1,720,982 research outputs found
Movement and Habitat Use of Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) Following Population Augmentation
No full textMccallen, Emily B., Kraus, Bart T., Burgmeier, Nick G., Fei, Songlin, Williams, Rod N., . (2018): Movement and Habitat Use of Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) Following Population Augmentation. Herpetologica 74, No. 4: 283-293, DOI: 10.1655/0018-0831.28
FIG. 3 in Movement and Habitat Use of Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) Following Population Augmentation
No full textFIG. 3.—Mean monthly linear home range size (±1 SE) of resident and translocated adult Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) at two sites in the Blue River in Indiana over four seasons following population augmentation.Published as part of Mccallen, Emily B., Kraus, Bart T., Burgmeier, Nick G., Fei, Songlin, Williams, Rod N. & ., 2018, Movement and Habitat Use of Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) Following Population Augmentation, pp. 283-293 in Herpetologica 74 on page 289, DOI: 10.1655/0018-0831.283, http://zenodo.org/record/771687
FIG. 1 in Movement and Habitat Use of Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) Following Population Augmentation
No full textFIG. 1.—Dispersal distances of Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) in the Blue River in Indiana. Zero represents the point of release, positive values reflect upstream movements, and negative values reflect downstream movements. (A) Resident and wild translocated subjects at Site 1; (B) resident and captive-reared translocated subjects at Site 2.Published as part of Mccallen, Emily B., Kraus, Bart T., Burgmeier, Nick G., Fei, Songlin, Williams, Rod N. & ., 2018, Movement and Habitat Use of Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) Following Population Augmentation, pp. 283-293 in Herpetologica 74 on page 288, DOI: 10.1655/0018-0831.283, http://zenodo.org/record/771687
FIG. 4 in Movement and Habitat Use of Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) Following Population Augmentation
No full textFIG. 4.—Mean probability (±1 SE) of artificial nest rock (ANR) use for wild resident adult, captive-reared translocated juvenile, and wild translocated adult Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) at two sites in the Blue River in Indiana.Published as part of Mccallen, Emily B., Kraus, Bart T., Burgmeier, Nick G., Fei, Songlin, Williams, Rod N. & ., 2018, Movement and Habitat Use of Eastern Hellbenders (Crŋptobranchus alleganiensis alleganiensis) Following Population Augmentation, pp. 283-293 in Herpetologica 74 on page 290, DOI: 10.1655/0018-0831.283, http://zenodo.org/record/771687
Detection and survival rates for the eastern hellbender ( Cryptobranchus alleganiensis alleganiensis) in the Blue River, Indiana
No full textThe Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis ) is a large, fully aquatic salamander that inhabits clean, cool, well-oxygenated rivers and streams of the Eastern and Midwestern United States. Eastern Hellbenders occupy higher trophic levels within lotic ecosystems and are believed to regulate and maintain aquatic invertebrate communities. However, Eastern Hellbender populations have suffered precipitous declines throughout their range over the last three to four decades. The Midwestern United States, in particular, have experienced severe Eastern Hellbender population declines. In Indiana, recent empirical data indicate Eastern Hellbender densities are much lower than historical estimates and that the population consists of older adults with little to no spatial overlap. State and federal agencies are now focusing on captive-rearing and translocation efforts for juvenile and adult Eastern Hellbenders to supplement existing populations. To track the success of these efforts, individuals are often marked with passive integrated transponder (PIT) tags. This ensures that individuals can be identified during surveys to monitor populations. However, traditional survey methods can damage habitat, especially nesting habitat, which can cause abandonment. I sought to: 1) determine the efficacy of using a PIT tag scanner to detect marked Eastern Hellbenders under limestone boulders, 2) compare the effectiveness of PIT tag surveys to radio-telemetry and rock-lifting and snorkeling surveys, and 3) estimate survival rates using a known-fates model to evaluate the efficacy of translocating captive-reared juvenile and wild adult Eastern Hellbenders. Specifically, I wanted to estimate survival rates, determine whether survival rates were significantly different between resident adults and translocated adults, and relate potential explanatory variables to the survival rates. Rock thickness detection tests revealed the PIT tag reader and antenna could detect a 23.0 mm PIT tag under rocks nearly twice as thick (i.e., 35.6 cm versus 19.2cm) compared to a 12.5 mm PIT tag. Detectability surveys conducted by naïve surveyors exhibited considerable variation in detection and CPUE. The duration of radio-telemetry was 1.9 person-hours and resulted in 100.0% detection and a catch per unit effort (CPUE) of 9.6 Eastern Hellbenders/person-hour. The duration of PIT tag scanning was 5.3 person-hours and resulted in 33.3% detection and a CPUE of 1.1 Eastern Hellbenders/person-hour. The duration of rock-lifting and snorkel sampling was 51.5 person-hours and resulted in 38.9% detection and a CPUE of 0.1 Eastern Hellbenders/person-hour. Radio-telemetry detection was higher than both PIT tag scanning and rock-lifting and snorkel surveys. PIT tag scanning detection was comparable to rock-lifting and snorkel sampling, but was an order of magnitude more efficient in CPUE. Cox proportional hazard models indicated differential survival rates when all 42 individuals were included in the analysis, age class was the only significant explanatory variable (i.e., adults had higher survival). Survival rates did not vary depending on resident status or site location. The overall survival rate was 0.60 and ranged from 0.23 (juveniles) to 0.82 (adult males). Adult male Eastern Hellbenders had higher annual survival than adult females (0.82 vs. 0.65), although the difference in survival rates was not statistically significant. There were no significant differences in survival rates between resident adults and translocated adults at either study site. This study: 1) demonstrates the effectiveness and potential utility of PIT tag technology for surveying and monitoring marked Eastern Hellbenders in a less invasive manner than traditional survey methods, 2) provides baseline survival data for captive-reared juvenile Eastern Hellbenders released in Indiana, and 3) emphasizes the importance of translocations in herpetofauna conservation and management
The ecology and genetics of the eastern hellbender Cryptobranchus alleganiensis alleganiensis
No full textNorth America\u27s giant salamander, the eastern hellbender (Cryptobranchus alleganiensis alleganiensis) is a long-lived, obligately aquatic salamander. Thus, it is a model species for investigating the genetic architecture of lotic systems. However, many populations have experienced precipitous declines and are at risk for loss of genetic diversity and increased extinction. As a result, there is a need to assess population structure and genetic diversity across the riverscape to inform management efforts. My dissertation focuses on using molecular methods and population modeling to examine the conservation biology of this cryptic species. In chapter one, I assessed the genetic structure at the range-wide and landscape or drainage level (across stream hierarchical networks of basins, sub-basins, and stream reaches). I found relatively high levels of genetic diversity range-wide, indicating high quality genetic stock for conservation efforts. Across the geographic distribution, I found two genetically differentiated groups at the range-wide scale: 1) the Ohio River drainage and 2) the Tennessee River drainage. At the drainage scale, I found most of the genetic variation partitioned within streams. I also found a strong pattern of isolation by distance at the drainage scale. In chapter two, I used molecular markers as genetic tags to assess the retention of Passive Integrated Transponder tags for eastern hellbenders within the Blue River. This provided a method for validating estimates of population size based on previous mark-recapture studies for Indiana\u27s sole remaining population of eastern hellbenders. Lastly, in chapter three, I developed a stage-structured life-history model for the Blue River to assess the efficacy of management strategies on population growth and long-term population viability. I found a high probability of complete extirpation unless management practices are implemented to ensure adult presence and increase early life-stage survival. Several management actions are recommended to stabilize population projections, including initiating a head-starting program and conducting female-biased translocations to facilitate population growth. When taken together, this research provides a framework to inform wildlife management strategies and further our understanding of the conservation genetics and population dynamics of this cryptic salamander species
Cutaneous Microbial Ecology of Giant Salamanders: Implications for Conservation and Management
No full textMicrobial symbionts impact important host physiological processes such as immunity and metabolic regulation. As a result, describing microbial communities is useful for a holistic understanding of host health. The amphibian skin serves as an excellent model for understanding the influence of the microbiome on host fitness. Within this class, the skin is a vital organ used for respiration, osmoregulation and immunity. In addition, the amphibian skin harbors diverse microbial communities that provide protection against common amphibian pathogens. In efforts to combat amphibian declines associated with pathogens, researchers are characterizing the cutaneous microbiome as a resource for disease management. Hellbender salamanders (Cryptobranchus alleganiensis) provide an ideal system to evaluate skin microbial communities under the scope of conservation. Hellbenders are threatened across their range, and conservation programs require information on ways to mitigate disease spread associated with translocations and re-introductions. In addition, the Ozark hellbender subspecies (C. a. bishopi) exhibits chronic wounds associated with bacterial infections, whereas the eastern hellbender (C. a. alleganiensis) does not. As a result, there is a need to evaluate the structure of the cutaneous microbiota of hellbenders, to investigate the microbiome composition of Ozark hellbender wound tissue, and to determine the genetic and evolutionary factors that influence microbial community composition. I characterized the skin microbiome of hellbenders across the range of both subspecies which are located in the eastern United States. I obtained microbiota samples from the dorsal skin of both hellbender subspecies and from the chronic wounds in wild Ozark hellbenders. I applied 16S rRNA gene amplicon sequencing and bioinformatics pipelines to describe the bacterial communities of all samples. In addition, I obtained estimates of allele frequency and diversity for the immune system major histocompatibility complex (MHC) IIB gene for individuals from both hellbender subspecies. To evaluate evolutionary-associated differentiation in the skin microbiome, I compared the microbiome composition of eastern and Ozark hellbender subspecies. I also evaluated differences in community composition between wounds and the healthy skin of Ozark hellbenders. Within each subspecies’ range, I estimated the effect of population genetic structure and geographical location on operational taxonomic unit (OTU) turnover and community differentiation. Finally, I measured MHC-IIB allele diversity within each subspecies, and assessed linkages between the MHC and microbiome diversity and composition. Microbiome analysis and immune gene characterization derived substantial results important for the conservation of this species. First, I observed significant differentiation of hellbender skin communities among populations driven by clumped operational taxonomic unit turnover. In addition, there were pronounced differences in the composition of bacterial communities on the skin of Ozark and eastern hellbenders. These patterns indicate that co-evolutionary adaptations have occurred between the host subspecies and their microbiome. In contrast to the Ozark hellbender healthy skin, bacterial community samples on chronic wounds had increased community richness. While the results of my investigations do not identify specific bacterial pathogens, richness differences between wounds and healthy skin suggest that symbiont and environmental bacteria opportunistically colonize exposed wound tissue. Ozark hellbenders also possessed reduced diversity in the MHC IIB gene compared to the eastern subspecies. Reduced immunocompetence due to loss of MHC divergence is among the first concrete explanations for the presence of chronic wounds in Ozark hellbenders. Finally, common MHC-IIB allele presence and divergence were noted to significantly define differences in microbiome composition among individuals in both subspecies. Thus, cutaneous immunity in amphibians is dependent on synergistic contributions by host and microbial traits. I provide a guide for the incorporation of MHC and microbiome data into current conservation practices. Current hellbender management practices should continue to prioritize the maintenance of genome-wide diversity in captive/wild populations. Moreover, preservation of MHC diversity in captive/wild populations should be a secondary goal given the presence of disease in wild populations. Additionally, if differences in the cutaneous microbiome exist between source and supplemented populations, there is a need to evaluate ways to reduce dysbiosis caused by management approaches (e.g., sterile captive environment). It is necessary to investigate how genetic/microbial diversity management can benefit the efforts of captive breeding and rearing programs in hellbenders and other amphibian species. Incorporating a holistic approach into amphibian management has great potential to improve the success of current and future conservation efforts worldwide
The effects of forest management on terrestrial salamanders
No full textMaintaining a balance of timber production and conservation in forest management requires an understanding of how timber harvest techniques affect wildlife species. Terrestrial salamanders are useful indicators of mature forest ecosystem health due to their importance to ecosystem processes and their sensitivity to environmental change. The topic of timber harvests and their effect on terrestrial salamanders has received much attention in the literature but disagreements and uncertainty about the severity and duration of these effects persist. I employed artificial cover objects (ACOs) to monitor salamander relative abundance in six forest management treatments both before and after harvests. Prior to harvests, I assessed the efficacy of two cover-object materials in sampling forest herpetofauna. In a side-by-side comparison of 930 pairs of ACOs, salamanders were found more under wood objects than plastic objects (p \u3c 0.001), a result likely due to a greater capacity of wood objects to retain moisture and buffer temperature fluctuations. Pre-harvest data showed little variation in mean salamander counts across treatment types, but counts were greater in spring than fall. Counts varied by slope aspect in the fall but not the spring. Mean encounters of Eastern Red-backed (Plethodon cinereus) and Northern Slimy Salamanders (P. glutinosus) declined from pre- to post-harvest in group selection cuts (p \u3c 0.001); however, mean encounters of red-backed salamanders also declined in uncut control sites (p = 0.025). The effect of sample period was statistically significant for all species tested (p \u3c 0.001), suggesting high temporal variation in salamander abundance. Average daily air temperature was negatively correlated with counts of red-backed and Northern Zigzag Salamanders (P. dorsalis ; rs ≈ -0.43, p \u3c 0.001). In general, harvests which removed the forest canopy had a negative effect on salamander relative abundance during the years immediately following harvest. Salamander declines were not as severe as those seen in most previous research, a fact which may be explained in part by the relatively small size (≤ 4 ha) of the harvests examined here. I found no effect of controls, shelterwoods, and forested sites adjacent to harvests. Much of the variation in salamander counts is likely driven by seasonal patterns in precipitation and temperature. Longer-term monitoring will be necessary to understand the full impacts of forest management on terrestrial salamanders
Effects of forest management on the ecology and behavior of Eastern Box Turtles
No full textDeclines in long-lived and geographically widespread forest animals, such as the case with Eastern Box Turtles (Terrapene carolina carolina ), warrants investigation. Despite declines, this species\u27 ability to endure in a range of available habitat and its physiological ties to environmental flux make it ideal for study of habitat use and selection amid anthropogenic disturbances. For my thesis work, I focused on investigating the ecology and behavior of Eastern Box Turtles following timber harvests. As part of the Hardwood Ecosystem Experiment, I used nine experimental forest management sites to investigate the effects of clearcut harvest openings and group selection harvest openings on box turtles. I used standard homing radiotelemetry to collect GPS location, morphometric, temperature, and behavior data on 50 adult Eastern Box Turtles. I conducted the majority of this work during the active seasons (May–October) but during the winter of 2010 I investigated the hibernal thermal ecology within clearcut harvest openings. Combined with the radiotelemetry data previously collected on these turtles from 2007-08, I was able to measure the effects of the harvests by analyses of movement parameters and temperatures. I found that timber harvests had no effect on the typical measurement of home range size, 100% Minimum Convex Polygons (MCP), however the MCPs here are 33% larger than any other published report for this species. Additionally, I found that turtles decreased the daily distances they traveled by approximately 30%, but their thermal optima increased by 8% following the harvests. Microclimates inside the timber harvests were significantly warmer (29%) in the summer and colder (31%) in the winter than forested habitats, effectively excluding many animals from consistently using them. Instead of leaving the harvested areas, however, turtles continued to use them differently. During the active season, box turtles used the edges of harvest areas apparently for behavioral thermoregulation and possibly for foraging. Turtles that used the harvest areas maintained 9% higher body temperatures during the active season than those that did not. During the winter, turtles generally burrowed to 10 cm for overwintering, but depth varied by slope and gender. I found that the depth influenced the emergence timing, which was also correlated with a soil-surface temperature inversion. A single female turtle that hibernated in a group-selection harvest opening had an estimated burrowing depth of nearly 30 cm to maintain her hibernal body temperature. Moreover, I estimated the annual survival rate (96.2%) of box turtles in our population, the first for the Midwest. The investigation of ecological mechanisms underlying species declines has become paramount in conservation literature. Simply reporting the extirpation of populations without testing mechanistic causes does little to promote conservation management. Herein, I investigated temporal thermal habitat availability, habitat use, thermal behavior, survival, and intersexual differences among Eastern Box Turtles within the framework of a managed forest setting
Population estimation, spatial ecology, and health status of eastern hellbenders in Indiana
No full textThe eastern hellbender (Cryptobranchus alleganiensis alleganiensis ) is a member of an ancient salamander family comprised of three extant species. They require cool, swift flowing rivers and streams with rocky substrates and abundant large, flat rocks for shelter. Once commonly found in many rivers and streams in the eastern United States, the hellbender has experienced precipitous population declines and is now rare or extirpated throughout much of its historical distribution. While the exact cause of the declines is unknown, habitat degradation is suspected as the primary stressor. In Indiana, the hellbender’s distribution has been reduced to one low density population in the Blue River in southern Indiana. Many studies have focused on various aspects of hellbender ecology; however, most have focused on populations characterized by considerably higher density of animals. Individual behaviors may differ as a result of varying densities and habitat conditions. With this study, we intend to elucidate the behaviors of the hellbender under demographic and environmental conditions, which differ considerably from previous studies and hope to identify potential factors contributing to their decline. Our objectives were to: (1) estimate population abundance and structure, (2) investigate the home range, movement patterns, and habitat use, and (3) evaluate the physical health of the population and its surrounding environment in order to develop a better overall understanding of the problems facing the population. Surveys were conducted in September 2007, June 2008 – October 2008, and July 2009 – September 2009. Blood was drawn from all individuals for blood chemistry analysis. Twenty-one hellbenders were implanted with radio-transmitters at eight sites and water quality was examined at a subset of seven of these locations. Eighty-eight hellbenders were captured during surveys. Using the Jolly-Seber model, we estimated a population density of 0.06 individuals/100 m2 for our study sites. Minimum convex polygon (100%) home range estimates were larger than reported in previous studies and home ranges for males were significantly larger than for females’. Most plasma chemistry parameters were similar between sexes and comparable to other reported populations. Vitellogenin was found to be an accurate means for gender identification up to two months prior to the breeding season. Our study represents a portion of an ongoing comprehensive assessment of hellbender ecology and will provide valuable information for future management efforts
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