Effects of landscape composition on wetland occupancy by Blanding’s Turtles (Emydoidea blandingii) as determined by environmental DNA and visual surveys

Habitat loss and degradation have led to the extinction of many species worldwide. The endangered Blanding’s Turtle (Emydoidea blandingii (Holbrook, 1838)), a semi-aquatic freshwater turtle, occupies a wide range of wetlands and landscapes primarily in southeastern Canada and the Great Lakes region of the United States. We explored whether the probability of wetland occupancy by Blanding’s Turtles is affected by the surrounding landscape. We used visual surveys, environmental DNA, and Atlas data to document the presence of Blanding’s Turtles in wetlands in Ottawa, Ontario, Canada. We tabulated landscape composition at multiple scales surrounding the wetlands to determine whether landscape composition can predict wetland occupancy. Generally, wetlands surrounded by forest and other undisturbed lands were most likely to harbour Blanding’s Turtles, whereas those surrounded by more human-disturbed lands were least likely to harbour Blanding’s Turtles. Larger wetlands and a high proportion of wetlands in the surrounding landscape also increased the probability of occupancy by Blanding’s Turtles. Finally, older wetlands were more likely to be occupied by Blanding’s Turtles. The ability to estimate a species’ probability of occupancy can aid in conservation efforts, such as critical habitat delineation.

Nest site selection and nesting behavior of the mud turtle Kinosternon scorpiodes (Testudines, Kinosternidae) in Palo Verde National Park, Costa Rica: implications for management

Habitat selection is the process whereby individuals preferentially use, or occupy, a non-random set of available habitats. At the same time, nest site selection is defined as the placement of eggs by females at sites differing from random sites within a delimited area. We located 59 nests of the mud turtle Kinosternon scorpioides in Palo Verde National Park (PVNP) in Northwestern Costa Rica. We compared eight microhabitat variables at nest sites against those at random sites. Females significantly placed their eggs at sites with more understory, leaf litter cover, and greater leaf litter depth than in random sites. Additionally, females selected sites with lower air and soil temperature and lower air humidity. Palo Verde NP is subject to active management actions designed to control invasive plant species in the wetland, namely cattail (Thypha domingensis Pers.). The main actions have been cattle grazing, controlled fires, and mechanical crushing of vegetation. We found that habitat quality in nesting areas is being threatened by at least one of these actions: cattle grazing. This is detrimental for three microhabitat traits that turtles select for nesting sites: understory cover, leaf litter cover, and leaf litter depth. The continued degradation of microhabitats at nesting areas of K. scorpioides at PVNP could be affecting recruitment due to embryo survivorship.

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.