MEASURING FAT CONTENT USING COMPUTED TOMOGRAPHY TO ESTABLISH A BODY CONDITION INDEX IN FREE-RANGING BLANDING'S TURTLES (EMYDOIDEA BLANDINGII) IN ILLINOIS

Body condition scoring facilitates healthcare monitoring in Hermann's Tortoises (Testudo hermanni ssp.)

Clinical assessment of body condition is crucial in captive and free-ranging reptiles, since a large percentage of diseases result from inadequate nutrition. However, preventive health care is restricted by the lack of a practical method for the assessment in tortoises. Pre-existing evaluation systems based on weight and shell measurements are laborious and ignore the clinical presentation of the animal. The present study aimed to facilitate the assessment by establishing a body condition score. A total of 373 Hermann's Tortoises (Testudo hermanni) (n = 281 tortoises kept as pets in Germany and n = 92 tortoises originating from a free-ranging population (68) or a rearing station (24) in France) were examined and data (weight (g), carapace length (cm), width (cm), height (cm)) were recorded in a standard protocol between October 2020 and October 2021. A modified version of a body condition score for Mojave Desert Tortoises (Gopherus agassizii) (1 = cachectic, 3 = ideal, 5 = obese) was utilized and tested against pre-existing shell measurement systems (Jackson's ratio, body condition index, volume condition index, circumferential product). German captive tortoises were significantly heavier and larger than French specimens. In the Spearman's correlation matrix, the body condition score showed a statistically significant correlation with all measurement methods in the total population of captive tortoises (Testudo hermanni boettgeri), with a medium correlation strength, and a lack of correlation in free-ranging tortoises (Testudo hermanni hermanni). However, individual animal data suggested misleading results of mathematical equations in terms of body condition. Clinical evaluation of tortoises, including a body condition score, should be considered essential to provide good healthcare and should be an integral part of general examination.

Assessment of glucocorticoids, sex steroids, and innate immunity in wild red-eared slider turtles (Trachemys scripta elegans)

When access to resources is limited, organisms must shift energy investment among physiological processes to survive, reproduce, and respond to unpredictable events. The shifting of these limited resources among processes may result in physiological tradeoffs, often mediated by glucocorticoids. We assessed relationships among the physiological processes of immunity, reproduction, and the stress response in wild adult red-eared slider turtles (Trachemys scripta elegans). Red-eared sliders exhibit a multi-clutching reproductive strategy that requires high energetic investment in reproduction at the beginning of the nesting season in females. Males mate in spring and undergo spermatogenesis and mating in late summer/early fall. We expected to observe tradeoffs when investment toward reproductive processes was particularly demanding. To test this, we subjected 123 individuals to a standardized acute stressor and collected blood to measure innate immunocompetence and circulating steroid hormone concentrations. Tradeoffs between female reproduction and immunocompetence occurred early in the nesting season. This high reproductive investment was evident by heightened circulating progesterone and reduced baseline innate immunity. Corticosterone (CORT) was also high during this period, indicating a role in facilitating allocation of energy. Tradeoffs were not as evident in males, though males upregulated innate immune function, baseline CORT, and testosterone prior to fall spermatogenesis and mating. Throughout the entire sampling period, both males and females increased CORT and immunocompetence following the acute standardized stressor. Taken together, we concluded that reproduction requires shifts in energy allocation in during the highest reproductive period for females but all individuals in this population remain able to respond to the standardized stressor even during increased reproductive investment. These findings reinforce the continuing evidence that physiological relationships are context-dependent and resource demands are dynamic across the reproductive season.

COMPUTED TOMOGRAPHY FOR MEASURING BODY FAT RESERVES IN THE THREATENED MOJAVE DESERT TORTOISE (GOPHERUS AGASSIZII)

Noninvasive methods for measuring fat reserves in both captive and free-ranging animals are important for monitoring individual and population health, but chelonian anatomy and physiology present challenges to accurate measurements. Standard field-based methods for assessing body condition in Mojave desert tortoises (Gopherus agassizii) involve the qualitative body condition score, which relies on the apparent height of the temporalis muscle relative to the sagittal crest (in addition to other characteristics) and quantitative body condition indices that measure relative mass at size. However, it is unclear how these metrics relate to body fat reserves in this species. The aims of this study were to (1) describe the use of noninvasive computed tomography in measuring body fat volume of Mojave desert tortoises, (2) describe the location of fat reserves, (3) investigate relationships between fat reserves and body condition score and body condition index, and (4) explore whether relative temporalis muscle depth, measured via computed tomography, correlates with body condition score. Body condition scores were assessed for eight captive Mojave desert tortoises prior to euthanasia, and computed tomography was performed postmortem to quantify fat volume and measure temporalis muscle depth. At necropsy, the distribution of fat was documented. Fat volume calculated by computed tomography ranged from 2.83 to 145.38 cm³ (0.07-2.5% body volume). Neither qualitative body condition score nor quantitative body condition index was correlated with fat volume. Bladder content did not compromise body condition index. Body condition score was not correlated with relative temporalis muscle depth. Computed tomography is a noninvasive method for successfully identifying fat reserves and estimating total fat volume in Mojave desert tortoises. The lack of a relationship between computed tomography-determined metrics and commonly used body condition metrics indicates that computed tomography fills a critical gap in the health assessment tool kit for captive and free-ranging Mojave desert tortoises.

Plasma electrophoresis profiles of Blanding's turtles (Emydoidea blandingii) and influences of month, age, sex, health status, and location

Baseline plasma electrophoresis profiles (EPH) are important components of overall health and may aid in the conservation and captive management of species. The aim of this study was to establish plasma protein fractions for free-ranging Blanding’s turtles (Emydoidea blandingii) and evaluate differences due to age class (adult vs. sub-adult vs. juvenile), sex (male, female, or unknown), year (2018 vs. 2019), month (May vs. June vs. July), health status, and geographical location (managed vs. unmanaged sites). Blood samples were obtained from 156 Blanding’s turtles in the summer of 2018 and 129 in 2019 at two adjacent sites in Illinois. Results of the multivariate analysis demonstrated that age class, sex, year, month, health status, and geographical location all contributed to the variation observed in free-ranging populations. Adult females had the highest concentration of many protein fractions, likely associated with reproductive activity. Juveniles had lower protein concentrations. Temperature and rainfall differences between years impacted concentrations between 2018 and 2019, while May and June of both years saw higher levels in some protein fractions likely due to peak breeding and nesting season. Individuals with evidence of trauma or disease also showed increased plasma protein fractions when compared to those that were considered healthy. The two sites showed a wide/large variation over the two years. All of these factors emphasize the importance of considering multiple demographic or environmental factors when interpreting the EPH fractions. Establishing ranges for these analytes will allow investigation into disease prevalence and other environmental factors impacting this endangered species.

Physiological Health and Survival of Captive-Reared and Released Juvenile Blanding's Turtles

AbstractConservation translocations are important in maintaining viable wildlife populations of vulnerable species within their indigenous ranges. To be effective, population restoration efforts (e.g., head start programs) must consider the species' life history, regional ecology, and physiology and the health status of wild and translocated populations. The decline of Blanding's turtles (Emydoidea blandingii) has prompted the initiation of head start programs, but the health and short-term survival of head-started juveniles released to the wild is largely unknown. From May to October 2016 and 2017, we radio tracked captive-reared, recently released juvenile Blanding's turtles and monitored their survivorship and monthly physiological health. We aimed to (1) compare physiological metrics of juveniles before and after release from captivity and between head-started cohorts, (2) identify seasonal trends in physiological metrics of recently released juveniles, (3) compare physiological metrics of recently released and formerly released juveniles, and (4) identify predictors of juvenile survivorship after release from captivity. Juvenile short-term survival was low compared with other studies. Most physiological metrics did not change after release from captivity, negating significant juvenile stress before or after release. Physiological metrics for recently released cohorts varied seasonally, suggesting that these juveniles were likely in good health. Some physiological metrics differed between recently released and formerly released juveniles, demonstrating a potential postrelease acclimatization period. Finally, no physiological metrics significantly predicted survival, but surviving juveniles had a higher percentage of fat. In all, juvenile deaths were not due to poor turtle health but rather to predation from human-subsidized mesocarnivores. Therefore, head-started juvenile Blanding's turtles released in suburban areas may benefit from antipredator training and mesocarnivore control at release sites.

CHARACTERIZING THE EPIDEMIOLOGY OF HISTORIC AND NOVEL PATHOGENS IN BLANDING'S TURTLES (EMYDOIDEA BLANDINGII)

Pathogens such as herpesviruses, Mycoplasma spp., and frog virus 3-like ranavirus have contributed to morbidity and mortality in many species of free-living and zoo-maintained chelonians. However, their prevalence is understudied in Blanding's turtles (Emydoidea blandingii) across North America. To assess the presence of these pathogens, Blanding's turtles were sampled in Lake County, Illinois, in 2017 (N = 213) and 2018 (N = 160). DNA from cloacal-oral swabs was assayed for four ranaviruses, three Mycoplasma spp., two Salmonella spp., Emydoidea herpesvirus 1 (EBHV1), and tortoise intranuclear coccidiosis (TINC) using a multiplex quantitative polymerase chain reaction (qPCR). Pathogens were most frequently detected in adult turtles (n = 25) and rarely in subadults (n = 2) or juveniles (n = 1). EBHV1 was detected in 22 individuals with no clinical signs of illness, most (n = 20) occurring in the month of May (P < 0.0001). EBHV1 cases at one study site significantly clustered within the same 0.64-km area from 17 to 22 May 2017 (P < 0.0001) and 14 to 15 May 2018 (P = 0.0006). Individuals were rarely positive for Salmonella typhimurium (n = 6). A novel Mycoplasma sp. sharing high homology with other emydid Mycoplasma spp. was detected in one turtle with nasal discharge. Neither TINC nor any ranaviruses were detected. Continued monitoring of this population and habitat may facilitate identification of risk factors for pathogen occurrence and clarify the impact of infectious diseases on Blanding's turtle conservation outcomes.