Investigating the health of free-ranging Blanding’s turtles (Emydoidea blandingii) in Northern Illinois through epidemiologic tools, individual, and population health modeling

Over the last century, increasing human populations and urbanization have led to significant alterations to terrestrial, marine, and wetland environments resulting in declines in wildlife populations and overall biodiversity. Among the most affected taxa globally are chelonians, with 35% of species within the order Testudines endangered or critically endangered. Within Illinois, one of the most endangered chelonian species is the Blanding’s turtle (Emydoidea blandingii). Throughout the work of this dissertation, the individual and population health of Blanding’s turtles was evaluated to address practical methodological shortcomings and strengthen statistical conclusions. Firstly, a pathogen threat emerged within Blanding’s turtles in Illinois that was attributed to Emydomyces testavorans, but diagnosis was wrought with difficulties. Thus, I determined optimal sampling methods using latent class modeling. I demonstrated that combined oral-cloacal-shell swabs and water qPCR were highly sensitive (98.0% and 94.0%, respectively) and adequately specific (74.9% and 88.3%, respectively) and I recommend these testing methods for routine E. testavorans surveillance. In addition to this existing assay, a novel TaqMan real-time PCR assay was developed to aid epidemiologic investigation of the novel Trachemys herpesvirus 1 (TrHV1) in Blanding’s turtles. Herpesviruses are among the most impactful pathogens described in chelonians and are frequently associated with a range of presentations across hosts with the potential for severe morbidity and mortality. Trachemys herpesvirus 1 (TrHV1) has been reported in sympatric red-eared and yellow-bellied sliders (Trachemys scripta elegans and Trachemys scripta scripta, respectively), but is largely understudied in these species as well as aberrant hosts like Blanding’s turtles. The assay meets criteria for acceptable qPCR assays, thereby facilitating further epidemiologic studies and proactive disease management efforts. Environmental contamination from heavy metals poses another threat to turtle health, but remains characterized. To address this, plasma, liver, and water concentrations of heavy metals were collected from free-ranging Blanding’s turtles and sympatric red-eared sliders (as sentinel species) and from their habitats) as well as their habitats. Significant exposure to mercury, cobalt, and arsenic was detected, with several metals (selenium, aluminum, vanadium, iron, and cobalt) found to be correlated with compromised turtle health. Mercury concentrations exceeded safe drinking levels at several sites, with significant elevations at a site in a predominantly industrial area. Findings highlighted the importance of utilizing both circulating and stored metal concentrations to evaluate individual and population health, as well as to establish biologically relevant baselines and assess sublethal effects in increasingly contaminated habitats. Determinants of health in adult female turtles were then assessed using existing and recently developed modalities to identify drivers of gravidity, nesting success, and offspring success. Individual clinicopathologic parameters and overall health status were associated with gravidity, with unhealthy females demonstrating reduced reproductive frequency. Furthermore, maternal health (e.g. traumatic injuries) directly affected offspring health status, reflecting reduced maternal investments. Beyond the effects of health on fecundity, this research demonstrates the effects of individual health on population sustainability. Comprehensive health assessments of 3,396 Blanding’s turtle encounters revealed indications of poor health in 16% of turtle encounters. The predictive capabilities of models to assess the health of turtles were poor, reflecting the subtle effects of infectious and non-infectious disease in Blanding’s turtles. Additionally, longitudinal analysis of 15,282 turtle encounters from 1,233 individuals demonstrated that unhealthy turtles faced a 138% higher risk of death compared to healthy counterparts. Several predictors such as weight loss and reduced activity levels increased mortality risk. Finally, a population viability analysis with integrated disease modeling scenarios revealed the impact that even low initial prevalences of disease can have on long-term population resiliency. These outcomes highlight the need for proactive disease surveillance using techniques like those presented here. Collectively, this dissertation integrates epidemiological tools and statistical modeling to illuminate how a comprehensive approach to health can improve conservation outcomes in imperiled populations.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Ecol, Evol, Conservation Biol

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Moorhead, Kaitlin

Contributors dc:contributor

• Allender, Matt
• Smith, Rebecca
• Allan, Brian
• Adamovicz, Laura

• Blanding's Turtle
• Health
• Epidemiology

Statement dc:rights

• Copyright 2025 Kaitlin Moorhead

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/130170

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F130170