences between two allopatric congeners with respect to their male advertisement call, whereas we found similarities among their detailed morphology. Additionally, we report on the existence of additional, historically overlooked, museum records for the Houston Toad in the context of its putative historic range, and discuss errors associated with the curation of these specimens whose identity and nomenclature have not been consistent through time. These results bookend decades of disagreement regarding the morphology, voice, and historic distribution of these taxa, and alert practitioners of conservation efforts for the Houston Toad to previously unreported locations of occurrence.

Using genome-wide data to ascertain taxonomic status and assess population genetic structure for Houston toads (Bufo [= Anaxyrus] houstonensis).

The Houston toad (Bufo [= Anaxyrus] houstonensis) is an endangered amphibian with a small geographic range. Land-use changes have primarily driven decline in B. houstonensis with population supplementation predominant among efforts to reduce its current extinction risk. However, there has been historic uncertainty regarding the evolutionary and conservation significance of B. houstonensis. To this end, we used 1170 genome-wide nuclear DNA markers to examine phylogenetic relationships between our focal taxon, representatives of the Nearctic B. americanus group, and B. nebulifer, a sympatric Middle American species. Phylogenetic analyses indicate B. houstonensis is a taxon that is distinct from B. americanus. We corroborated such genetic distinctiveness with an admixture analysis that provided support for recent reproductive isolation between B. americanus and B. houstonensis. However, ABBA-BABA tests for ancient admixture indicated historic gene flow between Nearctic species while no signal of historic gene flow was detected between Nearctic and Middle-American species. We used an admixture analysis to recognize four Management Units (MU) based on observed genetic differentiation within B. houstonensis and recommend captive propagation, population supplementation, and habitat restoration efforts specific to each MU. Our results re-affirm the evolutionary novelty of an endangered relict.

Patterns of genetic divergence in the Rio Grande cooter (Pseudemys gorzugi), a riverine turtle inhabiting an arid and anthropogenically modified system.

The lower Rio Grande and Pecos River of the southwest United States have been heavily modified by human activities, profoundly impacting the integrity of their aquatic wildlife. In this context, we focused our study on the population genomics of the Rio Grande Cooter (Pseudemys gorzugi), a freshwater turtle of increasing conservation concern, residing in these two rivers and their tributaries. The genetic data revealed two distinct populations: one in the Pecos and Black Rivers of New Mexico and another in the Rio Grande and Devils River of Texas, with admixed individuals identified at the confluence of the Rio Grande and Pecos River. In addition to having a smaller geographic range, we found lower observed heterozygosity, reduced nucleotide diversity, and a smaller effective population size (Ne) in New Mexico population. Our results depict a significant isolation-by-distance pattern across their distribution, with migration being notably infrequent at river confluences. These findings are pivotal for future conservation and restoration strategies, emphasizing the need to recognize the unique needs of each population.

Mitochondrial sequence data reveal population structure within Pustulosa pustulosa.

Unionid mussels are among the most imperiled group of organisms in North America, and Pustulosa pustulosa is a freshwater species with a relatively wide latitudinal distribution that extends from southern Ontario, Canada, to Texas, USA. Considerable morphological and geographic variation in the genus Pustulosa (formerly Cyclonaias) has led to uncertainty over species boundaries, and recent studies have suggested revisions to species-level classifications by synonymizing C. aurea, C. houstonensis, C. mortoni, and C. refulgens with C. pustulosa (currently P. pustulosa). Owing to its wide range and shallow phylogenetic differentiation, we analyzed individuals of P. pustulosa using mitochondrial DNA sequence data under a population genetics framework. We included 496 individuals, which were comprised of 166 samples collected during this study and 330 additional sequences retrieved from GenBank. Pairwise ΦST measures based on ND1 data suggested there may be up to five major geographic groups present within P. pustulosa. Genetic differentiation between regions within Texas was higher compared to populations from the Mississippi and Great Lakes populations, which may reflect differences in historical connectivity. Mitochondrial sequence data also revealed varying demographic histories for each major group suggesting each geographic region has also experienced differential population dynamics in the past. Future surveys should consider exploring variation within species after phylogeographic delimitation has been performed. In this study, we begin to address this need for freshwater mussels via the P. pustulosa system.

Development and validation of an environmental DNA assay to detect federally threatened groundwater salamanders in central Texas.

The molecular detection of DNA fragments that are shed into the environment (eDNA) has become an increasingly applied tool used to inventory biological communities and to perform targeted species surveys. This method is particularly useful in habitats where it is difficult or not practical to visually detect or trap the target organisms. Central Texas Eurycea salamanders inhabit both surface and subterranean aquatic environments. Subterranean surveys are challenging or infeasible, and the detection of salamander eDNA in water samples is an appealing survey technique for these situations. Here, we develop and validate an eDNA assay using quantitative PCR for E. chisholmensis, E. naufragia, and E. tonkawae. These three species are federally threatened and constitute the Septentriomolge clade that occurs in the northern segment of the Edwards Aquifer. First, we validated the specificity of the assay in silico and with DNA extracted from tissue samples of both target Septentriomolge and non-target amphibians that overlap in distribution. Then, we evaluated the sensitivity of the assay in two controls, one with salamander-positive water and one at field sites known to be occupied by Septentriomolge. For the salamander-positive control, the estimated probability of eDNA occurrence (ψ) was 0.981 (SE = 0.019), and the estimated probability of detecting eDNA in a qPCR replicate (p) was 0.981 (SE = 0.011). For the field control, the estimated probability of eDNA occurring at a site (ψ) was 0.938 (95% CRI: 0.714-0.998). The estimated probability of collecting eDNA in a water sample (θ) was positively correlated with salamander relative density and ranged from 0.371 (95% CRI: 0.201-0.561) to 0.999 (95% CRI: 0.850- > 0.999) among sampled sites. Therefore, sites with low salamander density require more water samples for eDNA evaluation, and we determined that our site with the lowest estimated θ would require seven water samples for the cumulative collection probability to exceed 0.95. The estimated probability of detecting eDNA in a qPCR replicate (p) was 0.882 (95% CRI: 0.807-0.936), and our assay required two qPCR replicates for the cumulative detection probability to exceed 0.95. In complementary visual encounter surveys, the estimated probability of salamanders occurring at a known-occupied site was 0.905 (SE = 0.096), and the estimated probability of detecting salamanders in a visual encounter survey was 0.925 (SE = 0.052). We additionally discuss future research needed to refine this method and understand its limitations before practical application and incorporation into formal survey protocols for these taxa.

Quantification of chlamydiae in the endangered Houston toad (Anaxyrus houstonensis).

Two primer set/probe combinations targeting variable regions on the 23S rRNA gene were designed to detect and quantify chlamydiae in DNA extracted from brain swabs of the endangered Houston toad (Anaxyrus houstonensis) using SYBRGreen- and Taqman-based quantitative polymerase chain reaction (qPCR). Prevalence and abundance values for samples were generally different between SYBRGreen- and Taqman-based detection methods, with higher specificity observed for Taqman-based detection. Of the 314 samples analyzed, initial screening with SYBRGreen-based qPCR retrieved 138 positive samples, of which 52 were confirmed by Taqman-based analyses as chlamydiae. All of these samples were subsequently identified as Chlamydia pneumoniae by specific qPCR and confirmed by comparative sequence analyses of 23S rRNA gene amplicons. These results demonstrate the usefulness of our developed qPCR methods to screen for and verify prevalence of chlamydiae in DNA of brain swabs, and ultimately specifically identify and quantify chlamydiae, specifically C. pneumoniae in these samples.

Animal Species Recognition with Deep Convolutional Neural Networks from Ecological Camera Trap Images.

Accurate identification of animal species is necessary to understand biodiversity richness, monitor endangered species, and study the impact of climate change on species distribution within a specific region. Camera traps represent a passive monitoring technique that generates millions of ecological images. The vast numbers of images drive automated ecological analysis as essential, given that manual assessment of large datasets is laborious, time-consuming, and expensive. Deep learning networks have been advanced in the last few years to solve object and species identification tasks in the computer vision domain, providing state-of-the-art results. In our work, we trained and tested machine learning models to classify three animal groups (snakes, lizards, and toads) from camera trap images. We experimented with two pretrained models, VGG16 and ResNet50, and a self-trained convolutional neural network (CNN-1) with varying CNN layers and augmentation parameters. For multiclassification, CNN-1 achieved 72% accuracy, whereas VGG16 reached 87%, and ResNet50 attained 86% accuracy. These results demonstrate that the transfer learning approach outperforms the self-trained model performance. The models showed promising results in identifying species, especially those with challenging body sizes and vegetation.

Effects of salinization on the occurrence of a long-lived vertebrate in a desert river.

The lower Pecos River located in the southwest USA, is a naturally saline river system that has been significantly altered in relatively recent years. Climate change, coupled with anthropogenic disturbances such as dam construction have led to portions of the river becoming more susceptible to increased salinization and declines in water quality. These alterations have been documented to be detrimental to multiple freshwater communities; however, there is a lack of knowledge on how these alterations influence long-lived species in the river, such as freshwater turtles, where the effects can appear over dramatically different temporal scales. The Rio Grande Cooter (Pseudemys gorzugi) is a species of concern known to occur in the Pecos River. To understand the current distribution and habitat requirements for P. gorzugi in the Pecos River, we used a single-season, single-species occupancy modeling framework to estimate occurrence while accounting for the sampling process. Day of year, water surface area, and water visibility had the greatest influence on the ability to detect the species given a sampling unit is occupied. Conductivity (a measure of salinity) had the greatest influence on the occupancy probability for the species, where sites with higher conductivity coincided with lower occupancy probabilities. This study indicates that increased salinization on the lower Pecos River is a cause for concern regarding freshwater turtle populations within the Chihuahuan Desert.

Comparative host-pathogen associations of Snake Fungal Disease in sympatric species of water snakes (Nerodia).

The ascomycete fungus Ophidiomyces ophiodiicola (Oo) is the causative agent of ophidiomycosis (Snake Fungal Disease), which has been detected globally. However, surveillance efforts in the central U.S., specifically Texas, have been minimal. The threatened and rare Brazos water snake (Nerodia harteri harteri) is one of the most range restricted snakes in the U.S. and is sympatric with two wide-ranging congeners, Nerodia erythrogaster transversa and Nerodia rhombifer, in north central Texas; thus, providing an opportunity to test comparative host-pathogen associations in this system. To accomplish this, we surveyed a portion of the Brazos river drainage (~ 400 river km) over 29 months and tested 150 Nerodia individuals for the presence of Oo via quantitative PCR and recorded any potential signs of Oo infection. We found Oo was distributed across the entire range of N. h. harteri, Oo prevalence was 46% overall, and there was a significant association between Oo occurrence and signs of infection in our sample. Models indicated adults had a higher probability of Oo infection than juveniles and subadults, and adult N. h. harteri had a higher probability of infection than adult N. rhombifer but not higher than adult N. e. transversa. High Oo prevalence estimates (94.4%) in adult N. h. harteri has implications for their conservation and management owing to their patchy distribution, comparatively low genetic diversity, and threats from anthropogenic habitat modification.

Quantification of members of the Mycobacterium chelonae-abscessus complex in lesions of the endangered houston toad (Anaxyrus houstonensis).

Illumina-based 16S rRNA V3 amplicon sequencing of total DNA obtained from soft tissue lesions (joint granulomas) of the endangered Houston toad (Anaxyrus houstonensis) demonstrated that many reads represented members of the actinobacterial Mycobacterium chelonae-abscessus complex. In order to quantify members of this complex in those lesions, we designed three complex-specific primer set/probe combinations (sets I, II and III) targeting variable regions on the 23S rRNA gene for SybrGreen- and Taqman-based quantitative polymerase chain reaction (qPCR). Both SybrGreen- and Taqman-based analyses specifically detected members of the M. chelonae-abscessus complex in lesion samples, with numbers between 104 and 107 cells per 100-mg sample. Values within individual samples were generally comparable between SybrGreen- and Taqman-based detection methods and between all primer set/probe combinations, except for SybrGreen-based analyses of a few samples analyzed with primer set I that used a less specific forward primer. The development of highly specific detection and quantification methods for members of the M. chelonae-abscessus complex in lesion samples can enable group specific tracking of these organisms, particularly in captive or stewardship settings where source and transmission monitoring are valuable tools to husbandry and species conservation.

Predicting surface abundance of federally threatened Jollyville Plateau Salamanders (Eurycea tonkawae) to inform management activities at a highly modified urban spring.

Urban expansion has contributed to the loss of habitat for range restricted species across the globe. Managing wildlife populations within these urban settings presents the challenge of balancing human and wildlife needs. Jollyville Plateau Salamanders (Eurycea tonkawae) are a range restricted, federally threatened, species of neotenic brook salamander endemic to central Texas. Almost the entire geographic range of E. tonkawae is embedded in the Austin, Cedar Park, and Round Rock metropolitan areas of Travis and Williamson counties, Texas. Among E. tonkawae occupied sites, Brushy Creek Spring has experienced some of the most extensive anthropogenic disturbance. Today the site consists of small groundwater outlets that emerge in the seams within a concrete culvert underlying a highway. Salamanders persist within this system though they are rarely detected. Here, we model the occurrence of salamanders within the surface habitat of Brushy Creek Spring using generalized linear models. In the absence of available data regarding the amount of water that is discharged from the spring, we use accumulated rainfall as a proxy for discharge to estimate salamander abundance. Additionally, we present evidence of reproduction, recruitment, and subterranean movement by E. tonkawae throughout this site. Infrastructure maintenance is inevitable at Brushy Creek Spring. We intend for our results to inform when maintenance should occur, i.e., during environmental conditions when salamanders are less likely to be observed in the surface habitat, to avoid unnecessary impacts to this federally threatened species.

Comparative Benefit-Risk Assessment for Lidocaine 700 mg Medicated Plaster and Pregabalin in Peripheral Neuropathic Pain Following a Structured Framework Approach.

INTRODUCTION: Peripheral neuropathic pain (PNP) is difficult to treat. Several oral drugs are recommended as first-line treatments. Nevertheless, many patients cannot obtain sufficient pain relief or do not tolerate systemically active treatments. Topical treatments, with a lower risk of systemic side effects such as lidocaine 700 mg medicated plaster, are also recommended in treatment guidelines. This analysis compares the benefit-risk balance of topical 700 mg lidocaine medicated plaster with the benefit-risk balance of oral pregabalin administration for the treatment of PNP following current recommendations on benefit-risk assessment (BRA) methodology. METHODS: The Benefit-Risk Action Team (BRAT) framework was used as structured approach. Selection of key benefits and risks was supported by a patient survey. Published randomized controlled clinical trials were the main source to identify data related to key benefits and risks. The outcome of randomized clinical trials was compared with real-world evidence (RWE) data for consistency. RESULTS: Identified key benefits were pain reduction and improvement in quality of life. Key risks identified were application site reactions, dizziness, confusion, weight gain, peripheral edema, and blurred vision. Overall, there was similarity in key benefits between the comparators; however, a clear advantage regarding key risks in favor of lidocaine 700 mg medicated plaster was observed. This observation was consistent across data from a direct comparison trial, randomized placebo-controlled trials, as well as data from RWE studies. The low number of randomized controlled trials for lidocaine 700 mg medicated plaster was the main limitation. CONCLUSION: Guided by the opinion of patients regarding key benefits and risks deemed important for treatments of peripheral neuropathic pain, our analysis showed that lidocaine 700 mg medicated plaster has a more favorable benefit-risk balance compared to pregabalin (300 and 600 mg daily).

Environmental determinants of Batrachochytrium dendrobatidis and the likelihood of further dispersion in the face of climate change in Texas, USA.

One of the major drivers of amphibian population declines is Batrachochytrium dendrobatidis (Bd). We sought to identify the major environmental drivers of Bd prevalence in Texas, USA, by drawing results from museum specimens. We sampled one of the largest museum collections in Texas, the Biodiversity Research and Teaching Collections at Texas A&M University. Our sampling focused on the 9 amphibian species with the widest geographical distribution within the state, where we sub-sampled 30% of each species per decade from 1930 to present via skin swabs, totaling 1501 independent sampling events, and used quantitative real-time PCR (qPCR) to detect pathogen presence. We analyzed several geo-referenced variables describing climatic conditions to identify potential factors influencing the likelihood of presence of Bd using boosted regression trees. Our final model suggests the most influential variables are mean temperature of driest quarter, annual mean temperature, temperature annual range, and mean diurnal range. The most likely suitable range for Bd is currently found in the Blackland Prairie and Cross Timbers ecoregions. Results of our future (to the year 2040) projections suggest that Bd could expand its current distribution. Our model could play an important role when developing an integrated conservation plan through (1) focusing future field work on locations with a high likelihood of presence, (2) assisting in the choice of locations for restoration, and (3) developing future research plans including those necessary for projecting reactions to climate change. Our model also could integrate new presence data of Bd when they become available to enhance prediction precision.

Optimizing the power of human performed audio surveys for monitoring the endangered Houston toad using automated recording devices.

Knowledge regarding the locations of populations of endangered species is a critical part of recovery and facilitates land use planning that avoids unnecessary impacts. Regulatory agencies often support the development of survey guidelines designed to standardize the methods and maximize the probability of detection, thereby avoiding incorrectly concluding a species is absent from a site. Here, using simulations with data collected using automated recording devices (ARDs) we evaluated the efficacy of the existing U.S. Fish and Wildlife Service's survey requirements for the endangered Houston Toad (Anaxyrus houstonensis). We explored the effect of (1) increasing survey duration, (2) increasing the number of surveys, and (3) combinations of environmental conditions (e.g., temperature, humidity, rainfall) on the detection probability and the number of surveys needed to be 95% confident of absence. We found that increases in both the duration of the survey and the number of surveys conducted decreased the likelihood of incorrectly concluding the species was absent from the site, and that the number of surveys required to be 95% confident greatly exceeded the existing survey requirements. Targeting specific environmental conditions was also an effective way to decrease the number of surveys required but the infrequency in which these conditions occurred might make application difficult in some years. Overall, we suggest that the survey effort necessary to achieve confidence in the absence of Houston Toads at a site is more practically achievable with the use of ARDs, but this may not be suitable in all monitoring scenarios.

Use of intravenous iron and risk of anaphylaxis: A multinational observational post-authorisation safety study in Europe.

PURPOSE: This post-authorisation safety study estimated the risk of anaphylaxis in patients receiving intravenous (IV) iron in Europe, with interest in iron dextran and iron non-dextrans. Studies conducted in the United States have reported risk of anaphylaxis to IV iron ranging from 2.0 to 6.8 per 10 000 first treatments. METHODS: Cohort study of IV iron new users, captured mostly through pharmacy ambulatory dispensing, from populations covered by health and administrative data sources in five European countries from 1999 to 2017. Anaphylaxis events were identified through an algorithm that used parenteral penicillin as a positive control. RESULTS: A total of 304 210 patients with a first IV iron treatment (6367 iron dextran), among whom 13-16 anaphylaxis cases were identified and reported as a range to comply with data protection regulations. The pooled unadjusted incidence proportion (IP) ranged from 0.4 (95% confidence interval [CI], 0.2-0.9) to 0.5 (95% CI, 0.3-1.0) per 10 000 first treatments. No events were identified at first dextran treatments. There were 231 294 first penicillin treatments with 30 potential cases of anaphylaxis (IP = 1.2; 95% CI, 0.8-1.7 per 10 000 treatments). CONCLUSION: We found an IP of anaphylaxis from 0.4 to 0.5 per 10 000 first IV iron treatments. The study captured only a fraction of IV iron treatments administered in hospitals, where most first treatments are likely to happen. Due to this limitation, the study could not exclude a differential risk of anaphylaxis between iron dextran and iron non-dextrans. The IP of anaphylaxis in users of penicillin was consistent with incidences reported in the literature.

Influence of landscape condition on relative abundance and body condition of two generalist freshwater turtle species.

Anthropogenic land use changes have broad impacts on biological diversity, often resulting in shifts in community composition. While many studies have documented negative impacts on occurrence and abundance of species, less attention has been given to native species that potentially benefit from anthropogenic land use changes. For many species reaching high densities in human-dominated landscapes, it is unclear whether these environments represent higher quality habitat than more natural environments. We examined the influence of landscape ecological integrity on relative abundance and body condition of two native generalist freshwater turtle species that are prevalent in anthropogenic systems, the painted turtle (Chrysemys picta) and red-eared slider (Trachemys scripta elegans). Relative abundance was negatively associated with ecological integrity for both species, but the relationship was not strongly supported for painted turtles. Body condition was positively associated with ecological integrity for painted turtles, with no strong association for red-eared sliders. Our study suggests that both species benefitted at the population level from reduced ecological integrity, but individual-level habitat quality was reduced for painted turtles. The differing responses between these two habitat generalists could partially explain why red-eared sliders have become a widespread exotic invasive species, while painted turtles have not.

MYCOBACTERIA IN SKIN LESIONS AND THE HABITAT OF THE ENDANGERED HOUSTON TOAD (ANAXYRUS HOUSTONENSIS).

Head-starting of the federally endangered Houston toad (Anaxyrus houstonensis), that is, the release of egg strands, tadpoles, and metamorphic juveniles produced in captivity into the original breeding ponds, requires assessment of potential threats for the transmission of pathogens from captive to free-ranging toads. We used Illumina-based 16S rRNA V3 amplicon sequencing to investigate the community structure of bacteria from skin lesions of captive Houston toad and habitat (pond) samples. Proteobacteria, alone or together with Actinobacteria and, in some samples, Cyanobacteria represented virtually all reads in tissue lesion samples, whereas pond samples were much more diverse, with Acidobacteria, Actinobacteria, Bacteriodetes, Chloroflexi, Cyanobacteria, Firmicutes, Planctomycetes, Proteobacteria, and Verrucomicrobia present with little variation between samples. If present in lesions, Actinobacteria were largely represented by Mycobacteriaceae, and here mainly by one sequence identical to sequences of members of the Mycobacterium chelonae-abscessus complex. In pond samples, mycobacteria represented only a small portion of the actinobacteria, although at higher diversity with six distinct reads. Sequences for reads obtained from pond samples were identical to those representing the M. chelonae-abscessus complex, a group with Mycobacterium marinum, Mycobacterium kansasii, Mycobacterium avium, a group with Mycobacterium vaccae, Mycobacterium fortuitum, Mycobacterium poriferae, and a group with Mycobacterium elephantis and Mycobacterium celeriflavum, whereas sequences of high similarity were detected for reads related to those of Mycobacterium holsaticum, Mycobacterium pallens, and Mycobacterium obuense, and Mycobacterium goodii. Our results indicated that lesions observed on the Houston toad in captivity are not the result of mycobacteria in every case, and that the presence of mycobacteria in the captive colony does not represent a novel pathogen threat to the wild populations because such bacteria are also seen in the natural pond habitats for the Houston toad.

Morphometric data for five freshwater turtles in south, central, and west Texas.

From 2008 to 2013, we sampled freshwater turtle populations at 66 sites in south, central, and west Texas, USA. Sampling sites included ponds, lakes, resacas (oxbow lakes), canals, and rivers. We sampled turtle populations using baited hoop nets (66 sites) and basking traps (3 sites), and captured turtles by hand opportunistically in terrestrial habitat. We measured carapace length and width, plastron length and width, body depth, and weight of captured turtles. Excluding recaptures, we measured 356 Apalone spinifera emoryi (Texas Spiny Softshell), 24 Chelydra serpentina (Snapping Turtle), 20 Kinosternon flavescens (Yellow Mud Turtle), 47 Trachemys gaigeae (Big Bend Slider), and 1070 Trachemys scripta elegans (Red-eared Slider). Carapace length of Apalone spinifera emoryi ranged from 85 to 426 mm (mean = 182 mm). Carapace length of Chelydra serpentina ranged from 74 to 320 mm (mean = 233 mm). Carapace length of Kinosternon flavescens ranged from 64 to 147 mm (mean = 114 mm). Carapace length of Trachemys gaigeae ranged from 54 to 203 mm (mean = 141 mm). Carapace length of Trachemys scripta elegans ranged from 30 to 328 mm (mean = 171 mm). These data are useful for assessing spatial and temporal variation in size and body condition of freshwater turtles.

Evaluating the effects of red imported fire ants (Solenopsis invicta) on juvenile Houston Toads (Bufo [=Anaxyrus] houstonensis) in Colorado County, TX.

The spread of invasive species is considered a major threat to biodiversity, second only to habitat loss. Red Imported Fire Ants (Solenopsis invicta) are a globally invasive species with negative impacts reported on native invertebrate and vertebrate species. Federally endangered Houston Toads (Bufo [=Anaxyrus] houstonensis), endemic to Texas, are among the vertebrates reportedly negatively impacted by Red Imported Fire Ants (RIFA). Threats posed by RIFA to Houston Toads needed to be explicitly characterized. Large-scale chemical treatments to suppress RIFA and facilitate brood survival in Attwater's prairie-chickens (Tympanuchus cupido attwateri) at the Attwater Prairie Chicken National Wildlife Refuge (APCNWR) afforded us an opportunity to experimentally examine the influence of RIFA abundance on juvenile Houston Toad growth and survival. We also sought to examine whether juvenile Houston Toads could grow and survive in a vegetation type similar to a historic species locality. We conducted a terrestrial mesocosm experiment to test whether the application of bait-driven suppressant decreased counts of RIFA relative to untreated sites. We examined whether counts of native ant and non-ant native invertebrates were higher in response to potential decreases in RIFA. We compared growth and survival rates in juvenile Houston Toads among treated and untreated sites, expecting juvenile growth and survival to be higher in response to potentially decreased RIFA counts and increased native invertebrate counts. We saw lower counts of RIFA in treated prairies, but we also observed a decrease in native ant counts possibly due to chemical treatment. Therefore, the application of bait-driven suppressant may not affect RIFA alone. We saw no difference in counts of non-ant invertebrates among treated and untreated sites. Juvenile Houston Toads did not differ in growth and survival among treated and untreated sites. We recognize that the lack of a relationship between juvenile growth and survival with a treatment effect, and therefore RIFA abundance, may be limited to APCNWR. We encourage additional experimental studies to elucidate RIFA impacts at other sites. We extrapolated apparent survival estimates from our study to one year. These appear comparable to juvenile survivorship required in simulations for Houston Toad population persistence and on this basis, we recommend that APCNWR be re-evaluated as a reintroduction site for Houston Toads. We also recommend further studies to potentially broaden the regulatory definition of Houston Toad habitat beyond the current restrictive view of canopied forest alone. Such studies would need to examine the utility of native grasslands as dispersal corridors/upland habitat for juvenile Houston Toads. Our findings emphasize the utility of experimental studies in directly examining the influence of perceived threats to imperiled species and the role of such clarifications in adapting recovery efforts.

Detection of Salmonella in the intestine of Hypostomus plecostomus from the upper San Marcos River, Texas.

The prevalence of salmonellae in the intestines of the invasive suckermouth catfish Hypostomus plecostomus was assessed in the San Marcos River, just down-stream of its spring-fed headwaters. In 2014, H. plecostomus, sediment, and water samples were collected during 15 sampling events. A combination of semi-selective enrichment and quantitative polymerase chain reaction (qPCR) revealed the presence of salmonellae in 45% of the fish intestines across the entire year, with a prevalence range of 13-100% per sampling event. Repetitive element sequence-based PCR (rep-PCR) and multi-locus sequence typing (MLST) revealed a high diversity of salmonellae from fish intestine samples at individual sampling times, single or multiple presence of rep-PCR patterns and serotypes within individual fish, and identical rep-PCR patterns and serotypes for different fish within and across sampling events. Overall, 15 serotypes were identified by MLST, with a diversity range between one and seven serotypes per sampling event. Some serotypes were retrieved only once, while others were detected more frequently. A few serotypes were retrieved at several sampling times, nearly evenly distributed over the entire sampling period. Prevalence and diversity were independent of precipitation events, indicating the potential presence of environmental strains that are capable of long-term persistence in the environment.